linux/drivers/serial/8250.c

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/*
* linux/drivers/char/8250.c
*
* Driver for 8250/16550-type serial ports
*
* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
*
* Copyright (C) 2001 Russell King.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* A note about mapbase / membase
*
* mapbase is the physical address of the IO port.
* membase is an 'ioremapped' cookie.
*/
#if defined(CONFIG_SERIAL_8250_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_reg.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <linux/nmi.h>
#include <linux/mutex.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/irq.h>
#include "8250.h"
#ifdef CONFIG_SPARC
#include "suncore.h"
#endif
/*
* Configuration:
* share_irqs - whether we pass IRQF_SHARED to request_irq(). This option
* is unsafe when used on edge-triggered interrupts.
*/
static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
static unsigned int nr_uarts = CONFIG_SERIAL_8250_RUNTIME_UARTS;
static struct uart_driver serial8250_reg;
static int serial_index(struct uart_port *port)
{
return (serial8250_reg.minor - 64) + port->line;
}
static unsigned int skip_txen_test; /* force skip of txen test at init time */
/*
* Debugging.
*/
#if 0
#define DEBUG_AUTOCONF(fmt...) printk(fmt)
#else
#define DEBUG_AUTOCONF(fmt...) do { } while (0)
#endif
#if 0
#define DEBUG_INTR(fmt...) printk(fmt)
#else
#define DEBUG_INTR(fmt...) do { } while (0)
#endif
#define PASS_LIMIT 256
serial: 8250: add serial transmitter fully empty test When controlling an industrial radio modem it can be necessary to manipulate the handshake lines in order to control the radio modem's transmitter, from userspace. The transmitter should not be turned off before all characters have been transmitted. serial8250_tx_empty() was reporting that all characters were transmitted before they actually were. === Discovered in parallel with more testing and analysis by Kees Schoenmakers as follows: I ran into an NetMos 9835 serial pci board which behaves a little different than the standard. This type of expansion board is very common. "Standard" 8250 compatible devices clear the 'UART_LST_TEMT" bit together with the "UART_LSR_THRE" bit when writing data to the device. The NetMos device does it slightly different I believe that the TEMT bit is coupled to the shift register. The problem is that after writing data to the device and very quickly after that one does call serial8250_tx_empty, it returns the wrong information. My patch makes the test more robust (and solves the problem) and it does not affect the already correct devices. Alan: We may yet need to quirk this but now we know which chips we have a way to do that should we find this breaks some other 8250 clone with dodgy THRE. Signed-off-by: Dick Hollenbeck <dick@softplc.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Cc: Kees Schoenmakers <k.schoenmakers@sigmae.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-09 20:31:34 +00:00
#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
/*
* We default to IRQ0 for the "no irq" hack. Some
* machine types want others as well - they're free
* to redefine this in their header file.
*/
#define is_real_interrupt(irq) ((irq) != 0)
#ifdef CONFIG_SERIAL_8250_DETECT_IRQ
#define CONFIG_SERIAL_DETECT_IRQ 1
#endif
#ifdef CONFIG_SERIAL_8250_MANY_PORTS
#define CONFIG_SERIAL_MANY_PORTS 1
#endif
/*
* HUB6 is always on. This will be removed once the header
* files have been cleaned.
*/
#define CONFIG_HUB6 1
#include <asm/serial.h>
/*
* SERIAL_PORT_DFNS tells us about built-in ports that have no
* standard enumeration mechanism. Platforms that can find all
* serial ports via mechanisms like ACPI or PCI need not supply it.
*/
#ifndef SERIAL_PORT_DFNS
#define SERIAL_PORT_DFNS
#endif
static const struct old_serial_port old_serial_port[] = {
SERIAL_PORT_DFNS /* defined in asm/serial.h */
};
#define UART_NR CONFIG_SERIAL_8250_NR_UARTS
#ifdef CONFIG_SERIAL_8250_RSA
#define PORT_RSA_MAX 4
static unsigned long probe_rsa[PORT_RSA_MAX];
static unsigned int probe_rsa_count;
#endif /* CONFIG_SERIAL_8250_RSA */
struct uart_8250_port {
struct uart_port port;
struct timer_list timer; /* "no irq" timer */
struct list_head list; /* ports on this IRQ */
unsigned short capabilities; /* port capabilities */
unsigned short bugs; /* port bugs */
unsigned int tx_loadsz; /* transmit fifo load size */
unsigned char acr;
unsigned char ier;
unsigned char lcr;
unsigned char mcr;
unsigned char mcr_mask; /* mask of user bits */
unsigned char mcr_force; /* mask of forced bits */
unsigned char cur_iotype; /* Running I/O type */
/*
* Some bits in registers are cleared on a read, so they must
* be saved whenever the register is read but the bits will not
* be immediately processed.
*/
#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
unsigned char lsr_saved_flags;
#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
unsigned char msr_saved_flags;
};
struct irq_info {
struct hlist_node node;
int irq;
spinlock_t lock; /* Protects list not the hash */
struct list_head *head;
};
#define NR_IRQ_HASH 32 /* Can be adjusted later */
static struct hlist_head irq_lists[NR_IRQ_HASH];
static DEFINE_MUTEX(hash_mutex); /* Used to walk the hash */
/*
* Here we define the default xmit fifo size used for each type of UART.
*/
static const struct serial8250_config uart_config[] = {
[PORT_UNKNOWN] = {
.name = "unknown",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_8250] = {
.name = "8250",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16450] = {
.name = "16450",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16550] = {
.name = "16550",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16550A] = {
.name = "16550A",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO,
},
[PORT_CIRRUS] = {
.name = "Cirrus",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16650] = {
.name = "ST16650",
.fifo_size = 1,
.tx_loadsz = 1,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16650V2] = {
.name = "ST16650V2",
.fifo_size = 32,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
UART_FCR_T_TRIG_00,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16750] = {
.name = "TI16750",
.fifo_size = 64,
.tx_loadsz = 64,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
UART_FCR7_64BYTE,
.flags = UART_CAP_FIFO | UART_CAP_SLEEP | UART_CAP_AFE,
},
[PORT_STARTECH] = {
.name = "Startech",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16C950] = {
.name = "16C950/954",
.fifo_size = 128,
.tx_loadsz = 128,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16654] = {
.name = "ST16654",
.fifo_size = 64,
.tx_loadsz = 32,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
UART_FCR_T_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16850] = {
.name = "XR16850",
.fifo_size = 128,
.tx_loadsz = 128,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_RSA] = {
.name = "RSA",
.fifo_size = 2048,
.tx_loadsz = 2048,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_11,
.flags = UART_CAP_FIFO,
},
[PORT_NS16550A] = {
.name = "NS16550A",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_NATSEMI,
},
[PORT_XSCALE] = {
.name = "XScale",
.fifo_size = 32,
.tx_loadsz = 32,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_UUE,
},
[PORT_RM9000] = {
.name = "RM9000",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO,
},
[PORT_OCTEON] = {
.name = "OCTEON",
.fifo_size = 64,
.tx_loadsz = 64,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO,
},
[PORT_AR7] = {
.name = "AR7",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_00,
.flags = UART_CAP_FIFO | UART_CAP_AFE,
},
[PORT_U6_16550A] = {
.name = "U6_16550A",
.fifo_size = 64,
.tx_loadsz = 64,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_AFE,
},
};
#if defined(CONFIG_MIPS_ALCHEMY)
/* Au1x00 UART hardware has a weird register layout */
static const u8 au_io_in_map[] = {
[UART_RX] = 0,
[UART_IER] = 2,
[UART_IIR] = 3,
[UART_LCR] = 5,
[UART_MCR] = 6,
[UART_LSR] = 7,
[UART_MSR] = 8,
};
static const u8 au_io_out_map[] = {
[UART_TX] = 1,
[UART_IER] = 2,
[UART_FCR] = 4,
[UART_LCR] = 5,
[UART_MCR] = 6,
};
/* sane hardware needs no mapping */
static inline int map_8250_in_reg(struct uart_port *p, int offset)
{
if (p->iotype != UPIO_AU)
return offset;
return au_io_in_map[offset];
}
static inline int map_8250_out_reg(struct uart_port *p, int offset)
{
if (p->iotype != UPIO_AU)
return offset;
return au_io_out_map[offset];
}
#elif defined(CONFIG_SERIAL_8250_RM9K)
static const u8
regmap_in[8] = {
[UART_RX] = 0x00,
[UART_IER] = 0x0c,
[UART_IIR] = 0x14,
[UART_LCR] = 0x1c,
[UART_MCR] = 0x20,
[UART_LSR] = 0x24,
[UART_MSR] = 0x28,
[UART_SCR] = 0x2c
},
regmap_out[8] = {
[UART_TX] = 0x04,
[UART_IER] = 0x0c,
[UART_FCR] = 0x18,
[UART_LCR] = 0x1c,
[UART_MCR] = 0x20,
[UART_LSR] = 0x24,
[UART_MSR] = 0x28,
[UART_SCR] = 0x2c
};
static inline int map_8250_in_reg(struct uart_port *p, int offset)
{
if (p->iotype != UPIO_RM9000)
return offset;
return regmap_in[offset];
}
static inline int map_8250_out_reg(struct uart_port *p, int offset)
{
if (p->iotype != UPIO_RM9000)
return offset;
return regmap_out[offset];
}
#else
/* sane hardware needs no mapping */
#define map_8250_in_reg(up, offset) (offset)
#define map_8250_out_reg(up, offset) (offset)
#endif
static unsigned int hub6_serial_in(struct uart_port *p, int offset)
{
offset = map_8250_in_reg(p, offset) << p->regshift;
outb(p->hub6 - 1 + offset, p->iobase);
return inb(p->iobase + 1);
}
static void hub6_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
outb(p->hub6 - 1 + offset, p->iobase);
outb(value, p->iobase + 1);
}
static unsigned int mem_serial_in(struct uart_port *p, int offset)
{
offset = map_8250_in_reg(p, offset) << p->regshift;
return readb(p->membase + offset);
}
static void mem_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
writeb(value, p->membase + offset);
}
static void mem32_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
writel(value, p->membase + offset);
}
static unsigned int mem32_serial_in(struct uart_port *p, int offset)
{
offset = map_8250_in_reg(p, offset) << p->regshift;
return readl(p->membase + offset);
}
static unsigned int au_serial_in(struct uart_port *p, int offset)
{
offset = map_8250_in_reg(p, offset) << p->regshift;
return __raw_readl(p->membase + offset);
}
static void au_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
__raw_writel(value, p->membase + offset);
}
static unsigned int tsi_serial_in(struct uart_port *p, int offset)
{
unsigned int tmp;
offset = map_8250_in_reg(p, offset) << p->regshift;
if (offset == UART_IIR) {
tmp = readl(p->membase + (UART_IIR & ~3));
return (tmp >> 16) & 0xff; /* UART_IIR % 4 == 2 */
} else
return readb(p->membase + offset);
}
static void tsi_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
if (!((offset == UART_IER) && (value & UART_IER_UUE)))
writeb(value, p->membase + offset);
}
static void dwapb_serial_out(struct uart_port *p, int offset, int value)
{
int save_offset = offset;
offset = map_8250_out_reg(p, offset) << p->regshift;
/* Save the LCR value so it can be re-written when a
* Busy Detect interrupt occurs. */
if (save_offset == UART_LCR) {
struct uart_8250_port *up = (struct uart_8250_port *)p;
up->lcr = value;
}
writeb(value, p->membase + offset);
/* Read the IER to ensure any interrupt is cleared before
* returning from ISR. */
if (save_offset == UART_TX || save_offset == UART_IER)
value = p->serial_in(p, UART_IER);
}
static unsigned int io_serial_in(struct uart_port *p, int offset)
{
offset = map_8250_in_reg(p, offset) << p->regshift;
return inb(p->iobase + offset);
}
static void io_serial_out(struct uart_port *p, int offset, int value)
{
offset = map_8250_out_reg(p, offset) << p->regshift;
outb(value, p->iobase + offset);
}
static void set_io_from_upio(struct uart_port *p)
{
struct uart_8250_port *up = (struct uart_8250_port *)p;
switch (p->iotype) {
case UPIO_HUB6:
p->serial_in = hub6_serial_in;
p->serial_out = hub6_serial_out;
break;
case UPIO_MEM:
p->serial_in = mem_serial_in;
p->serial_out = mem_serial_out;
break;
case UPIO_RM9000:
case UPIO_MEM32:
p->serial_in = mem32_serial_in;
p->serial_out = mem32_serial_out;
break;
case UPIO_AU:
p->serial_in = au_serial_in;
p->serial_out = au_serial_out;
break;
case UPIO_TSI:
p->serial_in = tsi_serial_in;
p->serial_out = tsi_serial_out;
break;
case UPIO_DWAPB:
p->serial_in = mem_serial_in;
p->serial_out = dwapb_serial_out;
break;
default:
p->serial_in = io_serial_in;
p->serial_out = io_serial_out;
break;
}
/* Remember loaded iotype */
up->cur_iotype = p->iotype;
}
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
static void
serial_out_sync(struct uart_8250_port *up, int offset, int value)
{
struct uart_port *p = &up->port;
switch (p->iotype) {
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
case UPIO_MEM:
case UPIO_MEM32:
case UPIO_AU:
case UPIO_DWAPB:
p->serial_out(p, offset, value);
p->serial_in(p, UART_LCR); /* safe, no side-effects */
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
break;
default:
p->serial_out(p, offset, value);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
}
}
#define serial_in(up, offset) \
(up->port.serial_in(&(up)->port, (offset)))
#define serial_out(up, offset, value) \
(up->port.serial_out(&(up)->port, (offset), (value)))
/*
* We used to support using pause I/O for certain machines. We
* haven't supported this for a while, but just in case it's badly
* needed for certain old 386 machines, I've left these #define's
* in....
*/
#define serial_inp(up, offset) serial_in(up, offset)
#define serial_outp(up, offset, value) serial_out(up, offset, value)
/* Uart divisor latch read */
static inline int _serial_dl_read(struct uart_8250_port *up)
{
return serial_inp(up, UART_DLL) | serial_inp(up, UART_DLM) << 8;
}
/* Uart divisor latch write */
static inline void _serial_dl_write(struct uart_8250_port *up, int value)
{
serial_outp(up, UART_DLL, value & 0xff);
serial_outp(up, UART_DLM, value >> 8 & 0xff);
}
#if defined(CONFIG_MIPS_ALCHEMY)
/* Au1x00 haven't got a standard divisor latch */
static int serial_dl_read(struct uart_8250_port *up)
{
if (up->port.iotype == UPIO_AU)
return __raw_readl(up->port.membase + 0x28);
else
return _serial_dl_read(up);
}
static void serial_dl_write(struct uart_8250_port *up, int value)
{
if (up->port.iotype == UPIO_AU)
__raw_writel(value, up->port.membase + 0x28);
else
_serial_dl_write(up, value);
}
#elif defined(CONFIG_SERIAL_8250_RM9K)
static int serial_dl_read(struct uart_8250_port *up)
{
return (up->port.iotype == UPIO_RM9000) ?
(((__raw_readl(up->port.membase + 0x10) << 8) |
(__raw_readl(up->port.membase + 0x08) & 0xff)) & 0xffff) :
_serial_dl_read(up);
}
static void serial_dl_write(struct uart_8250_port *up, int value)
{
if (up->port.iotype == UPIO_RM9000) {
__raw_writel(value, up->port.membase + 0x08);
__raw_writel(value >> 8, up->port.membase + 0x10);
} else {
_serial_dl_write(up, value);
}
}
#else
#define serial_dl_read(up) _serial_dl_read(up)
#define serial_dl_write(up, value) _serial_dl_write(up, value)
#endif
/*
* For the 16C950
*/
static void serial_icr_write(struct uart_8250_port *up, int offset, int value)
{
serial_out(up, UART_SCR, offset);
serial_out(up, UART_ICR, value);
}
static unsigned int serial_icr_read(struct uart_8250_port *up, int offset)
{
unsigned int value;
serial_icr_write(up, UART_ACR, up->acr | UART_ACR_ICRRD);
serial_out(up, UART_SCR, offset);
value = serial_in(up, UART_ICR);
serial_icr_write(up, UART_ACR, up->acr);
return value;
}
/*
* FIFO support.
*/
static void serial8250_clear_fifos(struct uart_8250_port *p)
{
if (p->capabilities & UART_CAP_FIFO) {
serial_outp(p, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(p, UART_FCR, UART_FCR_ENABLE_FIFO |
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
serial_outp(p, UART_FCR, 0);
}
}
/*
* IER sleep support. UARTs which have EFRs need the "extended
* capability" bit enabled. Note that on XR16C850s, we need to
* reset LCR to write to IER.
*/
static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
{
if (p->capabilities & UART_CAP_SLEEP) {
if (p->capabilities & UART_CAP_EFR) {
serial_outp(p, UART_LCR, 0xBF);
serial_outp(p, UART_EFR, UART_EFR_ECB);
serial_outp(p, UART_LCR, 0);
}
serial_outp(p, UART_IER, sleep ? UART_IERX_SLEEP : 0);
if (p->capabilities & UART_CAP_EFR) {
serial_outp(p, UART_LCR, 0xBF);
serial_outp(p, UART_EFR, 0);
serial_outp(p, UART_LCR, 0);
}
}
}
#ifdef CONFIG_SERIAL_8250_RSA
/*
* Attempts to turn on the RSA FIFO. Returns zero on failure.
* We set the port uart clock rate if we succeed.
*/
static int __enable_rsa(struct uart_8250_port *up)
{
unsigned char mode;
int result;
mode = serial_inp(up, UART_RSA_MSR);
result = mode & UART_RSA_MSR_FIFO;
if (!result) {
serial_outp(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
mode = serial_inp(up, UART_RSA_MSR);
result = mode & UART_RSA_MSR_FIFO;
}
if (result)
up->port.uartclk = SERIAL_RSA_BAUD_BASE * 16;
return result;
}
static void enable_rsa(struct uart_8250_port *up)
{
if (up->port.type == PORT_RSA) {
if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
spin_lock_irq(&up->port.lock);
__enable_rsa(up);
spin_unlock_irq(&up->port.lock);
}
if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
serial_outp(up, UART_RSA_FRR, 0);
}
}
/*
* Attempts to turn off the RSA FIFO. Returns zero on failure.
* It is unknown why interrupts were disabled in here. However,
* the caller is expected to preserve this behaviour by grabbing
* the spinlock before calling this function.
*/
static void disable_rsa(struct uart_8250_port *up)
{
unsigned char mode;
int result;
if (up->port.type == PORT_RSA &&
up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16) {
spin_lock_irq(&up->port.lock);
mode = serial_inp(up, UART_RSA_MSR);
result = !(mode & UART_RSA_MSR_FIFO);
if (!result) {
serial_outp(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
mode = serial_inp(up, UART_RSA_MSR);
result = !(mode & UART_RSA_MSR_FIFO);
}
if (result)
up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
spin_unlock_irq(&up->port.lock);
}
}
#endif /* CONFIG_SERIAL_8250_RSA */
/*
* This is a quickie test to see how big the FIFO is.
* It doesn't work at all the time, more's the pity.
*/
static int size_fifo(struct uart_8250_port *up)
{
unsigned char old_fcr, old_mcr, old_lcr;
unsigned short old_dl;
int count;
old_lcr = serial_inp(up, UART_LCR);
serial_outp(up, UART_LCR, 0);
old_fcr = serial_inp(up, UART_FCR);
old_mcr = serial_inp(up, UART_MCR);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO |
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
serial_outp(up, UART_MCR, UART_MCR_LOOP);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
old_dl = serial_dl_read(up);
serial_dl_write(up, 0x0001);
serial_outp(up, UART_LCR, 0x03);
for (count = 0; count < 256; count++)
serial_outp(up, UART_TX, count);
mdelay(20);/* FIXME - schedule_timeout */
for (count = 0; (serial_inp(up, UART_LSR) & UART_LSR_DR) &&
(count < 256); count++)
serial_inp(up, UART_RX);
serial_outp(up, UART_FCR, old_fcr);
serial_outp(up, UART_MCR, old_mcr);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
serial_dl_write(up, old_dl);
serial_outp(up, UART_LCR, old_lcr);
return count;
}
/*
* Read UART ID using the divisor method - set DLL and DLM to zero
* and the revision will be in DLL and device type in DLM. We
* preserve the device state across this.
*/
static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
{
unsigned char old_dll, old_dlm, old_lcr;
unsigned int id;
old_lcr = serial_inp(p, UART_LCR);
serial_outp(p, UART_LCR, UART_LCR_DLAB);
old_dll = serial_inp(p, UART_DLL);
old_dlm = serial_inp(p, UART_DLM);
serial_outp(p, UART_DLL, 0);
serial_outp(p, UART_DLM, 0);
id = serial_inp(p, UART_DLL) | serial_inp(p, UART_DLM) << 8;
serial_outp(p, UART_DLL, old_dll);
serial_outp(p, UART_DLM, old_dlm);
serial_outp(p, UART_LCR, old_lcr);
return id;
}
/*
* This is a helper routine to autodetect StarTech/Exar/Oxsemi UART's.
* When this function is called we know it is at least a StarTech
* 16650 V2, but it might be one of several StarTech UARTs, or one of
* its clones. (We treat the broken original StarTech 16650 V1 as a
* 16550, and why not? Startech doesn't seem to even acknowledge its
* existence.)
*
* What evil have men's minds wrought...
*/
static void autoconfig_has_efr(struct uart_8250_port *up)
{
unsigned int id1, id2, id3, rev;
/*
* Everything with an EFR has SLEEP
*/
up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
/*
* First we check to see if it's an Oxford Semiconductor UART.
*
* If we have to do this here because some non-National
* Semiconductor clone chips lock up if you try writing to the
* LSR register (which serial_icr_read does)
*/
/*
* Check for Oxford Semiconductor 16C950.
*
* EFR [4] must be set else this test fails.
*
* This shouldn't be necessary, but Mike Hudson (Exoray@isys.ca)
* claims that it's needed for 952 dual UART's (which are not
* recommended for new designs).
*/
up->acr = 0;
serial_out(up, UART_LCR, 0xBF);
serial_out(up, UART_EFR, UART_EFR_ECB);
serial_out(up, UART_LCR, 0x00);
id1 = serial_icr_read(up, UART_ID1);
id2 = serial_icr_read(up, UART_ID2);
id3 = serial_icr_read(up, UART_ID3);
rev = serial_icr_read(up, UART_REV);
DEBUG_AUTOCONF("950id=%02x:%02x:%02x:%02x ", id1, id2, id3, rev);
if (id1 == 0x16 && id2 == 0xC9 &&
(id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
up->port.type = PORT_16C950;
/*
* Enable work around for the Oxford Semiconductor 952 rev B
* chip which causes it to seriously miscalculate baud rates
* when DLL is 0.
*/
if (id3 == 0x52 && rev == 0x01)
up->bugs |= UART_BUG_QUOT;
return;
}
/*
* We check for a XR16C850 by setting DLL and DLM to 0, and then
* reading back DLL and DLM. The chip type depends on the DLM
* value read back:
* 0x10 - XR16C850 and the DLL contains the chip revision.
* 0x12 - XR16C2850.
* 0x14 - XR16C854.
*/
id1 = autoconfig_read_divisor_id(up);
DEBUG_AUTOCONF("850id=%04x ", id1);
id2 = id1 >> 8;
if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
up->port.type = PORT_16850;
return;
}
/*
* It wasn't an XR16C850.
*
* We distinguish between the '654 and the '650 by counting
* how many bytes are in the FIFO. I'm using this for now,
* since that's the technique that was sent to me in the
* serial driver update, but I'm not convinced this works.
* I've had problems doing this in the past. -TYT
*/
if (size_fifo(up) == 64)
up->port.type = PORT_16654;
else
up->port.type = PORT_16650V2;
}
/*
* We detected a chip without a FIFO. Only two fall into
* this category - the original 8250 and the 16450. The
* 16450 has a scratch register (accessible with LCR=0)
*/
static void autoconfig_8250(struct uart_8250_port *up)
{
unsigned char scratch, status1, status2;
up->port.type = PORT_8250;
scratch = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, 0xa5);
status1 = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, 0x5a);
status2 = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, scratch);
if (status1 == 0xa5 && status2 == 0x5a)
up->port.type = PORT_16450;
}
static int broken_efr(struct uart_8250_port *up)
{
/*
* Exar ST16C2550 "A2" devices incorrectly detect as
* having an EFR, and report an ID of 0x0201. See
* http://www.exar.com/info.php?pdf=dan180_oct2004.pdf
*/
if (autoconfig_read_divisor_id(up) == 0x0201 && size_fifo(up) == 16)
return 1;
return 0;
}
/*
* We know that the chip has FIFOs. Does it have an EFR? The
* EFR is located in the same register position as the IIR and
* we know the top two bits of the IIR are currently set. The
* EFR should contain zero. Try to read the EFR.
*/
static void autoconfig_16550a(struct uart_8250_port *up)
{
unsigned char status1, status2;
unsigned int iersave;
up->port.type = PORT_16550A;
up->capabilities |= UART_CAP_FIFO;
/*
* Check for presence of the EFR when DLAB is set.
* Only ST16C650V1 UARTs pass this test.
*/
serial_outp(up, UART_LCR, UART_LCR_DLAB);
if (serial_in(up, UART_EFR) == 0) {
serial_outp(up, UART_EFR, 0xA8);
if (serial_in(up, UART_EFR) != 0) {
DEBUG_AUTOCONF("EFRv1 ");
up->port.type = PORT_16650;
up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
} else {
DEBUG_AUTOCONF("Motorola 8xxx DUART ");
}
serial_outp(up, UART_EFR, 0);
return;
}
/*
* Maybe it requires 0xbf to be written to the LCR.
* (other ST16C650V2 UARTs, TI16C752A, etc)
*/
serial_outp(up, UART_LCR, 0xBF);
if (serial_in(up, UART_EFR) == 0 && !broken_efr(up)) {
DEBUG_AUTOCONF("EFRv2 ");
autoconfig_has_efr(up);
return;
}
/*
* Check for a National Semiconductor SuperIO chip.
* Attempt to switch to bank 2, read the value of the LOOP bit
* from EXCR1. Switch back to bank 0, change it in MCR. Then
* switch back to bank 2, read it from EXCR1 again and check
* it's changed. If so, set baud_base in EXCR2 to 921600. -- dwmw2
*/
serial_outp(up, UART_LCR, 0);
status1 = serial_in(up, UART_MCR);
serial_outp(up, UART_LCR, 0xE0);
status2 = serial_in(up, 0x02); /* EXCR1 */
if (!((status2 ^ status1) & UART_MCR_LOOP)) {
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_MCR, status1 ^ UART_MCR_LOOP);
serial_outp(up, UART_LCR, 0xE0);
status2 = serial_in(up, 0x02); /* EXCR1 */
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_MCR, status1);
if ((status2 ^ status1) & UART_MCR_LOOP) {
unsigned short quot;
serial_outp(up, UART_LCR, 0xE0);
quot = serial_dl_read(up);
quot <<= 3;
status1 = serial_in(up, 0x04); /* EXCR2 */
status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
status1 |= 0x10; /* 1.625 divisor for baud_base --> 921600 */
serial_outp(up, 0x04, status1);
serial_dl_write(up, quot);
serial_outp(up, UART_LCR, 0);
up->port.uartclk = 921600*16;
up->port.type = PORT_NS16550A;
up->capabilities |= UART_NATSEMI;
return;
}
}
/*
* No EFR. Try to detect a TI16750, which only sets bit 5 of
* the IIR when 64 byte FIFO mode is enabled when DLAB is set.
* Try setting it with and without DLAB set. Cheap clones
* set bit 5 without DLAB set.
*/
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
status1 = serial_in(up, UART_IIR) >> 5;
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
status2 = serial_in(up, UART_IIR) >> 5;
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(up, UART_LCR, 0);
DEBUG_AUTOCONF("iir1=%d iir2=%d ", status1, status2);
if (status1 == 6 && status2 == 7) {
up->port.type = PORT_16750;
up->capabilities |= UART_CAP_AFE | UART_CAP_SLEEP;
return;
}
/*
* Try writing and reading the UART_IER_UUE bit (b6).
* If it works, this is probably one of the Xscale platform's
* internal UARTs.
* We're going to explicitly set the UUE bit to 0 before
* trying to write and read a 1 just to make sure it's not
* already a 1 and maybe locked there before we even start start.
*/
iersave = serial_in(up, UART_IER);
serial_outp(up, UART_IER, iersave & ~UART_IER_UUE);
if (!(serial_in(up, UART_IER) & UART_IER_UUE)) {
/*
* OK it's in a known zero state, try writing and reading
* without disturbing the current state of the other bits.
*/
serial_outp(up, UART_IER, iersave | UART_IER_UUE);
if (serial_in(up, UART_IER) & UART_IER_UUE) {
/*
* It's an Xscale.
* We'll leave the UART_IER_UUE bit set to 1 (enabled).
*/
DEBUG_AUTOCONF("Xscale ");
up->port.type = PORT_XSCALE;
up->capabilities |= UART_CAP_UUE;
return;
}
} else {
/*
* If we got here we couldn't force the IER_UUE bit to 0.
* Log it and continue.
*/
DEBUG_AUTOCONF("Couldn't force IER_UUE to 0 ");
}
serial_outp(up, UART_IER, iersave);
/*
* We distinguish between 16550A and U6 16550A by counting
* how many bytes are in the FIFO.
*/
if (up->port.type == PORT_16550A && size_fifo(up) == 64) {
up->port.type = PORT_U6_16550A;
up->capabilities |= UART_CAP_AFE;
}
}
/*
* This routine is called by rs_init() to initialize a specific serial
* port. It determines what type of UART chip this serial port is
* using: 8250, 16450, 16550, 16550A. The important question is
* whether or not this UART is a 16550A or not, since this will
* determine whether or not we can use its FIFO features or not.
*/
static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
{
unsigned char status1, scratch, scratch2, scratch3;
unsigned char save_lcr, save_mcr;
unsigned long flags;
if (!up->port.iobase && !up->port.mapbase && !up->port.membase)
return;
DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04lx, 0x%p): ",
serial_index(&up->port), up->port.iobase, up->port.membase);
/*
* We really do need global IRQs disabled here - we're going to
* be frobbing the chips IRQ enable register to see if it exists.
*/
spin_lock_irqsave(&up->port.lock, flags);
up->capabilities = 0;
up->bugs = 0;
if (!(up->port.flags & UPF_BUGGY_UART)) {
/*
* Do a simple existence test first; if we fail this,
* there's no point trying anything else.
*
* 0x80 is used as a nonsense port to prevent against
* false positives due to ISA bus float. The
* assumption is that 0x80 is a non-existent port;
* which should be safe since include/asm/io.h also
* makes this assumption.
*
* Note: this is safe as long as MCR bit 4 is clear
* and the device is in "PC" mode.
*/
scratch = serial_inp(up, UART_IER);
serial_outp(up, UART_IER, 0);
#ifdef __i386__
outb(0xff, 0x080);
#endif
/*
* Mask out IER[7:4] bits for test as some UARTs (e.g. TL
* 16C754B) allow only to modify them if an EFR bit is set.
*/
scratch2 = serial_inp(up, UART_IER) & 0x0f;
serial_outp(up, UART_IER, 0x0F);
#ifdef __i386__
outb(0, 0x080);
#endif
scratch3 = serial_inp(up, UART_IER) & 0x0f;
serial_outp(up, UART_IER, scratch);
if (scratch2 != 0 || scratch3 != 0x0F) {
/*
* We failed; there's nothing here
*/
DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",
scratch2, scratch3);
goto out;
}
}
save_mcr = serial_in(up, UART_MCR);
save_lcr = serial_in(up, UART_LCR);
/*
* Check to see if a UART is really there. Certain broken
* internal modems based on the Rockwell chipset fail this
* test, because they apparently don't implement the loopback
* test mode. So this test is skipped on the COM 1 through
* COM 4 ports. This *should* be safe, since no board
* manufacturer would be stupid enough to design a board
* that conflicts with COM 1-4 --- we hope!
*/
if (!(up->port.flags & UPF_SKIP_TEST)) {
serial_outp(up, UART_MCR, UART_MCR_LOOP | 0x0A);
status1 = serial_inp(up, UART_MSR) & 0xF0;
serial_outp(up, UART_MCR, save_mcr);
if (status1 != 0x90) {
DEBUG_AUTOCONF("LOOP test failed (%02x) ",
status1);
goto out;
}
}
/*
* We're pretty sure there's a port here. Lets find out what
* type of port it is. The IIR top two bits allows us to find
* out if it's 8250 or 16450, 16550, 16550A or later. This
* determines what we test for next.
*
* We also initialise the EFR (if any) to zero for later. The
* EFR occupies the same register location as the FCR and IIR.
*/
serial_outp(up, UART_LCR, 0xBF);
serial_outp(up, UART_EFR, 0);
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
scratch = serial_in(up, UART_IIR) >> 6;
DEBUG_AUTOCONF("iir=%d ", scratch);
switch (scratch) {
case 0:
autoconfig_8250(up);
break;
case 1:
up->port.type = PORT_UNKNOWN;
break;
case 2:
up->port.type = PORT_16550;
break;
case 3:
autoconfig_16550a(up);
break;
}
#ifdef CONFIG_SERIAL_8250_RSA
/*
* Only probe for RSA ports if we got the region.
*/
if (up->port.type == PORT_16550A && probeflags & PROBE_RSA) {
int i;
for (i = 0 ; i < probe_rsa_count; ++i) {
if (probe_rsa[i] == up->port.iobase &&
__enable_rsa(up)) {
up->port.type = PORT_RSA;
break;
}
}
}
#endif
serial_outp(up, UART_LCR, save_lcr);
if (up->capabilities != uart_config[up->port.type].flags) {
printk(KERN_WARNING
"ttyS%d: detected caps %08x should be %08x\n",
serial_index(&up->port), up->capabilities,
uart_config[up->port.type].flags);
}
up->port.fifosize = uart_config[up->port.type].fifo_size;
up->capabilities = uart_config[up->port.type].flags;
up->tx_loadsz = uart_config[up->port.type].tx_loadsz;
if (up->port.type == PORT_UNKNOWN)
goto out;
/*
* Reset the UART.
*/
#ifdef CONFIG_SERIAL_8250_RSA
if (up->port.type == PORT_RSA)
serial_outp(up, UART_RSA_FRR, 0);
#endif
serial_outp(up, UART_MCR, save_mcr);
serial8250_clear_fifos(up);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
serial_in(up, UART_RX);
if (up->capabilities & UART_CAP_UUE)
serial_outp(up, UART_IER, UART_IER_UUE);
else
serial_outp(up, UART_IER, 0);
out:
spin_unlock_irqrestore(&up->port.lock, flags);
DEBUG_AUTOCONF("type=%s\n", uart_config[up->port.type].name);
}
static void autoconfig_irq(struct uart_8250_port *up)
{
unsigned char save_mcr, save_ier;
unsigned char save_ICP = 0;
unsigned int ICP = 0;
unsigned long irqs;
int irq;
if (up->port.flags & UPF_FOURPORT) {
ICP = (up->port.iobase & 0xfe0) | 0x1f;
save_ICP = inb_p(ICP);
outb_p(0x80, ICP);
(void) inb_p(ICP);
}
/* forget possible initially masked and pending IRQ */
probe_irq_off(probe_irq_on());
save_mcr = serial_inp(up, UART_MCR);
save_ier = serial_inp(up, UART_IER);
serial_outp(up, UART_MCR, UART_MCR_OUT1 | UART_MCR_OUT2);
irqs = probe_irq_on();
serial_outp(up, UART_MCR, 0);
udelay(10);
if (up->port.flags & UPF_FOURPORT) {
serial_outp(up, UART_MCR,
UART_MCR_DTR | UART_MCR_RTS);
} else {
serial_outp(up, UART_MCR,
UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2);
}
serial_outp(up, UART_IER, 0x0f); /* enable all intrs */
(void)serial_inp(up, UART_LSR);
(void)serial_inp(up, UART_RX);
(void)serial_inp(up, UART_IIR);
(void)serial_inp(up, UART_MSR);
serial_outp(up, UART_TX, 0xFF);
udelay(20);
irq = probe_irq_off(irqs);
serial_outp(up, UART_MCR, save_mcr);
serial_outp(up, UART_IER, save_ier);
if (up->port.flags & UPF_FOURPORT)
outb_p(save_ICP, ICP);
up->port.irq = (irq > 0) ? irq : 0;
}
static inline void __stop_tx(struct uart_8250_port *p)
{
if (p->ier & UART_IER_THRI) {
p->ier &= ~UART_IER_THRI;
serial_out(p, UART_IER, p->ier);
}
}
static void serial8250_stop_tx(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
__stop_tx(up);
/*
* We really want to stop the transmitter from sending.
*/
if (up->port.type == PORT_16C950) {
up->acr |= UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
}
static void transmit_chars(struct uart_8250_port *up);
static void serial8250_start_tx(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
if (!(up->ier & UART_IER_THRI)) {
up->ier |= UART_IER_THRI;
serial_out(up, UART_IER, up->ier);
if (up->bugs & UART_BUG_TXEN) {
unsigned char lsr;
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
if ((up->port.type == PORT_RM9000) ?
(lsr & UART_LSR_THRE) :
(lsr & UART_LSR_TEMT))
transmit_chars(up);
}
}
/*
* Re-enable the transmitter if we disabled it.
*/
if (up->port.type == PORT_16C950 && up->acr & UART_ACR_TXDIS) {
up->acr &= ~UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
}
static void serial8250_stop_rx(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
up->ier &= ~UART_IER_RLSI;
up->port.read_status_mask &= ~UART_LSR_DR;
serial_out(up, UART_IER, up->ier);
}
static void serial8250_enable_ms(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
/* no MSR capabilities */
if (up->bugs & UART_BUG_NOMSR)
return;
up->ier |= UART_IER_MSI;
serial_out(up, UART_IER, up->ier);
}
static void
receive_chars(struct uart_8250_port *up, unsigned int *status)
{
struct tty_struct *tty = up->port.state->port.tty;
unsigned char ch, lsr = *status;
int max_count = 256;
char flag;
do {
if (likely(lsr & UART_LSR_DR))
ch = serial_inp(up, UART_RX);
else
/*
* Intel 82571 has a Serial Over Lan device that will
* set UART_LSR_BI without setting UART_LSR_DR when
* it receives a break. To avoid reading from the
* receive buffer without UART_LSR_DR bit set, we
* just force the read character to be 0
*/
ch = 0;
flag = TTY_NORMAL;
up->port.icount.rx++;
lsr |= up->lsr_saved_flags;
up->lsr_saved_flags = 0;
if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
/*
* For statistics only
*/
if (lsr & UART_LSR_BI) {
lsr &= ~(UART_LSR_FE | UART_LSR_PE);
up->port.icount.brk++;
/*
* We do the SysRQ and SAK checking
* here because otherwise the break
* may get masked by ignore_status_mask
* or read_status_mask.
*/
if (uart_handle_break(&up->port))
goto ignore_char;
} else if (lsr & UART_LSR_PE)
up->port.icount.parity++;
else if (lsr & UART_LSR_FE)
up->port.icount.frame++;
if (lsr & UART_LSR_OE)
up->port.icount.overrun++;
/*
* Mask off conditions which should be ignored.
*/
lsr &= up->port.read_status_mask;
if (lsr & UART_LSR_BI) {
DEBUG_INTR("handling break....");
flag = TTY_BREAK;
} else if (lsr & UART_LSR_PE)
flag = TTY_PARITY;
else if (lsr & UART_LSR_FE)
flag = TTY_FRAME;
}
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
if (uart_handle_sysrq_char(&up->port, ch))
goto ignore_char;
uart_insert_char(&up->port, lsr, UART_LSR_OE, ch, flag);
ignore_char:
lsr = serial_inp(up, UART_LSR);
} while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (max_count-- > 0));
spin_unlock(&up->port.lock);
tty_flip_buffer_push(tty);
spin_lock(&up->port.lock);
*status = lsr;
}
static void transmit_chars(struct uart_8250_port *up)
{
struct circ_buf *xmit = &up->port.state->xmit;
int count;
if (up->port.x_char) {
serial_outp(up, UART_TX, up->port.x_char);
up->port.icount.tx++;
up->port.x_char = 0;
return;
}
if (uart_tx_stopped(&up->port)) {
serial8250_stop_tx(&up->port);
return;
}
if (uart_circ_empty(xmit)) {
__stop_tx(up);
return;
}
count = up->tx_loadsz;
do {
serial_out(up, UART_TX, xmit->buf[xmit->tail]);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
up->port.icount.tx++;
if (uart_circ_empty(xmit))
break;
} while (--count > 0);
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&up->port);
DEBUG_INTR("THRE...");
if (uart_circ_empty(xmit))
__stop_tx(up);
}
static unsigned int check_modem_status(struct uart_8250_port *up)
{
unsigned int status = serial_in(up, UART_MSR);
status |= up->msr_saved_flags;
up->msr_saved_flags = 0;
Fix possible NULL pointer access in 8250 serial driver I encountered the following kernel panic. The cause of this problem was NULL pointer access in check_modem_status() in 8250.c. I confirmed this problem is fixed by the attached patch, but I don't know this is the correct fix. sadc[4378]: NaT consumption 2216203124768 [1] Modules linked in: binfmt_misc dm_mirror dm_mod thermal processor fan container button sg e100 eepro100 mii ehci_hcd ohci_hcd Pid: 4378, CPU 0, comm: sadc psr : 00001210085a2010 ifs : 8000000000000289 ip : [<a000000100482071>] Not tainted ip is at check_modem_status+0xf1/0x360 Call Trace: [<a000000100013940>] show_stack+0x40/0xa0 [<a0000001000145a0>] show_regs+0x840/0x880 [<a0000001000368e0>] die+0x1c0/0x2c0 [<a000000100036a30>] die_if_kernel+0x50/0x80 [<a000000100037c40>] ia64_fault+0x11e0/0x1300 [<a00000010000bdc0>] ia64_leave_kernel+0x0/0x280 [<a000000100482070>] check_modem_status+0xf0/0x360 [<a000000100482300>] serial8250_get_mctrl+0x20/0xa0 [<a000000100478170>] uart_read_proc+0x250/0x860 [<a0000001001c16d0>] proc_file_read+0x1d0/0x4c0 [<a0000001001394b0>] vfs_read+0x1b0/0x300 [<a000000100139cd0>] sys_read+0x70/0xe0 [<a00000010000bc20>] ia64_ret_from_syscall+0x0/0x20 [<a000000000010620>] __kernel_syscall_via_break+0x0/0x20 Fix the possible NULL pointer access in check_modem_status() in 8250.c. The check_modem_status() would access 'info' member of uart_port structure, but it is not initialized before uart_open() is called. The check_modem_status() can be called through /proc/tty/driver/serial before uart_open() is called. Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Taku Izumi <izumi2005@soft.fujitsu.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-23 21:41:00 +00:00
if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI &&
up->port.state != NULL) {
if (status & UART_MSR_TERI)
up->port.icount.rng++;
if (status & UART_MSR_DDSR)
up->port.icount.dsr++;
if (status & UART_MSR_DDCD)
uart_handle_dcd_change(&up->port, status & UART_MSR_DCD);
if (status & UART_MSR_DCTS)
uart_handle_cts_change(&up->port, status & UART_MSR_CTS);
wake_up_interruptible(&up->port.state->port.delta_msr_wait);
}
return status;
}
/*
* This handles the interrupt from one port.
*/
static void serial8250_handle_port(struct uart_8250_port *up)
{
unsigned int status;
unsigned long flags;
spin_lock_irqsave(&up->port.lock, flags);
status = serial_inp(up, UART_LSR);
DEBUG_INTR("status = %x...", status);
if (status & (UART_LSR_DR | UART_LSR_BI))
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
receive_chars(up, &status);
check_modem_status(up);
if (status & UART_LSR_THRE)
transmit_chars(up);
spin_unlock_irqrestore(&up->port.lock, flags);
}
/*
* This is the serial driver's interrupt routine.
*
* Arjan thinks the old way was overly complex, so it got simplified.
* Alan disagrees, saying that need the complexity to handle the weird
* nature of ISA shared interrupts. (This is a special exception.)
*
* In order to handle ISA shared interrupts properly, we need to check
* that all ports have been serviced, and therefore the ISA interrupt
* line has been de-asserted.
*
* This means we need to loop through all ports. checking that they
* don't have an interrupt pending.
*/
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
static irqreturn_t serial8250_interrupt(int irq, void *dev_id)
{
struct irq_info *i = dev_id;
struct list_head *l, *end = NULL;
int pass_counter = 0, handled = 0;
DEBUG_INTR("serial8250_interrupt(%d)...", irq);
spin_lock(&i->lock);
l = i->head;
do {
struct uart_8250_port *up;
unsigned int iir;
up = list_entry(l, struct uart_8250_port, list);
iir = serial_in(up, UART_IIR);
if (!(iir & UART_IIR_NO_INT)) {
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
serial8250_handle_port(up);
handled = 1;
end = NULL;
} else if (up->port.iotype == UPIO_DWAPB &&
(iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
/* The DesignWare APB UART has an Busy Detect (0x07)
* interrupt meaning an LCR write attempt occured while the
* UART was busy. The interrupt must be cleared by reading
* the UART status register (USR) and the LCR re-written. */
unsigned int status;
status = *(volatile u32 *)up->port.private_data;
serial_out(up, UART_LCR, up->lcr);
handled = 1;
end = NULL;
} else if (end == NULL)
end = l;
l = l->next;
if (l == i->head && pass_counter++ > PASS_LIMIT) {
/* If we hit this, we're dead. */
printk(KERN_ERR "serial8250: too much work for "
"irq%d\n", irq);
break;
}
} while (l != end);
spin_unlock(&i->lock);
DEBUG_INTR("end.\n");
return IRQ_RETVAL(handled);
}
/*
* To support ISA shared interrupts, we need to have one interrupt
* handler that ensures that the IRQ line has been deasserted
* before returning. Failing to do this will result in the IRQ
* line being stuck active, and, since ISA irqs are edge triggered,
* no more IRQs will be seen.
*/
static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
{
spin_lock_irq(&i->lock);
if (!list_empty(i->head)) {
if (i->head == &up->list)
i->head = i->head->next;
list_del(&up->list);
} else {
BUG_ON(i->head != &up->list);
i->head = NULL;
}
spin_unlock_irq(&i->lock);
/* List empty so throw away the hash node */
if (i->head == NULL) {
hlist_del(&i->node);
kfree(i);
}
}
static int serial_link_irq_chain(struct uart_8250_port *up)
{
struct hlist_head *h;
struct hlist_node *n;
struct irq_info *i;
int ret, irq_flags = up->port.flags & UPF_SHARE_IRQ ? IRQF_SHARED : 0;
mutex_lock(&hash_mutex);
h = &irq_lists[up->port.irq % NR_IRQ_HASH];
hlist_for_each(n, h) {
i = hlist_entry(n, struct irq_info, node);
if (i->irq == up->port.irq)
break;
}
if (n == NULL) {
i = kzalloc(sizeof(struct irq_info), GFP_KERNEL);
if (i == NULL) {
mutex_unlock(&hash_mutex);
return -ENOMEM;
}
spin_lock_init(&i->lock);
i->irq = up->port.irq;
hlist_add_head(&i->node, h);
}
mutex_unlock(&hash_mutex);
spin_lock_irq(&i->lock);
if (i->head) {
list_add(&up->list, i->head);
spin_unlock_irq(&i->lock);
ret = 0;
} else {
INIT_LIST_HEAD(&up->list);
i->head = &up->list;
spin_unlock_irq(&i->lock);
irq_flags |= up->port.irqflags;
ret = request_irq(up->port.irq, serial8250_interrupt,
irq_flags, "serial", i);
if (ret < 0)
serial_do_unlink(i, up);
}
return ret;
}
static void serial_unlink_irq_chain(struct uart_8250_port *up)
{
struct irq_info *i;
struct hlist_node *n;
struct hlist_head *h;
mutex_lock(&hash_mutex);
h = &irq_lists[up->port.irq % NR_IRQ_HASH];
hlist_for_each(n, h) {
i = hlist_entry(n, struct irq_info, node);
if (i->irq == up->port.irq)
break;
}
BUG_ON(n == NULL);
BUG_ON(i->head == NULL);
if (list_empty(i->head))
free_irq(up->port.irq, i);
serial_do_unlink(i, up);
mutex_unlock(&hash_mutex);
}
/*
* This function is used to handle ports that do not have an
* interrupt. This doesn't work very well for 16450's, but gives
* barely passable results for a 16550A. (Although at the expense
* of much CPU overhead).
*/
static void serial8250_timeout(unsigned long data)
{
struct uart_8250_port *up = (struct uart_8250_port *)data;
unsigned int iir;
iir = serial_in(up, UART_IIR);
if (!(iir & UART_IIR_NO_INT))
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
serial8250_handle_port(up);
mod_timer(&up->timer, jiffies + uart_poll_timeout(&up->port));
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
}
static void serial8250_backup_timeout(unsigned long data)
{
struct uart_8250_port *up = (struct uart_8250_port *)data;
unsigned int iir, ier = 0, lsr;
unsigned long flags;
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
/*
* Must disable interrupts or else we risk racing with the interrupt
* based handler.
*/
if (is_real_interrupt(up->port.irq)) {
ier = serial_in(up, UART_IER);
serial_out(up, UART_IER, 0);
}
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
iir = serial_in(up, UART_IIR);
/*
* This should be a safe test for anyone who doesn't trust the
* IIR bits on their UART, but it's specifically designed for
* the "Diva" UART used on the management processor on many HP
* ia64 and parisc boxes.
*/
spin_lock_irqsave(&up->port.lock, flags);
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
spin_unlock_irqrestore(&up->port.lock, flags);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) &&
(!uart_circ_empty(&up->port.state->xmit) || up->port.x_char) &&
(lsr & UART_LSR_THRE)) {
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
iir &= ~(UART_IIR_ID | UART_IIR_NO_INT);
iir |= UART_IIR_THRI;
}
if (!(iir & UART_IIR_NO_INT))
serial8250_handle_port(up);
if (is_real_interrupt(up->port.irq))
serial_out(up, UART_IER, ier);
/* Standard timer interval plus 0.2s to keep the port running */
mod_timer(&up->timer,
jiffies + uart_poll_timeout(&up->port) + HZ / 5);
}
static unsigned int serial8250_tx_empty(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned long flags;
unsigned int lsr;
spin_lock_irqsave(&up->port.lock, flags);
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
spin_unlock_irqrestore(&up->port.lock, flags);
serial: 8250: add serial transmitter fully empty test When controlling an industrial radio modem it can be necessary to manipulate the handshake lines in order to control the radio modem's transmitter, from userspace. The transmitter should not be turned off before all characters have been transmitted. serial8250_tx_empty() was reporting that all characters were transmitted before they actually were. === Discovered in parallel with more testing and analysis by Kees Schoenmakers as follows: I ran into an NetMos 9835 serial pci board which behaves a little different than the standard. This type of expansion board is very common. "Standard" 8250 compatible devices clear the 'UART_LST_TEMT" bit together with the "UART_LSR_THRE" bit when writing data to the device. The NetMos device does it slightly different I believe that the TEMT bit is coupled to the shift register. The problem is that after writing data to the device and very quickly after that one does call serial8250_tx_empty, it returns the wrong information. My patch makes the test more robust (and solves the problem) and it does not affect the already correct devices. Alan: We may yet need to quirk this but now we know which chips we have a way to do that should we find this breaks some other 8250 clone with dodgy THRE. Signed-off-by: Dick Hollenbeck <dick@softplc.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Cc: Kees Schoenmakers <k.schoenmakers@sigmae.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-09 20:31:34 +00:00
return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0;
}
static unsigned int serial8250_get_mctrl(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned int status;
unsigned int ret;
status = check_modem_status(up);
ret = 0;
if (status & UART_MSR_DCD)
ret |= TIOCM_CAR;
if (status & UART_MSR_RI)
ret |= TIOCM_RNG;
if (status & UART_MSR_DSR)
ret |= TIOCM_DSR;
if (status & UART_MSR_CTS)
ret |= TIOCM_CTS;
return ret;
}
static void serial8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned char mcr = 0;
if (mctrl & TIOCM_RTS)
mcr |= UART_MCR_RTS;
if (mctrl & TIOCM_DTR)
mcr |= UART_MCR_DTR;
if (mctrl & TIOCM_OUT1)
mcr |= UART_MCR_OUT1;
if (mctrl & TIOCM_OUT2)
mcr |= UART_MCR_OUT2;
if (mctrl & TIOCM_LOOP)
mcr |= UART_MCR_LOOP;
mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
serial_out(up, UART_MCR, mcr);
}
static void serial8250_break_ctl(struct uart_port *port, int break_state)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned long flags;
spin_lock_irqsave(&up->port.lock, flags);
if (break_state == -1)
up->lcr |= UART_LCR_SBC;
else
up->lcr &= ~UART_LCR_SBC;
serial_out(up, UART_LCR, up->lcr);
spin_unlock_irqrestore(&up->port.lock, flags);
}
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
/*
* Wait for transmitter & holding register to empty
*/
static void wait_for_xmitr(struct uart_8250_port *up, int bits)
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
{
unsigned int status, tmout = 10000;
/* Wait up to 10ms for the character(s) to be sent. */
for (;;) {
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
status = serial_in(up, UART_LSR);
up->lsr_saved_flags |= status & LSR_SAVE_FLAGS;
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
if ((status & bits) == bits)
break;
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
if (--tmout == 0)
break;
udelay(1);
}
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
/* Wait up to 1s for flow control if necessary */
if (up->port.flags & UPF_CONS_FLOW) {
unsigned int tmout;
for (tmout = 1000000; tmout; tmout--) {
unsigned int msr = serial_in(up, UART_MSR);
up->msr_saved_flags |= msr & MSR_SAVE_FLAGS;
if (msr & UART_MSR_CTS)
break;
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
udelay(1);
touch_nmi_watchdog();
}
}
}
#ifdef CONFIG_CONSOLE_POLL
/*
* Console polling routines for writing and reading from the uart while
* in an interrupt or debug context.
*/
static int serial8250_get_poll_char(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned char lsr = serial_inp(up, UART_LSR);
if (!(lsr & UART_LSR_DR))
return NO_POLL_CHAR;
return serial_inp(up, UART_RX);
}
static void serial8250_put_poll_char(struct uart_port *port,
unsigned char c)
{
unsigned int ier;
struct uart_8250_port *up = (struct uart_8250_port *)port;
/*
* First save the IER then disable the interrupts
*/
ier = serial_in(up, UART_IER);
if (up->capabilities & UART_CAP_UUE)
serial_out(up, UART_IER, UART_IER_UUE);
else
serial_out(up, UART_IER, 0);
wait_for_xmitr(up, BOTH_EMPTY);
/*
* Send the character out.
* If a LF, also do CR...
*/
serial_out(up, UART_TX, c);
if (c == 10) {
wait_for_xmitr(up, BOTH_EMPTY);
serial_out(up, UART_TX, 13);
}
/*
* Finally, wait for transmitter to become empty
* and restore the IER
*/
wait_for_xmitr(up, BOTH_EMPTY);
serial_out(up, UART_IER, ier);
}
#endif /* CONFIG_CONSOLE_POLL */
static int serial8250_startup(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned long flags;
unsigned char lsr, iir;
int retval;
up->capabilities = uart_config[up->port.type].flags;
up->mcr = 0;
if (up->port.iotype != up->cur_iotype)
set_io_from_upio(port);
if (up->port.type == PORT_16C950) {
/* Wake up and initialize UART */
up->acr = 0;
serial_outp(up, UART_LCR, 0xBF);
serial_outp(up, UART_EFR, UART_EFR_ECB);
serial_outp(up, UART_IER, 0);
serial_outp(up, UART_LCR, 0);
serial_icr_write(up, UART_CSR, 0); /* Reset the UART */
serial_outp(up, UART_LCR, 0xBF);
serial_outp(up, UART_EFR, UART_EFR_ECB);
serial_outp(up, UART_LCR, 0);
}
#ifdef CONFIG_SERIAL_8250_RSA
/*
* If this is an RSA port, see if we can kick it up to the
* higher speed clock.
*/
enable_rsa(up);
#endif
/*
* Clear the FIFO buffers and disable them.
* (they will be reenabled in set_termios())
*/
serial8250_clear_fifos(up);
/*
* Clear the interrupt registers.
*/
(void) serial_inp(up, UART_LSR);
(void) serial_inp(up, UART_RX);
(void) serial_inp(up, UART_IIR);
(void) serial_inp(up, UART_MSR);
/*
* At this point, there's no way the LSR could still be 0xff;
* if it is, then bail out, because there's likely no UART
* here.
*/
if (!(up->port.flags & UPF_BUGGY_UART) &&
(serial_inp(up, UART_LSR) == 0xff)) {
printk(KERN_INFO "ttyS%d: LSR safety check engaged!\n",
serial_index(&up->port));
return -ENODEV;
}
/*
* For a XR16C850, we need to set the trigger levels
*/
if (up->port.type == PORT_16850) {
unsigned char fctr;
serial_outp(up, UART_LCR, 0xbf);
fctr = serial_inp(up, UART_FCTR) & ~(UART_FCTR_RX|UART_FCTR_TX);
serial_outp(up, UART_FCTR, fctr | UART_FCTR_TRGD | UART_FCTR_RX);
serial_outp(up, UART_TRG, UART_TRG_96);
serial_outp(up, UART_FCTR, fctr | UART_FCTR_TRGD | UART_FCTR_TX);
serial_outp(up, UART_TRG, UART_TRG_96);
serial_outp(up, UART_LCR, 0);
}
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
if (is_real_interrupt(up->port.irq)) {
unsigned char iir1;
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
/*
* Test for UARTs that do not reassert THRE when the
* transmitter is idle and the interrupt has already
* been cleared. Real 16550s should always reassert
* this interrupt whenever the transmitter is idle and
* the interrupt is enabled. Delays are necessary to
* allow register changes to become visible.
*/
spin_lock_irqsave(&up->port.lock, flags);
if (up->port.irqflags & IRQF_SHARED)
serial: 8250: fix shared interrupts issues with SMP and RT kernels With SMP kernels _irqsave spinlock disables only local interrupts, while the shared serial interrupt could be assigned to the CPU that is not currently starting up the serial port. This might cause issues because serial8250_startup() routine issues IRQ-triggering operations before registering the port in the IRQ chain (though, this is fine to do and done explicitly because we don't want to process any interrupts on the port startup). With RT kernels and preemptable hardirqs, _irqsave spinlock does not disable local hardirqs, and the bug could be reproduced much easily: $ cat /dev/ttyS0 & $ cat /dev/ttyS1 irq 42: nobody cared (try booting with the "irqpoll" option) Call Trace: [C0475EB0] [C0008A98] show_stack+0x4c/0x1ac (unreliable) [C0475EF0] [C004BBD4] __report_bad_irq+0x34/0xb8 [C0475F10] [C004BD38] note_interrupt+0xe0/0x308 [C0475F50] [C004B09C] thread_simple_irq+0xdc/0x104 [C0475F70] [C004B3FC] do_irqd+0x338/0x3c8 [C0475FC0] [C00398E0] kthread+0xf8/0x100 [C0475FF0] [C0011FE0] original_kernel_thread+0x44/0x60 handlers: [<c02112c4>] (serial8250_interrupt+0x0/0x138) Disabling IRQ #42 After this, all serial ports on the given IRQ are non-functional. To fix the issue we should explicitly disable shared IRQ before issuing any IRQ-triggering operations. I also changed spin_lock_irqsave to the ordinary spin_lock, since it seems to be safe: chain does not contain new port (yet), thus nobody will interfere us from the ISRs. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-22 10:21:07 +00:00
disable_irq_nosync(up->port.irq);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
wait_for_xmitr(up, UART_LSR_THRE);
serial_out_sync(up, UART_IER, UART_IER_THRI);
udelay(1); /* allow THRE to set */
iir1 = serial_in(up, UART_IIR);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
serial_out(up, UART_IER, 0);
serial_out_sync(up, UART_IER, UART_IER_THRI);
udelay(1); /* allow a working UART time to re-assert THRE */
iir = serial_in(up, UART_IIR);
serial_out(up, UART_IER, 0);
if (up->port.irqflags & IRQF_SHARED)
serial: 8250: fix shared interrupts issues with SMP and RT kernels With SMP kernels _irqsave spinlock disables only local interrupts, while the shared serial interrupt could be assigned to the CPU that is not currently starting up the serial port. This might cause issues because serial8250_startup() routine issues IRQ-triggering operations before registering the port in the IRQ chain (though, this is fine to do and done explicitly because we don't want to process any interrupts on the port startup). With RT kernels and preemptable hardirqs, _irqsave spinlock does not disable local hardirqs, and the bug could be reproduced much easily: $ cat /dev/ttyS0 & $ cat /dev/ttyS1 irq 42: nobody cared (try booting with the "irqpoll" option) Call Trace: [C0475EB0] [C0008A98] show_stack+0x4c/0x1ac (unreliable) [C0475EF0] [C004BBD4] __report_bad_irq+0x34/0xb8 [C0475F10] [C004BD38] note_interrupt+0xe0/0x308 [C0475F50] [C004B09C] thread_simple_irq+0xdc/0x104 [C0475F70] [C004B3FC] do_irqd+0x338/0x3c8 [C0475FC0] [C00398E0] kthread+0xf8/0x100 [C0475FF0] [C0011FE0] original_kernel_thread+0x44/0x60 handlers: [<c02112c4>] (serial8250_interrupt+0x0/0x138) Disabling IRQ #42 After this, all serial ports on the given IRQ are non-functional. To fix the issue we should explicitly disable shared IRQ before issuing any IRQ-triggering operations. I also changed spin_lock_irqsave to the ordinary spin_lock, since it seems to be safe: chain does not contain new port (yet), thus nobody will interfere us from the ISRs. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-22 10:21:07 +00:00
enable_irq(up->port.irq);
spin_unlock_irqrestore(&up->port.lock, flags);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
/*
* If the interrupt is not reasserted, setup a timer to
* kick the UART on a regular basis.
*/
if (!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) {
up->bugs |= UART_BUG_THRE;
pr_debug("ttyS%d - using backup timer\n",
serial_index(port));
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
}
}
/*
* The above check will only give an accurate result the first time
* the port is opened so this value needs to be preserved.
*/
if (up->bugs & UART_BUG_THRE) {
up->timer.function = serial8250_backup_timeout;
up->timer.data = (unsigned long)up;
mod_timer(&up->timer, jiffies +
uart_poll_timeout(port) + HZ / 5);
}
/*
* If the "interrupt" for this port doesn't correspond with any
* hardware interrupt, we use a timer-based system. The original
* driver used to do this with IRQ0.
*/
if (!is_real_interrupt(up->port.irq)) {
up->timer.data = (unsigned long)up;
mod_timer(&up->timer, jiffies + uart_poll_timeout(port));
} else {
retval = serial_link_irq_chain(up);
if (retval)
return retval;
}
/*
* Now, initialize the UART
*/
serial_outp(up, UART_LCR, UART_LCR_WLEN8);
spin_lock_irqsave(&up->port.lock, flags);
if (up->port.flags & UPF_FOURPORT) {
if (!is_real_interrupt(up->port.irq))
up->port.mctrl |= TIOCM_OUT1;
} else
/*
* Most PC uarts need OUT2 raised to enable interrupts.
*/
if (is_real_interrupt(up->port.irq))
up->port.mctrl |= TIOCM_OUT2;
serial8250_set_mctrl(&up->port, up->port.mctrl);
8250: fix boot hang with serial console when using with Serial Over Lan port Intel 8257x Ethernet boards have a feature called Serial Over Lan. This feature works by emulating a serial port, and it is detected by kernel as a normal 8250 port. However, this emulation is not perfect, as also noticed on changeset 7500b1f602aad75901774a67a687ee985d85893f. Before this patch, the kernel were trying to check if the serial TX is capable of work using IRQ's. This were done with a code similar this: serial_outp(up, UART_IER, UART_IER_THRI); lsr = serial_in(up, UART_LSR); iir = serial_in(up, UART_IIR); serial_outp(up, UART_IER, 0); if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) up->bugs |= UART_BUG_TXEN; This works fine for other 8250 ports, but, on 8250-emulated SoL port, the chip is a little lazy to down UART_IIR_NO_INT at UART_IIR register. Due to that, UART_BUG_TXEN is sometimes enabled. However, as TX IRQ keeps working, and the TX polling is now enabled, the driver miss-interprets the IRQ received later, hanging up the machine until a key is pressed at the serial console. This is the 6 version of this patch. Previous versions were trying to introduce a large enough delay between serial_outp and serial_in(up, UART_IIR), but not taking forever. However, the needed delay couldn't be safely determined. At the experimental tests, a delay of 1us solves most of the cases, but still hangs sometimes. Increasing the delay to 5us was better, but still doesn't solve. A very high delay of 50 ms seemed to work every time. However, poking around with delays and pray for it to be enough doesn't seem to be a good approach, even for a quirk. So, instead of playing with random large arbitrary delays, let's just disable UART_BUG_TXEN for all SoL ports. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-20 23:38:52 +00:00
/* Serial over Lan (SoL) hack:
Intel 8257x Gigabit ethernet chips have a
16550 emulation, to be used for Serial Over Lan.
Those chips take a longer time than a normal
serial device to signalize that a transmission
data was queued. Due to that, the above test generally
fails. One solution would be to delay the reading of
iir. However, this is not reliable, since the timeout
is variable. So, let's just don't test if we receive
TX irq. This way, we'll never enable UART_BUG_TXEN.
*/
if (skip_txen_test || up->port.flags & UPF_NO_TXEN_TEST)
8250: fix boot hang with serial console when using with Serial Over Lan port Intel 8257x Ethernet boards have a feature called Serial Over Lan. This feature works by emulating a serial port, and it is detected by kernel as a normal 8250 port. However, this emulation is not perfect, as also noticed on changeset 7500b1f602aad75901774a67a687ee985d85893f. Before this patch, the kernel were trying to check if the serial TX is capable of work using IRQ's. This were done with a code similar this: serial_outp(up, UART_IER, UART_IER_THRI); lsr = serial_in(up, UART_LSR); iir = serial_in(up, UART_IIR); serial_outp(up, UART_IER, 0); if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) up->bugs |= UART_BUG_TXEN; This works fine for other 8250 ports, but, on 8250-emulated SoL port, the chip is a little lazy to down UART_IIR_NO_INT at UART_IIR register. Due to that, UART_BUG_TXEN is sometimes enabled. However, as TX IRQ keeps working, and the TX polling is now enabled, the driver miss-interprets the IRQ received later, hanging up the machine until a key is pressed at the serial console. This is the 6 version of this patch. Previous versions were trying to introduce a large enough delay between serial_outp and serial_in(up, UART_IIR), but not taking forever. However, the needed delay couldn't be safely determined. At the experimental tests, a delay of 1us solves most of the cases, but still hangs sometimes. Increasing the delay to 5us was better, but still doesn't solve. A very high delay of 50 ms seemed to work every time. However, poking around with delays and pray for it to be enough doesn't seem to be a good approach, even for a quirk. So, instead of playing with random large arbitrary delays, let's just disable UART_BUG_TXEN for all SoL ports. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-20 23:38:52 +00:00
goto dont_test_tx_en;
/*
* Do a quick test to see if we receive an
* interrupt when we enable the TX irq.
*/
serial_outp(up, UART_IER, UART_IER_THRI);
lsr = serial_in(up, UART_LSR);
iir = serial_in(up, UART_IIR);
serial_outp(up, UART_IER, 0);
if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
if (!(up->bugs & UART_BUG_TXEN)) {
up->bugs |= UART_BUG_TXEN;
pr_debug("ttyS%d - enabling bad tx status workarounds\n",
serial_index(port));
}
} else {
up->bugs &= ~UART_BUG_TXEN;
}
8250: fix boot hang with serial console when using with Serial Over Lan port Intel 8257x Ethernet boards have a feature called Serial Over Lan. This feature works by emulating a serial port, and it is detected by kernel as a normal 8250 port. However, this emulation is not perfect, as also noticed on changeset 7500b1f602aad75901774a67a687ee985d85893f. Before this patch, the kernel were trying to check if the serial TX is capable of work using IRQ's. This were done with a code similar this: serial_outp(up, UART_IER, UART_IER_THRI); lsr = serial_in(up, UART_LSR); iir = serial_in(up, UART_IIR); serial_outp(up, UART_IER, 0); if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) up->bugs |= UART_BUG_TXEN; This works fine for other 8250 ports, but, on 8250-emulated SoL port, the chip is a little lazy to down UART_IIR_NO_INT at UART_IIR register. Due to that, UART_BUG_TXEN is sometimes enabled. However, as TX IRQ keeps working, and the TX polling is now enabled, the driver miss-interprets the IRQ received later, hanging up the machine until a key is pressed at the serial console. This is the 6 version of this patch. Previous versions were trying to introduce a large enough delay between serial_outp and serial_in(up, UART_IIR), but not taking forever. However, the needed delay couldn't be safely determined. At the experimental tests, a delay of 1us solves most of the cases, but still hangs sometimes. Increasing the delay to 5us was better, but still doesn't solve. A very high delay of 50 ms seemed to work every time. However, poking around with delays and pray for it to be enough doesn't seem to be a good approach, even for a quirk. So, instead of playing with random large arbitrary delays, let's just disable UART_BUG_TXEN for all SoL ports. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-20 23:38:52 +00:00
dont_test_tx_en:
spin_unlock_irqrestore(&up->port.lock, flags);
/*
* Clear the interrupt registers again for luck, and clear the
* saved flags to avoid getting false values from polling
* routines or the previous session.
*/
serial_inp(up, UART_LSR);
serial_inp(up, UART_RX);
serial_inp(up, UART_IIR);
serial_inp(up, UART_MSR);
up->lsr_saved_flags = 0;
up->msr_saved_flags = 0;
/*
* Finally, enable interrupts. Note: Modem status interrupts
* are set via set_termios(), which will be occurring imminently
* anyway, so we don't enable them here.
*/
up->ier = UART_IER_RLSI | UART_IER_RDI;
serial_outp(up, UART_IER, up->ier);
if (up->port.flags & UPF_FOURPORT) {
unsigned int icp;
/*
* Enable interrupts on the AST Fourport board
*/
icp = (up->port.iobase & 0xfe0) | 0x01f;
outb_p(0x80, icp);
(void) inb_p(icp);
}
return 0;
}
static void serial8250_shutdown(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned long flags;
/*
* Disable interrupts from this port
*/
up->ier = 0;
serial_outp(up, UART_IER, 0);
spin_lock_irqsave(&up->port.lock, flags);
if (up->port.flags & UPF_FOURPORT) {
/* reset interrupts on the AST Fourport board */
inb((up->port.iobase & 0xfe0) | 0x1f);
up->port.mctrl |= TIOCM_OUT1;
} else
up->port.mctrl &= ~TIOCM_OUT2;
serial8250_set_mctrl(&up->port, up->port.mctrl);
spin_unlock_irqrestore(&up->port.lock, flags);
/*
* Disable break condition and FIFOs
*/
serial_out(up, UART_LCR, serial_inp(up, UART_LCR) & ~UART_LCR_SBC);
serial8250_clear_fifos(up);
#ifdef CONFIG_SERIAL_8250_RSA
/*
* Reset the RSA board back to 115kbps compat mode.
*/
disable_rsa(up);
#endif
/*
* Read data port to reset things, and then unlink from
* the IRQ chain.
*/
(void) serial_in(up, UART_RX);
[PATCH] 8250 UART backup timer The patch below works around a minor bug found in the UART of the remote management card used in many HP ia64 and parisc servers (aka the Diva UARTs). The problem is that the UART does not reassert the THRE interrupt if it has been previously cleared and the IIR THRI bit is re-enabled. This can produce a very annoying failure mode when used as a serial console, allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it into working again (ie. an unattended reboot could stall). To solve this problem, a backup timer is introduced that runs alongside the standard interrupt driven mechanism. This timer wakes up periodically, checks for a hang condition and gets characters moving again. This backup mechanism is only enabled if the UART is detected as having this problem, so systems without these UARTs will have no additional overhead. This version of the patch incorporates previous comments from Pavel and removes races in the bug detection code. The test is now done before the irq linking to prevent races with interrupt handler clearing the THRE interrupt. Short delays and syncs are also added to ensure the device is able to update register state before the result is tested. Aristeu says: this was tested on the following HP machines and solved the problem: rx2600, rx2620, rx1600 and rx1620s. hpa says: I have seen this same bug in soft UART IP from "a major vendor." Signed-off-by: Alex Williamson <alex.williamson@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:33:04 +00:00
del_timer_sync(&up->timer);
up->timer.function = serial8250_timeout;
if (is_real_interrupt(up->port.irq))
serial_unlink_irq_chain(up);
}
static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int baud)
{
unsigned int quot;
/*
* Handle magic divisors for baud rates above baud_base on
* SMSC SuperIO chips.
*/
if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
baud == (port->uartclk/4))
quot = 0x8001;
else if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
baud == (port->uartclk/8))
quot = 0x8002;
else
quot = uart_get_divisor(port, baud);
return quot;
}
void
serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned char cval, fcr = 0;
unsigned long flags;
unsigned int baud, quot;
switch (termios->c_cflag & CSIZE) {
case CS5:
cval = UART_LCR_WLEN5;
break;
case CS6:
cval = UART_LCR_WLEN6;
break;
case CS7:
cval = UART_LCR_WLEN7;
break;
default:
case CS8:
cval = UART_LCR_WLEN8;
break;
}
if (termios->c_cflag & CSTOPB)
cval |= UART_LCR_STOP;
if (termios->c_cflag & PARENB)
cval |= UART_LCR_PARITY;
if (!(termios->c_cflag & PARODD))
cval |= UART_LCR_EPAR;
#ifdef CMSPAR
if (termios->c_cflag & CMSPAR)
cval |= UART_LCR_SPAR;
#endif
/*
* Ask the core to calculate the divisor for us.
*/
baud = uart_get_baud_rate(port, termios, old,
port->uartclk / 16 / 0xffff,
port->uartclk / 16);
quot = serial8250_get_divisor(port, baud);
/*
* Oxford Semi 952 rev B workaround
*/
if (up->bugs & UART_BUG_QUOT && (quot & 0xff) == 0)
quot++;
if (up->capabilities & UART_CAP_FIFO && up->port.fifosize > 1) {
if (baud < 2400)
fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
else
fcr = uart_config[up->port.type].fcr;
}
/*
* MCR-based auto flow control. When AFE is enabled, RTS will be
* deasserted when the receive FIFO contains more characters than
* the trigger, or the MCR RTS bit is cleared. In the case where
* the remote UART is not using CTS auto flow control, we must
* have sufficient FIFO entries for the latency of the remote
* UART to respond. IOW, at least 32 bytes of FIFO.
*/
if (up->capabilities & UART_CAP_AFE && up->port.fifosize >= 32) {
up->mcr &= ~UART_MCR_AFE;
if (termios->c_cflag & CRTSCTS)
up->mcr |= UART_MCR_AFE;
}
/*
* Ok, we're now changing the port state. Do it with
* interrupts disabled.
*/
spin_lock_irqsave(&up->port.lock, flags);
/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud);
up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
if (termios->c_iflag & INPCK)
up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
if (termios->c_iflag & (BRKINT | PARMRK))
up->port.read_status_mask |= UART_LSR_BI;
/*
* Characteres to ignore
*/
up->port.ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
up->port.ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
if (termios->c_iflag & IGNBRK) {
up->port.ignore_status_mask |= UART_LSR_BI;
/*
* If we're ignoring parity and break indicators,
* ignore overruns too (for real raw support).
*/
if (termios->c_iflag & IGNPAR)
up->port.ignore_status_mask |= UART_LSR_OE;
}
/*
* ignore all characters if CREAD is not set
*/
if ((termios->c_cflag & CREAD) == 0)
up->port.ignore_status_mask |= UART_LSR_DR;
/*
* CTS flow control flag and modem status interrupts
*/
up->ier &= ~UART_IER_MSI;
if (!(up->bugs & UART_BUG_NOMSR) &&
UART_ENABLE_MS(&up->port, termios->c_cflag))
up->ier |= UART_IER_MSI;
if (up->capabilities & UART_CAP_UUE)
up->ier |= UART_IER_UUE | UART_IER_RTOIE;
serial_out(up, UART_IER, up->ier);
if (up->capabilities & UART_CAP_EFR) {
unsigned char efr = 0;
/*
* TI16C752/Startech hardware flow control. FIXME:
* - TI16C752 requires control thresholds to be set.
* - UART_MCR_RTS is ineffective if auto-RTS mode is enabled.
*/
if (termios->c_cflag & CRTSCTS)
efr |= UART_EFR_CTS;
serial_outp(up, UART_LCR, 0xBF);
serial_outp(up, UART_EFR, efr);
}
#ifdef CONFIG_ARCH_OMAP
/* Workaround to enable 115200 baud on OMAP1510 internal ports */
if (cpu_is_omap1510() && is_omap_port(up)) {
if (baud == 115200) {
quot = 1;
serial_out(up, UART_OMAP_OSC_12M_SEL, 1);
} else
serial_out(up, UART_OMAP_OSC_12M_SEL, 0);
}
#endif
if (up->capabilities & UART_NATSEMI) {
/* Switch to bank 2 not bank 1, to avoid resetting EXCR2 */
serial_outp(up, UART_LCR, 0xe0);
} else {
serial_outp(up, UART_LCR, cval | UART_LCR_DLAB);/* set DLAB */
}
serial_dl_write(up, quot);
/*
* LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
* is written without DLAB set, this mode will be disabled.
*/
if (up->port.type == PORT_16750)
serial_outp(up, UART_FCR, fcr);
serial_outp(up, UART_LCR, cval); /* reset DLAB */
up->lcr = cval; /* Save LCR */
if (up->port.type != PORT_16750) {
if (fcr & UART_FCR_ENABLE_FIFO) {
/* emulated UARTs (Lucent Venus 167x) need two steps */
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
}
serial_outp(up, UART_FCR, fcr); /* set fcr */
}
serial8250_set_mctrl(&up->port, up->port.mctrl);
spin_unlock_irqrestore(&up->port.lock, flags);
/* Don't rewrite B0 */
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
}
EXPORT_SYMBOL(serial8250_do_set_termios);
static void
serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
if (port->set_termios)
port->set_termios(port, termios, old);
else
serial8250_do_set_termios(port, termios, old);
}
static void
serial8250_set_ldisc(struct uart_port *port, int new)
{
if (new == N_PPS) {
port->flags |= UPF_HARDPPS_CD;
serial8250_enable_ms(port);
} else
port->flags &= ~UPF_HARDPPS_CD;
}
void serial8250_do_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate)
{
struct uart_8250_port *p = (struct uart_8250_port *)port;
serial8250_set_sleep(p, state != 0);
}
EXPORT_SYMBOL(serial8250_do_pm);
static void
serial8250_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate)
{
if (port->pm)
port->pm(port, state, oldstate);
else
serial8250_do_pm(port, state, oldstate);
}
static unsigned int serial8250_port_size(struct uart_8250_port *pt)
{
if (pt->port.iotype == UPIO_AU)
return 0x1000;
#ifdef CONFIG_ARCH_OMAP
if (is_omap_port(pt))
return 0x16 << pt->port.regshift;
#endif
return 8 << pt->port.regshift;
}
/*
* Resource handling.
*/
static int serial8250_request_std_resource(struct uart_8250_port *up)
{
unsigned int size = serial8250_port_size(up);
int ret = 0;
switch (up->port.iotype) {
case UPIO_AU:
case UPIO_TSI:
case UPIO_MEM32:
case UPIO_MEM:
case UPIO_DWAPB:
if (!up->port.mapbase)
break;
if (!request_mem_region(up->port.mapbase, size, "serial")) {
ret = -EBUSY;
break;
}
if (up->port.flags & UPF_IOREMAP) {
up->port.membase = ioremap_nocache(up->port.mapbase,
size);
if (!up->port.membase) {
release_mem_region(up->port.mapbase, size);
ret = -ENOMEM;
}
}
break;
case UPIO_HUB6:
case UPIO_PORT:
if (!request_region(up->port.iobase, size, "serial"))
ret = -EBUSY;
break;
}
return ret;
}
static void serial8250_release_std_resource(struct uart_8250_port *up)
{
unsigned int size = serial8250_port_size(up);
switch (up->port.iotype) {
case UPIO_AU:
case UPIO_TSI:
case UPIO_MEM32:
case UPIO_MEM:
case UPIO_DWAPB:
if (!up->port.mapbase)
break;
if (up->port.flags & UPF_IOREMAP) {
iounmap(up->port.membase);
up->port.membase = NULL;
}
release_mem_region(up->port.mapbase, size);
break;
case UPIO_HUB6:
case UPIO_PORT:
release_region(up->port.iobase, size);
break;
}
}
static int serial8250_request_rsa_resource(struct uart_8250_port *up)
{
unsigned long start = UART_RSA_BASE << up->port.regshift;
unsigned int size = 8 << up->port.regshift;
int ret = -EINVAL;
switch (up->port.iotype) {
case UPIO_HUB6:
case UPIO_PORT:
start += up->port.iobase;
if (request_region(start, size, "serial-rsa"))
ret = 0;
else
ret = -EBUSY;
break;
}
return ret;
}
static void serial8250_release_rsa_resource(struct uart_8250_port *up)
{
unsigned long offset = UART_RSA_BASE << up->port.regshift;
unsigned int size = 8 << up->port.regshift;
switch (up->port.iotype) {
case UPIO_HUB6:
case UPIO_PORT:
release_region(up->port.iobase + offset, size);
break;
}
}
static void serial8250_release_port(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
serial8250_release_std_resource(up);
if (up->port.type == PORT_RSA)
serial8250_release_rsa_resource(up);
}
static int serial8250_request_port(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
int ret = 0;
ret = serial8250_request_std_resource(up);
if (ret == 0 && up->port.type == PORT_RSA) {
ret = serial8250_request_rsa_resource(up);
if (ret < 0)
serial8250_release_std_resource(up);
}
return ret;
}
static void serial8250_config_port(struct uart_port *port, int flags)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
int probeflags = PROBE_ANY;
int ret;
/*
* Find the region that we can probe for. This in turn
* tells us whether we can probe for the type of port.
*/
ret = serial8250_request_std_resource(up);
if (ret < 0)
return;
ret = serial8250_request_rsa_resource(up);
if (ret < 0)
probeflags &= ~PROBE_RSA;
if (up->port.iotype != up->cur_iotype)
set_io_from_upio(port);
if (flags & UART_CONFIG_TYPE)
autoconfig(up, probeflags);
/* if access method is AU, it is a 16550 with a quirk */
if (up->port.type == PORT_16550A && up->port.iotype == UPIO_AU)
up->bugs |= UART_BUG_NOMSR;
if (up->port.type != PORT_UNKNOWN && flags & UART_CONFIG_IRQ)
autoconfig_irq(up);
if (up->port.type != PORT_RSA && probeflags & PROBE_RSA)
serial8250_release_rsa_resource(up);
if (up->port.type == PORT_UNKNOWN)
serial8250_release_std_resource(up);
}
static int
serial8250_verify_port(struct uart_port *port, struct serial_struct *ser)
{
if (ser->irq >= nr_irqs || ser->irq < 0 ||
ser->baud_base < 9600 || ser->type < PORT_UNKNOWN ||
ser->type >= ARRAY_SIZE(uart_config) || ser->type == PORT_CIRRUS ||
ser->type == PORT_STARTECH)
return -EINVAL;
return 0;
}
static const char *
serial8250_type(struct uart_port *port)
{
int type = port->type;
if (type >= ARRAY_SIZE(uart_config))
type = 0;
return uart_config[type].name;
}
static struct uart_ops serial8250_pops = {
.tx_empty = serial8250_tx_empty,
.set_mctrl = serial8250_set_mctrl,
.get_mctrl = serial8250_get_mctrl,
.stop_tx = serial8250_stop_tx,
.start_tx = serial8250_start_tx,
.stop_rx = serial8250_stop_rx,
.enable_ms = serial8250_enable_ms,
.break_ctl = serial8250_break_ctl,
.startup = serial8250_startup,
.shutdown = serial8250_shutdown,
.set_termios = serial8250_set_termios,
.set_ldisc = serial8250_set_ldisc,
.pm = serial8250_pm,
.type = serial8250_type,
.release_port = serial8250_release_port,
.request_port = serial8250_request_port,
.config_port = serial8250_config_port,
.verify_port = serial8250_verify_port,
#ifdef CONFIG_CONSOLE_POLL
.poll_get_char = serial8250_get_poll_char,
.poll_put_char = serial8250_put_poll_char,
#endif
};
static struct uart_8250_port serial8250_ports[UART_NR];
static void (*serial8250_isa_config)(int port, struct uart_port *up,
unsigned short *capabilities);
void serial8250_set_isa_configurator(
void (*v)(int port, struct uart_port *up, unsigned short *capabilities))
{
serial8250_isa_config = v;
}
EXPORT_SYMBOL(serial8250_set_isa_configurator);
static void __init serial8250_isa_init_ports(void)
{
struct uart_8250_port *up;
static int first = 1;
int i, irqflag = 0;
if (!first)
return;
first = 0;
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
up->port.line = i;
spin_lock_init(&up->port.lock);
init_timer(&up->timer);
up->timer.function = serial8250_timeout;
/*
* ALPHA_KLUDGE_MCR needs to be killed.
*/
up->mcr_mask = ~ALPHA_KLUDGE_MCR;
up->mcr_force = ALPHA_KLUDGE_MCR;
up->port.ops = &serial8250_pops;
}
if (share_irqs)
irqflag = IRQF_SHARED;
for (i = 0, up = serial8250_ports;
i < ARRAY_SIZE(old_serial_port) && i < nr_uarts;
i++, up++) {
up->port.iobase = old_serial_port[i].port;
up->port.irq = irq_canonicalize(old_serial_port[i].irq);
up->port.irqflags = old_serial_port[i].irqflags;
up->port.uartclk = old_serial_port[i].baud_base * 16;
up->port.flags = old_serial_port[i].flags;
up->port.hub6 = old_serial_port[i].hub6;
up->port.membase = old_serial_port[i].iomem_base;
up->port.iotype = old_serial_port[i].io_type;
up->port.regshift = old_serial_port[i].iomem_reg_shift;
set_io_from_upio(&up->port);
up->port.irqflags |= irqflag;
if (serial8250_isa_config != NULL)
serial8250_isa_config(i, &up->port, &up->capabilities);
}
}
static void
serial8250_init_fixed_type_port(struct uart_8250_port *up, unsigned int type)
{
up->port.type = type;
up->port.fifosize = uart_config[type].fifo_size;
up->capabilities = uart_config[type].flags;
up->tx_loadsz = uart_config[type].tx_loadsz;
}
static void __init
serial8250_register_ports(struct uart_driver *drv, struct device *dev)
{
int i;
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
up->cur_iotype = 0xFF;
}
serial8250_isa_init_ports();
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
up->port.dev = dev;
if (up->port.flags & UPF_FIXED_TYPE)
serial8250_init_fixed_type_port(up, up->port.type);
uart_add_one_port(drv, &up->port);
}
}
#ifdef CONFIG_SERIAL_8250_CONSOLE
static void serial8250_console_putchar(struct uart_port *port, int ch)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
wait_for_xmitr(up, UART_LSR_THRE);
serial_out(up, UART_TX, ch);
}
/*
* Print a string to the serial port trying not to disturb
* any possible real use of the port...
*
* The console_lock must be held when we get here.
*/
static void
serial8250_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_8250_port *up = &serial8250_ports[co->index];
unsigned long flags;
unsigned int ier;
int locked = 1;
touch_nmi_watchdog();
local_irq_save(flags);
if (up->port.sysrq) {
/* serial8250_handle_port() already took the lock */
locked = 0;
} else if (oops_in_progress) {
locked = spin_trylock(&up->port.lock);
} else
spin_lock(&up->port.lock);
/*
* First save the IER then disable the interrupts
*/
ier = serial_in(up, UART_IER);
if (up->capabilities & UART_CAP_UUE)
serial_out(up, UART_IER, UART_IER_UUE);
else
serial_out(up, UART_IER, 0);
uart_console_write(&up->port, s, count, serial8250_console_putchar);
/*
* Finally, wait for transmitter to become empty
* and restore the IER
*/
wait_for_xmitr(up, BOTH_EMPTY);
serial_out(up, UART_IER, ier);
/*
* The receive handling will happen properly because the
* receive ready bit will still be set; it is not cleared
* on read. However, modem control will not, we must
* call it if we have saved something in the saved flags
* while processing with interrupts off.
*/
if (up->msr_saved_flags)
check_modem_status(up);
if (locked)
spin_unlock(&up->port.lock);
local_irq_restore(flags);
}
static int __init serial8250_console_setup(struct console *co, char *options)
{
struct uart_port *port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';
/*
* Check whether an invalid uart number has been specified, and
* if so, search for the first available port that does have
* console support.
*/
if (co->index >= nr_uarts)
co->index = 0;
port = &serial8250_ports[co->index].port;
if (!port->iobase && !port->membase)
return -ENODEV;
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(port, co, baud, parity, bits, flow);
}
static int serial8250_console_early_setup(void)
{
return serial8250_find_port_for_earlycon();
}
static struct console serial8250_console = {
.name = "ttyS",
.write = serial8250_console_write,
.device = uart_console_device,
.setup = serial8250_console_setup,
.early_setup = serial8250_console_early_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &serial8250_reg,
};
static int __init serial8250_console_init(void)
{
if (nr_uarts > UART_NR)
nr_uarts = UART_NR;
serial8250_isa_init_ports();
register_console(&serial8250_console);
return 0;
}
console_initcall(serial8250_console_init);
int serial8250_find_port(struct uart_port *p)
{
int line;
struct uart_port *port;
for (line = 0; line < nr_uarts; line++) {
port = &serial8250_ports[line].port;
if (uart_match_port(p, port))
return line;
}
return -ENODEV;
}
#define SERIAL8250_CONSOLE &serial8250_console
#else
#define SERIAL8250_CONSOLE NULL
#endif
static struct uart_driver serial8250_reg = {
.owner = THIS_MODULE,
.driver_name = "serial",
.dev_name = "ttyS",
.major = TTY_MAJOR,
.minor = 64,
.cons = SERIAL8250_CONSOLE,
};
/*
* early_serial_setup - early registration for 8250 ports
*
* Setup an 8250 port structure prior to console initialisation. Use
* after console initialisation will cause undefined behaviour.
*/
int __init early_serial_setup(struct uart_port *port)
{
struct uart_port *p;
if (port->line >= ARRAY_SIZE(serial8250_ports))
return -ENODEV;
serial8250_isa_init_ports();
p = &serial8250_ports[port->line].port;
p->iobase = port->iobase;
p->membase = port->membase;
p->irq = port->irq;
p->irqflags = port->irqflags;
p->uartclk = port->uartclk;
p->fifosize = port->fifosize;
p->regshift = port->regshift;
p->iotype = port->iotype;
p->flags = port->flags;
p->mapbase = port->mapbase;
p->private_data = port->private_data;
p->type = port->type;
p->line = port->line;
set_io_from_upio(p);
if (port->serial_in)
p->serial_in = port->serial_in;
if (port->serial_out)
p->serial_out = port->serial_out;
return 0;
}
/**
* serial8250_suspend_port - suspend one serial port
* @line: serial line number
*
* Suspend one serial port.
*/
void serial8250_suspend_port(int line)
{
uart_suspend_port(&serial8250_reg, &serial8250_ports[line].port);
}
/**
* serial8250_resume_port - resume one serial port
* @line: serial line number
*
* Resume one serial port.
*/
void serial8250_resume_port(int line)
{
struct uart_8250_port *up = &serial8250_ports[line];
if (up->capabilities & UART_NATSEMI) {
unsigned char tmp;
/* Ensure it's still in high speed mode */
serial_outp(up, UART_LCR, 0xE0);
tmp = serial_in(up, 0x04); /* EXCR2 */
tmp &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
tmp |= 0x10; /* 1.625 divisor for baud_base --> 921600 */
serial_outp(up, 0x04, tmp);
serial_outp(up, UART_LCR, 0);
}
uart_resume_port(&serial8250_reg, &up->port);
}
/*
* Register a set of serial devices attached to a platform device. The
* list is terminated with a zero flags entry, which means we expect
* all entries to have at least UPF_BOOT_AUTOCONF set.
*/
static int __devinit serial8250_probe(struct platform_device *dev)
{
struct plat_serial8250_port *p = dev->dev.platform_data;
struct uart_port port;
int ret, i, irqflag = 0;
memset(&port, 0, sizeof(struct uart_port));
if (share_irqs)
irqflag = IRQF_SHARED;
for (i = 0; p && p->flags != 0; p++, i++) {
port.iobase = p->iobase;
port.membase = p->membase;
port.irq = p->irq;
port.irqflags = p->irqflags;
port.uartclk = p->uartclk;
port.regshift = p->regshift;
port.iotype = p->iotype;
port.flags = p->flags;
port.mapbase = p->mapbase;
port.hub6 = p->hub6;
port.private_data = p->private_data;
port.type = p->type;
port.serial_in = p->serial_in;
port.serial_out = p->serial_out;
port.set_termios = p->set_termios;
port.pm = p->pm;
port.dev = &dev->dev;
port.irqflags |= irqflag;
ret = serial8250_register_port(&port);
if (ret < 0) {
dev_err(&dev->dev, "unable to register port at index %d "
"(IO%lx MEM%llx IRQ%d): %d\n", i,
p->iobase, (unsigned long long)p->mapbase,
p->irq, ret);
}
}
return 0;
}
/*
* Remove serial ports registered against a platform device.
*/
static int __devexit serial8250_remove(struct platform_device *dev)
{
int i;
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
if (up->port.dev == &dev->dev)
serial8250_unregister_port(i);
}
return 0;
}
static int serial8250_suspend(struct platform_device *dev, pm_message_t state)
{
int i;
for (i = 0; i < UART_NR; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)
uart_suspend_port(&serial8250_reg, &up->port);
}
return 0;
}
static int serial8250_resume(struct platform_device *dev)
{
int i;
for (i = 0; i < UART_NR; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)
serial8250_resume_port(i);
}
return 0;
}
static struct platform_driver serial8250_isa_driver = {
.probe = serial8250_probe,
.remove = __devexit_p(serial8250_remove),
.suspend = serial8250_suspend,
.resume = serial8250_resume,
.driver = {
.name = "serial8250",
.owner = THIS_MODULE,
},
};
/*
* This "device" covers _all_ ISA 8250-compatible serial devices listed
* in the table in include/asm/serial.h
*/
static struct platform_device *serial8250_isa_devs;
/*
* serial8250_register_port and serial8250_unregister_port allows for
* 16x50 serial ports to be configured at run-time, to support PCMCIA
* modems and PCI multiport cards.
*/
static DEFINE_MUTEX(serial_mutex);
static struct uart_8250_port *serial8250_find_match_or_unused(struct uart_port *port)
{
int i;
/*
* First, find a port entry which matches.
*/
for (i = 0; i < nr_uarts; i++)
if (uart_match_port(&serial8250_ports[i].port, port))
return &serial8250_ports[i];
/*
* We didn't find a matching entry, so look for the first
* free entry. We look for one which hasn't been previously
* used (indicated by zero iobase).
*/
for (i = 0; i < nr_uarts; i++)
if (serial8250_ports[i].port.type == PORT_UNKNOWN &&
serial8250_ports[i].port.iobase == 0)
return &serial8250_ports[i];
/*
* That also failed. Last resort is to find any entry which
* doesn't have a real port associated with it.
*/
for (i = 0; i < nr_uarts; i++)
if (serial8250_ports[i].port.type == PORT_UNKNOWN)
return &serial8250_ports[i];
return NULL;
}
/**
* serial8250_register_port - register a serial port
* @port: serial port template
*
* Configure the serial port specified by the request. If the
* port exists and is in use, it is hung up and unregistered
* first.
*
* The port is then probed and if necessary the IRQ is autodetected
* If this fails an error is returned.
*
* On success the port is ready to use and the line number is returned.
*/
int serial8250_register_port(struct uart_port *port)
{
struct uart_8250_port *uart;
int ret = -ENOSPC;
if (port->uartclk == 0)
return -EINVAL;
mutex_lock(&serial_mutex);
uart = serial8250_find_match_or_unused(port);
if (uart) {
uart_remove_one_port(&serial8250_reg, &uart->port);
uart->port.iobase = port->iobase;
uart->port.membase = port->membase;
uart->port.irq = port->irq;
uart->port.irqflags = port->irqflags;
uart->port.uartclk = port->uartclk;
uart->port.fifosize = port->fifosize;
uart->port.regshift = port->regshift;
uart->port.iotype = port->iotype;
uart->port.flags = port->flags | UPF_BOOT_AUTOCONF;
uart->port.mapbase = port->mapbase;
uart->port.private_data = port->private_data;
if (port->dev)
uart->port.dev = port->dev;
if (port->flags & UPF_FIXED_TYPE)
serial8250_init_fixed_type_port(uart, port->type);
set_io_from_upio(&uart->port);
/* Possibly override default I/O functions. */
if (port->serial_in)
uart->port.serial_in = port->serial_in;
if (port->serial_out)
uart->port.serial_out = port->serial_out;
/* Possibly override set_termios call */
if (port->set_termios)
uart->port.set_termios = port->set_termios;
if (port->pm)
uart->port.pm = port->pm;
if (serial8250_isa_config != NULL)
serial8250_isa_config(0, &uart->port,
&uart->capabilities);
ret = uart_add_one_port(&serial8250_reg, &uart->port);
if (ret == 0)
ret = uart->port.line;
}
mutex_unlock(&serial_mutex);
return ret;
}
EXPORT_SYMBOL(serial8250_register_port);
/**
* serial8250_unregister_port - remove a 16x50 serial port at runtime
* @line: serial line number
*
* Remove one serial port. This may not be called from interrupt
* context. We hand the port back to the our control.
*/
void serial8250_unregister_port(int line)
{
struct uart_8250_port *uart = &serial8250_ports[line];
mutex_lock(&serial_mutex);
uart_remove_one_port(&serial8250_reg, &uart->port);
if (serial8250_isa_devs) {
uart->port.flags &= ~UPF_BOOT_AUTOCONF;
uart->port.type = PORT_UNKNOWN;
uart->port.dev = &serial8250_isa_devs->dev;
uart_add_one_port(&serial8250_reg, &uart->port);
} else {
uart->port.dev = NULL;
}
mutex_unlock(&serial_mutex);
}
EXPORT_SYMBOL(serial8250_unregister_port);
static int __init serial8250_init(void)
{
int ret;
if (nr_uarts > UART_NR)
nr_uarts = UART_NR;
printk(KERN_INFO "Serial: 8250/16550 driver, "
"%d ports, IRQ sharing %sabled\n", nr_uarts,
share_irqs ? "en" : "dis");
#ifdef CONFIG_SPARC
ret = sunserial_register_minors(&serial8250_reg, UART_NR);
#else
serial8250_reg.nr = UART_NR;
ret = uart_register_driver(&serial8250_reg);
#endif
if (ret)
goto out;
serial8250_isa_devs = platform_device_alloc("serial8250",
PLAT8250_DEV_LEGACY);
if (!serial8250_isa_devs) {
ret = -ENOMEM;
goto unreg_uart_drv;
}
ret = platform_device_add(serial8250_isa_devs);
if (ret)
goto put_dev;
serial8250_register_ports(&serial8250_reg, &serial8250_isa_devs->dev);
ret = platform_driver_register(&serial8250_isa_driver);
if (ret == 0)
goto out;
platform_device_del(serial8250_isa_devs);
put_dev:
platform_device_put(serial8250_isa_devs);
unreg_uart_drv:
#ifdef CONFIG_SPARC
sunserial_unregister_minors(&serial8250_reg, UART_NR);
#else
uart_unregister_driver(&serial8250_reg);
#endif
out:
return ret;
}
static void __exit serial8250_exit(void)
{
struct platform_device *isa_dev = serial8250_isa_devs;
/*
* This tells serial8250_unregister_port() not to re-register
* the ports (thereby making serial8250_isa_driver permanently
* in use.)
*/
serial8250_isa_devs = NULL;
platform_driver_unregister(&serial8250_isa_driver);
platform_device_unregister(isa_dev);
#ifdef CONFIG_SPARC
sunserial_unregister_minors(&serial8250_reg, UART_NR);
#else
uart_unregister_driver(&serial8250_reg);
#endif
}
module_init(serial8250_init);
module_exit(serial8250_exit);
EXPORT_SYMBOL(serial8250_suspend_port);
EXPORT_SYMBOL(serial8250_resume_port);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic 8250/16x50 serial driver");
module_param(share_irqs, uint, 0644);
MODULE_PARM_DESC(share_irqs, "Share IRQs with other non-8250/16x50 devices"
" (unsafe)");
module_param(nr_uarts, uint, 0644);
MODULE_PARM_DESC(nr_uarts, "Maximum number of UARTs supported. (1-" __MODULE_STRING(CONFIG_SERIAL_8250_NR_UARTS) ")");
module_param(skip_txen_test, uint, 0644);
MODULE_PARM_DESC(skip_txen_test, "Skip checking for the TXEN bug at init time");
#ifdef CONFIG_SERIAL_8250_RSA
module_param_array(probe_rsa, ulong, &probe_rsa_count, 0444);
MODULE_PARM_DESC(probe_rsa, "Probe I/O ports for RSA");
#endif
MODULE_ALIAS_CHARDEV_MAJOR(TTY_MAJOR);