linux/drivers/serial/sunhv.c
Roel Kluin 52e3632ea6 serial: fix off by one errors
In zs_console_putchar() occurs:

	if (zs_transmit_drain(zport, irq))
		write_zsdata(zport, ch);

However if in zs_transmit_drain() no empty Tx Buffer occurs, limit reaches
-1 => true, and the write still occurs.

This patch changes postfix to prefix decrements in this and similar
functions to prevent similar mistakes in the future.  This decreases the
iterations with one but the chosen loop count was arbitrary anyway.

In sunhv limit reaches -1, not 0, so the test is off by one.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-22 11:32:23 -07:00

659 lines
13 KiB
C

/* sunhv.c: Serial driver for SUN4V hypervisor console.
*
* Copyright (C) 2006, 2007 David S. Miller (davem@davemloft.net)
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/circ_buf.h>
#include <linux/serial.h>
#include <linux/sysrq.h>
#include <linux/console.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/of_device.h>
#include <asm/hypervisor.h>
#include <asm/spitfire.h>
#include <asm/prom.h>
#include <asm/irq.h>
#if defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/serial_core.h>
#include "suncore.h"
#define CON_BREAK ((long)-1)
#define CON_HUP ((long)-2)
#define IGNORE_BREAK 0x1
#define IGNORE_ALL 0x2
static char *con_write_page;
static char *con_read_page;
static int hung_up = 0;
static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
{
while (!uart_circ_empty(xmit)) {
long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
if (status != HV_EOK)
break;
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
port->icount.tx++;
}
}
static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
{
while (!uart_circ_empty(xmit)) {
unsigned long ra = __pa(xmit->buf + xmit->tail);
unsigned long len, status, sent;
len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
UART_XMIT_SIZE);
status = sun4v_con_write(ra, len, &sent);
if (status != HV_EOK)
break;
xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
port->icount.tx += sent;
}
}
static int receive_chars_getchar(struct uart_port *port, struct tty_struct *tty)
{
int saw_console_brk = 0;
int limit = 10000;
while (limit-- > 0) {
long status;
long c = sun4v_con_getchar(&status);
if (status == HV_EWOULDBLOCK)
break;
if (c == CON_BREAK) {
if (uart_handle_break(port))
continue;
saw_console_brk = 1;
c = 0;
}
if (c == CON_HUP) {
hung_up = 1;
uart_handle_dcd_change(port, 0);
} else if (hung_up) {
hung_up = 0;
uart_handle_dcd_change(port, 1);
}
if (tty == NULL) {
uart_handle_sysrq_char(port, c);
continue;
}
port->icount.rx++;
if (uart_handle_sysrq_char(port, c))
continue;
tty_insert_flip_char(tty, c, TTY_NORMAL);
}
return saw_console_brk;
}
static int receive_chars_read(struct uart_port *port, struct tty_struct *tty)
{
int saw_console_brk = 0;
int limit = 10000;
while (limit-- > 0) {
unsigned long ra = __pa(con_read_page);
unsigned long bytes_read, i;
long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
if (stat != HV_EOK) {
bytes_read = 0;
if (stat == CON_BREAK) {
if (uart_handle_break(port))
continue;
saw_console_brk = 1;
*con_read_page = 0;
bytes_read = 1;
} else if (stat == CON_HUP) {
hung_up = 1;
uart_handle_dcd_change(port, 0);
continue;
} else {
/* HV_EWOULDBLOCK, etc. */
break;
}
}
if (hung_up) {
hung_up = 0;
uart_handle_dcd_change(port, 1);
}
for (i = 0; i < bytes_read; i++)
uart_handle_sysrq_char(port, con_read_page[i]);
if (tty == NULL)
continue;
port->icount.rx += bytes_read;
tty_insert_flip_string(tty, con_read_page, bytes_read);
}
return saw_console_brk;
}
struct sunhv_ops {
void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
int (*receive_chars)(struct uart_port *port, struct tty_struct *tty);
};
static struct sunhv_ops bychar_ops = {
.transmit_chars = transmit_chars_putchar,
.receive_chars = receive_chars_getchar,
};
static struct sunhv_ops bywrite_ops = {
.transmit_chars = transmit_chars_write,
.receive_chars = receive_chars_read,
};
static struct sunhv_ops *sunhv_ops = &bychar_ops;
static struct tty_struct *receive_chars(struct uart_port *port)
{
struct tty_struct *tty = NULL;
if (port->info != NULL) /* Unopened serial console */
tty = port->info->port.tty;
if (sunhv_ops->receive_chars(port, tty))
sun_do_break();
return tty;
}
static void transmit_chars(struct uart_port *port)
{
struct circ_buf *xmit;
if (!port->info)
return;
xmit = &port->info->xmit;
if (uart_circ_empty(xmit) || uart_tx_stopped(port))
return;
sunhv_ops->transmit_chars(port, xmit);
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
}
static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
struct tty_struct *tty;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
tty = receive_chars(port);
transmit_chars(port);
spin_unlock_irqrestore(&port->lock, flags);
if (tty)
tty_flip_buffer_push(tty);
return IRQ_HANDLED;
}
/* port->lock is not held. */
static unsigned int sunhv_tx_empty(struct uart_port *port)
{
/* Transmitter is always empty for us. If the circ buffer
* is non-empty or there is an x_char pending, our caller
* will do the right thing and ignore what we return here.
*/
return TIOCSER_TEMT;
}
/* port->lock held by caller. */
static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
return;
}
/* port->lock is held by caller and interrupts are disabled. */
static unsigned int sunhv_get_mctrl(struct uart_port *port)
{
return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
}
/* port->lock held by caller. */
static void sunhv_stop_tx(struct uart_port *port)
{
return;
}
/* port->lock held by caller. */
static void sunhv_start_tx(struct uart_port *port)
{
transmit_chars(port);
}
/* port->lock is not held. */
static void sunhv_send_xchar(struct uart_port *port, char ch)
{
unsigned long flags;
int limit = 10000;
spin_lock_irqsave(&port->lock, flags);
while (limit-- > 0) {
long status = sun4v_con_putchar(ch);
if (status == HV_EOK)
break;
udelay(1);
}
spin_unlock_irqrestore(&port->lock, flags);
}
/* port->lock held by caller. */
static void sunhv_stop_rx(struct uart_port *port)
{
}
/* port->lock held by caller. */
static void sunhv_enable_ms(struct uart_port *port)
{
}
/* port->lock is not held. */
static void sunhv_break_ctl(struct uart_port *port, int break_state)
{
if (break_state) {
unsigned long flags;
int limit = 10000;
spin_lock_irqsave(&port->lock, flags);
while (limit-- > 0) {
long status = sun4v_con_putchar(CON_BREAK);
if (status == HV_EOK)
break;
udelay(1);
}
spin_unlock_irqrestore(&port->lock, flags);
}
}
/* port->lock is not held. */
static int sunhv_startup(struct uart_port *port)
{
return 0;
}
/* port->lock is not held. */
static void sunhv_shutdown(struct uart_port *port)
{
}
/* port->lock is not held. */
static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
unsigned int quot = uart_get_divisor(port, baud);
unsigned int iflag, cflag;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
iflag = termios->c_iflag;
cflag = termios->c_cflag;
port->ignore_status_mask = 0;
if (iflag & IGNBRK)
port->ignore_status_mask |= IGNORE_BREAK;
if ((cflag & CREAD) == 0)
port->ignore_status_mask |= IGNORE_ALL;
/* XXX */
uart_update_timeout(port, cflag,
(port->uartclk / (16 * quot)));
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *sunhv_type(struct uart_port *port)
{
return "SUN4V HCONS";
}
static void sunhv_release_port(struct uart_port *port)
{
}
static int sunhv_request_port(struct uart_port *port)
{
return 0;
}
static void sunhv_config_port(struct uart_port *port, int flags)
{
}
static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
{
return -EINVAL;
}
static struct uart_ops sunhv_pops = {
.tx_empty = sunhv_tx_empty,
.set_mctrl = sunhv_set_mctrl,
.get_mctrl = sunhv_get_mctrl,
.stop_tx = sunhv_stop_tx,
.start_tx = sunhv_start_tx,
.send_xchar = sunhv_send_xchar,
.stop_rx = sunhv_stop_rx,
.enable_ms = sunhv_enable_ms,
.break_ctl = sunhv_break_ctl,
.startup = sunhv_startup,
.shutdown = sunhv_shutdown,
.set_termios = sunhv_set_termios,
.type = sunhv_type,
.release_port = sunhv_release_port,
.request_port = sunhv_request_port,
.config_port = sunhv_config_port,
.verify_port = sunhv_verify_port,
};
static struct uart_driver sunhv_reg = {
.owner = THIS_MODULE,
.driver_name = "sunhv",
.dev_name = "ttyS",
.major = TTY_MAJOR,
};
static struct uart_port *sunhv_port;
/* Copy 's' into the con_write_page, decoding "\n" into
* "\r\n" along the way. We have to return two lengths
* because the caller needs to know how much to advance
* 's' and also how many bytes to output via con_write_page.
*/
static int fill_con_write_page(const char *s, unsigned int n,
unsigned long *page_bytes)
{
const char *orig_s = s;
char *p = con_write_page;
int left = PAGE_SIZE;
while (n--) {
if (*s == '\n') {
if (left < 2)
break;
*p++ = '\r';
left--;
} else if (left < 1)
break;
*p++ = *s++;
left--;
}
*page_bytes = p - con_write_page;
return s - orig_s;
}
static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
{
struct uart_port *port = sunhv_port;
unsigned long flags;
int locked = 1;
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
} else if (oops_in_progress) {
locked = spin_trylock(&port->lock);
} else
spin_lock(&port->lock);
while (n > 0) {
unsigned long ra = __pa(con_write_page);
unsigned long page_bytes;
unsigned int cpy = fill_con_write_page(s, n,
&page_bytes);
n -= cpy;
s += cpy;
while (page_bytes > 0) {
unsigned long written;
int limit = 1000000;
while (limit--) {
unsigned long stat;
stat = sun4v_con_write(ra, page_bytes,
&written);
if (stat == HV_EOK)
break;
udelay(1);
}
if (limit < 0)
break;
page_bytes -= written;
ra += written;
}
}
if (locked)
spin_unlock(&port->lock);
local_irq_restore(flags);
}
static inline void sunhv_console_putchar(struct uart_port *port, char c)
{
int limit = 1000000;
while (limit-- > 0) {
long status = sun4v_con_putchar(c);
if (status == HV_EOK)
break;
udelay(1);
}
}
static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
{
struct uart_port *port = sunhv_port;
unsigned long flags;
int i, locked = 1;
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
} else if (oops_in_progress) {
locked = spin_trylock(&port->lock);
} else
spin_lock(&port->lock);
for (i = 0; i < n; i++) {
if (*s == '\n')
sunhv_console_putchar(port, '\r');
sunhv_console_putchar(port, *s++);
}
if (locked)
spin_unlock(&port->lock);
local_irq_restore(flags);
}
static struct console sunhv_console = {
.name = "ttyHV",
.write = sunhv_console_write_bychar,
.device = uart_console_device,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &sunhv_reg,
};
static int __devinit hv_probe(struct of_device *op, const struct of_device_id *match)
{
struct uart_port *port;
unsigned long minor;
int err;
if (op->irqs[0] == 0xffffffff)
return -ENODEV;
port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
if (unlikely(!port))
return -ENOMEM;
minor = 1;
if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
minor >= 1) {
err = -ENOMEM;
con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!con_write_page)
goto out_free_port;
con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!con_read_page)
goto out_free_con_write_page;
sunhv_console.write = sunhv_console_write_paged;
sunhv_ops = &bywrite_ops;
}
sunhv_port = port;
port->line = 0;
port->ops = &sunhv_pops;
port->type = PORT_SUNHV;
port->uartclk = ( 29491200 / 16 ); /* arbitrary */
port->membase = (unsigned char __iomem *) __pa(port);
port->irq = op->irqs[0];
port->dev = &op->dev;
err = sunserial_register_minors(&sunhv_reg, 1);
if (err)
goto out_free_con_read_page;
sunserial_console_match(&sunhv_console, op->node,
&sunhv_reg, port->line);
err = uart_add_one_port(&sunhv_reg, port);
if (err)
goto out_unregister_driver;
err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
if (err)
goto out_remove_port;
dev_set_drvdata(&op->dev, port);
return 0;
out_remove_port:
uart_remove_one_port(&sunhv_reg, port);
out_unregister_driver:
sunserial_unregister_minors(&sunhv_reg, 1);
out_free_con_read_page:
kfree(con_read_page);
out_free_con_write_page:
kfree(con_write_page);
out_free_port:
kfree(port);
sunhv_port = NULL;
return err;
}
static int __devexit hv_remove(struct of_device *dev)
{
struct uart_port *port = dev_get_drvdata(&dev->dev);
free_irq(port->irq, port);
uart_remove_one_port(&sunhv_reg, port);
sunserial_unregister_minors(&sunhv_reg, 1);
kfree(port);
sunhv_port = NULL;
dev_set_drvdata(&dev->dev, NULL);
return 0;
}
static const struct of_device_id hv_match[] = {
{
.name = "console",
.compatible = "qcn",
},
{
.name = "console",
.compatible = "SUNW,sun4v-console",
},
{},
};
MODULE_DEVICE_TABLE(of, hv_match);
static struct of_platform_driver hv_driver = {
.name = "hv",
.match_table = hv_match,
.probe = hv_probe,
.remove = __devexit_p(hv_remove),
};
static int __init sunhv_init(void)
{
if (tlb_type != hypervisor)
return -ENODEV;
return of_register_driver(&hv_driver, &of_bus_type);
}
static void __exit sunhv_exit(void)
{
of_unregister_driver(&hv_driver);
}
module_init(sunhv_init);
module_exit(sunhv_exit);
MODULE_AUTHOR("David S. Miller");
MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
MODULE_VERSION("2.0");
MODULE_LICENSE("GPL");