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x86, earlyprintk: Add hsu early console for Intel Medfield platform

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Intel Medfield platform has a high speed UART device, which
could act as a early console. To enable early printk of HSU
console, simply add "earlyprintk=hsu" in kernel command line.

Currently we put the code in the early_printk_mrst.c as it is
also for Intel MID platforms like the mrst early console

Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Cc: greg@kroah.com
LKML-Reference: <1284361736-23011-5-git-send-email-feng.tang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Feng Tang 2010-09-13 15:08:56 +08:00 committed by Ingo Molnar
parent c20b5c3318
commit 4d033556f1
3 changed files with 97 additions and 1 deletions
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3
arch/x86/include/asm/mrst.h
View File

@ -47,4 +47,7 @@ extern enum mrst_timer_options mrst_timer_options;
extern struct console early_mrst_console;
extern void mrst_early_console_init(void);
extern struct console early_hsu_console;
extern void hsu_early_console_init(void);
#endif /* _ASM_X86_MRST_H */

6
arch/x86/kernel/early_printk.c
View File

@ -245,6 +245,12 @@ static int __init setup_early_printk(char *buf)
mrst_early_console_init();
early_console_register(&early_mrst_console, keep);
}
if (!strncmp(buf, "hsu", 3)) {
hsu_early_console_init();
early_console_register(&early_hsu_console, keep);
}
#endif
buf++;
}

89
arch/x86/kernel/early_printk_mrst.c
View File

@ -1,5 +1,5 @@
/*
* early_printk_mrst.c - spi-uart early printk for Intel Moorestown platform
* early_printk_mrst.c - early consoles for Intel MID platforms
*
* Copyright (c) 2008-2010, Intel Corporation
*
@ -9,9 +9,19 @@
* of the License.
*/
/*
* This file implements two early consoles named mrst and hsu.
* mrst is based on Maxim3110 spi-uart device, it exists in both
* Moorestown and Medfield platforms, while hsu is based on a High
* Speed UART device which only exists in the Medfield platform
*/
#include <linux/serial_reg.h>
#include <linux/serial_mfd.h>
#include <linux/kmsg_dump.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
@ -230,3 +240,80 @@ struct console early_mrst_console = {
.flags = CON_PRINTBUFFER,
.index = -1,
};
/*
* Following is the early console based on Medfield HSU (High
* Speed UART) device.
*/
#define HSU_PORT2_PADDR 0xffa28180
static void __iomem *phsu;
void hsu_early_console_init(void)
{
u8 lcr;
phsu = (void *)set_fixmap_offset_nocache(FIX_EARLYCON_MEM_BASE,
HSU_PORT2_PADDR);
/* Disable FIFO */
writeb(0x0, phsu + UART_FCR);
/* Set to default 115200 bps, 8n1 */
lcr = readb(phsu + UART_LCR);
writeb((0x80 | lcr), phsu + UART_LCR);
writeb(0x18, phsu + UART_DLL);
writeb(lcr, phsu + UART_LCR);
writel(0x3600, phsu + UART_MUL*4);
writeb(0x8, phsu + UART_MCR);
writeb(0x7, phsu + UART_FCR);
writeb(0x3, phsu + UART_LCR);
/* Clear IRQ status */
readb(phsu + UART_LSR);
readb(phsu + UART_RX);
readb(phsu + UART_IIR);
readb(phsu + UART_MSR);
/* Enable FIFO */
writeb(0x7, phsu + UART_FCR);
}
#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
static void early_hsu_putc(char ch)
{
unsigned int timeout = 10000; /* 10ms */
u8 status;
while (--timeout) {
status = readb(phsu + UART_LSR);
if (status & BOTH_EMPTY)
break;
udelay(1);
}
/* Only write the char when there was no timeout */
if (timeout)
writeb(ch, phsu + UART_TX);
}
static void early_hsu_write(struct console *con, const char *str, unsigned n)
{
int i;
for (i = 0; i < n && *str; i++) {
if (*str == '\n')
early_hsu_putc('\r');
early_hsu_putc(*str);
str++;
}
}
struct console early_hsu_console = {
.name = "earlyhsu",
.write = early_hsu_write,
.flags = CON_PRINTBUFFER,
.index = -1,
};