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microblaze_v8: early_printk support

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Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: John Linn <john.linn@xilinx.com>
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
This commit is contained in:
Michal Simek 2009-03-27 14:25:22 +01:00
parent f11e044b44
commit 89272a51b3
1 changed files with 107 additions and 0 deletions
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107
arch/microblaze/kernel/early_printk.c Normal file
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/*
* Early printk support for Microblaze.
*
* Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2007-2009 PetaLogix
* Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/tty.h>
#include <linux/io.h>
#include <asm/processor.h>
#include <linux/fcntl.h>
#include <asm/setup.h>
#include <asm/prom.h>
static u32 early_console_initialized;
static u32 base_addr;
static void early_printk_putc(char c)
{
/*
* Limit how many times we'll spin waiting for TX FIFO status.
* This will prevent lockups if the base address is incorrectly
* set, or any other issue on the UARTLITE.
* This limit is pretty arbitrary, unless we are at about 10 baud
* we'll never timeout on a working UART.
*/
unsigned retries = 10000;
/* read status bit - 0x8 offset */
while (retries-- && (in_be32(base_addr + 8) & (1 << 3)))
;
/* Only attempt the iowrite if we didn't timeout */
/* write to TX_FIFO - 0x4 offset */
if (retries)
out_be32(base_addr + 4, c & 0xff);
}
static void early_printk_write(struct console *unused,
const char *s, unsigned n)
{
while (*s && n-- > 0) {
early_printk_putc(*s);
if (*s == '\n')
early_printk_putc('\r');
s++;
}
}
static struct console early_serial_console = {
.name = "earlyser",
.write = early_printk_write,
.flags = CON_PRINTBUFFER,
.index = -1,
};
static struct console *early_console = &early_serial_console;
void early_printk(const char *fmt, ...)
{
char buf[512];
int n;
va_list ap;
if (early_console_initialized) {
va_start(ap, fmt);
n = vscnprintf(buf, 512, fmt, ap);
early_console->write(early_console, buf, n);
va_end(ap);
}
}
int __init setup_early_printk(char *opt)
{
if (early_console_initialized)
return 1;
base_addr = early_uartlite_console();
if (base_addr) {
early_console_initialized = 1;
early_printk("early_printk_console is enabled at 0x%08x\n",
base_addr);
/* register_console(early_console); */
return 0;
} else
return 1;
}
void __init disable_early_printk(void)
{
if (!early_console_initialized || !early_console)
return;
printk(KERN_WARNING "disabling early console\n");
unregister_console(early_console);
early_console_initialized = 0;
}