linux/arch/sh/kernel/sh_bios.c
Paul Mundt 94cd049522 sh: sh_bios detection.
This adds some VBR sanity checks in the sh_bios code to ensure that the
BIOS VBR is in range before blindly trapping in to it. This permits
boards with varying boot loader configurations to always leave support
for sh-bios enabled and it will just be disabled at run-time if not
found.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-01-12 18:42:52 +09:00

172 lines
3.9 KiB
C

/*
* C interface for trapping into the standard LinuxSH BIOS.
*
* Copyright (C) 2000 Greg Banks, Mitch Davis
* Copyright (C) 1999, 2000 Niibe Yutaka
* Copyright (C) 2002 M. R. Brown
* Copyright (C) 2004 - 2010 Paul Mundt
*
* 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/module.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <asm/sh_bios.h>
#define BIOS_CALL_CONSOLE_WRITE 0
#define BIOS_CALL_ETH_NODE_ADDR 10
#define BIOS_CALL_SHUTDOWN 11
#define BIOS_CALL_GDB_DETACH 0xff
void *gdb_vbr_vector = NULL;
static inline long sh_bios_call(long func, long arg0, long arg1, long arg2,
long arg3)
{
register long r0 __asm__("r0") = func;
register long r4 __asm__("r4") = arg0;
register long r5 __asm__("r5") = arg1;
register long r6 __asm__("r6") = arg2;
register long r7 __asm__("r7") = arg3;
if (!gdb_vbr_vector)
return -ENOSYS;
__asm__ __volatile__("trapa #0x3f":"=z"(r0)
:"0"(r0), "r"(r4), "r"(r5), "r"(r6), "r"(r7)
:"memory");
return r0;
}
void sh_bios_console_write(const char *buf, unsigned int len)
{
sh_bios_call(BIOS_CALL_CONSOLE_WRITE, (long)buf, (long)len, 0, 0);
}
void sh_bios_gdb_detach(void)
{
sh_bios_call(BIOS_CALL_GDB_DETACH, 0, 0, 0, 0);
}
EXPORT_SYMBOL_GPL(sh_bios_gdb_detach);
void sh_bios_get_node_addr(unsigned char *node_addr)
{
sh_bios_call(BIOS_CALL_ETH_NODE_ADDR, 0, (long)node_addr, 0, 0);
}
EXPORT_SYMBOL_GPL(sh_bios_get_node_addr);
void sh_bios_shutdown(unsigned int how)
{
sh_bios_call(BIOS_CALL_SHUTDOWN, how, 0, 0, 0);
}
/*
* Read the old value of the VBR register to initialise the vector
* through which debug and BIOS traps are delegated by the Linux trap
* handler.
*/
void sh_bios_vbr_init(void)
{
unsigned long vbr;
if (unlikely(gdb_vbr_vector))
return;
__asm__ __volatile__ ("stc vbr, %0" : "=r" (vbr));
if (vbr) {
gdb_vbr_vector = (void *)(vbr + 0x100);
printk(KERN_NOTICE "Setting GDB trap vector to %p\n",
gdb_vbr_vector);
} else
printk(KERN_NOTICE "SH-BIOS not detected\n");
}
/**
* sh_bios_vbr_reload - Re-load the system VBR from the BIOS vector.
*
* This can be used by save/restore code to reinitialize the system VBR
* from the fixed BIOS VBR. A no-op if no BIOS VBR is known.
*/
void sh_bios_vbr_reload(void)
{
if (gdb_vbr_vector)
__asm__ __volatile__ (
"ldc %0, vbr"
:
: "r" (((unsigned long) gdb_vbr_vector) - 0x100)
: "memory"
);
}
/*
* Print a string through the BIOS
*/
static void sh_console_write(struct console *co, const char *s,
unsigned count)
{
sh_bios_console_write(s, count);
}
/*
* Setup initial baud/bits/parity. We do two things here:
* - construct a cflag setting for the first rs_open()
* - initialize the serial port
* Return non-zero if we didn't find a serial port.
*/
static int __init sh_console_setup(struct console *co, char *options)
{
int cflag = CREAD | HUPCL | CLOCAL;
/*
* Now construct a cflag setting.
* TODO: this is a totally bogus cflag, as we have
* no idea what serial settings the BIOS is using, or
* even if its using the serial port at all.
*/
cflag |= B115200 | CS8 | /*no parity*/0;
co->cflag = cflag;
return 0;
}
static struct console bios_console = {
.name = "bios",
.write = sh_console_write,
.setup = sh_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
};
static struct console *early_console;
static int __init setup_early_printk(char *buf)
{
int keep_early = 0;
if (!buf)
return 0;
if (strstr(buf, "keep"))
keep_early = 1;
if (!strncmp(buf, "bios", 4))
early_console = &bios_console;
if (likely(early_console)) {
if (keep_early)
early_console->flags &= ~CON_BOOT;
else
early_console->flags |= CON_BOOT;
register_console(early_console);
}
return 0;
}
early_param("earlyprintk", setup_early_printk);