sh_bios.c

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/*
 *  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");
}

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);