// SPDX-License-Identifier: GPL-2.0
/*
 *  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
 */
#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"
                );
}

#ifdef CONFIG_EARLY_PRINTK
/*
 *      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 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);
#endif