LXR linux/arch/sh/kernel/sh

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  C interface for trapping into the standard LinuxSH BIOS.
   4 *
   5 *  Copyright (C) 2000 Greg Banks, Mitch Davis
   6 *  Copyright (C) 1999, 2000  Niibe Yutaka
   7 *  Copyright (C) 2002  M. R. Brown
   8 *  Copyright (C) 2004 - 2010  Paul Mundt
   9 */
  10#include <linux/module.h>
  11#include <linux/console.h>
  12#include <linux/tty.h>
  13#include <linux/init.h>
  14#include <linux/io.h>
  15#include <linux/delay.h>
  16#include <asm/sh_bios.h>
  17
  18#define BIOS_CALL_CONSOLE_WRITE         0
  19#define BIOS_CALL_ETH_NODE_ADDR         10
  20#define BIOS_CALL_SHUTDOWN              11
  21#define BIOS_CALL_GDB_DETACH            0xff
  22
  23void *gdb_vbr_vector = NULL;
  24
  25static inline long sh_bios_call(long func, long arg0, long arg1, long arg2,
  26                                    long arg3)
  27{
  28        register long r0 __asm__("r0") = func;
  29        register long r4 __asm__("r4") = arg0;
  30        register long r5 __asm__("r5") = arg1;
  31        register long r6 __asm__("r6") = arg2;
  32        register long r7 __asm__("r7") = arg3;
  33
  34        if (!gdb_vbr_vector)
  35                return -ENOSYS;
  36
  37        __asm__ __volatile__("trapa     #0x3f":"=z"(r0)
  38                             :"0"(r0), "r"(r4), "r"(r5), "r"(r6), "r"(r7)
  39                             :"memory");
  40        return r0;
  41}
  42
  43void sh_bios_console_write(const char *buf, unsigned int len)
  44{
  45        sh_bios_call(BIOS_CALL_CONSOLE_WRITE, (long)buf, (long)len, 0, 0);
  46}
  47
  48void sh_bios_gdb_detach(void)
  49{
  50        sh_bios_call(BIOS_CALL_GDB_DETACH, 0, 0, 0, 0);
  51}
  52EXPORT_SYMBOL_GPL(sh_bios_gdb_detach);
  53
  54void sh_bios_get_node_addr(unsigned char *node_addr)
  55{
  56        sh_bios_call(BIOS_CALL_ETH_NODE_ADDR, 0, (long)node_addr, 0, 0);
  57}
  58EXPORT_SYMBOL_GPL(sh_bios_get_node_addr);
  59
  60void sh_bios_shutdown(unsigned int how)
  61{
  62        sh_bios_call(BIOS_CALL_SHUTDOWN, how, 0, 0, 0);
  63}
  64
  65/*
  66 * Read the old value of the VBR register to initialise the vector
  67 * through which debug and BIOS traps are delegated by the Linux trap
  68 * handler.
  69 */
  70void sh_bios_vbr_init(void)
  71{
  72        unsigned long vbr;
  73
  74        if (unlikely(gdb_vbr_vector))
  75                return;
  76
  77        __asm__ __volatile__ ("stc vbr, %0" : "=r" (vbr));
  78
  79        if (vbr) {
  80                gdb_vbr_vector = (void *)(vbr + 0x100);
  81                printk(KERN_NOTICE "Setting GDB trap vector to %p\n",
  82                       gdb_vbr_vector);
  83        } else
  84                printk(KERN_NOTICE "SH-BIOS not detected\n");
  85}
  86
  87/**
  88 * sh_bios_vbr_reload - Re-load the system VBR from the BIOS vector.
  89 *
  90 * This can be used by save/restore code to reinitialize the system VBR
  91 * from the fixed BIOS VBR. A no-op if no BIOS VBR is known.
  92 */
  93void sh_bios_vbr_reload(void)
  94{
  95        if (gdb_vbr_vector)
  96                __asm__ __volatile__ (
  97                        "ldc %0, vbr"
  98                        :
  99                        : "r" (((unsigned long) gdb_vbr_vector) - 0x100)
 100                        : "memory"
 101                );
 102}
 103
 104#ifdef CONFIG_EARLY_PRINTK
 105/*
 106 *      Print a string through the BIOS
 107 */
 108static void sh_console_write(struct console *co, const char *s,
 109                                 unsigned count)
 110{
 111        sh_bios_console_write(s, count);
 112}
 113
 114/*
 115 *      Setup initial baud/bits/parity. We do two things here:
 116 *      - construct a cflag setting for the first rs_open()
 117 *      - initialize the serial port
 118 *      Return non-zero if we didn't find a serial port.
 119 */
 120static int __init sh_console_setup(struct console *co, char *options)
 121{
 122        int     cflag = CREAD | HUPCL | CLOCAL;
 123
 124        /*
 125         *      Now construct a cflag setting.
 126         *      TODO: this is a totally bogus cflag, as we have
 127         *      no idea what serial settings the BIOS is using, or
 128         *      even if its using the serial port at all.
 129         */
 130        cflag |= B115200 | CS8 | /*no parity*/0;
 131
 132        co->cflag = cflag;
 133
 134        return 0;
 135}
 136
 137static struct console bios_console = {
 138        .name           = "bios",
 139        .write          = sh_console_write,
 140        .setup          = sh_console_setup,
 141        .flags          = CON_PRINTBUFFER,
 142        .index          = -1,
 143};
 144
 145static int __init setup_early_printk(char *buf)
 146{
 147        int keep_early = 0;
 148
 149        if (!buf)
 150                return 0;
 151
 152        if (strstr(buf, "keep"))
 153                keep_early = 1;
 154
 155        if (!strncmp(buf, "bios", 4))
 156                early_console = &bios_console;
 157
 158        if (likely(early_console)) {
 159                if (keep_early)
 160                        early_console->flags &= ~CON_BOOT;
 161                else
 162                        early_console->flags |= CON_BOOT;
 163                register_console(early_console);
 164        }
 165
 166        return 0;
 167}
 168early_param("earlyprintk", setup_early_printk);
 169#endif
 170