arch/sh/kernel/sh_bios.c

   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
  23 void *gdb_vbr_vector = NULL;
  24
  25 static 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
  43 void 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
  48 void sh_bios_gdb_detach(void)
  49 {
  50         sh_bios_call(BIOS_CALL_GDB_DETACH, 0, 0, 0, 0);
  51 }
  52 EXPORT_SYMBOL_GPL(sh_bios_gdb_detach);
  53
  54 void 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 }
  58 EXPORT_SYMBOL_GPL(sh_bios_get_node_addr);
  59
  60 void 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  */
  70 void 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  */
  93 void 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  */
 108 static 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  */
 120 static 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
 137 static 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
 145 static 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 }
 168 early_param("earlyprintk", setup_early_printk);
 169 #endif