arch/x86/realmode/rm/wakemain.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "wakeup.h"
   3 #include "boot.h"
   4
   5 static void udelay(int loops)
   6 {
   7         while (loops--)
   8                 io_delay();     /* Approximately 1 us */
   9 }
  10
  11 static void beep(unsigned int hz)
  12 {
  13         u8 enable;
  14
  15         if (!hz) {
  16                 enable = 0x00;          /* Turn off speaker */
  17         } else {
  18                 u16 div = 1193181/hz;
  19
  20                 outb(0xb6, 0x43);       /* Ctr 2, squarewave, load, binary */
  21                 io_delay();
  22                 outb(div, 0x42);        /* LSB of counter */
  23                 io_delay();
  24                 outb(div >> 8, 0x42);   /* MSB of counter */
  25                 io_delay();
  26
  27                 enable = 0x03;          /* Turn on speaker */
  28         }
  29         inb(0x61);              /* Dummy read of System Control Port B */
  30         io_delay();
  31         outb(enable, 0x61);     /* Enable timer 2 output to speaker */
  32         io_delay();
  33 }
  34
  35 #define DOT_HZ          880
  36 #define DASH_HZ         587
  37 #define US_PER_DOT      125000
  38
  39 /* Okay, this is totally silly, but it's kind of fun. */
  40 static void send_morse(const char *pattern)
  41 {
  42         char s;
  43
  44         while ((s = *pattern++)) {
  45                 switch (s) {
  46                 case '.':
  47                         beep(DOT_HZ);
  48                         udelay(US_PER_DOT);
  49                         beep(0);
  50                         udelay(US_PER_DOT);
  51                         break;
  52                 case '-':
  53                         beep(DASH_HZ);
  54                         udelay(US_PER_DOT * 3);
  55                         beep(0);
  56                         udelay(US_PER_DOT);
  57                         break;
  58                 default:        /* Assume it's a space */
  59                         udelay(US_PER_DOT * 3);
  60                         break;
  61                 }
  62         }
  63 }
  64
  65 void main(void)
  66 {
  67         /* Kill machine if structures are wrong */
  68         if (wakeup_header.real_magic != 0x12345678)
  69                 while (1)
  70                         ;
  71
  72         if (wakeup_header.realmode_flags & 4)
  73                 send_morse("...-");
  74
  75         if (wakeup_header.realmode_flags & 1)
  76                 asm volatile("lcallw   $0xc000,$3");
  77
  78         if (wakeup_header.realmode_flags & 2) {
  79                 /* Need to call BIOS */
  80                 probe_cards(0);
  81                 set_mode(wakeup_header.video_mode);
  82         }
  83 }