root/arch/x86/kernel/acpi/realmode/wakemain.c

DEFINITIONS

1. udelay
2. beep
3. send_morse
4. main

#include "wakeup.h"
#include "boot.h"

static void udelay(int loops)
{
        while (loops--)
                io_delay();     /* Approximately 1 us */
}

static void beep(unsigned int hz)
{
        u8 enable;

        if (!hz) {
                enable = 0x00;          /* Turn off speaker */
        } else {
                u16 div = 1193181/hz;

                outb(0xb6, 0x43);       /* Ctr 2, squarewave, load, binary */
                io_delay();
                outb(div, 0x42);        /* LSB of counter */
                io_delay();
                outb(div >> 8, 0x42);   /* MSB of counter */
                io_delay();

                enable = 0x03;          /* Turn on speaker */
        }
        inb(0x61);              /* Dummy read of System Control Port B */
        io_delay();
        outb(enable, 0x61);     /* Enable timer 2 output to speaker */
        io_delay();
}

#define DOT_HZ          880
#define DASH_HZ         587
#define US_PER_DOT      125000

/* Okay, this is totally silly, but it's kind of fun. */
static void send_morse(const char *pattern)
{
        char s;

        while ((s = *pattern++)) {
                switch (s) {
                case '.':
                        beep(DOT_HZ);
                        udelay(US_PER_DOT);
                        beep(0);
                        udelay(US_PER_DOT);
                        break;
                case '-':
                        beep(DASH_HZ);
                        udelay(US_PER_DOT * 3);
                        beep(0);
                        udelay(US_PER_DOT);
                        break;
                default:        /* Assume it's a space */
                        udelay(US_PER_DOT * 3);
                        break;
                }
        }
}

void main(void)
{
        /* Kill machine if structures are wrong */
        if (wakeup_header.real_magic != 0x12345678)
                while (1);

        if (wakeup_header.realmode_flags & 4)
                send_morse("...-");

        if (wakeup_header.realmode_flags & 1)
                asm volatile("lcallw   $0xc000,$3");

        if (wakeup_header.realmode_flags & 2) {
                /* Need to call BIOS */
                probe_cards(0);
                set_mode(wakeup_header.video_mode);
        }
}