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/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/video-bios.c
*
* Standard video BIOS modes
*
* We have two options for this; silent and scanned.
*/
#include "boot.h"
#include "video.h"
__videocard video_bios;
/* Set a conventional BIOS mode */
static int set_bios_mode(u8 mode);
static int bios_set_mode(struct mode_info *mi)
{
return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS);
}
static int set_bios_mode(u8 mode)
{
u16 ax;
u8 new_mode;
ax = mode; /* AH=0x00 Set Video Mode */
asm volatile(INT10
: "+a" (ax)
: : "ebx", "ecx", "edx", "esi", "edi");
ax = 0x0f00; /* Get Current Video Mode */
asm volatile(INT10
: "+a" (ax)
: : "ebx", "ecx", "edx", "esi", "edi");
do_restore = 1; /* Assume video contents was lost */
new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */
if (new_mode == mode)
return 0; /* Mode change OK */
if (new_mode != boot_params.screen_info.orig_video_mode) {
/* Mode setting failed, but we didn't end up where we
started. That's bad. Try to revert to the original
video mode. */
ax = boot_params.screen_info.orig_video_mode;
asm volatile(INT10
: "+a" (ax)
: : "ebx", "ecx", "edx", "esi", "edi");
}
return -1;
}
static int bios_probe(void)
{
u8 mode;
u8 saved_mode = boot_params.screen_info.orig_video_mode;
u16 crtc;
struct mode_info *mi;
int nmodes = 0;
if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA)
return 0;
set_fs(0);
crtc = vga_crtc();
video_bios.modes = GET_HEAP(struct mode_info, 0);
for (mode = 0x14; mode <= 0x7f; mode++) {
if (heap_free() < sizeof(struct mode_info))
break;
if (mode_defined(VIDEO_FIRST_BIOS+mode))
continue;
if (set_bios_mode(mode))
continue;
/* Try to verify that it's a text mode. */
/* Attribute Controller: make graphics controller disabled */
if (in_idx(0x3c0, 0x10) & 0x01)
continue;
/* Graphics Controller: verify Alpha addressing enabled */
if (in_idx(0x3ce, 0x06) & 0x01)
continue;
/* CRTC cursor location low should be zero(?) */
if (in_idx(crtc, 0x0f))
continue;
mi = GET_HEAP(struct mode_info, 1);
mi->mode = VIDEO_FIRST_BIOS+mode;
mi->x = rdfs16(0x44a);
mi->y = rdfs8(0x484)+1;
nmodes++;
}
set_bios_mode(saved_mode);
return nmodes;
}
__videocard video_bios =
{
.card_name = "BIOS (scanned)",
.probe = bios_probe,
.set_mode = bios_set_mode,
.unsafe = 1,
.xmode_first = VIDEO_FIRST_BIOS,
.xmode_n = 0x80,
};
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