video-mode.c
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/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007-2008 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-mode.c
*
* Set the video mode. This is separated out into a different
* file in order to be shared with the ACPI wakeup code.
*/
#include "boot.h"
#include "video.h"
#include "vesa.h"
/*
* Common variables
*/
int adapter; /* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
u16 video_segment;
int force_x, force_y; /* Don't query the BIOS for cols/rows */
int do_restore; /* Screen contents changed during mode flip */
int graphic_mode; /* Graphic mode with linear frame buffer */
/* Probe the video drivers and have them generate their mode lists. */
void probe_cards(int unsafe)
{
struct card_info *card;
static u8 probed[2];
if (probed[unsafe])
return;
probed[unsafe] = 1;
for (card = video_cards; card < video_cards_end; card++) {
if (card->unsafe == unsafe) {
if (card->probe)
card->nmodes = card->probe();
else
card->nmodes = 0;
}
}
}
/* Test if a mode is defined */
int mode_defined(u16 mode)
{
struct card_info *card;
struct mode_info *mi;
int i;
for (card = video_cards; card < video_cards_end; card++) {
mi = card->modes;
for (i = 0; i < card->nmodes; i++, mi++) {
if (mi->mode == mode)
return 1;
}
}
return 0;
}
/* Set mode (without recalc) */
static int raw_set_mode(u16 mode, u16 *real_mode)
{
int nmode, i;
struct card_info *card;
struct mode_info *mi;
/* Drop the recalc bit if set */
mode &= ~VIDEO_RECALC;
/* Scan for mode based on fixed ID, position, or resolution */
nmode = 0;
for (card = video_cards; card < video_cards_end; card++) {
mi = card->modes;
for (i = 0; i < card->nmodes; i++, mi++) {
int visible = mi->x || mi->y;
if ((mode == nmode && visible) ||
mode == mi->mode ||
mode == (mi->y << 8)+mi->x) {
*real_mode = mi->mode;
return card->set_mode(mi);
}
if (visible)
nmode++;
}
}
/* Nothing found? Is it an "exceptional" (unprobed) mode? */
for (card = video_cards; card < video_cards_end; card++) {
if (mode >= card->xmode_first &&
mode < card->xmode_first+card->xmode_n) {
struct mode_info mix;
*real_mode = mix.mode = mode;
mix.x = mix.y = 0;
return card->set_mode(&mix);
}
}
/* Otherwise, failure... */
return -1;
}
/*
* Recalculate the vertical video cutoff (hack!)
*/
static void vga_recalc_vertical(void)
{
unsigned int font_size, rows;
u16 crtc;
u8 pt, ov;
set_fs(0);
font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
rows *= font_size; /* Visible scan lines */
rows--; /* ... minus one */
crtc = vga_crtc();
pt = in_idx(crtc, 0x11);
pt &= ~0x80; /* Unlock CR0-7 */
out_idx(pt, crtc, 0x11);
out_idx((u8)rows, crtc, 0x12); /* Lower height register */
ov = in_idx(crtc, 0x07); /* Overflow register */
ov &= 0xbd;
ov |= (rows >> (8-1)) & 0x02;
ov |= (rows >> (9-6)) & 0x40;
out_idx(ov, crtc, 0x07);
}
/* Set mode (with recalc if specified) */
int set_mode(u16 mode)
{
int rv;
u16 real_mode;
/* Very special mode numbers... */
if (mode == VIDEO_CURRENT_MODE)
return 0; /* Nothing to do... */
else if (mode == NORMAL_VGA)
mode = VIDEO_80x25;
else if (mode == EXTENDED_VGA)
mode = VIDEO_8POINT;
rv = raw_set_mode(mode, &real_mode);
if (rv)
return rv;
if (mode & VIDEO_RECALC)
vga_recalc_vertical();
/* Save the canonical mode number for the kernel, not
an alias, size specification or menu position */
#ifndef _WAKEUP
boot_params.hdr.vid_mode = real_mode;
#endif
return 0;
}