LXR linux/arch/x86/boot/video-mode.c

   1/* -*- linux-c -*- ------------------------------------------------------- *
   2 *
   3 *   Copyright (C) 1991, 1992 Linus Torvalds
   4 *   Copyright 2007-2008 rPath, Inc. - All Rights Reserved
   5 *
   6 *   This file is part of the Linux kernel, and is made available under
   7 *   the terms of the GNU General Public License version 2.
   8 *
   9 * ----------------------------------------------------------------------- */
  10
  11/*
  12 * arch/i386/boot/video-mode.c
  13 *
  14 * Set the video mode.  This is separated out into a different
  15 * file in order to be shared with the ACPI wakeup code.
  16 */
  17
  18#include "boot.h"
  19#include "video.h"
  20#include "vesa.h"
  21
  22#include <uapi/asm/boot.h>
  23
  24/*
  25 * Common variables
  26 */
  27int adapter;            /* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
  28int force_x, force_y;   /* Don't query the BIOS for cols/rows */
  29int do_restore;         /* Screen contents changed during mode flip */
  30int graphic_mode;       /* Graphic mode with linear frame buffer */
  31
  32/* Probe the video drivers and have them generate their mode lists. */
  33void probe_cards(int unsafe)
  34{
  35        struct card_info *card;
  36        static u8 probed[2];
  37
  38        if (probed[unsafe])
  39                return;
  40
  41        probed[unsafe] = 1;
  42
  43        for (card = video_cards; card < video_cards_end; card++) {
  44                if (card->unsafe == unsafe) {
  45                        if (card->probe)
  46                                card->nmodes = card->probe();
  47                        else
  48                                card->nmodes = 0;
  49                }
  50        }
  51}
  52
  53/* Test if a mode is defined */
  54int mode_defined(u16 mode)
  55{
  56        struct card_info *card;
  57        struct mode_info *mi;
  58        int i;
  59
  60        for (card = video_cards; card < video_cards_end; card++) {
  61                mi = card->modes;
  62                for (i = 0; i < card->nmodes; i++, mi++) {
  63                        if (mi->mode == mode)
  64                                return 1;
  65                }
  66        }
  67
  68        return 0;
  69}
  70
  71/* Set mode (without recalc) */
  72static int raw_set_mode(u16 mode, u16 *real_mode)
  73{
  74        int nmode, i;
  75        struct card_info *card;
  76        struct mode_info *mi;
  77
  78        /* Drop the recalc bit if set */
  79        mode &= ~VIDEO_RECALC;
  80
  81        /* Scan for mode based on fixed ID, position, or resolution */
  82        nmode = 0;
  83        for (card = video_cards; card < video_cards_end; card++) {
  84                mi = card->modes;
  85                for (i = 0; i < card->nmodes; i++, mi++) {
  86                        int visible = mi->x || mi->y;
  87
  88                        if ((mode == nmode && visible) ||
  89                            mode == mi->mode ||
  90                            mode == (mi->y << 8)+mi->x) {
  91                                *real_mode = mi->mode;
  92                                return card->set_mode(mi);
  93                        }
  94
  95                        if (visible)
  96                                nmode++;
  97                }
  98        }
  99
 100        /* Nothing found?  Is it an "exceptional" (unprobed) mode? */
 101        for (card = video_cards; card < video_cards_end; card++) {
 102                if (mode >= card->xmode_first &&
 103                    mode < card->xmode_first+card->xmode_n) {
 104                        struct mode_info mix;
 105                        *real_mode = mix.mode = mode;
 106                        mix.x = mix.y = 0;
 107                        return card->set_mode(&mix);
 108                }
 109        }
 110
 111        /* Otherwise, failure... */
 112        return -1;
 113}
 114
 115/*
 116 * Recalculate the vertical video cutoff (hack!)
 117 */
 118static void vga_recalc_vertical(void)
 119{
 120        unsigned int font_size, rows;
 121        u16 crtc;
 122        u8 pt, ov;
 123
 124        set_fs(0);
 125        font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
 126        rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
 127
 128        rows *= font_size;      /* Visible scan lines */
 129        rows--;                 /* ... minus one */
 130
 131        crtc = vga_crtc();
 132
 133        pt = in_idx(crtc, 0x11);
 134        pt &= ~0x80;            /* Unlock CR0-7 */
 135        out_idx(pt, crtc, 0x11);
 136
 137        out_idx((u8)rows, crtc, 0x12); /* Lower height register */
 138
 139        ov = in_idx(crtc, 0x07); /* Overflow register */
 140        ov &= 0xbd;
 141        ov |= (rows >> (8-1)) & 0x02;
 142        ov |= (rows >> (9-6)) & 0x40;
 143        out_idx(ov, crtc, 0x07);
 144}
 145
 146/* Set mode (with recalc if specified) */
 147int set_mode(u16 mode)
 148{
 149        int rv;
 150        u16 real_mode;
 151
 152        /* Very special mode numbers... */
 153        if (mode == VIDEO_CURRENT_MODE)
 154                return 0;       /* Nothing to do... */
 155        else if (mode == NORMAL_VGA)
 156                mode = VIDEO_80x25;
 157        else if (mode == EXTENDED_VGA)
 158                mode = VIDEO_8POINT;
 159
 160        rv = raw_set_mode(mode, &real_mode);
 161        if (rv)
 162                return rv;
 163
 164        if (mode & VIDEO_RECALC)
 165                vga_recalc_vertical();
 166
 167        /* Save the canonical mode number for the kernel, not
 168           an alias, size specification or menu position */
 169#ifndef _WAKEUP
 170        boot_params.hdr.vid_mode = real_mode;
 171#endif
 172        return 0;
 173}
 174