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 /*
  23  * Common variables
  24  */
  25 int adapter;                    /* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
  26 u16 video_segment;
  27 int force_x, force_y;   /* Don't query the BIOS for cols/rows */
  28
  29 int do_restore;         /* Screen contents changed during mode flip */
  30 int graphic_mode;       /* Graphic mode with linear frame buffer */
  31
  32 /* Probe the video drivers and have them generate their mode lists. */
  33 void 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 */
  54 int 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) */
  72 static 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  */
 118 static 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) */
 147 int 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 }