arch/x86/boot/video-vga.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* -*- linux-c -*- ------------------------------------------------------- *
   3  *
   4  *   Copyright (C) 1991, 1992 Linus Torvalds
   5  *   Copyright 2007 rPath, Inc. - All Rights Reserved
   6  *   Copyright 2009 Intel Corporation; author H. Peter Anvin
   7  *
   8  * ----------------------------------------------------------------------- */
   9
  10 /*
  11  * Common all-VGA modes
  12  */
  13
  14 #include "boot.h"
  15 #include "video.h"
  16
  17 static struct mode_info vga_modes[] = {
  18         { VIDEO_80x25,  80, 25, 0 },
  19         { VIDEO_8POINT, 80, 50, 0 },
  20         { VIDEO_80x43,  80, 43, 0 },
  21         { VIDEO_80x28,  80, 28, 0 },
  22         { VIDEO_80x30,  80, 30, 0 },
  23         { VIDEO_80x34,  80, 34, 0 },
  24         { VIDEO_80x60,  80, 60, 0 },
  25 };
  26
  27 static struct mode_info ega_modes[] = {
  28         { VIDEO_80x25,  80, 25, 0 },
  29         { VIDEO_8POINT, 80, 43, 0 },
  30 };
  31
  32 static struct mode_info cga_modes[] = {
  33         { VIDEO_80x25,  80, 25, 0 },
  34 };
  35
  36 static __videocard video_vga;
  37
  38 /* Set basic 80x25 mode */
  39 static u8 vga_set_basic_mode(void)
  40 {
  41         struct biosregs ireg, oreg;
  42         u8 mode;
  43
  44         initregs(&ireg);
  45
  46         /* Query current mode */
  47         ireg.ax = 0x0f00;
  48         intcall(0x10, &ireg, &oreg);
  49         mode = oreg.al;
  50
  51         if (mode != 3 && mode != 7)
  52                 mode = 3;
  53
  54         /* Set the mode */
  55         ireg.ax = mode;         /* AH=0: set mode */
  56         intcall(0x10, &ireg, NULL);
  57         do_restore = 1;
  58         return mode;
  59 }
  60
  61 static void vga_set_8font(void)
  62 {
  63         /* Set 8x8 font - 80x43 on EGA, 80x50 on VGA */
  64         struct biosregs ireg;
  65
  66         initregs(&ireg);
  67
  68         /* Set 8x8 font */
  69         ireg.ax = 0x1112;
  70         /* ireg.bl = 0; */
  71         intcall(0x10, &ireg, NULL);
  72
  73         /* Use alternate print screen */
  74         ireg.ax = 0x1200;
  75         ireg.bl = 0x20;
  76         intcall(0x10, &ireg, NULL);
  77
  78         /* Turn off cursor emulation */
  79         ireg.ax = 0x1201;
  80         ireg.bl = 0x34;
  81         intcall(0x10, &ireg, NULL);
  82
  83         /* Cursor is scan lines 6-7 */
  84         ireg.ax = 0x0100;
  85         ireg.cx = 0x0607;
  86         intcall(0x10, &ireg, NULL);
  87 }
  88
  89 static void vga_set_14font(void)
  90 {
  91         /* Set 9x14 font - 80x28 on VGA */
  92         struct biosregs ireg;
  93
  94         initregs(&ireg);
  95
  96         /* Set 9x14 font */
  97         ireg.ax = 0x1111;
  98         /* ireg.bl = 0; */
  99         intcall(0x10, &ireg, NULL);
 100
 101         /* Turn off cursor emulation */
 102         ireg.ax = 0x1201;
 103         ireg.bl = 0x34;
 104         intcall(0x10, &ireg, NULL);
 105
 106         /* Cursor is scan lines 11-12 */
 107         ireg.ax = 0x0100;
 108         ireg.cx = 0x0b0c;
 109         intcall(0x10, &ireg, NULL);
 110 }
 111
 112 static void vga_set_80x43(void)
 113 {
 114         /* Set 80x43 mode on VGA (not EGA) */
 115         struct biosregs ireg;
 116
 117         initregs(&ireg);
 118
 119         /* Set 350 scans */
 120         ireg.ax = 0x1201;
 121         ireg.bl = 0x30;
 122         intcall(0x10, &ireg, NULL);
 123
 124         /* Reset video mode */
 125         ireg.ax = 0x0003;
 126         intcall(0x10, &ireg, NULL);
 127
 128         vga_set_8font();
 129 }
 130
 131 /* I/O address of the VGA CRTC */
 132 u16 vga_crtc(void)
 133 {
 134         return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
 135 }
 136
 137 static void vga_set_480_scanlines(void)
 138 {
 139         u16 crtc;               /* CRTC base address */
 140         u8  csel;               /* CRTC miscellaneous output register */
 141
 142         crtc = vga_crtc();
 143
 144         out_idx(0x0c, crtc, 0x11); /* Vertical sync end, unlock CR0-7 */
 145         out_idx(0x0b, crtc, 0x06); /* Vertical total */
 146         out_idx(0x3e, crtc, 0x07); /* Vertical overflow */
 147         out_idx(0xea, crtc, 0x10); /* Vertical sync start */
 148         out_idx(0xdf, crtc, 0x12); /* Vertical display end */
 149         out_idx(0xe7, crtc, 0x15); /* Vertical blank start */
 150         out_idx(0x04, crtc, 0x16); /* Vertical blank end */
 151         csel = inb(0x3cc);
 152         csel &= 0x0d;
 153         csel |= 0xe2;
 154         outb(csel, 0x3c2);
 155 }
 156
 157 static void vga_set_vertical_end(int lines)
 158 {
 159         u16 crtc;               /* CRTC base address */
 160         u8  ovfw;               /* CRTC overflow register */
 161         int end = lines-1;
 162
 163         crtc = vga_crtc();
 164
 165         ovfw = 0x3c | ((end >> (8-1)) & 0x02) | ((end >> (9-6)) & 0x40);
 166
 167         out_idx(ovfw, crtc, 0x07); /* Vertical overflow */
 168         out_idx(end,  crtc, 0x12); /* Vertical display end */
 169 }
 170
 171 static void vga_set_80x30(void)
 172 {
 173         vga_set_480_scanlines();
 174         vga_set_vertical_end(30*16);
 175 }
 176
 177 static void vga_set_80x34(void)
 178 {
 179         vga_set_480_scanlines();
 180         vga_set_14font();
 181         vga_set_vertical_end(34*14);
 182 }
 183
 184 static void vga_set_80x60(void)
 185 {
 186         vga_set_480_scanlines();
 187         vga_set_8font();
 188         vga_set_vertical_end(60*8);
 189 }
 190
 191 static int vga_set_mode(struct mode_info *mode)
 192 {
 193         /* Set the basic mode */
 194         vga_set_basic_mode();
 195
 196         /* Override a possibly broken BIOS */
 197         force_x = mode->x;
 198         force_y = mode->y;
 199
 200         switch (mode->mode) {
 201         case VIDEO_80x25:
 202                 break;
 203         case VIDEO_8POINT:
 204                 vga_set_8font();
 205                 break;
 206         case VIDEO_80x43:
 207                 vga_set_80x43();
 208                 break;
 209         case VIDEO_80x28:
 210                 vga_set_14font();
 211                 break;
 212         case VIDEO_80x30:
 213                 vga_set_80x30();
 214                 break;
 215         case VIDEO_80x34:
 216                 vga_set_80x34();
 217                 break;
 218         case VIDEO_80x60:
 219                 vga_set_80x60();
 220                 break;
 221         }
 222
 223         return 0;
 224 }
 225
 226 /*
 227  * Note: this probe includes basic information required by all
 228  * systems.  It should be executed first, by making sure
 229  * video-vga.c is listed first in the Makefile.
 230  */
 231 static int vga_probe(void)
 232 {
 233         static const char *card_name[] = {
 234                 "CGA/MDA/HGC", "EGA", "VGA"
 235         };
 236         static struct mode_info *mode_lists[] = {
 237                 cga_modes,
 238                 ega_modes,
 239                 vga_modes,
 240         };
 241         static int mode_count[] = {
 242                 ARRAY_SIZE(cga_modes),
 243                 ARRAY_SIZE(ega_modes),
 244                 ARRAY_SIZE(vga_modes),
 245         };
 246
 247         struct biosregs ireg, oreg;
 248
 249         initregs(&ireg);
 250
 251         ireg.ax = 0x1200;
 252         ireg.bl = 0x10;         /* Check EGA/VGA */
 253         intcall(0x10, &ireg, &oreg);
 254
 255 #ifndef _WAKEUP
 256         boot_params.screen_info.orig_video_ega_bx = oreg.bx;
 257 #endif
 258
 259         /* If we have MDA/CGA/HGC then BL will be unchanged at 0x10 */
 260         if (oreg.bl != 0x10) {
 261                 /* EGA/VGA */
 262                 ireg.ax = 0x1a00;
 263                 intcall(0x10, &ireg, &oreg);
 264
 265                 if (oreg.al == 0x1a) {
 266                         adapter = ADAPTER_VGA;
 267 #ifndef _WAKEUP
 268                         boot_params.screen_info.orig_video_isVGA = 1;
 269 #endif
 270                 } else {
 271                         adapter = ADAPTER_EGA;
 272                 }
 273         } else {
 274                 adapter = ADAPTER_CGA;
 275         }
 276
 277         video_vga.modes = mode_lists[adapter];
 278         video_vga.card_name = card_name[adapter];
 279         return mode_count[adapter];
 280 }
 281
 282 static __videocard video_vga = {
 283         .card_name      = "VGA",
 284         .probe          = vga_probe,
 285         .set_mode       = vga_set_mode,
 286 };