LXR linux/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
  17static 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
  27static struct mode_info ega_modes[] = {
  28        { VIDEO_80x25,  80, 25, 0 },
  29        { VIDEO_8POINT, 80, 43, 0 },
  30};
  31
  32static struct mode_info cga_modes[] = {
  33        { VIDEO_80x25,  80, 25, 0 },
  34};
  35
  36static __videocard video_vga;
  37
  38/* Set basic 80x25 mode */
  39static 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
  61static 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
  89static 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
 112static 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 */
 132u16 vga_crtc(void)
 133{
 134        return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
 135}
 136
 137static 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
 157static 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
 171static void vga_set_80x30(void)
 172{
 173        vga_set_480_scanlines();
 174        vga_set_vertical_end(30*16);
 175}
 176
 177static void vga_set_80x34(void)
 178{
 179        vga_set_480_scanlines();
 180        vga_set_14font();
 181        vga_set_vertical_end(34*14);
 182}
 183
 184static void vga_set_80x60(void)
 185{
 186        vga_set_480_scanlines();
 187        vga_set_8font();
 188        vga_set_vertical_end(60*8);
 189}
 190
 191static 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 */
 231static 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
 282static __videocard video_vga = {
 283        .card_name      = "VGA",
 284        .probe          = vga_probe,
 285        .set_mode       = vga_set_mode,
 286};
 287