x86/boot/video.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* -*- linux-c -*- ------------------------------------------------------- *
0003  *
0004  *   Copyright (C) 1991, 1992 Linus Torvalds
0005  *   Copyright 2007 rPath, Inc. - All Rights Reserved
0006  *   Copyright 2009 Intel Corporation; author H. Peter Anvin
0007  *
0008  * ----------------------------------------------------------------------- */
0009
0010 /*
0011  * Select video mode
0012  */
0013
0014 #include <uapi/asm/boot.h>
0015
0016 #include "boot.h"
0017 #include "video.h"
0018 #include "vesa.h"
0019
0020 static u16 video_segment;
0021
0022 static void store_cursor_position(void)
0023 {
0024     struct biosregs ireg, oreg;
0025
0026     initregs(&ireg);
0027     ireg.ah = 0x03;
0028     intcall(0x10, &ireg, &oreg);
0029
0030     boot_params.screen_info.orig_x = oreg.dl;
0031     boot_params.screen_info.orig_y = oreg.dh;
0032
0033     if (oreg.ch & 0x20)
0034         boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;
0035
0036     if ((oreg.ch & 0x1f) > (oreg.cl & 0x1f))
0037         boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;
0038 }
0039
0040 static void store_video_mode(void)
0041 {
0042     struct biosregs ireg, oreg;
0043
0044     /* N.B.: the saving of the video page here is a bit silly,
0045        since we pretty much assume page 0 everywhere. */
0046     initregs(&ireg);
0047     ireg.ah = 0x0f;
0048     intcall(0x10, &ireg, &oreg);
0049
0050     /* Not all BIOSes are clean with respect to the top bit */
0051     boot_params.screen_info.orig_video_mode = oreg.al & 0x7f;
0052     boot_params.screen_info.orig_video_page = oreg.bh;
0053 }
0054
0055 /*
0056  * Store the video mode parameters for later usage by the kernel.
0057  * This is done by asking the BIOS except for the rows/columns
0058  * parameters in the default 80x25 mode -- these are set directly,
0059  * because some very obscure BIOSes supply insane values.
0060  */
0061 static void store_mode_params(void)
0062 {
0063     u16 font_size;
0064     int x, y;
0065
0066     /* For graphics mode, it is up to the mode-setting driver
0067        (currently only video-vesa.c) to store the parameters */
0068     if (graphic_mode)
0069         return;
0070
0071     store_cursor_position();
0072     store_video_mode();
0073
0074     if (boot_params.screen_info.orig_video_mode == 0x07) {
0075         /* MDA, HGC, or VGA in monochrome mode */
0076         video_segment = 0xb000;
0077     } else {
0078         /* CGA, EGA, VGA and so forth */
0079         video_segment = 0xb800;
0080     }
0081
0082     set_fs(0);
0083     font_size = rdfs16(0x485); /* Font size, BIOS area */
0084     boot_params.screen_info.orig_video_points = font_size;
0085
0086     x = rdfs16(0x44a);
0087     y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(0x484)+1;
0088
0089     if (force_x)
0090         x = force_x;
0091     if (force_y)
0092         y = force_y;
0093
0094     boot_params.screen_info.orig_video_cols  = x;
0095     boot_params.screen_info.orig_video_lines = y;
0096 }
0097
0098 static unsigned int get_entry(void)
0099 {
0100     char entry_buf[4];
0101     int i, len = 0;
0102     int key;
0103     unsigned int v;
0104
0105     do {
0106         key = getchar();
0107
0108         if (key == '\b') {
0109             if (len > 0) {
0110                 puts("\b \b");
0111                 len--;
0112             }
0113         } else if ((key >= '0' && key <= '9') ||
0114                (key >= 'A' && key <= 'Z') ||
0115                (key >= 'a' && key <= 'z')) {
0116             if (len < sizeof(entry_buf)) {
0117                 entry_buf[len++] = key;
0118                 putchar(key);
0119             }
0120         }
0121     } while (key != '\r');
0122     putchar('\n');
0123
0124     if (len == 0)
0125         return VIDEO_CURRENT_MODE; /* Default */
0126
0127     v = 0;
0128     for (i = 0; i < len; i++) {
0129         v <<= 4;
0130         key = entry_buf[i] | 0x20;
0131         v += (key > '9') ? key-'a'+10 : key-'0';
0132     }
0133
0134     return v;
0135 }
0136
0137 static void display_menu(void)
0138 {
0139     struct card_info *card;
0140     struct mode_info *mi;
0141     char ch;
0142     int i;
0143     int nmodes;
0144     int modes_per_line;
0145     int col;
0146
0147     nmodes = 0;
0148     for (card = video_cards; card < video_cards_end; card++)
0149         nmodes += card->nmodes;
0150
0151     modes_per_line = 1;
0152     if (nmodes >= 20)
0153         modes_per_line = 3;
0154
0155     for (col = 0; col < modes_per_line; col++)
0156         puts("Mode: Resolution:  Type: ");
0157     putchar('\n');
0158
0159     col = 0;
0160     ch = '0';
0161     for (card = video_cards; card < video_cards_end; card++) {
0162         mi = card->modes;
0163         for (i = 0; i < card->nmodes; i++, mi++) {
0164             char resbuf[32];
0165             int visible = mi->x && mi->y;
0166             u16 mode_id = mi->mode ? mi->mode :
0167                 (mi->y << 8)+mi->x;
0168
0169             if (!visible)
0170                 continue; /* Hidden mode */
0171
0172             if (mi->depth)
0173                 sprintf(resbuf, "%dx%d", mi->y, mi->depth);
0174             else
0175                 sprintf(resbuf, "%d", mi->y);
0176
0177             printf("%c %03X %4dx%-7s %-6s",
0178                    ch, mode_id, mi->x, resbuf, card->card_name);
0179             col++;
0180             if (col >= modes_per_line) {
0181                 putchar('\n');
0182                 col = 0;
0183             }
0184
0185             if (ch == '9')
0186                 ch = 'a';
0187             else if (ch == 'z' || ch == ' ')
0188                 ch = ' '; /* Out of keys... */
0189             else
0190                 ch++;
0191         }
0192     }
0193     if (col)
0194         putchar('\n');
0195 }
0196
0197 #define H(x)    ((x)-'a'+10)
0198 #define SCAN    ((H('s')<<12)+(H('c')<<8)+(H('a')<<4)+H('n'))
0199
0200 static unsigned int mode_menu(void)
0201 {
0202     int key;
0203     unsigned int sel;
0204
0205     puts("Press <ENTER> to see video modes available, "
0206          "<SPACE> to continue, or wait 30 sec\n");
0207
0208     kbd_flush();
0209     while (1) {
0210         key = getchar_timeout();
0211         if (key == ' ' || key == 0)
0212             return VIDEO_CURRENT_MODE; /* Default */
0213         if (key == '\r')
0214             break;
0215         putchar('\a');  /* Beep! */
0216     }
0217
0218
0219     for (;;) {
0220         display_menu();
0221
0222         puts("Enter a video mode or \"scan\" to scan for "
0223              "additional modes: ");
0224         sel = get_entry();
0225         if (sel != SCAN)
0226             return sel;
0227
0228         probe_cards(1);
0229     }
0230 }
0231
0232 /* Save screen content to the heap */
0233 static struct saved_screen {
0234     int x, y;
0235     int curx, cury;
0236     u16 *data;
0237 } saved;
0238
0239 static void save_screen(void)
0240 {
0241     /* Should be called after store_mode_params() */
0242     saved.x = boot_params.screen_info.orig_video_cols;
0243     saved.y = boot_params.screen_info.orig_video_lines;
0244     saved.curx = boot_params.screen_info.orig_x;
0245     saved.cury = boot_params.screen_info.orig_y;
0246
0247     if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
0248         return;     /* Not enough heap to save the screen */
0249
0250     saved.data = GET_HEAP(u16, saved.x*saved.y);
0251
0252     set_fs(video_segment);
0253     copy_from_fs(saved.data, 0, saved.x*saved.y*sizeof(u16));
0254 }
0255
0256 static void restore_screen(void)
0257 {
0258     /* Should be called after store_mode_params() */
0259     int xs = boot_params.screen_info.orig_video_cols;
0260     int ys = boot_params.screen_info.orig_video_lines;
0261     int y;
0262     addr_t dst = 0;
0263     u16 *src = saved.data;
0264     struct biosregs ireg;
0265
0266     if (graphic_mode)
0267         return;     /* Can't restore onto a graphic mode */
0268
0269     if (!src)
0270         return;     /* No saved screen contents */
0271
0272     /* Restore screen contents */
0273
0274     set_fs(video_segment);
0275     for (y = 0; y < ys; y++) {
0276         int npad;
0277
0278         if (y < saved.y) {
0279             int copy = (xs < saved.x) ? xs : saved.x;
0280             copy_to_fs(dst, src, copy*sizeof(u16));
0281             dst += copy*sizeof(u16);
0282             src += saved.x;
0283             npad = (xs < saved.x) ? 0 : xs-saved.x;
0284         } else {
0285             npad = xs;
0286         }
0287
0288         /* Writes "npad" blank characters to
0289            video_segment:dst and advances dst */
0290         asm volatile("pushw %%es ; "
0291                  "movw %2,%%es ; "
0292                  "shrw %%cx ; "
0293                  "jnc 1f ; "
0294                  "stosw \n\t"
0295                  "1: rep;stosl ; "
0296                  "popw %%es"
0297                  : "+D" (dst), "+c" (npad)
0298                  : "bdS" (video_segment),
0299                    "a" (0x07200720));
0300     }
0301
0302     /* Restore cursor position */
0303     if (saved.curx >= xs)
0304         saved.curx = xs-1;
0305     if (saved.cury >= ys)
0306         saved.cury = ys-1;
0307
0308     initregs(&ireg);
0309     ireg.ah = 0x02;     /* Set cursor position */
0310     ireg.dh = saved.cury;
0311     ireg.dl = saved.curx;
0312     intcall(0x10, &ireg, NULL);
0313
0314     store_cursor_position();
0315 }
0316
0317 void set_video(void)
0318 {
0319     u16 mode = boot_params.hdr.vid_mode;
0320
0321     RESET_HEAP();
0322
0323     store_mode_params();
0324     save_screen();
0325     probe_cards(0);
0326
0327     for (;;) {
0328         if (mode == ASK_VGA)
0329             mode = mode_menu();
0330
0331         if (!set_mode(mode))
0332             break;
0333
0334         printf("Undefined video mode number: %x\n", mode);
0335         mode = ASK_VGA;
0336     }
0337     boot_params.hdr.vid_mode = mode;
0338     vesa_store_edid();
0339     store_mode_params();
0340
0341     if (do_restore)
0342         restore_screen();
0343 }