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 * Select video mode
12 */
13
14#include <uapi/asm/boot.h>
15
16#include "boot.h"
17#include "video.h"
18#include "vesa.h"
19
20static u16 video_segment;
21
22static void store_cursor_position(void)
23{
24 struct biosregs ireg, oreg;
25
26 initregs(regs: &ireg);
27 ireg.ah = 0x03;
28 intcall(int_no: 0x10, ireg: &ireg, oreg: &oreg);
29
30 boot_params.screen_info.orig_x = oreg.dl;
31 boot_params.screen_info.orig_y = oreg.dh;
32
33 if (oreg.ch & 0x20)
34 boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;
35
36 if ((oreg.ch & 0x1f) > (oreg.cl & 0x1f))
37 boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;
38}
39
40static void store_video_mode(void)
41{
42 struct biosregs ireg, oreg;
43
44 /* N.B.: the saving of the video page here is a bit silly,
45 since we pretty much assume page 0 everywhere. */
46 initregs(regs: &ireg);
47 ireg.ah = 0x0f;
48 intcall(int_no: 0x10, ireg: &ireg, oreg: &oreg);
49
50 /* Not all BIOSes are clean with respect to the top bit */
51 boot_params.screen_info.orig_video_mode = oreg.al & 0x7f;
52 boot_params.screen_info.orig_video_page = oreg.bh;
53}
54
55/*
56 * Store the video mode parameters for later usage by the kernel.
57 * This is done by asking the BIOS except for the rows/columns
58 * parameters in the default 80x25 mode -- these are set directly,
59 * because some very obscure BIOSes supply insane values.
60 */
61static void store_mode_params(void)
62{
63 u16 font_size;
64 int x, y;
65
66 /* For graphics mode, it is up to the mode-setting driver
67 (currently only video-vesa.c) to store the parameters */
68 if (graphic_mode)
69 return;
70
71 store_cursor_position();
72 store_video_mode();
73
74 if (boot_params.screen_info.orig_video_mode == 0x07) {
75 /* MDA, HGC, or VGA in monochrome mode */
76 video_segment = 0xb000;
77 } else {
78 /* CGA, EGA, VGA and so forth */
79 video_segment = 0xb800;
80 }
81
82 set_fs(0);
83 font_size = rdfs16(addr: 0x485); /* Font size, BIOS area */
84 boot_params.screen_info.orig_video_points = font_size;
85
86 x = rdfs16(addr: 0x44a);
87 y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(addr: 0x484)+1;
88
89 if (force_x)
90 x = force_x;
91 if (force_y)
92 y = force_y;
93
94 boot_params.screen_info.orig_video_cols = x;
95 boot_params.screen_info.orig_video_lines = y;
96}
97
98static unsigned int get_entry(void)
99{
100 char entry_buf[4];
101 int i, len = 0;
102 int key;
103 unsigned int v;
104
105 do {
106 key = getchar();
107
108 if (key == '\b') {
109 if (len > 0) {
110 puts("\b \b");
111 len--;
112 }
113 } else if ((key >= '0' && key <= '9') ||
114 (key >= 'A' && key <= 'Z') ||
115 (key >= 'a' && key <= 'z')) {
116 if (len < sizeof(entry_buf)) {
117 entry_buf[len++] = key;
118 putchar(key);
119 }
120 }
121 } while (key != '\r');
122 putchar('\n');
123
124 if (len == 0)
125 return VIDEO_CURRENT_MODE; /* Default */
126
127 v = 0;
128 for (i = 0; i < len; i++) {
129 v <<= 4;
130 key = entry_buf[i] | 0x20;
131 v += (key > '9') ? key-'a'+10 : key-'0';
132 }
133
134 return v;
135}
136
137static void display_menu(void)
138{
139 struct card_info *card;
140 struct mode_info *mi;
141 char ch;
142 int i;
143 int nmodes;
144 int modes_per_line;
145 int col;
146
147 nmodes = 0;
148 for (card = video_cards; card < video_cards_end; card++)
149 nmodes += card->nmodes;
150
151 modes_per_line = 1;
152 if (nmodes >= 20)
153 modes_per_line = 3;
154
155 for (col = 0; col < modes_per_line; col++)
156 puts("Mode: Resolution: Type: ");
157 putchar('\n');
158
159 col = 0;
160 ch = '0';
161 for (card = video_cards; card < video_cards_end; card++) {
162 mi = card->modes;
163 for (i = 0; i < card->nmodes; i++, mi++) {
164 char resbuf[32];
165 int visible = mi->x && mi->y;
166 u16 mode_id = mi->mode ? mi->mode :
167 (mi->y << 8)+mi->x;
168
169 if (!visible)
170 continue; /* Hidden mode */
171
172 if (mi->depth)
173 sprintf(buf: resbuf, fmt: "%dx%d", mi->y, mi->depth);
174 else
175 sprintf(buf: resbuf, fmt: "%d", mi->y);
176
177 printf(fmt: "%c %03X %4dx%-7s %-6s",
178 ch, mode_id, mi->x, resbuf, card->card_name);
179 col++;
180 if (col >= modes_per_line) {
181 putchar('\n');
182 col = 0;
183 }
184
185 if (ch == '9')
186 ch = 'a';
187 else if (ch == 'z' || ch == ' ')
188 ch = ' '; /* Out of keys... */
189 else
190 ch++;
191 }
192 }
193 if (col)
194 putchar('\n');
195}
196
197#define H(x) ((x)-'a'+10)
198#define SCAN ((H('s')<<12)+(H('c')<<8)+(H('a')<<4)+H('n'))
199
200static unsigned int mode_menu(void)
201{
202 int key;
203 unsigned int sel;
204
205 puts("Press <ENTER> to see video modes available, "
206 "<SPACE> to continue, or wait 30 sec\n");
207
208 kbd_flush();
209 while (1) {
210 key = getchar_timeout();
211 if (key == ' ' || key == 0)
212 return VIDEO_CURRENT_MODE; /* Default */
213 if (key == '\r')
214 break;
215 putchar('\a'); /* Beep! */
216 }
217
218
219 for (;;) {
220 display_menu();
221
222 puts("Enter a video mode or \"scan\" to scan for "
223 "additional modes: ");
224 sel = get_entry();
225 if (sel != SCAN)
226 return sel;
227
228 probe_cards(unsafe: 1);
229 }
230}
231
232/* Save screen content to the heap */
233static struct saved_screen {
234 int x, y;
235 int curx, cury;
236 u16 *data;
237} saved;
238
239static void save_screen(void)
240{
241 /* Should be called after store_mode_params() */
242 saved.x = boot_params.screen_info.orig_video_cols;
243 saved.y = boot_params.screen_info.orig_video_lines;
244 saved.curx = boot_params.screen_info.orig_x;
245 saved.cury = boot_params.screen_info.orig_y;
246
247 if (!heap_free(n: saved.x*saved.y*sizeof(u16)+512))
248 return; /* Not enough heap to save the screen */
249
250 saved.data = GET_HEAP(u16, saved.x*saved.y);
251
252 set_fs(video_segment);
253 copy_from_fs(dst: saved.data, src: 0, len: saved.x*saved.y*sizeof(u16));
254}
255
256static void restore_screen(void)
257{
258 /* Should be called after store_mode_params() */
259 int xs = boot_params.screen_info.orig_video_cols;
260 int ys = boot_params.screen_info.orig_video_lines;
261 int y;
262 addr_t dst = 0;
263 u16 *src = saved.data;
264 struct biosregs ireg;
265
266 if (graphic_mode)
267 return; /* Can't restore onto a graphic mode */
268
269 if (!src)
270 return; /* No saved screen contents */
271
272 /* Restore screen contents */
273
274 set_fs(video_segment);
275 for (y = 0; y < ys; y++) {
276 int npad;
277
278 if (y < saved.y) {
279 int copy = (xs < saved.x) ? xs : saved.x;
280 copy_to_fs(dst, src, len: copy*sizeof(u16));
281 dst += copy*sizeof(u16);
282 src += saved.x;
283 npad = (xs < saved.x) ? 0 : xs-saved.x;
284 } else {
285 npad = xs;
286 }
287
288 /* Writes "npad" blank characters to
289 video_segment:dst and advances dst */
290 asm volatile("pushw %%es ; "
291 "movw %2,%%es ; "
292 "shrw %%cx ; "
293 "jnc 1f ; "
294 "stosw \n\t"
295 "1: rep;stosl ; "
296 "popw %%es"
297 : "+D" (dst), "+c" (npad)
298 : "bdS" (video_segment),
299 "a" (0x07200720));
300 }
301
302 /* Restore cursor position */
303 if (saved.curx >= xs)
304 saved.curx = xs-1;
305 if (saved.cury >= ys)
306 saved.cury = ys-1;
307
308 initregs(regs: &ireg);
309 ireg.ah = 0x02; /* Set cursor position */
310 ireg.dh = saved.cury;
311 ireg.dl = saved.curx;
312 intcall(int_no: 0x10, ireg: &ireg, NULL);
313
314 store_cursor_position();
315}
316
317void set_video(void)
318{
319 u16 mode = boot_params.hdr.vid_mode;
320
321 RESET_HEAP();
322
323 store_mode_params();
324 save_screen();
325 probe_cards(unsafe: 0);
326
327 for (;;) {
328 if (mode == ASK_VGA)
329 mode = mode_menu();
330
331 if (!set_mode(mode))
332 break;
333
334 printf(fmt: "Undefined video mode number: %x\n", mode);
335 mode = ASK_VGA;
336 }
337 boot_params.hdr.vid_mode = mode;
338 vesa_store_edid();
339 store_mode_params();
340
341 if (do_restore)
342 restore_screen();
343}
344

source code of linux/arch/x86/boot/video.c