xref: /openbmc/linux/arch/x86/boot/video.c (revision 97873a3d)
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 
20 static u16 video_segment;
21 
store_cursor_position(void)22 static void store_cursor_position(void)
23 {
24 	struct biosregs ireg, oreg;
25 
26 	initregs(&ireg);
27 	ireg.ah = 0x03;
28 	intcall(0x10, &ireg, &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 
store_video_mode(void)40 static 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(&ireg);
47 	ireg.ah = 0x0f;
48 	intcall(0x10, &ireg, &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  */
store_mode_params(void)61 static 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(0x485); /* Font size, BIOS area */
84 	boot_params.screen_info.orig_video_points = font_size;
85 
86 	x = rdfs16(0x44a);
87 	y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(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 
get_entry(void)98 static 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 
display_menu(void)137 static 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(resbuf, "%dx%d", mi->y, mi->depth);
174 			else
175 				sprintf(resbuf, "%d", mi->y);
176 
177 			printf("%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 
mode_menu(void)200 static 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(1);
229 	}
230 }
231 
232 /* Save screen content to the heap */
233 static struct saved_screen {
234 	int x, y;
235 	int curx, cury;
236 	u16 *data;
237 } saved;
238 
save_screen(void)239 static 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(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(saved.data, 0, saved.x*saved.y*sizeof(u16));
254 }
255 
restore_screen(void)256 static 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, 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(&ireg);
309 	ireg.ah = 0x02;		/* Set cursor position */
310 	ireg.dh = saved.cury;
311 	ireg.dl = saved.curx;
312 	intcall(0x10, &ireg, NULL);
313 
314 	store_cursor_position();
315 }
316 
set_video(void)317 void 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(0);
326 
327 	for (;;) {
328 		if (mode == ASK_VGA)
329 			mode = mode_menu();
330 
331 		if (!set_mode(mode))
332 			break;
333 
334 		printf("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