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TOMOYO Linux Cross Reference
Linux/arch/x86/boot/video.c

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  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 
 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 
 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  */
 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 
 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 >= '' && 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-'';
132         }
133 
134         return v;
135 }
136 
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 = '';
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 
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 
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 
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 
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 

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