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
17 static 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
27 static struct mode_info ega_modes[] = {
28 { VIDEO_80x25, 80, 25, 0 },
29 { VIDEO_8POINT, 80, 43, 0 },
30 };
31
32 static struct mode_info cga_modes[] = {
33 { VIDEO_80x25, 80, 25, 0 },
34 };
35
36 static __videocard video_vga;
37
38 /* Set basic 80x25 mode */
vga_set_basic_mode(void)39 static 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
vga_set_8font(void)61 static 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
vga_set_14font(void)89 static 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
vga_set_80x43(void)112 static 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 */
vga_crtc(void)132 u16 vga_crtc(void)
133 {
134 return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
135 }
136
vga_set_480_scanlines(void)137 static 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
vga_set_vertical_end(int lines)157 static 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
vga_set_80x30(void)171 static void vga_set_80x30(void)
172 {
173 vga_set_480_scanlines();
174 vga_set_vertical_end(30*16);
175 }
176
vga_set_80x34(void)177 static void vga_set_80x34(void)
178 {
179 vga_set_480_scanlines();
180 vga_set_14font();
181 vga_set_vertical_end(34*14);
182 }
183
vga_set_80x60(void)184 static void vga_set_80x60(void)
185 {
186 vga_set_480_scanlines();
187 vga_set_8font();
188 vga_set_vertical_end(60*8);
189 }
190
vga_set_mode(struct mode_info * mode)191 static 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 */
vga_probe(void)231 static 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
282 static __videocard video_vga = {
283 .card_name = "VGA",
284 .probe = vga_probe,
285 .set_mode = vga_set_mode,
286 };
287