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