1 // SPDX-License-Identifier: GPL-2.0-only
2 /* -*- linux-c -*- ------------------------------------------------------- *
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007-2008 rPath, Inc. - All Rights Reserved
6 *
7 * ----------------------------------------------------------------------- */
8
9 /*
10 * arch/i386/boot/video-mode.c
11 *
12 * Set the video mode. This is separated out into a different
13 * file in order to be shared with the ACPI wakeup code.
14 */
15
16 #include "boot.h"
17 #include "video.h"
18 #include "vesa.h"
19
20 #include <uapi/asm/boot.h>
21
22 /*
23 * Common variables
24 */
25 int adapter; /* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
26 int force_x, force_y; /* Don't query the BIOS for cols/rows */
27 int do_restore; /* Screen contents changed during mode flip */
28 int graphic_mode; /* Graphic mode with linear frame buffer */
29
30 /* Probe the video drivers and have them generate their mode lists. */
31 void probe_cards(int unsafe)
32 {
33 struct card_info *card;
34 static u8 probed[2];
35
36 if (probed[unsafe])
37 return;
38
39 probed[unsafe] = 1;
40
41 for (card = video_cards; card < video_cards_end; card++) {
42 if (card->unsafe == unsafe) {
43 if (card->probe)
44 card->nmodes = card->probe();
45 else
46 card->nmodes = 0;
47 }
48 }
49 }
50
51 /* Test if a mode is defined */
52 int mode_defined(u16 mode)
53 {
54 struct card_info *card;
55 struct mode_info *mi;
56 int i;
57
58 for (card = video_cards; card < video_cards_end; card++) {
59 mi = card->modes;
60 for (i = 0; i < card->nmodes; i++, mi++) {
61 if (mi->mode == mode)
62 return 1;
63 }
64 }
65
66 return 0;
67 }
68
69 /* Set mode (without recalc) */
70 static int raw_set_mode(u16 mode, u16 *real_mode)
71 {
72 int nmode, i;
73 struct card_info *card;
74 struct mode_info *mi;
75
76 /* Drop the recalc bit if set */
77 mode &= ~VIDEO_RECALC;
78
79 /* Scan for mode based on fixed ID, position, or resolution */
80 nmode = 0;
81 for (card = video_cards; card < video_cards_end; card++) {
82 mi = card->modes;
83 for (i = 0; i < card->nmodes; i++, mi++) {
84 int visible = mi->x || mi->y;
85
86 if ((mode == nmode && visible) ||
87 mode == mi->mode ||
88 mode == (mi->y << 8)+mi->x) {
89 *real_mode = mi->mode;
90 return card->set_mode(mi);
91 }
92
93 if (visible)
94 nmode++;
95 }
96 }
97
98 /* Nothing found? Is it an "exceptional" (unprobed) mode? */
99 for (card = video_cards; card < video_cards_end; card++) {
100 if (mode >= card->xmode_first &&
101 mode < card->xmode_first+card->xmode_n) {
102 struct mode_info mix;
103 *real_mode = mix.mode = mode;
104 mix.x = mix.y = 0;
105 return card->set_mode(&mix);
106 }
107 }
108
109 /* Otherwise, failure... */
110 return -1;
111 }
112
113 /*
114 * Recalculate the vertical video cutoff (hack!)
115 */
116 static void vga_recalc_vertical(void)
117 {
118 unsigned int font_size, rows;
119 u16 crtc;
120 u8 pt, ov;
121
122 set_fs(0);
123 font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
124 rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
125
126 rows *= font_size; /* Visible scan lines */
127 rows--; /* ... minus one */
128
129 crtc = vga_crtc();
130
131 pt = in_idx(crtc, 0x11);
132 pt &= ~0x80; /* Unlock CR0-7 */
133 out_idx(pt, crtc, 0x11);
134
135 out_idx((u8)rows, crtc, 0x12); /* Lower height register */
136
137 ov = in_idx(crtc, 0x07); /* Overflow register */
138 ov &= 0xbd;
139 ov |= (rows >> (8-1)) & 0x02;
140 ov |= (rows >> (9-6)) & 0x40;
141 out_idx(ov, crtc, 0x07);
142 }
143
144 /* Set mode (with recalc if specified) */
145 int set_mode(u16 mode)
146 {
147 int rv;
148 u16 real_mode;
149
150 /* Very special mode numbers... */
151 if (mode == VIDEO_CURRENT_MODE)
152 return 0; /* Nothing to do... */
153 else if (mode == NORMAL_VGA)
154 mode = VIDEO_80x25;
155 else if (mode == EXTENDED_VGA)
156 mode = VIDEO_8POINT;
157
158 rv = raw_set_mode(mode, &real_mode);
159 if (rv)
160 return rv;
161
162 if (mode & VIDEO_RECALC)
163 vga_recalc_vertical();
164
165 /* Save the canonical mode number for the kernel, not
166 an alias, size specification or menu position */
167 #ifndef _WAKEUP
168 boot_params.hdr.vid_mode = real_mode;
169 #endif
170 return 0;
171 }