1/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 * Copyright 2009 Intel Corporation; author H. Peter Anvin
6 *
7 * This file is part of the Linux kernel, and is made available under
8 * the terms of the GNU General Public License version 2.
9 *
10 * ----------------------------------------------------------------------- */
11
12/*
13 * Standard video BIOS modes
14 *
15 * We have two options for this; silent and scanned.
16 */
17
18#include "boot.h"
19#include "video.h"
20
21static __videocard video_bios;
22
23/* Set a conventional BIOS mode */
24static int set_bios_mode(u8 mode);
25
26static int bios_set_mode(struct mode_info *mi)
27{
28 return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS);
29}
30
31static int set_bios_mode(u8 mode)
32{
33 struct biosregs ireg, oreg;
34 u8 new_mode;
35
36 initregs(&ireg);
37 ireg.al = mode; /* AH=0x00 Set Video Mode */
38 intcall(0x10, &ireg, NULL);
39
40 ireg.ah = 0x0f; /* Get Current Video Mode */
41 intcall(0x10, &ireg, &oreg);
42
43 do_restore = 1; /* Assume video contents were lost */
44
45 /* Not all BIOSes are clean with the top bit */
46 new_mode = oreg.al & 0x7f;
47
48 if (new_mode == mode)
49 return 0; /* Mode change OK */
50
51#ifndef _WAKEUP
52 if (new_mode != boot_params.screen_info.orig_video_mode) {
53 /* Mode setting failed, but we didn't end up where we
54 started. That's bad. Try to revert to the original
55 video mode. */
56 ireg.ax = boot_params.screen_info.orig_video_mode;
57 intcall(0x10, &ireg, NULL);
58 }
59#endif
60 return -1;
61}
62
63static int bios_probe(void)
64{
65 u8 mode;
66#ifdef _WAKEUP
67 u8 saved_mode = 0x03;
68#else
69 u8 saved_mode = boot_params.screen_info.orig_video_mode;
70#endif
71 u16 crtc;
72 struct mode_info *mi;
73 int nmodes = 0;
74
75 if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA)
76 return 0;
77
78 set_fs(0);
79 crtc = vga_crtc();
80
81 video_bios.modes = GET_HEAP(struct mode_info, 0);
82
83 for (mode = 0x14; mode <= 0x7f; mode++) {
84 if (!heap_free(sizeof(struct mode_info)))
85 break;
86
87 if (mode_defined(VIDEO_FIRST_BIOS+mode))
88 continue;
89
90 if (set_bios_mode(mode))
91 continue;
92
93 /* Try to verify that it's a text mode. */
94
95 /* Attribute Controller: make graphics controller disabled */
96 if (in_idx(0x3c0, 0x10) & 0x01)
97 continue;
98
99 /* Graphics Controller: verify Alpha addressing enabled */
100 if (in_idx(0x3ce, 0x06) & 0x01)
101 continue;
102
103 /* CRTC cursor location low should be zero(?) */
104 if (in_idx(crtc, 0x0f))
105 continue;
106
107 mi = GET_HEAP(struct mode_info, 1);
108 mi->mode = VIDEO_FIRST_BIOS+mode;
109 mi->depth = 0; /* text */
110 mi->x = rdfs16(0x44a);
111 mi->y = rdfs8(0x484)+1;
112 nmodes++;
113 }
114
115 set_bios_mode(saved_mode);
116
117 return nmodes;
118}
119
120static __videocard video_bios =
121{
122 .card_name = "BIOS",
123 .probe = bios_probe,
124 .set_mode = bios_set_mode,
125 .unsafe = 1,
126 .xmode_first = VIDEO_FIRST_BIOS,
127 .xmode_n = 0x80,
128};
129