1 /* -*- linux-c -*- ------------------------------------------------------- *
2  *
3  *   Copyright (C) 1991, 1992 Linus Torvalds
4  *   Copyright 2007-2008 rPath, Inc. - All Rights Reserved
5  *
6  *   This file is part of the Linux kernel, and is made available under
7  *   the terms of the GNU General Public License version 2.
8  *
9  * ----------------------------------------------------------------------- */
10 
11 /*
12  * arch/i386/boot/video-mode.c
13  *
14  * Set the video mode.  This is separated out into a different
15  * file in order to be shared with the ACPI wakeup code.
16  */
17 
18 #include "boot.h"
19 #include "video.h"
20 #include "vesa.h"
21 
22 /*
23  * Common variables
24  */
25 int adapter;			/* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
26 u16 video_segment;
27 int force_x, force_y;	/* Don't query the BIOS for cols/rows */
28 
29 int do_restore;		/* Screen contents changed during mode flip */
30 int graphic_mode;	/* Graphic mode with linear frame buffer */
31 
32 /* Probe the video drivers and have them generate their mode lists. */
probe_cards(int unsafe)33 void probe_cards(int unsafe)
34 {
35 	struct card_info *card;
36 	static u8 probed[2];
37 
38 	if (probed[unsafe])
39 		return;
40 
41 	probed[unsafe] = 1;
42 
43 	for (card = video_cards; card < video_cards_end; card++) {
44 		if (card->unsafe == unsafe) {
45 			if (card->probe)
46 				card->nmodes = card->probe();
47 			else
48 				card->nmodes = 0;
49 		}
50 	}
51 }
52 
53 /* Test if a mode is defined */
mode_defined(u16 mode)54 int mode_defined(u16 mode)
55 {
56 	struct card_info *card;
57 	struct mode_info *mi;
58 	int i;
59 
60 	for (card = video_cards; card < video_cards_end; card++) {
61 		mi = card->modes;
62 		for (i = 0; i < card->nmodes; i++, mi++) {
63 			if (mi->mode == mode)
64 				return 1;
65 		}
66 	}
67 
68 	return 0;
69 }
70 
71 /* Set mode (without recalc) */
raw_set_mode(u16 mode,u16 * real_mode)72 static int raw_set_mode(u16 mode, u16 *real_mode)
73 {
74 	int nmode, i;
75 	struct card_info *card;
76 	struct mode_info *mi;
77 
78 	/* Drop the recalc bit if set */
79 	mode &= ~VIDEO_RECALC;
80 
81 	/* Scan for mode based on fixed ID, position, or resolution */
82 	nmode = 0;
83 	for (card = video_cards; card < video_cards_end; card++) {
84 		mi = card->modes;
85 		for (i = 0; i < card->nmodes; i++, mi++) {
86 			int visible = mi->x || mi->y;
87 
88 			if ((mode == nmode && visible) ||
89 			    mode == mi->mode ||
90 			    mode == (mi->y << 8)+mi->x) {
91 				*real_mode = mi->mode;
92 				return card->set_mode(mi);
93 			}
94 
95 			if (visible)
96 				nmode++;
97 		}
98 	}
99 
100 	/* Nothing found?  Is it an "exceptional" (unprobed) mode? */
101 	for (card = video_cards; card < video_cards_end; card++) {
102 		if (mode >= card->xmode_first &&
103 		    mode < card->xmode_first+card->xmode_n) {
104 			struct mode_info mix;
105 			*real_mode = mix.mode = mode;
106 			mix.x = mix.y = 0;
107 			return card->set_mode(&mix);
108 		}
109 	}
110 
111 	/* Otherwise, failure... */
112 	return -1;
113 }
114 
115 /*
116  * Recalculate the vertical video cutoff (hack!)
117  */
vga_recalc_vertical(void)118 static void vga_recalc_vertical(void)
119 {
120 	unsigned int font_size, rows;
121 	u16 crtc;
122 	u8 pt, ov;
123 
124 	set_fs(0);
125 	font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
126 	rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
127 
128 	rows *= font_size;	/* Visible scan lines */
129 	rows--;			/* ... minus one */
130 
131 	crtc = vga_crtc();
132 
133 	pt = in_idx(crtc, 0x11);
134 	pt &= ~0x80;		/* Unlock CR0-7 */
135 	out_idx(pt, crtc, 0x11);
136 
137 	out_idx((u8)rows, crtc, 0x12); /* Lower height register */
138 
139 	ov = in_idx(crtc, 0x07); /* Overflow register */
140 	ov &= 0xbd;
141 	ov |= (rows >> (8-1)) & 0x02;
142 	ov |= (rows >> (9-6)) & 0x40;
143 	out_idx(ov, crtc, 0x07);
144 }
145 
146 /* Set mode (with recalc if specified) */
set_mode(u16 mode)147 int set_mode(u16 mode)
148 {
149 	int rv;
150 	u16 real_mode;
151 
152 	/* Very special mode numbers... */
153 	if (mode == VIDEO_CURRENT_MODE)
154 		return 0;	/* Nothing to do... */
155 	else if (mode == NORMAL_VGA)
156 		mode = VIDEO_80x25;
157 	else if (mode == EXTENDED_VGA)
158 		mode = VIDEO_8POINT;
159 
160 	rv = raw_set_mode(mode, &real_mode);
161 	if (rv)
162 		return rv;
163 
164 	if (mode & VIDEO_RECALC)
165 		vga_recalc_vertical();
166 
167 	/* Save the canonical mode number for the kernel, not
168 	   an alias, size specification or menu position */
169 #ifndef _WAKEUP
170 	boot_params.hdr.vid_mode = real_mode;
171 #endif
172 	return 0;
173 }
174