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 */
25int adapter;		/* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
26int force_x, force_y;	/* Don't query the BIOS for cols/rows */
27int do_restore;		/* Screen contents changed during mode flip */
28int graphic_mode;	/* Graphic mode with linear frame buffer */
29
30/* Probe the video drivers and have them generate their mode lists. */
31void 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 */
52int 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) */
70static 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 */
116static 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) */
145int 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}
172