Video mode probing support for the new x86 setup code

Video mode probing for the new x86 setup code.  This code breaks down
different drivers into modules.  This code deliberately drops support
for a lot of the vendor-specific mode probing present in the assembly
version, since a lot of those probes have been found to be stale in
current versions of those chips -- frequently, support for those modes
have been dropped from recent video BIOSes due to space constraints,
but the video BIOS signatures are still the same.

However, additional drivers should be extremely straightforward to plug
in, if desirable.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 456 insertions, 0 deletions

diff --git a/arch/i386/boot/video.c b/arch/i386/boot/video.c
new file mode 100644
index 00000000000..3bb3573cd6a
--- /dev/null
+++ b/arch/i386/boot/video.c
@@ -0,0 +1,456 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright (C) 1991, 1992 Linus Torvalds
+ *   Copyright 2007 rPath, Inc. - All Rights Reserved
+ *
+ *   This file is part of the Linux kernel, and is made available under
+ *   the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * arch/i386/boot/video.c
+ *
+ * Select video mode
+ */
+
+#include "boot.h"
+#include "video.h"
+#include "vesa.h"
+
+/*
+ * Mode list variables
+ */
+static struct card_info cards[];    /* List of cards to probe for */
+
+/*
+ * Common variables
+ */
+int adapter;			/* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
+u16 video_segment;
+int force_x, force_y;	/* Don't query the BIOS for cols/rows */
+
+int do_restore = 0;	/* Screen contents changed during mode flip */
+int graphic_mode;	/* Graphic mode with linear frame buffer */
+
+static void store_cursor_position(void)
+{
+	u16 curpos;
+	u16 ax, bx;
+
+	ax = 0x0300;
+	bx = 0;
+	asm(INT10
+	    : "=d" (curpos), "+a" (ax), "+b" (bx)
+	    : : "ecx", "esi", "edi");
+
+	boot_params.screen_info.orig_x = curpos;
+	boot_params.screen_info.orig_y = curpos >> 8;
+}
+
+static void store_video_mode(void)
+{
+	u16 ax, page;
+
+	/* N.B.: the saving of the video page here is a bit silly,
+	   since we pretty much assume page 0 everywhere. */
+	ax = 0x0f00;
+	asm(INT10
+	    : "+a" (ax), "=b" (page)
+	    : : "ecx", "edx", "esi", "edi");
+
+	/* Not all BIOSes are clean with respect to the top bit */
+	boot_params.screen_info.orig_video_mode = ax & 0x7f;
+	boot_params.screen_info.orig_video_page = page;
+}
+
+/*
+ * Store the video mode parameters for later usage by the kernel.
+ * This is done by asking the BIOS except for the rows/columns
+ * parameters in the default 80x25 mode -- these are set directly,
+ * because some very obscure BIOSes supply insane values.
+ */
+static void store_mode_params(void)
+{
+	u16 font_size;
+	int x, y;
+
+	/* For graphics mode, it is up to the mode-setting driver
+	   (currently only video-vesa.c) to store the parameters */
+	if (graphic_mode)
+		return;
+
+	store_cursor_position();
+	store_video_mode();
+
+	if (boot_params.screen_info.orig_video_mode == 0x07) {
+		/* MDA, HGC, or VGA in monochrome mode */
+		video_segment = 0xb000;
+	} else {
+		/* CGA, EGA, VGA and so forth */
+		video_segment = 0xb800;
+	}
+
+	set_fs(0);
+	font_size = rdfs16(0x485); /* Font size, BIOS area */
+	boot_params.screen_info.orig_video_points = font_size;
+
+	x = rdfs16(0x44a);
+	y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(0x484)+1;
+
+	if (force_x)
+		x = force_x;
+	if (force_y)
+		y = force_y;
+
+	boot_params.screen_info.orig_video_cols  = x;
+	boot_params.screen_info.orig_video_lines = y;
+}
+
+/* Probe the video drivers and have them generate their mode lists. */
+static void probe_cards(int unsafe)
+{
+	struct card_info *card;
+	static u8 probed[2];
+
+	if (probed[unsafe])
+		return;
+
+	probed[unsafe] = 1;
+
+	for (card = video_cards; card < video_cards_end; card++) {
+		if (card->unsafe == unsafe) {
+			if (card->probe)
+				card->nmodes = card->probe();
+			else
+				card->nmodes = 0;
+		}
+	}
+}
+
+/* Test if a mode is defined */
+int mode_defined(u16 mode)
+{
+	struct card_info *card;
+	struct mode_info *mi;
+	int i;
+
+	for (card = video_cards; card < video_cards_end; card++) {
+		mi = card->modes;
+		for (i = 0; i < card->nmodes; i++, mi++) {
+			if (mi->mode == mode)
+				return 1;
+		}
+	}
+
+	return 0;
+}
+
+/* Set mode (without recalc) */
+static int raw_set_mode(u16 mode)
+{
+	int nmode, i;
+	struct card_info *card;
+	struct mode_info *mi;
+
+	/* Drop the recalc bit if set */
+	mode &= ~VIDEO_RECALC;
+
+	/* Scan for mode based on fixed ID, position, or resolution */
+	nmode = 0;
+	for (card = video_cards; card < video_cards_end; card++) {
+		mi = card->modes;
+		for (i = 0; i < card->nmodes; i++, mi++) {
+			int visible = mi->x || mi->y;
+
+			if ((mode == nmode && visible) ||
+			    mode == mi->mode ||
+			    mode == (mi->y << 8)+mi->x)
+				return card->set_mode(mi);
+
+			if (visible)
+				nmode++;
+		}
+	}
+
+	/* Nothing found?  Is it an "exceptional" (unprobed) mode? */
+	for (card = video_cards; card < video_cards_end; card++) {
+		if (mode >= card->xmode_first &&
+		    mode < card->xmode_first+card->xmode_n) {
+			struct mode_info mix;
+			mix.mode = mode;
+			mix.x = mix.y = 0;
+			return card->set_mode(&mix);
+		}
+	}
+
+	/* Otherwise, failure... */
+	return -1;
+}
+
+/*
+ * Recalculate the vertical video cutoff (hack!)
+ */
+static void vga_recalc_vertical(void)
+{
+	unsigned int font_size, rows;
+	u16 crtc;
+	u8 ov;
+
+	set_fs(0);
+	font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
+	rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
+
+	rows *= font_size;	/* Visible scan lines */
+	rows--;			/* ... minus one */
+
+	crtc = vga_crtc();
+
+	out_idx((u8)rows, crtc, 0x12); /* Lower height register */
+	ov = in_idx(crtc, 0x07); /* Overflow register */
+	ov &= 0xbd;
+	ov |= (rows >> (8-1)) & 0x02;
+	ov |= (rows >> (9-6)) & 0x40;
+	out_idx(ov, crtc, 0x07);
+}
+
+/* Set mode (with recalc if specified) */
+static int set_mode(u16 mode)
+{
+	int rv;
+
+	/* Very special mode numbers... */
+	if (mode == VIDEO_CURRENT_MODE)
+		return 0;	/* Nothing to do... */
+	else if (mode == NORMAL_VGA)
+		mode = VIDEO_80x25;
+	else if (mode == EXTENDED_VGA)
+		mode = VIDEO_8POINT;
+
+	rv = raw_set_mode(mode);
+	if (rv)
+		return rv;
+
+	if (mode & VIDEO_RECALC)
+		vga_recalc_vertical();
+
+	return 0;
+}
+
+static unsigned int get_entry(void)
+{
+	char entry_buf[4];
+	int i, len = 0;
+	int key;
+	unsigned int v;
+
+	do {
+		key = getchar();
+
+		if (key == '\b') {
+			if (len > 0) {
+				puts("\b \b");
+				len--;
+			}
+		} else if ((key >= '0' && key <= '9') ||
+			   (key >= 'A' && key <= 'Z') ||
+			   (key >= 'a' && key <= 'z')) {
+			if (len < sizeof entry_buf) {
+				entry_buf[len++] = key;
+				putchar(key);
+			}
+		}
+	} while (key != '\r');
+	putchar('\n');
+
+	if (len == 0)
+		return VIDEO_CURRENT_MODE; /* Default */
+
+	v = 0;
+	for (i = 0; i < len; i++) {
+		v <<= 4;
+		key = entry_buf[i] | 0x20;
+		v += (key > '9') ? key-'a'+10 : key-'0';
+	}
+
+	return v;
+}
+
+static void display_menu(void)
+{
+	struct card_info *card;
+	struct mode_info *mi;
+	char ch;
+	int i;
+
+	puts("Mode:    COLSxROWS:\n");
+
+	ch = '0';
+	for (card = video_cards; card < video_cards_end; card++) {
+		mi = card->modes;
+		for (i = 0; i < card->nmodes; i++, mi++) {
+			int visible = mi->x && mi->y;
+			u16 mode_id = mi->mode ? mi->mode :
+				(mi->y << 8)+mi->x;
+
+			if (!visible)
+				continue; /* Hidden mode */
+
+			printf("%c  %04X  %3dx%-3d  %s\n",
+			       ch, mode_id, mi->x, mi->y, card->card_name);
+
+			if (ch == '9')
+				ch = 'a';
+			else if (ch == 'z' || ch == ' ')
+				ch = ' '; /* Out of keys... */
+			else
+				ch++;
+		}
+	}
+}
+
+#define H(x)	((x)-'a'+10)
+#define SCAN	((H('s')<<12)+(H('c')<<8)+(H('a')<<4)+H('n'))
+
+static unsigned int mode_menu(void)
+{
+	int key;
+	unsigned int sel;
+
+	puts("Press <ENTER> to see video modes available, "
+	     "<SPACE> to continue, or wait 30 sec\n");
+
+	kbd_flush();
+	while (1) {
+		key = getchar_timeout();
+		if (key == ' ' || key == 0)
+			return VIDEO_CURRENT_MODE; /* Default */
+		if (key == '\r')
+			break;
+		putchar('\a');	/* Beep! */
+	}
+
+
+	for (;;) {
+		display_menu();
+
+		puts("Enter a video mode or \"scan\" to scan for "
+		     "additional modes: ");
+		sel = get_entry();
+		if (sel != SCAN)
+			return sel;
+
+		probe_cards(1);
+	}
+}
+
+#ifdef CONFIG_VIDEO_RETAIN
+/* Save screen content to the heap */
+struct saved_screen {
+	int x, y;
+	int curx, cury;
+	u16 *data;
+} saved;
+
+static void save_screen(void)
+{
+	/* Should be called after store_mode_params() */
+	saved.x = boot_params.screen_info.orig_video_cols;
+	saved.y = boot_params.screen_info.orig_video_lines;
+	saved.curx = boot_params.screen_info.orig_x;
+	saved.cury = boot_params.screen_info.orig_y;
+
+	if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
+		return;		/* Not enough heap to save the screen */
+
+	saved.data = GET_HEAP(u16, saved.x*saved.y);
+
+	set_fs(video_segment);
+	copy_from_fs(saved.data, 0, saved.x*saved.y*sizeof(u16));
+}
+
+static void restore_screen(void)
+{
+	/* Should be called after store_mode_params() */
+	int xs = boot_params.screen_info.orig_video_cols;
+	int ys = boot_params.screen_info.orig_video_lines;
+	int y;
+	addr_t dst = 0;
+	u16 *src = saved.data;
+	u16 ax, bx, dx;
+
+	if (graphic_mode)
+		return;		/* Can't restore onto a graphic mode */
+
+	if (!src)
+		return;		/* No saved screen contents */
+
+	/* Restore screen contents */
+
+	set_fs(video_segment);
+	for (y = 0; y < ys; y++) {
+		int npad;
+
+		if (y < saved.y) {
+			int copy = (xs < saved.x) ? xs : saved.x;
+			copy_to_fs(dst, src, copy*sizeof(u16));
+			dst += copy*sizeof(u16);
+			src += saved.x;
+			npad = (xs < saved.x) ? 0 : xs-saved.x;
+		} else {
+			npad = xs;
+		}
+
+		/* Writes "npad" blank characters to
+		   video_segment:dst and advances dst */
+		asm volatile("pushw %%es ; "
+			     "movw %2,%%es ; "
+			     "shrw %%cx ; "
+			     "jnc 1f ; "
+			     "stosw \n\t"
+			     "1: rep;stosl ; "
+			     "popw %%es"
+			     : "+D" (dst), "+c" (npad)
+			     : "bdSm" (video_segment),
+			       "a" (0x07200720));
+	}
+
+	/* Restore cursor position */
+	ax = 0x0200;		/* Set cursor position */
+	bx = 0;			/* Page number (<< 8) */
+	dx = (saved.cury << 8)+saved.curx;
+	asm volatile(INT10
+		     : "+a" (ax), "+b" (bx), "+d" (dx)
+		     : : "ecx", "esi", "edi");
+}
+#else
+#define save_screen()		((void)0)
+#define restore_screen()	((void)0)
+#endif
+
+void set_video(void)
+{
+	u16 mode = boot_params.hdr.vid_mode;
+
+	RESET_HEAP();
+
+	store_mode_params();
+	save_screen();
+	probe_cards(0);
+
+	for (;;) {
+		if (mode == ASK_VGA)
+			mode = mode_menu();
+
+		if (!set_mode(mode))
+			break;
+
+		printf("Undefined video mode number: %x\n", mode);
+		mode = ASK_VGA;
+	}
+	vesa_store_edid();
+	store_mode_params();
+
+	if (do_restore)
+		restore_screen();
+}