8c027ae2dc
There exists at least one card, Trident TVGA8900CL (BIOS dated 1992/9/8) which clobbers DS when "scrolling in an SVGA text mode of more than 800x600 pixels." Although we are extremely unlikely to run into that situation, it is cheap insurance to save and restore DS, and it only adds a grand total of 50 bytes to the total output. Pointed out by Etienne Lorrain. Cc: Etienne Lorrain <etienne_lorrain@yahoo.fr> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
152 lines
4.3 KiB
C
152 lines
4.3 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* arch/i386/boot/video.h
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*
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* Header file for the real-mode video probing code
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*/
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#ifndef BOOT_VIDEO_H
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#define BOOT_VIDEO_H
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#include <linux/types.h>
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/* Enable autodetection of SVGA adapters and modes. */
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#undef CONFIG_VIDEO_SVGA
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/* Enable autodetection of VESA modes */
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#define CONFIG_VIDEO_VESA
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/* Retain screen contents when switching modes */
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#define CONFIG_VIDEO_RETAIN
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/* Force 400 scan lines for standard modes (hack to fix bad BIOS behaviour */
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#undef CONFIG_VIDEO_400_HACK
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/* This code uses an extended set of video mode numbers. These include:
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* Aliases for standard modes
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* NORMAL_VGA (-1)
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* EXTENDED_VGA (-2)
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* ASK_VGA (-3)
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* Video modes numbered by menu position -- NOT RECOMMENDED because of lack
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* of compatibility when extending the table. These are between 0x00 and 0xff.
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*/
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#define VIDEO_FIRST_MENU 0x0000
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/* Standard BIOS video modes (BIOS number + 0x0100) */
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#define VIDEO_FIRST_BIOS 0x0100
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/* VESA BIOS video modes (VESA number + 0x0200) */
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#define VIDEO_FIRST_VESA 0x0200
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/* Video7 special modes (BIOS number + 0x0900) */
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#define VIDEO_FIRST_V7 0x0900
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/* Special video modes */
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#define VIDEO_FIRST_SPECIAL 0x0f00
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#define VIDEO_80x25 0x0f00
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#define VIDEO_8POINT 0x0f01
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#define VIDEO_80x43 0x0f02
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#define VIDEO_80x28 0x0f03
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#define VIDEO_CURRENT_MODE 0x0f04
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#define VIDEO_80x30 0x0f05
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#define VIDEO_80x34 0x0f06
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#define VIDEO_80x60 0x0f07
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#define VIDEO_GFX_HACK 0x0f08
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#define VIDEO_LAST_SPECIAL 0x0f09
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/* Video modes given by resolution */
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#define VIDEO_FIRST_RESOLUTION 0x1000
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/* The "recalculate timings" flag */
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#define VIDEO_RECALC 0x8000
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/* Define DO_STORE according to CONFIG_VIDEO_RETAIN */
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#ifdef CONFIG_VIDEO_RETAIN
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void store_screen(void);
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#define DO_STORE() store_screen()
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#else
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#define DO_STORE() ((void)0)
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#endif /* CONFIG_VIDEO_RETAIN */
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/*
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* Mode table structures
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*/
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struct mode_info {
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u16 mode; /* Mode number (vga= style) */
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u8 x, y; /* Width, height */
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};
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struct card_info {
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const char *card_name;
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int (*set_mode)(struct mode_info *mode);
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int (*probe)(void);
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struct mode_info *modes;
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int nmodes; /* Number of probed modes so far */
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int unsafe; /* Probing is unsafe, only do after "scan" */
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u16 xmode_first; /* Unprobed modes to try to call anyway */
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u16 xmode_n; /* Size of unprobed mode range */
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};
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#define __videocard struct card_info __attribute__((section(".videocards")))
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extern struct card_info video_cards[], video_cards_end[];
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int mode_defined(u16 mode); /* video.c */
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/* Basic video information */
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#define ADAPTER_CGA 0 /* CGA/MDA/HGC */
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#define ADAPTER_EGA 1
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#define ADAPTER_VGA 2
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extern int adapter;
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extern u16 video_segment;
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extern int force_x, force_y; /* Don't query the BIOS for cols/rows */
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extern int do_restore; /* Restore screen contents */
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extern int graphic_mode; /* Graphics mode with linear frame buffer */
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/*
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* int $0x10 is notorious for touching registers it shouldn't.
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* gcc doesn't like %ebp being clobbered, so define it as a push/pop
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* sequence here.
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*
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* A number of systems, including the original PC can clobber %bp in
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* certain circumstances, like when scrolling. There exists at least
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* one Trident video card which could clobber DS under a set of
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* circumstances that we are unlikely to encounter (scrolling when
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* using an extended graphics mode of more than 800x600 pixels), but
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* it's cheap insurance to deal with that here.
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*/
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#define INT10 "pushl %%ebp; pushw %%ds; int $0x10; popw %%ds; popl %%ebp"
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/* Accessing VGA indexed registers */
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static inline u8 in_idx(u16 port, u8 index)
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{
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outb(index, port);
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return inb(port+1);
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}
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static inline void out_idx(u8 v, u16 port, u8 index)
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{
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outw(index+(v << 8), port);
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}
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/* Writes a value to an indexed port and then reads the port again */
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static inline u8 tst_idx(u8 v, u16 port, u8 index)
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{
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out_idx(port, index, v);
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return in_idx(port, index);
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}
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/* Get the I/O port of the VGA CRTC */
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u16 vga_crtc(void); /* video-vga.c */
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#endif /* BOOT_VIDEO_H */
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