126 lines
2.8 KiB
C
126 lines
2.8 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-bios.c
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*
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* Standard video BIOS modes
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*
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* We have two options for this; silent and scanned.
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*/
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#include "boot.h"
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#include "video.h"
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__videocard video_bios;
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/* Set a conventional BIOS mode */
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static int set_bios_mode(u8 mode);
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static int bios_set_mode(struct mode_info *mi)
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{
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return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS);
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}
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static int set_bios_mode(u8 mode)
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{
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u16 ax;
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u8 new_mode;
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ax = mode; /* AH=0x00 Set Video Mode */
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asm volatile(INT10
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: "+a" (ax)
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: : "ebx", "ecx", "edx", "esi", "edi");
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ax = 0x0f00; /* Get Current Video Mode */
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asm volatile(INT10
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: "+a" (ax)
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: : "ebx", "ecx", "edx", "esi", "edi");
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do_restore = 1; /* Assume video contents were lost */
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new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */
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if (new_mode == mode)
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return 0; /* Mode change OK */
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if (new_mode != boot_params.screen_info.orig_video_mode) {
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/* Mode setting failed, but we didn't end up where we
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started. That's bad. Try to revert to the original
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video mode. */
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ax = boot_params.screen_info.orig_video_mode;
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asm volatile(INT10
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: "+a" (ax)
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: : "ebx", "ecx", "edx", "esi", "edi");
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}
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return -1;
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}
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static int bios_probe(void)
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{
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u8 mode;
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u8 saved_mode = boot_params.screen_info.orig_video_mode;
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u16 crtc;
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struct mode_info *mi;
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int nmodes = 0;
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if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA)
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return 0;
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set_fs(0);
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crtc = vga_crtc();
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video_bios.modes = GET_HEAP(struct mode_info, 0);
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for (mode = 0x14; mode <= 0x7f; mode++) {
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if (heap_free() < sizeof(struct mode_info))
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break;
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if (mode_defined(VIDEO_FIRST_BIOS+mode))
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continue;
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if (set_bios_mode(mode))
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continue;
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/* Try to verify that it's a text mode. */
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/* Attribute Controller: make graphics controller disabled */
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if (in_idx(0x3c0, 0x10) & 0x01)
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continue;
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/* Graphics Controller: verify Alpha addressing enabled */
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if (in_idx(0x3ce, 0x06) & 0x01)
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continue;
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/* CRTC cursor location low should be zero(?) */
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if (in_idx(crtc, 0x0f))
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continue;
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mi = GET_HEAP(struct mode_info, 1);
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mi->mode = VIDEO_FIRST_BIOS+mode;
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mi->x = rdfs16(0x44a);
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mi->y = rdfs8(0x484)+1;
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nmodes++;
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}
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set_bios_mode(saved_mode);
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return nmodes;
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}
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__videocard video_bios =
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{
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.card_name = "BIOS (scanned)",
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.probe = bios_probe,
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.set_mode = bios_set_mode,
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.unsafe = 1,
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.xmode_first = VIDEO_FIRST_BIOS,
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.xmode_n = 0x80,
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};
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