diff options
Diffstat (limited to 'arch/i386/boot/video-bios.c')
-rw-r--r-- | arch/i386/boot/video-bios.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/arch/i386/boot/video-bios.c b/arch/i386/boot/video-bios.c new file mode 100644 index 00000000000..afea46c500c --- /dev/null +++ b/arch/i386/boot/video-bios.c @@ -0,0 +1,125 @@ +/* -*- 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-bios.c + * + * Standard video BIOS modes + * + * We have two options for this; silent and scanned. + */ + +#include "boot.h" +#include "video.h" + +__videocard video_bios; + +/* Set a conventional BIOS mode */ +static int set_bios_mode(u8 mode); + +static int bios_set_mode(struct mode_info *mi) +{ + return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS); +} + +static int set_bios_mode(u8 mode) +{ + u16 ax; + u8 new_mode; + + ax = mode; /* AH=0x00 Set Video Mode */ + asm volatile(INT10 + : "+a" (ax) + : : "ebx", "ecx", "edx", "esi", "edi"); + + ax = 0x0f00; /* Get Current Video Mode */ + asm volatile(INT10 + : "+a" (ax) + : : "ebx", "ecx", "edx", "esi", "edi"); + + do_restore = 1; /* Assume video contents was lost */ + new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */ + + if (new_mode == mode) + return 0; /* Mode change OK */ + + if (new_mode != boot_params.screen_info.orig_video_mode) { + /* Mode setting failed, but we didn't end up where we + started. That's bad. Try to revert to the original + video mode. */ + ax = boot_params.screen_info.orig_video_mode; + asm volatile(INT10 + : "+a" (ax) + : : "ebx", "ecx", "edx", "esi", "edi"); + } + return -1; +} + +static int bios_probe(void) +{ + u8 mode; + u8 saved_mode = boot_params.screen_info.orig_video_mode; + u16 crtc; + struct mode_info *mi; + int nmodes = 0; + + if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA) + return 0; + + set_fs(0); + crtc = vga_crtc(); + + video_bios.modes = GET_HEAP(struct mode_info, 0); + + for (mode = 0x14; mode <= 0x7f; mode++) { + if (heap_free() < sizeof(struct mode_info)) + break; + + if (mode_defined(VIDEO_FIRST_BIOS+mode)) + continue; + + if (set_bios_mode(mode)) + continue; + + /* Try to verify that it's a text mode. */ + + /* Attribute Controller: make graphics controller disabled */ + if (in_idx(0x3c0, 0x10) & 0x01) + continue; + + /* Graphics Controller: verify Alpha addressing enabled */ + if (in_idx(0x3ce, 0x06) & 0x01) + continue; + + /* CRTC cursor location low should be zero(?) */ + if (in_idx(crtc, 0x0f)) + continue; + + mi = GET_HEAP(struct mode_info, 1); + mi->mode = VIDEO_FIRST_BIOS+mode; + mi->x = rdfs16(0x44a); + mi->y = rdfs8(0x484)+1; + nmodes++; + } + + set_bios_mode(saved_mode); + + return nmodes; +} + +__videocard video_bios = +{ + .card_name = "BIOS (scanned)", + .probe = bios_probe, + .set_mode = bios_set_mode, + .unsafe = 1, + .xmode_first = VIDEO_FIRST_BIOS, + .xmode_n = 0x80, +}; |