video-vga.c

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/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
 *
 *   This file is part of the Linux kernel, and is made available under
 *   the terms of the GNU General Public License version 2.
 *
 * ----------------------------------------------------------------------- */

/*
 * Common all-VGA modes
 */

#include "boot.h"
#include "video.h"

static struct mode_info vga_modes[] = {
    { VIDEO_80x25,  80, 25, 0 },
    { VIDEO_8POINT, 80, 50, 0 },
    { VIDEO_80x43,  80, 43, 0 },
    { VIDEO_80x28,  80, 28, 0 },
    { VIDEO_80x30,  80, 30, 0 },
    { VIDEO_80x34,  80, 34, 0 },
    { VIDEO_80x60,  80, 60, 0 },
};

static struct mode_info ega_modes[] = {
    { VIDEO_80x25,  80, 25, 0 },
    { VIDEO_8POINT, 80, 43, 0 },
};

static struct mode_info cga_modes[] = {
    { VIDEO_80x25,  80, 25, 0 },
};

static __videocard video_vga;

/* Set basic 80x25 mode */
static u8 vga_set_basic_mode(void)
{
    struct biosregs ireg, oreg;
    u8 mode;

    initregs(&ireg);

    /* Query current mode */
    ireg.ax = 0x0f00;
    intcall(0x10, &ireg, &oreg);
    mode = oreg.al;

    if (mode != 3 && mode != 7)
        mode = 3;

    /* Set the mode */
    ireg.ax = mode;     /* AH=0: set mode */
    intcall(0x10, &ireg, NULL);
    do_restore = 1;
    return mode;
}

static void vga_set_8font(void)
{
    /* Set 8x8 font - 80x43 on EGA, 80x50 on VGA */
    struct biosregs ireg;

    initregs(&ireg);

    /* Set 8x8 font */
    ireg.ax = 0x1112;
    /* ireg.bl = 0; */
    intcall(0x10, &ireg, NULL);

    /* Use alternate print screen */
    ireg.ax = 0x1200;
    ireg.bl = 0x20;
    intcall(0x10, &ireg, NULL);

    /* Turn off cursor emulation */
    ireg.ax = 0x1201;
    ireg.bl = 0x34;
    intcall(0x10, &ireg, NULL);

    /* Cursor is scan lines 6-7 */
    ireg.ax = 0x0100;
    ireg.cx = 0x0607;
    intcall(0x10, &ireg, NULL);
}

static void vga_set_14font(void)
{
    /* Set 9x14 font - 80x28 on VGA */
    struct biosregs ireg;

    initregs(&ireg);

    /* Set 9x14 font */
    ireg.ax = 0x1111;
    /* ireg.bl = 0; */
    intcall(0x10, &ireg, NULL);

    /* Turn off cursor emulation */
    ireg.ax = 0x1201;
    ireg.bl = 0x34;
    intcall(0x10, &ireg, NULL);

    /* Cursor is scan lines 11-12 */
    ireg.ax = 0x0100;
    ireg.cx = 0x0b0c;
    intcall(0x10, &ireg, NULL);
}

static void vga_set_80x43(void)
{
    /* Set 80x43 mode on VGA (not EGA) */
    struct biosregs ireg;

    initregs(&ireg);

    /* Set 350 scans */
    ireg.ax = 0x1201;
    ireg.bl = 0x30;
    intcall(0x10, &ireg, NULL);

    /* Reset video mode */
    ireg.ax = 0x0003;
    intcall(0x10, &ireg, NULL);

    vga_set_8font();
}

/* I/O address of the VGA CRTC */
u16 vga_crtc(void)
{
    return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
}

static void vga_set_480_scanlines(void)
{
    u16 crtc;       /* CRTC base address */
    u8  csel;       /* CRTC miscellaneous output register */

    crtc = vga_crtc();

    out_idx(0x0c, crtc, 0x11); /* Vertical sync end, unlock CR0-7 */
    out_idx(0x0b, crtc, 0x06); /* Vertical total */
    out_idx(0x3e, crtc, 0x07); /* Vertical overflow */
    out_idx(0xea, crtc, 0x10); /* Vertical sync start */
    out_idx(0xdf, crtc, 0x12); /* Vertical display end */
    out_idx(0xe7, crtc, 0x15); /* Vertical blank start */
    out_idx(0x04, crtc, 0x16); /* Vertical blank end */
    csel = inb(0x3cc);
    csel &= 0x0d;
    csel |= 0xe2;
    outb(csel, 0x3c2);
}

static void vga_set_vertical_end(int lines)
{
    u16 crtc;       /* CRTC base address */
    u8  ovfw;       /* CRTC overflow register */
    int end = lines-1;

    crtc = vga_crtc();

    ovfw = 0x3c | ((end >> (8-1)) & 0x02) | ((end >> (9-6)) & 0x40);

    out_idx(ovfw, crtc, 0x07); /* Vertical overflow */
    out_idx(end,  crtc, 0x12); /* Vertical display end */
}

static void vga_set_80x30(void)
{
    vga_set_480_scanlines();
    vga_set_vertical_end(30*16);
}

static void vga_set_80x34(void)
{
    vga_set_480_scanlines();
    vga_set_14font();
    vga_set_vertical_end(34*14);
}

static void vga_set_80x60(void)
{
    vga_set_480_scanlines();
    vga_set_8font();
    vga_set_vertical_end(60*8);
}

static int vga_set_mode(struct mode_info *mode)
{
    /* Set the basic mode */
    vga_set_basic_mode();

    /* Override a possibly broken BIOS */
    force_x = mode->x;
    force_y = mode->y;

    switch (mode->mode) {
    case VIDEO_80x25:
        break;
    case VIDEO_8POINT:
        vga_set_8font();
        break;
    case VIDEO_80x43:
        vga_set_80x43();
        break;
    case VIDEO_80x28:
        vga_set_14font();
        break;
    case VIDEO_80x30:
        vga_set_80x30();
        break;
    case VIDEO_80x34:
        vga_set_80x34();
        break;
    case VIDEO_80x60:
        vga_set_80x60();
        break;
    }

    return 0;
}

/*
 * Note: this probe includes basic information required by all
 * systems.  It should be executed first, by making sure
 * video-vga.c is listed first in the Makefile.
 */
static int vga_probe(void)
{
    static const char *card_name[] = {
        "CGA/MDA/HGC", "EGA", "VGA"
    };
    static struct mode_info *mode_lists[] = {
        cga_modes,
        ega_modes,
        vga_modes,
    };
    static int mode_count[] = {
        sizeof(cga_modes)/sizeof(struct mode_info),
        sizeof(ega_modes)/sizeof(struct mode_info),
        sizeof(vga_modes)/sizeof(struct mode_info),
    };

    struct biosregs ireg, oreg;

    initregs(&ireg);

    ireg.ax = 0x1200;
    ireg.bl = 0x10;     /* Check EGA/VGA */
    intcall(0x10, &ireg, &oreg);

#ifndef _WAKEUP
    boot_params.screen_info.orig_video_ega_bx = oreg.bx;
#endif

    /* If we have MDA/CGA/HGC then BL will be unchanged at 0x10 */
    if (oreg.bl != 0x10) {
        /* EGA/VGA */
        ireg.ax = 0x1a00;
        intcall(0x10, &ireg, &oreg);

        if (oreg.al == 0x1a) {
            adapter = ADAPTER_VGA;
#ifndef _WAKEUP
            boot_params.screen_info.orig_video_isVGA = 1;
#endif
        } else {
            adapter = ADAPTER_EGA;
        }
    } else {
        adapter = ADAPTER_CGA;
    }

    video_vga.modes = mode_lists[adapter];
    video_vga.card_name = card_name[adapter];
    return mode_count[adapter];
}

static __videocard video_vga = {
    .card_name  = "VGA",
    .probe      = vga_probe,
    .set_mode   = vga_set_mode,
};