// SPDX-License-Identifier: GPL-2.0-only
/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
 *
 * ----------------------------------------------------------------------- */

/*
 * 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[] = {
                ARRAY_SIZE(cga_modes),
                ARRAY_SIZE(ega_modes),
                ARRAY_SIZE(vga_modes),
        };

        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,
};