// 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
 *
 * ----------------------------------------------------------------------- */

/*
 * Select video mode
 */

#include <uapi/asm/boot.h>

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

static u16 video_segment;

static void store_cursor_position(void)
{
        struct biosregs ireg, oreg;

        initregs(&ireg);
        ireg.ah = 0x03;
        intcall(0x10, &ireg, &oreg);

        boot_params.screen_info.orig_x = oreg.dl;
        boot_params.screen_info.orig_y = oreg.dh;

        if (oreg.ch & 0x20)
                boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;

        if ((oreg.ch & 0x1f) > (oreg.cl & 0x1f))
                boot_params.screen_info.flags |= VIDEO_FLAGS_NOCURSOR;
}

static void store_video_mode(void)
{
        struct biosregs ireg, oreg;

        /* N.B.: the saving of the video page here is a bit silly,
           since we pretty much assume page 0 everywhere. */
        initregs(&ireg);
        ireg.ah = 0x0f;
        intcall(0x10, &ireg, &oreg);

        /* Not all BIOSes are clean with respect to the top bit */
        boot_params.screen_info.orig_video_mode = oreg.al & 0x7f;
        boot_params.screen_info.orig_video_page = oreg.bh;
}

/*
 * Store the video mode parameters for later usage by the kernel.
 * This is done by asking the BIOS except for the rows/columns
 * parameters in the default 80x25 mode -- these are set directly,
 * because some very obscure BIOSes supply insane values.
 */
static void store_mode_params(void)
{
        u16 font_size;
        int x, y;

        /* For graphics mode, it is up to the mode-setting driver
           (currently only video-vesa.c) to store the parameters */
        if (graphic_mode)
                return;

        store_cursor_position();
        store_video_mode();

        if (boot_params.screen_info.orig_video_mode == 0x07) {
                /* MDA, HGC, or VGA in monochrome mode */
                video_segment = 0xb000;
        } else {
                /* CGA, EGA, VGA and so forth */
                video_segment = 0xb800;
        }

        set_fs(0);
        font_size = rdfs16(0x485); /* Font size, BIOS area */
        boot_params.screen_info.orig_video_points = font_size;

        x = rdfs16(0x44a);
        y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(0x484)+1;

        if (force_x)
                x = force_x;
        if (force_y)
                y = force_y;

        boot_params.screen_info.orig_video_cols  = x;
        boot_params.screen_info.orig_video_lines = y;
}

static unsigned int get_entry(void)
{
        char entry_buf[4];
        int i, len = 0;
        int key;
        unsigned int v;

        do {
                key = getchar();

                if (key == '\b') {
                        if (len > 0) {
                                puts("\b \b");
                                len--;
                        }
                } else if ((key >= '0' && key <= '9') ||
                           (key >= 'A' && key <= 'Z') ||
                           (key >= 'a' && key <= 'z')) {
                        if (len < sizeof(entry_buf)) {
                                entry_buf[len++] = key;
                                putchar(key);
                        }
                }
        } while (key != '\r');
        putchar('\n');

        if (len == 0)
                return VIDEO_CURRENT_MODE; /* Default */

        v = 0;
        for (i = 0; i < len; i++) {
                v <<= 4;
                key = entry_buf[i] | 0x20;
                v += (key > '9') ? key-'a'+10 : key-'0';
        }

        return v;
}

static void display_menu(void)
{
        struct card_info *card;
        struct mode_info *mi;
        char ch;
        int i;
        int nmodes;
        int modes_per_line;
        int col;

        nmodes = 0;
        for (card = video_cards; card < video_cards_end; card++)
                nmodes += card->nmodes;

        modes_per_line = 1;
        if (nmodes >= 20)
                modes_per_line = 3;

        for (col = 0; col < modes_per_line; col++)
                puts("Mode: Resolution:  Type: ");
        putchar('\n');

        col = 0;
        ch = '0';
        for (card = video_cards; card < video_cards_end; card++) {
                mi = card->modes;
                for (i = 0; i < card->nmodes; i++, mi++) {
                        char resbuf[32];
                        int visible = mi->x && mi->y;
                        u16 mode_id = mi->mode ? mi->mode :
                                (mi->y << 8)+mi->x;

                        if (!visible)
                                continue; /* Hidden mode */

                        if (mi->depth)
                                sprintf(resbuf, "%dx%d", mi->y, mi->depth);
                        else
                                sprintf(resbuf, "%d", mi->y);

                        printf("%c %03X %4dx%-7s %-6s",
                               ch, mode_id, mi->x, resbuf, card->card_name);
                        col++;
                        if (col >= modes_per_line) {
                                putchar('\n');
                                col = 0;
                        }

                        if (ch == '9')
                                ch = 'a';
                        else if (ch == 'z' || ch == ' ')
                                ch = ' '; /* Out of keys... */
                        else
                                ch++;
                }
        }
        if (col)
                putchar('\n');
}

#define H(x)    ((x)-'a'+10)
#define SCAN    ((H('s')<<12)+(H('c')<<8)+(H('a')<<4)+H('n'))

static unsigned int mode_menu(void)
{
        int key;
        unsigned int sel;

        puts("Press <ENTER> to see video modes available, "
             "<SPACE> to continue, or wait 30 sec\n");

        kbd_flush();
        while (1) {
                key = getchar_timeout();
                if (key == ' ' || key == 0)
                        return VIDEO_CURRENT_MODE; /* Default */
                if (key == '\r')
                        break;
                putchar('\a');  /* Beep! */
        }


        for (;;) {
                display_menu();

                puts("Enter a video mode or \"scan\" to scan for "
                     "additional modes: ");
                sel = get_entry();
                if (sel != SCAN)
                        return sel;

                probe_cards(1);
        }
}

/* Save screen content to the heap */
static struct saved_screen {
        int x, y;
        int curx, cury;
        u16 *data;
} saved;

static void save_screen(void)
{
        /* Should be called after store_mode_params() */
        saved.x = boot_params.screen_info.orig_video_cols;
        saved.y = boot_params.screen_info.orig_video_lines;
        saved.curx = boot_params.screen_info.orig_x;
        saved.cury = boot_params.screen_info.orig_y;

        if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
                return;         /* Not enough heap to save the screen */

        saved.data = GET_HEAP(u16, saved.x*saved.y);

        set_fs(video_segment);
        copy_from_fs(saved.data, 0, saved.x*saved.y*sizeof(u16));
}

static void restore_screen(void)
{
        /* Should be called after store_mode_params() */
        int xs = boot_params.screen_info.orig_video_cols;
        int ys = boot_params.screen_info.orig_video_lines;
        int y;
        addr_t dst = 0;
        u16 *src = saved.data;
        struct biosregs ireg;

        if (graphic_mode)
                return;         /* Can't restore onto a graphic mode */

        if (!src)
                return;         /* No saved screen contents */

        /* Restore screen contents */

        set_fs(video_segment);
        for (y = 0; y < ys; y++) {
                int npad;

                if (y < saved.y) {
                        int copy = (xs < saved.x) ? xs : saved.x;
                        copy_to_fs(dst, src, copy*sizeof(u16));
                        dst += copy*sizeof(u16);
                        src += saved.x;
                        npad = (xs < saved.x) ? 0 : xs-saved.x;
                } else {
                        npad = xs;
                }

                /* Writes "npad" blank characters to
                   video_segment:dst and advances dst */
                asm volatile("pushw %%es ; "
                             "movw %2,%%es ; "
                             "shrw %%cx ; "
                             "jnc 1f ; "
                             "stosw \n\t"
                             "1: rep;stosl ; "
                             "popw %%es"
                             : "+D" (dst), "+c" (npad)
                             : "bdS" (video_segment),
                               "a" (0x07200720));
        }

        /* Restore cursor position */
        if (saved.curx >= xs)
                saved.curx = xs-1;
        if (saved.cury >= ys)
                saved.cury = ys-1;

        initregs(&ireg);
        ireg.ah = 0x02;         /* Set cursor position */
        ireg.dh = saved.cury;
        ireg.dl = saved.curx;
        intcall(0x10, &ireg, NULL);

        store_cursor_position();
}

void set_video(void)
{
        u16 mode = boot_params.hdr.vid_mode;

        RESET_HEAP();

        store_mode_params();
        save_screen();
        probe_cards(0);

        for (;;) {
                if (mode == ASK_VGA)
                        mode = mode_menu();

                if (!set_mode(mode))
                        break;

                printf("Undefined video mode number: %x\n", mode);
                mode = ASK_VGA;
        }
        boot_params.hdr.vid_mode = mode;
        vesa_store_edid();
        store_mode_params();

        if (do_restore)
                restore_screen();
}