/*
 * Copyright (C) 2013 Intel Corporation; author Matt Fleming
 *
 *  This file is part of the Linux kernel, and is made available under
 *  the terms of the GNU General Public License version 2.
 */

#include <linux/console.h>
#include <linux/efi.h>
#include <linux/font.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <asm/setup.h>

static const struct font_desc *font;
static u32 efi_x, efi_y;
static void *efi_fb;
static bool early_efi_keep;

/*
 * efi earlyprintk need use early_ioremap to map the framebuffer.
 * But early_ioremap is not usable for earlyprintk=efi,keep, ioremap should
 * be used instead. ioremap will be available after paging_init() which is
 * earlier than initcall callbacks. Thus adding this early initcall function
 * early_efi_map_fb to map the whole efi framebuffer.
 */
static __init int early_efi_map_fb(void)
{
        unsigned long base, size;

        if (!early_efi_keep)
                return 0;

        base = boot_params.screen_info.lfb_base;
        size = boot_params.screen_info.lfb_size;
        efi_fb = ioremap(base, size);

        return efi_fb ? 0 : -ENOMEM;
}
early_initcall(early_efi_map_fb);

/*
 * early_efi_map maps efi framebuffer region [start, start + len -1]
 * In case earlyprintk=efi,keep we have the whole framebuffer mapped already
 * so just return the offset efi_fb + start.
 */
static __ref void *early_efi_map(unsigned long start, unsigned long len)
{
        unsigned long base;

        base = boot_params.screen_info.lfb_base;

        if (efi_fb)
                return (efi_fb + start);
        else
                return early_ioremap(base + start, len);
}

static __ref void early_efi_unmap(void *addr, unsigned long len)
{
        if (!efi_fb)
                early_iounmap(addr, len);
}

static void early_efi_clear_scanline(unsigned int y)
{
        unsigned long *dst;
        u16 len;

        len = boot_params.screen_info.lfb_linelength;
        dst = early_efi_map(y*len, len);
        if (!dst)
                return;

        memset(dst, 0, len);
        early_efi_unmap(dst, len);
}

static void early_efi_scroll_up(void)
{
        unsigned long *dst, *src;
        u16 len;
        u32 i, height;

        len = boot_params.screen_info.lfb_linelength;
        height = boot_params.screen_info.lfb_height;

        for (i = 0; i < height - font->height; i++) {
                dst = early_efi_map(i*len, len);
                if (!dst)
                        return;

                src = early_efi_map((i + font->height) * len, len);
                if (!src) {
                        early_efi_unmap(dst, len);
                        return;
                }

                memmove(dst, src, len);

                early_efi_unmap(src, len);
                early_efi_unmap(dst, len);
        }
}

static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
{
        const u32 color_black = 0x00000000;
        const u32 color_white = 0x00ffffff;
        const u8 *src;
        u8 s8;
        int m;

        src = font->data + c * font->height;
        s8 = *(src + h);

        for (m = 0; m < 8; m++) {
                if ((s8 >> (7 - m)) & 1)
                        *dst = color_white;
                else
                        *dst = color_black;
                dst++;
        }
}

static void
early_efi_write(struct console *con, const char *str, unsigned int num)
{
        struct screen_info *si;
        unsigned int len;
        const char *s;
        void *dst;

        si = &boot_params.screen_info;
        len = si->lfb_linelength;

        while (num) {
                unsigned int linemax;
                unsigned int h, count = 0;

                for (s = str; *s && *s != '\n'; s++) {
                        if (count == num)
                                break;
                        count++;
                }

                linemax = (si->lfb_width - efi_x) / font->width;
                if (count > linemax)
                        count = linemax;

                for (h = 0; h < font->height; h++) {
                        unsigned int n, x;

                        dst = early_efi_map((efi_y + h) * len, len);
                        if (!dst)
                                return;

                        s = str;
                        n = count;
                        x = efi_x;

                        while (n-- > 0) {
                                early_efi_write_char(dst + x*4, *s, h);
                                x += font->width;
                                s++;
                        }

                        early_efi_unmap(dst, len);
                }

                num -= count;
                efi_x += count * font->width;
                str += count;

                if (num > 0 && *s == '\n') {
                        efi_x = 0;
                        efi_y += font->height;
                        str++;
                        num--;
                }

                if (efi_x >= si->lfb_width) {
                        efi_x = 0;
                        efi_y += font->height;
                }

                if (efi_y + font->height > si->lfb_height) {
                        u32 i;

                        efi_y -= font->height;
                        early_efi_scroll_up();

                        for (i = 0; i < font->height; i++)
                                early_efi_clear_scanline(efi_y + i);
                }
        }
}

static __init int early_efi_setup(struct console *con, char *options)
{
        struct screen_info *si;
        u16 xres, yres;
        u32 i;

        si = &boot_params.screen_info;
        xres = si->lfb_width;
        yres = si->lfb_height;

        /*
         * early_efi_write_char() implicitly assumes a framebuffer with
         * 32-bits per pixel.
         */
        if (si->lfb_depth != 32)
                return -ENODEV;

        font = get_default_font(xres, yres, -1, -1);
        if (!font)
                return -ENODEV;

        efi_y = rounddown(yres, font->height) - font->height;
        for (i = 0; i < (yres - efi_y) / font->height; i++)
                early_efi_scroll_up();

        /* early_console_register will unset CON_BOOT in case ,keep */
        if (!(con->flags & CON_BOOT))
                early_efi_keep = true;
        return 0;
}

struct console early_efi_console = {
        .name =         "earlyefi",
        .write =        early_efi_write,
        .setup =        early_efi_setup,
        .flags =        CON_PRINTBUFFER,
        .index =        -1,
};