// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2013 Intel Corporation; author Matt Fleming
 */

#include <linux/console.h>
#include <linux/efi.h>
#include <linux/font.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/serial_core.h>
#include <linux/screen_info.h>

#include <asm/early_ioremap.h>

static const struct console *earlycon_console __initdata;
static const struct font_desc *font;
static u32 efi_x, efi_y;
static u64 fb_base;
static bool fb_wb;
static void *efi_fb;

/*
 * EFI earlycon needs to use early_memremap() to map the framebuffer.
 * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
 * memremap() should be used instead. memremap() 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 int __init efi_earlycon_remap_fb(void)
{
        /* bail if there is no bootconsole or it has been disabled already */
        if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
                return 0;

        efi_fb = memremap(fb_base, screen_info.lfb_size,
                          fb_wb ? MEMREMAP_WB : MEMREMAP_WC);

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

static int __init efi_earlycon_unmap_fb(void)
{
        /* unmap the bootconsole fb unless keep_bootcon has left it enabled */
        if (efi_fb && !(earlycon_console->flags & CON_ENABLED))
                memunmap(efi_fb);
        return 0;
}
late_initcall(efi_earlycon_unmap_fb);

static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
{
        pgprot_t fb_prot;

        if (efi_fb)
                return efi_fb + start;

        fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
        return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
}

static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
{
        if (efi_fb)
                return;

        early_memunmap(addr, len);
}

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

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

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

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

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

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

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

                memmove(dst, src, len);

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

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

        bytes = BITS_TO_BYTES(font->width);
        src = font->data + c * font->height * bytes + h * bytes;

        for (m = 0; m < font->width; m++) {
                n = m % 8;
                x = *(src + m / 8);
                if ((x >> (7 - n)) & 1)
                        *dst = color_white;
                else
                        *dst = color_black;
                dst++;
        }
}

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

        si = &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 = efi_earlycon_map((efi_y + h) * len, len);
                        if (!dst)
                                return;

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

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

                        efi_earlycon_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 + font->width > si->lfb_width) {
                        efi_x = 0;
                        efi_y += font->height;
                }

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

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

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

static int __init efi_earlycon_setup(struct earlycon_device *device,
                                     const char *opt)
{
        struct screen_info *si;
        u16 xres, yres;
        u32 i;

        if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
                return -ENODEV;

        fb_base = screen_info.lfb_base;
        if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
                fb_base |= (u64)screen_info.ext_lfb_base << 32;

        fb_wb = opt && !strcmp(opt, "ram");

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

        /*
         * efi_earlycon_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++)
                efi_earlycon_scroll_up();

        device->con->write = efi_earlycon_write;
        earlycon_console = device->con;
        return 0;
}
EARLYCON_DECLARE(efifb, efi_earlycon_setup);