// SPDX-License-Identifier: GPL-2.0
/*
 * Procedures for drawing on the screen early on in the boot process.
 *
 * Benjamin Herrenschmidt <benh@kernel.crashing.org>
 */
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/font.h>

#include <asm/btext.h>
#include <asm/oplib.h>
#include <asm/io.h>

#define NO_SCROLL

#ifndef NO_SCROLL
static void scrollscreen(void);
#endif

static void draw_byte(unsigned char c, long locX, long locY);
static void draw_byte_32(const unsigned char *bits, unsigned int *base, int rb);
static void draw_byte_16(const unsigned char *bits, unsigned int *base, int rb);
static void draw_byte_8(const unsigned char *bits, unsigned int *base, int rb);

#define __force_data __section(".data")

static int g_loc_X __force_data;
static int g_loc_Y __force_data;
static int g_max_loc_X __force_data;
static int g_max_loc_Y __force_data;

static int dispDeviceRowBytes __force_data;
static int dispDeviceDepth  __force_data;
static int dispDeviceRect[4] __force_data;
static unsigned char *dispDeviceBase __force_data;

static int __init btext_initialize(phandle node)
{
        unsigned int width, height, depth, pitch;
        unsigned long address = 0;
        u32 prop;

        if (prom_getproperty(node, "width", (char *)&width, 4) < 0)
                return -EINVAL;
        if (prom_getproperty(node, "height", (char *)&height, 4) < 0)
                return -EINVAL;
        if (prom_getproperty(node, "depth", (char *)&depth, 4) < 0)
                return -EINVAL;
        pitch = width * ((depth + 7) / 8);

        if (prom_getproperty(node, "linebytes", (char *)&prop, 4) >= 0 &&
            prop != 0xffffffffu)
                pitch = prop;

        if (pitch == 1)
                pitch = 0x1000;

        if (prom_getproperty(node, "address", (char *)&prop, 4) >= 0)
                address = prop;

        /* FIXME: Add support for PCI reg properties. Right now, only
         * reliable on macs
         */
        if (address == 0)
                return -EINVAL;

        g_loc_X = 0;
        g_loc_Y = 0;
        g_max_loc_X = width / 8;
        g_max_loc_Y = height / 16;
        dispDeviceBase = (unsigned char *)address;
        dispDeviceRowBytes = pitch;
        dispDeviceDepth = depth == 15 ? 16 : depth;
        dispDeviceRect[0] = dispDeviceRect[1] = 0;
        dispDeviceRect[2] = width;
        dispDeviceRect[3] = height;

        return 0;
}

/* Calc the base address of a given point (x,y) */
static unsigned char * calc_base(int x, int y)
{
        unsigned char *base = dispDeviceBase;

        base += (x + dispDeviceRect[0]) * (dispDeviceDepth >> 3);
        base += (y + dispDeviceRect[1]) * dispDeviceRowBytes;
        return base;
}

static void btext_clearscreen(void)
{
        unsigned int *base      = (unsigned int *)calc_base(0, 0);
        unsigned long width     = ((dispDeviceRect[2] - dispDeviceRect[0]) *
                                        (dispDeviceDepth >> 3)) >> 2;
        int i,j;

        for (i=0; i<(dispDeviceRect[3] - dispDeviceRect[1]); i++)
        {
                unsigned int *ptr = base;
                for(j=width; j; --j)
                        *(ptr++) = 0;
                base += (dispDeviceRowBytes >> 2);
        }
}

#ifndef NO_SCROLL
static void scrollscreen(void)
{
        unsigned int *src       = (unsigned int *)calc_base(0,16);
        unsigned int *dst       = (unsigned int *)calc_base(0,0);
        unsigned long width     = ((dispDeviceRect[2] - dispDeviceRect[0]) *
                                   (dispDeviceDepth >> 3)) >> 2;
        int i,j;

        for (i=0; i<(dispDeviceRect[3] - dispDeviceRect[1] - 16); i++)
        {
                unsigned int *src_ptr = src;
                unsigned int *dst_ptr = dst;
                for(j=width; j; --j)
                        *(dst_ptr++) = *(src_ptr++);
                src += (dispDeviceRowBytes >> 2);
                dst += (dispDeviceRowBytes >> 2);
        }
        for (i=0; i<16; i++)
        {
                unsigned int *dst_ptr = dst;
                for(j=width; j; --j)
                        *(dst_ptr++) = 0;
                dst += (dispDeviceRowBytes >> 2);
        }
}
#endif /* ndef NO_SCROLL */

static void btext_drawchar(char c)
{
        int cline = 0;
#ifdef NO_SCROLL
        int x;
#endif
        switch (c) {
        case '\b':
                if (g_loc_X > 0)
                        --g_loc_X;
                break;
        case '\t':
                g_loc_X = (g_loc_X & -8) + 8;
                break;
        case '\r':
                g_loc_X = 0;
                break;
        case '\n':
                g_loc_X = 0;
                g_loc_Y++;
                cline = 1;
                break;
        default:
                draw_byte(c, g_loc_X++, g_loc_Y);
        }
        if (g_loc_X >= g_max_loc_X) {
                g_loc_X = 0;
                g_loc_Y++;
                cline = 1;
        }
#ifndef NO_SCROLL
        while (g_loc_Y >= g_max_loc_Y) {
                scrollscreen();
                g_loc_Y--;
        }
#else
        /* wrap around from bottom to top of screen so we don't
           waste time scrolling each line.  -- paulus. */
        if (g_loc_Y >= g_max_loc_Y)
                g_loc_Y = 0;
        if (cline) {
                for (x = 0; x < g_max_loc_X; ++x)
                        draw_byte(' ', x, g_loc_Y);
        }
#endif
}

static void btext_drawtext(const char *c, unsigned int len)
{
        while (len--)
                btext_drawchar(*c++);
}

static void draw_byte(unsigned char c, long locX, long locY)
{
        unsigned char *base     = calc_base(locX << 3, locY << 4);
        unsigned int font_index = c * 16;
        const unsigned char *font       = font_sun_8x16.data + font_index;
        int rb                  = dispDeviceRowBytes;

        switch(dispDeviceDepth) {
        case 24:
        case 32:
                draw_byte_32(font, (unsigned int *)base, rb);
                break;
        case 15:
        case 16:
                draw_byte_16(font, (unsigned int *)base, rb);
                break;
        case 8:
                draw_byte_8(font, (unsigned int *)base, rb);
                break;
        }
}

static unsigned int expand_bits_8[16] = {
        0x00000000,
        0x000000ff,
        0x0000ff00,
        0x0000ffff,
        0x00ff0000,
        0x00ff00ff,
        0x00ffff00,
        0x00ffffff,
        0xff000000,
        0xff0000ff,
        0xff00ff00,
        0xff00ffff,
        0xffff0000,
        0xffff00ff,
        0xffffff00,
        0xffffffff
};

static unsigned int expand_bits_16[4] = {
        0x00000000,
        0x0000ffff,
        0xffff0000,
        0xffffffff
};


static void draw_byte_32(const unsigned char *font, unsigned int *base, int rb)
{
        int l, bits;
        int fg = 0xFFFFFFFFUL;
        int bg = 0x00000000UL;

        for (l = 0; l < 16; ++l)
        {
                bits = *font++;
                base[0] = (-(bits >> 7) & fg) ^ bg;
                base[1] = (-((bits >> 6) & 1) & fg) ^ bg;
                base[2] = (-((bits >> 5) & 1) & fg) ^ bg;
                base[3] = (-((bits >> 4) & 1) & fg) ^ bg;
                base[4] = (-((bits >> 3) & 1) & fg) ^ bg;
                base[5] = (-((bits >> 2) & 1) & fg) ^ bg;
                base[6] = (-((bits >> 1) & 1) & fg) ^ bg;
                base[7] = (-(bits & 1) & fg) ^ bg;
                base = (unsigned int *) ((char *)base + rb);
        }
}

static void draw_byte_16(const unsigned char *font, unsigned int *base, int rb)
{
        int l, bits;
        int fg = 0xFFFFFFFFUL;
        int bg = 0x00000000UL;
        unsigned int *eb = (int *)expand_bits_16;

        for (l = 0; l < 16; ++l)
        {
                bits = *font++;
                base[0] = (eb[bits >> 6] & fg) ^ bg;
                base[1] = (eb[(bits >> 4) & 3] & fg) ^ bg;
                base[2] = (eb[(bits >> 2) & 3] & fg) ^ bg;
                base[3] = (eb[bits & 3] & fg) ^ bg;
                base = (unsigned int *) ((char *)base + rb);
        }
}

static void draw_byte_8(const unsigned char *font, unsigned int *base, int rb)
{
        int l, bits;
        int fg = 0x0F0F0F0FUL;
        int bg = 0x00000000UL;
        unsigned int *eb = (int *)expand_bits_8;

        for (l = 0; l < 16; ++l)
        {
                bits = *font++;
                base[0] = (eb[bits >> 4] & fg) ^ bg;
                base[1] = (eb[bits & 0xf] & fg) ^ bg;
                base = (unsigned int *) ((char *)base + rb);
        }
}

static void btext_console_write(struct console *con, const char *s,
                                unsigned int n)
{
        btext_drawtext(s, n);
}

static struct console btext_console = {
        .name   = "btext",
        .write  = btext_console_write,
        .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_BOOT | CON_ANYTIME,
        .index  = 0,
};

int __init btext_find_display(void)
{
        phandle node;
        char type[32];
        int ret;

        node = prom_inst2pkg(prom_stdout);
        if (prom_getproperty(node, "device_type", type, 32) < 0)
                return -ENODEV;
        if (strcmp(type, "display"))
                return -ENODEV;

        ret = btext_initialize(node);
        if (!ret) {
                btext_clearscreen();
                register_console(&btext_console);
        }
        return ret;
}