/*
 * Simplest possible simple frame-buffer driver, as a platform device
 *
 * Copyright (c) 2013, Stephen Warren
 *
 * Based on q40fb.c, which was:
 * Copyright (C) 2001 Richard Zidlicky <rz@linux-m68k.org>
 *
 * Also based on offb.c, which was:
 * Copyright (C) 1997 Geert Uytterhoeven
 * Copyright (C) 1996 Paul Mackerras
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/errno.h>
#include <linux/fb.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>

static struct fb_fix_screeninfo simplefb_fix = {
        .id             = "simple",
        .type           = FB_TYPE_PACKED_PIXELS,
        .visual         = FB_VISUAL_TRUECOLOR,
        .accel          = FB_ACCEL_NONE,
};

static struct fb_var_screeninfo simplefb_var = {
        .height         = -1,
        .width          = -1,
        .activate       = FB_ACTIVATE_NOW,
        .vmode          = FB_VMODE_NONINTERLACED,
};

static int simplefb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
                              u_int transp, struct fb_info *info)
{
        u32 *pal = info->pseudo_palette;
        u32 cr = red >> (16 - info->var.red.length);
        u32 cg = green >> (16 - info->var.green.length);
        u32 cb = blue >> (16 - info->var.blue.length);
        u32 value;

        if (regno >= 16)
                return -EINVAL;

        value = (cr << info->var.red.offset) |
                (cg << info->var.green.offset) |
                (cb << info->var.blue.offset);
        if (info->var.transp.length > 0) {
                u32 mask = (1 << info->var.transp.length) - 1;
                mask <<= info->var.transp.offset;
                value |= mask;
        }
        pal[regno] = value;

        return 0;
}

static struct fb_ops simplefb_ops = {
        .owner          = THIS_MODULE,
        .fb_setcolreg   = simplefb_setcolreg,
        .fb_fillrect    = cfb_fillrect,
        .fb_copyarea    = cfb_copyarea,
        .fb_imageblit   = cfb_imageblit,
};

static struct simplefb_format simplefb_formats[] = SIMPLEFB_FORMATS;

struct simplefb_params {
        u32 width;
        u32 height;
        u32 stride;
        struct simplefb_format *format;
};

static int simplefb_parse_dt(struct platform_device *pdev,
                           struct simplefb_params *params)
{
        struct device_node *np = pdev->dev.of_node;
        int ret;
        const char *format;
        int i;

        ret = of_property_read_u32(np, "width", &params->width);
        if (ret) {
                dev_err(&pdev->dev, "Can't parse width property\n");
                return ret;
        }

        ret = of_property_read_u32(np, "height", &params->height);
        if (ret) {
                dev_err(&pdev->dev, "Can't parse height property\n");
                return ret;
        }

        ret = of_property_read_u32(np, "stride", &params->stride);
        if (ret) {
                dev_err(&pdev->dev, "Can't parse stride property\n");
                return ret;
        }

        ret = of_property_read_string(np, "format", &format);
        if (ret) {
                dev_err(&pdev->dev, "Can't parse format property\n");
                return ret;
        }
        params->format = NULL;
        for (i = 0; i < ARRAY_SIZE(simplefb_formats); i++) {
                if (strcmp(format, simplefb_formats[i].name))
                        continue;
                params->format = &simplefb_formats[i];
                break;
        }
        if (!params->format) {
                dev_err(&pdev->dev, "Invalid format value\n");
                return -EINVAL;
        }

        return 0;
}

static int simplefb_parse_pd(struct platform_device *pdev,
                             struct simplefb_params *params)
{
        struct simplefb_platform_data *pd = pdev->dev.platform_data;
        int i;

        params->width = pd->width;
        params->height = pd->height;
        params->stride = pd->stride;

        params->format = NULL;
        for (i = 0; i < ARRAY_SIZE(simplefb_formats); i++) {
                if (strcmp(pd->format, simplefb_formats[i].name))
                        continue;

                params->format = &simplefb_formats[i];
                break;
        }

        if (!params->format) {
                dev_err(&pdev->dev, "Invalid format value\n");
                return -EINVAL;
        }

        return 0;
}

static int simplefb_probe(struct platform_device *pdev)
{
        int ret;
        struct simplefb_params params;
        struct fb_info *info;
        struct resource *mem;

        if (fb_get_options("simplefb", NULL))
                return -ENODEV;

        ret = -ENODEV;
        if (pdev->dev.platform_data)
                ret = simplefb_parse_pd(pdev, &params);
        else if (pdev->dev.of_node)
                ret = simplefb_parse_dt(pdev, &params);

        if (ret)
                return ret;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!mem) {
                dev_err(&pdev->dev, "No memory resource\n");
                return -EINVAL;
        }

        info = framebuffer_alloc(sizeof(u32) * 16, &pdev->dev);
        if (!info)
                return -ENOMEM;
        platform_set_drvdata(pdev, info);

        info->fix = simplefb_fix;
        info->fix.smem_start = mem->start;
        info->fix.smem_len = resource_size(mem);
        info->fix.line_length = params.stride;

        info->var = simplefb_var;
        info->var.xres = params.width;
        info->var.yres = params.height;
        info->var.xres_virtual = params.width;
        info->var.yres_virtual = params.height;
        info->var.bits_per_pixel = params.format->bits_per_pixel;
        info->var.red = params.format->red;
        info->var.green = params.format->green;
        info->var.blue = params.format->blue;
        info->var.transp = params.format->transp;

        info->apertures = alloc_apertures(1);
        if (!info->apertures) {
                framebuffer_release(info);
                return -ENOMEM;
        }
        info->apertures->ranges[0].base = info->fix.smem_start;
        info->apertures->ranges[0].size = info->fix.smem_len;

        info->fbops = &simplefb_ops;
        info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
        info->screen_base = devm_ioremap(&pdev->dev, info->fix.smem_start,
                                         info->fix.smem_len);
        if (!info->screen_base) {
                framebuffer_release(info);
                return -ENODEV;
        }
        info->pseudo_palette = (void *)(info + 1);

        ret = register_framebuffer(info);
        if (ret < 0) {
                dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret);
                framebuffer_release(info);
                return ret;
        }

        dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);

        return 0;
}

static int simplefb_remove(struct platform_device *pdev)
{
        struct fb_info *info = platform_get_drvdata(pdev);

        unregister_framebuffer(info);
        framebuffer_release(info);

        return 0;
}

static const struct of_device_id simplefb_of_match[] = {
        { .compatible = "simple-framebuffer", },
        { },
};
MODULE_DEVICE_TABLE(of, simplefb_of_match);

static struct platform_driver simplefb_driver = {
        .driver = {
                .name = "simple-framebuffer",
                .owner = THIS_MODULE,
                .of_match_table = simplefb_of_match,
        },
        .probe = simplefb_probe,
        .remove = simplefb_remove,
};
module_platform_driver(simplefb_driver);

MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
MODULE_DESCRIPTION("Simple framebuffer driver");
MODULE_LICENSE("GPL v2");