/*
 * 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>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/parser.h>
#include <linux/regulator/consumer.h>

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

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

#define PSEUDO_PALETTE_SIZE 16

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 >= PSEUDO_PALETTE_SIZE)
                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;
}

struct simplefb_par;
static void simplefb_clocks_destroy(struct simplefb_par *par);
static void simplefb_regulators_destroy(struct simplefb_par *par);

static void simplefb_destroy(struct fb_info *info)
{
        simplefb_regulators_destroy(info->par);
        simplefb_clocks_destroy(info->par);
        if (info->screen_base)
                iounmap(info->screen_base);
}

static struct fb_ops simplefb_ops = {
        .owner          = THIS_MODULE,
        .fb_destroy     = simplefb_destroy,
        .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 = dev_get_platdata(&pdev->dev);
        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;
}

struct simplefb_par {
        u32 palette[PSEUDO_PALETTE_SIZE];
#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
        bool clks_enabled;
        unsigned int clk_count;
        struct clk **clks;
#endif
#if defined CONFIG_OF && defined CONFIG_REGULATOR
        bool regulators_enabled;
        u32 regulator_count;
        struct regulator **regulators;
#endif
};

#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
/*
 * Clock handling code.
 *
 * Here we handle the clocks property of our "simple-framebuffer" dt node.
 * This is necessary so that we can make sure that any clocks needed by
 * the display engine that the bootloader set up for us (and for which it
 * provided a simplefb dt node), stay up, for the life of the simplefb
 * driver.
 *
 * When the driver unloads, we cleanly disable, and then release the clocks.
 *
 * We only complain about errors here, no action is taken as the most likely
 * error can only happen due to a mismatch between the bootloader which set
 * up simplefb, and the clock definitions in the device tree. Chances are
 * that there are no adverse effects, and if there are, a clean teardown of
 * the fb probe will not help us much either. So just complain and carry on,
 * and hope that the user actually gets a working fb at the end of things.
 */
static int simplefb_clocks_get(struct simplefb_par *par,
                               struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct clk *clock;
        int i;

        if (dev_get_platdata(&pdev->dev) || !np)
                return 0;

        par->clk_count = of_clk_get_parent_count(np);
        if (!par->clk_count)
                return 0;

        par->clks = kcalloc(par->clk_count, sizeof(struct clk *), GFP_KERNEL);
        if (!par->clks)
                return -ENOMEM;

        for (i = 0; i < par->clk_count; i++) {
                clock = of_clk_get(np, i);
                if (IS_ERR(clock)) {
                        if (PTR_ERR(clock) == -EPROBE_DEFER) {
                                while (--i >= 0) {
                                        if (par->clks[i])
                                                clk_put(par->clks[i]);
                                }
                                kfree(par->clks);
                                return -EPROBE_DEFER;
                        }
                        dev_err(&pdev->dev, "%s: clock %d not found: %ld\n",
                                __func__, i, PTR_ERR(clock));
                        continue;
                }
                par->clks[i] = clock;
        }

        return 0;
}

static void simplefb_clocks_enable(struct simplefb_par *par,
                                   struct platform_device *pdev)
{
        int i, ret;

        for (i = 0; i < par->clk_count; i++) {
                if (par->clks[i]) {
                        ret = clk_prepare_enable(par->clks[i]);
                        if (ret) {
                                dev_err(&pdev->dev,
                                        "%s: failed to enable clock %d: %d\n",
                                        __func__, i, ret);
                                clk_put(par->clks[i]);
                                par->clks[i] = NULL;
                        }
                }
        }
        par->clks_enabled = true;
}

static void simplefb_clocks_destroy(struct simplefb_par *par)
{
        int i;

        if (!par->clks)
                return;

        for (i = 0; i < par->clk_count; i++) {
                if (par->clks[i]) {
                        if (par->clks_enabled)
                                clk_disable_unprepare(par->clks[i]);
                        clk_put(par->clks[i]);
                }
        }

        kfree(par->clks);
}
#else
static int simplefb_clocks_get(struct simplefb_par *par,
        struct platform_device *pdev) { return 0; }
static void simplefb_clocks_enable(struct simplefb_par *par,
        struct platform_device *pdev) { }
static void simplefb_clocks_destroy(struct simplefb_par *par) { }
#endif

#if defined CONFIG_OF && defined CONFIG_REGULATOR

#define SUPPLY_SUFFIX "-supply"

/*
 * Regulator handling code.
 *
 * Here we handle the num-supplies and vin*-supply properties of our
 * "simple-framebuffer" dt node. This is necessary so that we can make sure
 * that any regulators needed by the display hardware that the bootloader
 * set up for us (and for which it provided a simplefb dt node), stay up,
 * for the life of the simplefb driver.
 *
 * When the driver unloads, we cleanly disable, and then release the
 * regulators.
 *
 * We only complain about errors here, no action is taken as the most likely
 * error can only happen due to a mismatch between the bootloader which set
 * up simplefb, and the regulator definitions in the device tree. Chances are
 * that there are no adverse effects, and if there are, a clean teardown of
 * the fb probe will not help us much either. So just complain and carry on,
 * and hope that the user actually gets a working fb at the end of things.
 */
static int simplefb_regulators_get(struct simplefb_par *par,
                                   struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct property *prop;
        struct regulator *regulator;
        const char *p;
        int count = 0, i = 0;

        if (dev_get_platdata(&pdev->dev) || !np)
                return 0;

        /* Count the number of regulator supplies */
        for_each_property_of_node(np, prop) {
                p = strstr(prop->name, SUPPLY_SUFFIX);
                if (p && p != prop->name)
                        count++;
        }

        if (!count)
                return 0;

        par->regulators = devm_kcalloc(&pdev->dev, count,
                                       sizeof(struct regulator *), GFP_KERNEL);
        if (!par->regulators)
                return -ENOMEM;

        /* Get all the regulators */
        for_each_property_of_node(np, prop) {
                char name[32]; /* 32 is max size of property name */

                p = strstr(prop->name, SUPPLY_SUFFIX);
                if (!p || p == prop->name)
                        continue;

                strlcpy(name, prop->name,
                        strlen(prop->name) - strlen(SUPPLY_SUFFIX) + 1);
                regulator = devm_regulator_get_optional(&pdev->dev, name);
                if (IS_ERR(regulator)) {
                        if (PTR_ERR(regulator) == -EPROBE_DEFER)
                                return -EPROBE_DEFER;
                        dev_err(&pdev->dev, "regulator %s not found: %ld\n",
                                name, PTR_ERR(regulator));
                        continue;
                }
                par->regulators[i++] = regulator;
        }
        par->regulator_count = i;

        return 0;
}

static void simplefb_regulators_enable(struct simplefb_par *par,
                                       struct platform_device *pdev)
{
        int i, ret;

        /* Enable all the regulators */
        for (i = 0; i < par->regulator_count; i++) {
                ret = regulator_enable(par->regulators[i]);
                if (ret) {
                        dev_err(&pdev->dev,
                                "failed to enable regulator %d: %d\n",
                                i, ret);
                        devm_regulator_put(par->regulators[i]);
                        par->regulators[i] = NULL;
                }
        }
        par->regulators_enabled = true;
}

static void simplefb_regulators_destroy(struct simplefb_par *par)
{
        int i;

        if (!par->regulators || !par->regulators_enabled)
                return;

        for (i = 0; i < par->regulator_count; i++)
                if (par->regulators[i])
                        regulator_disable(par->regulators[i]);
}
#else
static int simplefb_regulators_get(struct simplefb_par *par,
        struct platform_device *pdev) { return 0; }
static void simplefb_regulators_enable(struct simplefb_par *par,
        struct platform_device *pdev) { }
static void simplefb_regulators_destroy(struct simplefb_par *par) { }
#endif

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

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

        ret = -ENODEV;
        if (dev_get_platdata(&pdev->dev))
                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(struct simplefb_par), &pdev->dev);
        if (!info)
                return -ENOMEM;
        platform_set_drvdata(pdev, info);

        par = info->par;

        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) {
                ret = -ENOMEM;
                goto error_fb_release;
        }
        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 = ioremap_wc(info->fix.smem_start,
                                       info->fix.smem_len);
        if (!info->screen_base) {
                ret = -ENOMEM;
                goto error_fb_release;
        }
        info->pseudo_palette = par->palette;

        ret = simplefb_clocks_get(par, pdev);
        if (ret < 0)
                goto error_unmap;

        ret = simplefb_regulators_get(par, pdev);
        if (ret < 0)
                goto error_clocks;

        simplefb_clocks_enable(par, pdev);
        simplefb_regulators_enable(par, pdev);

        dev_info(&pdev->dev, "framebuffer at 0x%lx, 0x%x bytes, mapped to 0x%p\n",
                             info->fix.smem_start, info->fix.smem_len,
                             info->screen_base);
        dev_info(&pdev->dev, "format=%s, mode=%dx%dx%d, linelength=%d\n",
                             params.format->name,
                             info->var.xres, info->var.yres,
                             info->var.bits_per_pixel, info->fix.line_length);

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

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

        return 0;

error_regulators:
        simplefb_regulators_destroy(par);
error_clocks:
        simplefb_clocks_destroy(par);
error_unmap:
        iounmap(info->screen_base);
error_fb_release:
        framebuffer_release(info);
        return ret;
}

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",
                .of_match_table = simplefb_of_match,
        },
        .probe = simplefb_probe,
        .remove = simplefb_remove,
};

static int __init simplefb_init(void)
{
        int ret;
        struct device_node *np;

        ret = platform_driver_register(&simplefb_driver);
        if (ret)
                return ret;

        if (IS_ENABLED(CONFIG_OF_ADDRESS) && of_chosen) {
                for_each_child_of_node(of_chosen, np) {
                        if (of_device_is_compatible(np, "simple-framebuffer"))
                                of_platform_device_create(np, NULL, NULL);
                }
        }

        return 0;
}

fs_initcall(simplefb_init);

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