// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Cirrus EP93xx lcd backlight
 *
 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
 *
 * This driver controls the pulse width modulated brightness control output,
 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/backlight.h>

#define EP93XX_MAX_COUNT                255
#define EP93XX_MAX_BRIGHT               255
#define EP93XX_DEF_BRIGHT               128

struct ep93xxbl {
        void __iomem *mmio;
        int brightness;
};

static int ep93xxbl_set(struct backlight_device *bl, int brightness)
{
        struct ep93xxbl *ep93xxbl = bl_get_data(bl);

        writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);

        ep93xxbl->brightness = brightness;

        return 0;
}

static int ep93xxbl_update_status(struct backlight_device *bl)
{
        return ep93xxbl_set(bl, backlight_get_brightness(bl));
}

static int ep93xxbl_get_brightness(struct backlight_device *bl)
{
        struct ep93xxbl *ep93xxbl = bl_get_data(bl);

        return ep93xxbl->brightness;
}

static const struct backlight_ops ep93xxbl_ops = {
        .update_status  = ep93xxbl_update_status,
        .get_brightness = ep93xxbl_get_brightness,
};

static int ep93xxbl_probe(struct platform_device *dev)
{
        struct ep93xxbl *ep93xxbl;
        struct backlight_device *bl;
        struct backlight_properties props;
        struct resource *res;

        ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
        if (!ep93xxbl)
                return -ENOMEM;

        res = platform_get_resource(dev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENXIO;

        /*
         * FIXME - We don't do a request_mem_region here because we are
         * sharing the register space with the framebuffer driver (see
         * drivers/video/ep93xx-fb.c) and doing so will cause the second
         * loaded driver to return -EBUSY.
         *
         * NOTE: No locking is required; the framebuffer does not touch
         * this register.
         */
        ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
                                      resource_size(res));
        if (!ep93xxbl->mmio)
                return -ENXIO;

        memset(&props, 0, sizeof(struct backlight_properties));
        props.type = BACKLIGHT_RAW;
        props.max_brightness = EP93XX_MAX_BRIGHT;
        bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
                                        ep93xxbl, &ep93xxbl_ops, &props);
        if (IS_ERR(bl))
                return PTR_ERR(bl);

        bl->props.brightness = EP93XX_DEF_BRIGHT;

        platform_set_drvdata(dev, bl);

        ep93xxbl_update_status(bl);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int ep93xxbl_suspend(struct device *dev)
{
        struct backlight_device *bl = dev_get_drvdata(dev);

        return ep93xxbl_set(bl, 0);
}

static int ep93xxbl_resume(struct device *dev)
{
        struct backlight_device *bl = dev_get_drvdata(dev);

        backlight_update_status(bl);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);

static struct platform_driver ep93xxbl_driver = {
        .driver         = {
                .name   = "ep93xx-bl",
                .pm     = &ep93xxbl_pm_ops,
        },
        .probe          = ep93xxbl_probe,
};

module_platform_driver(ep93xxbl_driver);

MODULE_DESCRIPTION("EP93xx Backlight Driver");
MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ep93xx-bl");