// SPDX-License-Identifier: GPL-2.0-only
/*
 * gpio_backlight.c - Simple GPIO-controlled backlight
 */

#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/gpio_backlight.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>

struct gpio_backlight {
        struct device *dev;
        struct gpio_desc *gpiod;
};

static int gpio_backlight_update_status(struct backlight_device *bl)
{
        struct gpio_backlight *gbl = bl_get_data(bl);

        gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));

        return 0;
}

static bool gpio_backlight_controls_device(struct backlight_device *bl,
                                           struct device *display_dev)
{
        struct gpio_backlight *gbl = bl_get_data(bl);

        return !gbl->dev || gbl->dev == display_dev;
}

static const struct backlight_ops gpio_backlight_ops = {
        .options         = BL_CORE_SUSPENDRESUME,
        .update_status   = gpio_backlight_update_status,
        .controls_device = gpio_backlight_controls_device,
};

static int gpio_backlight_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
        struct device_node *of_node = dev->of_node;
        struct backlight_properties props;
        struct backlight_device *bl;
        struct gpio_backlight *gbl;
        int ret, init_brightness, def_value;

        gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
        if (gbl == NULL)
                return -ENOMEM;

        if (pdata)
                gbl->dev = pdata->dev;

        def_value = device_property_read_bool(dev, "default-on");

        gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
        if (IS_ERR(gbl->gpiod))
                return dev_err_probe(dev, PTR_ERR(gbl->gpiod),
                                     "The gpios parameter is missing or invalid\n");

        memset(&props, 0, sizeof(props));
        props.type = BACKLIGHT_RAW;
        props.max_brightness = 1;
        bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
                                            &gpio_backlight_ops, &props);
        if (IS_ERR(bl)) {
                dev_err(dev, "failed to register backlight\n");
                return PTR_ERR(bl);
        }

        /* Set the initial power state */
        if (!of_node || !of_node->phandle)
                /* Not booted with device tree or no phandle link to the node */
                bl->props.power = def_value ? BACKLIGHT_POWER_ON
                                            : BACKLIGHT_POWER_OFF;
        else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
                bl->props.power = BACKLIGHT_POWER_OFF;
        else
                bl->props.power = BACKLIGHT_POWER_ON;

        bl->props.brightness = 1;

        init_brightness = backlight_get_brightness(bl);
        ret = gpiod_direction_output(gbl->gpiod, init_brightness);
        if (ret) {
                dev_err(dev, "failed to set initial brightness\n");
                return ret;
        }

        platform_set_drvdata(pdev, bl);
        return 0;
}

static struct of_device_id gpio_backlight_of_match[] = {
        { .compatible = "gpio-backlight" },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);

static struct platform_driver gpio_backlight_driver = {
        .driver         = {
                .name           = "gpio-backlight",
                .of_match_table = gpio_backlight_of_match,
        },
        .probe          = gpio_backlight_probe,
};

module_platform_driver(gpio_backlight_driver);

MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
MODULE_DESCRIPTION("GPIO-based Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-backlight");