// SPDX-License-Identifier: GPL-2.0-only
/*
 * Datasheet:
 * https://www.kinet-ic.com/uploads/web/KTD2801/KTD2801-04b.pdf
 */
#include <linux/backlight.h>
#include <linux/gpio/consumer.h>
#include <linux/leds-expresswire.h>
#include <linux/platform_device.h>
#include <linux/property.h>

#define KTD2801_DEFAULT_BRIGHTNESS      100
#define KTD2801_MAX_BRIGHTNESS          255

/* These values have been extracted from Samsung's driver. */
static const struct expresswire_timing ktd2801_timing = {
        .poweroff_us = 2600,
        .detect_delay_us = 150,
        .detect_us = 270,
        .data_start_us = 5,
        .short_bitset_us = 5,
        .long_bitset_us = 15,
        .end_of_data_low_us = 10,
        .end_of_data_high_us = 350
};

struct ktd2801_backlight {
        struct expresswire_common_props props;
        struct backlight_device *bd;
        bool was_on;
};

static int ktd2801_update_status(struct backlight_device *bd)
{
        struct ktd2801_backlight *ktd2801 = bl_get_data(bd);
        u8 brightness = (u8) backlight_get_brightness(bd);

        if (backlight_is_blank(bd)) {
                expresswire_power_off(&ktd2801->props);
                ktd2801->was_on = false;
                return 0;
        }

        if (!ktd2801->was_on) {
                expresswire_enable(&ktd2801->props);
                ktd2801->was_on = true;
        }

        expresswire_write_u8(&ktd2801->props, brightness);

        return 0;
}

static const struct backlight_ops ktd2801_backlight_ops = {
        .options = BL_CORE_SUSPENDRESUME,
        .update_status = ktd2801_update_status,
};

static int ktd2801_backlight_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct backlight_device *bd;
        struct ktd2801_backlight *ktd2801;
        u32 brightness, max_brightness;
        int ret;

        ktd2801 = devm_kzalloc(dev, sizeof(*ktd2801), GFP_KERNEL);
        if (!ktd2801)
                return -ENOMEM;
        ktd2801->was_on = true;
        ktd2801->props.timing = ktd2801_timing;

        ret = device_property_read_u32(dev, "max-brightness", &max_brightness);
        if (ret)
                max_brightness = KTD2801_MAX_BRIGHTNESS;
        if (max_brightness > KTD2801_MAX_BRIGHTNESS) {
                dev_err(dev, "illegal max brightness specified\n");
                max_brightness = KTD2801_MAX_BRIGHTNESS;
        }

        ret = device_property_read_u32(dev, "default-brightness", &brightness);
        if (ret)
                brightness = KTD2801_DEFAULT_BRIGHTNESS;
        if (brightness > max_brightness) {
                dev_err(dev, "default brightness exceeds max\n");
                brightness = max_brightness;
        }

        ktd2801->props.ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);
        if (IS_ERR(ktd2801->props.ctrl_gpio))
                return dev_err_probe(dev, PTR_ERR(ktd2801->props.ctrl_gpio),
                                "failed to get backlight GPIO");
        gpiod_set_consumer_name(ktd2801->props.ctrl_gpio, dev_name(dev));

        bd = devm_backlight_device_register(dev, dev_name(dev), dev, ktd2801,
                        &ktd2801_backlight_ops, NULL);
        if (IS_ERR(bd))
                return dev_err_probe(dev, PTR_ERR(bd),
                                "failed to register backlight");

        bd->props.max_brightness = max_brightness;
        bd->props.brightness = brightness;

        ktd2801->bd = bd;
        platform_set_drvdata(pdev, bd);
        backlight_update_status(bd);

        return 0;
}

static const struct of_device_id ktd2801_of_match[] = {
        { .compatible = "kinetic,ktd2801" },
        { }
};
MODULE_DEVICE_TABLE(of, ktd2801_of_match);

static struct platform_driver ktd2801_backlight_driver = {
        .driver = {
                .name = "ktd2801-backlight",
                .of_match_table = ktd2801_of_match,
        },
        .probe = ktd2801_backlight_probe,
};
module_platform_driver(ktd2801_backlight_driver);

MODULE_IMPORT_NS("EXPRESSWIRE");
MODULE_AUTHOR("Duje Mihanović <duje.mihanovic@skole.hr>");
MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver");
MODULE_LICENSE("GPL");