// SPDX-License-Identifier: GPL-2.0-only

#include <dt-bindings/leds/rt4831-backlight.h>
#include <linux/backlight.h>
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>

#define RT4831_REG_BLCFG        0x02
#define RT4831_REG_BLDIML       0x04
#define RT4831_REG_ENABLE       0x08
#define RT4831_REG_BLOPT2       0x11

#define RT4831_BLMAX_BRIGHTNESS 2048

#define RT4831_BLOVP_MASK       GENMASK(7, 5)
#define RT4831_BLOVP_SHIFT      5
#define RT4831_BLPWMEN_MASK     BIT(0)
#define RT4831_BLEN_MASK        BIT(4)
#define RT4831_BLCH_MASK        GENMASK(3, 0)
#define RT4831_BLDIML_MASK      GENMASK(2, 0)
#define RT4831_BLDIMH_MASK      GENMASK(10, 3)
#define RT4831_BLDIMH_SHIFT     3
#define RT4831_BLOCP_MASK       GENMASK(1, 0)

#define RT4831_BLOCP_MINUA      900000
#define RT4831_BLOCP_MAXUA      1800000
#define RT4831_BLOCP_STEPUA     300000

struct rt4831_priv {
        struct device *dev;
        struct regmap *regmap;
        struct backlight_device *bl;
};

static int rt4831_bl_update_status(struct backlight_device *bl_dev)
{
        struct rt4831_priv *priv = bl_get_data(bl_dev);
        int brightness = backlight_get_brightness(bl_dev);
        unsigned int enable = brightness ? RT4831_BLEN_MASK : 0;
        u8 v[2];
        int ret;

        if (brightness) {
                v[0] = (brightness - 1) & RT4831_BLDIML_MASK;
                v[1] = ((brightness - 1) & RT4831_BLDIMH_MASK) >> RT4831_BLDIMH_SHIFT;

                ret = regmap_raw_write(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
                if (ret)
                        return ret;
        }

        return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLEN_MASK, enable);

}

static int rt4831_bl_get_brightness(struct backlight_device *bl_dev)
{
        struct rt4831_priv *priv = bl_get_data(bl_dev);
        unsigned int val;
        u8 v[2];
        int ret;

        ret = regmap_read(priv->regmap, RT4831_REG_ENABLE, &val);
        if (ret)
                return ret;

        if (!(val & RT4831_BLEN_MASK))
                return 0;

        ret = regmap_raw_read(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
        if (ret)
                return ret;

        ret = (v[1] << RT4831_BLDIMH_SHIFT) + (v[0] & RT4831_BLDIML_MASK) + 1;

        return ret;
}

static const struct backlight_ops rt4831_bl_ops = {
        .options = BL_CORE_SUSPENDRESUME,
        .update_status = rt4831_bl_update_status,
        .get_brightness = rt4831_bl_get_brightness,
};

static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
                                             struct backlight_properties *bl_props)
{
        struct device *dev = priv->dev;
        u8 propval;
        u32 brightness, ocp_uA;
        unsigned int val = 0;
        int ret;

        /* common properties */
        ret = device_property_read_u32(dev, "max-brightness", &brightness);
        if (ret)
                brightness = RT4831_BLMAX_BRIGHTNESS;

        bl_props->max_brightness = min_t(u32, brightness, RT4831_BLMAX_BRIGHTNESS);

        ret = device_property_read_u32(dev, "default-brightness", &brightness);
        if (ret)
                brightness = bl_props->max_brightness;

        bl_props->brightness = min_t(u32, brightness, bl_props->max_brightness);

        /* vendor properties */
        if (device_property_read_bool(dev, "richtek,pwm-enable"))
                val = RT4831_BLPWMEN_MASK;

        ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLPWMEN_MASK, val);
        if (ret)
                return ret;

        ret = device_property_read_u8(dev, "richtek,bled-ovp-sel", &propval);
        if (ret)
                propval = RT4831_BLOVPLVL_21V;

        propval = min_t(u8, propval, RT4831_BLOVPLVL_29V);
        ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLOVP_MASK,
                                 propval << RT4831_BLOVP_SHIFT);
        if (ret)
                return ret;

        /*
         * This OCP level is used to protect and limit the inductor current.
         * If inductor peak current reach the level, low-side MOSFET will be
         * turned off. Meanwhile, the output channel current may be limited.
         * To match the configured channel current, the inductor chosen must
         * be higher than the OCP level.
         *
         * Not like the OVP level, the default 21V can be used in the most
         * application. But if the chosen OCP level is smaller than needed,
         * it will also affect the backlight channel output current to be
         * smaller than the register setting.
         */
        ret = device_property_read_u32(dev, "richtek,bled-ocp-microamp",
                                       &ocp_uA);
        if (!ret) {
                ocp_uA = clamp_val(ocp_uA, RT4831_BLOCP_MINUA,
                                   RT4831_BLOCP_MAXUA);
                val = DIV_ROUND_UP(ocp_uA - RT4831_BLOCP_MINUA,
                                   RT4831_BLOCP_STEPUA);
                ret = regmap_update_bits(priv->regmap, RT4831_REG_BLOPT2,
                                         RT4831_BLOCP_MASK, val);
                if (ret)
                        return ret;
        }

        ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
        if (ret) {
                dev_err(dev, "richtek,channel-use DT property missing\n");
                return ret;
        }

        if (!(propval & RT4831_BLCH_MASK)) {
                dev_err(dev, "No channel specified\n");
                return -EINVAL;
        }

        return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLCH_MASK, propval);
}

static int rt4831_bl_probe(struct platform_device *pdev)
{
        struct rt4831_priv *priv;
        struct backlight_properties bl_props = { .type = BACKLIGHT_RAW,
                                                 .scale = BACKLIGHT_SCALE_LINEAR };
        int ret;

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

        priv->dev = &pdev->dev;

        priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!priv->regmap) {
                dev_err(&pdev->dev, "Failed to init regmap\n");
                return -ENODEV;
        }

        ret = rt4831_parse_backlight_properties(priv, &bl_props);
        if (ret) {
                dev_err(&pdev->dev, "Failed to parse backlight properties\n");
                return ret;
        }

        priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, priv,
                                                  &rt4831_bl_ops, &bl_props);
        if (IS_ERR(priv->bl)) {
                dev_err(&pdev->dev, "Failed to register backlight\n");
                return PTR_ERR(priv->bl);
        }

        backlight_update_status(priv->bl);
        platform_set_drvdata(pdev, priv);

        return 0;
}

static void rt4831_bl_remove(struct platform_device *pdev)
{
        struct rt4831_priv *priv = platform_get_drvdata(pdev);
        struct backlight_device *bl_dev = priv->bl;

        bl_dev->props.brightness = 0;
        backlight_update_status(priv->bl);
}

static const struct of_device_id __maybe_unused rt4831_bl_of_match[] = {
        { .compatible = "richtek,rt4831-backlight", },
        {}
};
MODULE_DEVICE_TABLE(of, rt4831_bl_of_match);

static struct platform_driver rt4831_bl_driver = {
        .driver = {
                .name = "rt4831-backlight",
                .of_match_table = rt4831_bl_of_match,
        },
        .probe = rt4831_bl_probe,
        .remove = rt4831_bl_remove,
};
module_platform_driver(rt4831_bl_driver);

MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
MODULE_DESCRIPTION("Richtek RT4831 Backlight Driver");
MODULE_LICENSE("GPL v2");