// SPDX-License-Identifier: GPL-2.0-only
/*
 * PWM-based multi-color LED control
 *
 * Copyright 2022 Sven Schwermer <sven.schwermer@disruptive-technologies.com>
 */

#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/led-class-multicolor.h>
#include <linux/leds.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>

struct pwm_led {
        struct pwm_device *pwm;
        struct pwm_state state;
        bool active_low;
};

struct pwm_mc_led {
        struct led_classdev_mc mc_cdev;
        struct mutex lock;
        struct pwm_led leds[];
};

static int led_pwm_mc_set(struct led_classdev *cdev,
                          enum led_brightness brightness)
{
        struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
        struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
        unsigned long long duty;
        int ret = 0;
        int i;

        led_mc_calc_color_components(mc_cdev, brightness);

        mutex_lock(&priv->lock);

        for (i = 0; i < mc_cdev->num_colors; i++) {
                duty = priv->leds[i].state.period;
                duty *= mc_cdev->subled_info[i].brightness;
                do_div(duty, cdev->max_brightness);

                if (priv->leds[i].active_low)
                        duty = priv->leds[i].state.period - duty;

                priv->leds[i].state.duty_cycle = duty;
                /*
                 * Disabling a PWM doesn't guarantee that it emits the inactive level.
                 * So keep it on. Only for suspending the PWM should be disabled because
                 * otherwise it refuses to suspend. The possible downside is that the
                 * LED might stay (or even go) on.
                 */
                priv->leds[i].state.enabled = !(cdev->flags & LED_SUSPENDED);
                ret = pwm_apply_might_sleep(priv->leds[i].pwm,
                                            &priv->leds[i].state);
                if (ret)
                        break;
        }

        mutex_unlock(&priv->lock);

        return ret;
}

static int iterate_subleds(struct device *dev, struct pwm_mc_led *priv,
                           struct fwnode_handle *mcnode)
{
        struct mc_subled *subled = priv->mc_cdev.subled_info;
        struct fwnode_handle *fwnode;
        struct pwm_led *pwmled;
        u32 color;
        int ret;

        /* iterate over the nodes inside the multi-led node */
        fwnode_for_each_child_node(mcnode, fwnode) {
                pwmled = &priv->leds[priv->mc_cdev.num_colors];
                pwmled->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
                if (IS_ERR(pwmled->pwm)) {
                        ret = dev_err_probe(dev, PTR_ERR(pwmled->pwm), "unable to request PWM\n");
                        goto release_fwnode;
                }
                pwm_init_state(pwmled->pwm, &pwmled->state);
                pwmled->active_low = fwnode_property_read_bool(fwnode, "active-low");

                ret = fwnode_property_read_u32(fwnode, "color", &color);
                if (ret) {
                        dev_err(dev, "cannot read color: %d\n", ret);
                        goto release_fwnode;
                }

                subled[priv->mc_cdev.num_colors].color_index = color;
                priv->mc_cdev.num_colors++;
        }

        return 0;

release_fwnode:
        fwnode_handle_put(fwnode);
        return ret;
}

static int led_pwm_mc_probe(struct platform_device *pdev)
{
        struct fwnode_handle *mcnode;
        struct led_init_data init_data = {};
        struct led_classdev *cdev;
        struct mc_subled *subled;
        struct pwm_mc_led *priv;
        unsigned int count;
        int ret = 0;

        mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
        if (!mcnode)
                return dev_err_probe(&pdev->dev, -ENODEV,
                                     "expected multi-led node\n");

        /* count the nodes inside the multi-led node */
        count = fwnode_get_child_node_count(mcnode);

        priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
                            GFP_KERNEL);
        if (!priv) {
                ret = -ENOMEM;
                goto release_mcnode;
        }
        mutex_init(&priv->lock);

        subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
        if (!subled) {
                ret = -ENOMEM;
                goto release_mcnode;
        }
        priv->mc_cdev.subled_info = subled;

        /* init the multicolor's LED class device */
        cdev = &priv->mc_cdev.led_cdev;
        ret = fwnode_property_read_u32(mcnode, "max-brightness",
                                 &cdev->max_brightness);
        if (ret)
                goto release_mcnode;

        cdev->flags = LED_CORE_SUSPENDRESUME;
        cdev->brightness_set_blocking = led_pwm_mc_set;

        ret = iterate_subleds(&pdev->dev, priv, mcnode);
        if (ret)
                goto release_mcnode;

        init_data.fwnode = mcnode;
        ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
                                                        &priv->mc_cdev,
                                                        &init_data);
        if (ret) {
                dev_err(&pdev->dev,
                        "failed to register multicolor PWM led for %s: %d\n",
                        cdev->name, ret);
                goto release_mcnode;
        }

        ret = led_pwm_mc_set(cdev, cdev->brightness);
        if (ret)
                return dev_err_probe(&pdev->dev, ret,
                                     "failed to set led PWM value for %s\n",
                                     cdev->name);

        platform_set_drvdata(pdev, priv);
        return 0;

release_mcnode:
        fwnode_handle_put(mcnode);
        return ret;
}

static const struct of_device_id of_pwm_leds_mc_match[] = {
        { .compatible = "pwm-leds-multicolor", },
        {}
};
MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);

static struct platform_driver led_pwm_mc_driver = {
        .probe          = led_pwm_mc_probe,
        .driver         = {
                .name   = "leds_pwm_multicolor",
                .of_match_table = of_pwm_leds_mc_match,
        },
};
module_platform_driver(led_pwm_mc_driver);

MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
MODULE_DESCRIPTION("multi-color PWM LED driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:leds-pwm-multicolor");