// SPDX-License-Identifier: GPL-2.0-only
/*
 * ledtrig-gio.c - LED Trigger Based on GPIO events
 *
 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
 * Copyright 2023 Linus Walleij <linus.walleij@linaro.org>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include "../leds.h"

struct gpio_trig_data {
        struct led_classdev *led;
        unsigned desired_brightness;    /* desired brightness when led is on */
        struct gpio_desc *gpiod;        /* gpio that triggers the led */
};

static irqreturn_t gpio_trig_irq(int irq, void *_led)
{
        struct led_classdev *led = _led;
        struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
        int tmp;

        tmp = gpiod_get_value_cansleep(gpio_data->gpiod);
        if (tmp) {
                if (gpio_data->desired_brightness)
                        led_set_brightness_nosleep(gpio_data->led,
                                           gpio_data->desired_brightness);
                else
                        led_set_brightness_nosleep(gpio_data->led, LED_FULL);
        } else {
                led_set_brightness_nosleep(gpio_data->led, LED_OFF);
        }

        return IRQ_HANDLED;
}

static ssize_t desired_brightness_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);

        return sysfs_emit(buf, "%u\n", gpio_data->desired_brightness);
}

static ssize_t desired_brightness_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t n)
{
        struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
        u8 desired_brightness;
        int ret;

        ret = kstrtou8(buf, 10, &desired_brightness);
        if (ret)
                return ret;

        gpio_data->desired_brightness = desired_brightness;

        return n;
}
static DEVICE_ATTR_RW(desired_brightness);

static struct attribute *gpio_trig_attrs[] = {
        &dev_attr_desired_brightness.attr,
        NULL
};
ATTRIBUTE_GROUPS(gpio_trig);

static int gpio_trig_activate(struct led_classdev *led)
{
        struct gpio_trig_data *gpio_data;
        struct device *dev = led->dev;
        int ret;

        gpio_data = kzalloc_obj(*gpio_data);
        if (!gpio_data)
                return -ENOMEM;

        /*
         * The generic property "trigger-sources" is followed,
         * and we hope that this is a GPIO.
         */
        gpio_data->gpiod = gpiod_get_optional(dev, "trigger-sources", GPIOD_IN);
        if (IS_ERR(gpio_data->gpiod)) {
                ret = PTR_ERR(gpio_data->gpiod);
                kfree(gpio_data);
                return ret;
        }
        if (!gpio_data->gpiod) {
                dev_err(dev, "no valid GPIO for the trigger\n");
                kfree(gpio_data);
                return -EINVAL;
        }

        gpiod_set_consumer_name(gpio_data->gpiod, "led-trigger");

        gpio_data->led = led;
        led_set_trigger_data(led, gpio_data);

        ret = request_threaded_irq(gpiod_to_irq(gpio_data->gpiod), NULL, gpio_trig_irq,
                        IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
                        | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
        if (ret) {
                dev_err(dev, "request_irq failed with error %d\n", ret);
                gpiod_put(gpio_data->gpiod);
                kfree(gpio_data);
                return ret;
        }

        /* Finally update the LED to initial status */
        gpio_trig_irq(0, led);

        return 0;
}

static void gpio_trig_deactivate(struct led_classdev *led)
{
        struct gpio_trig_data *gpio_data = led_get_trigger_data(led);

        free_irq(gpiod_to_irq(gpio_data->gpiod), led);
        gpiod_put(gpio_data->gpiod);
        kfree(gpio_data);
}

static struct led_trigger gpio_led_trigger = {
        .name           = "gpio",
        .activate       = gpio_trig_activate,
        .deactivate     = gpio_trig_deactivate,
        .groups         = gpio_trig_groups,
};
module_led_trigger(gpio_led_trigger);

MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
MODULE_DESCRIPTION("GPIO LED trigger");
MODULE_LICENSE("GPL v2");