1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ledtrig-gio.c - LED Trigger Based on GPIO events
  4 *
  5 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
  6 * Copyright 2023 Linus Walleij <linus.walleij@linaro.org>
  7 */
  8
  9#include <linux/module.h>
 10#include <linux/kernel.h>
 11#include <linux/init.h>
 12#include <linux/gpio/consumer.h>
 13#include <linux/interrupt.h>
 14#include <linux/leds.h>
 15#include <linux/slab.h>
 16#include "../leds.h"
 17
 18struct gpio_trig_data {
 19	struct led_classdev *led;
 20	unsigned desired_brightness;	/* desired brightness when led is on */
 21	struct gpio_desc *gpiod;	/* gpio that triggers the led */
 22};
 23
 24static irqreturn_t gpio_trig_irq(int irq, void *_led)
 25{
 26	struct led_classdev *led = _led;
 27	struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
 28	int tmp;
 29
 30	tmp = gpiod_get_value_cansleep(gpio_data->gpiod);
 31	if (tmp) {
 32		if (gpio_data->desired_brightness)
 33			led_set_brightness_nosleep(gpio_data->led,
 34					   gpio_data->desired_brightness);
 35		else
 36			led_set_brightness_nosleep(gpio_data->led, LED_FULL);
 37	} else {
 38		led_set_brightness_nosleep(gpio_data->led, LED_OFF);
 39	}
 40
 41	return IRQ_HANDLED;
 42}
 43
 44static ssize_t desired_brightness_show(struct device *dev,
 45		struct device_attribute *attr, char *buf)
 46{
 47	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
 48
 49	return sysfs_emit(buf, "%u\n", gpio_data->desired_brightness);
 50}
 51
 52static ssize_t desired_brightness_store(struct device *dev,
 53		struct device_attribute *attr, const char *buf, size_t n)
 54{
 55	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
 56	u8 desired_brightness;
 57	int ret;
 58
 59	ret = kstrtou8(buf, 10, &desired_brightness);
 60	if (ret)
 61		return ret;
 62
 63	gpio_data->desired_brightness = desired_brightness;
 64
 65	return n;
 66}
 67static DEVICE_ATTR_RW(desired_brightness);
 68
 69static struct attribute *gpio_trig_attrs[] = {
 70	&dev_attr_desired_brightness.attr,
 71	NULL
 72};
 73ATTRIBUTE_GROUPS(gpio_trig);
 74
 75static int gpio_trig_activate(struct led_classdev *led)
 76{
 77	struct gpio_trig_data *gpio_data;
 78	struct device *dev = led->dev;
 79	int ret;
 80
 81	gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
 82	if (!gpio_data)
 83		return -ENOMEM;
 84
 85	/*
 86	 * The generic property "trigger-sources" is followed,
 87	 * and we hope that this is a GPIO.
 88	 */
 89	gpio_data->gpiod = gpiod_get_optional(dev, "trigger-sources", GPIOD_IN);
 90	if (IS_ERR(gpio_data->gpiod)) {
 91		ret = PTR_ERR(gpio_data->gpiod);
 92		kfree(gpio_data);
 93		return ret;
 94	}
 95	if (!gpio_data->gpiod) {
 96		dev_err(dev, "no valid GPIO for the trigger\n");
 97		kfree(gpio_data);
 98		return -EINVAL;
 99	}
100
101	gpiod_set_consumer_name(gpio_data->gpiod, "led-trigger");
102
103	gpio_data->led = led;
104	led_set_trigger_data(led, gpio_data);
105
106	ret = request_threaded_irq(gpiod_to_irq(gpio_data->gpiod), NULL, gpio_trig_irq,
107			IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
108			| IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
109	if (ret) {
110		dev_err(dev, "request_irq failed with error %d\n", ret);
111		gpiod_put(gpio_data->gpiod);
112		kfree(gpio_data);
113		return ret;
114	}
115
116	/* Finally update the LED to initial status */
117	gpio_trig_irq(0, led);
118
119	return 0;
120}
121
122static void gpio_trig_deactivate(struct led_classdev *led)
123{
124	struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
125
126	free_irq(gpiod_to_irq(gpio_data->gpiod), led);
127	gpiod_put(gpio_data->gpiod);
128	kfree(gpio_data);
129}
130
131static struct led_trigger gpio_led_trigger = {
132	.name		= "gpio",
133	.activate	= gpio_trig_activate,
134	.deactivate	= gpio_trig_deactivate,
135	.groups		= gpio_trig_groups,
136};
137module_led_trigger(gpio_led_trigger);
138
139MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
140MODULE_DESCRIPTION("GPIO LED trigger");
141MODULE_LICENSE("GPL v2");