1 // SPDX-License-Identifier: GPL-2.0-only
3 * ledtrig-gio.c - LED Trigger Based on GPIO events
5 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
6 * Copyright 2023 Linus Walleij <linus.walleij@linaro.org>
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>
18 struct 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 */
24 static irqreturn_t gpio_trig_irq(int irq, void *_led)
26 struct led_classdev *led = _led;
27 struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
30 tmp = gpiod_get_value_cansleep(gpio_data->gpiod);
32 if (gpio_data->desired_brightness)
33 led_set_brightness_nosleep(gpio_data->led,
34 gpio_data->desired_brightness);
36 led_set_brightness_nosleep(gpio_data->led, LED_FULL);
38 led_set_brightness_nosleep(gpio_data->led, LED_OFF);
44 static ssize_t gpio_trig_brightness_show(struct device *dev,
45 struct device_attribute *attr, char *buf)
47 struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
49 return sprintf(buf, "%u\n", gpio_data->desired_brightness);
52 static ssize_t gpio_trig_brightness_store(struct device *dev,
53 struct device_attribute *attr, const char *buf, size_t n)
55 struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
56 unsigned desired_brightness;
59 ret = sscanf(buf, "%u", &desired_brightness);
60 if (ret < 1 || desired_brightness > 255) {
61 dev_err(dev, "invalid value\n");
65 gpio_data->desired_brightness = desired_brightness;
69 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
70 gpio_trig_brightness_store);
72 static struct attribute *gpio_trig_attrs[] = {
73 &dev_attr_desired_brightness.attr,
76 ATTRIBUTE_GROUPS(gpio_trig);
78 static int gpio_trig_activate(struct led_classdev *led)
80 struct gpio_trig_data *gpio_data;
81 struct device *dev = led->dev;
84 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
89 * The generic property "trigger-sources" is followed,
90 * and we hope that this is a GPIO.
92 gpio_data->gpiod = fwnode_gpiod_get_index(dev->fwnode,
96 if (IS_ERR(gpio_data->gpiod)) {
97 ret = PTR_ERR(gpio_data->gpiod);
101 if (!gpio_data->gpiod) {
102 dev_err(dev, "no valid GPIO for the trigger\n");
107 gpio_data->led = led;
108 led_set_trigger_data(led, gpio_data);
110 ret = request_threaded_irq(gpiod_to_irq(gpio_data->gpiod), NULL, gpio_trig_irq,
111 IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
112 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
114 dev_err(dev, "request_irq failed with error %d\n", ret);
115 gpiod_put(gpio_data->gpiod);
120 /* Finally update the LED to initial status */
121 gpio_trig_irq(0, led);
126 static void gpio_trig_deactivate(struct led_classdev *led)
128 struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
130 free_irq(gpiod_to_irq(gpio_data->gpiod), led);
131 gpiod_put(gpio_data->gpiod);
135 static struct led_trigger gpio_led_trigger = {
137 .activate = gpio_trig_activate,
138 .deactivate = gpio_trig_deactivate,
139 .groups = gpio_trig_groups,
141 module_led_trigger(gpio_led_trigger);
143 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
144 MODULE_DESCRIPTION("GPIO LED trigger");
145 MODULE_LICENSE("GPL v2");