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_cdev: led);
28 int tmp;
29
30 tmp = gpiod_get_value_cansleep(desc: gpio_data->gpiod);
31 if (tmp) {
32 if (gpio_data->desired_brightness)
33 led_set_brightness_nosleep(led_cdev: gpio_data->led,
34 value: gpio_data->desired_brightness);
35 else
36 led_set_brightness_nosleep(led_cdev: gpio_data->led, value: LED_FULL);
37 } else {
38 led_set_brightness_nosleep(led_cdev: gpio_data->led, value: 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, fmt: "%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(s: buf, base: 10, res: &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(size: 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, con_id: "trigger-sources", flags: GPIOD_IN);
90 if (IS_ERR(ptr: gpio_data->gpiod)) {
91 ret = PTR_ERR(ptr: gpio_data->gpiod);
92 kfree(objp: gpio_data);
93 return ret;
94 }
95 if (!gpio_data->gpiod) {
96 dev_err(dev, "no valid GPIO for the trigger\n");
97 kfree(objp: gpio_data);
98 return -EINVAL;
99 }
100
101 gpiod_set_consumer_name(desc: gpio_data->gpiod, name: "led-trigger");
102
103 gpio_data->led = led;
104 led_set_trigger_data(led_cdev: led, trigger_data: gpio_data);
105
106 ret = request_threaded_irq(irq: gpiod_to_irq(desc: gpio_data->gpiod), NULL, thread_fn: gpio_trig_irq,
107 IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
108 | IRQF_TRIGGER_FALLING, name: "ledtrig-gpio", dev: led);
109 if (ret) {
110 dev_err(dev, "request_irq failed with error %d\n", ret);
111 gpiod_put(desc: gpio_data->gpiod);
112 kfree(objp: gpio_data);
113 return ret;
114 }
115
116 /* Finally update the LED to initial status */
117 gpio_trig_irq(irq: 0, led: 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_cdev: led);
125
126 free_irq(gpiod_to_irq(desc: gpio_data->gpiod), led);
127 gpiod_put(desc: gpio_data->gpiod);
128 kfree(objp: 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");
142

source code of linux/drivers/leds/trigger/ledtrig-gpio.c