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  */
7 
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/gpio.h>
12 #include <linux/interrupt.h>
13 #include <linux/leds.h>
14 #include <linux/slab.h>
15 #include "../leds.h"
16 
17 struct gpio_trig_data {
18 	struct led_classdev *led;
19 
20 	unsigned desired_brightness;	/* desired brightness when led is on */
21 	unsigned inverted;		/* true when gpio is inverted */
22 	unsigned gpio;			/* gpio that triggers the leds */
23 };
24 
25 static irqreturn_t gpio_trig_irq(int irq, void *_led)
26 {
27 	struct led_classdev *led = _led;
28 	struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
29 	int tmp;
30 
31 	tmp = gpio_get_value_cansleep(gpio_data->gpio);
32 	if (gpio_data->inverted)
33 		tmp = !tmp;
34 
35 	if (tmp) {
36 		if (gpio_data->desired_brightness)
37 			led_set_brightness_nosleep(gpio_data->led,
38 					   gpio_data->desired_brightness);
39 		else
40 			led_set_brightness_nosleep(gpio_data->led, LED_FULL);
41 	} else {
42 		led_set_brightness_nosleep(gpio_data->led, LED_OFF);
43 	}
44 
45 	return IRQ_HANDLED;
46 }
47 
48 static ssize_t gpio_trig_brightness_show(struct device *dev,
49 		struct device_attribute *attr, char *buf)
50 {
51 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
52 
53 	return sprintf(buf, "%u\n", gpio_data->desired_brightness);
54 }
55 
56 static ssize_t gpio_trig_brightness_store(struct device *dev,
57 		struct device_attribute *attr, const char *buf, size_t n)
58 {
59 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
60 	unsigned desired_brightness;
61 	int ret;
62 
63 	ret = sscanf(buf, "%u", &desired_brightness);
64 	if (ret < 1 || desired_brightness > 255) {
65 		dev_err(dev, "invalid value\n");
66 		return -EINVAL;
67 	}
68 
69 	gpio_data->desired_brightness = desired_brightness;
70 
71 	return n;
72 }
73 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
74 		gpio_trig_brightness_store);
75 
76 static ssize_t gpio_trig_inverted_show(struct device *dev,
77 		struct device_attribute *attr, char *buf)
78 {
79 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
80 
81 	return sprintf(buf, "%u\n", gpio_data->inverted);
82 }
83 
84 static ssize_t gpio_trig_inverted_store(struct device *dev,
85 		struct device_attribute *attr, const char *buf, size_t n)
86 {
87 	struct led_classdev *led = led_trigger_get_led(dev);
88 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
89 	unsigned long inverted;
90 	int ret;
91 
92 	ret = kstrtoul(buf, 10, &inverted);
93 	if (ret < 0)
94 		return ret;
95 
96 	if (inverted > 1)
97 		return -EINVAL;
98 
99 	gpio_data->inverted = inverted;
100 
101 	/* After inverting, we need to update the LED. */
102 	if (gpio_is_valid(gpio_data->gpio))
103 		gpio_trig_irq(0, led);
104 
105 	return n;
106 }
107 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
108 		gpio_trig_inverted_store);
109 
110 static ssize_t gpio_trig_gpio_show(struct device *dev,
111 		struct device_attribute *attr, char *buf)
112 {
113 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
114 
115 	return sprintf(buf, "%u\n", gpio_data->gpio);
116 }
117 
118 static ssize_t gpio_trig_gpio_store(struct device *dev,
119 		struct device_attribute *attr, const char *buf, size_t n)
120 {
121 	struct led_classdev *led = led_trigger_get_led(dev);
122 	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
123 	unsigned gpio;
124 	int ret;
125 
126 	ret = sscanf(buf, "%u", &gpio);
127 	if (ret < 1) {
128 		dev_err(dev, "couldn't read gpio number\n");
129 		return -EINVAL;
130 	}
131 
132 	if (gpio_data->gpio == gpio)
133 		return n;
134 
135 	if (!gpio_is_valid(gpio)) {
136 		if (gpio_is_valid(gpio_data->gpio))
137 			free_irq(gpio_to_irq(gpio_data->gpio), led);
138 		gpio_data->gpio = gpio;
139 		return n;
140 	}
141 
142 	ret = request_threaded_irq(gpio_to_irq(gpio), NULL, gpio_trig_irq,
143 			IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
144 			| IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
145 	if (ret) {
146 		dev_err(dev, "request_irq failed with error %d\n", ret);
147 	} else {
148 		if (gpio_is_valid(gpio_data->gpio))
149 			free_irq(gpio_to_irq(gpio_data->gpio), led);
150 		gpio_data->gpio = gpio;
151 		/* After changing the GPIO, we need to update the LED. */
152 		gpio_trig_irq(0, led);
153 	}
154 
155 	return ret ? ret : n;
156 }
157 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
158 
159 static struct attribute *gpio_trig_attrs[] = {
160 	&dev_attr_desired_brightness.attr,
161 	&dev_attr_inverted.attr,
162 	&dev_attr_gpio.attr,
163 	NULL
164 };
165 ATTRIBUTE_GROUPS(gpio_trig);
166 
167 static int gpio_trig_activate(struct led_classdev *led)
168 {
169 	struct gpio_trig_data *gpio_data;
170 
171 	gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
172 	if (!gpio_data)
173 		return -ENOMEM;
174 
175 	gpio_data->led = led;
176 	gpio_data->gpio = -ENOENT;
177 
178 	led_set_trigger_data(led, gpio_data);
179 
180 	return 0;
181 }
182 
183 static void gpio_trig_deactivate(struct led_classdev *led)
184 {
185 	struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
186 
187 	if (gpio_is_valid(gpio_data->gpio))
188 		free_irq(gpio_to_irq(gpio_data->gpio), led);
189 	kfree(gpio_data);
190 }
191 
192 static struct led_trigger gpio_led_trigger = {
193 	.name		= "gpio",
194 	.activate	= gpio_trig_activate,
195 	.deactivate	= gpio_trig_deactivate,
196 	.groups		= gpio_trig_groups,
197 };
198 module_led_trigger(gpio_led_trigger);
199 
200 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
201 MODULE_DESCRIPTION("GPIO LED trigger");
202 MODULE_LICENSE("GPL v2");
203