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
 17struct 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
 25static 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
 48static 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
 56static 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}
 73static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
 74		gpio_trig_brightness_store);
 75
 76static 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
 84static 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}
107static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
108		gpio_trig_inverted_store);
109
110static 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
118static 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}
157static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
158
159static struct attribute *gpio_trig_attrs[] = {
160	&dev_attr_desired_brightness.attr,
161	&dev_attr_inverted.attr,
162	&dev_attr_gpio.attr,
163	NULL
164};
165ATTRIBUTE_GROUPS(gpio_trig);
166
167static 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
183static 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
192static 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};
198module_led_trigger(gpio_led_trigger);
199
200MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
201MODULE_DESCRIPTION("GPIO LED trigger");
202MODULE_LICENSE("GPL v2");