leds/trigger/ledtrig-gpio.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * ledtrig-gio.c - LED Trigger Based on GPIO events
0004  *
0005  * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
0006  */
0007
0008 #include <linux/module.h>
0009 #include <linux/kernel.h>
0010 #include <linux/init.h>
0011 #include <linux/gpio.h>
0012 #include <linux/interrupt.h>
0013 #include <linux/leds.h>
0014 #include <linux/slab.h>
0015 #include "../leds.h"
0016
0017 struct gpio_trig_data {
0018     struct led_classdev *led;
0019
0020     unsigned desired_brightness;    /* desired brightness when led is on */
0021     unsigned inverted;      /* true when gpio is inverted */
0022     unsigned gpio;          /* gpio that triggers the leds */
0023 };
0024
0025 static irqreturn_t gpio_trig_irq(int irq, void *_led)
0026 {
0027     struct led_classdev *led = _led;
0028     struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
0029     int tmp;
0030
0031     tmp = gpio_get_value_cansleep(gpio_data->gpio);
0032     if (gpio_data->inverted)
0033         tmp = !tmp;
0034
0035     if (tmp) {
0036         if (gpio_data->desired_brightness)
0037             led_set_brightness_nosleep(gpio_data->led,
0038                        gpio_data->desired_brightness);
0039         else
0040             led_set_brightness_nosleep(gpio_data->led, LED_FULL);
0041     } else {
0042         led_set_brightness_nosleep(gpio_data->led, LED_OFF);
0043     }
0044
0045     return IRQ_HANDLED;
0046 }
0047
0048 static ssize_t gpio_trig_brightness_show(struct device *dev,
0049         struct device_attribute *attr, char *buf)
0050 {
0051     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0052
0053     return sprintf(buf, "%u\n", gpio_data->desired_brightness);
0054 }
0055
0056 static ssize_t gpio_trig_brightness_store(struct device *dev,
0057         struct device_attribute *attr, const char *buf, size_t n)
0058 {
0059     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0060     unsigned desired_brightness;
0061     int ret;
0062
0063     ret = sscanf(buf, "%u", &desired_brightness);
0064     if (ret < 1 || desired_brightness > 255) {
0065         dev_err(dev, "invalid value\n");
0066         return -EINVAL;
0067     }
0068
0069     gpio_data->desired_brightness = desired_brightness;
0070
0071     return n;
0072 }
0073 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
0074         gpio_trig_brightness_store);
0075
0076 static ssize_t gpio_trig_inverted_show(struct device *dev,
0077         struct device_attribute *attr, char *buf)
0078 {
0079     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0080
0081     return sprintf(buf, "%u\n", gpio_data->inverted);
0082 }
0083
0084 static ssize_t gpio_trig_inverted_store(struct device *dev,
0085         struct device_attribute *attr, const char *buf, size_t n)
0086 {
0087     struct led_classdev *led = led_trigger_get_led(dev);
0088     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0089     unsigned long inverted;
0090     int ret;
0091
0092     ret = kstrtoul(buf, 10, &inverted);
0093     if (ret < 0)
0094         return ret;
0095
0096     if (inverted > 1)
0097         return -EINVAL;
0098
0099     gpio_data->inverted = inverted;
0100
0101     /* After inverting, we need to update the LED. */
0102     if (gpio_is_valid(gpio_data->gpio))
0103         gpio_trig_irq(0, led);
0104
0105     return n;
0106 }
0107 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
0108         gpio_trig_inverted_store);
0109
0110 static ssize_t gpio_trig_gpio_show(struct device *dev,
0111         struct device_attribute *attr, char *buf)
0112 {
0113     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0114
0115     return sprintf(buf, "%u\n", gpio_data->gpio);
0116 }
0117
0118 static ssize_t gpio_trig_gpio_store(struct device *dev,
0119         struct device_attribute *attr, const char *buf, size_t n)
0120 {
0121     struct led_classdev *led = led_trigger_get_led(dev);
0122     struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
0123     unsigned gpio;
0124     int ret;
0125
0126     ret = sscanf(buf, "%u", &gpio);
0127     if (ret < 1) {
0128         dev_err(dev, "couldn't read gpio number\n");
0129         return -EINVAL;
0130     }
0131
0132     if (gpio_data->gpio == gpio)
0133         return n;
0134
0135     if (!gpio_is_valid(gpio)) {
0136         if (gpio_is_valid(gpio_data->gpio))
0137             free_irq(gpio_to_irq(gpio_data->gpio), led);
0138         gpio_data->gpio = gpio;
0139         return n;
0140     }
0141
0142     ret = request_threaded_irq(gpio_to_irq(gpio), NULL, gpio_trig_irq,
0143             IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
0144             | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
0145     if (ret) {
0146         dev_err(dev, "request_irq failed with error %d\n", ret);
0147     } else {
0148         if (gpio_is_valid(gpio_data->gpio))
0149             free_irq(gpio_to_irq(gpio_data->gpio), led);
0150         gpio_data->gpio = gpio;
0151         /* After changing the GPIO, we need to update the LED. */
0152         gpio_trig_irq(0, led);
0153     }
0154
0155     return ret ? ret : n;
0156 }
0157 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
0158
0159 static struct attribute *gpio_trig_attrs[] = {
0160     &dev_attr_desired_brightness.attr,
0161     &dev_attr_inverted.attr,
0162     &dev_attr_gpio.attr,
0163     NULL
0164 };
0165 ATTRIBUTE_GROUPS(gpio_trig);
0166
0167 static int gpio_trig_activate(struct led_classdev *led)
0168 {
0169     struct gpio_trig_data *gpio_data;
0170
0171     gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
0172     if (!gpio_data)
0173         return -ENOMEM;
0174
0175     gpio_data->led = led;
0176     gpio_data->gpio = -ENOENT;
0177
0178     led_set_trigger_data(led, gpio_data);
0179
0180     return 0;
0181 }
0182
0183 static void gpio_trig_deactivate(struct led_classdev *led)
0184 {
0185     struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
0186
0187     if (gpio_is_valid(gpio_data->gpio))
0188         free_irq(gpio_to_irq(gpio_data->gpio), led);
0189     kfree(gpio_data);
0190 }
0191
0192 static struct led_trigger gpio_led_trigger = {
0193     .name       = "gpio",
0194     .activate   = gpio_trig_activate,
0195     .deactivate = gpio_trig_deactivate,
0196     .groups     = gpio_trig_groups,
0197 };
0198 module_led_trigger(gpio_led_trigger);
0199
0200 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
0201 MODULE_DESCRIPTION("GPIO LED trigger");
0202 MODULE_LICENSE("GPL v2");