drivers/leds/ledtrig-gpio.c

   1 /*
   2  * ledtrig-gio.c - LED Trigger Based on GPIO events
   3  *
   4  * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/gpio.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/workqueue.h>
  18 #include <linux/leds.h>
  19 #include "leds.h"
  20
  21 struct gpio_trig_data {
  22         struct led_classdev *led;
  23         struct work_struct work;
  24
  25         unsigned desired_brightness;    /* desired brightness when led is on */
  26         unsigned inverted;              /* true when gpio is inverted */
  27         unsigned gpio;                  /* gpio that triggers the leds */
  28 };
  29
  30 static irqreturn_t gpio_trig_irq(int irq, void *_led)
  31 {
  32         struct led_classdev *led = _led;
  33         struct gpio_trig_data *gpio_data = led->trigger_data;
  34
  35         /* just schedule_work since gpio_get_value can sleep */
  36         schedule_work(&gpio_data->work);
  37
  38         return IRQ_HANDLED;
  39 };
  40
  41 static void gpio_trig_work(struct work_struct *work)
  42 {
  43         struct gpio_trig_data *gpio_data = container_of(work,
  44                         struct gpio_trig_data, work);
  45         int tmp;
  46
  47        if (!gpio_data->gpio)
  48                return;
  49
  50        tmp = gpio_get_value(gpio_data->gpio);
  51        if (gpio_data->inverted)
  52                tmp = !tmp;
  53
  54        if (tmp) {
  55                if (gpio_data->desired_brightness)
  56                        led_set_brightness(gpio_data->led,
  57                                        gpio_data->desired_brightness);
  58                else
  59                        led_set_brightness(gpio_data->led, LED_FULL);
  60        } else {
  61                led_set_brightness(gpio_data->led, LED_OFF);
  62        }
  63 }
  64
  65 static ssize_t gpio_trig_brightness_show(struct device *dev,
  66                 struct device_attribute *attr, char *buf)
  67 {
  68         struct led_classdev *led = dev_get_drvdata(dev);
  69         struct gpio_trig_data *gpio_data = led->trigger_data;
  70
  71         return sprintf(buf, "%u\n", gpio_data->desired_brightness);
  72 }
  73
  74 static ssize_t gpio_trig_brightness_store(struct device *dev,
  75                 struct device_attribute *attr, const char *buf, size_t n)
  76 {
  77         struct led_classdev *led = dev_get_drvdata(dev);
  78         struct gpio_trig_data *gpio_data = led->trigger_data;
  79         unsigned desired_brightness;
  80         int ret;
  81
  82         ret = sscanf(buf, "%u", &desired_brightness);
  83         if (ret < 1 || desired_brightness > 255) {
  84                 dev_err(dev, "invalid value\n");
  85                 return -EINVAL;
  86         }
  87
  88         gpio_data->desired_brightness = desired_brightness;
  89
  90         return n;
  91 }
  92 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
  93                 gpio_trig_brightness_store);
  94
  95 static ssize_t gpio_trig_inverted_show(struct device *dev,
  96                 struct device_attribute *attr, char *buf)
  97 {
  98         struct led_classdev *led = dev_get_drvdata(dev);
  99         struct gpio_trig_data *gpio_data = led->trigger_data;
 100
 101         return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no");
 102 }
 103
 104 static ssize_t gpio_trig_inverted_store(struct device *dev,
 105                 struct device_attribute *attr, const char *buf, size_t n)
 106 {
 107         struct led_classdev *led = dev_get_drvdata(dev);
 108         struct gpio_trig_data *gpio_data = led->trigger_data;
 109         unsigned inverted;
 110         int ret;
 111
 112         ret = sscanf(buf, "%u", &inverted);
 113         if (ret < 1) {
 114                 dev_err(dev, "invalid value\n");
 115                 return -EINVAL;
 116         }
 117
 118         gpio_data->inverted = !!inverted;
 119
 120         return n;
 121 }
 122 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
 123                 gpio_trig_inverted_store);
 124
 125 static ssize_t gpio_trig_gpio_show(struct device *dev,
 126                 struct device_attribute *attr, char *buf)
 127 {
 128         struct led_classdev *led = dev_get_drvdata(dev);
 129         struct gpio_trig_data *gpio_data = led->trigger_data;
 130
 131         return sprintf(buf, "%u\n", gpio_data->gpio);
 132 }
 133
 134 static ssize_t gpio_trig_gpio_store(struct device *dev,
 135                 struct device_attribute *attr, const char *buf, size_t n)
 136 {
 137         struct led_classdev *led = dev_get_drvdata(dev);
 138         struct gpio_trig_data *gpio_data = led->trigger_data;
 139         unsigned gpio;
 140         int ret;
 141
 142         ret = sscanf(buf, "%u", &gpio);
 143         if (ret < 1) {
 144                 dev_err(dev, "couldn't read gpio number\n");
 145                 flush_work(&gpio_data->work);
 146                 return -EINVAL;
 147         }
 148
 149         if (!gpio) {
 150                 free_irq(gpio_to_irq(gpio_data->gpio), led);
 151                 return n;
 152         }
 153
 154         if (gpio_data->gpio > 0 && gpio_data->gpio != gpio)
 155                 free_irq(gpio_to_irq(gpio_data->gpio), led);
 156
 157         gpio_data->gpio = gpio;
 158         ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
 159                         IRQF_SHARED | IRQF_TRIGGER_RISING
 160                         | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
 161         if (ret)
 162                 dev_err(dev, "request_irq failed with error %d\n", ret);
 163
 164         return ret ? ret : n;
 165 }
 166 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
 167
 168 static void gpio_trig_activate(struct led_classdev *led)
 169 {
 170         struct gpio_trig_data *gpio_data;
 171         int ret;
 172
 173         gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
 174         if (!gpio_data)
 175                 return;
 176
 177         ret = device_create_file(led->dev, &dev_attr_gpio);
 178         if (ret)
 179                 goto err_gpio;
 180
 181         ret = device_create_file(led->dev, &dev_attr_inverted);
 182         if (ret)
 183                 goto err_inverted;
 184
 185         ret = device_create_file(led->dev, &dev_attr_desired_brightness);
 186         if (ret)
 187                 goto err_brightness;
 188
 189         gpio_data->led = led;
 190         led->trigger_data = gpio_data;
 191         INIT_WORK(&gpio_data->work, gpio_trig_work);
 192
 193         return;
 194
 195 err_brightness:
 196         device_remove_file(led->dev, &dev_attr_inverted);
 197
 198 err_inverted:
 199         device_remove_file(led->dev, &dev_attr_gpio);
 200
 201 err_gpio:
 202         kfree(gpio_data);
 203 }
 204
 205 static void gpio_trig_deactivate(struct led_classdev *led)
 206 {
 207         struct gpio_trig_data *gpio_data = led->trigger_data;
 208
 209         if (gpio_data) {
 210                 device_remove_file(led->dev, &dev_attr_gpio);
 211                 device_remove_file(led->dev, &dev_attr_inverted);
 212                 device_remove_file(led->dev, &dev_attr_desired_brightness);
 213                 flush_work(&gpio_data->work);
 214                 free_irq(gpio_to_irq(gpio_data->gpio),led);
 215                 kfree(gpio_data);
 216         }
 217 }
 218
 219 static struct led_trigger gpio_led_trigger = {
 220         .name           = "gpio",
 221         .activate       = gpio_trig_activate,
 222         .deactivate     = gpio_trig_deactivate,
 223 };
 224
 225 static int __init gpio_trig_init(void)
 226 {
 227         return led_trigger_register(&gpio_led_trigger);
 228 }
 229 module_init(gpio_trig_init);
 230
 231 static void __exit gpio_trig_exit(void)
 232 {
 233         led_trigger_unregister(&gpio_led_trigger);
 234 }
 235 module_exit(gpio_trig_exit);
 236
 237 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
 238 MODULE_DESCRIPTION("GPIO LED trigger");
 239 MODULE_LICENSE("GPL");