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 <linux/slab.h>
  20 #include "leds.h"
  21
  22 struct gpio_trig_data {
  23         struct led_classdev *led;
  24         struct work_struct work;
  25
  26         unsigned desired_brightness;    /* desired brightness when led is on */
  27         unsigned inverted;              /* true when gpio is inverted */
  28         unsigned gpio;                  /* gpio that triggers the leds */
  29 };
  30
  31 static irqreturn_t gpio_trig_irq(int irq, void *_led)
  32 {
  33         struct led_classdev *led = _led;
  34         struct gpio_trig_data *gpio_data = led->trigger_data;
  35
  36         /* just schedule_work since gpio_get_value can sleep */
  37         schedule_work(&gpio_data->work);
  38
  39         return IRQ_HANDLED;
  40 };
  41
  42 static void gpio_trig_work(struct work_struct *work)
  43 {
  44         struct gpio_trig_data *gpio_data = container_of(work,
  45                         struct gpio_trig_data, work);
  46         int tmp;
  47
  48         if (!gpio_data->gpio)
  49                 return;
  50
  51         tmp = gpio_get_value(gpio_data->gpio);
  52         if (gpio_data->inverted)
  53                 tmp = !tmp;
  54
  55         if (tmp) {
  56                 if (gpio_data->desired_brightness)
  57                         led_set_brightness(gpio_data->led,
  58                                            gpio_data->desired_brightness);
  59                 else
  60                         led_set_brightness(gpio_data->led, LED_FULL);
  61         } else {
  62                 led_set_brightness(gpio_data->led, LED_OFF);
  63         }
  64 }
  65
  66 static ssize_t gpio_trig_brightness_show(struct device *dev,
  67                 struct device_attribute *attr, char *buf)
  68 {
  69         struct led_classdev *led = dev_get_drvdata(dev);
  70         struct gpio_trig_data *gpio_data = led->trigger_data;
  71
  72         return sprintf(buf, "%u\n", gpio_data->desired_brightness);
  73 }
  74
  75 static ssize_t gpio_trig_brightness_store(struct device *dev,
  76                 struct device_attribute *attr, const char *buf, size_t n)
  77 {
  78         struct led_classdev *led = dev_get_drvdata(dev);
  79         struct gpio_trig_data *gpio_data = led->trigger_data;
  80         unsigned desired_brightness;
  81         int ret;
  82
  83         ret = sscanf(buf, "%u", &desired_brightness);
  84         if (ret < 1 || desired_brightness > 255) {
  85                 dev_err(dev, "invalid value\n");
  86                 return -EINVAL;
  87         }
  88
  89         gpio_data->desired_brightness = desired_brightness;
  90
  91         return n;
  92 }
  93 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
  94                 gpio_trig_brightness_store);
  95
  96 static ssize_t gpio_trig_inverted_show(struct device *dev,
  97                 struct device_attribute *attr, char *buf)
  98 {
  99         struct led_classdev *led = dev_get_drvdata(dev);
 100         struct gpio_trig_data *gpio_data = led->trigger_data;
 101
 102         return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no");
 103 }
 104
 105 static ssize_t gpio_trig_inverted_store(struct device *dev,
 106                 struct device_attribute *attr, const char *buf, size_t n)
 107 {
 108         struct led_classdev *led = dev_get_drvdata(dev);
 109         struct gpio_trig_data *gpio_data = led->trigger_data;
 110         unsigned inverted;
 111         int ret;
 112
 113         ret = sscanf(buf, "%u", &inverted);
 114         if (ret < 1) {
 115                 dev_err(dev, "invalid value\n");
 116                 return -EINVAL;
 117         }
 118
 119         gpio_data->inverted = !!inverted;
 120
 121         /* After inverting, we need to update the LED. */
 122         schedule_work(&gpio_data->work);
 123
 124         return n;
 125 }
 126 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
 127                 gpio_trig_inverted_store);
 128
 129 static ssize_t gpio_trig_gpio_show(struct device *dev,
 130                 struct device_attribute *attr, char *buf)
 131 {
 132         struct led_classdev *led = dev_get_drvdata(dev);
 133         struct gpio_trig_data *gpio_data = led->trigger_data;
 134
 135         return sprintf(buf, "%u\n", gpio_data->gpio);
 136 }
 137
 138 static ssize_t gpio_trig_gpio_store(struct device *dev,
 139                 struct device_attribute *attr, const char *buf, size_t n)
 140 {
 141         struct led_classdev *led = dev_get_drvdata(dev);
 142         struct gpio_trig_data *gpio_data = led->trigger_data;
 143         unsigned gpio;
 144         int ret;
 145
 146         ret = sscanf(buf, "%u", &gpio);
 147         if (ret < 1) {
 148                 dev_err(dev, "couldn't read gpio number\n");
 149                 flush_work(&gpio_data->work);
 150                 return -EINVAL;
 151         }
 152
 153         if (gpio_data->gpio == gpio)
 154                 return n;
 155
 156         if (!gpio) {
 157                 if (gpio_data->gpio != 0)
 158                         free_irq(gpio_to_irq(gpio_data->gpio), led);
 159                 gpio_data->gpio = 0;
 160                 return n;
 161         }
 162
 163         ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
 164                         IRQF_SHARED | IRQF_TRIGGER_RISING
 165                         | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
 166         if (ret) {
 167                 dev_err(dev, "request_irq failed with error %d\n", ret);
 168         } else {
 169                 if (gpio_data->gpio != 0)
 170                         free_irq(gpio_to_irq(gpio_data->gpio), led);
 171                 gpio_data->gpio = gpio;
 172         }
 173
 174         return ret ? ret : n;
 175 }
 176 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
 177
 178 static void gpio_trig_activate(struct led_classdev *led)
 179 {
 180         struct gpio_trig_data *gpio_data;
 181         int ret;
 182
 183         gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
 184         if (!gpio_data)
 185                 return;
 186
 187         ret = device_create_file(led->dev, &dev_attr_gpio);
 188         if (ret)
 189                 goto err_gpio;
 190
 191         ret = device_create_file(led->dev, &dev_attr_inverted);
 192         if (ret)
 193                 goto err_inverted;
 194
 195         ret = device_create_file(led->dev, &dev_attr_desired_brightness);
 196         if (ret)
 197                 goto err_brightness;
 198
 199         gpio_data->led = led;
 200         led->trigger_data = gpio_data;
 201         INIT_WORK(&gpio_data->work, gpio_trig_work);
 202
 203         return;
 204
 205 err_brightness:
 206         device_remove_file(led->dev, &dev_attr_inverted);
 207
 208 err_inverted:
 209         device_remove_file(led->dev, &dev_attr_gpio);
 210
 211 err_gpio:
 212         kfree(gpio_data);
 213 }
 214
 215 static void gpio_trig_deactivate(struct led_classdev *led)
 216 {
 217         struct gpio_trig_data *gpio_data = led->trigger_data;
 218
 219         if (gpio_data) {
 220                 device_remove_file(led->dev, &dev_attr_gpio);
 221                 device_remove_file(led->dev, &dev_attr_inverted);
 222                 device_remove_file(led->dev, &dev_attr_desired_brightness);
 223                 flush_work(&gpio_data->work);
 224                 if (gpio_data->gpio != 0)
 225                         free_irq(gpio_to_irq(gpio_data->gpio), led);
 226                 kfree(gpio_data);
 227         }
 228 }
 229
 230 static struct led_trigger gpio_led_trigger = {
 231         .name           = "gpio",
 232         .activate       = gpio_trig_activate,
 233         .deactivate     = gpio_trig_deactivate,
 234 };
 235
 236 static int __init gpio_trig_init(void)
 237 {
 238         return led_trigger_register(&gpio_led_trigger);
 239 }
 240 module_init(gpio_trig_init);
 241
 242 static void __exit gpio_trig_exit(void)
 243 {
 244         led_trigger_unregister(&gpio_led_trigger);
 245 }
 246 module_exit(gpio_trig_exit);
 247
 248 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
 249 MODULE_DESCRIPTION("GPIO LED trigger");
 250 MODULE_LICENSE("GPL");