drivers/leds/led-class.c

   1 /*
   2  * LED Class Core
   3  *
   4  * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
   5  * Copyright (C) 2005-2006 Richard Purdie <rpurdie@openedhand.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/list.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/device.h>
  18 #include <linux/sysdev.h>
  19 #include <linux/timer.h>
  20 #include <linux/err.h>
  21 #include <linux/ctype.h>
  22 #include <linux/leds.h>
  23 #include "leds.h"
  24
  25 static struct class *leds_class;
  26
  27 static ssize_t led_brightness_show(struct class_device *dev, char *buf)
  28 {
  29         struct led_classdev *led_cdev = class_get_devdata(dev);
  30         ssize_t ret = 0;
  31
  32         /* no lock needed for this */
  33         sprintf(buf, "%u\n", led_cdev->brightness);
  34         ret = strlen(buf) + 1;
  35
  36         return ret;
  37 }
  38
  39 static ssize_t led_brightness_store(struct class_device *dev,
  40                                 const char *buf, size_t size)
  41 {
  42         struct led_classdev *led_cdev = class_get_devdata(dev);
  43         ssize_t ret = -EINVAL;
  44         char *after;
  45         unsigned long state = simple_strtoul(buf, &after, 10);
  46         size_t count = after - buf;
  47
  48         if (*after && isspace(*after))
  49                 count++;
  50
  51         if (count == size) {
  52                 ret = count;
  53                 led_set_brightness(led_cdev, state);
  54         }
  55
  56         return ret;
  57 }
  58
  59 static CLASS_DEVICE_ATTR(brightness, 0644, led_brightness_show,
  60                         led_brightness_store);
  61 #ifdef CONFIG_LEDS_TRIGGERS
  62 static CLASS_DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  63 #endif
  64
  65 /**
  66  * led_classdev_suspend - suspend an led_classdev.
  67  * @led_cdev: the led_classdev to suspend.
  68  */
  69 void led_classdev_suspend(struct led_classdev *led_cdev)
  70 {
  71         led_cdev->flags |= LED_SUSPENDED;
  72         led_cdev->brightness_set(led_cdev, 0);
  73 }
  74 EXPORT_SYMBOL_GPL(led_classdev_suspend);
  75
  76 /**
  77  * led_classdev_resume - resume an led_classdev.
  78  * @led_cdev: the led_classdev to resume.
  79  */
  80 void led_classdev_resume(struct led_classdev *led_cdev)
  81 {
  82         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
  83         led_cdev->flags &= ~LED_SUSPENDED;
  84 }
  85 EXPORT_SYMBOL_GPL(led_classdev_resume);
  86
  87 /**
  88  * led_classdev_register - register a new object of led_classdev class.
  89  * @dev: The device to register.
  90  * @led_cdev: the led_classdev structure for this device.
  91  */
  92 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
  93 {
  94         int rc;
  95
  96         led_cdev->class_dev = class_device_create(leds_class, NULL, 0,
  97                                                 parent, "%s", led_cdev->name);
  98         if (unlikely(IS_ERR(led_cdev->class_dev)))
  99                 return PTR_ERR(led_cdev->class_dev);
 100
 101         class_set_devdata(led_cdev->class_dev, led_cdev);
 102
 103         /* register the attributes */
 104         rc = class_device_create_file(led_cdev->class_dev,
 105                                       &class_device_attr_brightness);
 106         if (rc)
 107                 goto err_out;
 108
 109         /* add to the list of leds */
 110         write_lock(&leds_list_lock);
 111         list_add_tail(&led_cdev->node, &leds_list);
 112         write_unlock(&leds_list_lock);
 113
 114 #ifdef CONFIG_LEDS_TRIGGERS
 115         rwlock_init(&led_cdev->trigger_lock);
 116
 117         rc = class_device_create_file(led_cdev->class_dev,
 118                                       &class_device_attr_trigger);
 119         if (rc)
 120                 goto err_out_led_list;
 121
 122         led_trigger_set_default(led_cdev);
 123 #endif
 124
 125         printk(KERN_INFO "Registered led device: %s\n",
 126                         led_cdev->class_dev->class_id);
 127
 128         return 0;
 129
 130 #ifdef CONFIG_LEDS_TRIGGERS
 131 err_out_led_list:
 132         class_device_remove_file(led_cdev->class_dev,
 133                                 &class_device_attr_brightness);
 134         list_del(&led_cdev->node);
 135 #endif
 136 err_out:
 137         class_device_unregister(led_cdev->class_dev);
 138         return rc;
 139 }
 140 EXPORT_SYMBOL_GPL(led_classdev_register);
 141
 142 /**
 143  * led_classdev_unregister - unregisters a object of led_properties class.
 144  * @led_cdev: the led device to unregister
 145  *
 146  * Unregisters a previously registered via led_classdev_register object.
 147  */
 148 void led_classdev_unregister(struct led_classdev *led_cdev)
 149 {
 150         class_device_remove_file(led_cdev->class_dev,
 151                                 &class_device_attr_brightness);
 152 #ifdef CONFIG_LEDS_TRIGGERS
 153         class_device_remove_file(led_cdev->class_dev,
 154                                 &class_device_attr_trigger);
 155         write_lock(&led_cdev->trigger_lock);
 156         if (led_cdev->trigger)
 157                 led_trigger_set(led_cdev, NULL);
 158         write_unlock(&led_cdev->trigger_lock);
 159 #endif
 160
 161         class_device_unregister(led_cdev->class_dev);
 162
 163         write_lock(&leds_list_lock);
 164         list_del(&led_cdev->node);
 165         write_unlock(&leds_list_lock);
 166 }
 167 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 168
 169 static int __init leds_init(void)
 170 {
 171         leds_class = class_create(THIS_MODULE, "leds");
 172         if (IS_ERR(leds_class))
 173                 return PTR_ERR(leds_class);
 174         return 0;
 175 }
 176
 177 static void __exit leds_exit(void)
 178 {
 179         class_destroy(leds_class);
 180 }
 181
 182 subsys_initcall(leds_init);
 183 module_exit(leds_exit);
 184
 185 MODULE_AUTHOR("John Lenz, Richard Purdie");
 186 MODULE_LICENSE("GPL");
 187 MODULE_DESCRIPTION("LED Class Interface");