drivers/staging/android/timed_output.c

   1 /* drivers/misc/timed_output.c
   2  *
   3  * Copyright (C) 2009 Google, Inc.
   4  * Author: Mike Lockwood <lockwood@android.com>
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/types.h>
  19 #include <linux/device.h>
  20 #include <linux/fs.h>
  21 #include <linux/err.h>
  22
  23 #include "timed_output.h"
  24
  25 static struct class *timed_output_class;
  26 static atomic_t device_count;
  27
  28 static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
  29                 char *buf)
  30 {
  31         struct timed_output_dev *tdev = dev_get_drvdata(dev);
  32         int remaining = tdev->get_time(tdev);
  33
  34         return sprintf(buf, "%d\n", remaining);
  35 }
  36
  37 static ssize_t enable_store(
  38                 struct device *dev, struct device_attribute *attr,
  39                 const char *buf, size_t size)
  40 {
  41         struct timed_output_dev *tdev = dev_get_drvdata(dev);
  42         int value;
  43
  44         if (sscanf(buf, "%d", &value) != 1)
  45                 return -EINVAL;
  46
  47         tdev->enable(tdev, value);
  48
  49         return size;
  50 }
  51
  52 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, enable_show, enable_store);
  53
  54 static int create_timed_output_class(void)
  55 {
  56         if (!timed_output_class) {
  57                 timed_output_class = class_create(THIS_MODULE, "timed_output");
  58                 if (IS_ERR(timed_output_class))
  59                         return PTR_ERR(timed_output_class);
  60                 atomic_set(&device_count, 0);
  61         }
  62
  63         return 0;
  64 }
  65
  66 int timed_output_dev_register(struct timed_output_dev *tdev)
  67 {
  68         int ret;
  69
  70         if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
  71                 return -EINVAL;
  72
  73         ret = create_timed_output_class();
  74         if (ret < 0)
  75                 return ret;
  76
  77         tdev->index = atomic_inc_return(&device_count);
  78         tdev->dev = device_create(timed_output_class, NULL,
  79                 MKDEV(0, tdev->index), NULL, tdev->name);
  80         if (IS_ERR(tdev->dev))
  81                 return PTR_ERR(tdev->dev);
  82
  83         ret = device_create_file(tdev->dev, &dev_attr_enable);
  84         if (ret < 0)
  85                 goto err_create_file;
  86
  87         dev_set_drvdata(tdev->dev, tdev);
  88         tdev->state = 0;
  89         return 0;
  90
  91 err_create_file:
  92         device_destroy(timed_output_class, MKDEV(0, tdev->index));
  93         printk(KERN_ERR "timed_output: Failed to register driver %s\n",
  94                         tdev->name);
  95
  96         return ret;
  97 }
  98 EXPORT_SYMBOL_GPL(timed_output_dev_register);
  99
 100 void timed_output_dev_unregister(struct timed_output_dev *tdev)
 101 {
 102         device_remove_file(tdev->dev, &dev_attr_enable);
 103         device_destroy(timed_output_class, MKDEV(0, tdev->index));
 104         dev_set_drvdata(tdev->dev, NULL);
 105 }
 106 EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
 107
 108 static int __init timed_output_init(void)
 109 {
 110         return create_timed_output_class();
 111 }
 112
 113 static void __exit timed_output_exit(void)
 114 {
 115         class_destroy(timed_output_class);
 116 }
 117
 118 module_init(timed_output_init);
 119 module_exit(timed_output_exit);
 120
 121 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 122 MODULE_DESCRIPTION("timed output class driver");
 123 MODULE_LICENSE("GPL");