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         sscanf(buf, "%d", &value);
  45         tdev->enable(tdev, value);
  46
  47         return size;
  48 }
  49
  50 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, enable_show, enable_store);
  51
  52 static int create_timed_output_class(void)
  53 {
  54         if (!timed_output_class) {
  55                 timed_output_class = class_create(THIS_MODULE, "timed_output");
  56                 if (IS_ERR(timed_output_class))
  57                         return PTR_ERR(timed_output_class);
  58                 atomic_set(&device_count, 0);
  59         }
  60
  61         return 0;
  62 }
  63
  64 int timed_output_dev_register(struct timed_output_dev *tdev)
  65 {
  66         int ret;
  67
  68         if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
  69                 return -EINVAL;
  70
  71         ret = create_timed_output_class();
  72         if (ret < 0)
  73                 return ret;
  74
  75         tdev->index = atomic_inc_return(&device_count);
  76         tdev->dev = device_create(timed_output_class, NULL,
  77                 MKDEV(0, tdev->index), NULL, tdev->name);
  78         if (IS_ERR(tdev->dev))
  79                 return PTR_ERR(tdev->dev);
  80
  81         ret = device_create_file(tdev->dev, &dev_attr_enable);
  82         if (ret < 0)
  83                 goto err_create_file;
  84
  85         dev_set_drvdata(tdev->dev, tdev);
  86         tdev->state = 0;
  87         return 0;
  88
  89 err_create_file:
  90         device_destroy(timed_output_class, MKDEV(0, tdev->index));
  91         printk(KERN_ERR "timed_output: Failed to register driver %s\n",
  92                         tdev->name);
  93
  94         return ret;
  95 }
  96 EXPORT_SYMBOL_GPL(timed_output_dev_register);
  97
  98 void timed_output_dev_unregister(struct timed_output_dev *tdev)
  99 {
 100         device_remove_file(tdev->dev, &dev_attr_enable);
 101         device_destroy(timed_output_class, MKDEV(0, tdev->index));
 102         dev_set_drvdata(tdev->dev, NULL);
 103 }
 104 EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
 105
 106 static int __init timed_output_init(void)
 107 {
 108         return create_timed_output_class();
 109 }
 110
 111 static void __exit timed_output_exit(void)
 112 {
 113         class_destroy(timed_output_class);
 114 }
 115
 116 module_init(timed_output_init);
 117 module_exit(timed_output_exit);
 118
 119 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 120 MODULE_DESCRIPTION("timed output class driver");
 121 MODULE_LICENSE("GPL");