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 #define pr_fmt(fmt) "timed_output: " fmt
  18
  19 #include <linux/module.h>
  20 #include <linux/types.h>
  21 #include <linux/device.h>
  22 #include <linux/fs.h>
  23 #include <linux/err.h>
  24
  25 #include "timed_output.h"
  26
  27 static struct class *timed_output_class;
  28 static atomic_t device_count;
  29
  30 static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
  31                 char *buf)
  32 {
  33         struct timed_output_dev *tdev = dev_get_drvdata(dev);
  34         int remaining = tdev->get_time(tdev);
  35
  36         return sprintf(buf, "%d\n", remaining);
  37 }
  38
  39 static ssize_t enable_store(
  40                 struct device *dev, struct device_attribute *attr,
  41                 const char *buf, size_t size)
  42 {
  43         struct timed_output_dev *tdev = dev_get_drvdata(dev);
  44         int value;
  45
  46         if (sscanf(buf, "%d", &value) != 1)
  47                 return -EINVAL;
  48
  49         tdev->enable(tdev, value);
  50
  51         return size;
  52 }
  53
  54 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, enable_show, enable_store);
  55
  56 static int create_timed_output_class(void)
  57 {
  58         if (!timed_output_class) {
  59                 timed_output_class = class_create(THIS_MODULE, "timed_output");
  60                 if (IS_ERR(timed_output_class))
  61                         return PTR_ERR(timed_output_class);
  62                 atomic_set(&device_count, 0);
  63         }
  64
  65         return 0;
  66 }
  67
  68 int timed_output_dev_register(struct timed_output_dev *tdev)
  69 {
  70         int ret;
  71
  72         if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
  73                 return -EINVAL;
  74
  75         ret = create_timed_output_class();
  76         if (ret < 0)
  77                 return ret;
  78
  79         tdev->index = atomic_inc_return(&device_count);
  80         tdev->dev = device_create(timed_output_class, NULL,
  81                 MKDEV(0, tdev->index), NULL, tdev->name);
  82         if (IS_ERR(tdev->dev))
  83                 return PTR_ERR(tdev->dev);
  84
  85         ret = device_create_file(tdev->dev, &dev_attr_enable);
  86         if (ret < 0)
  87                 goto err_create_file;
  88
  89         dev_set_drvdata(tdev->dev, tdev);
  90         tdev->state = 0;
  91         return 0;
  92
  93 err_create_file:
  94         device_destroy(timed_output_class, MKDEV(0, tdev->index));
  95         pr_err("failed to register driver %s\n",
  96                         tdev->name);
  97
  98         return ret;
  99 }
 100 EXPORT_SYMBOL_GPL(timed_output_dev_register);
 101
 102 void timed_output_dev_unregister(struct timed_output_dev *tdev)
 103 {
 104         tdev->enable(tdev, 0);
 105         device_remove_file(tdev->dev, &dev_attr_enable);
 106         device_destroy(timed_output_class, MKDEV(0, tdev->index));
 107         dev_set_drvdata(tdev->dev, NULL);
 108 }
 109 EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
 110
 111 static int __init timed_output_init(void)
 112 {
 113         return create_timed_output_class();
 114 }
 115
 116 static void __exit timed_output_exit(void)
 117 {
 118         class_destroy(timed_output_class);
 119 }
 120
 121 module_init(timed_output_init);
 122 module_exit(timed_output_exit);
 123
 124 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 125 MODULE_DESCRIPTION("timed output class driver");
 126 MODULE_LICENSE("GPL");