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(struct device *dev, struct device_attribute *attr,
  40                             const char *buf, size_t size)
  41 {
  42         struct timed_output_dev *tdev = dev_get_drvdata(dev);
  43         int value;
  44
  45         if (sscanf(buf, "%d", &value) != 1)
  46                 return -EINVAL;
  47
  48         tdev->enable(tdev, value);
  49
  50         return size;
  51 }
  52 static DEVICE_ATTR_RW(enable);
  53
  54 static struct attribute *timed_output_attrs[] = {
  55         &dev_attr_enable.attr,
  56         NULL,
  57 };
  58 ATTRIBUTE_GROUPS(timed_output);
  59
  60 static int create_timed_output_class(void)
  61 {
  62         if (!timed_output_class) {
  63                 timed_output_class = class_create(THIS_MODULE, "timed_output");
  64                 if (IS_ERR(timed_output_class))
  65                         return PTR_ERR(timed_output_class);
  66                 atomic_set(&device_count, 0);
  67                 timed_output_class->dev_groups = timed_output_groups;
  68         }
  69
  70         return 0;
  71 }
  72
  73 int timed_output_dev_register(struct timed_output_dev *tdev)
  74 {
  75         int ret;
  76
  77         if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
  78                 return -EINVAL;
  79
  80         ret = create_timed_output_class();
  81         if (ret < 0)
  82                 return ret;
  83
  84         tdev->index = atomic_inc_return(&device_count);
  85         tdev->dev = device_create(timed_output_class, NULL,
  86                 MKDEV(0, tdev->index), NULL, "%s", tdev->name);
  87         if (IS_ERR(tdev->dev))
  88                 return PTR_ERR(tdev->dev);
  89
  90         dev_set_drvdata(tdev->dev, tdev);
  91         tdev->state = 0;
  92         return 0;
  93 }
  94 EXPORT_SYMBOL_GPL(timed_output_dev_register);
  95
  96 void timed_output_dev_unregister(struct timed_output_dev *tdev)
  97 {
  98         tdev->enable(tdev, 0);
  99         device_destroy(timed_output_class, MKDEV(0, tdev->index));
 100         dev_set_drvdata(tdev->dev, NULL);
 101 }
 102 EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
 103
 104 static int __init timed_output_init(void)
 105 {
 106         return create_timed_output_class();
 107 }
 108
 109 static void __exit timed_output_exit(void)
 110 {
 111         class_destroy(timed_output_class);
 112 }
 113
 114 module_init(timed_output_init);
 115 module_exit(timed_output_exit);
 116
 117 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 118 MODULE_DESCRIPTION("timed output class driver");
 119 MODULE_LICENSE("GPL");