drivers/input/input-polldev.c

   1 /*
   2  * Generic implementation of a polled input device
   3
   4  * Copyright (c) 2007 Dmitry Torokhov
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  */
  10
  11 #include <linux/jiffies.h>
  12 #include <linux/mutex.h>
  13 #include <linux/input-polldev.h>
  14
  15 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  16 MODULE_DESCRIPTION("Generic implementation of a polled input device");
  17 MODULE_LICENSE("GPL v2");
  18 MODULE_VERSION("0.1");
  19
  20 static DEFINE_MUTEX(polldev_mutex);
  21 static int polldev_users;
  22 static struct workqueue_struct *polldev_wq;
  23
  24 static int input_polldev_start_workqueue(void)
  25 {
  26         int retval;
  27
  28         retval = mutex_lock_interruptible(&polldev_mutex);
  29         if (retval)
  30                 return retval;
  31
  32         if (!polldev_users) {
  33                 polldev_wq = create_singlethread_workqueue("ipolldevd");
  34                 if (!polldev_wq) {
  35                         printk(KERN_ERR "input-polldev: failed to create "
  36                                 "ipolldevd workqueue\n");
  37                         retval = -ENOMEM;
  38                         goto out;
  39                 }
  40         }
  41
  42         polldev_users++;
  43
  44  out:
  45         mutex_unlock(&polldev_mutex);
  46         return retval;
  47 }
  48
  49 static void input_polldev_stop_workqueue(void)
  50 {
  51         mutex_lock(&polldev_mutex);
  52
  53         if (!--polldev_users)
  54                 destroy_workqueue(polldev_wq);
  55
  56         mutex_unlock(&polldev_mutex);
  57 }
  58
  59 static void input_polled_device_work(struct work_struct *work)
  60 {
  61         struct input_polled_dev *dev =
  62                 container_of(work, struct input_polled_dev, work.work);
  63
  64         dev->poll(dev);
  65         queue_delayed_work(polldev_wq, &dev->work,
  66                            msecs_to_jiffies(dev->poll_interval));
  67 }
  68
  69 static int input_open_polled_device(struct input_dev *input)
  70 {
  71         struct input_polled_dev *dev = input->private;
  72         int error;
  73         unsigned long ticks;
  74
  75         error = input_polldev_start_workqueue();
  76         if (error)
  77                 return error;
  78
  79         if (dev->flush)
  80                 dev->flush(dev);
  81
  82         ticks = msecs_to_jiffies(dev->poll_interval);
  83         if (ticks >= HZ)
  84                 ticks = round_jiffies(ticks);
  85         queue_delayed_work(polldev_wq, &dev->work, ticks);
  86
  87         return 0;
  88 }
  89
  90 static void input_close_polled_device(struct input_dev *input)
  91 {
  92         struct input_polled_dev *dev = input->private;
  93
  94         cancel_rearming_delayed_workqueue(polldev_wq, &dev->work);
  95         input_polldev_stop_workqueue();
  96 }
  97
  98 /**
  99  * input_allocate_polled_device - allocated memory polled device
 100  *
 101  * The function allocates memory for a polled device and also
 102  * for an input device associated with this polled device.
 103  */
 104 struct input_polled_dev *input_allocate_polled_device(void)
 105 {
 106         struct input_polled_dev *dev;
 107
 108         dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
 109         if (!dev)
 110                 return NULL;
 111
 112         dev->input = input_allocate_device();
 113         if (!dev->input) {
 114                 kfree(dev);
 115                 return NULL;
 116         }
 117
 118         return dev;
 119 }
 120 EXPORT_SYMBOL(input_allocate_polled_device);
 121
 122 /**
 123  * input_free_polled_device - free memory allocated for polled device
 124  * @dev: device to free
 125  *
 126  * The function frees memory allocated for polling device and drops
 127  * reference to the associated input device (if present).
 128  */
 129 void input_free_polled_device(struct input_polled_dev *dev)
 130 {
 131         if (dev) {
 132                 input_free_device(dev->input);
 133                 kfree(dev);
 134         }
 135 }
 136 EXPORT_SYMBOL(input_free_polled_device);
 137
 138 /**
 139  * input_register_polled_device - register polled device
 140  * @dev: device to register
 141  *
 142  * The function registers previously initialized polled input device
 143  * with input layer. The device should be allocated with call to
 144  * input_allocate_polled_device(). Callers should also set up poll()
 145  * method and set up capabilities (id, name, phys, bits) of the
 146  * corresponing input_dev structure.
 147  */
 148 int input_register_polled_device(struct input_polled_dev *dev)
 149 {
 150         struct input_dev *input = dev->input;
 151
 152         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 153         if (!dev->poll_interval)
 154                 dev->poll_interval = 500;
 155         input->private = dev;
 156         input->open = input_open_polled_device;
 157         input->close = input_close_polled_device;
 158
 159         return input_register_device(input);
 160 }
 161 EXPORT_SYMBOL(input_register_polled_device);
 162
 163 /**
 164  * input_unregister_polled_device - unregister polled device
 165  * @dev: device to unregister
 166  *
 167  * The function unregisters previously registered polled input
 168  * device from input layer. Polling is stopped and device is
 169  * ready to be freed with call to input_free_polled_device().
 170  * Callers should not attempt to access dev->input pointer
 171  * after calling this function.
 172  */
 173 void input_unregister_polled_device(struct input_polled_dev *dev)
 174 {
 175         input_unregister_device(dev->input);
 176         dev->input = NULL;
 177 }
 178 EXPORT_SYMBOL(input_unregister_polled_device);
 179