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         unsigned long delay;
  64
  65         dev->poll(dev);
  66
  67         delay = msecs_to_jiffies(dev->poll_interval);
  68         if (delay >= HZ)
  69                 delay = round_jiffies_relative(delay);
  70
  71         queue_delayed_work(polldev_wq, &dev->work, delay);
  72 }
  73
  74 static int input_open_polled_device(struct input_dev *input)
  75 {
  76         struct input_polled_dev *dev = input->private;
  77         int error;
  78
  79         error = input_polldev_start_workqueue();
  80         if (error)
  81                 return error;
  82
  83         if (dev->flush)
  84                 dev->flush(dev);
  85
  86         queue_delayed_work(polldev_wq, &dev->work,
  87                            msecs_to_jiffies(dev->poll_interval));
  88
  89         return 0;
  90 }
  91
  92 static void input_close_polled_device(struct input_dev *input)
  93 {
  94         struct input_polled_dev *dev = input->private;
  95
  96         cancel_delayed_work_sync(&dev->work);
  97         input_polldev_stop_workqueue();
  98 }
  99
 100 /**
 101  * input_allocate_polled_device - allocated memory polled device
 102  *
 103  * The function allocates memory for a polled device and also
 104  * for an input device associated with this polled device.
 105  */
 106 struct input_polled_dev *input_allocate_polled_device(void)
 107 {
 108         struct input_polled_dev *dev;
 109
 110         dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
 111         if (!dev)
 112                 return NULL;
 113
 114         dev->input = input_allocate_device();
 115         if (!dev->input) {
 116                 kfree(dev);
 117                 return NULL;
 118         }
 119
 120         return dev;
 121 }
 122 EXPORT_SYMBOL(input_allocate_polled_device);
 123
 124 /**
 125  * input_free_polled_device - free memory allocated for polled device
 126  * @dev: device to free
 127  *
 128  * The function frees memory allocated for polling device and drops
 129  * reference to the associated input device (if present).
 130  */
 131 void input_free_polled_device(struct input_polled_dev *dev)
 132 {
 133         if (dev) {
 134                 input_free_device(dev->input);
 135                 kfree(dev);
 136         }
 137 }
 138 EXPORT_SYMBOL(input_free_polled_device);
 139
 140 /**
 141  * input_register_polled_device - register polled device
 142  * @dev: device to register
 143  *
 144  * The function registers previously initialized polled input device
 145  * with input layer. The device should be allocated with call to
 146  * input_allocate_polled_device(). Callers should also set up poll()
 147  * method and set up capabilities (id, name, phys, bits) of the
 148  * corresponing input_dev structure.
 149  */
 150 int input_register_polled_device(struct input_polled_dev *dev)
 151 {
 152         struct input_dev *input = dev->input;
 153
 154         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 155         if (!dev->poll_interval)
 156                 dev->poll_interval = 500;
 157         input->private = dev;
 158         input->open = input_open_polled_device;
 159         input->close = input_close_polled_device;
 160
 161         return input_register_device(input);
 162 }
 163 EXPORT_SYMBOL(input_register_polled_device);
 164
 165 /**
 166  * input_unregister_polled_device - unregister polled device
 167  * @dev: device to unregister
 168  *
 169  * The function unregisters previously registered polled input
 170  * device from input layer. Polling is stopped and device is
 171  * ready to be freed with call to input_free_polled_device().
 172  * Callers should not attempt to access dev->input pointer
 173  * after calling this function.
 174  */
 175 void input_unregister_polled_device(struct input_polled_dev *dev)
 176 {
 177         input_unregister_device(dev->input);
 178         dev->input = NULL;
 179 }
 180 EXPORT_SYMBOL(input_unregister_polled_device);
 181