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_polldev_queue_work(struct input_polled_dev *dev)
  60 {
  61         unsigned long delay;
  62
  63         delay = msecs_to_jiffies(dev->poll_interval);
  64         if (delay >= HZ)
  65                 delay = round_jiffies_relative(delay);
  66
  67         queue_delayed_work(polldev_wq, &dev->work, delay);
  68 }
  69
  70 static void input_polled_device_work(struct work_struct *work)
  71 {
  72         struct input_polled_dev *dev =
  73                 container_of(work, struct input_polled_dev, work.work);
  74
  75         dev->poll(dev);
  76         input_polldev_queue_work(dev);
  77 }
  78
  79 static int input_open_polled_device(struct input_dev *input)
  80 {
  81         struct input_polled_dev *dev = input_get_drvdata(input);
  82         int error;
  83
  84         error = input_polldev_start_workqueue();
  85         if (error)
  86                 return error;
  87
  88         if (dev->open)
  89                 dev->open(dev);
  90
  91         /* Only start polling if polling is enabled */
  92         if (dev->poll_interval > 0)
  93                 queue_delayed_work(polldev_wq, &dev->work, 0);
  94
  95         return 0;
  96 }
  97
  98 static void input_close_polled_device(struct input_dev *input)
  99 {
 100         struct input_polled_dev *dev = input_get_drvdata(input);
 101
 102         cancel_delayed_work_sync(&dev->work);
 103         input_polldev_stop_workqueue();
 104
 105         if (dev->close)
 106                 dev->close(dev);
 107 }
 108
 109 /* SYSFS interface */
 110
 111 static ssize_t input_polldev_get_poll(struct device *dev,
 112                                       struct device_attribute *attr, char *buf)
 113 {
 114         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 115
 116         return sprintf(buf, "%d\n", polldev->poll_interval);
 117 }
 118
 119 static ssize_t input_polldev_set_poll(struct device *dev,
 120                                 struct device_attribute *attr, const char *buf,
 121                                 size_t count)
 122 {
 123         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 124         struct input_dev *input = polldev->input;
 125         unsigned long interval;
 126
 127         if (strict_strtoul(buf, 0, &interval))
 128                 return -EINVAL;
 129
 130         if (interval < polldev->poll_interval_min)
 131                 return -EINVAL;
 132
 133         if (interval > polldev->poll_interval_max)
 134                 return -EINVAL;
 135
 136         mutex_lock(&input->mutex);
 137
 138         polldev->poll_interval = interval;
 139
 140         if (input->users) {
 141                 cancel_delayed_work_sync(&polldev->work);
 142                 if (polldev->poll_interval > 0)
 143                         input_polldev_queue_work(polldev);
 144         }
 145
 146         mutex_unlock(&input->mutex);
 147
 148         return count;
 149 }
 150
 151 static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
 152                                             input_polldev_set_poll);
 153
 154
 155 static ssize_t input_polldev_get_max(struct device *dev,
 156                                      struct device_attribute *attr, char *buf)
 157 {
 158         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 159
 160         return sprintf(buf, "%d\n", polldev->poll_interval_max);
 161 }
 162
 163 static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
 164
 165 static ssize_t input_polldev_get_min(struct device *dev,
 166                                      struct device_attribute *attr, char *buf)
 167 {
 168         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 169
 170         return sprintf(buf, "%d\n", polldev->poll_interval_min);
 171 }
 172
 173 static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
 174
 175 static struct attribute *sysfs_attrs[] = {
 176         &dev_attr_poll.attr,
 177         &dev_attr_max.attr,
 178         &dev_attr_min.attr,
 179         NULL
 180 };
 181
 182 static struct attribute_group input_polldev_attribute_group = {
 183         .attrs = sysfs_attrs
 184 };
 185
 186 /**
 187  * input_allocate_polled_device - allocated memory polled device
 188  *
 189  * The function allocates memory for a polled device and also
 190  * for an input device associated with this polled device.
 191  */
 192 struct input_polled_dev *input_allocate_polled_device(void)
 193 {
 194         struct input_polled_dev *dev;
 195
 196         dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
 197         if (!dev)
 198                 return NULL;
 199
 200         dev->input = input_allocate_device();
 201         if (!dev->input) {
 202                 kfree(dev);
 203                 return NULL;
 204         }
 205
 206         return dev;
 207 }
 208 EXPORT_SYMBOL(input_allocate_polled_device);
 209
 210 /**
 211  * input_free_polled_device - free memory allocated for polled device
 212  * @dev: device to free
 213  *
 214  * The function frees memory allocated for polling device and drops
 215  * reference to the associated input device.
 216  */
 217 void input_free_polled_device(struct input_polled_dev *dev)
 218 {
 219         if (dev) {
 220                 input_free_device(dev->input);
 221                 kfree(dev);
 222         }
 223 }
 224 EXPORT_SYMBOL(input_free_polled_device);
 225
 226 /**
 227  * input_register_polled_device - register polled device
 228  * @dev: device to register
 229  *
 230  * The function registers previously initialized polled input device
 231  * with input layer. The device should be allocated with call to
 232  * input_allocate_polled_device(). Callers should also set up poll()
 233  * method and set up capabilities (id, name, phys, bits) of the
 234  * corresponing input_dev structure.
 235  */
 236 int input_register_polled_device(struct input_polled_dev *dev)
 237 {
 238         struct input_dev *input = dev->input;
 239         int error;
 240
 241         input_set_drvdata(input, dev);
 242         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 243         if (!dev->poll_interval)
 244                 dev->poll_interval = 500;
 245         if (!dev->poll_interval_max)
 246                 dev->poll_interval_max = dev->poll_interval;
 247         input->open = input_open_polled_device;
 248         input->close = input_close_polled_device;
 249
 250         error = input_register_device(input);
 251         if (error)
 252                 return error;
 253
 254         error = sysfs_create_group(&input->dev.kobj,
 255                                    &input_polldev_attribute_group);
 256         if (error) {
 257                 input_unregister_device(input);
 258                 return error;
 259         }
 260
 261         /*
 262          * Take extra reference to the underlying input device so
 263          * that it survives call to input_unregister_polled_device()
 264          * and is deleted only after input_free_polled_device()
 265          * has been invoked. This is needed to ease task of freeing
 266          * sparse keymaps.
 267          */
 268         input_get_device(input);
 269
 270         return 0;
 271 }
 272 EXPORT_SYMBOL(input_register_polled_device);
 273
 274 /**
 275  * input_unregister_polled_device - unregister polled device
 276  * @dev: device to unregister
 277  *
 278  * The function unregisters previously registered polled input
 279  * device from input layer. Polling is stopped and device is
 280  * ready to be freed with call to input_free_polled_device().
 281  */
 282 void input_unregister_polled_device(struct input_polled_dev *dev)
 283 {
 284         sysfs_remove_group(&dev->input->dev.kobj,
 285                            &input_polldev_attribute_group);
 286
 287         input_unregister_device(dev->input);
 288 }
 289 EXPORT_SYMBOL(input_unregister_polled_device);
 290