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         /*
 104          * Clean up work struct to remove references to the workqueue.
 105          * It may be destroyed by the next call. This causes problems
 106          * at next device open-close in case of poll_interval == 0.
 107          */
 108         INIT_DELAYED_WORK(&dev->work, dev->work.work.func);
 109         input_polldev_stop_workqueue();
 110
 111         if (dev->close)
 112                 dev->close(dev);
 113 }
 114
 115 /* SYSFS interface */
 116
 117 static ssize_t input_polldev_get_poll(struct device *dev,
 118                                       struct device_attribute *attr, char *buf)
 119 {
 120         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 121
 122         return sprintf(buf, "%d\n", polldev->poll_interval);
 123 }
 124
 125 static ssize_t input_polldev_set_poll(struct device *dev,
 126                                 struct device_attribute *attr, const char *buf,
 127                                 size_t count)
 128 {
 129         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 130         struct input_dev *input = polldev->input;
 131         unsigned long interval;
 132
 133         if (strict_strtoul(buf, 0, &interval))
 134                 return -EINVAL;
 135
 136         if (interval < polldev->poll_interval_min)
 137                 return -EINVAL;
 138
 139         if (interval > polldev->poll_interval_max)
 140                 return -EINVAL;
 141
 142         mutex_lock(&input->mutex);
 143
 144         polldev->poll_interval = interval;
 145
 146         if (input->users) {
 147                 cancel_delayed_work_sync(&polldev->work);
 148                 if (polldev->poll_interval > 0)
 149                         input_polldev_queue_work(polldev);
 150         }
 151
 152         mutex_unlock(&input->mutex);
 153
 154         return count;
 155 }
 156
 157 static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
 158                                             input_polldev_set_poll);
 159
 160
 161 static ssize_t input_polldev_get_max(struct device *dev,
 162                                      struct device_attribute *attr, char *buf)
 163 {
 164         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 165
 166         return sprintf(buf, "%d\n", polldev->poll_interval_max);
 167 }
 168
 169 static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
 170
 171 static ssize_t input_polldev_get_min(struct device *dev,
 172                                      struct device_attribute *attr, char *buf)
 173 {
 174         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 175
 176         return sprintf(buf, "%d\n", polldev->poll_interval_min);
 177 }
 178
 179 static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
 180
 181 static struct attribute *sysfs_attrs[] = {
 182         &dev_attr_poll.attr,
 183         &dev_attr_max.attr,
 184         &dev_attr_min.attr,
 185         NULL
 186 };
 187
 188 static struct attribute_group input_polldev_attribute_group = {
 189         .attrs = sysfs_attrs
 190 };
 191
 192 /**
 193  * input_allocate_polled_device - allocated memory polled device
 194  *
 195  * The function allocates memory for a polled device and also
 196  * for an input device associated with this polled device.
 197  */
 198 struct input_polled_dev *input_allocate_polled_device(void)
 199 {
 200         struct input_polled_dev *dev;
 201
 202         dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
 203         if (!dev)
 204                 return NULL;
 205
 206         dev->input = input_allocate_device();
 207         if (!dev->input) {
 208                 kfree(dev);
 209                 return NULL;
 210         }
 211
 212         return dev;
 213 }
 214 EXPORT_SYMBOL(input_allocate_polled_device);
 215
 216 /**
 217  * input_free_polled_device - free memory allocated for polled device
 218  * @dev: device to free
 219  *
 220  * The function frees memory allocated for polling device and drops
 221  * reference to the associated input device.
 222  */
 223 void input_free_polled_device(struct input_polled_dev *dev)
 224 {
 225         if (dev) {
 226                 input_free_device(dev->input);
 227                 kfree(dev);
 228         }
 229 }
 230 EXPORT_SYMBOL(input_free_polled_device);
 231
 232 /**
 233  * input_register_polled_device - register polled device
 234  * @dev: device to register
 235  *
 236  * The function registers previously initialized polled input device
 237  * with input layer. The device should be allocated with call to
 238  * input_allocate_polled_device(). Callers should also set up poll()
 239  * method and set up capabilities (id, name, phys, bits) of the
 240  * corresponing input_dev structure.
 241  */
 242 int input_register_polled_device(struct input_polled_dev *dev)
 243 {
 244         struct input_dev *input = dev->input;
 245         int error;
 246
 247         input_set_drvdata(input, dev);
 248         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 249         if (!dev->poll_interval)
 250                 dev->poll_interval = 500;
 251         if (!dev->poll_interval_max)
 252                 dev->poll_interval_max = dev->poll_interval;
 253         input->open = input_open_polled_device;
 254         input->close = input_close_polled_device;
 255
 256         error = input_register_device(input);
 257         if (error)
 258                 return error;
 259
 260         error = sysfs_create_group(&input->dev.kobj,
 261                                    &input_polldev_attribute_group);
 262         if (error) {
 263                 input_unregister_device(input);
 264                 return error;
 265         }
 266
 267         /*
 268          * Take extra reference to the underlying input device so
 269          * that it survives call to input_unregister_polled_device()
 270          * and is deleted only after input_free_polled_device()
 271          * has been invoked. This is needed to ease task of freeing
 272          * sparse keymaps.
 273          */
 274         input_get_device(input);
 275
 276         return 0;
 277 }
 278 EXPORT_SYMBOL(input_register_polled_device);
 279
 280 /**
 281  * input_unregister_polled_device - unregister polled device
 282  * @dev: device to unregister
 283  *
 284  * The function unregisters previously registered polled input
 285  * device from input layer. Polling is stopped and device is
 286  * ready to be freed with call to input_free_polled_device().
 287  */
 288 void input_unregister_polled_device(struct input_polled_dev *dev)
 289 {
 290         sysfs_remove_group(&dev->input->dev.kobj,
 291                            &input_polldev_attribute_group);
 292
 293         input_unregister_device(dev->input);
 294 }
 295 EXPORT_SYMBOL(input_unregister_polled_device);
 296