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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/jiffies.h>
  14 #include <linux/slab.h>
  15 #include <linux/mutex.h>
  16 #include <linux/input-polldev.h>
  17
  18 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  19 MODULE_DESCRIPTION("Generic implementation of a polled input device");
  20 MODULE_LICENSE("GPL v2");
  21 MODULE_VERSION("0.1");
  22
  23 static DEFINE_MUTEX(polldev_mutex);
  24 static int polldev_users;
  25 static struct workqueue_struct *polldev_wq;
  26
  27 static int input_polldev_start_workqueue(void)
  28 {
  29         int retval;
  30
  31         retval = mutex_lock_interruptible(&polldev_mutex);
  32         if (retval)
  33                 return retval;
  34
  35         if (!polldev_users) {
  36                 polldev_wq = create_singlethread_workqueue("ipolldevd");
  37                 if (!polldev_wq) {
  38                         pr_err("failed to create ipolldevd workqueue\n");
  39                         retval = -ENOMEM;
  40                         goto out;
  41                 }
  42         }
  43
  44         polldev_users++;
  45
  46  out:
  47         mutex_unlock(&polldev_mutex);
  48         return retval;
  49 }
  50
  51 static void input_polldev_stop_workqueue(void)
  52 {
  53         mutex_lock(&polldev_mutex);
  54
  55         if (!--polldev_users)
  56                 destroy_workqueue(polldev_wq);
  57
  58         mutex_unlock(&polldev_mutex);
  59 }
  60
  61 static void input_polldev_queue_work(struct input_polled_dev *dev)
  62 {
  63         unsigned long delay;
  64
  65         delay = msecs_to_jiffies(dev->poll_interval);
  66         if (delay >= HZ)
  67                 delay = round_jiffies_relative(delay);
  68
  69         queue_delayed_work(polldev_wq, &dev->work, delay);
  70 }
  71
  72 static void input_polled_device_work(struct work_struct *work)
  73 {
  74         struct input_polled_dev *dev =
  75                 container_of(work, struct input_polled_dev, work.work);
  76
  77         dev->poll(dev);
  78         input_polldev_queue_work(dev);
  79 }
  80
  81 static int input_open_polled_device(struct input_dev *input)
  82 {
  83         struct input_polled_dev *dev = input_get_drvdata(input);
  84         int error;
  85
  86         error = input_polldev_start_workqueue();
  87         if (error)
  88                 return error;
  89
  90         if (dev->open)
  91                 dev->open(dev);
  92
  93         /* Only start polling if polling is enabled */
  94         if (dev->poll_interval > 0)
  95                 queue_delayed_work(polldev_wq, &dev->work, 0);
  96
  97         return 0;
  98 }
  99
 100 static void input_close_polled_device(struct input_dev *input)
 101 {
 102         struct input_polled_dev *dev = input_get_drvdata(input);
 103
 104         cancel_delayed_work_sync(&dev->work);
 105         /*
 106          * Clean up work struct to remove references to the workqueue.
 107          * It may be destroyed by the next call. This causes problems
 108          * at next device open-close in case of poll_interval == 0.
 109          */
 110         INIT_DELAYED_WORK(&dev->work, dev->work.work.func);
 111         input_polldev_stop_workqueue();
 112
 113         if (dev->close)
 114                 dev->close(dev);
 115 }
 116
 117 /* SYSFS interface */
 118
 119 static ssize_t input_polldev_get_poll(struct device *dev,
 120                                       struct device_attribute *attr, char *buf)
 121 {
 122         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 123
 124         return sprintf(buf, "%d\n", polldev->poll_interval);
 125 }
 126
 127 static ssize_t input_polldev_set_poll(struct device *dev,
 128                                 struct device_attribute *attr, const char *buf,
 129                                 size_t count)
 130 {
 131         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 132         struct input_dev *input = polldev->input;
 133         unsigned long interval;
 134
 135         if (strict_strtoul(buf, 0, &interval))
 136                 return -EINVAL;
 137
 138         if (interval < polldev->poll_interval_min)
 139                 return -EINVAL;
 140
 141         if (interval > polldev->poll_interval_max)
 142                 return -EINVAL;
 143
 144         mutex_lock(&input->mutex);
 145
 146         polldev->poll_interval = interval;
 147
 148         if (input->users) {
 149                 cancel_delayed_work_sync(&polldev->work);
 150                 if (polldev->poll_interval > 0)
 151                         input_polldev_queue_work(polldev);
 152         }
 153
 154         mutex_unlock(&input->mutex);
 155
 156         return count;
 157 }
 158
 159 static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
 160                                             input_polldev_set_poll);
 161
 162
 163 static ssize_t input_polldev_get_max(struct device *dev,
 164                                      struct device_attribute *attr, char *buf)
 165 {
 166         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 167
 168         return sprintf(buf, "%d\n", polldev->poll_interval_max);
 169 }
 170
 171 static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
 172
 173 static ssize_t input_polldev_get_min(struct device *dev,
 174                                      struct device_attribute *attr, char *buf)
 175 {
 176         struct input_polled_dev *polldev = dev_get_drvdata(dev);
 177
 178         return sprintf(buf, "%d\n", polldev->poll_interval_min);
 179 }
 180
 181 static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
 182
 183 static struct attribute *sysfs_attrs[] = {
 184         &dev_attr_poll.attr,
 185         &dev_attr_max.attr,
 186         &dev_attr_min.attr,
 187         NULL
 188 };
 189
 190 static struct attribute_group input_polldev_attribute_group = {
 191         .attrs = sysfs_attrs
 192 };
 193
 194 /**
 195  * input_allocate_polled_device - allocate memory for polled device
 196  *
 197  * The function allocates memory for a polled device and also
 198  * for an input device associated with this polled device.
 199  */
 200 struct input_polled_dev *input_allocate_polled_device(void)
 201 {
 202         struct input_polled_dev *dev;
 203
 204         dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
 205         if (!dev)
 206                 return NULL;
 207
 208         dev->input = input_allocate_device();
 209         if (!dev->input) {
 210                 kfree(dev);
 211                 return NULL;
 212         }
 213
 214         return dev;
 215 }
 216 EXPORT_SYMBOL(input_allocate_polled_device);
 217
 218 /**
 219  * input_free_polled_device - free memory allocated for polled device
 220  * @dev: device to free
 221  *
 222  * The function frees memory allocated for polling device and drops
 223  * reference to the associated input device.
 224  */
 225 void input_free_polled_device(struct input_polled_dev *dev)
 226 {
 227         if (dev) {
 228                 input_free_device(dev->input);
 229                 kfree(dev);
 230         }
 231 }
 232 EXPORT_SYMBOL(input_free_polled_device);
 233
 234 /**
 235  * input_register_polled_device - register polled device
 236  * @dev: device to register
 237  *
 238  * The function registers previously initialized polled input device
 239  * with input layer. The device should be allocated with call to
 240  * input_allocate_polled_device(). Callers should also set up poll()
 241  * method and set up capabilities (id, name, phys, bits) of the
 242  * corresponding input_dev structure.
 243  */
 244 int input_register_polled_device(struct input_polled_dev *dev)
 245 {
 246         struct input_dev *input = dev->input;
 247         int error;
 248
 249         input_set_drvdata(input, dev);
 250         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 251         if (!dev->poll_interval)
 252                 dev->poll_interval = 500;
 253         if (!dev->poll_interval_max)
 254                 dev->poll_interval_max = dev->poll_interval;
 255         input->open = input_open_polled_device;
 256         input->close = input_close_polled_device;
 257
 258         error = input_register_device(input);
 259         if (error)
 260                 return error;
 261
 262         error = sysfs_create_group(&input->dev.kobj,
 263                                    &input_polldev_attribute_group);
 264         if (error) {
 265                 input_unregister_device(input);
 266                 return error;
 267         }
 268
 269         /*
 270          * Take extra reference to the underlying input device so
 271          * that it survives call to input_unregister_polled_device()
 272          * and is deleted only after input_free_polled_device()
 273          * has been invoked. This is needed to ease task of freeing
 274          * sparse keymaps.
 275          */
 276         input_get_device(input);
 277
 278         return 0;
 279 }
 280 EXPORT_SYMBOL(input_register_polled_device);
 281
 282 /**
 283  * input_unregister_polled_device - unregister polled device
 284  * @dev: device to unregister
 285  *
 286  * The function unregisters previously registered polled input
 287  * device from input layer. Polling is stopped and device is
 288  * ready to be freed with call to input_free_polled_device().
 289  */
 290 void input_unregister_polled_device(struct input_polled_dev *dev)
 291 {
 292         sysfs_remove_group(&dev->input->dev.kobj,
 293                            &input_polldev_attribute_group);
 294
 295         input_unregister_device(dev->input);
 296 }
 297 EXPORT_SYMBOL(input_unregister_polled_device);
 298