drivers/iio/industrialio-event.c

   1 /* Industrial I/O event handling
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * Based on elements of hwmon and input subsystems.
  10  */
  11
  12 #include <linux/anon_inodes.h>
  13 #include <linux/device.h>
  14 #include <linux/fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/kfifo.h>
  17 #include <linux/module.h>
  18 #include <linux/poll.h>
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/wait.h>
  23 #include <linux/iio/iio.h>
  24 #include "iio_core.h"
  25 #include <linux/iio/sysfs.h>
  26 #include <linux/iio/events.h>
  27
  28 /**
  29  * struct iio_event_interface - chrdev interface for an event line
  30  * @wait:               wait queue to allow blocking reads of events
  31  * @det_events:         list of detected events
  32  * @dev_attr_list:      list of event interface sysfs attribute
  33  * @flags:              file operations related flags including busy flag.
  34  * @group:              event interface sysfs attribute group
  35  */
  36 struct iio_event_interface {
  37         wait_queue_head_t       wait;
  38         DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  39
  40         struct list_head        dev_attr_list;
  41         unsigned long           flags;
  42         struct attribute_group  group;
  43 };
  44
  45 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  46 {
  47         struct iio_event_interface *ev_int = indio_dev->event_interface;
  48         struct iio_event_data ev;
  49         unsigned long flags;
  50         int copied;
  51
  52         /* Does anyone care? */
  53         spin_lock_irqsave(&ev_int->wait.lock, flags);
  54         if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  55
  56                 ev.id = ev_code;
  57                 ev.timestamp = timestamp;
  58
  59                 copied = kfifo_put(&ev_int->det_events, &ev);
  60                 if (copied != 0)
  61                         wake_up_locked_poll(&ev_int->wait, POLLIN);
  62         }
  63         spin_unlock_irqrestore(&ev_int->wait.lock, flags);
  64
  65         return 0;
  66 }
  67 EXPORT_SYMBOL(iio_push_event);
  68
  69 /**
  70  * iio_event_poll() - poll the event queue to find out if it has data
  71  */
  72 static unsigned int iio_event_poll(struct file *filep,
  73                              struct poll_table_struct *wait)
  74 {
  75         struct iio_dev *indio_dev = filep->private_data;
  76         struct iio_event_interface *ev_int = indio_dev->event_interface;
  77         unsigned int events = 0;
  78
  79         poll_wait(filep, &ev_int->wait, wait);
  80
  81         spin_lock_irq(&ev_int->wait.lock);
  82         if (!kfifo_is_empty(&ev_int->det_events))
  83                 events = POLLIN | POLLRDNORM;
  84         spin_unlock_irq(&ev_int->wait.lock);
  85
  86         return events;
  87 }
  88
  89 static ssize_t iio_event_chrdev_read(struct file *filep,
  90                                      char __user *buf,
  91                                      size_t count,
  92                                      loff_t *f_ps)
  93 {
  94         struct iio_dev *indio_dev = filep->private_data;
  95         struct iio_event_interface *ev_int = indio_dev->event_interface;
  96         unsigned int copied;
  97         int ret;
  98
  99         if (count < sizeof(struct iio_event_data))
 100                 return -EINVAL;
 101
 102         spin_lock_irq(&ev_int->wait.lock);
 103         if (kfifo_is_empty(&ev_int->det_events)) {
 104                 if (filep->f_flags & O_NONBLOCK) {
 105                         ret = -EAGAIN;
 106                         goto error_unlock;
 107                 }
 108                 /* Blocking on device; waiting for something to be there */
 109                 ret = wait_event_interruptible_locked_irq(ev_int->wait,
 110                                         !kfifo_is_empty(&ev_int->det_events));
 111                 if (ret)
 112                         goto error_unlock;
 113                 /* Single access device so no one else can get the data */
 114         }
 115
 116         ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 117
 118 error_unlock:
 119         spin_unlock_irq(&ev_int->wait.lock);
 120
 121         return ret ? ret : copied;
 122 }
 123
 124 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 125 {
 126         struct iio_dev *indio_dev = filep->private_data;
 127         struct iio_event_interface *ev_int = indio_dev->event_interface;
 128
 129         spin_lock_irq(&ev_int->wait.lock);
 130         __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 131         /*
 132          * In order to maintain a clean state for reopening,
 133          * clear out any awaiting events. The mask will prevent
 134          * any new __iio_push_event calls running.
 135          */
 136         kfifo_reset_out(&ev_int->det_events);
 137         spin_unlock_irq(&ev_int->wait.lock);
 138
 139         iio_device_put(indio_dev);
 140
 141         return 0;
 142 }
 143
 144 static const struct file_operations iio_event_chrdev_fileops = {
 145         .read =  iio_event_chrdev_read,
 146         .poll =  iio_event_poll,
 147         .release = iio_event_chrdev_release,
 148         .owner = THIS_MODULE,
 149         .llseek = noop_llseek,
 150 };
 151
 152 int iio_event_getfd(struct iio_dev *indio_dev)
 153 {
 154         struct iio_event_interface *ev_int = indio_dev->event_interface;
 155         int fd;
 156
 157         if (ev_int == NULL)
 158                 return -ENODEV;
 159
 160         spin_lock_irq(&ev_int->wait.lock);
 161         if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 162                 spin_unlock_irq(&ev_int->wait.lock);
 163                 return -EBUSY;
 164         }
 165         spin_unlock_irq(&ev_int->wait.lock);
 166         iio_device_get(indio_dev);
 167
 168         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 169                                 indio_dev, O_RDONLY);
 170         if (fd < 0) {
 171                 spin_lock_irq(&ev_int->wait.lock);
 172                 __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 173                 spin_unlock_irq(&ev_int->wait.lock);
 174                 iio_device_put(indio_dev);
 175         }
 176         return fd;
 177 }
 178
 179 static const char * const iio_ev_type_text[] = {
 180         [IIO_EV_TYPE_THRESH] = "thresh",
 181         [IIO_EV_TYPE_MAG] = "mag",
 182         [IIO_EV_TYPE_ROC] = "roc",
 183         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 184         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 185 };
 186
 187 static const char * const iio_ev_dir_text[] = {
 188         [IIO_EV_DIR_EITHER] = "either",
 189         [IIO_EV_DIR_RISING] = "rising",
 190         [IIO_EV_DIR_FALLING] = "falling"
 191 };
 192
 193 static ssize_t iio_ev_state_store(struct device *dev,
 194                                   struct device_attribute *attr,
 195                                   const char *buf,
 196                                   size_t len)
 197 {
 198         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 199         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 200         int ret;
 201         bool val;
 202
 203         ret = strtobool(buf, &val);
 204         if (ret < 0)
 205                 return ret;
 206
 207         ret = indio_dev->info->write_event_config(indio_dev,
 208                                                   this_attr->address,
 209                                                   val);
 210         return (ret < 0) ? ret : len;
 211 }
 212
 213 static ssize_t iio_ev_state_show(struct device *dev,
 214                                  struct device_attribute *attr,
 215                                  char *buf)
 216 {
 217         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 218         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 219         int val = indio_dev->info->read_event_config(indio_dev,
 220                                                      this_attr->address);
 221
 222         if (val < 0)
 223                 return val;
 224         else
 225                 return sprintf(buf, "%d\n", val);
 226 }
 227
 228 static ssize_t iio_ev_value_show(struct device *dev,
 229                                  struct device_attribute *attr,
 230                                  char *buf)
 231 {
 232         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 233         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 234         int val, ret;
 235
 236         ret = indio_dev->info->read_event_value(indio_dev,
 237                                                 this_attr->address, &val);
 238         if (ret < 0)
 239                 return ret;
 240
 241         return sprintf(buf, "%d\n", val);
 242 }
 243
 244 static ssize_t iio_ev_value_store(struct device *dev,
 245                                   struct device_attribute *attr,
 246                                   const char *buf,
 247                                   size_t len)
 248 {
 249         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 250         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 251         int val;
 252         int ret;
 253
 254         if (!indio_dev->info->write_event_value)
 255                 return -EINVAL;
 256
 257         ret = kstrtoint(buf, 10, &val);
 258         if (ret)
 259                 return ret;
 260
 261         ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
 262                                                  val);
 263         if (ret < 0)
 264                 return ret;
 265
 266         return len;
 267 }
 268
 269 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 270                                       struct iio_chan_spec const *chan)
 271 {
 272         int ret = 0, i, attrcount = 0;
 273         u64 mask = 0;
 274         char *postfix;
 275         if (!chan->event_mask)
 276                 return 0;
 277
 278         for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
 279                 postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
 280                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 281                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 282                 if (postfix == NULL) {
 283                         ret = -ENOMEM;
 284                         goto error_ret;
 285                 }
 286                 if (chan->modified)
 287                         mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel2,
 288                                                   i/IIO_EV_DIR_MAX,
 289                                                   i%IIO_EV_DIR_MAX);
 290                 else if (chan->differential)
 291                         mask = IIO_EVENT_CODE(chan->type,
 292                                               0, 0,
 293                                               i%IIO_EV_DIR_MAX,
 294                                               i/IIO_EV_DIR_MAX,
 295                                               0,
 296                                               chan->channel,
 297                                               chan->channel2);
 298                 else
 299                         mask = IIO_UNMOD_EVENT_CODE(chan->type,
 300                                                     chan->channel,
 301                                                     i/IIO_EV_DIR_MAX,
 302                                                     i%IIO_EV_DIR_MAX);
 303
 304                 ret = __iio_add_chan_devattr(postfix,
 305                                              chan,
 306                                              &iio_ev_state_show,
 307                                              iio_ev_state_store,
 308                                              mask,
 309                                              0,
 310                                              &indio_dev->dev,
 311                                              &indio_dev->event_interface->
 312                                              dev_attr_list);
 313                 kfree(postfix);
 314                 if (ret)
 315                         goto error_ret;
 316                 attrcount++;
 317                 postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
 318                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 319                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 320                 if (postfix == NULL) {
 321                         ret = -ENOMEM;
 322                         goto error_ret;
 323                 }
 324                 ret = __iio_add_chan_devattr(postfix, chan,
 325                                              iio_ev_value_show,
 326                                              iio_ev_value_store,
 327                                              mask,
 328                                              0,
 329                                              &indio_dev->dev,
 330                                              &indio_dev->event_interface->
 331                                              dev_attr_list);
 332                 kfree(postfix);
 333                 if (ret)
 334                         goto error_ret;
 335                 attrcount++;
 336         }
 337         ret = attrcount;
 338 error_ret:
 339         return ret;
 340 }
 341
 342 static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
 343 {
 344         struct iio_dev_attr *p, *n;
 345         list_for_each_entry_safe(p, n,
 346                                  &indio_dev->event_interface->
 347                                  dev_attr_list, l) {
 348                 kfree(p->dev_attr.attr.name);
 349                 kfree(p);
 350         }
 351 }
 352
 353 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 354 {
 355         int j, ret, attrcount = 0;
 356
 357         /* Dynically created from the channels array */
 358         for (j = 0; j < indio_dev->num_channels; j++) {
 359                 ret = iio_device_add_event_sysfs(indio_dev,
 360                                                  &indio_dev->channels[j]);
 361                 if (ret < 0)
 362                         return ret;
 363                 attrcount += ret;
 364         }
 365         return attrcount;
 366 }
 367
 368 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 369 {
 370         int j;
 371
 372         for (j = 0; j < indio_dev->num_channels; j++)
 373                 if (indio_dev->channels[j].event_mask != 0)
 374                         return true;
 375         return false;
 376 }
 377
 378 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 379 {
 380         INIT_KFIFO(ev_int->det_events);
 381         init_waitqueue_head(&ev_int->wait);
 382 }
 383
 384 static const char *iio_event_group_name = "events";
 385 int iio_device_register_eventset(struct iio_dev *indio_dev)
 386 {
 387         struct iio_dev_attr *p;
 388         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 389         struct attribute **attr;
 390
 391         if (!(indio_dev->info->event_attrs ||
 392               iio_check_for_dynamic_events(indio_dev)))
 393                 return 0;
 394
 395         indio_dev->event_interface =
 396                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 397         if (indio_dev->event_interface == NULL) {
 398                 ret = -ENOMEM;
 399                 goto error_ret;
 400         }
 401
 402         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 403
 404         iio_setup_ev_int(indio_dev->event_interface);
 405         if (indio_dev->info->event_attrs != NULL) {
 406                 attr = indio_dev->info->event_attrs->attrs;
 407                 while (*attr++ != NULL)
 408                         attrcount_orig++;
 409         }
 410         attrcount = attrcount_orig;
 411         if (indio_dev->channels) {
 412                 ret = __iio_add_event_config_attrs(indio_dev);
 413                 if (ret < 0)
 414                         goto error_free_setup_event_lines;
 415                 attrcount += ret;
 416         }
 417
 418         indio_dev->event_interface->group.name = iio_event_group_name;
 419         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 420                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 421                                                           GFP_KERNEL);
 422         if (indio_dev->event_interface->group.attrs == NULL) {
 423                 ret = -ENOMEM;
 424                 goto error_free_setup_event_lines;
 425         }
 426         if (indio_dev->info->event_attrs)
 427                 memcpy(indio_dev->event_interface->group.attrs,
 428                        indio_dev->info->event_attrs->attrs,
 429                        sizeof(indio_dev->event_interface->group.attrs[0])
 430                        *attrcount_orig);
 431         attrn = attrcount_orig;
 432         /* Add all elements from the list. */
 433         list_for_each_entry(p,
 434                             &indio_dev->event_interface->dev_attr_list,
 435                             l)
 436                 indio_dev->event_interface->group.attrs[attrn++] =
 437                         &p->dev_attr.attr;
 438         indio_dev->groups[indio_dev->groupcounter++] =
 439                 &indio_dev->event_interface->group;
 440
 441         return 0;
 442
 443 error_free_setup_event_lines:
 444         __iio_remove_event_config_attrs(indio_dev);
 445         kfree(indio_dev->event_interface);
 446 error_ret:
 447
 448         return ret;
 449 }
 450
 451 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 452 {
 453         if (indio_dev->event_interface == NULL)
 454                 return;
 455         __iio_remove_event_config_attrs(indio_dev);
 456         kfree(indio_dev->event_interface->group.attrs);
 457         kfree(indio_dev->event_interface);
 458 }