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  * @read_lock:          lock to protect kfifo read operations
  36  */
  37 struct iio_event_interface {
  38         wait_queue_head_t       wait;
  39         DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  40
  41         struct list_head        dev_attr_list;
  42         unsigned long           flags;
  43         struct attribute_group  group;
  44         struct mutex            read_lock;
  45 };
  46
  47 bool iio_event_enabled(const struct iio_event_interface *ev_int)
  48 {
  49         return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
  50 }
  51
  52 /**
  53  * iio_push_event() - try to add event to the list for userspace reading
  54  * @indio_dev:          IIO device structure
  55  * @ev_code:            What event
  56  * @timestamp:          When the event occurred
  57  *
  58  * Note: The caller must make sure that this function is not running
  59  * concurrently for the same indio_dev more than once.
  60  *
  61  * This function may be safely used as soon as a valid reference to iio_dev has
  62  * been obtained via iio_device_alloc(), but any events that are submitted
  63  * before iio_device_register() has successfully completed will be silently
  64  * discarded.
  65  **/
  66 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  67 {
  68         struct iio_event_interface *ev_int = indio_dev->event_interface;
  69         struct iio_event_data ev;
  70         int copied;
  71
  72         if (!ev_int)
  73                 return 0;
  74
  75         /* Does anyone care? */
  76         if (iio_event_enabled(ev_int)) {
  77
  78                 ev.id = ev_code;
  79                 ev.timestamp = timestamp;
  80
  81                 copied = kfifo_put(&ev_int->det_events, ev);
  82                 if (copied != 0)
  83                         wake_up_poll(&ev_int->wait, EPOLLIN);
  84         }
  85
  86         return 0;
  87 }
  88 EXPORT_SYMBOL(iio_push_event);
  89
  90 /**
  91  * iio_event_poll() - poll the event queue to find out if it has data
  92  * @filep:      File structure pointer to identify the device
  93  * @wait:       Poll table pointer to add the wait queue on
  94  *
  95  * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
  96  *         or a negative error code on failure
  97  */
  98 static __poll_t iio_event_poll(struct file *filep,
  99                              struct poll_table_struct *wait)
 100 {
 101         struct iio_dev *indio_dev = filep->private_data;
 102         struct iio_event_interface *ev_int = indio_dev->event_interface;
 103         __poll_t events = 0;
 104
 105         if (!indio_dev->info)
 106                 return events;
 107
 108         poll_wait(filep, &ev_int->wait, wait);
 109
 110         if (!kfifo_is_empty(&ev_int->det_events))
 111                 events = EPOLLIN | EPOLLRDNORM;
 112
 113         return events;
 114 }
 115
 116 static ssize_t iio_event_chrdev_read(struct file *filep,
 117                                      char __user *buf,
 118                                      size_t count,
 119                                      loff_t *f_ps)
 120 {
 121         struct iio_dev *indio_dev = filep->private_data;
 122         struct iio_event_interface *ev_int = indio_dev->event_interface;
 123         unsigned int copied;
 124         int ret;
 125
 126         if (!indio_dev->info)
 127                 return -ENODEV;
 128
 129         if (count < sizeof(struct iio_event_data))
 130                 return -EINVAL;
 131
 132         do {
 133                 if (kfifo_is_empty(&ev_int->det_events)) {
 134                         if (filep->f_flags & O_NONBLOCK)
 135                                 return -EAGAIN;
 136
 137                         ret = wait_event_interruptible(ev_int->wait,
 138                                         !kfifo_is_empty(&ev_int->det_events) ||
 139                                         indio_dev->info == NULL);
 140                         if (ret)
 141                                 return ret;
 142                         if (indio_dev->info == NULL)
 143                                 return -ENODEV;
 144                 }
 145
 146                 if (mutex_lock_interruptible(&ev_int->read_lock))
 147                         return -ERESTARTSYS;
 148                 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 149                 mutex_unlock(&ev_int->read_lock);
 150
 151                 if (ret)
 152                         return ret;
 153
 154                 /*
 155                  * If we couldn't read anything from the fifo (a different
 156                  * thread might have been faster) we either return -EAGAIN if
 157                  * the file descriptor is non-blocking, otherwise we go back to
 158                  * sleep and wait for more data to arrive.
 159                  */
 160                 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
 161                         return -EAGAIN;
 162
 163         } while (copied == 0);
 164
 165         return copied;
 166 }
 167
 168 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 169 {
 170         struct iio_dev *indio_dev = filep->private_data;
 171         struct iio_event_interface *ev_int = indio_dev->event_interface;
 172
 173         clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 174
 175         iio_device_put(indio_dev);
 176
 177         return 0;
 178 }
 179
 180 static const struct file_operations iio_event_chrdev_fileops = {
 181         .read =  iio_event_chrdev_read,
 182         .poll =  iio_event_poll,
 183         .release = iio_event_chrdev_release,
 184         .owner = THIS_MODULE,
 185         .llseek = noop_llseek,
 186 };
 187
 188 int iio_event_getfd(struct iio_dev *indio_dev)
 189 {
 190         struct iio_event_interface *ev_int = indio_dev->event_interface;
 191         int fd;
 192
 193         if (ev_int == NULL)
 194                 return -ENODEV;
 195
 196         fd = mutex_lock_interruptible(&indio_dev->mlock);
 197         if (fd)
 198                 return fd;
 199
 200         if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 201                 fd = -EBUSY;
 202                 goto unlock;
 203         }
 204
 205         iio_device_get(indio_dev);
 206
 207         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 208                                 indio_dev, O_RDONLY | O_CLOEXEC);
 209         if (fd < 0) {
 210                 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 211                 iio_device_put(indio_dev);
 212         } else {
 213                 kfifo_reset_out(&ev_int->det_events);
 214         }
 215
 216 unlock:
 217         mutex_unlock(&indio_dev->mlock);
 218         return fd;
 219 }
 220
 221 static const char * const iio_ev_type_text[] = {
 222         [IIO_EV_TYPE_THRESH] = "thresh",
 223         [IIO_EV_TYPE_MAG] = "mag",
 224         [IIO_EV_TYPE_ROC] = "roc",
 225         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 226         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 227         [IIO_EV_TYPE_CHANGE] = "change",
 228 };
 229
 230 static const char * const iio_ev_dir_text[] = {
 231         [IIO_EV_DIR_EITHER] = "either",
 232         [IIO_EV_DIR_RISING] = "rising",
 233         [IIO_EV_DIR_FALLING] = "falling"
 234 };
 235
 236 static const char * const iio_ev_info_text[] = {
 237         [IIO_EV_INFO_ENABLE] = "en",
 238         [IIO_EV_INFO_VALUE] = "value",
 239         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 240         [IIO_EV_INFO_PERIOD] = "period",
 241         [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
 242         [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
 243 };
 244
 245 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
 246 {
 247         return attr->c->event_spec[attr->address & 0xffff].dir;
 248 }
 249
 250 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
 251 {
 252         return attr->c->event_spec[attr->address & 0xffff].type;
 253 }
 254
 255 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
 256 {
 257         return (attr->address >> 16) & 0xffff;
 258 }
 259
 260 static ssize_t iio_ev_state_store(struct device *dev,
 261                                   struct device_attribute *attr,
 262                                   const char *buf,
 263                                   size_t len)
 264 {
 265         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 266         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 267         int ret;
 268         bool val;
 269
 270         ret = strtobool(buf, &val);
 271         if (ret < 0)
 272                 return ret;
 273
 274         ret = indio_dev->info->write_event_config(indio_dev,
 275                 this_attr->c, iio_ev_attr_type(this_attr),
 276                 iio_ev_attr_dir(this_attr), val);
 277
 278         return (ret < 0) ? ret : len;
 279 }
 280
 281 static ssize_t iio_ev_state_show(struct device *dev,
 282                                  struct device_attribute *attr,
 283                                  char *buf)
 284 {
 285         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 286         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 287         int val;
 288
 289         val = indio_dev->info->read_event_config(indio_dev,
 290                 this_attr->c, iio_ev_attr_type(this_attr),
 291                 iio_ev_attr_dir(this_attr));
 292         if (val < 0)
 293                 return val;
 294         else
 295                 return sprintf(buf, "%d\n", val);
 296 }
 297
 298 static ssize_t iio_ev_value_show(struct device *dev,
 299                                  struct device_attribute *attr,
 300                                  char *buf)
 301 {
 302         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 303         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 304         int val, val2, val_arr[2];
 305         int ret;
 306
 307         ret = indio_dev->info->read_event_value(indio_dev,
 308                 this_attr->c, iio_ev_attr_type(this_attr),
 309                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 310                 &val, &val2);
 311         if (ret < 0)
 312                 return ret;
 313         val_arr[0] = val;
 314         val_arr[1] = val2;
 315         return iio_format_value(buf, ret, 2, val_arr);
 316 }
 317
 318 static ssize_t iio_ev_value_store(struct device *dev,
 319                                   struct device_attribute *attr,
 320                                   const char *buf,
 321                                   size_t len)
 322 {
 323         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 324         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 325         int val, val2;
 326         int ret;
 327
 328         if (!indio_dev->info->write_event_value)
 329                 return -EINVAL;
 330
 331         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 332         if (ret)
 333                 return ret;
 334         ret = indio_dev->info->write_event_value(indio_dev,
 335                 this_attr->c, iio_ev_attr_type(this_attr),
 336                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 337                 val, val2);
 338         if (ret < 0)
 339                 return ret;
 340
 341         return len;
 342 }
 343
 344 static int iio_device_add_event(struct iio_dev *indio_dev,
 345         const struct iio_chan_spec *chan, unsigned int spec_index,
 346         enum iio_event_type type, enum iio_event_direction dir,
 347         enum iio_shared_by shared_by, const unsigned long *mask)
 348 {
 349         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 350         ssize_t (*store)(struct device *, struct device_attribute *,
 351                 const char *, size_t);
 352         unsigned int attrcount = 0;
 353         unsigned int i;
 354         char *postfix;
 355         int ret;
 356
 357         for_each_set_bit(i, mask, sizeof(*mask)*8) {
 358                 if (i >= ARRAY_SIZE(iio_ev_info_text))
 359                         return -EINVAL;
 360                 if (dir != IIO_EV_DIR_NONE)
 361                         postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 362                                         iio_ev_type_text[type],
 363                                         iio_ev_dir_text[dir],
 364                                         iio_ev_info_text[i]);
 365                 else
 366                         postfix = kasprintf(GFP_KERNEL, "%s_%s",
 367                                         iio_ev_type_text[type],
 368                                         iio_ev_info_text[i]);
 369                 if (postfix == NULL)
 370                         return -ENOMEM;
 371
 372                 if (i == IIO_EV_INFO_ENABLE) {
 373                         show = iio_ev_state_show;
 374                         store = iio_ev_state_store;
 375                 } else {
 376                         show = iio_ev_value_show;
 377                         store = iio_ev_value_store;
 378                 }
 379
 380                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 381                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 382                         &indio_dev->event_interface->dev_attr_list);
 383                 kfree(postfix);
 384
 385                 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
 386                         continue;
 387
 388                 if (ret)
 389                         return ret;
 390
 391                 attrcount++;
 392         }
 393
 394         return attrcount;
 395 }
 396
 397 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 398         struct iio_chan_spec const *chan)
 399 {
 400         int ret = 0, i, attrcount = 0;
 401         enum iio_event_direction dir;
 402         enum iio_event_type type;
 403
 404         for (i = 0; i < chan->num_event_specs; i++) {
 405                 type = chan->event_spec[i].type;
 406                 dir = chan->event_spec[i].dir;
 407
 408                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 409                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 410                 if (ret < 0)
 411                         return ret;
 412                 attrcount += ret;
 413
 414                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 415                         IIO_SHARED_BY_TYPE,
 416                         &chan->event_spec[i].mask_shared_by_type);
 417                 if (ret < 0)
 418                         return ret;
 419                 attrcount += ret;
 420
 421                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 422                         IIO_SHARED_BY_DIR,
 423                         &chan->event_spec[i].mask_shared_by_dir);
 424                 if (ret < 0)
 425                         return ret;
 426                 attrcount += ret;
 427
 428                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 429                         IIO_SHARED_BY_ALL,
 430                         &chan->event_spec[i].mask_shared_by_all);
 431                 if (ret < 0)
 432                         return ret;
 433                 attrcount += ret;
 434         }
 435         ret = attrcount;
 436         return ret;
 437 }
 438
 439 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 440 {
 441         int j, ret, attrcount = 0;
 442
 443         /* Dynamically created from the channels array */
 444         for (j = 0; j < indio_dev->num_channels; j++) {
 445                 ret = iio_device_add_event_sysfs(indio_dev,
 446                                                  &indio_dev->channels[j]);
 447                 if (ret < 0)
 448                         return ret;
 449                 attrcount += ret;
 450         }
 451         return attrcount;
 452 }
 453
 454 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 455 {
 456         int j;
 457
 458         for (j = 0; j < indio_dev->num_channels; j++) {
 459                 if (indio_dev->channels[j].num_event_specs != 0)
 460                         return true;
 461         }
 462         return false;
 463 }
 464
 465 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 466 {
 467         INIT_KFIFO(ev_int->det_events);
 468         init_waitqueue_head(&ev_int->wait);
 469         mutex_init(&ev_int->read_lock);
 470 }
 471
 472 static const char *iio_event_group_name = "events";
 473 int iio_device_register_eventset(struct iio_dev *indio_dev)
 474 {
 475         struct iio_dev_attr *p;
 476         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 477         struct attribute **attr;
 478
 479         if (!(indio_dev->info->event_attrs ||
 480               iio_check_for_dynamic_events(indio_dev)))
 481                 return 0;
 482
 483         indio_dev->event_interface =
 484                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 485         if (indio_dev->event_interface == NULL)
 486                 return -ENOMEM;
 487
 488         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 489
 490         iio_setup_ev_int(indio_dev->event_interface);
 491         if (indio_dev->info->event_attrs != NULL) {
 492                 attr = indio_dev->info->event_attrs->attrs;
 493                 while (*attr++ != NULL)
 494                         attrcount_orig++;
 495         }
 496         attrcount = attrcount_orig;
 497         if (indio_dev->channels) {
 498                 ret = __iio_add_event_config_attrs(indio_dev);
 499                 if (ret < 0)
 500                         goto error_free_setup_event_lines;
 501                 attrcount += ret;
 502         }
 503
 504         indio_dev->event_interface->group.name = iio_event_group_name;
 505         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 506                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 507                                                           GFP_KERNEL);
 508         if (indio_dev->event_interface->group.attrs == NULL) {
 509                 ret = -ENOMEM;
 510                 goto error_free_setup_event_lines;
 511         }
 512         if (indio_dev->info->event_attrs)
 513                 memcpy(indio_dev->event_interface->group.attrs,
 514                        indio_dev->info->event_attrs->attrs,
 515                        sizeof(indio_dev->event_interface->group.attrs[0])
 516                        *attrcount_orig);
 517         attrn = attrcount_orig;
 518         /* Add all elements from the list. */
 519         list_for_each_entry(p,
 520                             &indio_dev->event_interface->dev_attr_list,
 521                             l)
 522                 indio_dev->event_interface->group.attrs[attrn++] =
 523                         &p->dev_attr.attr;
 524         indio_dev->groups[indio_dev->groupcounter++] =
 525                 &indio_dev->event_interface->group;
 526
 527         return 0;
 528
 529 error_free_setup_event_lines:
 530         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 531         kfree(indio_dev->event_interface);
 532         indio_dev->event_interface = NULL;
 533         return ret;
 534 }
 535
 536 /**
 537  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 538  * @indio_dev: The IIO device
 539  *
 540  * Wakes up the event waitqueue used for poll() and blocking read().
 541  * Should usually be called when the device is unregistered.
 542  */
 543 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 544 {
 545         if (indio_dev->event_interface == NULL)
 546                 return;
 547         wake_up(&indio_dev->event_interface->wait);
 548 }
 549
 550 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 551 {
 552         if (indio_dev->event_interface == NULL)
 553                 return;
 554         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 555         kfree(indio_dev->event_interface->group.attrs);
 556         kfree(indio_dev->event_interface);
 557 }