drivers/iio/industrialio-event.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Industrial I/O event handling
   3  *
   4  * Copyright (c) 2008 Jonathan Cameron
   5  *
   6  * Based on elements of hwmon and input subsystems.
   7  */
   8
   9 #include <linux/anon_inodes.h>
  10 #include <linux/device.h>
  11 #include <linux/fs.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kfifo.h>
  14 #include <linux/module.h>
  15 #include <linux/poll.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/wait.h>
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/iio-opaque.h>
  22 #include "iio_core.h"
  23 #include <linux/iio/sysfs.h>
  24 #include <linux/iio/events.h>
  25
  26 /**
  27  * struct iio_event_interface - chrdev interface for an event line
  28  * @wait:               wait queue to allow blocking reads of events
  29  * @det_events:         list of detected events
  30  * @dev_attr_list:      list of event interface sysfs attribute
  31  * @flags:              file operations related flags including busy flag.
  32  * @group:              event interface sysfs attribute group
  33  * @read_lock:          lock to protect kfifo read operations
  34  */
  35 struct iio_event_interface {
  36         wait_queue_head_t       wait;
  37         DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  38
  39         struct list_head        dev_attr_list;
  40         unsigned long           flags;
  41         struct attribute_group  group;
  42         struct mutex            read_lock;
  43 };
  44
  45 bool iio_event_enabled(const struct iio_event_interface *ev_int)
  46 {
  47         return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
  48 }
  49
  50 /**
  51  * iio_push_event() - try to add event to the list for userspace reading
  52  * @indio_dev:          IIO device structure
  53  * @ev_code:            What event
  54  * @timestamp:          When the event occurred
  55  *
  56  * Note: The caller must make sure that this function is not running
  57  * concurrently for the same indio_dev more than once.
  58  *
  59  * This function may be safely used as soon as a valid reference to iio_dev has
  60  * been obtained via iio_device_alloc(), but any events that are submitted
  61  * before iio_device_register() has successfully completed will be silently
  62  * discarded.
  63  **/
  64 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  65 {
  66         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
  67         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
  68         struct iio_event_data ev;
  69         int copied;
  70
  71         if (!ev_int)
  72                 return 0;
  73
  74         /* Does anyone care? */
  75         if (iio_event_enabled(ev_int)) {
  76
  77                 ev.id = ev_code;
  78                 ev.timestamp = timestamp;
  79
  80                 copied = kfifo_put(&ev_int->det_events, ev);
  81                 if (copied != 0)
  82                         wake_up_poll(&ev_int->wait, EPOLLIN);
  83         }
  84
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(iio_push_event);
  88
  89 /**
  90  * iio_event_poll() - poll the event queue to find out if it has data
  91  * @filep:      File structure pointer to identify the device
  92  * @wait:       Poll table pointer to add the wait queue on
  93  *
  94  * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
  95  *         or a negative error code on failure
  96  */
  97 static __poll_t iio_event_poll(struct file *filep,
  98                              struct poll_table_struct *wait)
  99 {
 100         struct iio_dev *indio_dev = filep->private_data;
 101         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 102         struct iio_event_interface *ev_int = iio_dev_opaque->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_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 123         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 124         unsigned int copied;
 125         int ret;
 126
 127         if (!indio_dev->info)
 128                 return -ENODEV;
 129
 130         if (count < sizeof(struct iio_event_data))
 131                 return -EINVAL;
 132
 133         do {
 134                 if (kfifo_is_empty(&ev_int->det_events)) {
 135                         if (filep->f_flags & O_NONBLOCK)
 136                                 return -EAGAIN;
 137
 138                         ret = wait_event_interruptible(ev_int->wait,
 139                                         !kfifo_is_empty(&ev_int->det_events) ||
 140                                         indio_dev->info == NULL);
 141                         if (ret)
 142                                 return ret;
 143                         if (indio_dev->info == NULL)
 144                                 return -ENODEV;
 145                 }
 146
 147                 if (mutex_lock_interruptible(&ev_int->read_lock))
 148                         return -ERESTARTSYS;
 149                 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 150                 mutex_unlock(&ev_int->read_lock);
 151
 152                 if (ret)
 153                         return ret;
 154
 155                 /*
 156                  * If we couldn't read anything from the fifo (a different
 157                  * thread might have been faster) we either return -EAGAIN if
 158                  * the file descriptor is non-blocking, otherwise we go back to
 159                  * sleep and wait for more data to arrive.
 160                  */
 161                 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
 162                         return -EAGAIN;
 163
 164         } while (copied == 0);
 165
 166         return copied;
 167 }
 168
 169 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 170 {
 171         struct iio_dev *indio_dev = filep->private_data;
 172         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 173         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 174
 175         clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 176
 177         iio_device_put(indio_dev);
 178
 179         return 0;
 180 }
 181
 182 static const struct file_operations iio_event_chrdev_fileops = {
 183         .read =  iio_event_chrdev_read,
 184         .poll =  iio_event_poll,
 185         .release = iio_event_chrdev_release,
 186         .owner = THIS_MODULE,
 187         .llseek = noop_llseek,
 188 };
 189
 190 int iio_event_getfd(struct iio_dev *indio_dev)
 191 {
 192         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 193         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 194         int fd;
 195
 196         if (ev_int == NULL)
 197                 return -ENODEV;
 198
 199         fd = mutex_lock_interruptible(&indio_dev->mlock);
 200         if (fd)
 201                 return fd;
 202
 203         if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 204                 fd = -EBUSY;
 205                 goto unlock;
 206         }
 207
 208         iio_device_get(indio_dev);
 209
 210         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 211                                 indio_dev, O_RDONLY | O_CLOEXEC);
 212         if (fd < 0) {
 213                 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 214                 iio_device_put(indio_dev);
 215         } else {
 216                 kfifo_reset_out(&ev_int->det_events);
 217         }
 218
 219 unlock:
 220         mutex_unlock(&indio_dev->mlock);
 221         return fd;
 222 }
 223
 224 static const char * const iio_ev_type_text[] = {
 225         [IIO_EV_TYPE_THRESH] = "thresh",
 226         [IIO_EV_TYPE_MAG] = "mag",
 227         [IIO_EV_TYPE_ROC] = "roc",
 228         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 229         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 230         [IIO_EV_TYPE_CHANGE] = "change",
 231 };
 232
 233 static const char * const iio_ev_dir_text[] = {
 234         [IIO_EV_DIR_EITHER] = "either",
 235         [IIO_EV_DIR_RISING] = "rising",
 236         [IIO_EV_DIR_FALLING] = "falling"
 237 };
 238
 239 static const char * const iio_ev_info_text[] = {
 240         [IIO_EV_INFO_ENABLE] = "en",
 241         [IIO_EV_INFO_VALUE] = "value",
 242         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 243         [IIO_EV_INFO_PERIOD] = "period",
 244         [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
 245         [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
 246 };
 247
 248 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
 249 {
 250         return attr->c->event_spec[attr->address & 0xffff].dir;
 251 }
 252
 253 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
 254 {
 255         return attr->c->event_spec[attr->address & 0xffff].type;
 256 }
 257
 258 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
 259 {
 260         return (attr->address >> 16) & 0xffff;
 261 }
 262
 263 static ssize_t iio_ev_state_store(struct device *dev,
 264                                   struct device_attribute *attr,
 265                                   const char *buf,
 266                                   size_t len)
 267 {
 268         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 269         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 270         int ret;
 271         bool val;
 272
 273         ret = strtobool(buf, &val);
 274         if (ret < 0)
 275                 return ret;
 276
 277         ret = indio_dev->info->write_event_config(indio_dev,
 278                 this_attr->c, iio_ev_attr_type(this_attr),
 279                 iio_ev_attr_dir(this_attr), val);
 280
 281         return (ret < 0) ? ret : len;
 282 }
 283
 284 static ssize_t iio_ev_state_show(struct device *dev,
 285                                  struct device_attribute *attr,
 286                                  char *buf)
 287 {
 288         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 289         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 290         int val;
 291
 292         val = indio_dev->info->read_event_config(indio_dev,
 293                 this_attr->c, iio_ev_attr_type(this_attr),
 294                 iio_ev_attr_dir(this_attr));
 295         if (val < 0)
 296                 return val;
 297         else
 298                 return sprintf(buf, "%d\n", val);
 299 }
 300
 301 static ssize_t iio_ev_value_show(struct device *dev,
 302                                  struct device_attribute *attr,
 303                                  char *buf)
 304 {
 305         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 306         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 307         int val, val2, val_arr[2];
 308         int ret;
 309
 310         ret = indio_dev->info->read_event_value(indio_dev,
 311                 this_attr->c, iio_ev_attr_type(this_attr),
 312                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 313                 &val, &val2);
 314         if (ret < 0)
 315                 return ret;
 316         val_arr[0] = val;
 317         val_arr[1] = val2;
 318         return iio_format_value(buf, ret, 2, val_arr);
 319 }
 320
 321 static ssize_t iio_ev_value_store(struct device *dev,
 322                                   struct device_attribute *attr,
 323                                   const char *buf,
 324                                   size_t len)
 325 {
 326         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 327         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 328         int val, val2;
 329         int ret;
 330
 331         if (!indio_dev->info->write_event_value)
 332                 return -EINVAL;
 333
 334         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 335         if (ret)
 336                 return ret;
 337         ret = indio_dev->info->write_event_value(indio_dev,
 338                 this_attr->c, iio_ev_attr_type(this_attr),
 339                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 340                 val, val2);
 341         if (ret < 0)
 342                 return ret;
 343
 344         return len;
 345 }
 346
 347 static int iio_device_add_event(struct iio_dev *indio_dev,
 348         const struct iio_chan_spec *chan, unsigned int spec_index,
 349         enum iio_event_type type, enum iio_event_direction dir,
 350         enum iio_shared_by shared_by, const unsigned long *mask)
 351 {
 352         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 353         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 354         ssize_t (*store)(struct device *, struct device_attribute *,
 355                 const char *, size_t);
 356         unsigned int attrcount = 0;
 357         unsigned int i;
 358         char *postfix;
 359         int ret;
 360
 361         for_each_set_bit(i, mask, sizeof(*mask)*8) {
 362                 if (i >= ARRAY_SIZE(iio_ev_info_text))
 363                         return -EINVAL;
 364                 if (dir != IIO_EV_DIR_NONE)
 365                         postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 366                                         iio_ev_type_text[type],
 367                                         iio_ev_dir_text[dir],
 368                                         iio_ev_info_text[i]);
 369                 else
 370                         postfix = kasprintf(GFP_KERNEL, "%s_%s",
 371                                         iio_ev_type_text[type],
 372                                         iio_ev_info_text[i]);
 373                 if (postfix == NULL)
 374                         return -ENOMEM;
 375
 376                 if (i == IIO_EV_INFO_ENABLE) {
 377                         show = iio_ev_state_show;
 378                         store = iio_ev_state_store;
 379                 } else {
 380                         show = iio_ev_value_show;
 381                         store = iio_ev_value_store;
 382                 }
 383
 384                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 385                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 386                         &iio_dev_opaque->event_interface->dev_attr_list);
 387                 kfree(postfix);
 388
 389                 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
 390                         continue;
 391
 392                 if (ret)
 393                         return ret;
 394
 395                 attrcount++;
 396         }
 397
 398         return attrcount;
 399 }
 400
 401 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 402         struct iio_chan_spec const *chan)
 403 {
 404         int ret = 0, i, attrcount = 0;
 405         enum iio_event_direction dir;
 406         enum iio_event_type type;
 407
 408         for (i = 0; i < chan->num_event_specs; i++) {
 409                 type = chan->event_spec[i].type;
 410                 dir = chan->event_spec[i].dir;
 411
 412                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 413                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 414                 if (ret < 0)
 415                         return ret;
 416                 attrcount += ret;
 417
 418                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 419                         IIO_SHARED_BY_TYPE,
 420                         &chan->event_spec[i].mask_shared_by_type);
 421                 if (ret < 0)
 422                         return ret;
 423                 attrcount += ret;
 424
 425                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 426                         IIO_SHARED_BY_DIR,
 427                         &chan->event_spec[i].mask_shared_by_dir);
 428                 if (ret < 0)
 429                         return ret;
 430                 attrcount += ret;
 431
 432                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 433                         IIO_SHARED_BY_ALL,
 434                         &chan->event_spec[i].mask_shared_by_all);
 435                 if (ret < 0)
 436                         return ret;
 437                 attrcount += ret;
 438         }
 439         ret = attrcount;
 440         return ret;
 441 }
 442
 443 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 444 {
 445         int j, ret, attrcount = 0;
 446
 447         /* Dynamically created from the channels array */
 448         for (j = 0; j < indio_dev->num_channels; j++) {
 449                 ret = iio_device_add_event_sysfs(indio_dev,
 450                                                  &indio_dev->channels[j]);
 451                 if (ret < 0)
 452                         return ret;
 453                 attrcount += ret;
 454         }
 455         return attrcount;
 456 }
 457
 458 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 459 {
 460         int j;
 461
 462         for (j = 0; j < indio_dev->num_channels; j++) {
 463                 if (indio_dev->channels[j].num_event_specs != 0)
 464                         return true;
 465         }
 466         return false;
 467 }
 468
 469 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 470 {
 471         INIT_KFIFO(ev_int->det_events);
 472         init_waitqueue_head(&ev_int->wait);
 473         mutex_init(&ev_int->read_lock);
 474 }
 475
 476 static const char *iio_event_group_name = "events";
 477 int iio_device_register_eventset(struct iio_dev *indio_dev)
 478 {
 479         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 480         struct iio_event_interface *ev_int;
 481         struct iio_dev_attr *p;
 482         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 483         struct attribute **attr;
 484
 485         if (!(indio_dev->info->event_attrs ||
 486               iio_check_for_dynamic_events(indio_dev)))
 487                 return 0;
 488
 489         ev_int = kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 490         if (ev_int == NULL)
 491                 return -ENOMEM;
 492
 493         iio_dev_opaque->event_interface = ev_int;
 494
 495         INIT_LIST_HEAD(&ev_int->dev_attr_list);
 496
 497         iio_setup_ev_int(ev_int);
 498         if (indio_dev->info->event_attrs != NULL) {
 499                 attr = indio_dev->info->event_attrs->attrs;
 500                 while (*attr++ != NULL)
 501                         attrcount_orig++;
 502         }
 503         attrcount = attrcount_orig;
 504         if (indio_dev->channels) {
 505                 ret = __iio_add_event_config_attrs(indio_dev);
 506                 if (ret < 0)
 507                         goto error_free_setup_event_lines;
 508                 attrcount += ret;
 509         }
 510
 511         ev_int->group.name = iio_event_group_name;
 512         ev_int->group.attrs = kcalloc(attrcount + 1,
 513                                       sizeof(ev_int->group.attrs[0]),
 514                                       GFP_KERNEL);
 515         if (ev_int->group.attrs == NULL) {
 516                 ret = -ENOMEM;
 517                 goto error_free_setup_event_lines;
 518         }
 519         if (indio_dev->info->event_attrs)
 520                 memcpy(ev_int->group.attrs,
 521                        indio_dev->info->event_attrs->attrs,
 522                        sizeof(ev_int->group.attrs[0]) * attrcount_orig);
 523         attrn = attrcount_orig;
 524         /* Add all elements from the list. */
 525         list_for_each_entry(p, &ev_int->dev_attr_list, l)
 526                 ev_int->group.attrs[attrn++] = &p->dev_attr.attr;
 527         indio_dev->groups[indio_dev->groupcounter++] = &ev_int->group;
 528
 529         return 0;
 530
 531 error_free_setup_event_lines:
 532         iio_free_chan_devattr_list(&ev_int->dev_attr_list);
 533         kfree(ev_int);
 534         iio_dev_opaque->event_interface = NULL;
 535         return ret;
 536 }
 537
 538 /**
 539  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 540  * @indio_dev: The IIO device
 541  *
 542  * Wakes up the event waitqueue used for poll() and blocking read().
 543  * Should usually be called when the device is unregistered.
 544  */
 545 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 546 {
 547         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 548
 549         if (iio_dev_opaque->event_interface == NULL)
 550                 return;
 551         wake_up(&iio_dev_opaque->event_interface->wait);
 552 }
 553
 554 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 555 {
 556         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 557         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 558
 559         if (ev_int == NULL)
 560                 return;
 561         iio_free_chan_devattr_list(&ev_int->dev_attr_list);
 562         kfree(ev_int->group.attrs);
 563         kfree(ev_int);
 564         iio_dev_opaque->event_interface = NULL;
 565 }