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  * @ioctl_handler:      handler for event ioctl() calls
  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         struct mutex            read_lock;
  44         struct iio_ioctl_handler        ioctl_handler;
  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_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
  69         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
  70         struct iio_event_data ev;
  71         int copied;
  72
  73         if (!ev_int)
  74                 return 0;
  75
  76         /* Does anyone care? */
  77         if (iio_event_enabled(ev_int)) {
  78
  79                 ev.id = ev_code;
  80                 ev.timestamp = timestamp;
  81
  82                 copied = kfifo_put(&ev_int->det_events, ev);
  83                 if (copied != 0)
  84                         wake_up_poll(&ev_int->wait, EPOLLIN);
  85         }
  86
  87         return 0;
  88 }
  89 EXPORT_SYMBOL(iio_push_event);
  90
  91 /**
  92  * iio_event_poll() - poll the event queue to find out if it has data
  93  * @filep:      File structure pointer to identify the device
  94  * @wait:       Poll table pointer to add the wait queue on
  95  *
  96  * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
  97  *         or a negative error code on failure
  98  */
  99 static __poll_t iio_event_poll(struct file *filep,
 100                              struct poll_table_struct *wait)
 101 {
 102         struct iio_dev *indio_dev = filep->private_data;
 103         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 104         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 105         __poll_t events = 0;
 106
 107         if (!indio_dev->info)
 108                 return events;
 109
 110         poll_wait(filep, &ev_int->wait, wait);
 111
 112         if (!kfifo_is_empty(&ev_int->det_events))
 113                 events = EPOLLIN | EPOLLRDNORM;
 114
 115         return events;
 116 }
 117
 118 static ssize_t iio_event_chrdev_read(struct file *filep,
 119                                      char __user *buf,
 120                                      size_t count,
 121                                      loff_t *f_ps)
 122 {
 123         struct iio_dev *indio_dev = filep->private_data;
 124         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 125         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 126         unsigned int copied;
 127         int ret;
 128
 129         if (!indio_dev->info)
 130                 return -ENODEV;
 131
 132         if (count < sizeof(struct iio_event_data))
 133                 return -EINVAL;
 134
 135         do {
 136                 if (kfifo_is_empty(&ev_int->det_events)) {
 137                         if (filep->f_flags & O_NONBLOCK)
 138                                 return -EAGAIN;
 139
 140                         ret = wait_event_interruptible(ev_int->wait,
 141                                         !kfifo_is_empty(&ev_int->det_events) ||
 142                                         indio_dev->info == NULL);
 143                         if (ret)
 144                                 return ret;
 145                         if (indio_dev->info == NULL)
 146                                 return -ENODEV;
 147                 }
 148
 149                 if (mutex_lock_interruptible(&ev_int->read_lock))
 150                         return -ERESTARTSYS;
 151                 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 152                 mutex_unlock(&ev_int->read_lock);
 153
 154                 if (ret)
 155                         return ret;
 156
 157                 /*
 158                  * If we couldn't read anything from the fifo (a different
 159                  * thread might have been faster) we either return -EAGAIN if
 160                  * the file descriptor is non-blocking, otherwise we go back to
 161                  * sleep and wait for more data to arrive.
 162                  */
 163                 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
 164                         return -EAGAIN;
 165
 166         } while (copied == 0);
 167
 168         return copied;
 169 }
 170
 171 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 172 {
 173         struct iio_dev *indio_dev = filep->private_data;
 174         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 175         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 176
 177         clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 178
 179         iio_device_put(indio_dev);
 180
 181         return 0;
 182 }
 183
 184 static const struct file_operations iio_event_chrdev_fileops = {
 185         .read =  iio_event_chrdev_read,
 186         .poll =  iio_event_poll,
 187         .release = iio_event_chrdev_release,
 188         .owner = THIS_MODULE,
 189         .llseek = noop_llseek,
 190 };
 191
 192 static int iio_event_getfd(struct iio_dev *indio_dev)
 193 {
 194         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 195         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 196         int fd;
 197
 198         if (ev_int == NULL)
 199                 return -ENODEV;
 200
 201         fd = mutex_lock_interruptible(&indio_dev->mlock);
 202         if (fd)
 203                 return fd;
 204
 205         if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 206                 fd = -EBUSY;
 207                 goto unlock;
 208         }
 209
 210         iio_device_get(indio_dev);
 211
 212         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 213                                 indio_dev, O_RDONLY | O_CLOEXEC);
 214         if (fd < 0) {
 215                 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 216                 iio_device_put(indio_dev);
 217         } else {
 218                 kfifo_reset_out(&ev_int->det_events);
 219         }
 220
 221 unlock:
 222         mutex_unlock(&indio_dev->mlock);
 223         return fd;
 224 }
 225
 226 static const char * const iio_ev_type_text[] = {
 227         [IIO_EV_TYPE_THRESH] = "thresh",
 228         [IIO_EV_TYPE_MAG] = "mag",
 229         [IIO_EV_TYPE_ROC] = "roc",
 230         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 231         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 232         [IIO_EV_TYPE_CHANGE] = "change",
 233 };
 234
 235 static const char * const iio_ev_dir_text[] = {
 236         [IIO_EV_DIR_EITHER] = "either",
 237         [IIO_EV_DIR_RISING] = "rising",
 238         [IIO_EV_DIR_FALLING] = "falling"
 239 };
 240
 241 static const char * const iio_ev_info_text[] = {
 242         [IIO_EV_INFO_ENABLE] = "en",
 243         [IIO_EV_INFO_VALUE] = "value",
 244         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 245         [IIO_EV_INFO_PERIOD] = "period",
 246         [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
 247         [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
 248 };
 249
 250 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
 251 {
 252         return attr->c->event_spec[attr->address & 0xffff].dir;
 253 }
 254
 255 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
 256 {
 257         return attr->c->event_spec[attr->address & 0xffff].type;
 258 }
 259
 260 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
 261 {
 262         return (attr->address >> 16) & 0xffff;
 263 }
 264
 265 static ssize_t iio_ev_state_store(struct device *dev,
 266                                   struct device_attribute *attr,
 267                                   const char *buf,
 268                                   size_t len)
 269 {
 270         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 271         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 272         int ret;
 273         bool val;
 274
 275         ret = strtobool(buf, &val);
 276         if (ret < 0)
 277                 return ret;
 278
 279         ret = indio_dev->info->write_event_config(indio_dev,
 280                 this_attr->c, iio_ev_attr_type(this_attr),
 281                 iio_ev_attr_dir(this_attr), val);
 282
 283         return (ret < 0) ? ret : len;
 284 }
 285
 286 static ssize_t iio_ev_state_show(struct device *dev,
 287                                  struct device_attribute *attr,
 288                                  char *buf)
 289 {
 290         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 291         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 292         int val;
 293
 294         val = indio_dev->info->read_event_config(indio_dev,
 295                 this_attr->c, iio_ev_attr_type(this_attr),
 296                 iio_ev_attr_dir(this_attr));
 297         if (val < 0)
 298                 return val;
 299         else
 300                 return sprintf(buf, "%d\n", val);
 301 }
 302
 303 static ssize_t iio_ev_value_show(struct device *dev,
 304                                  struct device_attribute *attr,
 305                                  char *buf)
 306 {
 307         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 308         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 309         int val, val2, val_arr[2];
 310         int ret;
 311
 312         ret = indio_dev->info->read_event_value(indio_dev,
 313                 this_attr->c, iio_ev_attr_type(this_attr),
 314                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 315                 &val, &val2);
 316         if (ret < 0)
 317                 return ret;
 318         val_arr[0] = val;
 319         val_arr[1] = val2;
 320         return iio_format_value(buf, ret, 2, val_arr);
 321 }
 322
 323 static ssize_t iio_ev_value_store(struct device *dev,
 324                                   struct device_attribute *attr,
 325                                   const char *buf,
 326                                   size_t len)
 327 {
 328         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 329         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 330         int val, val2;
 331         int ret;
 332
 333         if (!indio_dev->info->write_event_value)
 334                 return -EINVAL;
 335
 336         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 337         if (ret)
 338                 return ret;
 339         ret = indio_dev->info->write_event_value(indio_dev,
 340                 this_attr->c, iio_ev_attr_type(this_attr),
 341                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 342                 val, val2);
 343         if (ret < 0)
 344                 return ret;
 345
 346         return len;
 347 }
 348
 349 static int iio_device_add_event(struct iio_dev *indio_dev,
 350         const struct iio_chan_spec *chan, unsigned int spec_index,
 351         enum iio_event_type type, enum iio_event_direction dir,
 352         enum iio_shared_by shared_by, const unsigned long *mask)
 353 {
 354         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 355         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 356         ssize_t (*store)(struct device *, struct device_attribute *,
 357                 const char *, size_t);
 358         unsigned int attrcount = 0;
 359         unsigned int i;
 360         char *postfix;
 361         int ret;
 362
 363         for_each_set_bit(i, mask, sizeof(*mask)*8) {
 364                 if (i >= ARRAY_SIZE(iio_ev_info_text))
 365                         return -EINVAL;
 366                 if (dir != IIO_EV_DIR_NONE)
 367                         postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 368                                         iio_ev_type_text[type],
 369                                         iio_ev_dir_text[dir],
 370                                         iio_ev_info_text[i]);
 371                 else
 372                         postfix = kasprintf(GFP_KERNEL, "%s_%s",
 373                                         iio_ev_type_text[type],
 374                                         iio_ev_info_text[i]);
 375                 if (postfix == NULL)
 376                         return -ENOMEM;
 377
 378                 if (i == IIO_EV_INFO_ENABLE) {
 379                         show = iio_ev_state_show;
 380                         store = iio_ev_state_store;
 381                 } else {
 382                         show = iio_ev_value_show;
 383                         store = iio_ev_value_store;
 384                 }
 385
 386                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 387                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 388                         &iio_dev_opaque->event_interface->dev_attr_list);
 389                 kfree(postfix);
 390
 391                 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
 392                         continue;
 393
 394                 if (ret)
 395                         return ret;
 396
 397                 attrcount++;
 398         }
 399
 400         return attrcount;
 401 }
 402
 403 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 404         struct iio_chan_spec const *chan)
 405 {
 406         int ret = 0, i, attrcount = 0;
 407         enum iio_event_direction dir;
 408         enum iio_event_type type;
 409
 410         for (i = 0; i < chan->num_event_specs; i++) {
 411                 type = chan->event_spec[i].type;
 412                 dir = chan->event_spec[i].dir;
 413
 414                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 415                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 416                 if (ret < 0)
 417                         return ret;
 418                 attrcount += ret;
 419
 420                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 421                         IIO_SHARED_BY_TYPE,
 422                         &chan->event_spec[i].mask_shared_by_type);
 423                 if (ret < 0)
 424                         return ret;
 425                 attrcount += ret;
 426
 427                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 428                         IIO_SHARED_BY_DIR,
 429                         &chan->event_spec[i].mask_shared_by_dir);
 430                 if (ret < 0)
 431                         return ret;
 432                 attrcount += ret;
 433
 434                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 435                         IIO_SHARED_BY_ALL,
 436                         &chan->event_spec[i].mask_shared_by_all);
 437                 if (ret < 0)
 438                         return ret;
 439                 attrcount += ret;
 440         }
 441         ret = attrcount;
 442         return ret;
 443 }
 444
 445 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 446 {
 447         int j, ret, attrcount = 0;
 448
 449         /* Dynamically created from the channels array */
 450         for (j = 0; j < indio_dev->num_channels; j++) {
 451                 ret = iio_device_add_event_sysfs(indio_dev,
 452                                                  &indio_dev->channels[j]);
 453                 if (ret < 0)
 454                         return ret;
 455                 attrcount += ret;
 456         }
 457         return attrcount;
 458 }
 459
 460 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 461 {
 462         int j;
 463
 464         for (j = 0; j < indio_dev->num_channels; j++) {
 465                 if (indio_dev->channels[j].num_event_specs != 0)
 466                         return true;
 467         }
 468         return false;
 469 }
 470
 471 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 472 {
 473         INIT_KFIFO(ev_int->det_events);
 474         init_waitqueue_head(&ev_int->wait);
 475         mutex_init(&ev_int->read_lock);
 476 }
 477
 478 static long iio_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
 479                             unsigned int cmd, unsigned long arg)
 480 {
 481         int __user *ip = (int __user *)arg;
 482         int fd;
 483
 484         if (cmd == IIO_GET_EVENT_FD_IOCTL) {
 485                 fd = iio_event_getfd(indio_dev);
 486                 if (fd < 0)
 487                         return fd;
 488                 if (copy_to_user(ip, &fd, sizeof(fd)))
 489                         return -EFAULT;
 490                 return 0;
 491         }
 492
 493         return IIO_IOCTL_UNHANDLED;
 494 }
 495
 496 static const char *iio_event_group_name = "events";
 497 int iio_device_register_eventset(struct iio_dev *indio_dev)
 498 {
 499         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 500         struct iio_event_interface *ev_int;
 501         struct iio_dev_attr *p;
 502         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 503         struct attribute **attr;
 504
 505         if (!(indio_dev->info->event_attrs ||
 506               iio_check_for_dynamic_events(indio_dev)))
 507                 return 0;
 508
 509         ev_int = kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 510         if (ev_int == NULL)
 511                 return -ENOMEM;
 512
 513         iio_dev_opaque->event_interface = ev_int;
 514
 515         INIT_LIST_HEAD(&ev_int->dev_attr_list);
 516
 517         iio_setup_ev_int(ev_int);
 518         if (indio_dev->info->event_attrs != NULL) {
 519                 attr = indio_dev->info->event_attrs->attrs;
 520                 while (*attr++ != NULL)
 521                         attrcount_orig++;
 522         }
 523         attrcount = attrcount_orig;
 524         if (indio_dev->channels) {
 525                 ret = __iio_add_event_config_attrs(indio_dev);
 526                 if (ret < 0)
 527                         goto error_free_setup_event_lines;
 528                 attrcount += ret;
 529         }
 530
 531         ev_int->group.name = iio_event_group_name;
 532         ev_int->group.attrs = kcalloc(attrcount + 1,
 533                                       sizeof(ev_int->group.attrs[0]),
 534                                       GFP_KERNEL);
 535         if (ev_int->group.attrs == NULL) {
 536                 ret = -ENOMEM;
 537                 goto error_free_setup_event_lines;
 538         }
 539         if (indio_dev->info->event_attrs)
 540                 memcpy(ev_int->group.attrs,
 541                        indio_dev->info->event_attrs->attrs,
 542                        sizeof(ev_int->group.attrs[0]) * attrcount_orig);
 543         attrn = attrcount_orig;
 544         /* Add all elements from the list. */
 545         list_for_each_entry(p, &ev_int->dev_attr_list, l)
 546                 ev_int->group.attrs[attrn++] = &p->dev_attr.attr;
 547         indio_dev->groups[indio_dev->groupcounter++] = &ev_int->group;
 548
 549         ev_int->ioctl_handler.ioctl = iio_event_ioctl;
 550         iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev,
 551                                           &ev_int->ioctl_handler);
 552
 553         return 0;
 554
 555 error_free_setup_event_lines:
 556         iio_free_chan_devattr_list(&ev_int->dev_attr_list);
 557         kfree(ev_int);
 558         iio_dev_opaque->event_interface = NULL;
 559         return ret;
 560 }
 561
 562 /**
 563  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 564  * @indio_dev: The IIO device
 565  *
 566  * Wakes up the event waitqueue used for poll() and blocking read().
 567  * Should usually be called when the device is unregistered.
 568  */
 569 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 570 {
 571         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 572
 573         if (iio_dev_opaque->event_interface == NULL)
 574                 return;
 575         wake_up(&iio_dev_opaque->event_interface->wait);
 576 }
 577
 578 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 579 {
 580         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 581         struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 582
 583         if (ev_int == NULL)
 584                 return;
 585
 586         iio_device_ioctl_handler_unregister(&ev_int->ioctl_handler);
 587         iio_free_chan_devattr_list(&ev_int->dev_attr_list);
 588         kfree(ev_int->group.attrs);
 589         kfree(ev_int);
 590         iio_dev_opaque->event_interface = NULL;
 591 }