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 "iio_core.h"
  22 #include <linux/iio/sysfs.h>
  23 #include <linux/iio/events.h>
  24
  25 /**
  26  * struct iio_event_interface - chrdev interface for an event line
  27  * @wait:               wait queue to allow blocking reads of events
  28  * @det_events:         list of detected events
  29  * @dev_attr_list:      list of event interface sysfs attribute
  30  * @flags:              file operations related flags including busy flag.
  31  * @group:              event interface sysfs attribute group
  32  * @read_lock:          lock to protect kfifo read operations
  33  */
  34 struct iio_event_interface {
  35         wait_queue_head_t       wait;
  36         DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  37
  38         struct list_head        dev_attr_list;
  39         unsigned long           flags;
  40         struct attribute_group  group;
  41         struct mutex            read_lock;
  42 };
  43
  44 bool iio_event_enabled(const struct iio_event_interface *ev_int)
  45 {
  46         return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
  47 }
  48
  49 /**
  50  * iio_push_event() - try to add event to the list for userspace reading
  51  * @indio_dev:          IIO device structure
  52  * @ev_code:            What event
  53  * @timestamp:          When the event occurred
  54  *
  55  * Note: The caller must make sure that this function is not running
  56  * concurrently for the same indio_dev more than once.
  57  *
  58  * This function may be safely used as soon as a valid reference to iio_dev has
  59  * been obtained via iio_device_alloc(), but any events that are submitted
  60  * before iio_device_register() has successfully completed will be silently
  61  * discarded.
  62  **/
  63 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  64 {
  65         struct iio_event_interface *ev_int = indio_dev->event_interface;
  66         struct iio_event_data ev;
  67         int copied;
  68
  69         if (!ev_int)
  70                 return 0;
  71
  72         /* Does anyone care? */
  73         if (iio_event_enabled(ev_int)) {
  74
  75                 ev.id = ev_code;
  76                 ev.timestamp = timestamp;
  77
  78                 copied = kfifo_put(&ev_int->det_events, ev);
  79                 if (copied != 0)
  80                         wake_up_poll(&ev_int->wait, EPOLLIN);
  81         }
  82
  83         return 0;
  84 }
  85 EXPORT_SYMBOL(iio_push_event);
  86
  87 /**
  88  * iio_event_poll() - poll the event queue to find out if it has data
  89  * @filep:      File structure pointer to identify the device
  90  * @wait:       Poll table pointer to add the wait queue on
  91  *
  92  * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
  93  *         or a negative error code on failure
  94  */
  95 static __poll_t iio_event_poll(struct file *filep,
  96                              struct poll_table_struct *wait)
  97 {
  98         struct iio_dev *indio_dev = filep->private_data;
  99         struct iio_event_interface *ev_int = indio_dev->event_interface;
 100         __poll_t events = 0;
 101
 102         if (!indio_dev->info)
 103                 return events;
 104
 105         poll_wait(filep, &ev_int->wait, wait);
 106
 107         if (!kfifo_is_empty(&ev_int->det_events))
 108                 events = EPOLLIN | EPOLLRDNORM;
 109
 110         return events;
 111 }
 112
 113 static ssize_t iio_event_chrdev_read(struct file *filep,
 114                                      char __user *buf,
 115                                      size_t count,
 116                                      loff_t *f_ps)
 117 {
 118         struct iio_dev *indio_dev = filep->private_data;
 119         struct iio_event_interface *ev_int = indio_dev->event_interface;
 120         unsigned int copied;
 121         int ret;
 122
 123         if (!indio_dev->info)
 124                 return -ENODEV;
 125
 126         if (count < sizeof(struct iio_event_data))
 127                 return -EINVAL;
 128
 129         do {
 130                 if (kfifo_is_empty(&ev_int->det_events)) {
 131                         if (filep->f_flags & O_NONBLOCK)
 132                                 return -EAGAIN;
 133
 134                         ret = wait_event_interruptible(ev_int->wait,
 135                                         !kfifo_is_empty(&ev_int->det_events) ||
 136                                         indio_dev->info == NULL);
 137                         if (ret)
 138                                 return ret;
 139                         if (indio_dev->info == NULL)
 140                                 return -ENODEV;
 141                 }
 142
 143                 if (mutex_lock_interruptible(&ev_int->read_lock))
 144                         return -ERESTARTSYS;
 145                 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 146                 mutex_unlock(&ev_int->read_lock);
 147
 148                 if (ret)
 149                         return ret;
 150
 151                 /*
 152                  * If we couldn't read anything from the fifo (a different
 153                  * thread might have been faster) we either return -EAGAIN if
 154                  * the file descriptor is non-blocking, otherwise we go back to
 155                  * sleep and wait for more data to arrive.
 156                  */
 157                 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
 158                         return -EAGAIN;
 159
 160         } while (copied == 0);
 161
 162         return copied;
 163 }
 164
 165 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 166 {
 167         struct iio_dev *indio_dev = filep->private_data;
 168         struct iio_event_interface *ev_int = indio_dev->event_interface;
 169
 170         clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 171
 172         iio_device_put(indio_dev);
 173
 174         return 0;
 175 }
 176
 177 static const struct file_operations iio_event_chrdev_fileops = {
 178         .read =  iio_event_chrdev_read,
 179         .poll =  iio_event_poll,
 180         .release = iio_event_chrdev_release,
 181         .owner = THIS_MODULE,
 182         .llseek = noop_llseek,
 183 };
 184
 185 int iio_event_getfd(struct iio_dev *indio_dev)
 186 {
 187         struct iio_event_interface *ev_int = indio_dev->event_interface;
 188         int fd;
 189
 190         if (ev_int == NULL)
 191                 return -ENODEV;
 192
 193         fd = mutex_lock_interruptible(&indio_dev->mlock);
 194         if (fd)
 195                 return fd;
 196
 197         if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 198                 fd = -EBUSY;
 199                 goto unlock;
 200         }
 201
 202         iio_device_get(indio_dev);
 203
 204         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 205                                 indio_dev, O_RDONLY | O_CLOEXEC);
 206         if (fd < 0) {
 207                 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 208                 iio_device_put(indio_dev);
 209         } else {
 210                 kfifo_reset_out(&ev_int->det_events);
 211         }
 212
 213 unlock:
 214         mutex_unlock(&indio_dev->mlock);
 215         return fd;
 216 }
 217
 218 static const char * const iio_ev_type_text[] = {
 219         [IIO_EV_TYPE_THRESH] = "thresh",
 220         [IIO_EV_TYPE_MAG] = "mag",
 221         [IIO_EV_TYPE_ROC] = "roc",
 222         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 223         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 224         [IIO_EV_TYPE_CHANGE] = "change",
 225 };
 226
 227 static const char * const iio_ev_dir_text[] = {
 228         [IIO_EV_DIR_EITHER] = "either",
 229         [IIO_EV_DIR_RISING] = "rising",
 230         [IIO_EV_DIR_FALLING] = "falling"
 231 };
 232
 233 static const char * const iio_ev_info_text[] = {
 234         [IIO_EV_INFO_ENABLE] = "en",
 235         [IIO_EV_INFO_VALUE] = "value",
 236         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 237         [IIO_EV_INFO_PERIOD] = "period",
 238         [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
 239         [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
 240 };
 241
 242 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
 243 {
 244         return attr->c->event_spec[attr->address & 0xffff].dir;
 245 }
 246
 247 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
 248 {
 249         return attr->c->event_spec[attr->address & 0xffff].type;
 250 }
 251
 252 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
 253 {
 254         return (attr->address >> 16) & 0xffff;
 255 }
 256
 257 static ssize_t iio_ev_state_store(struct device *dev,
 258                                   struct device_attribute *attr,
 259                                   const char *buf,
 260                                   size_t len)
 261 {
 262         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 263         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 264         int ret;
 265         bool val;
 266
 267         ret = strtobool(buf, &val);
 268         if (ret < 0)
 269                 return ret;
 270
 271         ret = indio_dev->info->write_event_config(indio_dev,
 272                 this_attr->c, iio_ev_attr_type(this_attr),
 273                 iio_ev_attr_dir(this_attr), val);
 274
 275         return (ret < 0) ? ret : len;
 276 }
 277
 278 static ssize_t iio_ev_state_show(struct device *dev,
 279                                  struct device_attribute *attr,
 280                                  char *buf)
 281 {
 282         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 283         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 284         int val;
 285
 286         val = indio_dev->info->read_event_config(indio_dev,
 287                 this_attr->c, iio_ev_attr_type(this_attr),
 288                 iio_ev_attr_dir(this_attr));
 289         if (val < 0)
 290                 return val;
 291         else
 292                 return sprintf(buf, "%d\n", val);
 293 }
 294
 295 static ssize_t iio_ev_value_show(struct device *dev,
 296                                  struct device_attribute *attr,
 297                                  char *buf)
 298 {
 299         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 300         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 301         int val, val2, val_arr[2];
 302         int ret;
 303
 304         ret = indio_dev->info->read_event_value(indio_dev,
 305                 this_attr->c, iio_ev_attr_type(this_attr),
 306                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 307                 &val, &val2);
 308         if (ret < 0)
 309                 return ret;
 310         val_arr[0] = val;
 311         val_arr[1] = val2;
 312         return iio_format_value(buf, ret, 2, val_arr);
 313 }
 314
 315 static ssize_t iio_ev_value_store(struct device *dev,
 316                                   struct device_attribute *attr,
 317                                   const char *buf,
 318                                   size_t len)
 319 {
 320         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 321         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 322         int val, val2;
 323         int ret;
 324
 325         if (!indio_dev->info->write_event_value)
 326                 return -EINVAL;
 327
 328         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 329         if (ret)
 330                 return ret;
 331         ret = indio_dev->info->write_event_value(indio_dev,
 332                 this_attr->c, iio_ev_attr_type(this_attr),
 333                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 334                 val, val2);
 335         if (ret < 0)
 336                 return ret;
 337
 338         return len;
 339 }
 340
 341 static int iio_device_add_event(struct iio_dev *indio_dev,
 342         const struct iio_chan_spec *chan, unsigned int spec_index,
 343         enum iio_event_type type, enum iio_event_direction dir,
 344         enum iio_shared_by shared_by, const unsigned long *mask)
 345 {
 346         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 347         ssize_t (*store)(struct device *, struct device_attribute *,
 348                 const char *, size_t);
 349         unsigned int attrcount = 0;
 350         unsigned int i;
 351         char *postfix;
 352         int ret;
 353
 354         for_each_set_bit(i, mask, sizeof(*mask)*8) {
 355                 if (i >= ARRAY_SIZE(iio_ev_info_text))
 356                         return -EINVAL;
 357                 if (dir != IIO_EV_DIR_NONE)
 358                         postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 359                                         iio_ev_type_text[type],
 360                                         iio_ev_dir_text[dir],
 361                                         iio_ev_info_text[i]);
 362                 else
 363                         postfix = kasprintf(GFP_KERNEL, "%s_%s",
 364                                         iio_ev_type_text[type],
 365                                         iio_ev_info_text[i]);
 366                 if (postfix == NULL)
 367                         return -ENOMEM;
 368
 369                 if (i == IIO_EV_INFO_ENABLE) {
 370                         show = iio_ev_state_show;
 371                         store = iio_ev_state_store;
 372                 } else {
 373                         show = iio_ev_value_show;
 374                         store = iio_ev_value_store;
 375                 }
 376
 377                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 378                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 379                         &indio_dev->event_interface->dev_attr_list);
 380                 kfree(postfix);
 381
 382                 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
 383                         continue;
 384
 385                 if (ret)
 386                         return ret;
 387
 388                 attrcount++;
 389         }
 390
 391         return attrcount;
 392 }
 393
 394 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 395         struct iio_chan_spec const *chan)
 396 {
 397         int ret = 0, i, attrcount = 0;
 398         enum iio_event_direction dir;
 399         enum iio_event_type type;
 400
 401         for (i = 0; i < chan->num_event_specs; i++) {
 402                 type = chan->event_spec[i].type;
 403                 dir = chan->event_spec[i].dir;
 404
 405                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 406                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 407                 if (ret < 0)
 408                         return ret;
 409                 attrcount += ret;
 410
 411                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 412                         IIO_SHARED_BY_TYPE,
 413                         &chan->event_spec[i].mask_shared_by_type);
 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_DIR,
 420                         &chan->event_spec[i].mask_shared_by_dir);
 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_ALL,
 427                         &chan->event_spec[i].mask_shared_by_all);
 428                 if (ret < 0)
 429                         return ret;
 430                 attrcount += ret;
 431         }
 432         ret = attrcount;
 433         return ret;
 434 }
 435
 436 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 437 {
 438         int j, ret, attrcount = 0;
 439
 440         /* Dynamically created from the channels array */
 441         for (j = 0; j < indio_dev->num_channels; j++) {
 442                 ret = iio_device_add_event_sysfs(indio_dev,
 443                                                  &indio_dev->channels[j]);
 444                 if (ret < 0)
 445                         return ret;
 446                 attrcount += ret;
 447         }
 448         return attrcount;
 449 }
 450
 451 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 452 {
 453         int j;
 454
 455         for (j = 0; j < indio_dev->num_channels; j++) {
 456                 if (indio_dev->channels[j].num_event_specs != 0)
 457                         return true;
 458         }
 459         return false;
 460 }
 461
 462 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 463 {
 464         INIT_KFIFO(ev_int->det_events);
 465         init_waitqueue_head(&ev_int->wait);
 466         mutex_init(&ev_int->read_lock);
 467 }
 468
 469 static const char *iio_event_group_name = "events";
 470 int iio_device_register_eventset(struct iio_dev *indio_dev)
 471 {
 472         struct iio_dev_attr *p;
 473         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 474         struct attribute **attr;
 475
 476         if (!(indio_dev->info->event_attrs ||
 477               iio_check_for_dynamic_events(indio_dev)))
 478                 return 0;
 479
 480         indio_dev->event_interface =
 481                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 482         if (indio_dev->event_interface == NULL)
 483                 return -ENOMEM;
 484
 485         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 486
 487         iio_setup_ev_int(indio_dev->event_interface);
 488         if (indio_dev->info->event_attrs != NULL) {
 489                 attr = indio_dev->info->event_attrs->attrs;
 490                 while (*attr++ != NULL)
 491                         attrcount_orig++;
 492         }
 493         attrcount = attrcount_orig;
 494         if (indio_dev->channels) {
 495                 ret = __iio_add_event_config_attrs(indio_dev);
 496                 if (ret < 0)
 497                         goto error_free_setup_event_lines;
 498                 attrcount += ret;
 499         }
 500
 501         indio_dev->event_interface->group.name = iio_event_group_name;
 502         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 503                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 504                                                           GFP_KERNEL);
 505         if (indio_dev->event_interface->group.attrs == NULL) {
 506                 ret = -ENOMEM;
 507                 goto error_free_setup_event_lines;
 508         }
 509         if (indio_dev->info->event_attrs)
 510                 memcpy(indio_dev->event_interface->group.attrs,
 511                        indio_dev->info->event_attrs->attrs,
 512                        sizeof(indio_dev->event_interface->group.attrs[0])
 513                        *attrcount_orig);
 514         attrn = attrcount_orig;
 515         /* Add all elements from the list. */
 516         list_for_each_entry(p,
 517                             &indio_dev->event_interface->dev_attr_list,
 518                             l)
 519                 indio_dev->event_interface->group.attrs[attrn++] =
 520                         &p->dev_attr.attr;
 521         indio_dev->groups[indio_dev->groupcounter++] =
 522                 &indio_dev->event_interface->group;
 523
 524         return 0;
 525
 526 error_free_setup_event_lines:
 527         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 528         kfree(indio_dev->event_interface);
 529         indio_dev->event_interface = NULL;
 530         return ret;
 531 }
 532
 533 /**
 534  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 535  * @indio_dev: The IIO device
 536  *
 537  * Wakes up the event waitqueue used for poll() and blocking read().
 538  * Should usually be called when the device is unregistered.
 539  */
 540 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 541 {
 542         if (indio_dev->event_interface == NULL)
 543                 return;
 544         wake_up(&indio_dev->event_interface->wait);
 545 }
 546
 547 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 548 {
 549         if (indio_dev->event_interface == NULL)
 550                 return;
 551         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 552         kfree(indio_dev->event_interface->group.attrs);
 553         kfree(indio_dev->event_interface);
 554 }