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