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