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  */
  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 };
  44
  45 /**
  46  * iio_push_event() - try to add event to the list for userspace reading
  47  * @indio_dev:          IIO device structure
  48  * @ev_code:            What event
  49  * @timestamp:          When the event occurred
  50  **/
  51 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  52 {
  53         struct iio_event_interface *ev_int = indio_dev->event_interface;
  54         struct iio_event_data ev;
  55         unsigned long flags;
  56         int copied;
  57
  58         /* Does anyone care? */
  59         spin_lock_irqsave(&ev_int->wait.lock, flags);
  60         if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  61
  62                 ev.id = ev_code;
  63                 ev.timestamp = timestamp;
  64
  65                 copied = kfifo_put(&ev_int->det_events, ev);
  66                 if (copied != 0)
  67                         wake_up_locked_poll(&ev_int->wait, POLLIN);
  68         }
  69         spin_unlock_irqrestore(&ev_int->wait.lock, flags);
  70
  71         return 0;
  72 }
  73 EXPORT_SYMBOL(iio_push_event);
  74
  75 /**
  76  * iio_event_poll() - poll the event queue to find out if it has data
  77  */
  78 static unsigned int iio_event_poll(struct file *filep,
  79                              struct poll_table_struct *wait)
  80 {
  81         struct iio_dev *indio_dev = filep->private_data;
  82         struct iio_event_interface *ev_int = indio_dev->event_interface;
  83         unsigned int events = 0;
  84
  85         if (!indio_dev->info)
  86                 return -ENODEV;
  87
  88         poll_wait(filep, &ev_int->wait, wait);
  89
  90         spin_lock_irq(&ev_int->wait.lock);
  91         if (!kfifo_is_empty(&ev_int->det_events))
  92                 events = POLLIN | POLLRDNORM;
  93         spin_unlock_irq(&ev_int->wait.lock);
  94
  95         return events;
  96 }
  97
  98 static ssize_t iio_event_chrdev_read(struct file *filep,
  99                                      char __user *buf,
 100                                      size_t count,
 101                                      loff_t *f_ps)
 102 {
 103         struct iio_dev *indio_dev = filep->private_data;
 104         struct iio_event_interface *ev_int = indio_dev->event_interface;
 105         unsigned int copied;
 106         int ret;
 107
 108         if (!indio_dev->info)
 109                 return -ENODEV;
 110
 111         if (count < sizeof(struct iio_event_data))
 112                 return -EINVAL;
 113
 114         spin_lock_irq(&ev_int->wait.lock);
 115         if (kfifo_is_empty(&ev_int->det_events)) {
 116                 if (filep->f_flags & O_NONBLOCK) {
 117                         ret = -EAGAIN;
 118                         goto error_unlock;
 119                 }
 120                 /* Blocking on device; waiting for something to be there */
 121                 ret = wait_event_interruptible_locked_irq(ev_int->wait,
 122                                         !kfifo_is_empty(&ev_int->det_events) ||
 123                                         indio_dev->info == NULL);
 124                 if (ret)
 125                         goto error_unlock;
 126                 if (indio_dev->info == NULL) {
 127                         ret = -ENODEV;
 128                         goto error_unlock;
 129                 }
 130                 /* Single access device so no one else can get the data */
 131         }
 132
 133         ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 134
 135 error_unlock:
 136         spin_unlock_irq(&ev_int->wait.lock);
 137
 138         return ret ? ret : copied;
 139 }
 140
 141 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 142 {
 143         struct iio_dev *indio_dev = filep->private_data;
 144         struct iio_event_interface *ev_int = indio_dev->event_interface;
 145
 146         spin_lock_irq(&ev_int->wait.lock);
 147         __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 148         /*
 149          * In order to maintain a clean state for reopening,
 150          * clear out any awaiting events. The mask will prevent
 151          * any new __iio_push_event calls running.
 152          */
 153         kfifo_reset_out(&ev_int->det_events);
 154         spin_unlock_irq(&ev_int->wait.lock);
 155
 156         iio_device_put(indio_dev);
 157
 158         return 0;
 159 }
 160
 161 static const struct file_operations iio_event_chrdev_fileops = {
 162         .read =  iio_event_chrdev_read,
 163         .poll =  iio_event_poll,
 164         .release = iio_event_chrdev_release,
 165         .owner = THIS_MODULE,
 166         .llseek = noop_llseek,
 167 };
 168
 169 int iio_event_getfd(struct iio_dev *indio_dev)
 170 {
 171         struct iio_event_interface *ev_int = indio_dev->event_interface;
 172         int fd;
 173
 174         if (ev_int == NULL)
 175                 return -ENODEV;
 176
 177         spin_lock_irq(&ev_int->wait.lock);
 178         if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 179                 spin_unlock_irq(&ev_int->wait.lock);
 180                 return -EBUSY;
 181         }
 182         spin_unlock_irq(&ev_int->wait.lock);
 183         iio_device_get(indio_dev);
 184
 185         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 186                                 indio_dev, O_RDONLY | O_CLOEXEC);
 187         if (fd < 0) {
 188                 spin_lock_irq(&ev_int->wait.lock);
 189                 __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 190                 spin_unlock_irq(&ev_int->wait.lock);
 191                 iio_device_put(indio_dev);
 192         }
 193         return fd;
 194 }
 195
 196 static const char * const iio_ev_type_text[] = {
 197         [IIO_EV_TYPE_THRESH] = "thresh",
 198         [IIO_EV_TYPE_MAG] = "mag",
 199         [IIO_EV_TYPE_ROC] = "roc",
 200         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 201         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 202 };
 203
 204 static const char * const iio_ev_dir_text[] = {
 205         [IIO_EV_DIR_EITHER] = "either",
 206         [IIO_EV_DIR_RISING] = "rising",
 207         [IIO_EV_DIR_FALLING] = "falling"
 208 };
 209
 210 static const char * const iio_ev_info_text[] = {
 211         [IIO_EV_INFO_ENABLE] = "en",
 212         [IIO_EV_INFO_VALUE] = "value",
 213         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 214 };
 215
 216 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
 217 {
 218         return attr->c->event_spec[attr->address & 0xffff].dir;
 219 }
 220
 221 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
 222 {
 223         return attr->c->event_spec[attr->address & 0xffff].type;
 224 }
 225
 226 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
 227 {
 228         return (attr->address >> 16) & 0xffff;
 229 }
 230
 231 static ssize_t iio_ev_state_store(struct device *dev,
 232                                   struct device_attribute *attr,
 233                                   const char *buf,
 234                                   size_t len)
 235 {
 236         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 237         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 238         int ret;
 239         bool val;
 240
 241         ret = strtobool(buf, &val);
 242         if (ret < 0)
 243                 return ret;
 244
 245         ret = indio_dev->info->write_event_config(indio_dev,
 246                 this_attr->c, iio_ev_attr_type(this_attr),
 247                 iio_ev_attr_dir(this_attr), val);
 248
 249         return (ret < 0) ? ret : len;
 250 }
 251
 252 static ssize_t iio_ev_state_show(struct device *dev,
 253                                  struct device_attribute *attr,
 254                                  char *buf)
 255 {
 256         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 257         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 258         int val;
 259
 260         val = indio_dev->info->read_event_config(indio_dev,
 261                 this_attr->c, iio_ev_attr_type(this_attr),
 262                 iio_ev_attr_dir(this_attr));
 263         if (val < 0)
 264                 return val;
 265         else
 266                 return sprintf(buf, "%d\n", val);
 267 }
 268
 269 static ssize_t iio_ev_value_show(struct device *dev,
 270                                  struct device_attribute *attr,
 271                                  char *buf)
 272 {
 273         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 274         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 275         int val, val2;
 276         int ret;
 277
 278         ret = indio_dev->info->read_event_value(indio_dev,
 279                 this_attr->c, iio_ev_attr_type(this_attr),
 280                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 281                 &val, &val2);
 282         if (ret < 0)
 283                 return ret;
 284         return iio_format_value(buf, ret, val, val2);
 285 }
 286
 287 static ssize_t iio_ev_value_store(struct device *dev,
 288                                   struct device_attribute *attr,
 289                                   const char *buf,
 290                                   size_t len)
 291 {
 292         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 293         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 294         int val, val2;
 295         int ret;
 296
 297         if (!indio_dev->info->write_event_value)
 298                 return -EINVAL;
 299
 300         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 301         if (ret)
 302                 return ret;
 303         ret = indio_dev->info->write_event_value(indio_dev,
 304                 this_attr->c, iio_ev_attr_type(this_attr),
 305                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 306                 val, val2);
 307         if (ret < 0)
 308                 return ret;
 309
 310         return len;
 311 }
 312
 313 static int iio_device_add_event(struct iio_dev *indio_dev,
 314         const struct iio_chan_spec *chan, unsigned int spec_index,
 315         enum iio_event_type type, enum iio_event_direction dir,
 316         enum iio_shared_by shared_by, const unsigned long *mask)
 317 {
 318         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 319         ssize_t (*store)(struct device *, struct device_attribute *,
 320                 const char *, size_t);
 321         unsigned int attrcount = 0;
 322         unsigned int i;
 323         char *postfix;
 324         int ret;
 325
 326         for_each_set_bit(i, mask, sizeof(*mask)) {
 327                 postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 328                                 iio_ev_type_text[type], iio_ev_dir_text[dir],
 329                                 iio_ev_info_text[i]);
 330                 if (postfix == NULL)
 331                         return -ENOMEM;
 332
 333                 if (i == IIO_EV_INFO_ENABLE) {
 334                         show = iio_ev_state_show;
 335                         store = iio_ev_state_store;
 336                 } else {
 337                         show = iio_ev_value_show;
 338                         store = iio_ev_value_store;
 339                 }
 340
 341                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 342                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 343                         &indio_dev->event_interface->dev_attr_list);
 344                 kfree(postfix);
 345
 346                 if (ret)
 347                         return ret;
 348
 349                 attrcount++;
 350         }
 351
 352         return attrcount;
 353 }
 354
 355 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 356         struct iio_chan_spec const *chan)
 357 {
 358         int ret = 0, i, attrcount = 0;
 359         enum iio_event_direction dir;
 360         enum iio_event_type type;
 361
 362         for (i = 0; i < chan->num_event_specs; i++) {
 363                 type = chan->event_spec[i].type;
 364                 dir = chan->event_spec[i].dir;
 365
 366                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 367                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 368                 if (ret < 0)
 369                         goto error_ret;
 370                 attrcount += ret;
 371
 372                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 373                         IIO_SHARED_BY_TYPE,
 374                         &chan->event_spec[i].mask_shared_by_type);
 375                 if (ret < 0)
 376                         goto error_ret;
 377                 attrcount += ret;
 378
 379                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 380                         IIO_SHARED_BY_DIR,
 381                         &chan->event_spec[i].mask_shared_by_dir);
 382                 if (ret < 0)
 383                         goto error_ret;
 384                 attrcount += ret;
 385
 386                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 387                         IIO_SHARED_BY_ALL,
 388                         &chan->event_spec[i].mask_shared_by_all);
 389                 if (ret < 0)
 390                         goto error_ret;
 391                 attrcount += ret;
 392         }
 393         ret = attrcount;
 394 error_ret:
 395         return ret;
 396 }
 397
 398 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 399 {
 400         int j, ret, attrcount = 0;
 401
 402         /* Dynically created from the channels array */
 403         for (j = 0; j < indio_dev->num_channels; j++) {
 404                 ret = iio_device_add_event_sysfs(indio_dev,
 405                                                  &indio_dev->channels[j]);
 406                 if (ret < 0)
 407                         return ret;
 408                 attrcount += ret;
 409         }
 410         return attrcount;
 411 }
 412
 413 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 414 {
 415         int j;
 416
 417         for (j = 0; j < indio_dev->num_channels; j++) {
 418                 if (indio_dev->channels[j].num_event_specs != 0)
 419                         return true;
 420         }
 421         return false;
 422 }
 423
 424 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 425 {
 426         INIT_KFIFO(ev_int->det_events);
 427         init_waitqueue_head(&ev_int->wait);
 428 }
 429
 430 static const char *iio_event_group_name = "events";
 431 int iio_device_register_eventset(struct iio_dev *indio_dev)
 432 {
 433         struct iio_dev_attr *p;
 434         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 435         struct attribute **attr;
 436
 437         if (!(indio_dev->info->event_attrs ||
 438               iio_check_for_dynamic_events(indio_dev)))
 439                 return 0;
 440
 441         indio_dev->event_interface =
 442                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 443         if (indio_dev->event_interface == NULL) {
 444                 ret = -ENOMEM;
 445                 goto error_ret;
 446         }
 447
 448         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 449
 450         iio_setup_ev_int(indio_dev->event_interface);
 451         if (indio_dev->info->event_attrs != NULL) {
 452                 attr = indio_dev->info->event_attrs->attrs;
 453                 while (*attr++ != NULL)
 454                         attrcount_orig++;
 455         }
 456         attrcount = attrcount_orig;
 457         if (indio_dev->channels) {
 458                 ret = __iio_add_event_config_attrs(indio_dev);
 459                 if (ret < 0)
 460                         goto error_free_setup_event_lines;
 461                 attrcount += ret;
 462         }
 463
 464         indio_dev->event_interface->group.name = iio_event_group_name;
 465         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 466                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 467                                                           GFP_KERNEL);
 468         if (indio_dev->event_interface->group.attrs == NULL) {
 469                 ret = -ENOMEM;
 470                 goto error_free_setup_event_lines;
 471         }
 472         if (indio_dev->info->event_attrs)
 473                 memcpy(indio_dev->event_interface->group.attrs,
 474                        indio_dev->info->event_attrs->attrs,
 475                        sizeof(indio_dev->event_interface->group.attrs[0])
 476                        *attrcount_orig);
 477         attrn = attrcount_orig;
 478         /* Add all elements from the list. */
 479         list_for_each_entry(p,
 480                             &indio_dev->event_interface->dev_attr_list,
 481                             l)
 482                 indio_dev->event_interface->group.attrs[attrn++] =
 483                         &p->dev_attr.attr;
 484         indio_dev->groups[indio_dev->groupcounter++] =
 485                 &indio_dev->event_interface->group;
 486
 487         return 0;
 488
 489 error_free_setup_event_lines:
 490         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 491         kfree(indio_dev->event_interface);
 492 error_ret:
 493
 494         return ret;
 495 }
 496
 497 /**
 498  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 499  * @indio_dev: The IIO device
 500  *
 501  * Wakes up the event waitqueue used for poll() and blocking read().
 502  * Should usually be called when the device is unregistered.
 503  */
 504 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 505 {
 506         if (indio_dev->event_interface == NULL)
 507                 return;
 508         wake_up(&indio_dev->event_interface->wait);
 509 }
 510
 511 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 512 {
 513         if (indio_dev->event_interface == NULL)
 514                 return;
 515         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 516         kfree(indio_dev->event_interface->group.attrs);
 517         kfree(indio_dev->event_interface);
 518 }