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         struct mutex            read_lock;
  44 };
  45
  46 /**
  47  * iio_push_event() - try to add event to the list for userspace reading
  48  * @indio_dev:          IIO device structure
  49  * @ev_code:            What event
  50  * @timestamp:          When the event occurred
  51  *
  52  * Note: The caller must make sure that this function is not running
  53  * concurrently for the same indio_dev more than once.
  54  **/
  55 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  56 {
  57         struct iio_event_interface *ev_int = indio_dev->event_interface;
  58         struct iio_event_data ev;
  59         int copied;
  60
  61         /* Does anyone care? */
  62         if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  63
  64                 ev.id = ev_code;
  65                 ev.timestamp = timestamp;
  66
  67                 copied = kfifo_put(&ev_int->det_events, ev);
  68                 if (copied != 0)
  69                         wake_up_poll(&ev_int->wait, POLLIN);
  70         }
  71
  72         return 0;
  73 }
  74 EXPORT_SYMBOL(iio_push_event);
  75
  76 /**
  77  * iio_event_poll() - poll the event queue to find out if it has data
  78  */
  79 static unsigned int iio_event_poll(struct file *filep,
  80                              struct poll_table_struct *wait)
  81 {
  82         struct iio_dev *indio_dev = filep->private_data;
  83         struct iio_event_interface *ev_int = indio_dev->event_interface;
  84         unsigned int events = 0;
  85
  86         if (!indio_dev->info)
  87                 return -ENODEV;
  88
  89         poll_wait(filep, &ev_int->wait, wait);
  90
  91         if (!kfifo_is_empty(&ev_int->det_events))
  92                 events = POLLIN | POLLRDNORM;
  93
  94         return events;
  95 }
  96
  97 static ssize_t iio_event_chrdev_read(struct file *filep,
  98                                      char __user *buf,
  99                                      size_t count,
 100                                      loff_t *f_ps)
 101 {
 102         struct iio_dev *indio_dev = filep->private_data;
 103         struct iio_event_interface *ev_int = indio_dev->event_interface;
 104         unsigned int copied;
 105         int ret;
 106
 107         if (!indio_dev->info)
 108                 return -ENODEV;
 109
 110         if (count < sizeof(struct iio_event_data))
 111                 return -EINVAL;
 112
 113         do {
 114                 if (kfifo_is_empty(&ev_int->det_events)) {
 115                         if (filep->f_flags & O_NONBLOCK)
 116                                 return -EAGAIN;
 117
 118                         ret = wait_event_interruptible(ev_int->wait,
 119                                         !kfifo_is_empty(&ev_int->det_events) ||
 120                                         indio_dev->info == NULL);
 121                         if (ret)
 122                                 return ret;
 123                         if (indio_dev->info == NULL)
 124                                 return -ENODEV;
 125                 }
 126
 127                 if (mutex_lock_interruptible(&ev_int->read_lock))
 128                         return -ERESTARTSYS;
 129                 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 130                 mutex_unlock(&ev_int->read_lock);
 131
 132                 if (ret)
 133                         return ret;
 134
 135                 /*
 136                  * If we couldn't read anything from the fifo (a different
 137                  * thread might have been faster) we either return -EAGAIN if
 138                  * the file descriptor is non-blocking, otherwise we go back to
 139                  * sleep and wait for more data to arrive.
 140                  */
 141                 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
 142                         return -EAGAIN;
 143
 144         } while (copied == 0);
 145
 146         return copied;
 147 }
 148
 149 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 150 {
 151         struct iio_dev *indio_dev = filep->private_data;
 152         struct iio_event_interface *ev_int = indio_dev->event_interface;
 153
 154         clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 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         if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags))
 178                 return -EBUSY;
 179
 180         iio_device_get(indio_dev);
 181
 182         fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
 183                                 indio_dev, O_RDONLY | O_CLOEXEC);
 184         if (fd < 0) {
 185                 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 186                 iio_device_put(indio_dev);
 187         } else {
 188                 kfifo_reset_out(&ev_int->det_events);
 189         }
 190
 191         return fd;
 192 }
 193
 194 static const char * const iio_ev_type_text[] = {
 195         [IIO_EV_TYPE_THRESH] = "thresh",
 196         [IIO_EV_TYPE_MAG] = "mag",
 197         [IIO_EV_TYPE_ROC] = "roc",
 198         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 199         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 200         [IIO_EV_TYPE_CHANGE] = "change",
 201 };
 202
 203 static const char * const iio_ev_dir_text[] = {
 204         [IIO_EV_DIR_EITHER] = "either",
 205         [IIO_EV_DIR_RISING] = "rising",
 206         [IIO_EV_DIR_FALLING] = "falling"
 207 };
 208
 209 static const char * const iio_ev_info_text[] = {
 210         [IIO_EV_INFO_ENABLE] = "en",
 211         [IIO_EV_INFO_VALUE] = "value",
 212         [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
 213         [IIO_EV_INFO_PERIOD] = "period",
 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, val_arr[2];
 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         val_arr[0] = val;
 285         val_arr[1] = val2;
 286         return iio_format_value(buf, ret, 2, val_arr);
 287 }
 288
 289 static ssize_t iio_ev_value_store(struct device *dev,
 290                                   struct device_attribute *attr,
 291                                   const char *buf,
 292                                   size_t len)
 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;
 297         int ret;
 298
 299         if (!indio_dev->info->write_event_value)
 300                 return -EINVAL;
 301
 302         ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
 303         if (ret)
 304                 return ret;
 305         ret = indio_dev->info->write_event_value(indio_dev,
 306                 this_attr->c, iio_ev_attr_type(this_attr),
 307                 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
 308                 val, val2);
 309         if (ret < 0)
 310                 return ret;
 311
 312         return len;
 313 }
 314
 315 static int iio_device_add_event(struct iio_dev *indio_dev,
 316         const struct iio_chan_spec *chan, unsigned int spec_index,
 317         enum iio_event_type type, enum iio_event_direction dir,
 318         enum iio_shared_by shared_by, const unsigned long *mask)
 319 {
 320         ssize_t (*show)(struct device *, struct device_attribute *, char *);
 321         ssize_t (*store)(struct device *, struct device_attribute *,
 322                 const char *, size_t);
 323         unsigned int attrcount = 0;
 324         unsigned int i;
 325         char *postfix;
 326         int ret;
 327
 328         for_each_set_bit(i, mask, sizeof(*mask)*8) {
 329                 if (i >= ARRAY_SIZE(iio_ev_info_text))
 330                         return -EINVAL;
 331                 if (dir != IIO_EV_DIR_NONE)
 332                         postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
 333                                         iio_ev_type_text[type],
 334                                         iio_ev_dir_text[dir],
 335                                         iio_ev_info_text[i]);
 336                 else
 337                         postfix = kasprintf(GFP_KERNEL, "%s_%s",
 338                                         iio_ev_type_text[type],
 339                                         iio_ev_info_text[i]);
 340                 if (postfix == NULL)
 341                         return -ENOMEM;
 342
 343                 if (i == IIO_EV_INFO_ENABLE) {
 344                         show = iio_ev_state_show;
 345                         store = iio_ev_state_store;
 346                 } else {
 347                         show = iio_ev_value_show;
 348                         store = iio_ev_value_store;
 349                 }
 350
 351                 ret = __iio_add_chan_devattr(postfix, chan, show, store,
 352                          (i << 16) | spec_index, shared_by, &indio_dev->dev,
 353                         &indio_dev->event_interface->dev_attr_list);
 354                 kfree(postfix);
 355
 356                 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
 357                         continue;
 358
 359                 if (ret)
 360                         return ret;
 361
 362                 attrcount++;
 363         }
 364
 365         return attrcount;
 366 }
 367
 368 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 369         struct iio_chan_spec const *chan)
 370 {
 371         int ret = 0, i, attrcount = 0;
 372         enum iio_event_direction dir;
 373         enum iio_event_type type;
 374
 375         for (i = 0; i < chan->num_event_specs; i++) {
 376                 type = chan->event_spec[i].type;
 377                 dir = chan->event_spec[i].dir;
 378
 379                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 380                         IIO_SEPARATE, &chan->event_spec[i].mask_separate);
 381                 if (ret < 0)
 382                         return ret;
 383                 attrcount += ret;
 384
 385                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 386                         IIO_SHARED_BY_TYPE,
 387                         &chan->event_spec[i].mask_shared_by_type);
 388                 if (ret < 0)
 389                         return ret;
 390                 attrcount += ret;
 391
 392                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 393                         IIO_SHARED_BY_DIR,
 394                         &chan->event_spec[i].mask_shared_by_dir);
 395                 if (ret < 0)
 396                         return ret;
 397                 attrcount += ret;
 398
 399                 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
 400                         IIO_SHARED_BY_ALL,
 401                         &chan->event_spec[i].mask_shared_by_all);
 402                 if (ret < 0)
 403                         return ret;
 404                 attrcount += ret;
 405         }
 406         ret = attrcount;
 407         return ret;
 408 }
 409
 410 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 411 {
 412         int j, ret, attrcount = 0;
 413
 414         /* Dynamically created from the channels array */
 415         for (j = 0; j < indio_dev->num_channels; j++) {
 416                 ret = iio_device_add_event_sysfs(indio_dev,
 417                                                  &indio_dev->channels[j]);
 418                 if (ret < 0)
 419                         return ret;
 420                 attrcount += ret;
 421         }
 422         return attrcount;
 423 }
 424
 425 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 426 {
 427         int j;
 428
 429         for (j = 0; j < indio_dev->num_channels; j++) {
 430                 if (indio_dev->channels[j].num_event_specs != 0)
 431                         return true;
 432         }
 433         return false;
 434 }
 435
 436 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 437 {
 438         INIT_KFIFO(ev_int->det_events);
 439         init_waitqueue_head(&ev_int->wait);
 440         mutex_init(&ev_int->read_lock);
 441 }
 442
 443 static const char *iio_event_group_name = "events";
 444 int iio_device_register_eventset(struct iio_dev *indio_dev)
 445 {
 446         struct iio_dev_attr *p;
 447         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 448         struct attribute **attr;
 449
 450         if (!(indio_dev->info->event_attrs ||
 451               iio_check_for_dynamic_events(indio_dev)))
 452                 return 0;
 453
 454         indio_dev->event_interface =
 455                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 456         if (indio_dev->event_interface == NULL)
 457                 return -ENOMEM;
 458
 459         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 460
 461         iio_setup_ev_int(indio_dev->event_interface);
 462         if (indio_dev->info->event_attrs != NULL) {
 463                 attr = indio_dev->info->event_attrs->attrs;
 464                 while (*attr++ != NULL)
 465                         attrcount_orig++;
 466         }
 467         attrcount = attrcount_orig;
 468         if (indio_dev->channels) {
 469                 ret = __iio_add_event_config_attrs(indio_dev);
 470                 if (ret < 0)
 471                         goto error_free_setup_event_lines;
 472                 attrcount += ret;
 473         }
 474
 475         indio_dev->event_interface->group.name = iio_event_group_name;
 476         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 477                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 478                                                           GFP_KERNEL);
 479         if (indio_dev->event_interface->group.attrs == NULL) {
 480                 ret = -ENOMEM;
 481                 goto error_free_setup_event_lines;
 482         }
 483         if (indio_dev->info->event_attrs)
 484                 memcpy(indio_dev->event_interface->group.attrs,
 485                        indio_dev->info->event_attrs->attrs,
 486                        sizeof(indio_dev->event_interface->group.attrs[0])
 487                        *attrcount_orig);
 488         attrn = attrcount_orig;
 489         /* Add all elements from the list. */
 490         list_for_each_entry(p,
 491                             &indio_dev->event_interface->dev_attr_list,
 492                             l)
 493                 indio_dev->event_interface->group.attrs[attrn++] =
 494                         &p->dev_attr.attr;
 495         indio_dev->groups[indio_dev->groupcounter++] =
 496                 &indio_dev->event_interface->group;
 497
 498         return 0;
 499
 500 error_free_setup_event_lines:
 501         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 502         kfree(indio_dev->event_interface);
 503         indio_dev->event_interface = NULL;
 504         return ret;
 505 }
 506
 507 /**
 508  * iio_device_wakeup_eventset - Wakes up the event waitqueue
 509  * @indio_dev: The IIO device
 510  *
 511  * Wakes up the event waitqueue used for poll() and blocking read().
 512  * Should usually be called when the device is unregistered.
 513  */
 514 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
 515 {
 516         if (indio_dev->event_interface == NULL)
 517                 return;
 518         wake_up(&indio_dev->event_interface->wait);
 519 }
 520
 521 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 522 {
 523         if (indio_dev->event_interface == NULL)
 524                 return;
 525         iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 526         kfree(indio_dev->event_interface->group.attrs);
 527         kfree(indio_dev->event_interface);
 528 }