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 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  46 {
  47         struct iio_event_interface *ev_int = indio_dev->event_interface;
  48         struct iio_event_data ev;
  49         int copied;
  50
  51         /* Does anyone care? */
  52         spin_lock(&ev_int->wait.lock);
  53         if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  54
  55                 ev.id = ev_code;
  56                 ev.timestamp = timestamp;
  57
  58                 copied = kfifo_put(&ev_int->det_events, &ev);
  59                 if (copied != 0)
  60                         wake_up_locked_poll(&ev_int->wait, POLLIN);
  61         }
  62         spin_unlock(&ev_int->wait.lock);
  63
  64         return 0;
  65 }
  66 EXPORT_SYMBOL(iio_push_event);
  67
  68 /**
  69  * iio_event_poll() - poll the event queue to find out if it has data
  70  */
  71 static unsigned int iio_event_poll(struct file *filep,
  72                              struct poll_table_struct *wait)
  73 {
  74         struct iio_event_interface *ev_int = filep->private_data;
  75         unsigned int events = 0;
  76
  77         poll_wait(filep, &ev_int->wait, wait);
  78
  79         spin_lock(&ev_int->wait.lock);
  80         if (!kfifo_is_empty(&ev_int->det_events))
  81                 events = POLLIN | POLLRDNORM;
  82         spin_unlock(&ev_int->wait.lock);
  83
  84         return events;
  85 }
  86
  87 static ssize_t iio_event_chrdev_read(struct file *filep,
  88                                      char __user *buf,
  89                                      size_t count,
  90                                      loff_t *f_ps)
  91 {
  92         struct iio_event_interface *ev_int = filep->private_data;
  93         unsigned int copied;
  94         int ret;
  95
  96         if (count < sizeof(struct iio_event_data))
  97                 return -EINVAL;
  98
  99         spin_lock(&ev_int->wait.lock);
 100         if (kfifo_is_empty(&ev_int->det_events)) {
 101                 if (filep->f_flags & O_NONBLOCK) {
 102                         ret = -EAGAIN;
 103                         goto error_unlock;
 104                 }
 105                 /* Blocking on device; waiting for something to be there */
 106                 ret = wait_event_interruptible_locked(ev_int->wait,
 107                                         !kfifo_is_empty(&ev_int->det_events));
 108                 if (ret)
 109                         goto error_unlock;
 110                 /* Single access device so no one else can get the data */
 111         }
 112
 113         ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 114
 115 error_unlock:
 116         spin_unlock(&ev_int->wait.lock);
 117
 118         return ret ? ret : copied;
 119 }
 120
 121 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 122 {
 123         struct iio_event_interface *ev_int = filep->private_data;
 124
 125         spin_lock(&ev_int->wait.lock);
 126         __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 127         /*
 128          * In order to maintain a clean state for reopening,
 129          * clear out any awaiting events. The mask will prevent
 130          * any new __iio_push_event calls running.
 131          */
 132         kfifo_reset_out(&ev_int->det_events);
 133         spin_unlock(&ev_int->wait.lock);
 134
 135         return 0;
 136 }
 137
 138 static const struct file_operations iio_event_chrdev_fileops = {
 139         .read =  iio_event_chrdev_read,
 140         .poll =  iio_event_poll,
 141         .release = iio_event_chrdev_release,
 142         .owner = THIS_MODULE,
 143         .llseek = noop_llseek,
 144 };
 145
 146 int iio_event_getfd(struct iio_dev *indio_dev)
 147 {
 148         struct iio_event_interface *ev_int = indio_dev->event_interface;
 149         int fd;
 150
 151         if (ev_int == NULL)
 152                 return -ENODEV;
 153
 154         spin_lock(&ev_int->wait.lock);
 155         if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 156                 spin_unlock(&ev_int->wait.lock);
 157                 return -EBUSY;
 158         }
 159         spin_unlock(&ev_int->wait.lock);
 160         fd = anon_inode_getfd("iio:event",
 161                                 &iio_event_chrdev_fileops, ev_int, O_RDONLY);
 162         if (fd < 0) {
 163                 spin_lock(&ev_int->wait.lock);
 164                 __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 165                 spin_unlock(&ev_int->wait.lock);
 166         }
 167         return fd;
 168 }
 169
 170 static const char * const iio_ev_type_text[] = {
 171         [IIO_EV_TYPE_THRESH] = "thresh",
 172         [IIO_EV_TYPE_MAG] = "mag",
 173         [IIO_EV_TYPE_ROC] = "roc",
 174         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 175         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 176 };
 177
 178 static const char * const iio_ev_dir_text[] = {
 179         [IIO_EV_DIR_EITHER] = "either",
 180         [IIO_EV_DIR_RISING] = "rising",
 181         [IIO_EV_DIR_FALLING] = "falling"
 182 };
 183
 184 static ssize_t iio_ev_state_store(struct device *dev,
 185                                   struct device_attribute *attr,
 186                                   const char *buf,
 187                                   size_t len)
 188 {
 189         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 190         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 191         int ret;
 192         bool val;
 193
 194         ret = strtobool(buf, &val);
 195         if (ret < 0)
 196                 return ret;
 197
 198         ret = indio_dev->info->write_event_config(indio_dev,
 199                                                   this_attr->address,
 200                                                   val);
 201         return (ret < 0) ? ret : len;
 202 }
 203
 204 static ssize_t iio_ev_state_show(struct device *dev,
 205                                  struct device_attribute *attr,
 206                                  char *buf)
 207 {
 208         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 209         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 210         int val = indio_dev->info->read_event_config(indio_dev,
 211                                                      this_attr->address);
 212
 213         if (val < 0)
 214                 return val;
 215         else
 216                 return sprintf(buf, "%d\n", val);
 217 }
 218
 219 static ssize_t iio_ev_value_show(struct device *dev,
 220                                  struct device_attribute *attr,
 221                                  char *buf)
 222 {
 223         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 224         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 225         int val, ret;
 226
 227         ret = indio_dev->info->read_event_value(indio_dev,
 228                                                 this_attr->address, &val);
 229         if (ret < 0)
 230                 return ret;
 231
 232         return sprintf(buf, "%d\n", val);
 233 }
 234
 235 static ssize_t iio_ev_value_store(struct device *dev,
 236                                   struct device_attribute *attr,
 237                                   const char *buf,
 238                                   size_t len)
 239 {
 240         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 241         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 242         unsigned long val;
 243         int ret;
 244
 245         if (!indio_dev->info->write_event_value)
 246                 return -EINVAL;
 247
 248         ret = strict_strtoul(buf, 10, &val);
 249         if (ret)
 250                 return ret;
 251
 252         ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
 253                                                  val);
 254         if (ret < 0)
 255                 return ret;
 256
 257         return len;
 258 }
 259
 260 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 261                                       struct iio_chan_spec const *chan)
 262 {
 263         int ret = 0, i, attrcount = 0;
 264         u64 mask = 0;
 265         char *postfix;
 266         if (!chan->event_mask)
 267                 return 0;
 268
 269         for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
 270                 postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
 271                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 272                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 273                 if (postfix == NULL) {
 274                         ret = -ENOMEM;
 275                         goto error_ret;
 276                 }
 277                 if (chan->modified)
 278                         mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel,
 279                                                   i/IIO_EV_DIR_MAX,
 280                                                   i%IIO_EV_DIR_MAX);
 281                 else if (chan->differential)
 282                         mask = IIO_EVENT_CODE(chan->type,
 283                                               0, 0,
 284                                               i%IIO_EV_DIR_MAX,
 285                                               i/IIO_EV_DIR_MAX,
 286                                               0,
 287                                               chan->channel,
 288                                               chan->channel2);
 289                 else
 290                         mask = IIO_UNMOD_EVENT_CODE(chan->type,
 291                                                     chan->channel,
 292                                                     i/IIO_EV_DIR_MAX,
 293                                                     i%IIO_EV_DIR_MAX);
 294
 295                 ret = __iio_add_chan_devattr(postfix,
 296                                              chan,
 297                                              &iio_ev_state_show,
 298                                              iio_ev_state_store,
 299                                              mask,
 300                                              0,
 301                                              &indio_dev->dev,
 302                                              &indio_dev->event_interface->
 303                                              dev_attr_list);
 304                 kfree(postfix);
 305                 if (ret)
 306                         goto error_ret;
 307                 attrcount++;
 308                 postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
 309                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 310                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 311                 if (postfix == NULL) {
 312                         ret = -ENOMEM;
 313                         goto error_ret;
 314                 }
 315                 ret = __iio_add_chan_devattr(postfix, chan,
 316                                              iio_ev_value_show,
 317                                              iio_ev_value_store,
 318                                              mask,
 319                                              0,
 320                                              &indio_dev->dev,
 321                                              &indio_dev->event_interface->
 322                                              dev_attr_list);
 323                 kfree(postfix);
 324                 if (ret)
 325                         goto error_ret;
 326                 attrcount++;
 327         }
 328         ret = attrcount;
 329 error_ret:
 330         return ret;
 331 }
 332
 333 static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
 334 {
 335         struct iio_dev_attr *p, *n;
 336         list_for_each_entry_safe(p, n,
 337                                  &indio_dev->event_interface->
 338                                  dev_attr_list, l) {
 339                 kfree(p->dev_attr.attr.name);
 340                 kfree(p);
 341         }
 342 }
 343
 344 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 345 {
 346         int j, ret, attrcount = 0;
 347
 348         /* Dynically created from the channels array */
 349         for (j = 0; j < indio_dev->num_channels; j++) {
 350                 ret = iio_device_add_event_sysfs(indio_dev,
 351                                                  &indio_dev->channels[j]);
 352                 if (ret < 0)
 353                         goto error_clear_attrs;
 354                 attrcount += ret;
 355         }
 356         return attrcount;
 357
 358 error_clear_attrs:
 359         __iio_remove_event_config_attrs(indio_dev);
 360
 361         return ret;
 362 }
 363
 364 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 365 {
 366         int j;
 367
 368         for (j = 0; j < indio_dev->num_channels; j++)
 369                 if (indio_dev->channels[j].event_mask != 0)
 370                         return true;
 371         return false;
 372 }
 373
 374 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 375 {
 376         INIT_KFIFO(ev_int->det_events);
 377         init_waitqueue_head(&ev_int->wait);
 378 }
 379
 380 static const char *iio_event_group_name = "events";
 381 int iio_device_register_eventset(struct iio_dev *indio_dev)
 382 {
 383         struct iio_dev_attr *p;
 384         int ret = 0, attrcount_orig = 0, attrcount, attrn;
 385         struct attribute **attr;
 386
 387         if (!(indio_dev->info->event_attrs ||
 388               iio_check_for_dynamic_events(indio_dev)))
 389                 return 0;
 390
 391         indio_dev->event_interface =
 392                 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 393         if (indio_dev->event_interface == NULL) {
 394                 ret = -ENOMEM;
 395                 goto error_ret;
 396         }
 397
 398         INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 399
 400         iio_setup_ev_int(indio_dev->event_interface);
 401         if (indio_dev->info->event_attrs != NULL) {
 402                 attr = indio_dev->info->event_attrs->attrs;
 403                 while (*attr++ != NULL)
 404                         attrcount_orig++;
 405         }
 406         attrcount = attrcount_orig;
 407         if (indio_dev->channels) {
 408                 ret = __iio_add_event_config_attrs(indio_dev);
 409                 if (ret < 0)
 410                         goto error_free_setup_event_lines;
 411                 attrcount += ret;
 412         }
 413
 414         indio_dev->event_interface->group.name = iio_event_group_name;
 415         indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 416                                                           sizeof(indio_dev->event_interface->group.attrs[0]),
 417                                                           GFP_KERNEL);
 418         if (indio_dev->event_interface->group.attrs == NULL) {
 419                 ret = -ENOMEM;
 420                 goto error_free_setup_event_lines;
 421         }
 422         if (indio_dev->info->event_attrs)
 423                 memcpy(indio_dev->event_interface->group.attrs,
 424                        indio_dev->info->event_attrs->attrs,
 425                        sizeof(indio_dev->event_interface->group.attrs[0])
 426                        *attrcount_orig);
 427         attrn = attrcount_orig;
 428         /* Add all elements from the list. */
 429         list_for_each_entry(p,
 430                             &indio_dev->event_interface->dev_attr_list,
 431                             l)
 432                 indio_dev->event_interface->group.attrs[attrn++] =
 433                         &p->dev_attr.attr;
 434         indio_dev->groups[indio_dev->groupcounter++] =
 435                 &indio_dev->event_interface->group;
 436
 437         return 0;
 438
 439 error_free_setup_event_lines:
 440         __iio_remove_event_config_attrs(indio_dev);
 441         kfree(indio_dev->event_interface);
 442 error_ret:
 443
 444         return ret;
 445 }
 446
 447 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 448 {
 449         if (indio_dev->event_interface == NULL)
 450                 return;
 451         __iio_remove_event_config_attrs(indio_dev);
 452         kfree(indio_dev->event_interface->group.attrs);
 453         kfree(indio_dev->event_interface);
 454 }