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