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         struct mutex            read_lock;
  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 };
  45
  46 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  47 {
  48         struct iio_event_interface *ev_int = indio_dev->event_interface;
  49         struct iio_event_data ev;
  50         unsigned long flags;
  51         int copied;
  52
  53         /* Does anyone care? */
  54         spin_lock_irqsave(&ev_int->wait.lock, flags);
  55         if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  56
  57                 ev.id = ev_code;
  58                 ev.timestamp = timestamp;
  59
  60                 copied = kfifo_put(&ev_int->det_events, &ev);
  61                 if (copied != 0)
  62                         wake_up_locked_poll(&ev_int->wait, POLLIN);
  63         }
  64         spin_unlock_irqrestore(&ev_int->wait.lock, flags);
  65
  66         return 0;
  67 }
  68 EXPORT_SYMBOL(iio_push_event);
  69
  70 /**
  71  * iio_event_poll() - poll the event queue to find out if it has data
  72  */
  73 static unsigned int iio_event_poll(struct file *filep,
  74                              struct poll_table_struct *wait)
  75 {
  76         struct iio_event_interface *ev_int = filep->private_data;
  77         unsigned int events = 0;
  78
  79         poll_wait(filep, &ev_int->wait, wait);
  80
  81         spin_lock_irq(&ev_int->wait.lock);
  82         if (!kfifo_is_empty(&ev_int->det_events))
  83                 events = POLLIN | POLLRDNORM;
  84         spin_unlock_irq(&ev_int->wait.lock);
  85
  86         return events;
  87 }
  88
  89 static ssize_t iio_event_chrdev_read(struct file *filep,
  90                                      char __user *buf,
  91                                      size_t count,
  92                                      loff_t *f_ps)
  93 {
  94         struct iio_event_interface *ev_int = filep->private_data;
  95         unsigned int copied;
  96         int ret;
  97
  98         if (count < sizeof(struct iio_event_data))
  99                 return -EINVAL;
 100
 101         if (mutex_lock_interruptible(&ev_int->read_lock))
 102                 return -ERESTARTSYS;
 103
 104         if (kfifo_is_empty(&ev_int->det_events)) {
 105                 if (filep->f_flags & O_NONBLOCK) {
 106                         ret = -EAGAIN;
 107                         goto error_unlock;
 108                 }
 109                 /* Blocking on device; waiting for something to be there */
 110                 ret = wait_event_interruptible(ev_int->wait,
 111                                         !kfifo_is_empty(&ev_int->det_events));
 112                 if (ret)
 113                         goto error_unlock;
 114                 /* Single access device so no one else can get the data */
 115         }
 116
 117         ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 118
 119 error_unlock:
 120         mutex_unlock(&ev_int->read_lock);
 121
 122         return ret ? ret : copied;
 123 }
 124
 125 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 126 {
 127         struct iio_event_interface *ev_int = filep->private_data;
 128
 129         spin_lock_irq(&ev_int->wait.lock);
 130         __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 131         /*
 132          * In order to maintain a clean state for reopening,
 133          * clear out any awaiting events. The mask will prevent
 134          * any new __iio_push_event calls running.
 135          */
 136         kfifo_reset_out(&ev_int->det_events);
 137         spin_unlock_irq(&ev_int->wait.lock);
 138
 139         return 0;
 140 }
 141
 142 static const struct file_operations iio_event_chrdev_fileops = {
 143         .read =  iio_event_chrdev_read,
 144         .poll =  iio_event_poll,
 145         .release = iio_event_chrdev_release,
 146         .owner = THIS_MODULE,
 147         .llseek = noop_llseek,
 148 };
 149
 150 int iio_event_getfd(struct iio_dev *indio_dev)
 151 {
 152         struct iio_event_interface *ev_int = indio_dev->event_interface;
 153         int fd;
 154
 155         if (ev_int == NULL)
 156                 return -ENODEV;
 157
 158         spin_lock_irq(&ev_int->wait.lock);
 159         if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 160                 spin_unlock_irq(&ev_int->wait.lock);
 161                 return -EBUSY;
 162         }
 163         spin_unlock_irq(&ev_int->wait.lock);
 164         fd = anon_inode_getfd("iio:event",
 165                                 &iio_event_chrdev_fileops, ev_int, O_RDONLY);
 166         if (fd < 0) {
 167                 spin_lock_irq(&ev_int->wait.lock);
 168                 __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 169                 spin_unlock_irq(&ev_int->wait.lock);
 170         }
 171         return fd;
 172 }
 173
 174 static const char * const iio_ev_type_text[] = {
 175         [IIO_EV_TYPE_THRESH] = "thresh",
 176         [IIO_EV_TYPE_MAG] = "mag",
 177         [IIO_EV_TYPE_ROC] = "roc",
 178         [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 179         [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 180 };
 181
 182 static const char * const iio_ev_dir_text[] = {
 183         [IIO_EV_DIR_EITHER] = "either",
 184         [IIO_EV_DIR_RISING] = "rising",
 185         [IIO_EV_DIR_FALLING] = "falling"
 186 };
 187
 188 static ssize_t iio_ev_state_store(struct device *dev,
 189                                   struct device_attribute *attr,
 190                                   const char *buf,
 191                                   size_t len)
 192 {
 193         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 194         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 195         int ret;
 196         bool val;
 197
 198         ret = strtobool(buf, &val);
 199         if (ret < 0)
 200                 return ret;
 201
 202         ret = indio_dev->info->write_event_config(indio_dev,
 203                                                   this_attr->address,
 204                                                   val);
 205         return (ret < 0) ? ret : len;
 206 }
 207
 208 static ssize_t iio_ev_state_show(struct device *dev,
 209                                  struct device_attribute *attr,
 210                                  char *buf)
 211 {
 212         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 213         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 214         int val = indio_dev->info->read_event_config(indio_dev,
 215                                                      this_attr->address);
 216
 217         if (val < 0)
 218                 return val;
 219         else
 220                 return sprintf(buf, "%d\n", val);
 221 }
 222
 223 static ssize_t iio_ev_value_show(struct device *dev,
 224                                  struct device_attribute *attr,
 225                                  char *buf)
 226 {
 227         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 228         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 229         int val, ret;
 230
 231         ret = indio_dev->info->read_event_value(indio_dev,
 232                                                 this_attr->address, &val);
 233         if (ret < 0)
 234                 return ret;
 235
 236         return sprintf(buf, "%d\n", val);
 237 }
 238
 239 static ssize_t iio_ev_value_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 val;
 247         int ret;
 248
 249         if (!indio_dev->info->write_event_value)
 250                 return -EINVAL;
 251
 252         ret = kstrtoint(buf, 10, &val);
 253         if (ret)
 254                 return ret;
 255
 256         ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
 257                                                  val);
 258         if (ret < 0)
 259                 return ret;
 260
 261         return len;
 262 }
 263
 264 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 265                                       struct iio_chan_spec const *chan)
 266 {
 267         int ret = 0, i, attrcount = 0;
 268         u64 mask = 0;
 269         char *postfix;
 270         if (!chan->event_mask)
 271                 return 0;
 272
 273         for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
 274                 postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
 275                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 276                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 277                 if (postfix == NULL) {
 278                         ret = -ENOMEM;
 279                         goto error_ret;
 280                 }
 281                 if (chan->modified)
 282                         mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel,
 283                                                   i/IIO_EV_DIR_MAX,
 284                                                   i%IIO_EV_DIR_MAX);
 285                 else if (chan->differential)
 286                         mask = IIO_EVENT_CODE(chan->type,
 287                                               0, 0,
 288                                               i%IIO_EV_DIR_MAX,
 289                                               i/IIO_EV_DIR_MAX,
 290                                               0,
 291                                               chan->channel,
 292                                               chan->channel2);
 293                 else
 294                         mask = IIO_UNMOD_EVENT_CODE(chan->type,
 295                                                     chan->channel,
 296                                                     i/IIO_EV_DIR_MAX,
 297                                                     i%IIO_EV_DIR_MAX);
 298
 299                 ret = __iio_add_chan_devattr(postfix,
 300                                              chan,
 301                                              &iio_ev_state_show,
 302                                              iio_ev_state_store,
 303                                              mask,
 304                                              0,
 305                                              &indio_dev->dev,
 306                                              &indio_dev->event_interface->
 307                                              dev_attr_list);
 308                 kfree(postfix);
 309                 if (ret)
 310                         goto error_ret;
 311                 attrcount++;
 312                 postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
 313                                     iio_ev_type_text[i/IIO_EV_DIR_MAX],
 314                                     iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 315                 if (postfix == NULL) {
 316                         ret = -ENOMEM;
 317                         goto error_ret;
 318                 }
 319                 ret = __iio_add_chan_devattr(postfix, chan,
 320                                              iio_ev_value_show,
 321                                              iio_ev_value_store,
 322                                              mask,
 323                                              0,
 324                                              &indio_dev->dev,
 325                                              &indio_dev->event_interface->
 326                                              dev_attr_list);
 327                 kfree(postfix);
 328                 if (ret)
 329                         goto error_ret;
 330                 attrcount++;
 331         }
 332         ret = attrcount;
 333 error_ret:
 334         return ret;
 335 }
 336
 337 static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
 338 {
 339         struct iio_dev_attr *p, *n;
 340         list_for_each_entry_safe(p, n,
 341                                  &indio_dev->event_interface->
 342                                  dev_attr_list, l) {
 343                 kfree(p->dev_attr.attr.name);
 344                 kfree(p);
 345         }
 346 }
 347
 348 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 349 {
 350         int j, ret, attrcount = 0;
 351
 352         /* Dynically created from the channels array */
 353         for (j = 0; j < indio_dev->num_channels; j++) {
 354                 ret = iio_device_add_event_sysfs(indio_dev,
 355                                                  &indio_dev->channels[j]);
 356                 if (ret < 0)
 357                         return ret;
 358                 attrcount += ret;
 359         }
 360         return attrcount;
 361 }
 362
 363 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 364 {
 365         int j;
 366
 367         for (j = 0; j < indio_dev->num_channels; j++)
 368                 if (indio_dev->channels[j].event_mask != 0)
 369                         return true;
 370         return false;
 371 }
 372
 373 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 374 {
 375         INIT_KFIFO(ev_int->det_events);
 376         init_waitqueue_head(&ev_int->wait);
 377         mutex_init(&ev_int->read_lock);
 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         mutex_destroy(&indio_dev->event_interface->read_lock);
 442         kfree(indio_dev->event_interface);
 443 error_ret:
 444
 445         return ret;
 446 }
 447
 448 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 449 {
 450         if (indio_dev->event_interface == NULL)
 451                 return;
 452         __iio_remove_event_config_attrs(indio_dev);
 453         kfree(indio_dev->event_interface->group.attrs);
 454         mutex_destroy(&indio_dev->event_interface->read_lock);
 455         kfree(indio_dev->event_interface);
 456 }