1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Industrial I/O event handling
3 *
4 * Copyright (c) 2008 Jonathan Cameron
5 *
6 * Based on elements of hwmon and input subsystems.
7 */
8
9 #include <linux/anon_inodes.h>
10 #include <linux/device.h>
11 #include <linux/fs.h>
12 #include <linux/kernel.h>
13 #include <linux/kfifo.h>
14 #include <linux/module.h>
15 #include <linux/poll.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/uaccess.h>
19 #include <linux/wait.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/iio-opaque.h>
22 #include "iio_core.h"
23 #include <linux/iio/sysfs.h>
24 #include <linux/iio/events.h>
25
26 /**
27 * struct iio_event_interface - chrdev interface for an event line
28 * @wait: wait queue to allow blocking reads of events
29 * @det_events: list of detected events
30 * @dev_attr_list: list of event interface sysfs attribute
31 * @flags: file operations related flags including busy flag.
32 * @group: event interface sysfs attribute group
33 * @read_lock: lock to protect kfifo read operations
34 */
35 struct iio_event_interface {
36 wait_queue_head_t wait;
37 DECLARE_KFIFO(det_events, struct iio_event_data, 16);
38
39 struct list_head dev_attr_list;
40 unsigned long flags;
41 struct attribute_group group;
42 struct mutex read_lock;
43 };
44
iio_event_enabled(const struct iio_event_interface * ev_int)45 bool iio_event_enabled(const struct iio_event_interface *ev_int)
46 {
47 return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
48 }
49
50 /**
51 * iio_push_event() - try to add event to the list for userspace reading
52 * @indio_dev: IIO device structure
53 * @ev_code: What event
54 * @timestamp: When the event occurred
55 *
56 * Note: The caller must make sure that this function is not running
57 * concurrently for the same indio_dev more than once.
58 *
59 * This function may be safely used as soon as a valid reference to iio_dev has
60 * been obtained via iio_device_alloc(), but any events that are submitted
61 * before iio_device_register() has successfully completed will be silently
62 * discarded.
63 **/
iio_push_event(struct iio_dev * indio_dev,u64 ev_code,s64 timestamp)64 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
65 {
66 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
67 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
68 struct iio_event_data ev;
69 int copied;
70
71 if (!ev_int)
72 return 0;
73
74 /* Does anyone care? */
75 if (iio_event_enabled(ev_int)) {
76
77 ev.id = ev_code;
78 ev.timestamp = timestamp;
79
80 copied = kfifo_put(&ev_int->det_events, ev);
81 if (copied != 0)
82 wake_up_poll(&ev_int->wait, EPOLLIN);
83 }
84
85 return 0;
86 }
87 EXPORT_SYMBOL(iio_push_event);
88
89 /**
90 * iio_event_poll() - poll the event queue to find out if it has data
91 * @filep: File structure pointer to identify the device
92 * @wait: Poll table pointer to add the wait queue on
93 *
94 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
95 * or a negative error code on failure
96 */
iio_event_poll(struct file * filep,struct poll_table_struct * wait)97 static __poll_t iio_event_poll(struct file *filep,
98 struct poll_table_struct *wait)
99 {
100 struct iio_dev *indio_dev = filep->private_data;
101 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
102 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
103 __poll_t events = 0;
104
105 if (!indio_dev->info)
106 return events;
107
108 poll_wait(filep, &ev_int->wait, wait);
109
110 if (!kfifo_is_empty(&ev_int->det_events))
111 events = EPOLLIN | EPOLLRDNORM;
112
113 return events;
114 }
115
iio_event_chrdev_read(struct file * filep,char __user * buf,size_t count,loff_t * f_ps)116 static ssize_t iio_event_chrdev_read(struct file *filep,
117 char __user *buf,
118 size_t count,
119 loff_t *f_ps)
120 {
121 struct iio_dev *indio_dev = filep->private_data;
122 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
123 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
124 unsigned int copied;
125 int ret;
126
127 if (!indio_dev->info)
128 return -ENODEV;
129
130 if (count < sizeof(struct iio_event_data))
131 return -EINVAL;
132
133 do {
134 if (kfifo_is_empty(&ev_int->det_events)) {
135 if (filep->f_flags & O_NONBLOCK)
136 return -EAGAIN;
137
138 ret = wait_event_interruptible(ev_int->wait,
139 !kfifo_is_empty(&ev_int->det_events) ||
140 indio_dev->info == NULL);
141 if (ret)
142 return ret;
143 if (indio_dev->info == NULL)
144 return -ENODEV;
145 }
146
147 if (mutex_lock_interruptible(&ev_int->read_lock))
148 return -ERESTARTSYS;
149 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
150 mutex_unlock(&ev_int->read_lock);
151
152 if (ret)
153 return ret;
154
155 /*
156 * If we couldn't read anything from the fifo (a different
157 * thread might have been faster) we either return -EAGAIN if
158 * the file descriptor is non-blocking, otherwise we go back to
159 * sleep and wait for more data to arrive.
160 */
161 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
162 return -EAGAIN;
163
164 } while (copied == 0);
165
166 return copied;
167 }
168
iio_event_chrdev_release(struct inode * inode,struct file * filep)169 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
170 {
171 struct iio_dev *indio_dev = filep->private_data;
172 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
173 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
174
175 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
176
177 iio_device_put(indio_dev);
178
179 return 0;
180 }
181
182 static const struct file_operations iio_event_chrdev_fileops = {
183 .read = iio_event_chrdev_read,
184 .poll = iio_event_poll,
185 .release = iio_event_chrdev_release,
186 .owner = THIS_MODULE,
187 .llseek = noop_llseek,
188 };
189
iio_event_getfd(struct iio_dev * indio_dev)190 int iio_event_getfd(struct iio_dev *indio_dev)
191 {
192 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
193 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
194 int fd;
195
196 if (ev_int == NULL)
197 return -ENODEV;
198
199 fd = mutex_lock_interruptible(&indio_dev->mlock);
200 if (fd)
201 return fd;
202
203 if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
204 fd = -EBUSY;
205 goto unlock;
206 }
207
208 iio_device_get(indio_dev);
209
210 fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
211 indio_dev, O_RDONLY | O_CLOEXEC);
212 if (fd < 0) {
213 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
214 iio_device_put(indio_dev);
215 } else {
216 kfifo_reset_out(&ev_int->det_events);
217 }
218
219 unlock:
220 mutex_unlock(&indio_dev->mlock);
221 return fd;
222 }
223
224 static const char * const iio_ev_type_text[] = {
225 [IIO_EV_TYPE_THRESH] = "thresh",
226 [IIO_EV_TYPE_MAG] = "mag",
227 [IIO_EV_TYPE_ROC] = "roc",
228 [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
229 [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
230 [IIO_EV_TYPE_CHANGE] = "change",
231 #ifdef CONFIG_NO_GKI
232 [IIO_EV_TYPE_FIFO_FLUSH] = "fifo_flush",
233 #endif
234 };
235
236 static const char * const iio_ev_dir_text[] = {
237 [IIO_EV_DIR_EITHER] = "either",
238 [IIO_EV_DIR_RISING] = "rising",
239 [IIO_EV_DIR_FALLING] = "falling",
240 #ifdef CONFIG_NO_GKI
241 [IIO_EV_DIR_FIFO_EMPTY] = "empty",
242 [IIO_EV_DIR_FIFO_DATA] = "data",
243 #endif
244 };
245
246 static const char * const iio_ev_info_text[] = {
247 [IIO_EV_INFO_ENABLE] = "en",
248 [IIO_EV_INFO_VALUE] = "value",
249 [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
250 [IIO_EV_INFO_PERIOD] = "period",
251 [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
252 [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
253 };
254
iio_ev_attr_dir(struct iio_dev_attr * attr)255 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
256 {
257 return attr->c->event_spec[attr->address & 0xffff].dir;
258 }
259
iio_ev_attr_type(struct iio_dev_attr * attr)260 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
261 {
262 return attr->c->event_spec[attr->address & 0xffff].type;
263 }
264
iio_ev_attr_info(struct iio_dev_attr * attr)265 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
266 {
267 return (attr->address >> 16) & 0xffff;
268 }
269
iio_ev_state_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)270 static ssize_t iio_ev_state_store(struct device *dev,
271 struct device_attribute *attr,
272 const char *buf,
273 size_t len)
274 {
275 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
276 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
277 int ret;
278 bool val;
279
280 ret = strtobool(buf, &val);
281 if (ret < 0)
282 return ret;
283
284 ret = indio_dev->info->write_event_config(indio_dev,
285 this_attr->c, iio_ev_attr_type(this_attr),
286 iio_ev_attr_dir(this_attr), val);
287
288 return (ret < 0) ? ret : len;
289 }
290
iio_ev_state_show(struct device * dev,struct device_attribute * attr,char * buf)291 static ssize_t iio_ev_state_show(struct device *dev,
292 struct device_attribute *attr,
293 char *buf)
294 {
295 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
296 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
297 int val;
298
299 val = indio_dev->info->read_event_config(indio_dev,
300 this_attr->c, iio_ev_attr_type(this_attr),
301 iio_ev_attr_dir(this_attr));
302 if (val < 0)
303 return val;
304 else
305 return sprintf(buf, "%d\n", val);
306 }
307
iio_ev_value_show(struct device * dev,struct device_attribute * attr,char * buf)308 static ssize_t iio_ev_value_show(struct device *dev,
309 struct device_attribute *attr,
310 char *buf)
311 {
312 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
313 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
314 int val, val2, val_arr[2];
315 int ret;
316
317 ret = indio_dev->info->read_event_value(indio_dev,
318 this_attr->c, iio_ev_attr_type(this_attr),
319 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
320 &val, &val2);
321 if (ret < 0)
322 return ret;
323 val_arr[0] = val;
324 val_arr[1] = val2;
325 return iio_format_value(buf, ret, 2, val_arr);
326 }
327
iio_ev_value_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)328 static ssize_t iio_ev_value_store(struct device *dev,
329 struct device_attribute *attr,
330 const char *buf,
331 size_t len)
332 {
333 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
334 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
335 int val, val2;
336 int ret;
337
338 if (!indio_dev->info->write_event_value)
339 return -EINVAL;
340
341 ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
342 if (ret)
343 return ret;
344 ret = indio_dev->info->write_event_value(indio_dev,
345 this_attr->c, iio_ev_attr_type(this_attr),
346 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
347 val, val2);
348 if (ret < 0)
349 return ret;
350
351 return len;
352 }
353
iio_device_add_event(struct iio_dev * indio_dev,const struct iio_chan_spec * chan,unsigned int spec_index,enum iio_event_type type,enum iio_event_direction dir,enum iio_shared_by shared_by,const unsigned long * mask)354 static int iio_device_add_event(struct iio_dev *indio_dev,
355 const struct iio_chan_spec *chan, unsigned int spec_index,
356 enum iio_event_type type, enum iio_event_direction dir,
357 enum iio_shared_by shared_by, const unsigned long *mask)
358 {
359 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
360 ssize_t (*show)(struct device *, struct device_attribute *, char *);
361 ssize_t (*store)(struct device *, struct device_attribute *,
362 const char *, size_t);
363 unsigned int attrcount = 0;
364 unsigned int i;
365 char *postfix;
366 int ret;
367
368 for_each_set_bit(i, mask, sizeof(*mask)*8) {
369 if (i >= ARRAY_SIZE(iio_ev_info_text))
370 return -EINVAL;
371 if (dir != IIO_EV_DIR_NONE)
372 postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
373 iio_ev_type_text[type],
374 iio_ev_dir_text[dir],
375 iio_ev_info_text[i]);
376 else
377 postfix = kasprintf(GFP_KERNEL, "%s_%s",
378 iio_ev_type_text[type],
379 iio_ev_info_text[i]);
380 if (postfix == NULL)
381 return -ENOMEM;
382
383 if (i == IIO_EV_INFO_ENABLE) {
384 show = iio_ev_state_show;
385 store = iio_ev_state_store;
386 } else {
387 show = iio_ev_value_show;
388 store = iio_ev_value_store;
389 }
390
391 ret = __iio_add_chan_devattr(postfix, chan, show, store,
392 (i << 16) | spec_index, shared_by, &indio_dev->dev,
393 &iio_dev_opaque->event_interface->dev_attr_list);
394 kfree(postfix);
395
396 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
397 continue;
398
399 if (ret)
400 return ret;
401
402 attrcount++;
403 }
404
405 return attrcount;
406 }
407
iio_device_add_event_sysfs(struct iio_dev * indio_dev,struct iio_chan_spec const * chan)408 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
409 struct iio_chan_spec const *chan)
410 {
411 int ret = 0, i, attrcount = 0;
412 enum iio_event_direction dir;
413 enum iio_event_type type;
414
415 for (i = 0; i < chan->num_event_specs; i++) {
416 type = chan->event_spec[i].type;
417 dir = chan->event_spec[i].dir;
418
419 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
420 IIO_SEPARATE, &chan->event_spec[i].mask_separate);
421 if (ret < 0)
422 return ret;
423 attrcount += ret;
424
425 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
426 IIO_SHARED_BY_TYPE,
427 &chan->event_spec[i].mask_shared_by_type);
428 if (ret < 0)
429 return ret;
430 attrcount += ret;
431
432 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
433 IIO_SHARED_BY_DIR,
434 &chan->event_spec[i].mask_shared_by_dir);
435 if (ret < 0)
436 return ret;
437 attrcount += ret;
438
439 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
440 IIO_SHARED_BY_ALL,
441 &chan->event_spec[i].mask_shared_by_all);
442 if (ret < 0)
443 return ret;
444 attrcount += ret;
445 }
446 ret = attrcount;
447 return ret;
448 }
449
__iio_add_event_config_attrs(struct iio_dev * indio_dev)450 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
451 {
452 int j, ret, attrcount = 0;
453
454 /* Dynamically created from the channels array */
455 for (j = 0; j < indio_dev->num_channels; j++) {
456 ret = iio_device_add_event_sysfs(indio_dev,
457 &indio_dev->channels[j]);
458 if (ret < 0)
459 return ret;
460 attrcount += ret;
461 }
462 return attrcount;
463 }
464
iio_check_for_dynamic_events(struct iio_dev * indio_dev)465 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
466 {
467 int j;
468
469 for (j = 0; j < indio_dev->num_channels; j++) {
470 if (indio_dev->channels[j].num_event_specs != 0)
471 return true;
472 }
473 return false;
474 }
475
iio_setup_ev_int(struct iio_event_interface * ev_int)476 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
477 {
478 INIT_KFIFO(ev_int->det_events);
479 init_waitqueue_head(&ev_int->wait);
480 mutex_init(&ev_int->read_lock);
481 }
482
483 static const char *iio_event_group_name = "events";
iio_device_register_eventset(struct iio_dev * indio_dev)484 int iio_device_register_eventset(struct iio_dev *indio_dev)
485 {
486 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
487 struct iio_event_interface *ev_int;
488 struct iio_dev_attr *p;
489 int ret = 0, attrcount_orig = 0, attrcount, attrn;
490 struct attribute **attr;
491
492 if (!(indio_dev->info->event_attrs ||
493 iio_check_for_dynamic_events(indio_dev)))
494 return 0;
495
496 ev_int = kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
497 if (ev_int == NULL)
498 return -ENOMEM;
499
500 iio_dev_opaque->event_interface = ev_int;
501
502 INIT_LIST_HEAD(&ev_int->dev_attr_list);
503
504 iio_setup_ev_int(ev_int);
505 if (indio_dev->info->event_attrs != NULL) {
506 attr = indio_dev->info->event_attrs->attrs;
507 while (*attr++ != NULL)
508 attrcount_orig++;
509 }
510 attrcount = attrcount_orig;
511 if (indio_dev->channels) {
512 ret = __iio_add_event_config_attrs(indio_dev);
513 if (ret < 0)
514 goto error_free_setup_event_lines;
515 attrcount += ret;
516 }
517
518 ev_int->group.name = iio_event_group_name;
519 ev_int->group.attrs = kcalloc(attrcount + 1,
520 sizeof(ev_int->group.attrs[0]),
521 GFP_KERNEL);
522 if (ev_int->group.attrs == NULL) {
523 ret = -ENOMEM;
524 goto error_free_setup_event_lines;
525 }
526 if (indio_dev->info->event_attrs)
527 memcpy(ev_int->group.attrs,
528 indio_dev->info->event_attrs->attrs,
529 sizeof(ev_int->group.attrs[0]) * attrcount_orig);
530 attrn = attrcount_orig;
531 /* Add all elements from the list. */
532 list_for_each_entry(p, &ev_int->dev_attr_list, l)
533 ev_int->group.attrs[attrn++] = &p->dev_attr.attr;
534 indio_dev->groups[indio_dev->groupcounter++] = &ev_int->group;
535
536 return 0;
537
538 error_free_setup_event_lines:
539 iio_free_chan_devattr_list(&ev_int->dev_attr_list);
540 kfree(ev_int);
541 iio_dev_opaque->event_interface = NULL;
542 return ret;
543 }
544
545 /**
546 * iio_device_wakeup_eventset - Wakes up the event waitqueue
547 * @indio_dev: The IIO device
548 *
549 * Wakes up the event waitqueue used for poll() and blocking read().
550 * Should usually be called when the device is unregistered.
551 */
iio_device_wakeup_eventset(struct iio_dev * indio_dev)552 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
553 {
554 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
555
556 if (iio_dev_opaque->event_interface == NULL)
557 return;
558 wake_up(&iio_dev_opaque->event_interface->wait);
559 }
560
iio_device_unregister_eventset(struct iio_dev * indio_dev)561 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
562 {
563 struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
564 struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
565
566 if (ev_int == NULL)
567 return;
568 iio_free_chan_devattr_list(&ev_int->dev_attr_list);
569 kfree(ev_int->group.attrs);
570 kfree(ev_int);
571 iio_dev_opaque->event_interface = NULL;
572 }
573