industrialio-event.c

  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 * @ioctl_handler:	handler for event ioctl() calls
 35 */
 36struct 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	struct iio_ioctl_handler	ioctl_handler;
 45};
 46
 47bool iio_event_enabled(const struct iio_event_interface *ev_int)
 48{
 49	return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 50}
 51
 52/**
 53 * iio_push_event() - try to add event to the list for userspace reading
 54 * @indio_dev:		IIO device structure
 55 * @ev_code:		What event
 56 * @timestamp:		When the event occurred
 57 *
 58 * Note: The caller must make sure that this function is not running
 59 * concurrently for the same indio_dev more than once.
 60 *
 61 * This function may be safely used as soon as a valid reference to iio_dev has
 62 * been obtained via iio_device_alloc(), but any events that are submitted
 63 * before iio_device_register() has successfully completed will be silently
 64 * discarded.
 65 **/
 66int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
 67{
 68	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 69	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 70	struct iio_event_data ev;
 71	int copied;
 72
 73	if (!ev_int)
 74		return 0;
 75
 76	/* Does anyone care? */
 77	if (iio_event_enabled(ev_int)) {
 78
 79		ev.id = ev_code;
 80		ev.timestamp = timestamp;
 81
 82		copied = kfifo_put(&ev_int->det_events, ev);
 83		if (copied != 0)
 84			wake_up_poll(&ev_int->wait, EPOLLIN);
 85	}
 86
 87	return 0;
 88}
 89EXPORT_SYMBOL(iio_push_event);
 90
 91/**
 92 * iio_event_poll() - poll the event queue to find out if it has data
 93 * @filep:	File structure pointer to identify the device
 94 * @wait:	Poll table pointer to add the wait queue on
 95 *
 96 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
 97 *	   or a negative error code on failure
 98 */
 99static __poll_t iio_event_poll(struct file *filep,
100			     struct poll_table_struct *wait)
101{
102	struct iio_dev *indio_dev = filep->private_data;
103	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
104	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
105	__poll_t events = 0;
106
107	if (!indio_dev->info)
108		return events;
109
110	poll_wait(filep, &ev_int->wait, wait);
111
112	if (!kfifo_is_empty(&ev_int->det_events))
113		events = EPOLLIN | EPOLLRDNORM;
114
115	return events;
116}
117
118static ssize_t iio_event_chrdev_read(struct file *filep,
119				     char __user *buf,
120				     size_t count,
121				     loff_t *f_ps)
122{
123	struct iio_dev *indio_dev = filep->private_data;
124	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
125	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
126	unsigned int copied;
127	int ret;
128
129	if (!indio_dev->info)
130		return -ENODEV;
131
132	if (count < sizeof(struct iio_event_data))
133		return -EINVAL;
134
135	do {
136		if (kfifo_is_empty(&ev_int->det_events)) {
137			if (filep->f_flags & O_NONBLOCK)
138				return -EAGAIN;
139
140			ret = wait_event_interruptible(ev_int->wait,
141					!kfifo_is_empty(&ev_int->det_events) ||
142					indio_dev->info == NULL);
143			if (ret)
144				return ret;
145			if (indio_dev->info == NULL)
146				return -ENODEV;
147		}
148
149		if (mutex_lock_interruptible(&ev_int->read_lock))
150			return -ERESTARTSYS;
151		ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
152		mutex_unlock(&ev_int->read_lock);
153
154		if (ret)
155			return ret;
156
157		/*
158		 * If we couldn't read anything from the fifo (a different
159		 * thread might have been faster) we either return -EAGAIN if
160		 * the file descriptor is non-blocking, otherwise we go back to
161		 * sleep and wait for more data to arrive.
162		 */
163		if (copied == 0 && (filep->f_flags & O_NONBLOCK))
164			return -EAGAIN;
165
166	} while (copied == 0);
167
168	return copied;
169}
170
171static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
172{
173	struct iio_dev *indio_dev = filep->private_data;
174	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
175	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
176
177	clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
178
179	iio_device_put(indio_dev);
180
181	return 0;
182}
183
184static const struct file_operations iio_event_chrdev_fileops = {
185	.read =  iio_event_chrdev_read,
186	.poll =  iio_event_poll,
187	.release = iio_event_chrdev_release,
188	.owner = THIS_MODULE,
189	.llseek = noop_llseek,
190};
191
192static int iio_event_getfd(struct iio_dev *indio_dev)
193{
194	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
195	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
196	int fd;
197
198	if (ev_int == NULL)
199		return -ENODEV;
200
201	fd = mutex_lock_interruptible(&iio_dev_opaque->mlock);
202	if (fd)
203		return fd;
204
205	if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
206		fd = -EBUSY;
207		goto unlock;
208	}
209
210	iio_device_get(indio_dev);
211
212	fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
213				indio_dev, O_RDONLY | O_CLOEXEC);
214	if (fd < 0) {
215		clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
216		iio_device_put(indio_dev);
217	} else {
218		kfifo_reset_out(&ev_int->det_events);
219	}
220
221unlock:
222	mutex_unlock(&iio_dev_opaque->mlock);
223	return fd;
224}
225
226static const char * const iio_ev_type_text[] = {
227	[IIO_EV_TYPE_THRESH] = "thresh",
228	[IIO_EV_TYPE_MAG] = "mag",
229	[IIO_EV_TYPE_ROC] = "roc",
230	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
231	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
232	[IIO_EV_TYPE_CHANGE] = "change",
233	[IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
234	[IIO_EV_TYPE_GESTURE] = "gesture",
235	[IIO_EV_TYPE_FAULT] = "fault",
236};
237
238static const char * const iio_ev_dir_text[] = {
239	[IIO_EV_DIR_EITHER] = "either",
240	[IIO_EV_DIR_RISING] = "rising",
241	[IIO_EV_DIR_FALLING] = "falling",
242	[IIO_EV_DIR_SINGLETAP] = "singletap",
243	[IIO_EV_DIR_DOUBLETAP] = "doubletap",
244	[IIO_EV_DIR_FAULT_OPENWIRE] = "openwire",
245};
246
247static const char * const iio_ev_info_text[] = {
248	[IIO_EV_INFO_ENABLE] = "en",
249	[IIO_EV_INFO_VALUE] = "value",
250	[IIO_EV_INFO_HYSTERESIS] = "hysteresis",
251	[IIO_EV_INFO_PERIOD] = "period",
252	[IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
253	[IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
254	[IIO_EV_INFO_TIMEOUT] = "timeout",
255	[IIO_EV_INFO_RESET_TIMEOUT] = "reset_timeout",
256	[IIO_EV_INFO_TAP2_MIN_DELAY] = "tap2_min_delay",
257	[IIO_EV_INFO_RUNNING_PERIOD] = "runningperiod",
258	[IIO_EV_INFO_RUNNING_COUNT] = "runningcount",
259};
260
261static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
262{
263	return attr->c->event_spec[attr->address & 0xffff].dir;
264}
265
266static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
267{
268	return attr->c->event_spec[attr->address & 0xffff].type;
269}
270
271static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
272{
273	return (attr->address >> 16) & 0xffff;
274}
275
276static ssize_t iio_ev_state_store(struct device *dev,
277				  struct device_attribute *attr,
278				  const char *buf,
279				  size_t len)
280{
281	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
282	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
283	int ret;
284	bool val;
285
286	ret = kstrtobool(buf, &val);
287	if (ret < 0)
288		return ret;
289
290	if (!indio_dev->info->write_event_config)
291		return -EINVAL;
292
293	ret = indio_dev->info->write_event_config(indio_dev,
294		this_attr->c, iio_ev_attr_type(this_attr),
295		iio_ev_attr_dir(this_attr), val);
296
297	return (ret < 0) ? ret : len;
298}
299
300static ssize_t iio_ev_state_show(struct device *dev,
301				 struct device_attribute *attr,
302				 char *buf)
303{
304	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
305	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
306	int val;
307
308	if (!indio_dev->info->read_event_config)
309		return -EINVAL;
310
311	val = indio_dev->info->read_event_config(indio_dev,
312		this_attr->c, iio_ev_attr_type(this_attr),
313		iio_ev_attr_dir(this_attr));
314	if (val < 0)
315		return val;
316	else
317		return sysfs_emit(buf, "%d\n", val);
318}
319
320static ssize_t iio_ev_value_show(struct device *dev,
321				 struct device_attribute *attr,
322				 char *buf)
323{
324	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
325	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
326	int val, val2, val_arr[2];
327	int ret;
328
329	if (!indio_dev->info->read_event_value)
330		return -EINVAL;
331
332	ret = indio_dev->info->read_event_value(indio_dev,
333		this_attr->c, iio_ev_attr_type(this_attr),
334		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
335		&val, &val2);
336	if (ret < 0)
337		return ret;
338	val_arr[0] = val;
339	val_arr[1] = val2;
340	return iio_format_value(buf, ret, 2, val_arr);
341}
342
343static ssize_t iio_ev_value_store(struct device *dev,
344				  struct device_attribute *attr,
345				  const char *buf,
346				  size_t len)
347{
348	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
349	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
350	int val, val2;
351	int ret;
352
353	if (!indio_dev->info->write_event_value)
354		return -EINVAL;
355
356	ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
357	if (ret)
358		return ret;
359	ret = indio_dev->info->write_event_value(indio_dev,
360		this_attr->c, iio_ev_attr_type(this_attr),
361		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
362		val, val2);
363	if (ret < 0)
364		return ret;
365
366	return len;
367}
368
369static ssize_t iio_ev_label_show(struct device *dev,
370				 struct device_attribute *attr,
371				 char *buf)
372{
373	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
374	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
375
376	if (indio_dev->info->read_event_label)
377		return indio_dev->info->read_event_label(indio_dev,
378				 this_attr->c, iio_ev_attr_type(this_attr),
379				 iio_ev_attr_dir(this_attr), buf);
380
381	return -EINVAL;
382}
383
384static int iio_device_add_event(struct iio_dev *indio_dev,
385	const struct iio_chan_spec *chan, unsigned int spec_index,
386	enum iio_event_type type, enum iio_event_direction dir,
387	enum iio_shared_by shared_by, const unsigned long *mask)
388{
389	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
390	ssize_t (*show)(struct device *dev, struct device_attribute *attr,
391		char *buf);
392	ssize_t (*store)(struct device *dev, struct device_attribute *attr,
393		const char *buf, size_t len);
394	unsigned int attrcount = 0;
395	unsigned int i;
396	char *postfix;
397	int ret;
398
399	for_each_set_bit(i, mask, sizeof(*mask)*8) {
400		if (i >= ARRAY_SIZE(iio_ev_info_text))
401			return -EINVAL;
402		if (dir != IIO_EV_DIR_NONE)
403			postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
404					iio_ev_type_text[type],
405					iio_ev_dir_text[dir],
406					iio_ev_info_text[i]);
407		else
408			postfix = kasprintf(GFP_KERNEL, "%s_%s",
409					iio_ev_type_text[type],
410					iio_ev_info_text[i]);
411		if (postfix == NULL)
412			return -ENOMEM;
413
414		if (i == IIO_EV_INFO_ENABLE) {
415			show = iio_ev_state_show;
416			store = iio_ev_state_store;
417		} else {
418			show = iio_ev_value_show;
419			store = iio_ev_value_store;
420		}
421
422		ret = __iio_add_chan_devattr(postfix, chan, show, store,
423			 (i << 16) | spec_index, shared_by, &indio_dev->dev,
424			 NULL,
425			&iio_dev_opaque->event_interface->dev_attr_list);
426		kfree(postfix);
427
428		if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
429			continue;
430
431		if (ret)
432			return ret;
433
434		attrcount++;
435	}
436
437	return attrcount;
438}
439
440static int iio_device_add_event_label(struct iio_dev *indio_dev,
441				      const struct iio_chan_spec *chan,
442				      unsigned int spec_index,
443				      enum iio_event_type type,
444				      enum iio_event_direction dir)
445{
446	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
447	char *postfix;
448	int ret;
449
450	if (!indio_dev->info->read_event_label)
451		return 0;
452
453	if (dir != IIO_EV_DIR_NONE)
454		postfix = kasprintf(GFP_KERNEL, "%s_%s_label",
455				iio_ev_type_text[type],
456				iio_ev_dir_text[dir]);
457	else
458		postfix = kasprintf(GFP_KERNEL, "%s_label",
459				iio_ev_type_text[type]);
460	if (postfix == NULL)
461		return -ENOMEM;
462
463	ret = __iio_add_chan_devattr(postfix, chan, &iio_ev_label_show, NULL,
464				spec_index, IIO_SEPARATE, &indio_dev->dev, NULL,
465				&iio_dev_opaque->event_interface->dev_attr_list);
466
467	kfree(postfix);
468
469	if (ret < 0)
470		return ret;
471
472	return 1;
473}
474
475static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
476	struct iio_chan_spec const *chan)
477{
478	int ret = 0, i, attrcount = 0;
479	enum iio_event_direction dir;
480	enum iio_event_type type;
481
482	for (i = 0; i < chan->num_event_specs; i++) {
483		type = chan->event_spec[i].type;
484		dir = chan->event_spec[i].dir;
485
486		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
487			IIO_SEPARATE, &chan->event_spec[i].mask_separate);
488		if (ret < 0)
489			return ret;
490		attrcount += ret;
491
492		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
493			IIO_SHARED_BY_TYPE,
494			&chan->event_spec[i].mask_shared_by_type);
495		if (ret < 0)
496			return ret;
497		attrcount += ret;
498
499		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
500			IIO_SHARED_BY_DIR,
501			&chan->event_spec[i].mask_shared_by_dir);
502		if (ret < 0)
503			return ret;
504		attrcount += ret;
505
506		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
507			IIO_SHARED_BY_ALL,
508			&chan->event_spec[i].mask_shared_by_all);
509		if (ret < 0)
510			return ret;
511		attrcount += ret;
512
513		ret = iio_device_add_event_label(indio_dev, chan, i, type, dir);
514		if (ret < 0)
515			return ret;
516		attrcount += ret;
517	}
518	ret = attrcount;
519	return ret;
520}
521
522static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
523{
524	int j, ret, attrcount = 0;
525
526	/* Dynamically created from the channels array */
527	for (j = 0; j < indio_dev->num_channels; j++) {
528		ret = iio_device_add_event_sysfs(indio_dev,
529						 &indio_dev->channels[j]);
530		if (ret < 0)
531			return ret;
532		attrcount += ret;
533	}
534	return attrcount;
535}
536
537static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
538{
539	int j;
540
541	for (j = 0; j < indio_dev->num_channels; j++) {
542		if (indio_dev->channels[j].num_event_specs != 0)
543			return true;
544	}
545	return false;
546}
547
548static void iio_setup_ev_int(struct iio_event_interface *ev_int)
549{
550	INIT_KFIFO(ev_int->det_events);
551	init_waitqueue_head(&ev_int->wait);
552	mutex_init(&ev_int->read_lock);
553}
554
555static long iio_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
556			    unsigned int cmd, unsigned long arg)
557{
558	int __user *ip = (int __user *)arg;
559	int fd;
560
561	if (cmd == IIO_GET_EVENT_FD_IOCTL) {
562		fd = iio_event_getfd(indio_dev);
563		if (fd < 0)
564			return fd;
565		if (copy_to_user(ip, &fd, sizeof(fd)))
566			return -EFAULT;
567		return 0;
568	}
569
570	return IIO_IOCTL_UNHANDLED;
571}
572
573static const char *iio_event_group_name = "events";
574int iio_device_register_eventset(struct iio_dev *indio_dev)
575{
576	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
577	struct iio_event_interface *ev_int;
578	struct iio_dev_attr *p;
579	int ret = 0, attrcount_orig = 0, attrcount, attrn;
580	struct attribute **attr;
581
582	if (!(indio_dev->info->event_attrs ||
583	      iio_check_for_dynamic_events(indio_dev)))
584		return 0;
585
586	ev_int = kzalloc(sizeof(*ev_int), GFP_KERNEL);
587	if (!ev_int)
588		return -ENOMEM;
589
590	iio_dev_opaque->event_interface = ev_int;
591
592	INIT_LIST_HEAD(&ev_int->dev_attr_list);
593
594	iio_setup_ev_int(ev_int);
595	if (indio_dev->info->event_attrs != NULL) {
596		attr = indio_dev->info->event_attrs->attrs;
597		while (*attr++ != NULL)
598			attrcount_orig++;
599	}
600	attrcount = attrcount_orig;
601	if (indio_dev->channels) {
602		ret = __iio_add_event_config_attrs(indio_dev);
603		if (ret < 0)
604			goto error_free_setup_event_lines;
605		attrcount += ret;
606	}
607
608	ev_int->group.name = iio_event_group_name;
609	ev_int->group.attrs = kcalloc(attrcount + 1,
610				      sizeof(ev_int->group.attrs[0]),
611				      GFP_KERNEL);
612	if (ev_int->group.attrs == NULL) {
613		ret = -ENOMEM;
614		goto error_free_setup_event_lines;
615	}
616	if (indio_dev->info->event_attrs)
617		memcpy(ev_int->group.attrs,
618		       indio_dev->info->event_attrs->attrs,
619		       sizeof(ev_int->group.attrs[0]) * attrcount_orig);
620	attrn = attrcount_orig;
621	/* Add all elements from the list. */
622	list_for_each_entry(p, &ev_int->dev_attr_list, l)
623		ev_int->group.attrs[attrn++] = &p->dev_attr.attr;
624
625	ret = iio_device_register_sysfs_group(indio_dev, &ev_int->group);
626	if (ret)
627		goto error_free_group_attrs;
628
629	ev_int->ioctl_handler.ioctl = iio_event_ioctl;
630	iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev,
631					  &ev_int->ioctl_handler);
632
633	return 0;
634
635error_free_group_attrs:
636	kfree(ev_int->group.attrs);
637error_free_setup_event_lines:
638	iio_free_chan_devattr_list(&ev_int->dev_attr_list);
639	kfree(ev_int);
640	iio_dev_opaque->event_interface = NULL;
641	return ret;
642}
643
644/**
645 * iio_device_wakeup_eventset - Wakes up the event waitqueue
646 * @indio_dev: The IIO device
647 *
648 * Wakes up the event waitqueue used for poll() and blocking read().
649 * Should usually be called when the device is unregistered.
650 */
651void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
652{
653	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
654
655	if (iio_dev_opaque->event_interface == NULL)
656		return;
657	wake_up(&iio_dev_opaque->event_interface->wait);
658}
659
660void iio_device_unregister_eventset(struct iio_dev *indio_dev)
661{
662	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
663	struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
664
665	if (ev_int == NULL)
666		return;
667
668	iio_device_ioctl_handler_unregister(&ev_int->ioctl_handler);
669	iio_free_chan_devattr_list(&ev_int->dev_attr_list);
670	kfree(ev_int->group.attrs);
671	kfree(ev_int);
672	iio_dev_opaque->event_interface = NULL;
673}