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