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