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 	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  **/
55 int 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 }
74 EXPORT_SYMBOL(iio_push_event);
75 
76 /**
77  * iio_event_poll() - poll the event queue to find out if it has data
78  */
79 static 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 -ENODEV;
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 
97 static 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 
149 static 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 
161 static 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 
169 int 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 
194 static 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 };
201 
202 static const char * const iio_ev_dir_text[] = {
203 	[IIO_EV_DIR_EITHER] = "either",
204 	[IIO_EV_DIR_RISING] = "rising",
205 	[IIO_EV_DIR_FALLING] = "falling"
206 };
207 
208 static const char * const iio_ev_info_text[] = {
209 	[IIO_EV_INFO_ENABLE] = "en",
210 	[IIO_EV_INFO_VALUE] = "value",
211 	[IIO_EV_INFO_HYSTERESIS] = "hysteresis",
212 	[IIO_EV_INFO_PERIOD] = "period",
213 };
214 
215 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
216 {
217 	return attr->c->event_spec[attr->address & 0xffff].dir;
218 }
219 
220 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
221 {
222 	return attr->c->event_spec[attr->address & 0xffff].type;
223 }
224 
225 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
226 {
227 	return (attr->address >> 16) & 0xffff;
228 }
229 
230 static ssize_t iio_ev_state_store(struct device *dev,
231 				  struct device_attribute *attr,
232 				  const char *buf,
233 				  size_t len)
234 {
235 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
236 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
237 	int ret;
238 	bool val;
239 
240 	ret = strtobool(buf, &val);
241 	if (ret < 0)
242 		return ret;
243 
244 	ret = indio_dev->info->write_event_config(indio_dev,
245 		this_attr->c, iio_ev_attr_type(this_attr),
246 		iio_ev_attr_dir(this_attr), val);
247 
248 	return (ret < 0) ? ret : len;
249 }
250 
251 static ssize_t iio_ev_state_show(struct device *dev,
252 				 struct device_attribute *attr,
253 				 char *buf)
254 {
255 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
256 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
257 	int val;
258 
259 	val = indio_dev->info->read_event_config(indio_dev,
260 		this_attr->c, iio_ev_attr_type(this_attr),
261 		iio_ev_attr_dir(this_attr));
262 	if (val < 0)
263 		return val;
264 	else
265 		return sprintf(buf, "%d\n", val);
266 }
267 
268 static ssize_t iio_ev_value_show(struct device *dev,
269 				 struct device_attribute *attr,
270 				 char *buf)
271 {
272 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
273 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
274 	int val, val2, val_arr[2];
275 	int ret;
276 
277 	ret = indio_dev->info->read_event_value(indio_dev,
278 		this_attr->c, iio_ev_attr_type(this_attr),
279 		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
280 		&val, &val2);
281 	if (ret < 0)
282 		return ret;
283 	val_arr[0] = val;
284 	val_arr[1] = val2;
285 	return iio_format_value(buf, ret, 2, val_arr);
286 }
287 
288 static ssize_t iio_ev_value_store(struct device *dev,
289 				  struct device_attribute *attr,
290 				  const char *buf,
291 				  size_t len)
292 {
293 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
294 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
295 	int val, val2;
296 	int ret;
297 
298 	if (!indio_dev->info->write_event_value)
299 		return -EINVAL;
300 
301 	ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
302 	if (ret)
303 		return ret;
304 	ret = indio_dev->info->write_event_value(indio_dev,
305 		this_attr->c, iio_ev_attr_type(this_attr),
306 		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
307 		val, val2);
308 	if (ret < 0)
309 		return ret;
310 
311 	return len;
312 }
313 
314 static int iio_device_add_event(struct iio_dev *indio_dev,
315 	const struct iio_chan_spec *chan, unsigned int spec_index,
316 	enum iio_event_type type, enum iio_event_direction dir,
317 	enum iio_shared_by shared_by, const unsigned long *mask)
318 {
319 	ssize_t (*show)(struct device *, struct device_attribute *, char *);
320 	ssize_t (*store)(struct device *, struct device_attribute *,
321 		const char *, size_t);
322 	unsigned int attrcount = 0;
323 	unsigned int i;
324 	char *postfix;
325 	int ret;
326 
327 	for_each_set_bit(i, mask, sizeof(*mask)*8) {
328 		if (i >= ARRAY_SIZE(iio_ev_info_text))
329 			return -EINVAL;
330 		postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
331 				iio_ev_type_text[type], iio_ev_dir_text[dir],
332 				iio_ev_info_text[i]);
333 		if (postfix == NULL)
334 			return -ENOMEM;
335 
336 		if (i == IIO_EV_INFO_ENABLE) {
337 			show = iio_ev_state_show;
338 			store = iio_ev_state_store;
339 		} else {
340 			show = iio_ev_value_show;
341 			store = iio_ev_value_store;
342 		}
343 
344 		ret = __iio_add_chan_devattr(postfix, chan, show, store,
345 			 (i << 16) | spec_index, shared_by, &indio_dev->dev,
346 			&indio_dev->event_interface->dev_attr_list);
347 		kfree(postfix);
348 
349 		if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
350 			continue;
351 
352 		if (ret)
353 			return ret;
354 
355 		attrcount++;
356 	}
357 
358 	return attrcount;
359 }
360 
361 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
362 	struct iio_chan_spec const *chan)
363 {
364 	int ret = 0, i, attrcount = 0;
365 	enum iio_event_direction dir;
366 	enum iio_event_type type;
367 
368 	for (i = 0; i < chan->num_event_specs; i++) {
369 		type = chan->event_spec[i].type;
370 		dir = chan->event_spec[i].dir;
371 
372 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
373 			IIO_SEPARATE, &chan->event_spec[i].mask_separate);
374 		if (ret < 0)
375 			return ret;
376 		attrcount += ret;
377 
378 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
379 			IIO_SHARED_BY_TYPE,
380 			&chan->event_spec[i].mask_shared_by_type);
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_DIR,
387 			&chan->event_spec[i].mask_shared_by_dir);
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_ALL,
394 			&chan->event_spec[i].mask_shared_by_all);
395 		if (ret < 0)
396 			return ret;
397 		attrcount += ret;
398 	}
399 	ret = attrcount;
400 	return ret;
401 }
402 
403 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
404 {
405 	int j, ret, attrcount = 0;
406 
407 	/* Dynically created from the channels array */
408 	for (j = 0; j < indio_dev->num_channels; j++) {
409 		ret = iio_device_add_event_sysfs(indio_dev,
410 						 &indio_dev->channels[j]);
411 		if (ret < 0)
412 			return ret;
413 		attrcount += ret;
414 	}
415 	return attrcount;
416 }
417 
418 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
419 {
420 	int j;
421 
422 	for (j = 0; j < indio_dev->num_channels; j++) {
423 		if (indio_dev->channels[j].num_event_specs != 0)
424 			return true;
425 	}
426 	return false;
427 }
428 
429 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
430 {
431 	INIT_KFIFO(ev_int->det_events);
432 	init_waitqueue_head(&ev_int->wait);
433 	mutex_init(&ev_int->read_lock);
434 }
435 
436 static const char *iio_event_group_name = "events";
437 int iio_device_register_eventset(struct iio_dev *indio_dev)
438 {
439 	struct iio_dev_attr *p;
440 	int ret = 0, attrcount_orig = 0, attrcount, attrn;
441 	struct attribute **attr;
442 
443 	if (!(indio_dev->info->event_attrs ||
444 	      iio_check_for_dynamic_events(indio_dev)))
445 		return 0;
446 
447 	indio_dev->event_interface =
448 		kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
449 	if (indio_dev->event_interface == NULL)
450 		return -ENOMEM;
451 
452 	INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
453 
454 	iio_setup_ev_int(indio_dev->event_interface);
455 	if (indio_dev->info->event_attrs != NULL) {
456 		attr = indio_dev->info->event_attrs->attrs;
457 		while (*attr++ != NULL)
458 			attrcount_orig++;
459 	}
460 	attrcount = attrcount_orig;
461 	if (indio_dev->channels) {
462 		ret = __iio_add_event_config_attrs(indio_dev);
463 		if (ret < 0)
464 			goto error_free_setup_event_lines;
465 		attrcount += ret;
466 	}
467 
468 	indio_dev->event_interface->group.name = iio_event_group_name;
469 	indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
470 							  sizeof(indio_dev->event_interface->group.attrs[0]),
471 							  GFP_KERNEL);
472 	if (indio_dev->event_interface->group.attrs == NULL) {
473 		ret = -ENOMEM;
474 		goto error_free_setup_event_lines;
475 	}
476 	if (indio_dev->info->event_attrs)
477 		memcpy(indio_dev->event_interface->group.attrs,
478 		       indio_dev->info->event_attrs->attrs,
479 		       sizeof(indio_dev->event_interface->group.attrs[0])
480 		       *attrcount_orig);
481 	attrn = attrcount_orig;
482 	/* Add all elements from the list. */
483 	list_for_each_entry(p,
484 			    &indio_dev->event_interface->dev_attr_list,
485 			    l)
486 		indio_dev->event_interface->group.attrs[attrn++] =
487 			&p->dev_attr.attr;
488 	indio_dev->groups[indio_dev->groupcounter++] =
489 		&indio_dev->event_interface->group;
490 
491 	return 0;
492 
493 error_free_setup_event_lines:
494 	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
495 	kfree(indio_dev->event_interface);
496 	return ret;
497 }
498 
499 /**
500  * iio_device_wakeup_eventset - Wakes up the event waitqueue
501  * @indio_dev: The IIO device
502  *
503  * Wakes up the event waitqueue used for poll() and blocking read().
504  * Should usually be called when the device is unregistered.
505  */
506 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
507 {
508 	if (indio_dev->event_interface == NULL)
509 		return;
510 	wake_up(&indio_dev->event_interface->wait);
511 }
512 
513 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
514 {
515 	if (indio_dev->event_interface == NULL)
516 		return;
517 	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
518 	kfree(indio_dev->event_interface->group.attrs);
519 	kfree(indio_dev->event_interface);
520 }
521