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