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 };
44 
45 /**
46  * iio_push_event() - try to add event to the list for userspace reading
47  * @indio_dev:		IIO device structure
48  * @ev_code:		What event
49  * @timestamp:		When the event occurred
50  **/
51 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
52 {
53 	struct iio_event_interface *ev_int = indio_dev->event_interface;
54 	struct iio_event_data ev;
55 	unsigned long flags;
56 	int copied;
57 
58 	/* Does anyone care? */
59 	spin_lock_irqsave(&ev_int->wait.lock, flags);
60 	if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
61 
62 		ev.id = ev_code;
63 		ev.timestamp = timestamp;
64 
65 		copied = kfifo_put(&ev_int->det_events, ev);
66 		if (copied != 0)
67 			wake_up_locked_poll(&ev_int->wait, POLLIN);
68 	}
69 	spin_unlock_irqrestore(&ev_int->wait.lock, flags);
70 
71 	return 0;
72 }
73 EXPORT_SYMBOL(iio_push_event);
74 
75 /**
76  * iio_event_poll() - poll the event queue to find out if it has data
77  */
78 static unsigned int iio_event_poll(struct file *filep,
79 			     struct poll_table_struct *wait)
80 {
81 	struct iio_dev *indio_dev = filep->private_data;
82 	struct iio_event_interface *ev_int = indio_dev->event_interface;
83 	unsigned int events = 0;
84 
85 	if (!indio_dev->info)
86 		return -ENODEV;
87 
88 	poll_wait(filep, &ev_int->wait, wait);
89 
90 	spin_lock_irq(&ev_int->wait.lock);
91 	if (!kfifo_is_empty(&ev_int->det_events))
92 		events = POLLIN | POLLRDNORM;
93 	spin_unlock_irq(&ev_int->wait.lock);
94 
95 	return events;
96 }
97 
98 static ssize_t iio_event_chrdev_read(struct file *filep,
99 				     char __user *buf,
100 				     size_t count,
101 				     loff_t *f_ps)
102 {
103 	struct iio_dev *indio_dev = filep->private_data;
104 	struct iio_event_interface *ev_int = indio_dev->event_interface;
105 	unsigned int copied;
106 	int ret;
107 
108 	if (!indio_dev->info)
109 		return -ENODEV;
110 
111 	if (count < sizeof(struct iio_event_data))
112 		return -EINVAL;
113 
114 	spin_lock_irq(&ev_int->wait.lock);
115 	if (kfifo_is_empty(&ev_int->det_events)) {
116 		if (filep->f_flags & O_NONBLOCK) {
117 			ret = -EAGAIN;
118 			goto error_unlock;
119 		}
120 		/* Blocking on device; waiting for something to be there */
121 		ret = wait_event_interruptible_locked_irq(ev_int->wait,
122 					!kfifo_is_empty(&ev_int->det_events) ||
123 					indio_dev->info == NULL);
124 		if (ret)
125 			goto error_unlock;
126 		if (indio_dev->info == NULL) {
127 			ret = -ENODEV;
128 			goto error_unlock;
129 		}
130 		/* Single access device so no one else can get the data */
131 	}
132 
133 	ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
134 
135 error_unlock:
136 	spin_unlock_irq(&ev_int->wait.lock);
137 
138 	return ret ? ret : copied;
139 }
140 
141 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
142 {
143 	struct iio_dev *indio_dev = filep->private_data;
144 	struct iio_event_interface *ev_int = indio_dev->event_interface;
145 
146 	spin_lock_irq(&ev_int->wait.lock);
147 	__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
148 	/*
149 	 * In order to maintain a clean state for reopening,
150 	 * clear out any awaiting events. The mask will prevent
151 	 * any new __iio_push_event calls running.
152 	 */
153 	kfifo_reset_out(&ev_int->det_events);
154 	spin_unlock_irq(&ev_int->wait.lock);
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 	spin_lock_irq(&ev_int->wait.lock);
178 	if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
179 		spin_unlock_irq(&ev_int->wait.lock);
180 		return -EBUSY;
181 	}
182 	spin_unlock_irq(&ev_int->wait.lock);
183 	iio_device_get(indio_dev);
184 
185 	fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
186 				indio_dev, O_RDONLY | O_CLOEXEC);
187 	if (fd < 0) {
188 		spin_lock_irq(&ev_int->wait.lock);
189 		__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
190 		spin_unlock_irq(&ev_int->wait.lock);
191 		iio_device_put(indio_dev);
192 	}
193 	return fd;
194 }
195 
196 static const char * const iio_ev_type_text[] = {
197 	[IIO_EV_TYPE_THRESH] = "thresh",
198 	[IIO_EV_TYPE_MAG] = "mag",
199 	[IIO_EV_TYPE_ROC] = "roc",
200 	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
201 	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
202 };
203 
204 static const char * const iio_ev_dir_text[] = {
205 	[IIO_EV_DIR_EITHER] = "either",
206 	[IIO_EV_DIR_RISING] = "rising",
207 	[IIO_EV_DIR_FALLING] = "falling"
208 };
209 
210 static const char * const iio_ev_info_text[] = {
211 	[IIO_EV_INFO_ENABLE] = "en",
212 	[IIO_EV_INFO_VALUE] = "value",
213 	[IIO_EV_INFO_HYSTERESIS] = "hysteresis",
214 };
215 
216 static 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 
221 static 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 
226 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
227 {
228 	return (attr->address >> 16) & 0xffff;
229 }
230 
231 static 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 
252 static 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 
269 static 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;
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 	return iio_format_value(buf, ret, val, val2);
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)) {
327 		postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
328 				iio_ev_type_text[type], iio_ev_dir_text[dir],
329 				iio_ev_info_text[i]);
330 		if (postfix == NULL)
331 			return -ENOMEM;
332 
333 		if (i == IIO_EV_INFO_ENABLE) {
334 			show = iio_ev_state_show;
335 			store = iio_ev_state_store;
336 		} else {
337 			show = iio_ev_value_show;
338 			store = iio_ev_value_store;
339 		}
340 
341 		ret = __iio_add_chan_devattr(postfix, chan, show, store,
342 			 (i << 16) | spec_index, shared_by, &indio_dev->dev,
343 			&indio_dev->event_interface->dev_attr_list);
344 		kfree(postfix);
345 
346 		if (ret)
347 			return ret;
348 
349 		attrcount++;
350 	}
351 
352 	return attrcount;
353 }
354 
355 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
356 	struct iio_chan_spec const *chan)
357 {
358 	int ret = 0, i, attrcount = 0;
359 	enum iio_event_direction dir;
360 	enum iio_event_type type;
361 
362 	for (i = 0; i < chan->num_event_specs; i++) {
363 		type = chan->event_spec[i].type;
364 		dir = chan->event_spec[i].dir;
365 
366 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
367 			IIO_SEPARATE, &chan->event_spec[i].mask_separate);
368 		if (ret < 0)
369 			goto error_ret;
370 		attrcount += ret;
371 
372 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
373 			IIO_SHARED_BY_TYPE,
374 			&chan->event_spec[i].mask_shared_by_type);
375 		if (ret < 0)
376 			goto error_ret;
377 		attrcount += ret;
378 
379 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
380 			IIO_SHARED_BY_DIR,
381 			&chan->event_spec[i].mask_shared_by_dir);
382 		if (ret < 0)
383 			goto error_ret;
384 		attrcount += ret;
385 
386 		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
387 			IIO_SHARED_BY_ALL,
388 			&chan->event_spec[i].mask_shared_by_all);
389 		if (ret < 0)
390 			goto error_ret;
391 		attrcount += ret;
392 	}
393 	ret = attrcount;
394 error_ret:
395 	return ret;
396 }
397 
398 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
399 {
400 	int j, ret, attrcount = 0;
401 
402 	/* Dynically created from the channels array */
403 	for (j = 0; j < indio_dev->num_channels; j++) {
404 		ret = iio_device_add_event_sysfs(indio_dev,
405 						 &indio_dev->channels[j]);
406 		if (ret < 0)
407 			return ret;
408 		attrcount += ret;
409 	}
410 	return attrcount;
411 }
412 
413 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
414 {
415 	int j;
416 
417 	for (j = 0; j < indio_dev->num_channels; j++) {
418 		if (indio_dev->channels[j].num_event_specs != 0)
419 			return true;
420 	}
421 	return false;
422 }
423 
424 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
425 {
426 	INIT_KFIFO(ev_int->det_events);
427 	init_waitqueue_head(&ev_int->wait);
428 }
429 
430 static const char *iio_event_group_name = "events";
431 int iio_device_register_eventset(struct iio_dev *indio_dev)
432 {
433 	struct iio_dev_attr *p;
434 	int ret = 0, attrcount_orig = 0, attrcount, attrn;
435 	struct attribute **attr;
436 
437 	if (!(indio_dev->info->event_attrs ||
438 	      iio_check_for_dynamic_events(indio_dev)))
439 		return 0;
440 
441 	indio_dev->event_interface =
442 		kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
443 	if (indio_dev->event_interface == NULL) {
444 		ret = -ENOMEM;
445 		goto error_ret;
446 	}
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 error_ret:
493 
494 	return ret;
495 }
496 
497 /**
498  * iio_device_wakeup_eventset - Wakes up the event waitqueue
499  * @indio_dev: The IIO device
500  *
501  * Wakes up the event waitqueue used for poll() and blocking read().
502  * Should usually be called when the device is unregistered.
503  */
504 void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
505 {
506 	if (indio_dev->event_interface == NULL)
507 		return;
508 	wake_up(&indio_dev->event_interface->wait);
509 }
510 
511 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
512 {
513 	if (indio_dev->event_interface == NULL)
514 		return;
515 	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
516 	kfree(indio_dev->event_interface->group.attrs);
517 	kfree(indio_dev->event_interface);
518 }
519