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 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
46 {
47 	struct iio_event_interface *ev_int = indio_dev->event_interface;
48 	struct iio_event_data ev;
49 	unsigned long flags;
50 	int copied;
51 
52 	/* Does anyone care? */
53 	spin_lock_irqsave(&ev_int->wait.lock, flags);
54 	if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
55 
56 		ev.id = ev_code;
57 		ev.timestamp = timestamp;
58 
59 		copied = kfifo_put(&ev_int->det_events, &ev);
60 		if (copied != 0)
61 			wake_up_locked_poll(&ev_int->wait, POLLIN);
62 	}
63 	spin_unlock_irqrestore(&ev_int->wait.lock, flags);
64 
65 	return 0;
66 }
67 EXPORT_SYMBOL(iio_push_event);
68 
69 /**
70  * iio_event_poll() - poll the event queue to find out if it has data
71  */
72 static unsigned int iio_event_poll(struct file *filep,
73 			     struct poll_table_struct *wait)
74 {
75 	struct iio_dev *indio_dev = filep->private_data;
76 	struct iio_event_interface *ev_int = indio_dev->event_interface;
77 	unsigned int events = 0;
78 
79 	poll_wait(filep, &ev_int->wait, wait);
80 
81 	spin_lock_irq(&ev_int->wait.lock);
82 	if (!kfifo_is_empty(&ev_int->det_events))
83 		events = POLLIN | POLLRDNORM;
84 	spin_unlock_irq(&ev_int->wait.lock);
85 
86 	return events;
87 }
88 
89 static ssize_t iio_event_chrdev_read(struct file *filep,
90 				     char __user *buf,
91 				     size_t count,
92 				     loff_t *f_ps)
93 {
94 	struct iio_dev *indio_dev = filep->private_data;
95 	struct iio_event_interface *ev_int = indio_dev->event_interface;
96 	unsigned int copied;
97 	int ret;
98 
99 	if (count < sizeof(struct iio_event_data))
100 		return -EINVAL;
101 
102 	spin_lock_irq(&ev_int->wait.lock);
103 	if (kfifo_is_empty(&ev_int->det_events)) {
104 		if (filep->f_flags & O_NONBLOCK) {
105 			ret = -EAGAIN;
106 			goto error_unlock;
107 		}
108 		/* Blocking on device; waiting for something to be there */
109 		ret = wait_event_interruptible_locked_irq(ev_int->wait,
110 					!kfifo_is_empty(&ev_int->det_events));
111 		if (ret)
112 			goto error_unlock;
113 		/* Single access device so no one else can get the data */
114 	}
115 
116 	ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
117 
118 error_unlock:
119 	spin_unlock_irq(&ev_int->wait.lock);
120 
121 	return ret ? ret : copied;
122 }
123 
124 static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
125 {
126 	struct iio_dev *indio_dev = filep->private_data;
127 	struct iio_event_interface *ev_int = indio_dev->event_interface;
128 
129 	spin_lock_irq(&ev_int->wait.lock);
130 	__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
131 	/*
132 	 * In order to maintain a clean state for reopening,
133 	 * clear out any awaiting events. The mask will prevent
134 	 * any new __iio_push_event calls running.
135 	 */
136 	kfifo_reset_out(&ev_int->det_events);
137 	spin_unlock_irq(&ev_int->wait.lock);
138 
139 	iio_device_put(indio_dev);
140 
141 	return 0;
142 }
143 
144 static const struct file_operations iio_event_chrdev_fileops = {
145 	.read =  iio_event_chrdev_read,
146 	.poll =  iio_event_poll,
147 	.release = iio_event_chrdev_release,
148 	.owner = THIS_MODULE,
149 	.llseek = noop_llseek,
150 };
151 
152 int iio_event_getfd(struct iio_dev *indio_dev)
153 {
154 	struct iio_event_interface *ev_int = indio_dev->event_interface;
155 	int fd;
156 
157 	if (ev_int == NULL)
158 		return -ENODEV;
159 
160 	spin_lock_irq(&ev_int->wait.lock);
161 	if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
162 		spin_unlock_irq(&ev_int->wait.lock);
163 		return -EBUSY;
164 	}
165 	spin_unlock_irq(&ev_int->wait.lock);
166 	iio_device_get(indio_dev);
167 
168 	fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
169 				indio_dev, O_RDONLY);
170 	if (fd < 0) {
171 		spin_lock_irq(&ev_int->wait.lock);
172 		__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
173 		spin_unlock_irq(&ev_int->wait.lock);
174 		iio_device_put(indio_dev);
175 	}
176 	return fd;
177 }
178 
179 static const char * const iio_ev_type_text[] = {
180 	[IIO_EV_TYPE_THRESH] = "thresh",
181 	[IIO_EV_TYPE_MAG] = "mag",
182 	[IIO_EV_TYPE_ROC] = "roc",
183 	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
184 	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
185 };
186 
187 static const char * const iio_ev_dir_text[] = {
188 	[IIO_EV_DIR_EITHER] = "either",
189 	[IIO_EV_DIR_RISING] = "rising",
190 	[IIO_EV_DIR_FALLING] = "falling"
191 };
192 
193 static ssize_t iio_ev_state_store(struct device *dev,
194 				  struct device_attribute *attr,
195 				  const char *buf,
196 				  size_t len)
197 {
198 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
199 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
200 	int ret;
201 	bool val;
202 
203 	ret = strtobool(buf, &val);
204 	if (ret < 0)
205 		return ret;
206 
207 	ret = indio_dev->info->write_event_config(indio_dev,
208 						  this_attr->address,
209 						  val);
210 	return (ret < 0) ? ret : len;
211 }
212 
213 static ssize_t iio_ev_state_show(struct device *dev,
214 				 struct device_attribute *attr,
215 				 char *buf)
216 {
217 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
218 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
219 	int val = indio_dev->info->read_event_config(indio_dev,
220 						     this_attr->address);
221 
222 	if (val < 0)
223 		return val;
224 	else
225 		return sprintf(buf, "%d\n", val);
226 }
227 
228 static ssize_t iio_ev_value_show(struct device *dev,
229 				 struct device_attribute *attr,
230 				 char *buf)
231 {
232 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
233 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
234 	int val, ret;
235 
236 	ret = indio_dev->info->read_event_value(indio_dev,
237 						this_attr->address, &val);
238 	if (ret < 0)
239 		return ret;
240 
241 	return sprintf(buf, "%d\n", val);
242 }
243 
244 static ssize_t iio_ev_value_store(struct device *dev,
245 				  struct device_attribute *attr,
246 				  const char *buf,
247 				  size_t len)
248 {
249 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
250 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
251 	int val;
252 	int ret;
253 
254 	if (!indio_dev->info->write_event_value)
255 		return -EINVAL;
256 
257 	ret = kstrtoint(buf, 10, &val);
258 	if (ret)
259 		return ret;
260 
261 	ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
262 						 val);
263 	if (ret < 0)
264 		return ret;
265 
266 	return len;
267 }
268 
269 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
270 				      struct iio_chan_spec const *chan)
271 {
272 	int ret = 0, i, attrcount = 0;
273 	u64 mask = 0;
274 	char *postfix;
275 	if (!chan->event_mask)
276 		return 0;
277 
278 	for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
279 		postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
280 				    iio_ev_type_text[i/IIO_EV_DIR_MAX],
281 				    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
282 		if (postfix == NULL) {
283 			ret = -ENOMEM;
284 			goto error_ret;
285 		}
286 		if (chan->modified)
287 			mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel2,
288 						  i/IIO_EV_DIR_MAX,
289 						  i%IIO_EV_DIR_MAX);
290 		else if (chan->differential)
291 			mask = IIO_EVENT_CODE(chan->type,
292 					      0, 0,
293 					      i%IIO_EV_DIR_MAX,
294 					      i/IIO_EV_DIR_MAX,
295 					      0,
296 					      chan->channel,
297 					      chan->channel2);
298 		else
299 			mask = IIO_UNMOD_EVENT_CODE(chan->type,
300 						    chan->channel,
301 						    i/IIO_EV_DIR_MAX,
302 						    i%IIO_EV_DIR_MAX);
303 
304 		ret = __iio_add_chan_devattr(postfix,
305 					     chan,
306 					     &iio_ev_state_show,
307 					     iio_ev_state_store,
308 					     mask,
309 					     0,
310 					     &indio_dev->dev,
311 					     &indio_dev->event_interface->
312 					     dev_attr_list);
313 		kfree(postfix);
314 		if (ret)
315 			goto error_ret;
316 		attrcount++;
317 		postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
318 				    iio_ev_type_text[i/IIO_EV_DIR_MAX],
319 				    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
320 		if (postfix == NULL) {
321 			ret = -ENOMEM;
322 			goto error_ret;
323 		}
324 		ret = __iio_add_chan_devattr(postfix, chan,
325 					     iio_ev_value_show,
326 					     iio_ev_value_store,
327 					     mask,
328 					     0,
329 					     &indio_dev->dev,
330 					     &indio_dev->event_interface->
331 					     dev_attr_list);
332 		kfree(postfix);
333 		if (ret)
334 			goto error_ret;
335 		attrcount++;
336 	}
337 	ret = attrcount;
338 error_ret:
339 	return ret;
340 }
341 
342 static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
343 {
344 	struct iio_dev_attr *p, *n;
345 	list_for_each_entry_safe(p, n,
346 				 &indio_dev->event_interface->
347 				 dev_attr_list, l) {
348 		kfree(p->dev_attr.attr.name);
349 		kfree(p);
350 	}
351 }
352 
353 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
354 {
355 	int j, ret, attrcount = 0;
356 
357 	/* Dynically created from the channels array */
358 	for (j = 0; j < indio_dev->num_channels; j++) {
359 		ret = iio_device_add_event_sysfs(indio_dev,
360 						 &indio_dev->channels[j]);
361 		if (ret < 0)
362 			return ret;
363 		attrcount += ret;
364 	}
365 	return attrcount;
366 }
367 
368 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
369 {
370 	int j;
371 
372 	for (j = 0; j < indio_dev->num_channels; j++)
373 		if (indio_dev->channels[j].event_mask != 0)
374 			return true;
375 	return false;
376 }
377 
378 static void iio_setup_ev_int(struct iio_event_interface *ev_int)
379 {
380 	INIT_KFIFO(ev_int->det_events);
381 	init_waitqueue_head(&ev_int->wait);
382 }
383 
384 static const char *iio_event_group_name = "events";
385 int iio_device_register_eventset(struct iio_dev *indio_dev)
386 {
387 	struct iio_dev_attr *p;
388 	int ret = 0, attrcount_orig = 0, attrcount, attrn;
389 	struct attribute **attr;
390 
391 	if (!(indio_dev->info->event_attrs ||
392 	      iio_check_for_dynamic_events(indio_dev)))
393 		return 0;
394 
395 	indio_dev->event_interface =
396 		kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
397 	if (indio_dev->event_interface == NULL) {
398 		ret = -ENOMEM;
399 		goto error_ret;
400 	}
401 
402 	INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
403 
404 	iio_setup_ev_int(indio_dev->event_interface);
405 	if (indio_dev->info->event_attrs != NULL) {
406 		attr = indio_dev->info->event_attrs->attrs;
407 		while (*attr++ != NULL)
408 			attrcount_orig++;
409 	}
410 	attrcount = attrcount_orig;
411 	if (indio_dev->channels) {
412 		ret = __iio_add_event_config_attrs(indio_dev);
413 		if (ret < 0)
414 			goto error_free_setup_event_lines;
415 		attrcount += ret;
416 	}
417 
418 	indio_dev->event_interface->group.name = iio_event_group_name;
419 	indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
420 							  sizeof(indio_dev->event_interface->group.attrs[0]),
421 							  GFP_KERNEL);
422 	if (indio_dev->event_interface->group.attrs == NULL) {
423 		ret = -ENOMEM;
424 		goto error_free_setup_event_lines;
425 	}
426 	if (indio_dev->info->event_attrs)
427 		memcpy(indio_dev->event_interface->group.attrs,
428 		       indio_dev->info->event_attrs->attrs,
429 		       sizeof(indio_dev->event_interface->group.attrs[0])
430 		       *attrcount_orig);
431 	attrn = attrcount_orig;
432 	/* Add all elements from the list. */
433 	list_for_each_entry(p,
434 			    &indio_dev->event_interface->dev_attr_list,
435 			    l)
436 		indio_dev->event_interface->group.attrs[attrn++] =
437 			&p->dev_attr.attr;
438 	indio_dev->groups[indio_dev->groupcounter++] =
439 		&indio_dev->event_interface->group;
440 
441 	return 0;
442 
443 error_free_setup_event_lines:
444 	__iio_remove_event_config_attrs(indio_dev);
445 	kfree(indio_dev->event_interface);
446 error_ret:
447 
448 	return ret;
449 }
450 
451 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
452 {
453 	if (indio_dev->event_interface == NULL)
454 		return;
455 	__iio_remove_event_config_attrs(indio_dev);
456 	kfree(indio_dev->event_interface->group.attrs);
457 	kfree(indio_dev->event_interface);
458 }
459