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