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 * @read_lock: lock to protect kfifo read operations
36 */
37struct iio_event_interface {
38 wait_queue_head_t wait;
39 DECLARE_KFIFO(det_events, struct iio_event_data, 16);
40
41 struct list_head dev_attr_list;
42 unsigned long flags;
43 struct attribute_group group;
44 struct mutex read_lock;
45};
46
47bool iio_event_enabled(const struct iio_event_interface *ev_int)
48{
49 return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
50}
51
52/**
53 * iio_push_event() - try to add event to the list for userspace reading
54 * @indio_dev: IIO device structure
55 * @ev_code: What event
56 * @timestamp: When the event occurred
57 *
58 * Note: The caller must make sure that this function is not running
59 * concurrently for the same indio_dev more than once.
60 *
61 * This function may be safely used as soon as a valid reference to iio_dev has
62 * been obtained via iio_device_alloc(), but any events that are submitted
63 * before iio_device_register() has successfully completed will be silently
64 * discarded.
65 **/
66int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
67{
68 struct iio_event_interface *ev_int = indio_dev->event_interface;
69 struct iio_event_data ev;
70 int copied;
71
72 if (!ev_int)
73 return 0;
74
75 /* Does anyone care? */
76 if (iio_event_enabled(ev_int)) {
77
78 ev.id = ev_code;
79 ev.timestamp = timestamp;
80
81 copied = kfifo_put(&ev_int->det_events, ev);
82 if (copied != 0)
83 wake_up_poll(&ev_int->wait, EPOLLIN);
84 }
85
86 return 0;
87}
88EXPORT_SYMBOL(iio_push_event);
89
90/**
91 * iio_event_poll() - poll the event queue to find out if it has data
92 * @filep: File structure pointer to identify the device
93 * @wait: Poll table pointer to add the wait queue on
94 *
95 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
96 * or a negative error code on failure
97 */
98static __poll_t iio_event_poll(struct file *filep,
99 struct poll_table_struct *wait)
100{
101 struct iio_dev *indio_dev = filep->private_data;
102 struct iio_event_interface *ev_int = indio_dev->event_interface;
103 __poll_t events = 0;
104
105 if (!indio_dev->info)
106 return events;
107
108 poll_wait(filep, &ev_int->wait, wait);
109
110 if (!kfifo_is_empty(&ev_int->det_events))
111 events = EPOLLIN | EPOLLRDNORM;
112
113 return events;
114}
115
116static ssize_t iio_event_chrdev_read(struct file *filep,
117 char __user *buf,
118 size_t count,
119 loff_t *f_ps)
120{
121 struct iio_dev *indio_dev = filep->private_data;
122 struct iio_event_interface *ev_int = indio_dev->event_interface;
123 unsigned int copied;
124 int ret;
125
126 if (!indio_dev->info)
127 return -ENODEV;
128
129 if (count < sizeof(struct iio_event_data))
130 return -EINVAL;
131
132 do {
133 if (kfifo_is_empty(&ev_int->det_events)) {
134 if (filep->f_flags & O_NONBLOCK)
135 return -EAGAIN;
136
137 ret = wait_event_interruptible(ev_int->wait,
138 !kfifo_is_empty(&ev_int->det_events) ||
139 indio_dev->info == NULL);
140 if (ret)
141 return ret;
142 if (indio_dev->info == NULL)
143 return -ENODEV;
144 }
145
146 if (mutex_lock_interruptible(&ev_int->read_lock))
147 return -ERESTARTSYS;
148 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
149 mutex_unlock(&ev_int->read_lock);
150
151 if (ret)
152 return ret;
153
154 /*
155 * If we couldn't read anything from the fifo (a different
156 * thread might have been faster) we either return -EAGAIN if
157 * the file descriptor is non-blocking, otherwise we go back to
158 * sleep and wait for more data to arrive.
159 */
160 if (copied == 0 && (filep->f_flags & O_NONBLOCK))
161 return -EAGAIN;
162
163 } while (copied == 0);
164
165 return copied;
166}
167
168static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
169{
170 struct iio_dev *indio_dev = filep->private_data;
171 struct iio_event_interface *ev_int = indio_dev->event_interface;
172
173 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
174
175 iio_device_put(indio_dev);
176
177 return 0;
178}
179
180static const struct file_operations iio_event_chrdev_fileops = {
181 .read = iio_event_chrdev_read,
182 .poll = iio_event_poll,
183 .release = iio_event_chrdev_release,
184 .owner = THIS_MODULE,
185 .llseek = noop_llseek,
186};
187
188int iio_event_getfd(struct iio_dev *indio_dev)
189{
190 struct iio_event_interface *ev_int = indio_dev->event_interface;
191 int fd;
192
193 if (ev_int == NULL)
194 return -ENODEV;
195
196 fd = mutex_lock_interruptible(&indio_dev->mlock);
197 if (fd)
198 return fd;
199
200 if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
201 fd = -EBUSY;
202 goto unlock;
203 }
204
205 iio_device_get(indio_dev);
206
207 fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
208 indio_dev, O_RDONLY | O_CLOEXEC);
209 if (fd < 0) {
210 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
211 iio_device_put(indio_dev);
212 } else {
213 kfifo_reset_out(&ev_int->det_events);
214 }
215
216unlock:
217 mutex_unlock(&indio_dev->mlock);
218 return fd;
219}
220
221static const char * const iio_ev_type_text[] = {
222 [IIO_EV_TYPE_THRESH] = "thresh",
223 [IIO_EV_TYPE_MAG] = "mag",
224 [IIO_EV_TYPE_ROC] = "roc",
225 [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
226 [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
227 [IIO_EV_TYPE_CHANGE] = "change",
228};
229
230static const char * const iio_ev_dir_text[] = {
231 [IIO_EV_DIR_EITHER] = "either",
232 [IIO_EV_DIR_RISING] = "rising",
233 [IIO_EV_DIR_FALLING] = "falling"
234};
235
236static const char * const iio_ev_info_text[] = {
237 [IIO_EV_INFO_ENABLE] = "en",
238 [IIO_EV_INFO_VALUE] = "value",
239 [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
240 [IIO_EV_INFO_PERIOD] = "period",
241 [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
242 [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
243};
244
245static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
246{
247 return attr->c->event_spec[attr->address & 0xffff].dir;
248}
249
250static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
251{
252 return attr->c->event_spec[attr->address & 0xffff].type;
253}
254
255static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
256{
257 return (attr->address >> 16) & 0xffff;
258}
259
260static ssize_t iio_ev_state_store(struct device *dev,
261 struct device_attribute *attr,
262 const char *buf,
263 size_t len)
264{
265 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
266 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
267 int ret;
268 bool val;
269
270 ret = strtobool(buf, &val);
271 if (ret < 0)
272 return ret;
273
274 ret = indio_dev->info->write_event_config(indio_dev,
275 this_attr->c, iio_ev_attr_type(this_attr),
276 iio_ev_attr_dir(this_attr), val);
277
278 return (ret < 0) ? ret : len;
279}
280
281static ssize_t iio_ev_state_show(struct device *dev,
282 struct device_attribute *attr,
283 char *buf)
284{
285 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
286 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
287 int val;
288
289 val = indio_dev->info->read_event_config(indio_dev,
290 this_attr->c, iio_ev_attr_type(this_attr),
291 iio_ev_attr_dir(this_attr));
292 if (val < 0)
293 return val;
294 else
295 return sprintf(buf, "%d\n", val);
296}
297
298static ssize_t iio_ev_value_show(struct device *dev,
299 struct device_attribute *attr,
300 char *buf)
301{
302 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
303 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
304 int val, val2, val_arr[2];
305 int ret;
306
307 ret = indio_dev->info->read_event_value(indio_dev,
308 this_attr->c, iio_ev_attr_type(this_attr),
309 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
310 &val, &val2);
311 if (ret < 0)
312 return ret;
313 val_arr[0] = val;
314 val_arr[1] = val2;
315 return iio_format_value(buf, ret, 2, val_arr);
316}
317
318static ssize_t iio_ev_value_store(struct device *dev,
319 struct device_attribute *attr,
320 const char *buf,
321 size_t len)
322{
323 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
324 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
325 int val, val2;
326 int ret;
327
328 if (!indio_dev->info->write_event_value)
329 return -EINVAL;
330
331 ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
332 if (ret)
333 return ret;
334 ret = indio_dev->info->write_event_value(indio_dev,
335 this_attr->c, iio_ev_attr_type(this_attr),
336 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
337 val, val2);
338 if (ret < 0)
339 return ret;
340
341 return len;
342}
343
344static int iio_device_add_event(struct iio_dev *indio_dev,
345 const struct iio_chan_spec *chan, unsigned int spec_index,
346 enum iio_event_type type, enum iio_event_direction dir,
347 enum iio_shared_by shared_by, const unsigned long *mask)
348{
349 ssize_t (*show)(struct device *, struct device_attribute *, char *);
350 ssize_t (*store)(struct device *, struct device_attribute *,
351 const char *, size_t);
352 unsigned int attrcount = 0;
353 unsigned int i;
354 char *postfix;
355 int ret;
356
357 for_each_set_bit(i, mask, sizeof(*mask)*8) {
358 if (i >= ARRAY_SIZE(iio_ev_info_text))
359 return -EINVAL;
360 if (dir != IIO_EV_DIR_NONE)
361 postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
362 iio_ev_type_text[type],
363 iio_ev_dir_text[dir],
364 iio_ev_info_text[i]);
365 else
366 postfix = kasprintf(GFP_KERNEL, "%s_%s",
367 iio_ev_type_text[type],
368 iio_ev_info_text[i]);
369 if (postfix == NULL)
370 return -ENOMEM;
371
372 if (i == IIO_EV_INFO_ENABLE) {
373 show = iio_ev_state_show;
374 store = iio_ev_state_store;
375 } else {
376 show = iio_ev_value_show;
377 store = iio_ev_value_store;
378 }
379
380 ret = __iio_add_chan_devattr(postfix, chan, show, store,
381 (i << 16) | spec_index, shared_by, &indio_dev->dev,
382 &indio_dev->event_interface->dev_attr_list);
383 kfree(postfix);
384
385 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
386 continue;
387
388 if (ret)
389 return ret;
390
391 attrcount++;
392 }
393
394 return attrcount;
395}
396
397static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
398 struct iio_chan_spec const *chan)
399{
400 int ret = 0, i, attrcount = 0;
401 enum iio_event_direction dir;
402 enum iio_event_type type;
403
404 for (i = 0; i < chan->num_event_specs; i++) {
405 type = chan->event_spec[i].type;
406 dir = chan->event_spec[i].dir;
407
408 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
409 IIO_SEPARATE, &chan->event_spec[i].mask_separate);
410 if (ret < 0)
411 return ret;
412 attrcount += ret;
413
414 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
415 IIO_SHARED_BY_TYPE,
416 &chan->event_spec[i].mask_shared_by_type);
417 if (ret < 0)
418 return ret;
419 attrcount += ret;
420
421 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
422 IIO_SHARED_BY_DIR,
423 &chan->event_spec[i].mask_shared_by_dir);
424 if (ret < 0)
425 return ret;
426 attrcount += ret;
427
428 ret = iio_device_add_event(indio_dev, chan, i, type, dir,
429 IIO_SHARED_BY_ALL,
430 &chan->event_spec[i].mask_shared_by_all);
431 if (ret < 0)
432 return ret;
433 attrcount += ret;
434 }
435 ret = attrcount;
436 return ret;
437}
438
439static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
440{
441 int j, ret, attrcount = 0;
442
443 /* Dynamically created from the channels array */
444 for (j = 0; j < indio_dev->num_channels; j++) {
445 ret = iio_device_add_event_sysfs(indio_dev,
446 &indio_dev->channels[j]);
447 if (ret < 0)
448 return ret;
449 attrcount += ret;
450 }
451 return attrcount;
452}
453
454static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
455{
456 int j;
457
458 for (j = 0; j < indio_dev->num_channels; j++) {
459 if (indio_dev->channels[j].num_event_specs != 0)
460 return true;
461 }
462 return false;
463}
464
465static void iio_setup_ev_int(struct iio_event_interface *ev_int)
466{
467 INIT_KFIFO(ev_int->det_events);
468 init_waitqueue_head(&ev_int->wait);
469 mutex_init(&ev_int->read_lock);
470}
471
472static const char *iio_event_group_name = "events";
473int iio_device_register_eventset(struct iio_dev *indio_dev)
474{
475 struct iio_dev_attr *p;
476 int ret = 0, attrcount_orig = 0, attrcount, attrn;
477 struct attribute **attr;
478
479 if (!(indio_dev->info->event_attrs ||
480 iio_check_for_dynamic_events(indio_dev)))
481 return 0;
482
483 indio_dev->event_interface =
484 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
485 if (indio_dev->event_interface == NULL)
486 return -ENOMEM;
487
488 INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
489
490 iio_setup_ev_int(indio_dev->event_interface);
491 if (indio_dev->info->event_attrs != NULL) {
492 attr = indio_dev->info->event_attrs->attrs;
493 while (*attr++ != NULL)
494 attrcount_orig++;
495 }
496 attrcount = attrcount_orig;
497 if (indio_dev->channels) {
498 ret = __iio_add_event_config_attrs(indio_dev);
499 if (ret < 0)
500 goto error_free_setup_event_lines;
501 attrcount += ret;
502 }
503
504 indio_dev->event_interface->group.name = iio_event_group_name;
505 indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
506 sizeof(indio_dev->event_interface->group.attrs[0]),
507 GFP_KERNEL);
508 if (indio_dev->event_interface->group.attrs == NULL) {
509 ret = -ENOMEM;
510 goto error_free_setup_event_lines;
511 }
512 if (indio_dev->info->event_attrs)
513 memcpy(indio_dev->event_interface->group.attrs,
514 indio_dev->info->event_attrs->attrs,
515 sizeof(indio_dev->event_interface->group.attrs[0])
516 *attrcount_orig);
517 attrn = attrcount_orig;
518 /* Add all elements from the list. */
519 list_for_each_entry(p,
520 &indio_dev->event_interface->dev_attr_list,
521 l)
522 indio_dev->event_interface->group.attrs[attrn++] =
523 &p->dev_attr.attr;
524 indio_dev->groups[indio_dev->groupcounter++] =
525 &indio_dev->event_interface->group;
526
527 return 0;
528
529error_free_setup_event_lines:
530 iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
531 kfree(indio_dev->event_interface);
532 indio_dev->event_interface = NULL;
533 return ret;
534}
535
536/**
537 * iio_device_wakeup_eventset - Wakes up the event waitqueue
538 * @indio_dev: The IIO device
539 *
540 * Wakes up the event waitqueue used for poll() and blocking read().
541 * Should usually be called when the device is unregistered.
542 */
543void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
544{
545 if (indio_dev->event_interface == NULL)
546 return;
547 wake_up(&indio_dev->event_interface->wait);
548}
549
550void iio_device_unregister_eventset(struct iio_dev *indio_dev)
551{
552 if (indio_dev->event_interface == NULL)
553 return;
554 iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
555 kfree(indio_dev->event_interface->group.attrs);
556 kfree(indio_dev->event_interface);
557}
558