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industrialio-event.c
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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 
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 
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 }
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