1/* The industrial I/O core, trigger handling functions
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
10#include <linux/kernel.h>
11#include <linux/idr.h>
12#include <linux/err.h>
13#include <linux/device.h>
14#include <linux/interrupt.h>
15#include <linux/list.h>
16#include <linux/slab.h>
17
18#include <linux/iio/iio.h>
19#include <linux/iio/trigger.h>
20#include "iio_core.h"
21#include "iio_core_trigger.h"
22#include <linux/iio/trigger_consumer.h>
23
24/* RFC - Question of approach
25 * Make the common case (single sensor single trigger)
26 * simple by starting trigger capture from when first sensors
27 * is added.
28 *
29 * Complex simultaneous start requires use of 'hold' functionality
30 * of the trigger. (not implemented)
31 *
32 * Any other suggestions?
33 */
34
35static DEFINE_IDA(iio_trigger_ida);
36
37/* Single list of all available triggers */
38static LIST_HEAD(iio_trigger_list);
39static DEFINE_MUTEX(iio_trigger_list_lock);
40
41/**
42 * iio_trigger_read_name() - retrieve useful identifying name
43 * @dev:	device associated with the iio_trigger
44 * @attr:	pointer to the device_attribute structure that is
45 *		being processed
46 * @buf:	buffer to print the name into
47 *
48 * Return: a negative number on failure or the number of written
49 *	   characters on success.
50 */
51static ssize_t iio_trigger_read_name(struct device *dev,
52				     struct device_attribute *attr,
53				     char *buf)
54{
55	struct iio_trigger *trig = to_iio_trigger(dev);
56	return sprintf(buf, "%s\n", trig->name);
57}
58
59static DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);
60
61static struct attribute *iio_trig_dev_attrs[] = {
62	&dev_attr_name.attr,
63	NULL,
64};
65ATTRIBUTE_GROUPS(iio_trig_dev);
66
67int iio_trigger_register(struct iio_trigger *trig_info)
68{
69	int ret;
70
71	trig_info->id = ida_simple_get(&iio_trigger_ida, 0, 0, GFP_KERNEL);
72	if (trig_info->id < 0)
73		return trig_info->id;
74
75	/* Set the name used for the sysfs directory etc */
76	dev_set_name(&trig_info->dev, "trigger%ld",
77		     (unsigned long) trig_info->id);
78
79	ret = device_add(&trig_info->dev);
80	if (ret)
81		goto error_unregister_id;
82
83	/* Add to list of available triggers held by the IIO core */
84	mutex_lock(&iio_trigger_list_lock);
85	list_add_tail(&trig_info->list, &iio_trigger_list);
86	mutex_unlock(&iio_trigger_list_lock);
87
88	return 0;
89
90error_unregister_id:
91	ida_simple_remove(&iio_trigger_ida, trig_info->id);
92	return ret;
93}
94EXPORT_SYMBOL(iio_trigger_register);
95
96void iio_trigger_unregister(struct iio_trigger *trig_info)
97{
98	mutex_lock(&iio_trigger_list_lock);
99	list_del(&trig_info->list);
100	mutex_unlock(&iio_trigger_list_lock);
101
102	ida_simple_remove(&iio_trigger_ida, trig_info->id);
103	/* Possible issue in here */
104	device_del(&trig_info->dev);
105}
106EXPORT_SYMBOL(iio_trigger_unregister);
107
108static struct iio_trigger *iio_trigger_find_by_name(const char *name,
109						    size_t len)
110{
111	struct iio_trigger *trig = NULL, *iter;
112
113	mutex_lock(&iio_trigger_list_lock);
114	list_for_each_entry(iter, &iio_trigger_list, list)
115		if (sysfs_streq(iter->name, name)) {
116			trig = iter;
117			break;
118		}
119	mutex_unlock(&iio_trigger_list_lock);
120
121	return trig;
122}
123
124void iio_trigger_poll(struct iio_trigger *trig)
125{
126	int i;
127
128	if (!atomic_read(&trig->use_count)) {
129		atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
130
131		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
132			if (trig->subirqs[i].enabled)
133				generic_handle_irq(trig->subirq_base + i);
134			else
135				iio_trigger_notify_done(trig);
136		}
137	}
138}
139EXPORT_SYMBOL(iio_trigger_poll);
140
141irqreturn_t iio_trigger_generic_data_rdy_poll(int irq, void *private)
142{
143	iio_trigger_poll(private);
144	return IRQ_HANDLED;
145}
146EXPORT_SYMBOL(iio_trigger_generic_data_rdy_poll);
147
148void iio_trigger_poll_chained(struct iio_trigger *trig)
149{
150	int i;
151
152	if (!atomic_read(&trig->use_count)) {
153		atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
154
155		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
156			if (trig->subirqs[i].enabled)
157				handle_nested_irq(trig->subirq_base + i);
158			else
159				iio_trigger_notify_done(trig);
160		}
161	}
162}
163EXPORT_SYMBOL(iio_trigger_poll_chained);
164
165void iio_trigger_notify_done(struct iio_trigger *trig)
166{
167	if (atomic_dec_and_test(&trig->use_count) && trig->ops &&
168		trig->ops->try_reenable)
169		if (trig->ops->try_reenable(trig))
170			/* Missed an interrupt so launch new poll now */
171			iio_trigger_poll(trig);
172}
173EXPORT_SYMBOL(iio_trigger_notify_done);
174
175/* Trigger Consumer related functions */
176static int iio_trigger_get_irq(struct iio_trigger *trig)
177{
178	int ret;
179	mutex_lock(&trig->pool_lock);
180	ret = bitmap_find_free_region(trig->pool,
181				      CONFIG_IIO_CONSUMERS_PER_TRIGGER,
182				      ilog2(1));
183	mutex_unlock(&trig->pool_lock);
184	if (ret >= 0)
185		ret += trig->subirq_base;
186
187	return ret;
188}
189
190static void iio_trigger_put_irq(struct iio_trigger *trig, int irq)
191{
192	mutex_lock(&trig->pool_lock);
193	clear_bit(irq - trig->subirq_base, trig->pool);
194	mutex_unlock(&trig->pool_lock);
195}
196
197/* Complexity in here.  With certain triggers (datardy) an acknowledgement
198 * may be needed if the pollfuncs do not include the data read for the
199 * triggering device.
200 * This is not currently handled.  Alternative of not enabling trigger unless
201 * the relevant function is in there may be the best option.
202 */
203/* Worth protecting against double additions? */
204static int iio_trigger_attach_poll_func(struct iio_trigger *trig,
205					struct iio_poll_func *pf)
206{
207	int ret = 0;
208	bool notinuse
209		= bitmap_empty(trig->pool, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
210
211	/* Prevent the module from being removed whilst attached to a trigger */
212	__module_get(pf->indio_dev->info->driver_module);
213	pf->irq = iio_trigger_get_irq(trig);
214	ret = request_threaded_irq(pf->irq, pf->h, pf->thread,
215				   pf->type, pf->name,
216				   pf);
217	if (ret < 0) {
218		module_put(pf->indio_dev->info->driver_module);
219		return ret;
220	}
221
222	if (trig->ops && trig->ops->set_trigger_state && notinuse) {
223		ret = trig->ops->set_trigger_state(trig, true);
224		if (ret < 0)
225			module_put(pf->indio_dev->info->driver_module);
226	}
227
228	return ret;
229}
230
231static int iio_trigger_detach_poll_func(struct iio_trigger *trig,
232					 struct iio_poll_func *pf)
233{
234	int ret = 0;
235	bool no_other_users
236		= (bitmap_weight(trig->pool,
237				 CONFIG_IIO_CONSUMERS_PER_TRIGGER)
238		   == 1);
239	if (trig->ops && trig->ops->set_trigger_state && no_other_users) {
240		ret = trig->ops->set_trigger_state(trig, false);
241		if (ret)
242			return ret;
243	}
244	iio_trigger_put_irq(trig, pf->irq);
245	free_irq(pf->irq, pf);
246	module_put(pf->indio_dev->info->driver_module);
247
248	return ret;
249}
250
251irqreturn_t iio_pollfunc_store_time(int irq, void *p)
252{
253	struct iio_poll_func *pf = p;
254	pf->timestamp = iio_get_time_ns();
255	return IRQ_WAKE_THREAD;
256}
257EXPORT_SYMBOL(iio_pollfunc_store_time);
258
259struct iio_poll_func
260*iio_alloc_pollfunc(irqreturn_t (*h)(int irq, void *p),
261		    irqreturn_t (*thread)(int irq, void *p),
262		    int type,
263		    struct iio_dev *indio_dev,
264		    const char *fmt,
265		    ...)
266{
267	va_list vargs;
268	struct iio_poll_func *pf;
269
270	pf = kmalloc(sizeof *pf, GFP_KERNEL);
271	if (pf == NULL)
272		return NULL;
273	va_start(vargs, fmt);
274	pf->name = kvasprintf(GFP_KERNEL, fmt, vargs);
275	va_end(vargs);
276	if (pf->name == NULL) {
277		kfree(pf);
278		return NULL;
279	}
280	pf->h = h;
281	pf->thread = thread;
282	pf->type = type;
283	pf->indio_dev = indio_dev;
284
285	return pf;
286}
287EXPORT_SYMBOL_GPL(iio_alloc_pollfunc);
288
289void iio_dealloc_pollfunc(struct iio_poll_func *pf)
290{
291	kfree(pf->name);
292	kfree(pf);
293}
294EXPORT_SYMBOL_GPL(iio_dealloc_pollfunc);
295
296/**
297 * iio_trigger_read_current() - trigger consumer sysfs query current trigger
298 * @dev:	device associated with an industrial I/O device
299 * @attr:	pointer to the device_attribute structure that
300 *		is being processed
301 * @buf:	buffer where the current trigger name will be printed into
302 *
303 * For trigger consumers the current_trigger interface allows the trigger
304 * used by the device to be queried.
305 *
306 * Return: a negative number on failure, the number of characters written
307 *	   on success or 0 if no trigger is available
308 */
309static ssize_t iio_trigger_read_current(struct device *dev,
310					struct device_attribute *attr,
311					char *buf)
312{
313	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
314
315	if (indio_dev->trig)
316		return sprintf(buf, "%s\n", indio_dev->trig->name);
317	return 0;
318}
319
320/**
321 * iio_trigger_write_current() - trigger consumer sysfs set current trigger
322 * @dev:	device associated with an industrial I/O device
323 * @attr:	device attribute that is being processed
324 * @buf:	string buffer that holds the name of the trigger
325 * @len:	length of the trigger name held by buf
326 *
327 * For trigger consumers the current_trigger interface allows the trigger
328 * used for this device to be specified at run time based on the trigger's
329 * name.
330 *
331 * Return: negative error code on failure or length of the buffer
332 *	   on success
333 */
334static ssize_t iio_trigger_write_current(struct device *dev,
335					 struct device_attribute *attr,
336					 const char *buf,
337					 size_t len)
338{
339	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
340	struct iio_trigger *oldtrig = indio_dev->trig;
341	struct iio_trigger *trig;
342	int ret;
343
344	mutex_lock(&indio_dev->mlock);
345	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
346		mutex_unlock(&indio_dev->mlock);
347		return -EBUSY;
348	}
349	mutex_unlock(&indio_dev->mlock);
350
351	trig = iio_trigger_find_by_name(buf, len);
352	if (oldtrig == trig)
353		return len;
354
355	if (trig && indio_dev->info->validate_trigger) {
356		ret = indio_dev->info->validate_trigger(indio_dev, trig);
357		if (ret)
358			return ret;
359	}
360
361	if (trig && trig->ops && trig->ops->validate_device) {
362		ret = trig->ops->validate_device(trig, indio_dev);
363		if (ret)
364			return ret;
365	}
366
367	indio_dev->trig = trig;
368
369	if (oldtrig) {
370		if (indio_dev->modes & INDIO_EVENT_TRIGGERED)
371			iio_trigger_detach_poll_func(oldtrig,
372						     indio_dev->pollfunc_event);
373		iio_trigger_put(oldtrig);
374	}
375	if (indio_dev->trig) {
376		iio_trigger_get(indio_dev->trig);
377		if (indio_dev->modes & INDIO_EVENT_TRIGGERED)
378			iio_trigger_attach_poll_func(indio_dev->trig,
379						     indio_dev->pollfunc_event);
380	}
381
382	return len;
383}
384
385static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
386		   iio_trigger_read_current,
387		   iio_trigger_write_current);
388
389static struct attribute *iio_trigger_consumer_attrs[] = {
390	&dev_attr_current_trigger.attr,
391	NULL,
392};
393
394static const struct attribute_group iio_trigger_consumer_attr_group = {
395	.name = "trigger",
396	.attrs = iio_trigger_consumer_attrs,
397};
398
399static void iio_trig_release(struct device *device)
400{
401	struct iio_trigger *trig = to_iio_trigger(device);
402	int i;
403
404	if (trig->subirq_base) {
405		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
406			irq_modify_status(trig->subirq_base + i,
407					  IRQ_NOAUTOEN,
408					  IRQ_NOREQUEST | IRQ_NOPROBE);
409			irq_set_chip(trig->subirq_base + i,
410				     NULL);
411			irq_set_handler(trig->subirq_base + i,
412					NULL);
413		}
414
415		irq_free_descs(trig->subirq_base,
416			       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
417	}
418	kfree(trig->name);
419	kfree(trig);
420}
421
422static struct device_type iio_trig_type = {
423	.release = iio_trig_release,
424	.groups = iio_trig_dev_groups,
425};
426
427static void iio_trig_subirqmask(struct irq_data *d)
428{
429	struct irq_chip *chip = irq_data_get_irq_chip(d);
430	struct iio_trigger *trig
431		= container_of(chip,
432			       struct iio_trigger, subirq_chip);
433	trig->subirqs[d->irq - trig->subirq_base].enabled = false;
434}
435
436static void iio_trig_subirqunmask(struct irq_data *d)
437{
438	struct irq_chip *chip = irq_data_get_irq_chip(d);
439	struct iio_trigger *trig
440		= container_of(chip,
441			       struct iio_trigger, subirq_chip);
442	trig->subirqs[d->irq - trig->subirq_base].enabled = true;
443}
444
445static struct iio_trigger *viio_trigger_alloc(const char *fmt, va_list vargs)
446{
447	struct iio_trigger *trig;
448	trig = kzalloc(sizeof *trig, GFP_KERNEL);
449	if (trig) {
450		int i;
451		trig->dev.type = &iio_trig_type;
452		trig->dev.bus = &iio_bus_type;
453		device_initialize(&trig->dev);
454
455		mutex_init(&trig->pool_lock);
456		trig->subirq_base
457			= irq_alloc_descs(-1, 0,
458					  CONFIG_IIO_CONSUMERS_PER_TRIGGER,
459					  0);
460		if (trig->subirq_base < 0) {
461			kfree(trig);
462			return NULL;
463		}
464
465		trig->name = kvasprintf(GFP_KERNEL, fmt, vargs);
466		if (trig->name == NULL) {
467			irq_free_descs(trig->subirq_base,
468				       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
469			kfree(trig);
470			return NULL;
471		}
472		trig->subirq_chip.name = trig->name;
473		trig->subirq_chip.irq_mask = &iio_trig_subirqmask;
474		trig->subirq_chip.irq_unmask = &iio_trig_subirqunmask;
475		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
476			irq_set_chip(trig->subirq_base + i,
477				     &trig->subirq_chip);
478			irq_set_handler(trig->subirq_base + i,
479					&handle_simple_irq);
480			irq_modify_status(trig->subirq_base + i,
481					  IRQ_NOREQUEST | IRQ_NOAUTOEN,
482					  IRQ_NOPROBE);
483		}
484		get_device(&trig->dev);
485	}
486
487	return trig;
488}
489
490struct iio_trigger *iio_trigger_alloc(const char *fmt, ...)
491{
492	struct iio_trigger *trig;
493	va_list vargs;
494
495	va_start(vargs, fmt);
496	trig = viio_trigger_alloc(fmt, vargs);
497	va_end(vargs);
498
499	return trig;
500}
501EXPORT_SYMBOL(iio_trigger_alloc);
502
503void iio_trigger_free(struct iio_trigger *trig)
504{
505	if (trig)
506		put_device(&trig->dev);
507}
508EXPORT_SYMBOL(iio_trigger_free);
509
510static void devm_iio_trigger_release(struct device *dev, void *res)
511{
512	iio_trigger_free(*(struct iio_trigger **)res);
513}
514
515static int devm_iio_trigger_match(struct device *dev, void *res, void *data)
516{
517	struct iio_trigger **r = res;
518
519	if (!r || !*r) {
520		WARN_ON(!r || !*r);
521		return 0;
522	}
523
524	return *r == data;
525}
526
527/**
528 * devm_iio_trigger_alloc - Resource-managed iio_trigger_alloc()
529 * @dev:		Device to allocate iio_trigger for
530 * @fmt:		trigger name format. If it includes format
531 *			specifiers, the additional arguments following
532 *			format are formatted and inserted in the resulting
533 *			string replacing their respective specifiers.
534 *
535 * Managed iio_trigger_alloc.  iio_trigger allocated with this function is
536 * automatically freed on driver detach.
537 *
538 * If an iio_trigger allocated with this function needs to be freed separately,
539 * devm_iio_trigger_free() must be used.
540 *
541 * RETURNS:
542 * Pointer to allocated iio_trigger on success, NULL on failure.
543 */
544struct iio_trigger *devm_iio_trigger_alloc(struct device *dev,
545						const char *fmt, ...)
546{
547	struct iio_trigger **ptr, *trig;
548	va_list vargs;
549
550	ptr = devres_alloc(devm_iio_trigger_release, sizeof(*ptr),
551			   GFP_KERNEL);
552	if (!ptr)
553		return NULL;
554
555	/* use raw alloc_dr for kmalloc caller tracing */
556	va_start(vargs, fmt);
557	trig = viio_trigger_alloc(fmt, vargs);
558	va_end(vargs);
559	if (trig) {
560		*ptr = trig;
561		devres_add(dev, ptr);
562	} else {
563		devres_free(ptr);
564	}
565
566	return trig;
567}
568EXPORT_SYMBOL_GPL(devm_iio_trigger_alloc);
569
570/**
571 * devm_iio_trigger_free - Resource-managed iio_trigger_free()
572 * @dev:		Device this iio_dev belongs to
573 * @iio_trig:		the iio_trigger associated with the device
574 *
575 * Free iio_trigger allocated with devm_iio_trigger_alloc().
576 */
577void devm_iio_trigger_free(struct device *dev, struct iio_trigger *iio_trig)
578{
579	int rc;
580
581	rc = devres_release(dev, devm_iio_trigger_release,
582			    devm_iio_trigger_match, iio_trig);
583	WARN_ON(rc);
584}
585EXPORT_SYMBOL_GPL(devm_iio_trigger_free);
586
587void iio_device_register_trigger_consumer(struct iio_dev *indio_dev)
588{
589	indio_dev->groups[indio_dev->groupcounter++] =
590		&iio_trigger_consumer_attr_group;
591}
592
593void iio_device_unregister_trigger_consumer(struct iio_dev *indio_dev)
594{
595	/* Clean up an associated but not attached trigger reference */
596	if (indio_dev->trig)
597		iio_trigger_put(indio_dev->trig);
598}
599
600int iio_triggered_buffer_postenable(struct iio_dev *indio_dev)
601{
602	return iio_trigger_attach_poll_func(indio_dev->trig,
603					    indio_dev->pollfunc);
604}
605EXPORT_SYMBOL(iio_triggered_buffer_postenable);
606
607int iio_triggered_buffer_predisable(struct iio_dev *indio_dev)
608{
609	return iio_trigger_detach_poll_func(indio_dev->trig,
610					     indio_dev->pollfunc);
611}
612EXPORT_SYMBOL(iio_triggered_buffer_predisable);
613