[mirror_ubuntu-artful-kernel.git] / drivers / staging / iio / industrialio-trigger.c

/* The industrial I/O core, trigger handling functions
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/slab.h>

#include "iio.h"
#include "trigger.h"
#include "trigger_consumer.h"

/* RFC - Question of approach
 * Make the common case (single sensor single trigger)
 * simple by starting trigger capture from when first sensors
 * is added.
 *
 * Complex simultaneous start requires use of 'hold' functionality
 * of the trigger. (not implemented)
 *
 * Any other suggestions?
 */

static DEFINE_IDR(iio_trigger_idr);
static DEFINE_SPINLOCK(iio_trigger_idr_lock);

/* Single list of all available triggers */
static LIST_HEAD(iio_trigger_list);
static DEFINE_MUTEX(iio_trigger_list_lock);

/**
 * iio_trigger_register_sysfs() - create a device for this trigger
 * @trig_info:	the trigger
 *
 * Also adds any control attribute registered by the trigger driver
 **/
static int iio_trigger_register_sysfs(struct iio_trigger *trig_info)
{
	int ret = 0;

	if (trig_info->control_attrs)
		ret = sysfs_create_group(&trig_info->dev.kobj,
					 trig_info->control_attrs);

	return ret;
}

static void iio_trigger_unregister_sysfs(struct iio_trigger *trig_info)
{
	if (trig_info->control_attrs)
		sysfs_remove_group(&trig_info->dev.kobj,
				   trig_info->control_attrs);
}


/**
 * iio_trigger_register_id() - get a unique id for this trigger
 * @trig_info:	the trigger
 **/
static int iio_trigger_register_id(struct iio_trigger *trig_info)
{
	int ret = 0;

idr_again:
	if (unlikely(idr_pre_get(&iio_trigger_idr, GFP_KERNEL) == 0))
		return -ENOMEM;

	spin_lock(&iio_trigger_idr_lock);
	ret = idr_get_new(&iio_trigger_idr, NULL, &trig_info->id);
	spin_unlock(&iio_trigger_idr_lock);
	if (unlikely(ret == -EAGAIN))
		goto idr_again;
	else if (likely(!ret))
		trig_info->id = trig_info->id & MAX_ID_MASK;

	return ret;
}

/**
 * iio_trigger_unregister_id() - free up unique id for use by another trigger
 * @trig_info: the trigger
 **/
static void iio_trigger_unregister_id(struct iio_trigger *trig_info)
{
	spin_lock(&iio_trigger_idr_lock);
	idr_remove(&iio_trigger_idr, trig_info->id);
	spin_unlock(&iio_trigger_idr_lock);
}

int iio_trigger_register(struct iio_trigger *trig_info)
{
	int ret;

	ret = iio_trigger_register_id(trig_info);
	if (ret)
		goto error_ret;
	/* Set the name used for the sysfs directory etc */
	dev_set_name(&trig_info->dev, "trigger%ld",
		     (unsigned long) trig_info->id);

	ret = device_add(&trig_info->dev);
	if (ret)
		goto error_unregister_id;

	ret = iio_trigger_register_sysfs(trig_info);
	if (ret)
		goto error_device_del;

	/* Add to list of available triggers held by the IIO core */
	mutex_lock(&iio_trigger_list_lock);
	list_add_tail(&trig_info->list, &iio_trigger_list);
	mutex_unlock(&iio_trigger_list_lock);

	return 0;

error_device_del:
	device_del(&trig_info->dev);
error_unregister_id:
	iio_trigger_unregister_id(trig_info);
error_ret:
	return ret;
}
EXPORT_SYMBOL(iio_trigger_register);

void iio_trigger_unregister(struct iio_trigger *trig_info)
{
	struct iio_trigger *cursor;

	mutex_lock(&iio_trigger_list_lock);
	list_for_each_entry(cursor, &iio_trigger_list, list)
		if (cursor == trig_info) {
			list_del(&cursor->list);
			break;
		}
	mutex_unlock(&iio_trigger_list_lock);

	iio_trigger_unregister_sysfs(trig_info);
	iio_trigger_unregister_id(trig_info);
	/* Possible issue in here */
	device_unregister(&trig_info->dev);
}
EXPORT_SYMBOL(iio_trigger_unregister);

static struct iio_trigger *iio_trigger_find_by_name(const char *name,
						    size_t len)
{
	struct iio_trigger *trig = NULL, *iter;

	mutex_lock(&iio_trigger_list_lock);
	list_for_each_entry(iter, &iio_trigger_list, list)
		if (sysfs_streq(iter->name, name)) {
			trig = iter;
			break;
		}
	mutex_unlock(&iio_trigger_list_lock);

	return trig;
}

void iio_trigger_poll(struct iio_trigger *trig, s64 time)
{
	struct iio_poll_func *pf_cursor;

	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
		if (pf_cursor->poll_func_immediate) {
			pf_cursor->poll_func_immediate(pf_cursor->private_data);
			trig->use_count++;
		}
	}
	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
		if (pf_cursor->poll_func_main) {
			pf_cursor->poll_func_main(pf_cursor->private_data,
						  time);
			trig->use_count++;
		}
	}
}
EXPORT_SYMBOL(iio_trigger_poll);

void iio_trigger_notify_done(struct iio_trigger *trig)
{
	trig->use_count--;
	if (trig->use_count == 0 && trig->try_reenable)
		if (trig->try_reenable(trig)) {
			/* Missed and interrupt so launch new poll now */
			iio_trigger_poll(trig, 0);
		}
}
EXPORT_SYMBOL(iio_trigger_notify_done);

/**
 * iio_trigger_read_name() - retrieve useful identifying name
 **/
ssize_t iio_trigger_read_name(struct device *dev,
			      struct device_attribute *attr,
			      char *buf)
{
	struct iio_trigger *trig = dev_get_drvdata(dev);
	return sprintf(buf, "%s\n", trig->name);
}
EXPORT_SYMBOL(iio_trigger_read_name);

/* Trigger Consumer related functions */

/* Complexity in here.  With certain triggers (datardy) an acknowledgement
 * may be needed if the pollfuncs do not include the data read for the
 * triggering device.
 * This is not currently handled.  Alternative of not enabling trigger unless
 * the relevant function is in there may be the best option.
 */
/* Worth protecting against double additions?*/
int iio_trigger_attach_poll_func(struct iio_trigger *trig,
				 struct iio_poll_func *pf)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
	list_add_tail(&pf->list, &trig->pollfunc_list);
	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);

	if (trig->set_trigger_state)
		ret = trig->set_trigger_state(trig, true);
	if (ret) {
		printk(KERN_ERR "set trigger state failed\n");
		list_del(&pf->list);
	}
	return ret;
}
EXPORT_SYMBOL(iio_trigger_attach_poll_func);

int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
				  struct iio_poll_func *pf)
{
	struct iio_poll_func *pf_cursor;
	unsigned long flags;
	int ret = -EINVAL;

	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
		if (pf_cursor == pf) {
			ret = 0;
			break;
		}
	if (!ret) {
		if (list_is_singular(&trig->pollfunc_list)
		    && trig->set_trigger_state) {
			spin_unlock_irqrestore(&trig->pollfunc_list_lock,
					       flags);
			/* May sleep hence cannot hold the spin lock */
			ret = trig->set_trigger_state(trig, false);
			if (ret)
				goto error_ret;
			spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
		}
		/*
		 * Now we can delete safe in the knowledge that, if this is
		 * the last pollfunc then we have disabled the trigger anyway
		 * and so nothing should be able to call the pollfunc.
		 */
		list_del(&pf_cursor->list);
	}
	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);

error_ret:
	return ret;
}
EXPORT_SYMBOL(iio_trigger_dettach_poll_func);

/**
 * iio_trigger_read_currrent() - trigger consumer sysfs query which trigger
 *
 * For trigger consumers the current_trigger interface allows the trigger
 * used by the device to be queried.
 **/
static ssize_t iio_trigger_read_current(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct iio_dev *dev_info = dev_get_drvdata(dev);
	int len = 0;
	if (dev_info->trig)
		len = sprintf(buf,
			      "%s\n",
			      dev_info->trig->name);
	return len;
}

/**
 * iio_trigger_write_current() trigger consumer sysfs set current trigger
 *
 * For trigger consumers the current_trigger interface allows the trigger
 * used for this device to be specified at run time based on the triggers
 * name.
 **/
static ssize_t iio_trigger_write_current(struct device *dev,
					 struct device_attribute *attr,
					 const char *buf,
					 size_t len)
{
	struct iio_dev *dev_info = dev_get_drvdata(dev);
	struct iio_trigger *oldtrig = dev_info->trig;
	mutex_lock(&dev_info->mlock);
	if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
		mutex_unlock(&dev_info->mlock);
		return -EBUSY;
	}
	mutex_unlock(&dev_info->mlock);

	dev_info->trig = iio_trigger_find_by_name(buf, len);
	if (oldtrig && dev_info->trig != oldtrig)
		iio_put_trigger(oldtrig);
	if (dev_info->trig)
		iio_get_trigger(dev_info->trig);

	return len;
}

static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
		   iio_trigger_read_current,
		   iio_trigger_write_current);

static struct attribute *iio_trigger_consumer_attrs[] = {
	&dev_attr_current_trigger.attr,
	NULL,
};

static const struct attribute_group iio_trigger_consumer_attr_group = {
	.name = "trigger",
	.attrs = iio_trigger_consumer_attrs,
};

static void iio_trig_release(struct device *device)
{
	struct iio_trigger *trig = to_iio_trigger(device);
	kfree(trig);
	iio_put();
}

static struct device_type iio_trig_type = {
	.release = iio_trig_release,
};

struct iio_trigger *iio_allocate_trigger(void)
{
	struct iio_trigger *trig;
	trig = kzalloc(sizeof *trig, GFP_KERNEL);
	if (trig) {
		trig->dev.type = &iio_trig_type;
		trig->dev.bus = &iio_bus_type;
		device_initialize(&trig->dev);
		dev_set_drvdata(&trig->dev, (void *)trig);
		spin_lock_init(&trig->pollfunc_list_lock);
		INIT_LIST_HEAD(&trig->list);
		INIT_LIST_HEAD(&trig->pollfunc_list);
		iio_get();
	}
	return trig;
}
EXPORT_SYMBOL(iio_allocate_trigger);

void iio_free_trigger(struct iio_trigger *trig)
{
	if (trig)
		put_device(&trig->dev);
}
EXPORT_SYMBOL(iio_free_trigger);

int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
{
	int ret;
	ret = sysfs_create_group(&dev_info->dev.kobj,
				 &iio_trigger_consumer_attr_group);
	return ret;
}
EXPORT_SYMBOL(iio_device_register_trigger_consumer);

int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
{
	sysfs_remove_group(&dev_info->dev.kobj,
			   &iio_trigger_consumer_attr_group);
	return 0;
}
EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);

int iio_alloc_pollfunc(struct iio_dev *indio_dev,
		       void (*immediate)(struct iio_dev *indio_dev),
		       void (*main)(struct iio_dev *private_data, s64 time))
{
	indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
	if (indio_dev->pollfunc == NULL)
		return -ENOMEM;
	indio_dev->pollfunc->poll_func_immediate = immediate;
	indio_dev->pollfunc->poll_func_main = main;
	indio_dev->pollfunc->private_data = indio_dev;
	return 0;
}
EXPORT_SYMBOL(iio_alloc_pollfunc);

int iio_triggered_ring_postenable(struct iio_dev *indio_dev)
{
	return indio_dev->trig
		? iio_trigger_attach_poll_func(indio_dev->trig,
					       indio_dev->pollfunc)
		: 0;
}
EXPORT_SYMBOL(iio_triggered_ring_postenable);

int iio_triggered_ring_predisable(struct iio_dev *indio_dev)
{
	return indio_dev->trig
		? iio_trigger_dettach_poll_func(indio_dev->trig,
						indio_dev->pollfunc)
		: 0;
}
EXPORT_SYMBOL(iio_triggered_ring_predisable);
Commit	Line	Data
1637db44 JC	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/module.h>
	12	#include <linux/idr.h>
	13	#include <linux/err.h>
	14	#include <linux/device.h>
	15	#include <linux/interrupt.h>
	16	#include <linux/list.h>
5a0e3ad6	17	#include <linux/slab.h>
1637db44 JC	18
	19	#include "iio.h"
	20	#include "trigger.h"
74112d3f	21	#include "trigger_consumer.h"
1637db44 JC	22
	23	/* RFC - Question of approach
	24	* Make the common case (single sensor single trigger)
	25	* simple by starting trigger capture from when first sensors
	26	* is added.
	27	*
	28	* Complex simultaneous start requires use of 'hold' functionality
	29	* of the trigger. (not implemented)
	30	*
	31	* Any other suggestions?
	32	*/
	33
1637db44 JC	34	static DEFINE_IDR(iio_trigger_idr);
	35	static DEFINE_SPINLOCK(iio_trigger_idr_lock);
	36
	37	/* Single list of all available triggers */
	38	static LIST_HEAD(iio_trigger_list);
	39	static DEFINE_MUTEX(iio_trigger_list_lock);
	40
	41	/**
	42	* iio_trigger_register_sysfs() - create a device for this trigger
	43	* @trig_info: the trigger
	44	*
	45	* Also adds any control attribute registered by the trigger driver
	46	**/
	47	static int iio_trigger_register_sysfs(struct iio_trigger *trig_info)
	48	{
	49	int ret = 0;
	50
	51	if (trig_info->control_attrs)
	52	ret = sysfs_create_group(&trig_info->dev.kobj,
	53	trig_info->control_attrs);
	54
	55	return ret;
	56	}
	57
	58	static void iio_trigger_unregister_sysfs(struct iio_trigger *trig_info)
	59	{
	60	if (trig_info->control_attrs)
	61	sysfs_remove_group(&trig_info->dev.kobj,
	62	trig_info->control_attrs);
	63	}
	64
	65
	66	/**
	67	* iio_trigger_register_id() - get a unique id for this trigger
	68	* @trig_info: the trigger
	69	**/
	70	static int iio_trigger_register_id(struct iio_trigger *trig_info)
	71	{
	72	int ret = 0;
	73
	74	idr_again:
	75	if (unlikely(idr_pre_get(&iio_trigger_idr, GFP_KERNEL) == 0))
	76	return -ENOMEM;
	77
	78	spin_lock(&iio_trigger_idr_lock);
	79	ret = idr_get_new(&iio_trigger_idr, NULL, &trig_info->id);
	80	spin_unlock(&iio_trigger_idr_lock);
	81	if (unlikely(ret == -EAGAIN))
	82	goto idr_again;
	83	else if (likely(!ret))
	84	trig_info->id = trig_info->id & MAX_ID_MASK;
	85
	86	return ret;
	87	}
	88
	89	/**
	90	* iio_trigger_unregister_id() - free up unique id for use by another trigger
	91	* @trig_info: the trigger
	92	**/
	93	static void iio_trigger_unregister_id(struct iio_trigger *trig_info)
	94	{
74112d3f GKH	95	spin_lock(&iio_trigger_idr_lock);
	96	idr_remove(&iio_trigger_idr, trig_info->id);
	97	spin_unlock(&iio_trigger_idr_lock);
1637db44 JC	98	}
	99
	100	int iio_trigger_register(struct iio_trigger *trig_info)
	101	{
	102	int ret;
	103
	104	ret = iio_trigger_register_id(trig_info);
	105	if (ret)
	106	goto error_ret;
	107	/* Set the name used for the sysfs directory etc */
	108	dev_set_name(&trig_info->dev, "trigger%ld",
	109	(unsigned long) trig_info->id);
	110
	111	ret = device_add(&trig_info->dev);
	112	if (ret)
	113	goto error_unregister_id;
	114
	115	ret = iio_trigger_register_sysfs(trig_info);
	116	if (ret)
	117	goto error_device_del;
	118
	119	/* Add to list of available triggers held by the IIO core */
	120	mutex_lock(&iio_trigger_list_lock);
	121	list_add_tail(&trig_info->list, &iio_trigger_list);
	122	mutex_unlock(&iio_trigger_list_lock);
	123
	124	return 0;
	125
	126	error_device_del:
	127	device_del(&trig_info->dev);
	128	error_unregister_id:
	129	iio_trigger_unregister_id(trig_info);
	130	error_ret:
	131	return ret;
	132	}
	133	EXPORT_SYMBOL(iio_trigger_register);
	134
	135	void iio_trigger_unregister(struct iio_trigger *trig_info)
	136	{
	137	struct iio_trigger *cursor;
	138
	139	mutex_lock(&iio_trigger_list_lock);
	140	list_for_each_entry(cursor, &iio_trigger_list, list)
	141	if (cursor == trig_info) {
	142	list_del(&cursor->list);
	143	break;
	144	}
	145	mutex_unlock(&iio_trigger_list_lock);
	146
	147	iio_trigger_unregister_sysfs(trig_info);
	148	iio_trigger_unregister_id(trig_info);
	149	/* Possible issue in here */
	150	device_unregister(&trig_info->dev);
	151	}
	152	EXPORT_SYMBOL(iio_trigger_unregister);
	153
f6517f22 JC	154	static struct iio_trigger iio_trigger_find_by_name(const char name,
f6517f22 JC	155	size_t len)
1637db44	156	{
f6517f22	157	struct iio_trigger trig = NULL, iter;
7c327857	158
1637db44	159	mutex_lock(&iio_trigger_list_lock);
f6517f22 JC	160	list_for_each_entry(iter, &iio_trigger_list, list)
	161	if (sysfs_streq(iter->name, name)) {
	162	trig = iter;
1637db44 JC	163	break;
1637db44 JC	164	}
1637db44 JC	165	mutex_unlock(&iio_trigger_list_lock);
1637db44 JC	166
f6517f22	167	return trig;
5f87404d	168	}
1637db44	169
7b2c33b1	170	void iio_trigger_poll(struct iio_trigger *trig, s64 time)
1637db44 JC	171	{
	172	struct iio_poll_func *pf_cursor;
	173
	174	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
	175	if (pf_cursor->poll_func_immediate) {
	176	pf_cursor->poll_func_immediate(pf_cursor->private_data);
	177	trig->use_count++;
	178	}
	179	}
	180	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
	181	if (pf_cursor->poll_func_main) {
7b2c33b1 JC	182	pf_cursor->poll_func_main(pf_cursor->private_data,
7b2c33b1 JC	183	time);
1637db44 JC	184	trig->use_count++;
	185	}
	186	}
	187	}
	188	EXPORT_SYMBOL(iio_trigger_poll);
	189
	190	void iio_trigger_notify_done(struct iio_trigger *trig)
	191	{
	192	trig->use_count--;
	193	if (trig->use_count == 0 && trig->try_reenable)
	194	if (trig->try_reenable(trig)) {
	195	/* Missed and interrupt so launch new poll now */
7b2c33b1	196	iio_trigger_poll(trig, 0);
1637db44 JC	197	}
	198	}
	199	EXPORT_SYMBOL(iio_trigger_notify_done);
	200
	201	/**
	202	* iio_trigger_read_name() - retrieve useful identifying name
	203	**/
	204	ssize_t iio_trigger_read_name(struct device *dev,
	205	struct device_attribute *attr,
	206	char *buf)
	207	{
	208	struct iio_trigger *trig = dev_get_drvdata(dev);
	209	return sprintf(buf, "%s\n", trig->name);
	210	}
	211	EXPORT_SYMBOL(iio_trigger_read_name);
	212
	213	/* Trigger Consumer related functions */
	214
	215	/* Complexity in here. With certain triggers (datardy) an acknowledgement
	216	* may be needed if the pollfuncs do not include the data read for the
	217	* triggering device.
	218	* This is not currently handled. Alternative of not enabling trigger unless
	219	* the relevant function is in there may be the best option.
	220	*/
	221	/* Worth protecting against double additions?*/
	222	int iio_trigger_attach_poll_func(struct iio_trigger *trig,
	223	struct iio_poll_func *pf)
	224	{
	225	int ret = 0;
	226	unsigned long flags;
	227
	228	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
	229	list_add_tail(&pf->list, &trig->pollfunc_list);
	230	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
	231
	232	if (trig->set_trigger_state)
	233	ret = trig->set_trigger_state(trig, true);
	234	if (ret) {
	235	printk(KERN_ERR "set trigger state failed\n");
	236	list_del(&pf->list);
	237	}
	238	return ret;
	239	}
	240	EXPORT_SYMBOL(iio_trigger_attach_poll_func);
	241
	242	int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
	243	struct iio_poll_func *pf)
	244	{
	245	struct iio_poll_func *pf_cursor;
	246	unsigned long flags;
	247	int ret = -EINVAL;
	248
	249	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
	250	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
	251	if (pf_cursor == pf) {
	252	ret = 0;
	253	break;
	254	}
	255	if (!ret) {
	256	if (list_is_singular(&trig->pollfunc_list)
	257	&& trig->set_trigger_state) {
	258	spin_unlock_irqrestore(&trig->pollfunc_list_lock,
	259	flags);
	260	/* May sleep hence cannot hold the spin lock */
261	ret = trig->set_trigger_state(trig, false);
262	if (ret)
263	goto error_ret;
264	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
265	}
266	/*
267	* Now we can delete safe in the knowledge that, if this is
268	* the last pollfunc then we have disabled the trigger anyway
269	* and so nothing should be able to call the pollfunc.
270	*/
271	list_del(&pf_cursor->list);
272	}
273	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
274
275	error_ret:
276	return ret;
277	}
278	EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
279
280	/**
751a3700	281	* iio_trigger_read_currrent() - trigger consumer sysfs query which trigger
1637db44 JC	282	*
	283	* For trigger consumers the current_trigger interface allows the trigger
	284	* used by the device to be queried.
	285	**/
	286	static ssize_t iio_trigger_read_current(struct device *dev,
	287	struct device_attribute *attr,
	288	char *buf)
	289	{
	290	struct iio_dev *dev_info = dev_get_drvdata(dev);
	291	int len = 0;
	292	if (dev_info->trig)
3c9bbf58 JC	293	len = sprintf(buf,
	294	"%s\n",
	295	dev_info->trig->name);
1637db44 JC	296	return len;
	297	}
	298
	299	/**
	300	* iio_trigger_write_current() trigger consumer sysfs set current trigger
	301	*
	302	* For trigger consumers the current_trigger interface allows the trigger
	303	* used for this device to be specified at run time based on the triggers
	304	* name.
	305	**/
	306	static ssize_t iio_trigger_write_current(struct device *dev,
	307	struct device_attribute *attr,
	308	const char *buf,
	309	size_t len)
	310	{
	311	struct iio_dev *dev_info = dev_get_drvdata(dev);
	312	struct iio_trigger *oldtrig = dev_info->trig;
	313	mutex_lock(&dev_info->mlock);
	314	if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
	315	mutex_unlock(&dev_info->mlock);
	316	return -EBUSY;
	317	}
	318	mutex_unlock(&dev_info->mlock);
	319
1637db44 JC	320	dev_info->trig = iio_trigger_find_by_name(buf, len);
	321	if (oldtrig && dev_info->trig != oldtrig)
	322	iio_put_trigger(oldtrig);
	323	if (dev_info->trig)
	324	iio_get_trigger(dev_info->trig);
	325
	326	return len;
	327	}
	328
74112d3f GKH	329	static DEVICE_ATTR(current_trigger, S_IRUGO \| S_IWUSR,
	330	iio_trigger_read_current,
	331	iio_trigger_write_current);
1637db44 JC	332
	333	static struct attribute *iio_trigger_consumer_attrs[] = {
	334	&dev_attr_current_trigger.attr,
	335	NULL,
	336	};
	337
	338	static const struct attribute_group iio_trigger_consumer_attr_group = {
	339	.name = "trigger",
	340	.attrs = iio_trigger_consumer_attrs,
	341	};
	342
	343	static void iio_trig_release(struct device *device)
	344	{
	345	struct iio_trigger *trig = to_iio_trigger(device);
	346	kfree(trig);
	347	iio_put();
	348	}
	349
	350	static struct device_type iio_trig_type = {
	351	.release = iio_trig_release,
	352	};
	353
	354	struct iio_trigger *iio_allocate_trigger(void)
	355	{
	356	struct iio_trigger *trig;
	357	trig = kzalloc(sizeof *trig, GFP_KERNEL);
	358	if (trig) {
	359	trig->dev.type = &iio_trig_type;
5aaaeba8	360	trig->dev.bus = &iio_bus_type;
1637db44 JC	361	device_initialize(&trig->dev);
	362	dev_set_drvdata(&trig->dev, (void *)trig);
	363	spin_lock_init(&trig->pollfunc_list_lock);
	364	INIT_LIST_HEAD(&trig->list);
	365	INIT_LIST_HEAD(&trig->pollfunc_list);
	366	iio_get();
	367	}
	368	return trig;
	369	}
	370	EXPORT_SYMBOL(iio_allocate_trigger);
	371
	372	void iio_free_trigger(struct iio_trigger *trig)
	373	{
	374	if (trig)
	375	put_device(&trig->dev);
	376	}
	377	EXPORT_SYMBOL(iio_free_trigger);
	378
	379	int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
	380	{
	381	int ret;
	382	ret = sysfs_create_group(&dev_info->dev.kobj,
	383	&iio_trigger_consumer_attr_group);
	384	return ret;
	385	}
	386	EXPORT_SYMBOL(iio_device_register_trigger_consumer);
	387
	388	int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
	389	{
	390	sysfs_remove_group(&dev_info->dev.kobj,
	391	&iio_trigger_consumer_attr_group);
	392	return 0;
	393	}
	394	EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);
	395
15744090 JC	396	int iio_alloc_pollfunc(struct iio_dev *indio_dev,
15744090 JC	397	void (immediate)(struct iio_dev indio_dev),
7b2c33b1	398	void (main)(struct iio_dev private_data, s64 time))
15744090 JC	399	{
	400	indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
	401	if (indio_dev->pollfunc == NULL)
	402	return -ENOMEM;
	403	indio_dev->pollfunc->poll_func_immediate = immediate;
	404	indio_dev->pollfunc->poll_func_main = main;
	405	indio_dev->pollfunc->private_data = indio_dev;
	406	return 0;
	407	}
	408	EXPORT_SYMBOL(iio_alloc_pollfunc);
c3db00cc JC	409
	410	int iio_triggered_ring_postenable(struct iio_dev *indio_dev)
	411	{
	412	return indio_dev->trig
	413	? iio_trigger_attach_poll_func(indio_dev->trig,
	414	indio_dev->pollfunc)
	415	: 0;
	416	}
	417	EXPORT_SYMBOL(iio_triggered_ring_postenable);
	418
	419	int iio_triggered_ring_predisable(struct iio_dev *indio_dev)
	420	{
	421	return indio_dev->trig
	422	? iio_trigger_dettach_poll_func(indio_dev->trig,
	423	indio_dev->pollfunc)
	424	: 0;
	425	}
	426	EXPORT_SYMBOL(iio_triggered_ring_predisable);