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Commit 08a33805 authored by Alison Schofield's avatar Alison Schofield Committed by Jonathan Cameron
Browse files

iio: core: implement iio_device_{claim|release}_direct_mode() 



It is often the case that the driver wants to be sure a device stays
in direct mode while it is executing a task or series of tasks.  To
accomplish this today, the driver performs this sequence: 1) take the
device state lock, 2) verify it is not in a buffered mode, 3) execute
some tasks, and 4) release that lock.

This patch introduces a pair of helper functions that simplify these
steps and make it more semantically expressive.

iio_device_claim_direct_mode()
        If the device is not in any buffered mode it is guaranteed
        to stay that way until iio_release_direct_mode() is called.

iio_device_release_direct_mode()
        Release the claim. Device is no longer guaranteed to stay
        in direct mode.

Signed-off-by: default avatarAlison Schofield <amsfield22@gmail.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent e8731180

drivers/iio/industrialio-core.c

+39 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/slab.h>

#include <linux/anon_inodes.h>

#include <linux/debugfs.h>

#include <linux/mutex.h>

#include <linux/iio/iio.h>

#include "iio_core.h"

#include "iio_core_trigger.h"
@@ -1375,6 +1376,44 @@ void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev) 
}

EXPORT_SYMBOL_GPL(devm_iio_device_unregister);



/**

 * iio_device_claim_direct_mode - Keep device in direct mode

 * @indio_dev:	the iio_dev associated with the device

 *

 * If the device is in direct mode it is guaranteed to stay

 * that way until iio_device_release_direct_mode() is called.

 *

 * Use with iio_device_release_direct_mode()

 *

 * Returns: 0 on success, -EBUSY on failure

 */

int iio_device_claim_direct_mode(struct iio_dev *indio_dev)

{

	mutex_lock(&indio_dev->mlock);



	if (iio_buffer_enabled(indio_dev)) {

		mutex_unlock(&indio_dev->mlock);

		return -EBUSY;

	}

	return 0;

}

EXPORT_SYMBOL_GPL(iio_device_claim_direct_mode);



/**

 * iio_device_release_direct_mode - releases claim on direct mode

 * @indio_dev:	the iio_dev associated with the device

 *

 * Release the claim. Device is no longer guaranteed to stay

 * in direct mode.

 *

 * Use with iio_device_claim_direct_mode()

 */

void iio_device_release_direct_mode(struct iio_dev *indio_dev)

{

	mutex_unlock(&indio_dev->mlock);

}

EXPORT_SYMBOL_GPL(iio_device_release_direct_mode);



subsys_initcall(iio_init);

module_exit(iio_exit);

include/linux/iio/iio.h

+2 −0
Original line number Diff line number Diff line
@@ -527,6 +527,8 @@ void iio_device_unregister(struct iio_dev *indio_dev); 
int devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev);

void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev);

int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp);

int iio_device_claim_direct_mode(struct iio_dev *indio_dev);

void iio_device_release_direct_mode(struct iio_dev *indio_dev);



extern struct bus_type iio_bus_type;