diff options
author | Alison Schofield <amsfield22@gmail.com> | 2016-03-09 20:30:12 +0100 |
---|---|---|
committer | Jonathan Cameron <jic23@kernel.org> | 2016-03-12 12:17:19 +0100 |
commit | 08a33805518e7845486f88287e8aace6f8439391 (patch) | |
tree | b1eccda86f0d406bcd95f24c7c234220ee5d408d /drivers/iio/industrialio-core.c | |
parent | iio: mma8452: add support for FXLS8471Q (diff) | |
download | linux-08a33805518e7845486f88287e8aace6f8439391.tar.xz linux-08a33805518e7845486f88287e8aace6f8439391.zip |
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: Alison Schofield <amsfield22@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio/industrialio-core.c')
-rw-r--r-- | drivers/iio/industrialio-core.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 70cb7eb0a75c..2e768bc99f05 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -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); |