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authorAlison Schofield <amsfield22@gmail.com>2016-03-09 22:30:12 +0300
committerJonathan Cameron <jic23@kernel.org>2016-03-12 14:17:19 +0300
commit08a33805518e7845486f88287e8aace6f8439391 (patch)
treeb1eccda86f0d406bcd95f24c7c234220ee5d408d /drivers/iio/industrialio-core.c
parente8731180fbf6fd45351b587d67cdc0685ce99a7a (diff)
downloadlinux-08a33805518e7845486f88287e8aace6f8439391.tar.xz
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.c39
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);