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iio: Introduce iio_validate_scan_mask_onehot 

Add a helper function for validating a scan mask for devices where exactly one
channel must be selected during sampling. This is a common case among devices
which have scan mask restrictions so it makes sense to provide this function in
the core.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2012-07-09 10:00:00 +01:00 committed by Jonathan Cameron
parent 939546d1a9
commit 8163663205
2 changed files with 19 additions and 0 deletions
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16
drivers/iio/industrialio-buffer.c
View File

@ -570,6 +570,22 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
}
EXPORT_SYMBOL(iio_sw_buffer_preenable);
/**
* iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
* @indio_dev: the iio device
* @mask: scan mask to be checked
*
* Return true if exactly one bit is set in the scan mask, false otherwise. It
* can be used for devices where only one channel can be active for sampling at
* a time.
*/
bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
const unsigned long *mask)
{
return bitmap_weight(mask, indio_dev->masklength) == 1;
}
EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
const unsigned long *mask)
{

3
include/linux/iio/buffer.h
View File

@ -177,6 +177,9 @@ ssize_t iio_buffer_show_enable(struct device *dev,
int iio_sw_buffer_preenable(struct iio_dev *indio_dev);
bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
const unsigned long *mask);
#else /* CONFIG_IIO_BUFFER */
static inline int iio_buffer_register(struct iio_dev *indio_dev,