[PATCH 6.19 191/311] iio: add IIO_DECLARE_QUATERNION() macro

Greg Kroah-Hartman
2026-04-08T18:57:57Z

From: David Lechner <dlechner@baylibre.com>

commit 56bd57e7b161f75535df91b229b0b2c64c6e5581 upstream.

Add a new IIO_DECLARE_QUATERNION() macro that is used to declare the
field in an IIO buffer struct that contains a quaternion vector.

Quaternions are currently the only IIO data type that uses the .repeat
feature of struct iio_scan_type. This has an implicit rule that the
element in the buffer must be aligned to the entire size of the repeated
element. This macro will make that requirement explicit. Since this is
the only user, we just call the macro IIO_DECLARE_QUATERNION() instead
of something more generic.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/iio/iio.h | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -816,6 +816,18 @@ static inline void *iio_device_get_drvda
#define IIO_DECLARE_DMA_BUFFER_WITH_TS(type, name, count) \
__IIO_DECLARE_BUFFER_WITH_TS(type, name, count) __aligned(IIO_DMA_MINALIGN)

+/**
+ * IIO_DECLARE_QUATERNION() - Declare a quaternion element
+ * @type: element type of the individual vectors
+ * @name: identifier name
+ *
+ * Quaternions are a vector composed of 4 elements (W, X, Y, Z). Use this macro
+ * to declare a quaternion element in a struct to ensure proper alignment in
+ * an IIO buffer.
+ */
+#define IIO_DECLARE_QUATERNION(type, name) \
+ type name[4] __aligned(sizeof(type) * 4)
+
struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv);

/* The information at the returned address is guaranteed to be cacheline aligned */