From 63fc53526d3090b27bd06bb43b92e8bc85f46fb1 Mon Sep 17 00:00:00 2001 From: David Lechner Date: Wed, 7 May 2025 15:42:41 -0500 Subject: [PATCH] iio: introduce IIO_DECLARE_BUFFER_WITH_TS macros MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add new macros to help with the common case of declaring a buffer that is safe to use with iio_push_to_buffers_with_ts(). This is not trivial to do correctly because of the alignment requirements of the timestamp. This will make it easier for both authors and reviewers. To avoid double __align() attributes in cases where we also need DMA alignment, add a 2nd variant IIO_DECLARE_DMA_BUFFER_WITH_TS(). Reviewed-by: Nuno Sá Signed-off-by: David Lechner Link: https://patch.msgid.link/20250507-iio-introduce-iio_declare_buffer_with_ts-v6-2-4aee1b9f1b89@baylibre.com Signed-off-by: Jonathan Cameron --- include/linux/iio/iio.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index a574f22398e4..d11668f14a3e 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -7,6 +7,7 @@ #ifndef _INDUSTRIAL_IO_H_ #define _INDUSTRIAL_IO_H_ +#include #include #include #include @@ -784,6 +785,37 @@ static inline void *iio_device_get_drvdata(const struct iio_dev *indio_dev) */ #define IIO_DMA_MINALIGN MAX(ARCH_DMA_MINALIGN, sizeof(s64)) +#define __IIO_DECLARE_BUFFER_WITH_TS(type, name, count) \ + type name[ALIGN((count), sizeof(s64) / sizeof(type)) + sizeof(s64) / sizeof(type)] + +/** + * IIO_DECLARE_BUFFER_WITH_TS() - Declare a buffer with timestamp + * @type: element type of the buffer + * @name: identifier name of the buffer + * @count: number of elements in the buffer + * + * Declares a buffer that is safe to use with iio_push_to_buffer_with_ts(). In + * addition to allocating enough space for @count elements of @type, it also + * allocates space for a s64 timestamp at the end of the buffer and ensures + * proper alignment of the timestamp. + */ +#define IIO_DECLARE_BUFFER_WITH_TS(type, name, count) \ + __IIO_DECLARE_BUFFER_WITH_TS(type, name, count) __aligned(sizeof(s64)) + +/** + * IIO_DECLARE_DMA_BUFFER_WITH_TS() - Declare a DMA-aligned buffer with timestamp + * @type: element type of the buffer + * @name: identifier name of the buffer + * @count: number of elements in the buffer + * + * Same as IIO_DECLARE_BUFFER_WITH_TS(), but is uses __aligned(IIO_DMA_MINALIGN) + * to ensure that the buffer doesn't share cachelines with anything that comes + * before it in a struct. This should not be used for stack-allocated buffers + * as stack memory cannot generally be used for DMA. + */ +#define IIO_DECLARE_DMA_BUFFER_WITH_TS(type, name, count) \ + __IIO_DECLARE_BUFFER_WITH_TS(type, name, count) __aligned(IIO_DMA_MINALIGN) + struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv); /* The information at the returned address is guaranteed to be cacheline aligned */ -- 2.20.1