[PATCH v2 10/12] iio: core: Add support for cyclic buffers

Paul Cercueil
2022-02-07T13:16:56Z

Introduce a new flag IIO_BUFFER_DMABUF_CYCLIC in the "flags" field of
the iio_dmabuf uapi structure.

When set, the DMABUF enqueued with the enqueue ioctl will be endlessly
repeated on the TX output, until the buffer is disabled.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
---
drivers/iio/industrialio-buffer.c | 5 +++++
include/uapi/linux/iio/buffer.h | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 72f333a519bc..85331cedaad8 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1535,6 +1535,11 @@ static int iio_buffer_enqueue_dmabuf(struct iio_buffer *buffer,
if (dmabuf.flags & ~IIO_BUFFER_DMABUF_SUPPORTED_FLAGS)
return -EINVAL;

+ /* Cyclic flag is only supported on output buffers */
+ if ((dmabuf.flags & IIO_BUFFER_DMABUF_CYCLIC) &&
+ buffer->direction != IIO_BUFFER_DIRECTION_OUT)
+ return -EINVAL;
+
return buffer->access->enqueue_dmabuf(buffer, &dmabuf);
}

diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h
index e4621b926262..2d541d038c02 100644
--- a/include/uapi/linux/iio/buffer.h
+++ b/include/uapi/linux/iio/buffer.h
@@ -7,7 +7,8 @@

#include <linux/types.h>

-#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000000
+#define IIO_BUFFER_DMABUF_CYCLIC (1 << 0)
+#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000001

/**
* struct iio_dmabuf_alloc_req - Descriptor for allocating IIO DMABUFs
--
2.34.1