On Thu, 8 Feb 2024 12:01:25 +0200 Ramona Gradinariu <ramona.gradinariu@xxxxxxxxxx> wrote: > Add documentation for IIO device buffers describing buffer > attributes and how data is structured in buffers using > scan elements. > > Signed-off-by: Ramona Gradinariu <ramona.gradinariu@xxxxxxxxxx> > --- > changes in v3: > - new patch > Documentation/iio/iio_devbuf.rst | 121 +++++++++++++++++++++++++++++++ > Documentation/iio/index.rst | 1 + > 2 files changed, 122 insertions(+) > create mode 100644 Documentation/iio/iio_devbuf.rst > > diff --git a/Documentation/iio/iio_devbuf.rst b/Documentation/iio/iio_devbuf.rst > new file mode 100644 > index 000000000000..0563b65316cb > --- /dev/null > +++ b/Documentation/iio/iio_devbuf.rst > @@ -0,0 +1,121 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +============================= > +Industrial IIO device buffers > +============================= > + > +1. Overview > +=========== > + > +The Industrial I/O core offers a way for continuous data capture based on a > +trigger source. Multiple data channels can be read at once from > +/dev/iio:deviceX character device node, thus reducing the CPU load. > + > +2. Buffer attributes > +==================== > + > +An IIO buffer has an associated attributes directory under > +/sys/bus/iio/iio:deviceX/buffer/. Here are some of the existing attributes: Given this is new documentation, can we make it compliant from the start with multiple buffer support? bufferY > +3. Scan elements > +================ > + > +The meta information associated with a channel reading placed in a buffer is > +called a scan element. The important bits configuring scan elements are exposed > +to userspace applications via the /sys/bus/iio/iio:deviceX/scan_elements/ Reference the bufferY directory not scan_elements for this as well. ... > + > +A user space application will interpret data samples read from the buffer as two > +byte little endian signed data, that needs a 4 bits right shift before masking > +out the 12 valid bits of data. I can't remember how you do it, but if possible can we have a cross reference to the autogenerated ABI docs. I want those to remain the 'official' definition of ABI with this (excellent btw!) document being the user friendly cut down version. Thanks! Jonathan > diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst > index db341b45397f..206a0aff5ca1 100644 > --- a/Documentation/iio/index.rst > +++ b/Documentation/iio/index.rst > @@ -8,6 +8,7 @@ Industrial I/O > :maxdepth: 1 > > iio_configfs > + iio_devbuf > > Industrial I/O Kernel Drivers > ============================= > -- > 2.34.1 >
