1 files changed, 69 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 0b6f0abf3370..6bf79072179f 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1295,3 +1295,72 @@ Description:
                 allows the application to block on poll with a timeout and read
                 the available samples after the timeout expires and thus have a
                 maximum delay guarantee.
+
+What:           /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_enabled
+KernelVersion: 4.2
+Contact:        linux-iio@vger.kernel.org
+Description:
+                A read-only boolean value that indicates if the hardware fifo is
+                currently enabled or disabled. If the device does not have a
+                hardware fifo this entry is not present.
+                The hardware fifo is enabled when the buffer is enabled if the
+                current hardware fifo watermark level is set and other current
+                device settings allows it (e.g. if a trigger is set that samples
+                data differently that the hardware fifo does then hardware fifo
+                will not enabled).
+                If the hardware fifo is enabled and the level of the hardware
+                fifo reaches the hardware fifo watermark level the device will
+                flush its hardware fifo to the device buffer. Doing a non
+                blocking read on the device when no samples are present in the
+                device buffer will also force a flush.
+                When the hardware fifo is enabled there is no need to use a
+                trigger to use buffer mode since the watermark settings
+                guarantees that the hardware fifo is flushed to the device
+                buffer.
+
+What:           /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_watermark
+KernelVersion: 4.2
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Read-only entry that contains a single integer specifying the
+                current watermark level for the hardware fifo. If the device
+                does not have a hardware fifo this entry is not present.
+                The watermark level for the hardware fifo is set by the driver
+                based on the value set by the user in buffer/watermark but
+                taking into account hardware limitations (e.g. most hardware
+                buffers are limited to 32-64 samples, some hardware buffers
+                watermarks are fixed or have minimum levels).  A value of 0
+                means that the hardware watermark is unset.
+
+What:           /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_watermark_min
+KernelVersion: 4.2
+Contact:       linux-iio@vger.kernel.org
+Description:
+                A single positive integer specifying the minimum watermark level
+                for the hardware fifo of this device. If the device does not
+                have a hardware fifo this entry is not present.
+                If the user sets buffer/watermark to a value less than this one,
+                then the hardware watermark will remain unset.
+
+What:          /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_watermark_max
+KernelVersion: 4.2
+Contact:       linux-iio@vger.kernel.org
+Description:
+                A single positive integer specifying the maximum watermark level
+                for the hardware fifo of this device. If the device does not
+                have a hardware fifo this entry is not present.
+                If the user sets buffer/watermark to a value greater than this
+                one, then the hardware watermark will be capped at this value.
+
+What:          /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_watermark_available
+KernelVersion: 4.2
+Contact:       linux-iio@vger.kernel.org
+Description:
+                A list of positive integers specifying the available watermark
+                levels for the hardware fifo. This entry is optional and if it
+                is not present it means that all the values between
+                hwfifo_watermark_min and hwfifo_watermark_max are supported.
+                If the user sets buffer/watermark to a value greater than
+                hwfifo_watermak_min but not equal to any of the values in this
+                list, the driver will chose an appropriate value for the
+                hardware fifo watermark level.