staging: iio: sysfs abi documentation. Add _type and _index attrs

Also remove no unused precision attr.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Manuel Stahl <manuel.stahl@iis.fraunhofer.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/iio/Documentation/sysfs-bus-iio b/drivers/staging/iio/Documentation/sysfs-bus-iio
index c13702037b089e776ac949aff6028e80ec3436b6..62becc0cdb76dcc3502f7016790e802d104af073 100644 (file)
--- a/drivers/staging/iio/Documentation/sysfs-bus-iio
+++ b/drivers/staging/iio/Documentation/sysfs-bus-iio
@@ -266,24 +266,41 @@ Description:
                Directory containing interfaces for elements that will be captured
                for a single triggered sample set in the buffer.
 
-What:          /sys/.../device[n]/buffer/scan_elements/[m]_accel_x0_en
+What:          /sys/.../device[n]/buffer/scan_elements/accel_x0_en
 KernelVersion: 2.6.37
 Contact:       linux-iio@vger.kernel.org
 Description:
-               Scan element control for triggered data capture. m implies the
-               ordering within the buffer. Next the type is specified with
-               modifier and channel number as per the sysfs single channel
-               access above.
+               Scan element control for triggered data capture.
 
-What:          /sys/.../device[n]/buffer/scan_elements/accel[_x0]_precision
+What:          /sys/.../device[n]/buffer/scan_elements/accel[_x0]_type
 KernelVersion: 2.6.37
 Contact:       linux-iio@vger.kernel.org
 Description:
-               Scan element precision within the buffer. Note that the
-               data alignment must restrictions must be read from within
-               buffer to work out full data alignment for data read
-               via buffer_access chrdev. _x0 dropped if shared across all
-               acceleration channels.
+               Description of the scan element data storage within the buffer
+               and hence the form in which it is read from userspace.
+               Form is [s|u]bits/storagebits.  s or u specifies if signed
+               (2's complement) or unsigned. bits is the number of bits of
+               data and storagebits is the space (after padding) that it
+               occupies in the buffer.  Note that some devices will have
+               additional information in the unused bits so to get a clean
+               value, the bits value must be used to mask the buffer output
+               value appropriately.  The storagebits value also specifies the
+               data alignment.  So s48/64 will be a signed 48 bit integer
+               stored in a 64 bit location aligned to a a64 bit boundary.
+               For other storage combinations this attribute will be extended
+               appropriately.
+
+What:          /sys/.../device[n]/buffer/scan_elements/accel[_x0]_index
+KernelVersion: 2.6.37
+Contact:       linux-iio@vger.kernel.org
+Description:
+               A single positive integer specifying the position of this
+               scan element in the buffer. Note these are not dependant on
+               what is enabled and may not be contiguous. Thus for userspace
+               to establish the full layout these must be used in conjunction
+               with all _en attributes to establish which channels are present,
+               and the relevant _type attributes to establish the data storage
+               format.
 
 What:          /sys/.../device[n]/buffer/scan_elements/accel[_x0]_shift
 KernelVersion: 2.6.37
@@ -291,4 +308,3 @@ Contact:    linux-iio@vger.kernel.org
 Description:
                A bit shift (to right) that must be applied prior to
                extracting the bits specified by accel[_x0]_precision.
-