Documentation/iio/iio_devbuf.rst

1 .. SPDX-License-Identifier: GPL-2.0
14 Devices with buffer support feature an additional sub-directory in the
25 ----------
31 ----------
34 be written last, after length and selection of scan elements. Writing a non-zero
39 -------------
41 Read / Write positive integer attribute specifying the maximum number of scan
49 Non-blocking read will retrieve the available samples from the buffer even if
55 --------------
57 Read-only attribute indicating the bytes of data available in the buffer. In the
63 -------------
71 is non-zero, then a triggered capture will contain data samples for this
76 Read-only unsigned integer attribute specifying the position of the channel in
84 Read-only attribute containing the description of the scan element data storage
88 - **be** or **le** specifies big or little-endian.
89 - **s** or **u** specifies if signed (2's complement) or unsigned.
90 - **bits** is the number of valid data bits.
91 - **storagebits** is the number of bits (after padding) that it occupies in the
93 - **repeat** specifies the number of bits/storagebits repetitions. When the
95 - **shift** if specified, is the shift that needs to be applied prior to
98 For example, a driver for a 3-axis accelerometer with 12-bit resolution where
99 data is stored in two 8-bit registers is as follows::
102         +---+---+---+---+---+---+---+---+
104         +---+---+---+---+---+---+---+---+
107         +---+---+---+---+---+---+---+---+
109         +---+---+---+---+---+---+---+---+
113 .. code-block:: bash
119 two-byte little-endian signed data, that needs a 4 bits right shift before
126 - channel0: index: 0, type: be:u16/16>>0
127 - channel1: index: 1, type: be:u32/32>>0
128 - channel2: index: 2, type: be:u32/32>>0
129 - channel3: index: 3, type: be:u64/64>>0
133           0-1   2   3   4-7  8-11  12  13  14  15  16-23   -> buffer byte number
134         +-----+---+---+-----+-----+---+---+---+---+-----+
135         |CHN_0|PAD|PAD|CHN_1|CHN_2|PAD|PAD|PAD|PAD|CHN_3|  -> buffer content
136         +-----+---+---+-----+-----+---+---+---+---+-----+
141           0-1   2   3   4   5   6   7  8-15    -> buffer byte number
142         +-----+---+---+---+---+---+---+-----+
143         |CHN_0|PAD|PAD|PAD|PAD|PAD|PAD|CHN_3|  -> buffer content
144         +-----+---+---+---+---+---+---+-----+
146 Typically the buffered data is found in raw format (unscaled with no offset
147 applied), however there are corner cases in which the buffered data may be found
151 Please see ``Documentation/ABI/testing/sysfs-bus-iio`` for a complete