Add documentation for:
- iio device buffers describing buffer attributes and how data is structured in
buffers using scan elements.
- adis16475 driver which describes the driver device files and shows how the
user may use the ABI for various scenarios (configuration, measurement, etc.).
This kind of documentation describes how the user can interract with the drivers
device files, showing the driver's particularities and we think all IIO drivers
need such a documentation and will benefit from it.
Having this documentation in the Linux Kernel will make it more accessible to
the user, seeing how it is in the same location as the code.
Analog Devices is prepared to add similar documentation for all new drivers (for
ADI components), and in time to also add documentation for existing drivers,
following the adis16475 documentation template.
Ramona Gradinariu (3):
docs: iio: Refactor index.rst
docs: iio: add documentation for device buffers
docs: iio: add documentation for adis16475 driver
Documentation/iio/adis16475.rst | 406 +++++++++++++++++++++++++++++++
Documentation/iio/iio_devbuf.rst | 152 ++++++++++++
Documentation/iio/index.rst | 9 +-
3 files changed, 566 insertions(+), 1 deletion(-)
create mode 100644 Documentation/iio/adis16475.rst
create mode 100644 Documentation/iio/iio_devbuf.rst
--
2.34.1
Add documentation for IIO device buffers describing buffer
attributes and how data is structured in buffers using
scan elements.
Signed-off-by: Ramona Gradinariu <[email protected]>
---
changes in v5:
- fixed various typos and inconsistencies
- used inline code format style where applicable
- added data padding example
Documentation/iio/iio_devbuf.rst | 152 +++++++++++++++++++++++++++++++
Documentation/iio/index.rst | 1 +
2 files changed, 153 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..9919e4792d0e
--- /dev/null
+++ b/Documentation/iio/iio_devbuf.rst
@@ -0,0 +1,152 @@
+.. 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.
+
+Devices with buffer support feature an additional sub-directory in the
+``/sys/bus/iio/devices/iio:deviceX/`` directory hierarchy, called bufferY, where
+Y defaults to 0, for devices with a single buffer.
+
+2. Buffer attributes
+====================
+
+An IIO buffer has an associated attributes directory under
+``/sys/bus/iio/iio:deviceX/bufferY/``. The attributes are described below.
+
+``length``
+----------
+
+Read / Write attribute which states the total number of data samples (capacity)
+that can be stored by the buffer.
+
+``enable``
+----------
+
+Read / Write attribute which starts / stops the buffer capture. This file should
+be written last, after length and selection of scan elements. Writing a non-zero
+value may result in an error, such as EINVAL, if, for example, an unsupported
+combination of channels is given.
+
+``watermark``
+-------------
+
+Read / Write positive integer attribute specifying the maximum number of scan
+elements to wait for.
+
+Poll will block until the watermark is reached.
+
+Blocking read will wait until the minimum between the requested read amount or
+the low watermark is available.
+
+Non-blocking read will retrieve the available samples from the buffer even if
+there are less samples than the watermark level. This 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.
+
+Data available
+--------------
+
+Read-only attribute indicating the bytes of data available in the buffer. In the
+case of an output buffer, this indicates the amount of empty space available to
+write data to. In the case of an input buffer, this indicates the amount of data
+available for reading.
+
+Scan elements
+-------------
+
+The meta information associated with a channel data placed in a buffer is called
+a scan element. The scan elements attributes are presented below.
+
+**_en**
+
+Read / Write attribute used for enabling a channel. If and only if its value
+is non-zero, then a triggered capture will contain data samples for this
+channel.
+
+**_index**
+
+Read-only unsigned integer attribute specifying the position of the channel in
+the buffer. Note these are not dependent 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.
+
+**_type**
+
+Read-only attribute containing the description of the scan element data storage
+within the buffer and hence the form in which it is read from userspace. Format
+is [be|le]:[s|u]bits/storagebits[Xrepeat][>>shift], where:
+
+- **be** or **le** specifies big or little-endian.
+- **s** or **u** specifies if signed (2's complement) or unsigned.
+- **bits** is the number of valid data bits.
+- **storagebits** is the number of bits (after padding) that it occupies in the
+ buffer.
+- **repeat** specifies the number of bits/storagebits repetitions. When the
+ repeat element is 0 or 1, then the repeat value is omitted.
+- **shift** if specified, is the shift that needs to be applied prior to
+ masking out unused bits.
+
+For example, a driver for a 3-axis accelerometer with 12-bit resolution where
+data is stored in two 8-bit registers is as follows::
+
+ 7 6 5 4 3 2 1 0
+ +---+---+---+---+---+---+---+---+
+ |D3 |D2 |D1 |D0 | X | X | X | X | (LOW byte, address 0x06)
+ +---+---+---+---+---+---+---+---+
+
+ 7 6 5 4 3 2 1 0
+ +---+---+---+---+---+---+---+---+
+ |D11|D10|D9 |D8 |D7 |D6 |D5 |D4 | (HIGH byte, address 0x07)
+ +---+---+---+---+---+---+---+---+
+
+will have the following scan element type for each axis:
+
+.. code-block:: bash
+
+ $ cat /sys/bus/iio/devices/iio:device0/buffer0/in_accel_y_type
+ le:s12/16>>4
+
+A userspace 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.
+
+It is also worth mentioning that the data in the buffer will be naturally
+aligned, so the userspace application has to handle the buffers accordingly.
+
+Take for example, a driver with four channels with the following description:
+- channel0: index: 0, type: be:u16/16>>0
+- channel1: index: 1, type: be:u32/32>>0
+- channel2: index: 2, type: be:u32/32>>0
+- channel3: index: 3, type: be:u64/64>>0
+
+If all channels are enabled, the data will be aligned in the buffer as follows::
+
+ 0-1 2 3 4-7 8-11 12 13 14 15 16-23 -> buffer byte number
+ +-----+---+---+-----+-----+---+---+---+---+-----+
+ |CHN_0|PAD|PAD|CHN_1|CHN_2|PAD|PAD|PAD|PAD|CHN_3| -> buffer content
+ +-----+---+---+-----+-----+---+---+---+---+-----+
+
+If only channel0 and channel3 are enabled, the data will be aligned in the
+buffer as follows::
+
+ 0-1 2 3 4 5 6 7 8-15 -> buffer byte number
+ +-----+---+---+---+---+---+---+-----+
+ |CHN_0|PAD|PAD|PAD|PAD|PAD|PAD|CHN_3| -> buffer content
+ +-----+---+---+---+---+---+---+-----+
+
+Typically the buffered data is found in raw format (unscaled with no offset
+applied), however there are corner cases in which the buffered data may be found
+in a processed form. Please note that these corner cases are not addressed by
+this documentation.
+
+Please see ``Documentation/ABI/testing/sysfs-bus-iio`` for a complete
+description of the attributes.
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
Add documentation for adis16475 driver which describes
the driver device files and shows how the user may use the
ABI for various scenarios (configuration, measurement, etc.).
Signed-off-by: Ramona Gradinariu <[email protected]>
---
changes in v5:
- fixed various typos and inconsistencies
- used inline code format style where applicable
Documentation/iio/adis16475.rst | 406 ++++++++++++++++++++++++++++++++
Documentation/iio/index.rst | 1 +
2 files changed, 407 insertions(+)
create mode 100644 Documentation/iio/adis16475.rst
diff --git a/Documentation/iio/adis16475.rst b/Documentation/iio/adis16475.rst
new file mode 100644
index 000000000000..b4c0917eabc4
--- /dev/null
+++ b/Documentation/iio/adis16475.rst
@@ -0,0 +1,406 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+ADIS16475 driver
+================
+
+This driver supports Analog Device's IMUs on SPI bus.
+
+1. Supported devices
+====================
+
+* `ADIS16465 <https://www.analog.com/ADIS16465>`_
+* `ADIS16467 <https://www.analog.com/ADIS16467>`_
+* `ADIS16470 <https://www.analog.com/ADIS16470>`_
+* `ADIS16475 <https://www.analog.com/ADIS16475>`_
+* `ADIS16477 <https://www.analog.com/ADIS16477>`_
+* `ADIS16500 <https://www.analog.com/ADIS16500>`_
+* `ADIS16505 <https://www.analog.com/ADIS16505>`_
+* `ADIS16507 <https://www.analog.com/ADIS16507>`_
+
+Each supported device is a precision, miniature microelectromechanical system
+(MEMS) inertial measurement unit (IMU) that includes a triaxial gyroscope and a
+triaxial accelerometer. Each inertial sensor in the IMU device combines with
+signal conditioning that optimizes dynamic performance. The factory calibration
+characterizes each sensor for sensitivity, bias, alignment, linear acceleration
+(gyroscope bias), and point of percussion (accelerometer location). As a result,
+each sensor has dynamic compensation formulas that provide accurate sensor
+measurements over a broad set of conditions.
+
+2. Device attributes
+====================
+
+Accelerometer, gyroscope measurements are always provided. Furthermore, the
+driver offers the capability to retrieve the delta angle and the delta velocity
+measurements computed by the device.
+
+The delta angle measurements represent a calculation of angular displacement
+between each sample update, while the delta velocity measurements represent a
+calculation of linear velocity change between each sample update.
+
+Finally, temperature data are provided which show a coarse measurement of
+the temperature inside of the IMU device. This data is most useful for
+monitoring relative changes in the thermal environment.
+
+The signal chain of each inertial sensor (accelerometers and gyroscopes)
+includes the application of unique correction formulas, which are derived from
+extensive characterization of bias, sensitivity, alignment, response to linear
+acceleration (gyroscopes), and point of percussion (accelerometer location)
+over a temperature range of −40°C to +85°C, for each ADIS device. These
+correction formulas are not accessible, but users do have the opportunity to
+adjust the bias for each sensor individually through the calibbias attribute.
+
+Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
+where X is the IIO index of the device. Under these folders reside a set of
+device files, depending on the characteristics and features of the hardware
+device in questions. These files are consistently generalized and documented in
+the IIO ABI documentation.
+
+The following tables show the adis16475 related device files, found in the
+specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
+
++-------------------------------------------+----------------------------------------------------------+
+| 3-Axis Accelerometer related device files | Description |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_scale | Scale for the accelerometer channels. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_calibbias | Calibration offset for the X-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_calibbias_x | x-axis acceleration offset correction |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_raw | Raw X-axis accelerometer channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_calibbias_y | y-axis acceleration offset correction |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_raw | Raw Y-axis accelerometer channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_z_calibbias | Calibration offset for the Z-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_z_raw | Raw Z-axis accelerometer channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_scale | Scale for delta velocity channels. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_x_raw | Raw X-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_y_raw | Raw Y-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+| in_deltavelocity_z_raw | Raw Z-axis delta velocity channel value. |
++-------------------------------------------+----------------------------------------------------------+
+
++---------------------------------------+------------------------------------------------------+
+| 3-Axis Gyroscope related device files | Description |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_scale | Scale for the gyroscope channels. |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_x_calibbias | Calibration offset for the X-axis gyroscope channel. |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_calibbias_x | x-axis gyroscope offset correction |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_x_raw | Raw X-axis gyroscope channel value. |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_calibbias_y | y-axis gyroscope offset correction |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_y_raw | Raw Y-axis gyroscope channel value. |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_z_calibbias | Calibration offset for the Z-axis gyroscope channel. |
++---------------------------------------+------------------------------------------------------+
+| in_anglvel_z_raw | Raw Z-axis gyroscope channel value. |
++---------------------------------------+------------------------------------------------------+
+| in_deltaangl_scale | Scale for delta angle channels. |
++---------------------------------------+------------------------------------------------------+
+| in_deltaangl_x_raw | Raw X-axis delta angle channel value. |
++---------------------------------------+------------------------------------------------------+
+| in_deltaangl_y_raw | Raw Y-axis delta angle channel value. |
++---------------------------------------+------------------------------------------------------+
+| in_deltaangl_z_raw | Raw Z-axis delta angle channel value. |
++---------------------------------------+------------------------------------------------------+
+
++----------------------------------+-------------------------------------------+
+| Temperature sensor related files | Description |
++----------------------------------+-------------------------------------------+
+| in_temp0_raw | Raw temperature channel value. |
++----------------------------------+-------------------------------------------+
+| in_temp0_scale | Scale for the temperature sensor channel. |
++----------------------------------+-------------------------------------------+
+
++-------------------------------+---------------------------------------------------------+
+| Miscellaneous device files | Description |
++-------------------------------+---------------------------------------------------------+
+| name | Name of the IIO device. |
++-------------------------------+---------------------------------------------------------+
+| sampling_frequency | Currently selected sample rate. |
++-------------------------------+---------------------------------------------------------+
+| filter_low_pass_3db_frequency | Bandwidth for the accelerometer and gyroscope channels. |
++-------------------------------+---------------------------------------------------------+
+
+The following table shows the adis16475 related device debug files, found in the
+specific device debug folder path ``/sys/kernel/debug/iio/iio:deviceX``.
+
++----------------------+-------------------------------------------------------------------------+
+| Debugfs device files | Description |
++----------------------+-------------------------------------------------------------------------+
+| serial_number | The serial number of the chip in hexadecimal format. |
++----------------------+-------------------------------------------------------------------------+
+| product_id | Chip specific product id (e.g. 16475, 16500, 16505, etc.). |
++----------------------+-------------------------------------------------------------------------+
+| flash_count | The number of flash writes performed on the device. |
++----------------------+-------------------------------------------------------------------------+
+| firmware_revision | String containing the firmware revision in the following format ##.##. |
++----------------------+-------------------------------------------------------------------------+
+| firmware_date | String containing the firmware date in the following format mm-dd-yyyy. |
++----------------------+-------------------------------------------------------------------------+
+
+Channels processed values
+-------------------------
+
+A channel value can be read from its _raw attribute. The value returned is the
+raw value as reported by the devices. To get the processed value of the channel,
+apply the following formula:
+
+.. code-block:: bash
+
+ processed value = (_raw + _offset) * _scale
+
+Where _offset and _scale are device attributes. If no _offset attribute is
+present, simply assume its value is 0.
+
+The adis16475 driver offers data for 5 types of channels, the table below shows
+the measurement units for the processed value, which are defined by the IIO
+framework:
+
++-------------------------------------+---------------------------+
+| Channel type | Measurement unit |
++-------------------------------------+---------------------------+
+| Acceleration on X, Y, and Z axis | Meters per Second squared |
++-------------------------------------+---------------------------+
+| Angular velocity on X, Y and Z axis | Radians per second |
++-------------------------------------+---------------------------+
+| Delta velocity on X. Y, and Z axis | Meters per Second |
++-------------------------------------+---------------------------+
+| Delta angle on X, Y, and Z axis | Radians |
++-------------------------------------+---------------------------+
+| Temperature | Millidegrees Celsius |
++-------------------------------------+---------------------------+
+
+Usage examples
+--------------
+
+Show device name:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat name
+ adis16505-2
+
+Show accelerometer channels value:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
+ -275924
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
+ -30142222
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
+ 261265769
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
+ 0.000000037
+
+- X-axis acceleration = in_accel_x_raw * in_accel_scale = −0.010209188 m/s^2
+- Y-axis acceleration = in_accel_y_raw * in_accel_scale = −1.115262214 m/s^2
+- Z-axis acceleration = in_accel_z_raw * in_accel_scale = 9.666833453 m/s^2
+
+Show gyroscope channels value:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_x_raw
+ -3324626
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_raw
+ 1336980
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_z_raw
+ -602983
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_scale
+ 0.000000006
+
+- X-axis angular velocity = in_anglvel_x_raw * in_anglvel_scale = −0.019947756 rad/s
+- Y-axis angular velocity = in_anglvel_y_raw * in_anglvel_scale = 0.00802188 rad/s
+- Z-axis angular velocity = in_anglvel_z_raw * in_anglvel_scale = −0.003617898 rad/s
+
+Set calibration offset for accelerometer channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
+ 0
+
+ root:/sys/bus/iio/devices/iio:device0> echo 5000 > in_accel_x_calibbias
+ root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
+ 5000
+
+Set calibration offset for gyroscope channels:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
+ 0
+
+ root:/sys/bus/iio/devices/iio:device0> echo -5000 > in_anglvel_y_calibbias
+ root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
+ -5000
+
+Set sampling frequency:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
+ 2000.000000
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1000 > sampling_frequency
+ 1000.000000
+
+Set bandwidth for accelerometer and gyroscope:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
+ 720
+
+ root:/sys/bus/iio/devices/iio:device0> echo 360 > filter_low_pass_3db_frequency
+ root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
+ 360
+
+Show serial number:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat serial_number
+ 0x04f9
+
+Show product id:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat product_id
+ 16505
+
+Show flash count:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat flash_count
+ 150
+
+Show firmware revision:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat firmware_revision
+ 1.6
+
+Show firmware date:
+
+.. code-block:: bash
+
+ root:/sys/kernel/debug/iio/iio:device0> cat firmware_date
+ 06-27-2019
+
+3. Device buffers
+=================
+
+This driver supports IIO buffers.
+
+All devices support retrieving the raw acceleration, gyroscope and temperature
+measurements using buffers.
+
+The following device families also support retrieving the delta velocity, delta
+angle and temperature measurements using buffers:
+ - ADIS16477
+ - ADIS16500
+ - ADIS16505
+ - ADIS16507
+
+However, when retrieving acceleration or gyroscope data using buffers, delta
+readings will not be available and vice versa.
+
+Usage examples
+--------------
+
+Set device trigger in current_trigger, if not already set:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
+
+ root:/sys/bus/iio/devices/iio:device0> echo adis16505-2-dev0 > trigger/current_trigger
+ root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
+ adis16505-2-dev0
+
+Select channels for buffer read:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_x_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_y_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_z_en
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp0_en
+
+Set the number of samples to be stored in the buffer:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 10 > buffer/length
+
+Enable buffer readings:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
+
+Obtain buffered data:
+
+.. code-block:: bash
+
+ root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
+ ...
+ 00001680 01 1f 00 00 ff ff fe ef 00 00 47 bf 00 03 35 55 |..........G...5U|
+ 00001690 01 1f 00 00 ff ff ff d9 00 00 46 f1 00 03 35 35 |..........F...55|
+ 000016a0 01 1f 00 00 ff ff fe fc 00 00 46 cb 00 03 35 7b |..........F...5{|
+ 000016b0 01 1f 00 00 ff ff fe 41 00 00 47 0d 00 03 35 8b |.......A..G...5.|
+ 000016c0 01 1f 00 00 ff ff fe 37 00 00 46 b4 00 03 35 90 |.......7..F...5.|
+ 000016d0 01 1d 00 00 ff ff fe 5a 00 00 45 d7 00 03 36 08 |.......Z..E...6.|
+ 000016e0 01 1b 00 00 ff ff fe fb 00 00 45 e7 00 03 36 60 |..........E...6`|
+ 000016f0 01 1a 00 00 ff ff ff 17 00 00 46 bc 00 03 36 de |..........F...6.|
+ 00001700 01 1a 00 00 ff ff fe 59 00 00 46 d7 00 03 37 b8 |.......Y..F...7.|
+ 00001710 01 1a 00 00 ff ff fe ae 00 00 46 95 00 03 37 ba |..........F...7.|
+ 00001720 01 1a 00 00 ff ff fe c5 00 00 46 63 00 03 37 9f |..........Fc..7.|
+ 00001730 01 1a 00 00 ff ff fe 55 00 00 46 89 00 03 37 c1 |.......U..F...7.|
+ 00001740 01 1a 00 00 ff ff fe 31 00 00 46 aa 00 03 37 f7 |.......1..F...7.|
+ ...
+
+See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
+data is structured.
+
+4. IIO Interfacing Tools
+========================
+
+Linux Kernel Tools
+------------------
+
+Linux Kernel provides some userspace tools that can be used to retrieve data
+from IIO sysfs:
+
+* lsiio: example application that provides a list of IIO devices and triggers
+* iio_event_monitor: example application that reads events from an IIO device
+ and prints them
+* iio_generic_buffer: example application that reads data from buffer
+* iio_utils: set of APIs, typically used to access sysfs files.
+
+LibIIO
+------
+
+LibIIO is a C/C++ library that provides generic access to IIO devices. The
+library abstracts the low-level details of the hardware, and provides a simple
+yet complete programming interface that can be used for advanced projects.
+
+For more information about LibIIO, please see:
+https://github.com/analogdevicesinc/libiio
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 206a0aff5ca1..30b09eefe75e 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -16,5 +16,6 @@ Industrial I/O Kernel Drivers
.. toctree::
:maxdepth: 1
+ adis16475
bno055
ep93xx_adc
--
2.34.1
Refactor index.rst such that it contains a section for generic
documentation and a section for Kernel Drivers documentation.
Signed-off-by: Ramona Gradinariu <[email protected]>
---
changes in v5:
- no changes
Documentation/iio/index.rst | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 1b7292c58cd0..db341b45397f 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -9,6 +9,11 @@ Industrial I/O
iio_configfs
- ep93xx_adc
+Industrial I/O Kernel Drivers
+=============================
+
+.. toctree::
+ :maxdepth: 1
bno055
+ ep93xx_adc
--
2.34.1
On Wed, 21 Feb 2024 10:58:48 +0200
Ramona Gradinariu <[email protected]> wrote:
> Add documentation for adis16475 driver which describes
> the driver device files and shows how the user may use the
> ABI for various scenarios (configuration, measurement, etc.).
>
> Signed-off-by: Ramona Gradinariu <[email protected]>
Thanks for your work on this. Always good to see some attention paid to docs!
Applied to the togreg branch of iio.git and pushed out initially as
testing. I've no idea if 0-day does docs builds but maybe we will
find out if it finds any issues!
Thanks
Jonathan
> ---
> changes in v5:
> - fixed various typos and inconsistencies
> - used inline code format style where applicable
> Documentation/iio/adis16475.rst | 406 ++++++++++++++++++++++++++++++++
> Documentation/iio/index.rst | 1 +
> 2 files changed, 407 insertions(+)
> create mode 100644 Documentation/iio/adis16475.rst
>
> diff --git a/Documentation/iio/adis16475.rst b/Documentation/iio/adis16475.rst
> new file mode 100644
> index 000000000000..b4c0917eabc4
> --- /dev/null
> +++ b/Documentation/iio/adis16475.rst
> @@ -0,0 +1,406 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +================
> +ADIS16475 driver
> +================
> +
> +This driver supports Analog Device's IMUs on SPI bus.
> +
> +1. Supported devices
> +====================
> +
> +* `ADIS16465 <https://www.analog.com/ADIS16465>`_
> +* `ADIS16467 <https://www.analog.com/ADIS16467>`_
> +* `ADIS16470 <https://www.analog.com/ADIS16470>`_
> +* `ADIS16475 <https://www.analog.com/ADIS16475>`_
> +* `ADIS16477 <https://www.analog.com/ADIS16477>`_
> +* `ADIS16500 <https://www.analog.com/ADIS16500>`_
> +* `ADIS16505 <https://www.analog.com/ADIS16505>`_
> +* `ADIS16507 <https://www.analog.com/ADIS16507>`_
> +
> +Each supported device is a precision, miniature microelectromechanical system
> +(MEMS) inertial measurement unit (IMU) that includes a triaxial gyroscope and a
> +triaxial accelerometer. Each inertial sensor in the IMU device combines with
> +signal conditioning that optimizes dynamic performance. The factory calibration
> +characterizes each sensor for sensitivity, bias, alignment, linear acceleration
> +(gyroscope bias), and point of percussion (accelerometer location). As a result,
> +each sensor has dynamic compensation formulas that provide accurate sensor
> +measurements over a broad set of conditions.
> +
> +2. Device attributes
> +====================
> +
> +Accelerometer, gyroscope measurements are always provided. Furthermore, the
> +driver offers the capability to retrieve the delta angle and the delta velocity
> +measurements computed by the device.
> +
> +The delta angle measurements represent a calculation of angular displacement
> +between each sample update, while the delta velocity measurements represent a
> +calculation of linear velocity change between each sample update.
> +
> +Finally, temperature data are provided which show a coarse measurement of
> +the temperature inside of the IMU device. This data is most useful for
> +monitoring relative changes in the thermal environment.
> +
> +The signal chain of each inertial sensor (accelerometers and gyroscopes)
> +includes the application of unique correction formulas, which are derived from
> +extensive characterization of bias, sensitivity, alignment, response to linear
> +acceleration (gyroscopes), and point of percussion (accelerometer location)
> +over a temperature range of −40°C to +85°C, for each ADIS device. These
> +correction formulas are not accessible, but users do have the opportunity to
> +adjust the bias for each sensor individually through the calibbias attribute.
> +
> +Each IIO device, has a device folder under ``/sys/bus/iio/devices/iio:deviceX``,
> +where X is the IIO index of the device. Under these folders reside a set of
> +device files, depending on the characteristics and features of the hardware
> +device in questions. These files are consistently generalized and documented in
> +the IIO ABI documentation.
> +
> +The following tables show the adis16475 related device files, found in the
> +specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
> +
> ++-------------------------------------------+----------------------------------------------------------+
> +| 3-Axis Accelerometer related device files | Description |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_scale | Scale for the accelerometer channels. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_x_calibbias | Calibration offset for the X-axis accelerometer channel. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_calibbias_x | x-axis acceleration offset correction |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_x_raw | Raw X-axis accelerometer channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_calibbias_y | y-axis acceleration offset correction |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_y_raw | Raw Y-axis accelerometer channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_z_calibbias | Calibration offset for the Z-axis accelerometer channel. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_accel_z_raw | Raw Z-axis accelerometer channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_deltavelocity_scale | Scale for delta velocity channels. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_deltavelocity_x_raw | Raw X-axis delta velocity channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_deltavelocity_y_raw | Raw Y-axis delta velocity channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +| in_deltavelocity_z_raw | Raw Z-axis delta velocity channel value. |
> ++-------------------------------------------+----------------------------------------------------------+
> +
> ++---------------------------------------+------------------------------------------------------+
> +| 3-Axis Gyroscope related device files | Description |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_scale | Scale for the gyroscope channels. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_x_calibbias | Calibration offset for the X-axis gyroscope channel. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_calibbias_x | x-axis gyroscope offset correction |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_x_raw | Raw X-axis gyroscope channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_calibbias_y | y-axis gyroscope offset correction |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_y_raw | Raw Y-axis gyroscope channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_z_calibbias | Calibration offset for the Z-axis gyroscope channel. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_anglvel_z_raw | Raw Z-axis gyroscope channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_deltaangl_scale | Scale for delta angle channels |
> ++---------------------------------------+------------------------------------------------------+
> +| in_deltaangl_x_raw | Raw X-axis delta angle channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_deltaangl_y_raw | Raw Y-axis delta angle channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +| in_deltaangl_z_raw | Raw Z-axis delta angle channel value. |
> ++---------------------------------------+------------------------------------------------------+
> +
> ++----------------------------------+-------------------------------------------+
> +| Temperature sensor related files | Description |
> ++----------------------------------+-------------------------------------------+
> +| in_temp0_raw | Raw temperature channel value. |
> ++----------------------------------+-------------------------------------------+
> +| in_temp0_scale | Scale for the temperature sensor channel. |
> ++----------------------------------+-------------------------------------------+
> +
> ++-------------------------------+---------------------------------------------------------+
> +| Miscellaneous device files | Description |
> ++-------------------------------+---------------------------------------------------------+
> +| name | Name of the IIO device. |
> ++-------------------------------+---------------------------------------------------------+
> +| sampling_frequency | Currently selected sample rate. |
> ++-------------------------------+---------------------------------------------------------+
> +| filter_low_pass_3db_frequency | Bandwidth for the accelerometer and gyroscope channels. |
> ++-------------------------------+---------------------------------------------------------+
> +
> +The following table shows the adis16475 related device debug files, found in the
> +specific device debug folder path ``/sys/kernel/debug/iio/iio:deviceX``.
> +
> ++----------------------+-------------------------------------------------------------------------+
> +| Debugfs device files | Description |
> ++----------------------+-------------------------------------------------------------------------+
> +| serial_number | The serial number of the chip in hexadecimal format. |
> ++----------------------+-------------------------------------------------------------------------+
> +| product_id | Chip specific product id (e.g. 16475, 16500, 16505, etc.). |
> ++----------------------+-------------------------------------------------------------------------+
> +| flash_count | The number of flash writes performed on the device. |
> ++----------------------+-------------------------------------------------------------------------+
> +| firmware_revision | String containing the firmware revision in the following format ##.##. |
> ++----------------------+-------------------------------------------------------------------------+
> +| firmware_date | String containing the firmware date in the following format mm-dd-yyyy. |
> ++----------------------+-------------------------------------------------------------------------+
> +
> +Channels processed values
> +-------------------------
> +
> +A channel value can be read from its _raw attribute. The value returned is the
> +raw value as reported by the devices. To get the processed value of the channel,
> +apply the following formula:
> +
> +.. code-block:: bash
> +
> + processed value = (_raw + _offset) * _scale
> +
> +Where _offset and _scale are device attributes. If no _offset attribute is
> +present, simply assume its value is 0.
> +
> +The adis16475 driver offers data for 5 types of channels, the table below shows
> +the measurement units for the processed value, which are defined by the IIO
> +framework:
> +
> ++-------------------------------------+---------------------------+
> +| Channel type | Measurement unit |
> ++-------------------------------------+---------------------------+
> +| Acceleration on X, Y, and Z axis | Meters per Second squared |
> ++-------------------------------------+---------------------------+
> +| Angular velocity on X, Y and Z axis | Radians per second |
> ++-------------------------------------+---------------------------+
> +| Delta velocity on X. Y, and Z axis | Meters per Second |
> ++-------------------------------------+---------------------------+
> +| Delta angle on X, Y, and Z axis | Radians |
> ++-------------------------------------+---------------------------+
> +| Temperature | Millidegrees Celsius |
> ++-------------------------------------+---------------------------+
> +
> +Usage examples
> +--------------
> +
> +Show device name:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat name
> + adis16505-2
> +
> +Show accelerometer channels value:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
> + -275924
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
> + -30142222
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
> + 261265769
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
> + 0.000000037
> +
> +- X-axis acceleration = in_accel_x_raw * in_accel_scale = −0010209188 m/s^2
> +- Y-axis acceleration = in_accel_y_raw * in_accel_scale = −1115262214 m/s^2
> +- Z-axis acceleration = in_accel_z_raw * in_accel_scale = 9.666833453 m/s^2
> +
> +Show gyroscope channels value:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_x_raw
> + -3324626
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_raw
> + 1336980
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_z_raw
> + -602983
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_scale
> + 0.000000006
> +
> +- X-axis angular velocity = in_anglvel_x_raw * in_anglvel_scale = −0.019947756 rad/s
> +- Y-axis angular velocity = in_anglvel_y_raw * in_anglvel_scale = 0.00802188 rad/s
> +- Z-axis angular velocity = in_anglvel_z_raw * in_anglvel_scale = −0.003617898 rad/s
> +
> +Set calibration offset for accelerometer channels:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
> + 0
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 5000 > in_accel_x_calibbias
> + root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_calibbias
> + 5000
> +
> +Set calibration offset for gyroscope channels:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
> + 0
> +
> + root:/sys/bus/iio/devices/iio:device0> echo -5000 > in_anglvel_y_calibbias
> + root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_calibbias
> + -5000
> +
> +Set sampling frequency:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat sampling_frequency
> + 2000.000000
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 1000 > sampling_frequency
> + 1000.000000
> +
> +Set bandwidth for accelerometer and gyroscope:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
> + 720
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 360 > filter_low_pass_3db_frequency
> + root:/sys/bus/iio/devices/iio:device0> cat filter_low_pass_3db_frequency
> + 360
> +
> +Show serial number:
> +
> +.. code-block:: bash
> +
> + root:/sys/kernel/debug/iio/iio:device0> cat serial_number
> + 0x04f9
> +
> +Show product id:
> +
> +.. code-block:: bash
> +
> + root:/sys/kernel/debug/iio/iio:device0> cat product_id
> + 16505
> +
> +Show flash count:
> +
> +.. code-block:: bash
> +
> + root:/sys/kernel/debug/iio/iio:device0> cat flash_count
> + 150
> +
> +Show firmware revision:
> +
> +.. code-block:: bash
> +
> + root:/sys/kernel/debug/iio/iio:device0> cat firmware_revision
> + 1.6
> +
> +Show firmware date:
> +
> +.. code-block:: bash
> +
> + root:/sys/kernel/debug/iio/iio:device0> cat firmware_date
> + 06-27-2019
> +
> +3. Device buffers
> +=================
> +
> +This driver supports IIO buffers.
> +
> +All devices support retrieving the raw acceleration, gyroscope and temperature
> +measurements using buffers.
> +
> +The following device families also support retrieving the delta velocity, delta
> +angle and temperature measurements using buffers:
> + - ADIS16477
> + - ADIS16500
> + - ADIS16505
> + - ADIS16507
> +
> +However, when retrieving acceleration or gyroscope data using buffers, delta
> +readings will not be available and vice versa.
> +
> +Usage examples
> +--------------
> +
> +Set device trigger in current_trigger, if not already set:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
> +
> + root:/sys/bus/iio/devices/iio:device0> echo adis16505-2-dev0 > trigger/current_trigger
> + root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
> + adis16505-2-dev0
> +
> +Select channels for buffer read:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_x_en
> + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_y_en
> + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_deltavelocity_z_en
> + root:/sys/bus/iio/devices/iio:device0> echo 1 > scan_elements/in_temp0_en
> +
> +Set the number of samples to be stored in the buffer:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 10 > buffer/length
> +
> +Enable buffer readings:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> echo 1 > buffer/enable
> +
> +Obtain buffered data:
> +
> +.. code-block:: bash
> +
> + root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
> + ...
> + 00001680 01 1f 00 00 ff ff fe ef 00 00 47 bf 00 03 35 55 |.........G...5U|
> + 00001690 01 1f 00 00 ff ff ff d9 00 00 46 f1 00 03 35 35 |.........F...55|
> + 000016a0 01 1f 00 00 ff ff fe fc 00 00 46 cb 00 03 35 7b |.........F...5{|
> + 000016b0 01 1f 00 00 ff ff fe 41 00 00 47 0d 00 03 35 8b |......A..G...5.|
> + 000016c0 01 1f 00 00 ff ff fe 37 00 00 46 b4 00 03 35 90 |......7..F...5.|
> + 000016d0 01 1d 00 00 ff ff fe 5a 00 00 45 d7 00 03 36 08 |......Z..E...6.|
> + 000016e0 01 1b 00 00 ff ff fe fb 00 00 45 e7 00 03 36 60 |.........E...6`|
> + 000016f0 01 1a 00 00 ff ff ff 17 00 00 46 bc 00 03 36 de |.........F...6.|
> + 00001700 01 1a 00 00 ff ff fe 59 00 00 46 d7 00 03 37 b8 |......Y..F...7.|
> + 00001710 01 1a 00 00 ff ff fe ae 00 00 46 95 00 03 37 ba |.........F...7.|
> + 00001720 01 1a 00 00 ff ff fe c5 00 00 46 63 00 03 37 9f |.........Fc..7.|
> + 00001730 01 1a 00 00 ff ff fe 55 00 00 46 89 00 03 37 c1 |......U..F...7.|
> + 00001740 01 1a 00 00 ff ff fe 31 00 00 46 aa 00 03 37 f7 |......1..F...7.|
> + ...
> +
> +See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
> +data is structured.
> +
> +4. IIO Interfacing Tools
> +========================
> +
> +Linux Kernel Tools
> +------------------
> +
> +Linux Kernel provides some userspace tools that can be used to retrieve data
> +from IIO sysfs:
> +
> +* lsiio: example application that provides a list of IIO devices and triggers
> +* iio_event_monitor: example application that reads events from an IIO device
> + and prints them
> +* iio_generic_buffer: example application that reads data from buffer
> +* iio_utils: set of APIs, typically used to access sysfs files.
> +
> +LibIIO
> +------
> +
> +LibIIO is a C/C++ library that provides generic access to IIO devices. The
> +library abstracts the low-level details of the hardware, and provides a simple
> +yet complete programming interface that can be used for advanced projects.
> +
> +For more information about LibIIO, please see:
> +https://github.com/analogdevicesinc/libiio
> diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
> index 206a0aff5ca1..30b09eefe75e 100644
> --- a/Documentation/iio/index.rst
> +++ b/Documentation/iio/index.rst
> @@ -16,5 +16,6 @@ Industrial I/O Kernel Drivers
> .. toctree::
> :maxdepth: 1
>
> + adis16475
> bno055
> ep93xx_adc
> --
> 2.34.1
>