docs: iio: add documentation for adis16480 driver

Add documentation for adis16480 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 <ramona.gradinariu@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240528142409.239187-7-ramona.gradinariu@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

2 files changed, 444 insertions, 0 deletions

diff --git a/Documentation/iio/adis16480.rst b/Documentation/iio/adis16480.rst
new file mode 100644
index 000000000000..bc78fa04d958
--- /dev/null
+++ b/Documentation/iio/adis16480.rst
@@ -0,0 +1,443 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+ADIS16480 driver
+================
+
+This driver supports Analog Device's IMUs on SPI bus.
+
+1. Supported devices
+====================
+
+* `ADIS16375 <https://www.analog.com/ADIS16375>`_
+* `ADIS16480 <https://www.analog.com/ADIS16480>`_
+* `ADIS16485 <https://www.analog.com/ADIS16485>`_
+* `ADIS16488 <https://www.analog.com/ADIS16488>`_
+* `ADIS16490 <https://www.analog.com/ADIS16490>`_
+* `ADIS16495 <https://www.analog.com/ADIS16495>`_
+* `ADIS16497 <https://www.analog.com/ADIS16497>`_
+* `ADIS16545 <https://www.analog.com/ADIS16545>`_
+* `ADIS16547 <https://www.analog.com/ADIS16547>`_
+
+Each supported device is a complete inertial system that includes a triaxial
+gyroscope and a triaxial accelerometer. Each inertial sensor in device combines
+with signal conditioning that optimizes dynamic performance. The factory
+calibration characterizes each sensor for sensitivity, bias, and alignment. As
+a result, each sensor has its own dynamic compensation formulas that provide
+accurate sensor measurements.
+
+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.
+
+ADIS16480 and ADIS16488 also provide access to barometric pressure data and
+triaxial magnetometer measurements.
+
+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 adis16480 related device files, found in the
+specific device folder path ``/sys/bus/iio/devices/iio:deviceX``.
+
+**Available only for ADIS16480 and ADIS16488:**
+
++------------------------------------------+---------------------------------------------------------+
+| 3-Axis Magnetometer related device files | Description                                             |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_scale                            | Scale for the magnetometer channels.                    |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_x_calibbias                      | Calibration offset for the X-axis magnetometer channel. |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_x_filter_low_pass_3db_frequency  | Bandwidth for the X-axis magnetometer channel.          |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_x_raw                            | Raw X-axis magnetometer channel value.                  |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_y_calibbias                      | Calibration offset for the Y-axis magnetometer channel. |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_y_filter_low_pass_3db_frequency  | Bandwidth for the Y-axis magnetometer channel.          |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_y_raw                            | Raw Y-axis magnetometer channel value.                  |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_z_calibbias                      | Calibration offset for the Z-axis magnetometer channel. |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_z_filter_low_pass_3db_frequency  | Bandwidth for the Z-axis magnetometer channel.          |
++------------------------------------------+---------------------------------------------------------+
+| in_magn_z_raw                            | Raw Z-axis magnetometer channel value.                  |
++------------------------------------------+---------------------------------------------------------+
+
++------------------------------------------+-----------------------------------------------------+
+| Barometric pressure sensor related files | Description                                         |
++------------------------------------------+-----------------------------------------------------+
+| in_pressure0_calibbias                   | Calibration offset for barometric pressure channel. |
++------------------------------------------+-----------------------------------------------------+
+| in_pressure0_raw                         | Raw barometric pressure channel value.              |
++------------------------------------------+-----------------------------------------------------+
+| in_pressure0_scale                       | Scale for the barometric pressure sensor channel.   |
++------------------------------------------+-----------------------------------------------------+
+
+**Available for all supported devices:**
+
++-------------------------------------------+----------------------------------------------------------+
+| 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_x_calibscale                     | Calibration scale for the X-axis accelerometer channel.  |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_filter_low_pass_3db_frequency  | Bandwidth for the X-axis accelerometer channel.          |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_x_raw                            | Raw X-axis accelerometer channel value.                  |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_calibbias                      | Calibration offset for the Y-axis accelerometer channel. |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_calibscale                     | Calibration scale for the Y-axis accelerometer channel.  |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_y_filter_low_pass_3db_frequency  | Bandwidth for the Y-axis accelerometer channel.          |
++-------------------------------------------+----------------------------------------------------------+
+| 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_calibscale                     | Calibration scale for the Z-axis accelerometer channel.  |
++-------------------------------------------+----------------------------------------------------------+
+| in_accel_z_filter_low_pass_3db_frequency  | Bandwidth 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_x_calibscale                    | Calibration scale for the X-axis gyroscope channel.  |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_x_filter_low_pass_3db_frequency | Bandwidth for the X-axis gyroscope channel.          |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_x_raw                           | Raw X-axis gyroscope channel value.                  |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_calibbias                     | Calibration offset for the Y-axis gyroscope channel. |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_calibscale                    | Calibration scale for the Y-axis gyroscope channel.  |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_y_filter_low_pass_3db_frequency | Bandwidth for the Y-axis gyroscope channel.          |
++--------------------------------------------+------------------------------------------------------+
+| 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_calibscale                    | Calibration scale for the Z-axis gyroscope channel.  |
++--------------------------------------------+------------------------------------------------------+
+| in_anglvel_z_filter_low_pass_3db_frequency | Bandwidth 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_offset                  | Offset for the temperature sensor channel.|
++----------------------------------+-------------------------------------------+
+| 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.                         |
++-------------------------------+---------------------------------------------------------+
+
+The following table shows the adis16480 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. 16480, 16488, 16545, 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 adis16480 driver offers data for 7 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      |
++--------------------------------------+---------------------------+
+| Magnetic field along X, Y and Z axis | Gauss                     |
++--------------------------------------+---------------------------+
+| Barometric pressure                  | kilo Pascal               |
++--------------------------------------+---------------------------+
+
+Usage examples
+--------------
+
+Show device name:
+
+.. code-block:: bash
+
+	root:/sys/bus/iio/devices/iio:device0> cat name
+        adis16545-1
+
+Show accelerometer channels value:
+
+.. code-block:: bash
+
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_raw
+        1376728
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_y_raw
+        4487621
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_z_raw
+        262773792
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_scale
+        0.000000037
+
+- X-axis acceleration = in_accel_x_raw * in_accel_scale = 0.050938936 m/s^2
+- Y-axis acceleration = in_accel_y_raw * in_accel_scale = 0.166041977 m/s^2
+- Z-axis acceleration = in_accel_z_raw * in_accel_scale = 9.722630304 m/s^2
+
+Show gyroscope channels value:
+
+.. code-block:: bash
+
+        root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_x_raw
+        -1041702
+        root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_y_raw
+        -273013
+        root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_z_raw
+        2745116
+        root:/sys/bus/iio/devices/iio:device0> cat in_anglvel_scale
+        0.000000001
+
+- X-axis angular velocity = in_anglvel_x_raw * in_anglvel_scale = −0.001041702 rad/s
+- Y-axis angular velocity = in_anglvel_y_raw * in_anglvel_scale = −0.000273013 rad/s
+- Z-axis angular velocity = in_anglvel_z_raw * in_anglvel_scale = 0.002745116 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
+        4250.000000
+
+        root:/sys/bus/iio/devices/iio:device0> echo 1000 > sampling_frequency
+        1062.500000
+
+Set bandwidth for accelerometer channels:
+
+.. code-block:: bash
+
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_filter_low_pass_3db_frequency
+        0
+
+        root:/sys/bus/iio/devices/iio:device0> echo 300 > in_accel_x_filter_low_pass_3db_frequency
+        root:/sys/bus/iio/devices/iio:device0> cat in_accel_x_filter_low_pass_3db_frequency
+        300
+
+Show serial number:
+
+.. code-block:: bash
+
+        root:/sys/kernel/debug/iio/iio:device0> cat serial_number
+        0x000c
+
+Show product id:
+
+.. code-block:: bash
+
+        root:/sys/kernel/debug/iio/iio:device0> cat product_id
+        16545
+
+Show flash count:
+
+.. code-block:: bash
+
+        root:/sys/kernel/debug/iio/iio:device0> cat flash_count
+        88
+
+Show firmware revision:
+
+.. code-block:: bash
+
+        root:/sys/kernel/debug/iio/iio:device0> cat firmware_revision
+        1.4
+
+Show firmware date:
+
+.. code-block:: bash
+
+        root:/sys/kernel/debug/iio/iio:device0> cat firmware_date
+        09-23-2023
+
+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:
+
+- ADIS16545
+- ADIS16547
+
+However, when retrieving acceleration or gyroscope data using buffers, delta
+readings will not be available and vice versa. This is because the device only
+allows to read either acceleration and gyroscope data or delta velocity and
+delta angle data at a time and switching between these two burst data selection
+modes is time consuming.
+
+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 adis16545-1-dev0 > trigger/current_trigger
+        root:/sys/bus/iio/devices/iio:device0> cat trigger/current_trigger
+        adis16545-1-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::
+
+  root:/sys/bus/iio/devices/iio:device0> hexdump -C /dev/iio\:device0
+  ...
+  00006aa0  09 62 00 00 ff ff fc a4  00 00 01 69 00 03 3c 08  |.b.........i..<.|
+  00006ab0  09 61 00 00 00 00 02 96  00 00 02 8f 00 03 37 50  |.a............7P|
+  00006ac0  09 61 00 00 00 00 12 3d  00 00 0b 89 00 03 2c 0b  |.a.....=......,.|
+  00006ad0  09 61 00 00 00 00 1e dc  00 00 16 dd 00 03 25 bf  |.a............%.|
+  00006ae0  09 61 00 00 00 00 1e e3  00 00 1b bf 00 03 27 0b  |.a............'.|
+  00006af0  09 61 00 00 00 00 15 50  00 00 19 44 00 03 30 fd  |.a.....P...D..0.|
+  00006b00  09 61 00 00 00 00 09 0e  00 00 14 41 00 03 3d 7f  |.a.........A..=.|
+  00006b10  09 61 00 00 ff ff ff f0  00 00 0e bc 00 03 48 d0  |.a............H.|
+  00006b20  09 63 00 00 00 00 00 9f  00 00 0f 37 00 03 4c fe  |.c.........7..L.|
+  00006b30  09 64 00 00 00 00 0b f6  00 00 18 92 00 03 43 22  |.d............C"|
+  00006b40  09 64 00 00 00 00 18 df  00 00 22 33 00 03 33 ab  |.d........"3..3.|
+  00006b50  09 63 00 00 00 00 1e 81  00 00 26 be 00 03 29 60  |.c........&...)`|
+  00006b60  09 63 00 00 00 00 1b 13  00 00 22 2f 00 03 23 91  |.c........"/..#.|
+  ...
+
+See ``Documentation/iio/iio_devbuf.rst`` for more information about how buffered
+data is structured.
+
+4. IIO Interfacing Tools
+========================
+
+See ``Documentation/iio/iio_tools.rst`` for the description of the available IIO
+interfacing tools.
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 66fa69102e3a..4c13bfa2865c 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -19,5 +19,6 @@ Industrial I/O Kernel Drivers
 
    ad7944
    adis16475
+   adis16480
    bno055
    ep93xx_adc