On Tue, Apr 26, 2022 at 3:11 PM Andrea Merello <andrea.merello@xxxxxxxxx> wrote: > > From: Andrea Merello <andrea.merello@xxxxxx> > > This series (tries to) add support for Bosch BNO055 IMU to Linux IIO > subsystem. It is made up several patches: > > 1/14 to 6/14: add some IIO modifiers, and their documentation, to the IIO > core layer, in order to being able to expose the linear > acceleration and Euler angles among standard attributes. > Also update the IIO event monitor tool > > 7/14: fix binary attributes didn't work with IIO > > 8/14 to 11/14: add the core IIO BNO055 driver and documentation for sysfs > attributes and DT bindings > > 12/14: adds serdev BNO055 driver to actually use the IMU via serial line > > 13/14: adds I2C BNO055 driver to actually use the IMU via I2C wiring > > 14/14: add a documentation file that describe the bno055 driver and > specifically the calibration FWIW, Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> for non-commented patches (12 out of 14 AFAICS). > Differences wrt v4: > - be more tolerant wrt unrecognized chip IDs > - rename 'serial_number' attribute in 'serialnumber' > - fix missing NULL variable initialization > - use sign_extend32() instead of s16 casting where appropriate > - fix quaternion unit > - minor stuff (e.g. comments..) > - reduce (slightly) locking in serdev driver > - rework tracepoint support (e.g. remove dedicated config option) > > Differences wrt other BNO055 drivers: > > Previously at least another driver for the very same chip has been posted > to the Linux ML [0], but it has been never merged, and it seems no one > cared of it since quite a long time. > > This driver differs from the above driver on the following aspects: > > - This driver supports also serial access (to be reliable, reset pin is > required to be wired) > > - The above driver tried to support all IMU HW modes by allowing to > choose one in the DT, and adapting IIO attributes accordingly. This > driver does not rely on DT for this, instead settings are done via > sysfs attributes. All IIO attributes are always exposed; more on this > later on. This driver however supports only a subset of the > HW-supported modes. > > - This driver has some support for managing the IMU calibration > > Supported operation modes: > > - AMG (accelerometer, magnetometer and gyroscope) mode, which provides > raw (uncalibrated) measurements from the said sensors, and allows for > setting some parameters about them (e.g. filter cut-off frequency, max > sensor ranges, etc). > > - Fusion mode, which still provides AMG measures, while it also provides > other data calculated by the IMU (e.g. rotation angles, linear > acceleration, etc). In this mode user has no freedom to set any sensor > parameter, since the HW locks them. Autocalibration and correction is > performed by the IMU. > > IIO attributes exposing sensors parameters are always present, but in > fusion modes the available values are constrained to just the one used by > the HW. This is reflected in the '*_available' IIO attributes. > > Trying to set a not-supported value always falls back to the closest > supported one, which in this case is just the one in use by the HW. > > IIO attributes for unavailable measurements (e.g. Euler angles in AMG > mode) can't be read (return -EBUSY, or refuse to enable buffer). > > IMU calibration: > > The IMU supports for two sets of calibration parameters: > > - SIC matrix. user-provided; this driver doesn't currently support it > > - Offset and radius parameters. The IMU automatically finds out them when > it is running in fusion mode; supported by this driver. > > The driver provides access to autocalibration flags (i.e. you can known > if the IMU has successfully autocalibrated) and to calibration data blob. > The user can save this blob in a "firmware" file (i.e. in /lib/firmware) > that the driver looks for at probe time. If found, then the IMU is > initialized with this calibration data. This saves the user from > performing the calibration procedure every time (which consist of moving > the IMU in various way). > > The driver looks for calibration data file using two different names: > first a file whose name is suffixed with the IMU unique ID is searched > for; this is useful when there is more than one IMU instance. If this > file is not found, then a "generic" calibration file is searched for > (which can be used when only one IMU is present, without struggling with > fancy names, that changes on each device). > > In AMG mode the IIO 'offset' attributes provide access to the offsets > from calibration data (if any), so that the user can apply them to the > accel, angvel and magn IIO attributes. In fusion mode they are not needed > and read as zero. > > > Access protocols and serdev module: > > The serial protocol is quite simple, but there are tricks to make it > really works. Those tricks and workarounds are documented in the driver > source file. > > The core BNO055 driver tries to group readings in burst when appropriate, > in order to optimize triggered buffer operation. The threshold for > splitting a burst (i.e. max number of unused bytes in the middle of a > burst that will be throw away) is provided to the core driver by the > lowlevel access driver (either serdev or I2C) at probe time. > > [0] https://www.spinics.net/lists/linux-iio/msg25508.html > > Andrea Merello (14): > iio: add modifiers for linear acceleration > iio: document linear acceleration modifiers > iio: event_monitor: add linear acceleration modifiers > iio: add modifers for pitch, yaw, roll > iio: document pitch, yaw, roll modifiers > iio: event_monitor: add pitch, yaw and roll modifiers > iio: add support for binary attributes > iio: imu: add Bosch Sensortec BNO055 core driver > iio: document bno055 private sysfs attributes > iio: document "serialnumber" sysfs attribute > dt-bindings: iio/imu: Add Bosch BNO055 > iio: imu: add BNO055 serdev driver > iio: imu: add BNO055 I2C driver > docs: iio: add documentation for BNO055 driver > > Documentation/ABI/testing/sysfs-bus-iio | 25 + > .../ABI/testing/sysfs-bus-iio-bno055 | 81 + > .../bindings/iio/imu/bosch,bno055.yaml | 59 + > Documentation/iio/bno055.rst | 50 + > Documentation/iio/index.rst | 2 + > drivers/iio/imu/Kconfig | 1 + > drivers/iio/imu/Makefile | 1 + > drivers/iio/imu/bno055/Kconfig | 25 + > drivers/iio/imu/bno055/Makefile | 10 + > drivers/iio/imu/bno055/bno055.c | 1710 +++++++++++++++++ > drivers/iio/imu/bno055/bno055.h | 12 + > drivers/iio/imu/bno055/bno055_i2c.c | 57 + > drivers/iio/imu/bno055/bno055_ser_core.c | 560 ++++++ > drivers/iio/imu/bno055/bno055_ser_trace.h | 104 + > drivers/iio/industrialio-core.c | 10 +- > include/uapi/linux/iio/types.h | 7 +- > tools/iio/iio_event_monitor.c | 6 + > 17 files changed, 2718 insertions(+), 2 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-bno055 > create mode 100644 Documentation/devicetree/bindings/iio/imu/bosch,bno055.yaml > create mode 100644 Documentation/iio/bno055.rst > create mode 100644 drivers/iio/imu/bno055/Kconfig > create mode 100644 drivers/iio/imu/bno055/Makefile > create mode 100644 drivers/iio/imu/bno055/bno055.c > create mode 100644 drivers/iio/imu/bno055/bno055.h > create mode 100644 drivers/iio/imu/bno055/bno055_i2c.c > create mode 100644 drivers/iio/imu/bno055/bno055_ser_core.c > create mode 100644 drivers/iio/imu/bno055/bno055_ser_trace.h > > -- > 2.17.1 -- With Best Regards, Andy Shevchenko
