Add an IIO driver for the MEMSIC MMC5983MA 3-axis magnetometer over
I2C. The driver provides raw magnetic field readings with
per-measurement SET/RESET offset cancellation, giving 18-bit output
with a full-scale range of +/-8 Gauss.
MMC5983MA is not register-compatible with the existing MEMSIC
magnetometer drivers. It has a different register map, 18-bit output
data format, and I2C/SPI transport support.
Tested on a Raspberry Pi 2B with the sensor on I2C-1 at 0x30.
The initial driver implements the validated I2C single-measurement path.
Other chip features are left for future work:
- SPI transport: the binding describes SPI wiring, but driver support is
left for follow-up validation of the SPI command and SET/RESET
sequencing.
- Temperature channel: left until the temperature output behavior is
better validated.
- Continuous measurement mode and Auto SET/RESET: left until the
interaction between CMM, TM_M, Meas_M_Done, and SET/RESET sequencing
is better understood.
- Saturation/self-test bits and BW/decimation tuning: not exposed until
their behavior can be described reliably through stable IIO ABI.
The driver uses a conservative 500 us post-SET/RESET delay before
starting the following measurement. The datasheet describes a 500 ns
SET/RESET coil pulse, but testing showed that a longer software delay is
needed before taking the next measurement.
Changes since v2:
- Driver:
- refactored SET/RESET coil pulse into mmc5983_pulse_coil() helper
- used USEC_PER_MSEC for regmap_read_poll_timeout and fsleep constants
- DT binding:
- removed redundant comments from examples
- Cover letter:
- added "why a new driver" explanation
- Collected Reviewed-by and Acked-by tags
Changes since v1:
- DT binding:
- added SPI bus support, interrupts, and vddio-supply
- made vdd-supply required
- switched to unevaluatedProperties with spi-peripheral-props ref
- Driver:
- replaced scoped_guard() with guard(mutex) in a case block
- added datasheet page references for timing values
- changed product ID mismatch from probe failure to dev_info()
- hardcoded the IIO device name
- added trailing commas
- added local struct device and regmap pointers in mmc5983_init()
- MAINTAINERS:
- split binding and driver F: entries across the relevant patches
Vladislav Kulikov (2):
dt-bindings: iio: magnetometer: add MEMSIC MMC5983MA
iio: magnetometer: add driver for MEMSIC MMC5983MA
.../iio/magnetometer/memsic,mmc5983.yaml | 63 ++++
MAINTAINERS | 7 +
drivers/iio/magnetometer/Kconfig | 11 +
drivers/iio/magnetometer/Makefile | 1 +
drivers/iio/magnetometer/mmc5983.c | 345 ++++++++++++++++++
5 files changed, 427 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/memsic,mmc5983.yaml
create mode 100644 drivers/iio/magnetometer/mmc5983.c
base-commit: 7fd2df204f342fc17d1a0bfcd474b24232fb0f32
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2.43.0