[PATCH 0/2] Support for Avago APDS9306 Ambient Light Sensor

[Subhajit Ghosh <subhajit.ghosh@tweaklogic.com>]

This series adds support for Avago (Broadcom) APDS9306 Ambient Light
Sensor.

Datasheet: https://docs.broadcom.com/doc/AV02-4755EN

Following features are supported:
- I2C interface
- 2 channels - als and clear
- Raw data for als and clear channels
- Pocessed data (Lux) values for als channel
- Up to 20 bit resolution
- 20 bit data register for each channel
- Common Configurable items for both channels
    - Integration Time
    - Measurement Frequency
    - Scale
- High and Low threshold interrupts for each channel

- Selection of interrupt channels - als or clear
- Selection of interrupt mode - threshold or adaptive
- Level selection for adaptive threshold interrupts
- Persistence (Period) level selection for interrupts

Link: https://lore.kernel.org/all/20230411011203.5013-1-subhajit.ghosh@tweaklogic.com/
Link: https://patchwork.kernel.org/project/linux-iio/cover/20230411011203.5013-1-subhajit.ghosh@tweaklogic.com/

Sysfs structure:
root@stm32mp1:~# tree -I 'dev|name|of_node|power|subsystem|uevent' \
> /sys/bus/iio/devices/iio:device0/
/sys/bus/iio/devices/iio:device0/
|-- events
|   |-- in_illuminance_thresh_either_en
|   |-- in_intensity_clear_thresh_either_en
|   |-- thresh_adaptive_either_en
|   |-- thresh_adaptive_either_value
|   |-- thresh_adaptive_either_values_available
|   |-- thresh_either_period
|   |-- thresh_either_period_available
|   |-- thresh_falling_value
|   `-- thresh_rising_value
|-- in_illuminance_input
|-- in_illuminance_raw
|-- in_intensity_clear_raw
|-- integration_time
|-- integration_time_available
|-- sampling_frequency
|-- sampling_frequency_available
|-- scale
|-- scale_available
`-- waiting_for_supplier

RFC -> v0
 - DT binding review by Rob and Krzysztof:
  - Verified with dt_binding_check
  - Removed the last/redundant "bindings" word

 - Review by Andy:
  - Dropped blank line and reordered initial comments
  - Sorted header files
  - Added kernel-doc for the private structure
  - Removed regmap internal lock
  - Used regmap_read_poll_timeout() function instead of while loop
    in apds9306_read_data()
  - Applied fixes as per review

 - Review by Jonathan:
  - Updated apds9306_read_data() and apds9306_irq_handler() as per
    review. If interrupts are enabled together with userspace read
    of raw and processed adc values, then events can be pushed both
    by the interrupt handler and apds9306_read_data(). If the
    interrupt handler gets a data ready for read flag then it sets
    a flag in the private data structure which is used by 
    apds9306_read_data().
  - ABI update - In events, per cnannel enable for both
    channels, removing custom sysfs attributes for channel selection.
  - Added lux calculation. Page 4 of the datasheet has test results
    for only the default integration time at the default hardware gain.
    Normalized the values for all hardware gains and all supported
    integration times as per the part ID. I got consistent results
    when compared with a lux meter in the default range.
  - Other fixes as commented
  - Implemented IIO_GTS_HELPER
  - Shuffled functions for logical split and readability

Apologies for this huge delay in submitting this patch from RFC to v0.
I had a change of job and subsequent relocation.
Future revisions will not be delayed.

Subhajit Ghosh (2):
  dt-bindings: iio: light: Avago APDS9306
  iio: light: Add support for APDS9306 Light Sensor

 .../bindings/iio/light/avago,apds9306.yaml    |   49 +
 drivers/iio/light/Kconfig                     |   12 +
 drivers/iio/light/Makefile                    |    1 +
 drivers/iio/light/apds9306.c                  | 1381 +++++++++++++++++
 4 files changed, 1443 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/light/avago,apds9306.yaml
 create mode 100644 drivers/iio/light/apds9306.c


base-commit: b9ddbb0cde2adcedda26045cc58f31316a492215
-- 
2.34.1