Support ROHM BD79124 ADC. Quite usual stuff. 12-bit, 8-channel ADC with threshold monitoring. Except that: - each ADC input pin can be configured as a general purpose output. - manually starting an ADC conversion and reading the result would require the I2C _master_ to do clock stretching(!) for the duration of the conversion... Let's just say this is not well supported. - IC supports 'autonomous measurement mode' and storing latest results to the result registers. This mode is used by the driver due to the "peculiar" I2C when doing manual reads. I sent this as an RFC because I implemented the pin purposing (GPO/ADC) using pinmux - which I've never done for upstream stuff before. Hence it's better to ask if this makes sense, or if there is better way to go. Anyways, resulted drivers spread to 3 subsystems (MFD, pinctrl and IIO). Furthermore, the GPO functionality has not been (properly) tested. I'll do more testing for v2 if this pinmux approach is appropriate. Furthermore, because the ADC uses this continuous autonomous measuring, and because the IC keeps producing new 'out of window' IRQs if measurements are out of window - the driver disables the event when sending one. This prevents generating storm of events, but it also requires users to reconfigure / re-enable an event if they wish to continue monitoring after receiving one. Again I am not sure if this is the best way to handle such HW - so better to ask for an opinion than a nose bleed, right? Maybe the next version will no longer be a RFC :) --- Matti Vaittinen (5): dt-bindings: ROHM BD79124 ADC/GPO mfd: Add ROHM BD79124 ADC/GPO iio: adc: Support ROHM BD79124 ADC pinctrl: Support ROHM BD79124 pinmux / GPO MAINTAINERS: Add ROHM BD79124 ADC/GPO .../devicetree/bindings/mfd/rohm,bd79124.yaml | 111 +++ MAINTAINERS | 8 + drivers/iio/adc/Kconfig | 10 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/rohm-bd79124-adc.c | 890 ++++++++++++++++++ drivers/mfd/Kconfig | 12 + drivers/mfd/Makefile | 1 + drivers/mfd/rohm-bd79124.c | 165 ++++ drivers/pinctrl/Kconfig | 11 + drivers/pinctrl/Makefile | 1 + drivers/pinctrl/pinctrl-bd79124.c | 276 ++++++ include/linux/mfd/rohm-bd79124.h | 32 + 12 files changed, 1518 insertions(+) create mode 100644 Documentation/devicetree/bindings/mfd/rohm,bd79124.yaml create mode 100644 drivers/iio/adc/rohm-bd79124-adc.c create mode 100644 drivers/mfd/rohm-bd79124.c create mode 100644 drivers/pinctrl/pinctrl-bd79124.c create mode 100644 include/linux/mfd/rohm-bd79124.h base-commit: 5bc55a333a2f7316b58edc7573e8e893f7acb532 -- 2.48.1
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