[PATCH v3 0/2] iio: adc: Add Nuvoton MA35D1 EADC support

[Chi-Wen Weng <cwweng.linux@gmail.com>]

From: Chi-Wen Weng <cwweng@nuvoton.com>

Add devicetree binding and IIO driver support for the Enhanced
Analog-to-Digital Converter (EADC) found on Nuvoton MA35D1 SoCs.

The MA35D1 EADC is a 12-bit ADC controller with eight external analog
inputs. It supports single-ended conversion and four fixed differential
input pairs: 0-4, 1-5, 2-6 and 3-7.

The controller provides four interrupt outputs, ADINT0 through ADINT3.
ADINT0 through ADINT2 are associated with the corresponding conversion
interrupt flags. ADINT3 is shared by the ADIF3 conversion interrupt and
the ADCMPF0 through ADCMPF3 result-compare interrupt sources.

The initial driver uses sample module 0 and ADINT0 for conversion
completion. It supports direct reads and externally triggered buffered
capture. The driver supports an optional external reference supply and
uses the internal 1.6 V reference when no external reference is
provided.

The binding describes the optional DMA request and all four hardware
interrupt outputs, including the result-compare sources sharing ADINT3.
The initial driver does not use DMA or result-compare functionality.

Changes in v3:
- Document all four ADINT0 through ADINT3 hardware interrupt outputs and
  add interrupt-names.
- Document ADINT3 as the shared conversion and result-compare interrupt
  output.
- Remove the redundant minItems/maxItems constraints from the fixed
  interrupts items list.
- Rework the channel binding for the fixed differential pairs and use
  single-channel for single-ended inputs.
- Add #io-channel-cells so the EADC can be referenced by DT IIO
  consumers, and define the cell as the logical channel index.
- Add firmware-node channel translation so sparse or reordered channel
  child nodes are mapped by their logical channel index.
- Restrict unsupported generic ADC channel properties including bipolar,
  common-mode-channel, settling-time-us and oversampling-ratio.
- Explicitly configure INTPOS for end-of-conversion interrupt
  generation.
- Explicitly configure the ADINT0 sample-module source and clear unused
  sample-module routing.
- Reset the EADC control circuits during hardware initialization and
  clear inherited ADC interrupt enables, result-compare interrupt
  enables and sample-module trigger sources.
- Add timeout recovery using the EADC control-circuit reset, followed by
  IRQ synchronization and stale status/completion cleanup.
- Use iio_push_to_buffers_with_ts() for triggered buffered capture.
- Avoid mixing cleanup guards with goto paths in the trigger handler.
- Add ARCH_MA35 || COMPILE_TEST and HAS_IOMEM Kconfig dependencies.
- Drop redundant linux/bitops.h and linux/mod_devicetable.h includes.
- Use direct regmap helpers, explicit REGCACHE_NONE and
  regmap_assign_bits() where appropriate.
- Use fixed-width register offsets and kernel time/unit helpers.
- Use size_add() for channel array allocation.
- Request ADINT0 by interrupt name.
- Improve system suspend and resume handling.
- Address review comments from Jonathan Cameron, Rob Herring,
  Andy Shevchenko, Uwe Kleine-König and automated review/testing.

Changes in v2:
- Reworked the driver to use regmap.
- Added optional external reference supply support and IIO scale
  reporting.
- Added optional reset handling.
- Added externally triggered buffered capture.
- Added signed differential conversion handling.
- Added fixed differential-pair validation.
- Added system sleep support.
- Added optional DMA properties to the binding.

Patch 1 adds the devicetree binding.
Patch 2 adds the IIO driver.

Chi-Wen Weng (2):
  dt-bindings: iio: adc: Add Nuvoton MA35D1 EADC
  iio: adc: Add Nuvoton MA35D1 EADC driver

 .../bindings/iio/adc/nuvoton,ma35d1-eadc.yaml | 175 ++++
 drivers/iio/adc/Kconfig                       |  14 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/ma35d1_eadc.c                 | 849 ++++++++++++++++++
 4 files changed, 1039 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,ma35d1-eadc.yaml
 create mode 100644 drivers/iio/adc/ma35d1_eadc.c


base-commit: d89e1d186ec9271bf78e62771779e9fc03bf0fc3
-- 
2.25.1