[PATCH v3 0/2] iio: adc: Add support for Texas Instruments ADS112C04

[Kyle Hsieh <kylehsieh1995@gmail.com>]

This patch series introduces support for the Texas Instruments ADS112C04
Analog-to-Digital Converters.

The ADS112C04 (16-bit) is precision, low-power, delta-sigma ADCs with
an I2C interface. They feature a flexible input multiplexer supporting
single-ended and differential measurements, a programmable gain amplifier,
and an internal voltage reference.

Note: While this chip shares similarities with the ADS112C14 (currently 
being upstreamed by David Lechner), the register maps and feature sets 
are sufficiently different to warrant a separate driver. However, the
DT bindings and channel parsing logic have been aligned with the
ADS112C14 conventions.

This initial submission provides a minimal feature set (single-shot 
conversions and basic DRDY interrupt) covering current use cases.

Signed-off-by: Kyle Hsieh <kylehsieh1995@gmail.com>
---
Changes in v3:
- dt-bindings: iio: adc: ti,ads112c04:
  - Resolved dt_binding_check errors by removing redundant $ref for
    standard unit suffixes and fixing YAML array syntax.
  - Added full hardware capability descriptions (excitation-channels,
    excitation-current-nanoamp, burn-out-current-nanoamp,
    reference-sources) as suggested by David Lechner.
  - Restricted the reg maximum to 11 and updated the regex to
    ^channel@[0-9a-b]$ to accurately reflect the 12 possible MUX
    combinations.

- iio: adc: ti-ads112c04:
  - Transitioned all I2C read/write wrappers to use SMBus APIs
    (i2c_smbus_read_byte_data, i2c_smbus_read_word_data, etc.) to
    gracefully handle I2C errors, NACKs, and Repeated Starts, addressing
    feedback from Joshua Crofts and Jonathan Cameron.
  - Added forward compatibility checks in probe() and parse_channels()
    using dev_err_probe() to return -EOPNOTSUPP for unimplemented DT
    properties.
  - Reverted devm_request_irq() flags to 0 to let the driver inherit the
    trigger type strictly from the DT, per Jonathan Cameron's advice.
  - Reduced the data wait timeout to 100ms, reflecting the chip's slowest
    data rate of 20 SPS.
  - Fixed #include alphabetical sorting, grouped <linux/iio/*> headers,
    and added missing headers.
  - Fixed variable declaration ordering (reverse xmas tree) and updated
    variable naming to vref_mV (SI unit exception).
  - Optimized GPIO reset logic using GPIOD_OUT_HIGH.
- Link to v2: https://lore.kernel.org/r/20260731-ti-ads112c04-driver-v2-0-aab0168c3c01@gmail.com

Changes in v2:
- Replaced `vref-supply` with `refp-supply` and `refn-supply` to accurately reflect hardware.
- Refactored the driver to dynamically parse channel configurations and routing from DT child nodes.
- Modernized the driver using kernel macros.
- Handled endianness elegantly.
- Added hardware reset fallback logic.
- Inherited IRQ trigger type from device tree instead of hardcoding.
- Fixed a bug where the MUX software cache could desync from hardware if the I2C write failed.
- Added strict return value checking for all I2C writes during probe.
- Updated the `i2c_device_id` array to use C99 named initializers.
- Link to v1: https://lore.kernel.org/r/20260728-ti-ads112c04-driver-v1-0-475efe4e2b78@gmail.com

---
Kyle Hsieh (2):
      dt-bindings: iio: adc: ti,ads112c04: Add binding for ADS112C04
      iio: adc: ti-ads112c04: Add support for TI ADS112C04

 .../devicetree/bindings/iio/adc/ti,ads112c04.yaml  | 146 +++++++
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/ti-ads112c04.c                     | 423 +++++++++++++++++++++
 4 files changed, 580 insertions(+)
---
base-commit: 4539944e515183668109bdf4d0c3d7d228383d88
change-id: 20260724-ti-ads112c04-driver-be7e89047834

Best regards,
-- 
Kyle Hsieh <kylehsieh1995@gmail.com>