[PATCH v6 0/4] iio: adc: Add support for LTC2378 and similar ADCs

[Marcelo Schmitt <marcelo.schmitt@analog.com>]

This patch series adds support for LTC2378 and similar low noise, low power,
high speed, successive approximation register (SAR) ADCs. These ADCs are similar
among each other, varying mainly on the amount of precision bits, maximum sample
rate, and input configuration (either fully differential or pseudo-differential).

Patch 1 adds device tree documentation for LTC2378.

Patch 2 enables single-shot sample read with a GPIO connected to the LTC2378 CNV pin.

Patch 3 enables high-speed data captures with SPI offloading.
The setup is similar to AD4030, with a specialized PWM generator being used both
for SPI offload triggering and conversion start signaling.

Patch 4 enables running buffered data captures without SPI offloading.

Even though these parts are somewhat similar to AD4000, the wiring configuration
for LTC parts is different as well as the available HDL for high speed sample
rate mode. Because of that, I propose creating a new device driver for
supporting LTC2378-like devices.

Specifications can be found at:
https://www.analog.com/media/en/technical-documentation/data-sheets/233818fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236416fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236418f.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236716fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236718f.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236816f.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236818f.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/236918fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237016fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237616fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237618fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237620fb.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237716fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237718fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237720fb.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237816fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237818fa.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237820fb.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/237918fb.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/238016fb.pdf

Previous submissions:
  v5: https://lore.kernel.org/linux-iio/cover.1783028033.git.marcelo.schmitt@analog.com/
  v4: https://lore.kernel.org/linux-iio/cover.1782397418.git.marcelo.schmitt@analog.com/
  v3: https://lore.kernel.org/linux-iio/cover.1781661028.git.marcelo.schmitt@analog.com/
  v2: https://lore.kernel.org/linux-iio/cover.1779976379.git.marcelo.schmitt@analog.com/
  v1: https://lore.kernel.org/linux-iio/cover.1779117444.git.marcelo.schmitt1@gmail.com/

Change log v5 -> v6:
[DT]
- Dropped single compatible strings for parts that have a fall back so dt-schema
  can enforces the fallback compliance.
[IIO]
- Added a comment to clarify IIO buffer storagebits and endianness for the
  offload use case.
- Added comment to clarify CPU endianness is used when device native BE is not.
- Protected single sample read procedure with a mutex.
- Dropped mod_devicetable.h, include device-id/spi.h device-id/of.h instead.
- Used iwyu to add missing #includes and dropped superfluous ones.
- Used pahole to minimize memory holes in LTC2378 data structures.

With best regards,
Marcelo


Marcelo Schmitt (4):
  dt-bindings: iio: adc: Add ltc2378
  iio: adc: ltc2378: Add support for LTC2378-20 and similar ADCs
  iio: adc: ltc2378: Enable high-speed data capture
  iio: adc: ltc2378: Enable triggered buffer data capture

 .../bindings/iio/adc/adi,ltc2378.yaml         | 170 ++++
 MAINTAINERS                                   |   8 +
 drivers/iio/adc/Kconfig                       |  19 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/ltc2378.c                     | 821 ++++++++++++++++++
 5 files changed, 1019 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ltc2378.yaml
 create mode 100644 drivers/iio/adc/ltc2378.c


base-commit: 093239070573637ad2b4cb56abc9c4c7ee109294
-- 
2.53.0