[PATCH v2 00/15] iio: adc: ad4134: Enable greater sample rate data capture

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

Extend AD4134 support to enable greater sample rate data capture. To achieve
that, provide control of digital filter type selection. The default filter
type on device power up only supports sample rates up to 374 kSPS. In addition
to that, enable interfacing with AD4134 in SPI 4-wire mode that can support
reading ADC sample data through multiple wires. Finally, use SPI offloading
to speed up data transfers at up to 1.49 MSPS.

Features being added:
- Data filter type selection.
- Triggered buffer data read.
- SPI 4-wire mode.
- High speed data capture with SPI offloading.
- Device tree doc updates to reflect previously missing chip characteristics.

Minor improvements (introduced before the new features):
- Sign extend sample data. [NEW FIXES PATCH]
- Fix typo in vendor name.
- Drop import to empty name space.
- Update include list to comply with IWYU principles.
- Serialize single-read operations.
- Run shorter transfers when CRC is disabled.


The updates in v2 tackle all applicable suggestions from reviewers and from
automated tests/reviews/AI.

Change log v1 -> v2:
[device tree]
- Set default for adi,spi-mode property.
- Added '#daisy-chained-devices' property.
- Documented constraints for adi,spi-mode + #daisy-chained-devices combinations.
- Documented external multiplexer usage. [NEW PATCH]
[IIO]
- Sign extended ADC sample data for correct delivery of negative ADC input
  difference.
- Now also fixing Analog Devices possessive suffix usage.
- Added {} to delimit scoped mutex usage context in single-sample read.
- Tidy up code for filter select support. 
- Fixed IIO scan buffer size and single-read loop.
- No longer memcpy() with same pointer for source and destination.
- Always delimit guard()() with a blank line.
- Fail on unsupported adi,spi-mode.
- Now properly initializing access mode mutex.
- Highlighted usage of hardware external to AD4134 chip.
- Added comment about mux state switch logic.
- Suggestive name for auxiliary local variables.
- Updated preparation flow for ad4134_data_read().
- Error out on min I/O + offload config (currently not being supported).
- Preserved triggered buffer setup callbacks.
- Used pahole to reduce memory holes in ad4134_state struct.
- Improved PWM setup readability, update allowed scan_mask codestyle.
- Docs: Improved AD4134 connection diagrams.

Previous submissions:
  v1: https://lore.kernel.org/linux-iio/cover.1788368334.git.marcelo.schmitt@analog.com/


With best regards,
Marcelo

Marcelo Schmitt (15):
  iio: adc: ad4134: Sign extend sample data
  iio: Fix typo in vendor name
  iio: adc: ad4134: Drop import to empty name space
  iio: adc: ad4134: Update include list to comply with IWYU principles
  iio: adc: ad4134: Serialize single-read operations
  iio: adc: ad4134: Run shorter transfers when CRC is disabled
  iio: adc: ad4134: Add support for digital filter type selection
  iio: adc: ad4134: Support buffered data read
  dt-bindings: iio: adc: adi,ad4134: Document SPI connection mode
  dt-bindings: iio: adc: adi,ad4134: Document external multiplexer usage
  iio: adc: ad4134: Support SPI 4-wire mode
  dt-bindings: iio: adc: adi,ad4134: Document PWM usage
  dt-bindings: iio: adc: adi,ad4134: Add high data throughput example
  iio: adc: ad4134: Support high-speed data capture
  Docs: iio: Add AD4134

 .../bindings/iio/adc/adi,ad4134.yaml          | 111 ++-
 Documentation/iio/ad4134.rst                  | 130 +++
 Documentation/iio/ade9000.rst                 |   2 +-
 Documentation/iio/adis16475.rst               |   2 +-
 Documentation/iio/adis16480.rst               |   2 +-
 Documentation/iio/adis16550.rst               |   2 +-
 Documentation/iio/adxl313.rst                 |   2 +-
 Documentation/iio/adxl345.rst                 |   2 +-
 Documentation/iio/adxl380.rst                 |   2 +-
 Documentation/iio/index.rst                   |   1 +
 MAINTAINERS                                   |   1 +
 drivers/iio/adc/Kconfig                       |  20 +-
 drivers/iio/adc/ad4134.c                      | 751 +++++++++++++++++-
 drivers/iio/dac/ad3552r.c                     |   2 +-
 14 files changed, 985 insertions(+), 45 deletions(-)
 create mode 100644 Documentation/iio/ad4134.rst


base-commit: 9c464e7473f762cee4c031a09da04f65a1c65d49
-- 
2.53.0