Timestamp and PulSAR support for ad4000

Complement the ad4000 driver with a timestamp channel, a minor adjust in
transfer timing, and support for single-channel PulSAR devices.

Change log v3 -> v4
[IIO]
- No changes.
[Device tree]
- Sorted compatible strings in alphabetical order.
- Left only fallback compatibles in allOf check list for adi,sdi-pin property.
- Improved patch description with explanation about how the AD4000 and PulSAR
  devices are different.

Change log v2 -> v3
[IIO]
- Reverted to direct assignment of ad4000_time_spec structs.
[Device tree]
- No changes.

Change log v1 -> v2
- Added Suggested-by and Reviewed-by tags.
[IIO]
- Commented the removal of unused AD4000_TQUIET1_NS define in commit body.
- Made a common macro to assign ad4000_time_spec.
- Explicitly initialized PulSAR t_quiet2_ns with 0 as those don't need any quiet time.
- Improved PulSAR support commit description with more context.
- Dropped support for AD7694.
[Device tree]
- Made "cs" the default adi,sdi-pin value for PulSAR devices.

Link to v3: https://lore.kernel.org/linux-iio/cover.1732020224.git.ma...
Link to v2: https://lore.kernel.org/linux-iio/cover.1731953012.git.ma...
Link to v1: https://lore.kernel.org/linux-iio/cover.1731626099.git.ma...


Marcelo Schmitt (4):
  dt-bindings: iio: adc: adi,ad4000: Add PulSAR
  iio: adc: ad4000: Add timestamp channel
  iio: adc: ad4000: Use device specific timing for SPI transfers
  iio: adc: ad4000: Add support for PulSAR devices

 .../bindings/iio/adc/adi,ad4000.yaml          |  56 ++++
 drivers/iio/adc/ad4000.c                      | 311 +++++++++++++++---
 2 files changed, 316 insertions(+), 51 deletions(-)


base-commit: 9dd2270ca0b38ee16094817f4a53e7ba78e31567
-- 
2.45.2