[v3,0/4] iio: adc: ad4000: Add SPI offload support

Message

Marcelo Schmitt March 26, 2025, 1:24 p.m. UTC

This patch series extends the ad4000 driver to support SPI offloading.
In addition to that, ad4000 IIO documentation is expanded to:
- list PulSAR parts supported by the ad4000 driver.
- describe some characteristics of AD4000 IIO device.
- describe changes when SPI offload is being used.

Change log v2 -> v3
- Dropped patch 1 of v2 series and reverted buffer endianness and SPI transfer
  bits_per_word configurations to the way they were in v1.
- Removed dummy transfer in ad4000_prepare_offload_turbo_message().
- Unified offload message preparation.
- Removed spi->cs_hold.value to use cs_inactive to set CNV/CS high time.
- Adjusted max sample rate for AD7983 and AD7984.
- Dropped AD4000_TCONV_NS and made all time related constants a time_spec field.
- Removed _offl param from _CHANNELS() macros and added a comment about that.
- Commented IIO_BE check in ad4000_prepare_3wire_mode_message().
- Now using predisable to balance with postenable.
- Put spi/offload/consumer.h include right after spi/spi.h.
- Removed unrelated brackets in info_mask_separate_available assignment
- Added blank line after if.

Change log v1 -> v2
- Fixed passing inappropriate pointer instead of ret to dev_err_probe()
- [new patch] Set transfer bits_per_word to have data in CPU endianness
- Set iio_dev num_channels close to where channels is set.
- Complement offload message comment about first sample being invalid
- Document why the first buffer sample is invalid when offloading
- Added blank line before a 'simple return'.

Link to v2: https://lore.kernel.org/linux-iio/[e-mail]/
Link to v1: https://lore.kernel.org/linux-iio/[e-mail]/

v3 was tested and worked with the following setups
- ADAQ4003 on CoraZ7 with SPI offload support;
- AD7687 on CoraZ7 with SPI offload support;
- AD7687 on rpi (no SPI offload support).
The Linux image ran on cora was built from IIO testing branch.
The Linux image ran on rpi was built from rpi tree rpi-6.14.y branch with
some adaptations to cope with old iio_device_claim_direct_mode() and addition
of the following patches
iio: adc: ad4000: Stop using iio_device_claim_direct_scoped()
spi: add basic support for SPI offloading
spi: offload: add support for hardware triggers
dt-bindings: trigger-source: add generic PWM trigger source
spi: offload-trigger: add PWM trigger driver
spi: add offload TX/RX streaming APIs
iio: buffer-dmaengine: split requesting DMA channel from allocating buffer
iio: buffer-dmaengine: add devm_iio_dmaengine_buffer_setup_with_handle()

Marcelo Schmitt (4):
  iio: adc: ad4000: Add support for SPI offload
  Documentation: iio: ad4000: Add new supported parts
  Documentation: iio: ad4000: Add IIO Device characteristics section
  Documentation: iio: ad4000: Describe offload support

 Documentation/iio/ad4000.rst |  86 +++++++-
 drivers/iio/adc/Kconfig      |   7 +-
 drivers/iio/adc/ad4000.c     | 405 ++++++++++++++++++++++++++++++++---
 3 files changed, 463 insertions(+), 35 deletions(-)


base-commit: af94f401e26f686f7391ce79b38a6129417c22dc
prerequisite-patch-id: 3d517eef53a799adba5922815fe684b913e36773