This patch series adds basic audio support for Sophgo CV1800B,
as used on boards such as the Milk-V Duo.
The series introduces the I2S controller driver,
the DAC and ADC codec drivers, corresponding DT bindings,
and DTS updates to wire the components together.

The implementation is based on vendor documentation
and testing on real hardware.  This series relies on
recent fixes in the DesignWare AXI DMA support;
in particular, correct operation depends on
the DMA changes discussed at:
https://lore.kernel.org/all/20251214224601.598358-1-inochiama@gmail.com/ (local)
The current driver implementation supports a fixed audio configuration
of 48 kHz sample rate and only I2S protocol which is used in codecs.
The series has been tested on the Milk-V Duo 256M board using
the Sophgo SG2002 SoC. The implementation is expected to also work on
Milk-V Duo and Milk-V Module boards based on the SG2000 SoC,
as the audio and DMA blocks are closely related.

Known hardware limitation:
On CV1800B / SG2002, the I2S2 output pins cannot be enabled via 
pinctrl alone.  Due to SoC design constraints, the output path becomes 
functional only after additional vendor-specific register programming.
This series makes the limitation explicit and does not attempt 
to work around it implicitly via pinctrl or undocumented behavior.

Signed-off-by: Anton D. Stavinskii <redacted>
---
Changes in v4:
- fix issues with i2s bindings
- rename commit for codecs bindings
- make single bindings file for both adc and dac 
- Link to v3: https://lore.kernel.org/r/20260119-cv1800b-i2s-driver-v3-0-04006f4111d7@gmail.com (local)

Changes in v3:
- Kconfig: add SPDX.
- sound/soc/sophgo/cv1800b-tdm.c: add const to cv1800b_i2s_dai_template
- sound/soc/sophgo/cv1800b-tdm.c: drop unneeded debug message 
- sophgo,cv1800b-i2s.yaml: removed address-cells
- sophgo,cv1800b-i2s.yaml: reword for commit message and header
- sophgo,cv1800b-i2s.yaml: fixed dma-names node
- sophgo,cv1800b-i2s.yaml: clocks min-items fixed 
- codecs bindings: squash
- codecs bindings: unevaluatedProperties: false, dropped redundant
  description 
- fixed build error revealed by test_bot 
- cv180x.dtsi: removed address-cells in i2s nodes
- Link to v2: https://lore.kernel.org/r/20260118-cv1800b-i2s-driver-v2-0-d10055f68368@gmail.com (local)

Changes in v2:
- Updated cover letter.
- codec nodes moved to cv1800x.dtsi with status=disabled
- the commit with dts example for 256M board was removed
- added details in commit messages

- Link to v1: https://lore.kernel.org/r/20260115-cv1800b-i2s-driver-v1-0-e8b22b8578ab@gmail.com (local)

---
Anton D. Stavinskii (6):
      ASoC: dt-bindings: sophgo,cv1800b: add I2S/TDM controller
      ASoC: sophgo: add CV1800B I2S/TDM controller driver
      ASoC: dt-bindings: sophgo,cv1800b: add ADC/DAC codec
      ASoC: sophgo: add CV1800B internal ADC codec driver
      ASoC: sophgo: add CV1800B internal DAC codec driver
      riscv: dts: sophgo: dts nodes for i2s tdm modules

 .../bindings/sound/sophgo,cv1800b-codecs.yaml      |  46 ++
 .../bindings/sound/sophgo,cv1800b-i2s.yaml         |  67 ++
 arch/riscv/boot/dts/sophgo/cv180x-dmamux.h         |  57 ++
 arch/riscv/boot/dts/sophgo/cv180x.dtsi             |  55 ++
 sound/soc/Kconfig                                  |   1 +
 sound/soc/Makefile                                 |   1 +
 sound/soc/sophgo/Kconfig                           |  46 ++
 sound/soc/sophgo/Makefile                          |   5 +
 sound/soc/sophgo/cv1800b-sound-adc.c               | 322 +++++++++
 sound/soc/sophgo/cv1800b-sound-dac.c               | 204 ++++++
 sound/soc/sophgo/cv1800b-tdm.c                     | 716 +++++++++++++++++++++
 11 files changed, 1520 insertions(+)
---
base-commit: 7a52965b6976c936f413eebeee3f78c6faf09012
change-id: 20260115-cv1800b-i2s-driver-4f17836dec56

Best regards,
-- 
Anton D. Stavinskii [off-list ref]