[FEATURE][meta] Use Zephyr native interfaces

[kv2019i]

This is a meta issue to track work to move SOF code to use Zephyr native interfaces. The task is two-fold:

1. move (audio) application code to use native Zephyr interfaces (this is the primary focus, affects all SOF users and configurations)
2. move driver and hw platform code to Zephyr (this is secondary as new platforms will be Zephyr-only -- current we have some Intel and IMX platforms that support both XTOS and Zephyr and separate set of cleanups are needed for these platforms)

Change in brief: SOF application code will transition to Zephyr application interfaces. Change is done incrementally so that build with the "in-tree XTOS" continuous to work.

Guard rails:

• code in sof/src/audio is the primary application code, should only use Zephyr interfaces
• drivers in sof/src/drivers should be moved to Zephyr upstream
• arch code in sof/src/arch is not used for SOF Zephyr builds, this is only for XTOS builds
• rtos interface provided via <rtos/foo.h> interface with implmentation in
  - sof/zephyr/include/rtos/
  - sof/xtos/include/rtos/

Transition tools:

• sof/zephyr/wrapper.c - xtos-to-zephyr wrapping that was used for initial introduction of Zephyr. this will grow smaller and smaller and eventually be removed
• sof/src/arch/xtos-wrapper/ - zephyr-to-xtos wrapper used to maintain capability to build SOF app code on XTOS
• when application code moves to use native Zephyr interface, XTOS fallback should be added in src/xtos/include/ (example xtos/include/rtos/spinlock.h )

Ongoing work for generic code (affects all SOF configurations):

• Module init with native Zephyr interface [FEATURE] Implement module_init in Zephyr builds #5406 [SOF2.5]
• Spinlocks Convert spinlock to Zephyr API #5286
• System clock for timing Wallclock Clocks timer: Align SOF timer API with Zephyr #5393
• Logging, partially done in sof: replace log calls with zephyr logging api #5707
• Wait k_usleep() and k_msleep() wrappers for xtos #5770
• Zephyr DAI interface - partially done in dma: switch to native Zephyr API for dw-dma & HDA #5610
• Zephyr DMA interface - partially started in dma: switch to native Zephyr API for dw-dma & HDA #5610
• Split of RTOS headers for XTOS/Zephyr rtos: abstraction: partition RTOS logic into separate directories #6161 [SOF2.5]
• Probe interface to use native Zephyr DMA interface - [BUG] unable to enable probes logging for MTL #7218 and Enable probes on MTL #7989
• Zephyr cache API z_xtensa_cache_*() -- dependency to xtensa: use generic cache API zephyrproject-rtos/zephyr#50136
• irq_local_*able() to to Zephyr irq_lock() / irq_unlock()
• make CONFIG_SOF_ZEPHYR_STRICT_HEADERS the default [BUG] make CONFIG_SOF_ZEPHYR_STRICT_HEADERS the default #9015
• cleanup overlap between Zephyr and SOF lib dma.h interfaces [FEATURE] Clean up SOF DMA interface(s) #9561

Ongoing work for SOF platform layer (affects all SOF configurations):

• Platform.h - [FEATURE][Zephyr] Clarify expectations of platform.h for Zephyr SOF builds #7248
• implement clk.h without platform layer [FEATURE][Zephyr] implement clk.h with native Zephyr interface and drop platform clk.h #9541
• implement mailbox.h without platform layer [FEATURE][Zephyr] replace mailbox.h with a IPC abstraction #9697
• implement cpu.h without platform layer -- zephyr: lib/cpu.h: remove dependency to platform layer #9648
• implement dai.h without platform layer -- remove platform lib/dai.h from SOF Zephyr builds #9653
• implement dma.h without platform layer -- zephyr: lib/dma.h: limit use of platform/lib/dma.h #9667
• implement pm_runtime.h without platform layer -- zephyr: decouple from platform pm_runtime.h interface #9495

Ongoing work for specific platforms (Intel cAVS, NXP IMX)

• PM runtime move to Zephyr PM model (Intel ACE done, Intel cAVS in zephyr: cavs: use zephyr pm, clk and dma glue #7183 )
• [FEATURE][Zephyr] Move all hw init code from platform_init() to Zephyr #5602

From @dbaluta - For NXP we have on roadmap to port to Zephyr:

• DAIs (SAI and ESAI);
• EDMA;
• SDMA;
• Interrupt controller (irq steer).

[hongshui3000]

is there any plan to move code in sof/src/platform/ to zephyr？
I want development drivers and platforms to be out of tree

[lgirdwood]

is there any plan to move code in sof/src/platform/ to zephyr？ I want development drivers and platforms to be out of tree

Yes - we are just working out the stages for this. Topic at TSC tomorrow.

[hlleng]

is there any plan to move code in sof/src/platform/ to zephyr？ I want development drivers and platforms to be out of tree

Yes - we are just working out the stages for this. Topic at TSC tomorrow.

Is there something news to share after TSC？

[lgirdwood]

@lenghonglin apologies, I and some other TSC member were travelling last week.

Please see minutes here. https://github.com/orgs/thesofproject/teams/steering-committee/discussions/31

[lgirdwood]

@kv2019i we should add the DAI/DMA integration here too ?

[kv2019i]

Marked multiple items as done. Added one new item for platform code init.

[lgirdwood]

@abonislawski @mwasko @dbaluta any items you can add/update here ?