pipeline: introduce declarative static topology definition and loader

[lgirdwood]

Summary

Add support for declarative static audio pipelines in Sound Open Firmware.
In microcontroller, hostless, and standalone embedded environments (such as ESP32-P4/S3/C6, PJRC Teensy 4.1, Nordic nRF54, RP2350, smart speakers, and audio bridges), there is no dynamic IPC host driver (Linux ALSA/SoundWire or Windows) to construct topologies at runtime.

Key Additions & Features

1. Declarative Topology Structures & Macros (<sof/audio/pipeline/static_pipeline.h>):

   • Full Doxygen API docblocks covering all structures, fields, enums, macros, and public APIs.
   • Comprehensive sample rate bitmasks (SOF_STATIC_RATE_*) aligned with SOF_RATE_* and format bitmasks (SOF_STATIC_FMT_*) aligned with enum sof_ipc_frame.
   • Concise constructor macros (SOF_STATIC_MODULE, SOF_STATIC_MODULE_RATE_CONV, SOF_STATIC_ENDPOINT_DAI, SOF_STATIC_ENDPOINT_USB) for clean declarative pipeline definition.

2. Ops-Driven Decoupled Architecture:

   • Generic headers and loader engine have zero per-module logic or dependencies.
   • Audio processing modules define and self-register their static operations (struct sof_static_module_ops) providing .create, .apply_volume, .apply_switch, and .apply_enum callbacks directly in their own source files (SRC, ASRC, Volume/Gain, Level Multiplier, Selector, EQ IIR, DRC, and TDFB) using DECLARE_STATIC_MODULE_OPS().

3. Generic Module Registry & Base IPC4 Config Synthesizer (static_pipeline_modules.c):

   • Generic ops registry with structured error logging on lookup failures.
   • Base IPC4 config synthesizer (sof_static_init_base_cfg) generating standard IPC4 base module configurations (struct ipc4_base_module_cfg) on behalf of the absent host, calculating IBS/OBS and channel mapping from declarative capabilities and periods.

4. Dynamic Format & Rate Negotiation:

   • Dynamically resolves primary stream sample rates from topology descriptors, removing hardcoded defaults.
   • Supports sample rate converters (SRC/ASRC), up/down mixers, and format conversions with per-buffer rate/channel inheritance.

5. Static Topology Loader Engine (static_pipeline_loader.c):

   • Instantiates native SOF pipelines, components, intermediate buffers, routes, and kcontrols directly at boot.
   • Component preparation and parameter negotiation to ensure all processing modules reach ready state prior to streaming.
   • Comprehensive inline comments on every code block explaining the action and rationale.

6. Dedicated Pipeline Control & Trigger Safety:

   • Separate start/stop routines (sof_static_pipeline_start, sof_static_pipeline_stop).
   • Strict abort on pipeline_prepare() failure preventing triggers on uninitialized circular buffers.
   • UAC2 terminal dispatch routing directly to modular start/stop helpers.
   • Decoupled custom kcontrol callback handler for board- and platform-specific controls.

7. Kconfig & Build Integration:

   • CONFIG_STATIC_PIPELINE Kconfig option and CMakeLists integration.

8. Developer Documentation:

   • Comprehensive architectural guide, API references, and step-by-step tutorial with multi-rate SRC examples in src/audio/pipeline/README.md.