smart_amp: revamp to two-layer modular design structure

The motivation is depicted in
#7801

This commit revamps smart_amp component design to two-layer structure, i.e.
generic layer and inner model layer.

Generic layer is the common part of smart amp process which can be regarded
as the glue code interacting between SOF component ops and inner model.
While inner model may have various implementations respectively for
solution suppliers in a modular way.

Signed-off-by: Pin-chih Lin <johnylin@google.com>

Author: johnylin76

src/audio/smart_amp/CMakeLists.txt

@@ -10,4 +10,6 @@ else()
 sof_add_static_library(dsm ${CMAKE_CURRENT_LIST_DIR}/lib/release/dsm_lib/libdsm.a)
 endif()
 target_include_directories(sof PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include/dsm_api/inc)
+else()
+add_local_sources(sof smart_amp_passthru.c)
 endif()

src/audio/smart_amp/Kconfig

@@ -1,19 +1,39 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
-menu "Smart amplifier solutions"
-	visible if COMP_SMART_AMP
+if COMP_SMART_AMP
+
+choice
+        prompt "Smart Amplifier solution applied"
+        default PASSTHRU_AMP
+	help
+	  The selection for Smart Amplifier component implementation
+	  will depend on the Amplifier solution supplier. It is fair
+	  to treat the supported solutions as mutually exclusive ones.
+	  There should be no more than one solution selected per build
+	  config. When Smart Amplifier is present but no solution is
+	  supported, the passthrough mode will be applied as default.
+
+	config PASSTHRU_AMP
+		bool "Stream Passthrough"
+		help
+		  The default option as the passthrough mode while no other
+		  solution is applied. While selected, the feed-forward input
+		  frames will be passed to output after channel remapping. No
+		  gain or latency will be produced. In the meanwhile, the
+		  feedback input frames will be consumed but dropped directly.
 
 	config MAXIM_DSM
 		bool "Maxim DSM solution"
 		select MAXIM_DSM_STUB if COMP_STUBS
-		default n
 		help
 		  Select to apply Maxim DSM(Dynamic Speaker Management) solution
 		  for Smart Amplifier. As the third-party supply, the
 		  pre-compiled library provided by Maxim will be required for
 		  building the FW binary with this option enabled. The library
 		  itself should be statically linked with the SoF FW binary image.
 
+endchoice
+
 	config MAXIM_DSM_STUB
 		bool "Maxim DSM solution"
 		depends on MAXIM_DSM
@@ -22,5 +42,4 @@ menu "Smart amplifier solutions"
 		  Select to build the Maxim DSM adapter with a stub library. This
 		  should only be used for CI and testing.
 
-endmenu
-
+endif