math: Introduce a DSP basicmath subsystem with a cmsis backend

Introduce an API mirroring the CMSIS-DSP's basicmath. If CMSIS_DSP is
enabled, then it will by default be used as a backend. Developers may
opt into a custom backend by setting CONFIG_DSP_BACKEND_CMSIS=n. If
done, the application must provide `zdsp_backend/dsp.h` and optionally
implement the functions in its own .c files.

Signed-off-by: Yuval Peress <[email protected]>

CODEOWNERS

@@ -756,6 +756,7 @@ scripts/build/gen_image_info.py @tejlmand
 /subsys/debug/gdbstub.c @ceolin
 /subsys/dfu/ @de-nordic @nordicjm
 /subsys/disk/ @jfischer-no
+/subsys/dsp/ @yperess
 /subsys/tracing/ @nashif
 /subsys/debug/asan_hacks.c @aescolar @daor-oti
 /subsys/demand_paging/ @dcpleung @nashif

MAINTAINERS.yml

@@ -324,6 +324,17 @@ CMSIS API layer:
  - "area: CMSIS API Layer"
  - "area: Portability"
 
+DSP subsystem:
+ status: maintained
+ maintainers:
+ - stephanosio
+ - yperess
+ files:
+ - subsys/dsp/
+ - tests/subsys/dsp/
+ labels:
+ - "area: DSP"
+
 CMSIS-DSP integration:
  status: maintained
  maintainers:
@@ -334,7 +345,6 @@ CMSIS-DSP integration:
  - modules/Kconfig.cmsis_dsp
  - tests/benchmarks/cmsis_dsp/
  - tests/lib/cmsis_dsp/
- - tests/subsys/dsp/
  labels:
  - "area: CMSIS-DSP"
 

doc/develop/api/overview.rst

@@ -316,3 +316,7 @@ between major releases are available in the :ref:`zephyr_release_notes`.
  * - :ref:`watchdog_api`
  - Stable
  - 1.0
+
+ * - :ref:`zdsp_api`
+ - Experimental
+ - 3.3

doc/services/dsp/index.rst

@@ -0,0 +1,61 @@
+.. _zdsp_api:
+
+Digital Signal Processing (DSP)
+###############################
+
+.. contents::
+ :local:
+ :depth: 2
+
+The DSP API provides an architecture agnostic way for signal processing.
+Currently, the API will work on any architecture but will likely not be
+optimized. The status of the various architectures can be found below:
+
++--------------+-------------+
+| Architecture | Status |
++--------------+-------------+
+| ARC | Unoptimized |
+| ARM | Optimized |
+| ARM64 | Optimized |
+| MIPS | Unoptimized |
+| NIOS2 | Unoptimized |
+| POSIX | Unoptimized |
+| RISCV | Unoptimized |
+| RISCV64 | Unoptimized |
+| SPARC | Unoptimized |
+| X86 | Unoptimized |
+| XTENSA | Unoptimized |
++--------------+-------------+
+
+Using zDSP
+**********
+
+zDSP provides various backend options which are selected automatically for the
+application. By default, including the CMSIS module will enable all
+architectures to use the zDSP APIs. This can be done by setting::
+
+ CONFIG_CMSIS_DSP=y
+
+If your application requires some additional customization, it's possible to
+enable :kconfig:option:`CONFIG_DSP_BACKEND_CUSTOM` which means that the
+application is responsible for providing the implementation of the zDSP
+library.
+
+Optimizing for your architecture
+********************************
+
+If your architecture is showing as ``Unoptimized``, it's possible to add a new
+zDSP backend to better support it. To do that, a new Kconfig option should be
+added to `subsys/dsp/Kconfig`_ along with the required dependencies and the
+``default`` set for ``DSP_BACKEND`` Kconfig choice.
+
+Next, the implementation should be added at ``subsys/dsp/<backend>/`` and
+linked in at `subsys/dsp/CMakeLists.txt`_.
+
+API Reference
+*************
+
+.. doxygengroup:: math_dsp
+
+.. _subsys/dsp/Kconfig: https://github.com/zephyrproject-rtos/zephyr/blob/main/subsys/dsp/Kconfig
+.. _subsys/dsp/CMakeLists.txt: https://github.com/zephyrproject-rtos/zephyr/blob/main/subsys/dsp/CMakeLists.txt

doc/services/index.rst

@@ -10,6 +10,7 @@ OS Services
  crypto/index
  debugging/index.rst
  device_mgmt/index
+ dsp/index.rst
  file_system/index.rst
  formatted_output.rst
  ipc/index.rst

doc/zephyr.doxyfile.in

@@ -2316,6 +2316,7 @@ PREDEFINED = __DOXYGEN__ \
  CONFIG_ERRNO \
  CONFIG_FLASH_JESD216_API \
  CONFIG_FLASH_PAGE_LAYOUT \
+ CONFIG_FP16 \
  CONFIG_FPU \
  CONFIG_FPU_SHARING \
  CONFIG_GDBSTUB \