sensors: generate attributes/channels/triggers

Add code generation for the sensor attribute, channel, and trigger
enums. Included in this is the ability to query the sensor's
information statically using the compatible string similar to how
devicetree does it.

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

doc/CMakeLists.txt

@@ -96,6 +96,12 @@ endfunction()
 #-------------------------------------------------------------------------------
 # Doxygen (standalone)
 
+set(CMAKE_C_ARCHIVE_CREATE "<CMAKE_C_COMPILER> cr <TARGET> <OBJECTS>")
+set(CMAKE_C_ARCHIVE_FINISH  "<CMAKE_C_COMPILER> s <TARGET>")
+add_library(zephyr_interface INTERFACE)
+include(${ZEPHYR_BASE}/drivers/sensor/codegen.cmake)
+set_target_properties(zephyr_sensor.constants PROPERTIES LINKER_LANGUAGE C)
+
 set(DOXY_OUT ${CMAKE_CURRENT_BINARY_DIR}/doxygen)
 set(DOXYFILE_IN ${CMAKE_CURRENT_LIST_DIR}/zephyr.doxyfile.in)
 set(DOXYFILE_OUT ${CMAKE_CURRENT_BINARY_DIR}/zephyr.doxyfile)
@@ -116,6 +122,8 @@ set_target_properties(
     ADDITIONAL_CLEAN_FILES "${DOXY_OUT}"
 )
 
+add_dependencies(doxygen zephyr_sensor.constants.__generate_constants)
+
 #-------------------------------------------------------------------------------
 # devicetree
 
@@ -149,6 +157,8 @@ set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${GEN_DEVICETREE_
 #-------------------------------------------------------------------------------
 # html
 
+set(SPHINXOPTS_EXTRA ${SPHINXOPTS_EXTRA} -D sensor_yaml_files="${sensor_yaml_files}")
+
 add_doc_target(
   html
   COMMAND ${CMAKE_COMMAND} -E env ${SPHINX_ENV} OUTPUT_DIR=${DOCS_HTML_DIR}
@@ -172,7 +182,7 @@ set_target_properties(
     ADDITIONAL_CLEAN_FILES "${DOCS_SRC_DIR};${DOCS_HTML_DIR};${DOCS_DOCTREE_DIR}"
 )
 
-add_dependencies(html devicetree)
+add_dependencies(html devicetree zephyr_sensor.constants.__generate_constants)
 
 #-------------------------------------------------------------------------------
 # html-live
@@ -202,7 +212,7 @@ set_target_properties(
     ADDITIONAL_CLEAN_FILES "${DOCS_SRC_DIR};${DOCS_HTML_DIR};${DOCS_DOCTREE_DIR}"
 )
 
-add_dependencies(html-live devicetree)
+add_dependencies(html-live devicetree zephyr_sensor.constants.__generate_constants)
 #-------------------------------------------------------------------------------
 # pdf
 
@@ -230,7 +240,7 @@ set_target_properties(
     ADDITIONAL_CLEAN_FILES "${DOCS_SRC_DIR};${DOCS_LATEX_DIR};${DOCS_DOCTREE_DIR}"
 )
 
-add_dependencies(latex devicetree)
+add_dependencies(latex devicetree zephyr_sensor.constants.__generate_constants)
 
 if(LATEX_PDFLATEX_FOUND AND LATEXMK)
   if(WIN32)
@@ -252,7 +262,7 @@ if(LATEX_PDFLATEX_FOUND AND LATEXMK)
     USES_TERMINAL
   )
 
-  add_dependencies(pdf latex)
+  add_dependencies(pdf latex zephyr_sensor.constants.__generate_constants)
 endif()
 
 #-------------------------------------------------------------------------------

doc/conf.py

@@ -249,7 +249,11 @@
 doxyrunner_doxyfile = ZEPHYR_BASE / "doc" / "zephyr.doxyfile.in"
 doxyrunner_outdir = ZEPHYR_BUILD / "doxygen"
 doxyrunner_fmt = True
-doxyrunner_fmt_vars = {"ZEPHYR_BASE": str(ZEPHYR_BASE), "ZEPHYR_VERSION": version}
+doxyrunner_fmt_vars = {
+    "ZEPHYR_BASE": str(ZEPHYR_BASE),
+    "CMAKE_BINARY_DIR": str(ZEPHYR_BUILD.parent),
+    "ZEPHYR_VERSION": version,
+}
 doxyrunner_outdir_var = "DOXY_OUT"
 
 # -- Options for zephyr.doxybridge plugin ---------------------------------

doc/hardware/peripherals/sensor/index.rst

@@ -97,10 +97,77 @@ Implementing Read and Decode
 * MUST implement :c:type:`sensor_get_decoder_t` returning the
   :c:struct:`sensor_decoder_api` for that device type.
 
+Adding your ``sensor.yaml``
+===========================
+
+Sensor YAML files can be added to enhance your driver writing experience. Each
+sensor can introduce a ``sensor.yaml`` file which follows the schema described
+in `pw_sensor`_. In tree, the file will automatically be picked up by the build
+system and entries will be created for your driver. See the example at
+``tests/drivers/sensor/generator/`` for the macro usage, you can do things
+like:
+
+* Get the number of attributes, channels, and triggers supported by a specific
+  compatible string.
+* Get the number of instances of a specific channel of a sensor.
+* Check if a driver supports setting a specific attribute/channel pair.
+* Automatically index your drivers into the Zephyr documentation
+
+The primary use case for these is to verify that a DT entry's compatible value
+supports specific requirements. For example:
+
+* Assume we're building a lid angle calculation which requires 2
+  accelerometers. These accelerometers will be specified in the devicetree
+  using the chosen nodes so we can access them via ``DT_CHOSEN(lid_accel)``
+  and ``DT_CHOSEN(base_accel)``.
+* We can now run a static assert like
+  ``BUILD_ASSERT(SENSOR_SPEC_CHAN_INST_COUNT(DT_PROP(DT_CHOSEN(lid_accel), compatible), accel_xyz) > 0);``
+
+Additional features are in development and will allow drivers to:
+
+* Generate boilerplate code for the sensor API such as attribute set/get,
+  submit, etc.
+* Generate common config/data struct definitions.
+* Abstract the bus API so you can read/write registers without worrying about
+  i2c/spi/etc.
+* Optimize memory allocation based to YAML metadata. Using the static data
+  available in the ``sensor.yaml`` file, we will be able to allocate the right
+  size buffer for streaming and one-shot reading APIs as well as client side
+  buffers.
+
+Adding sensors out of tree
+--------------------------
+
+Zephyr supports adding sensors from modules. There are 3 CMake variables that
+should be updated to make that happen:
+
+* ``ZEPHYR_EXTRA_SENSOR_YAML_FILES``: this is a cmake list containing full
+  paths to sensor YAML files that are not in the Zephyr tree.
+* ``ZEPHYR_EXTRA_SENSOR_INCLUDE_PATHS``: this is a cmake list containing full
+  paths to directories which contains custom attributes, channels, triggers, or
+  units. These paths are directories which the ``zephyr_sensor_library`` cmake
+  function will use to find definition files which are included in your sensor
+  YAML file. It's similar to header include paths.
+* ``ZEPHYR_EXTRA_SENSOR_DEFINITION_FILES``: this is a cmake list containing
+  full paths to files containing custom attributes, channels, triggers, or
+  units. The file list is used to determine when the sensor library needs to be
+  rebuilt.
+
+Why ``sensor.yaml`` files?
+--------------------------
+
+* We already use YAML files to describe boards.
+* They allow us to add metadata per driver type. See below for a comparison to
+  devicetree.
+* They're portable. Downstream users may implement additional generators to do
+  new things.
+
 .. _sensor-api-reference:
 
 API Reference
 ***************
 
 .. doxygengroup:: sensor_interface
 .. doxygengroup:: sensor_emulator_backend
+
+.. _`pw_sensor`: https://pigweed.dev/pw_sensor/py/

doc/zephyr.doxyfile.in

@@ -972,6 +972,7 @@ WARN_LOGFILE           =
 
 INPUT                  = @ZEPHYR_BASE@/doc/_doxygen/mainpage.md \
                          @ZEPHYR_BASE@/doc/_doxygen/groups.dox \
+                         @CMAKE_BINARY_DIR@/zephyr_sensor.constants/ \
                          @ZEPHYR_BASE@/kernel/include/kernel_arch_interface.h \
                          @ZEPHYR_BASE@/include/zephyr/arch/cache.h \
                          @ZEPHYR_BASE@/include/zephyr/sys/atomic.h \

drivers/sensor/CMakeLists.txt

@@ -64,6 +64,8 @@ add_subdirectory_ifdef(CONFIG_VEAA_X_3 veaa_x_3)
 add_subdirectory_ifdef(CONFIG_VOLTAGE_DIVIDER voltage_divider)
 add_subdirectory_ifdef(CONFIG_TACH_ENE_KB1200 ene_tach_kb1200)
 
+include(codegen.cmake)
+
 zephyr_syscall_header(${ZEPHYR_BASE}/include/zephyr/drivers/sensor.h)
 
 zephyr_library()

drivers/sensor/asahi_kasei/akm09918c/sensor.yaml

@@ -0,0 +1,24 @@
+# Copyright (c) 2024 Google Inc
+# SPDX-License-Identifier: BDS-3-Clause
+
+deps:
+  - "drivers/sensor/attributes.yaml"
+  - "drivers/sensor/channels.yaml"
+  - "drivers/sensor/triggers.yaml"
+  - "drivers/sensor/units.yaml"
+compatible:
+  org: "asahi-kasei"
+  part: "akm09918c"
+supported-buses:
+  - i2c
+channels:
+  magn_xyz: []
+  magn_x: []
+  magn_y: []
+  magn_z: []
+attributes:
+  - attribute: "sampling_frequency"
+    channel: "magn_xyz"
+    units: "frequency"
+extras:
+  doc-link: "asahi_kasei_akm09918c_driver"

drivers/sensor/attributes.yaml

@@ -0,0 +1,68 @@
+# Copyright (c) 2024 Google Inc
+# SPDX-License-Identifier: BDS-3-Clause
+
+attributes:
+  sampling_frequency:
+    name: "sampling rate"
+    description: >
+      Sensor sampling frequency, i.e. how many times a second the sensor takes a measurement.
+  lower_thresh:
+    name: "lower threshold"
+    description: "Lower threshold for trigger."
+  upper_thresh:
+    name: "upper threshold"
+    description: "Upper threshold for trigger."
+  slope_th:
+    name: "any motion threshold"
+    description: "Threshold for any-motion (slope) trigger."
+  slope_dur:
+    name: "slope value threshold duration"
+    description: >
+      Duration for which the slope values needs to be outside the threshold for the trigger to
+      fire.
+  hysteresis:
+    name: "hysteresis"
+    description: "Hysteresis for trigger thresholds."
+  oversampling:
+    name: "oversampling factor"
+    description: "Oversampling factor"
+  full_scale:
+    name: "range"
+    description: "Sensor range, in SI units."
+  offset:
+    name: "value offset"
+    description: >
+      The sensor value returned will be altered by the amount indicated by offset: final_value =
+      sensor_value + offset.
+  calib_target:
+    name: "calibration target"
+    description: >
+      Calibration target. This will be used by the internal chip's algorithms to calibrate itself
+      on a certain axis, or all of them.
+  configuration:
+    name: "operating mode"
+    description: "Configure the operating modes of a sensor."
+  calibration:
+    name: "calibration value"
+    description: "Set a calibration value needed by a sensor."
+  feature_mask:
+    name: "enabled/disabled feature"
+    description: "Enable/disable sensor features"
+  alert:
+    name: "alert threshold"
+    description: "Alert threshold or alert enable/disable"
+  ff_dur:
+    name: "free-fall duration"
+    description: >
+      Free-fall duration represented in milliseconds. If the sampling frequency is changed during
+      runtime, this attribute should be set to adjust freefall duration to the new sampling
+      frequency.
+  batch_duration:
+    name: "batch duration"
+    description: "Hardware batch duration in ticks"
+  gain:
+    name: "gain"
+    description: "Configure the gain of a sensor."
+  resolution:
+    name: "resolution"
+    description: "Configure the resolution of a sensor."

drivers/sensor/bosch/bma4xx/sensor.yaml

@@ -0,0 +1,34 @@
+# Copyright (c) 2024 Google Inc
+# SPDX-License-Identifier: BDS-3-Clause
+
+deps:
+  - "drivers/sensor/attributes.yaml"
+  - "drivers/sensor/channels.yaml"
+  - "drivers/sensor/triggers.yaml"
+  - "drivers/sensor/units.yaml"
+compatible:
+  org: "bosch"
+  part: "bma4xx"
+supported-buses:
+  - i2c
+  - spi
+description: |
+  Sensor driver implementation for bma422 and bma423.
+channels:
+  accel_x: []
+  accel_y: []
+  accel_z: []
+  accel_xyz: []
+  die_temp: []
+attributes:
+  - attribute: "sampling_frequency"
+    channel: "accel_xyz"
+    units: "frequency"
+  - attribute: "full_scale"
+    channel: "accel_xyz"
+    units: "acceleration"
+  - attribute: "offset"
+    channel: "accel_xyz"
+    units: "acceleration"
+extras:
+  doc-link: "bosch_bma4xx_driver"

drivers/sensor/bosch/bmi160/sensor.yaml

@@ -0,0 +1,50 @@
+# Copyright (c) 2024 Google Inc
+# SPDX-License-Identifier: BDS-3-Clause
+
+deps:
+  - "drivers/sensor/attributes.yaml"
+  - "drivers/sensor/channels.yaml"
+  - "drivers/sensor/triggers.yaml"
+  - "drivers/sensor/units.yaml"
+compatible:
+  org: "bosch"
+  part: "bmi160"
+supported-buses:
+  - i2c
+  - spi
+description: |
+  Sensor driver implementation for bmi160.
+channels:
+  accel_x: []
+  accel_y: []
+  accel_z: []
+  accel_xyz: []
+  gyro_x: []
+  gyro_y: []
+  gyro_z: []
+  gyro_xyz: []
+  die_temp: []
+attributes:
+  - attribute: "sampling_frequency"
+    channel: "accel_xyz"
+    units: "frequency"
+  - attribute: "sampling_frequency"
+    channel: "gyro_xyz"
+    units: "frequency"
+  - attribute: "full_scale"
+    channel: "accel_xyz"
+    units: "acceleration"
+  - attribute: "full_scale"
+    channel: "gyro_xyz"
+    units: "angular_velocity"
+  - attribute: "offset"
+    channel: "accel_xyz"
+    units: "acceleration"
+  - attribute: "offset"
+    channel: "gyro_xyz"
+    units: "angular_velocity"
+triggers:
+  - data_ready
+  - delta
+extras:
+  doc-link: "bosch_bmi160_driver"