diff --git a/cmake/Coverage.cmake b/cmake/Coverage.cmake
index dd1e6ce..e5fae00 100644
--- a/cmake/Coverage.cmake
+++ b/cmake/Coverage.cmake
@@ -4,6 +4,52 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
+#[===[.rst:
+Coverage CMake module
+---------------------
+
+Control flow
+^^^^^^^^^^^^
+
+Using the code coverage feature of the system starts with including
+``Coverage`` module. This will implicitly check if all the requirements for
+generating coverage are fulfilled. This includes checking the following
+conditions.
+
+- Compiler is GCC
+- lcov executables exist
+- ``c-picker-coverage-mapper`` is available
+
+As the next step it sets the compiler flags to make GCC to generate binaries
+with coverage information.
+
+
+Variables
+^^^^^^^^^
+
+The module sets the following variables while it's checking its prerequisites.
+
+.. cmake:variable:: LCOV_COMMAND
+
+Path of lcov executable
+
+.. cmake:variable:: GENHTML_COMMAND
+
+Path of genhtml executable which is part of the lcov package.
+
+.. cmake:variable:: CPICKER_COVERAGE_MAPPER_COMMAND
+
+Path of ``c-picker-coverage-mapper`` executable which is provided by c-picker
+pip package.
+
+
+Functions
+^^^^^^^^^
+
+The module also contains functions for setting up the coverage feature.
+
+#]===]
+
 include_guard(DIRECTORY)
 
 # Checking GCC
@@ -56,8 +102,51 @@
 	add_dependencies(${TARGET} ${TARGET}_target_${CUSTOM_TARGET_SUFFIX})
 endfunction()
 
-# Generates LCOV coverage info file by processing the .gcda and .gcno files.
-# The function also maps coverage of the c-picker generated files to the original source lines
+#[===[.rst:
+.. cmake:command:: coverage_generate
+
+  .. code-block:: cmake
+
+    coverage_generate(
+    	NAME test_name
+    	SOURCE_DIR source_directory
+    	BINARY_DIR binary_directory
+    	CPICKER_MAPPING_PATH c_picker_mapping_path
+    	OUTPUT_FILE output_file
+    )
+
+  The function outputs an lcov info file for further processing. It also handles
+  the remapping of the coverage of the c-picker generated files.
+
+  Control flow:
+
+  1. Running the ``lcov`` command for collecting the coverage data from the
+     available ``.gcda`` and ``.gcno`` files in the ``BINARY_DIR``.
+
+  2. The output of previous step is processed by ``c-picker-coverage-mapper``.
+     This will remap the coverage of files in ``CPICKER_MAPPING_PATH`` to the
+     original source files.
+
+  3. Adds the output file to the ``coverage`` target's dependency list.
+
+  Inputs:
+
+  ``NAME``
+    Test name included in lcov info file
+
+  ``SOURCE_DIR``
+    Directory of source files
+
+  ``BINARY_DIR``
+    Directory of the ``.gcda`` and ``.gcno`` files
+
+  ``CPICKER_MAPPING_PATH``
+    Path of c-picker generated files
+
+  ``OUTPUT_FILE``
+    Output lcov coverage info file
+
+#]===]
 function(coverage_generate)
 	set(_OPTIONS_ARGS)
 	set(_ONE_VALUE_ARGS NAME SOURCE_DIR BINARY_DIR CPICKER_MAPPING_PATH OUTPUT_FILE)
@@ -93,7 +182,33 @@
 	)
 endfunction()
 
-# Filters coverage info of files from the matching directory
+#[===[.rst:
+.. cmake:command:: coverage_filter
+
+  .. code-block:: cmake
+
+    coverage_filter(
+    	INPUT_FILE input_file
+    	OUTPUT_FILE output_file
+    	INCLUDE_DIRECTORY include_directory
+    )
+
+  The function filters the coverage data by including only the coverage of the
+  files of ``INCLUDE_DIRECTORY`` or its subdirectories. It adds the filtered
+  output file to the ``coverage`` target's dependency list.
+
+  Inputs:
+
+  ``INPUT_FILE``
+    Input lcov coverage info file
+
+  ``OUTPUT_FILE``
+    Output lcov coverage info file
+
+  ``INCLUDE_DIRECTORY``
+    Root directory of included files
+
+#]===]
 function(coverage_filter)
 	set(_OPTIONS_ARGS)
 	set(_ONE_VALUE_ARGS INPUT_FILE OUTPUT_FILE INCLUDE_DIRECTORY)
@@ -122,7 +237,30 @@
 	)
 endfunction()
 
-# Generated an HTML report from the LCOV info file
+#[===[.rst:
+.. cmake:command:: coverage_generate_report
+
+  .. code-block:: cmake
+
+    coverage_generate_report(
+    	INPUT_FILE input_file
+    	OUTPUT_DIRECTORY output_directory
+    )
+
+  The function generates a HTML coverage report from the lcov info file into
+  the ``OUTPUT_DIRECTORY``. It adds the output directory to the
+  ``coverage_report`` target's dependency list.
+
+  Inputs:
+
+  ``INPUT_FILE``
+    Input lcov coverage info file
+
+  ``OUTPUT_DIRECTORY``
+    Output directory of the coverage report where the ``index.html`` is the
+    root file of the report.
+
+#]===]
 function(coverage_generate_report)
 	set(_OPTIONS_ARGS)
 	set(_ONE_VALUE_ARGS INPUT_FILE OUTPUT_DIRECTORY)
diff --git a/cmake/FindLibClang.cmake b/cmake/FindLibClang.cmake
index c0eefc5..2b8c741 100644
--- a/cmake/FindLibClang.cmake
+++ b/cmake/FindLibClang.cmake
@@ -1,14 +1,22 @@
 #
-# Copyright (c) 2019, Arm Limited. All rights reserved.
+# Copyright (c) 2019-2020, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
 #[=======================================================================[.rst:
 FindLibClang
--------
+------------
 
-Finds the LibClang library.
+CMake module for finding the LibClang library.
+
+Control flow
+^^^^^^^^^^^^
+
+1. Running ``llvm-config`` if exists
+2. Searching for library at common places
+3. Searching in Windows registry if available
+
 
 Imported Targets
 ^^^^^^^^^^^^^^^^
@@ -18,6 +26,7 @@
 ``LibClang``
   The Clang library
 
+
 Result Variables
 ^^^^^^^^^^^^^^^^
 
diff --git a/cmake/UnitTest.cmake b/cmake/UnitTest.cmake
index 782dad9..d557eb0 100644
--- a/cmake/UnitTest.cmake
+++ b/cmake/UnitTest.cmake
@@ -4,14 +4,44 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
-include_guard(DIRECTORY)
+#[===[.rst:
+UnitTest CMake module
+---------------------
 
-# Trying to set CLANG_LIBRARY_PATH using the following methods
-# 1. Using cache or command line definition
-#    Show warning if environment variable is also set but has different value
-# 2. Copying the value of CLANG_LIBRARY_PATH environment variable if set
-# 3. find_package (llvm-config, common paths or Windows registry)
-# If none of the above steps succeeded CMake emits a fatal error and stops
+Control flow
+^^^^^^^^^^^^
+
+1. Setting :cmake:variable:`CLANG_LIBRARY_PATH`
+
+  1. Using :cmake:variable:`CLANG_LIBRARY_PATH` CMake variable
+
+  2. Using ``CLANG_LIBRARY_PATH`` environment variable
+
+  3. Trying to find by ``find_package`` function which calls :cmake:module:`FindLibClang`.
+
+2. Checking if ``c-picker`` command is available
+
+
+Variables
+^^^^^^^^^
+
+The module sets the following variables while it's checking its prerequisites.
+
+.. cmake:variable:: CLANG_LIBRARY_PATH
+
+libclang directory for c-picker
+
+.. cmake:variable:: CPICKER_COMMAND
+
+Path of c-picker executable which is part of the c-picker pip package.
+
+
+Functions
+^^^^^^^^^
+
+#]===]
+
+include_guard(DIRECTORY)
 
 set(CLANG_LIBRARY_PATH_HELP "libclang directory for c-picker")
 
@@ -42,15 +72,71 @@
 	message(FATAL_ERROR "Please install c-picker using pip")
 endif()
 
-# Global dependencies:
-#   Variables
-#     CPICKER_COMMAND: command of the c-picker
-#     CPICKER_CACHE_PATH: root directory of the c-picker generate files
-#     UNIT_TEST_COMMON_SOURCES: common source files for every test build
-#     CLANG_LIBRARY_PATH: libclang directory for c-picker
-#   Modules
-#     CTest module should be included in the root CMakeLists.txt before calling this function
+#[===[.rst:
+.. cmake:command:: unit_test_add_suite
 
+  .. code-block:: cmake
+
+    unit_test_add_suite(
+    	NAME test_name
+    	SOURCES source_files
+    	INCLUDE_DIRECTORIES include_directories
+    	COMPILE_DEFINITIONS defines
+    	DEPENDS dependencies
+    )
+
+  The ``unit_test_add_suite`` CMake function provides a convenient interface for
+  defining unit test suites. Basically its input is the test source files, include
+  paths and macro definitions and it internally does all the necessary steps to
+  have the test binary registered in CTest as a result.
+
+  Control flow:
+
+  1. Adding new executable named ``NAME``
+
+  2. Iterating throught ``SOURCES``
+
+     1. If it's a normal source file add to the executable's source list
+     2. If it's a YAML file add as a c-picker custom command and add the generated
+        file to the executable's source list
+
+  3. Setting include directories
+
+  4. Setting defines
+
+  5. Adding extra dependencies of the test build
+
+  6. Adding executable to the system as a test
+
+  Inputs:
+
+  ``NAME``
+    Unique name of the test suite
+
+  ``SOURCES`` (multi, optional)
+    Source files
+
+  ``INCLUDE_DIRECTORIES`` (multi, optional)
+    Include directories
+
+  ``COMPILE_DEFINITIONS`` (multi, optional)
+    Defines
+
+  ``DEPENDS`` (multi, optional)
+    Extra targets as dependencies of the test build
+
+  Global dependencies:
+
+  ``CPICKER_CACHE_PATH``
+    Root directory of the c-picker generated files
+
+  ``UNIT_TEST_COMMON_SOURCES``
+    Common source files for every test build
+
+  ``CTest``
+    Built-in testing module of CMake
+
+#]===]
 function(unit_test_add_suite)
 	set(_OPTIONS_ARGS)
 	set(_ONE_VALUE_ARGS NAME)