Doc: Add support for Sphinx documentation build.

Technical documentation of TF-M is captured in GitHub flavored
markdown files. This change add support for building HTML and
PDF output of these files using the Sphinx tool.

Change-Id: I8be11256f2c654c248b1974974a5de6190ca0fc3
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
diff --git a/cmake/FindPythonModules.cmake b/cmake/FindPythonModules.cmake
new file mode 100644
index 0000000..bb8d4fb
--- /dev/null
+++ b/cmake/FindPythonModules.cmake
@@ -0,0 +1,64 @@
+#-------------------------------------------------------------------------------
+# Copyright (c) 2019, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+#-------------------------------------------------------------------------------
+
+#FindPythonModules
+#-----------
+#This module checks availability of Python modules.
+#
+#This module has the following parameters:
+#   PYTHON_EXECUTABLE - Location of python interpreter.
+#   COMPONENTS        - List of python modules to look for.
+#
+#This module defines the following variables:
+#   PY_XXX       - Cached string variable with the location of the module.
+#   PY_XXX_FOUND - Set if the module is available.
+#
+#   Where XXX is the upper case name of the module.
+#
+#Examples
+#   To look for m2r and report error if not found
+#       find_module(PythonModules COMPONENTS m2r)
+#       if (PY_M2R_FOUND)
+#           do something
+#       endif()
+#
+#   To look for m2r and do not report error if not found
+#       find_module(PythonModules OPTIONAL_COMPONENTS m2r)
+#       if (PY_M2R_FOUND)
+#           do something
+#       endif()
+
+if(NOT DEFINED PYTHON_EXECUTABLE)
+	message(FATAL_ERROR "FindPythonModules: mandatory parameter PYTHON_EXECUTABLE is missing.")
+endif()
+
+include(Common/Utils)
+
+foreach(_mod ${PythonModules_FIND_COMPONENTS})
+	string(TOUPPER ${_mod} _mod_upper)
+	string(REPLACE "-" "_" _modname "${_mod}")
+	if (NOT PY_${_mod_upper})
+		#Execute python and try to include the module.
+		execute_process(
+			COMMAND ${PYTHON_EXECUTABLE} -c "import ${_modname}; print(${_modname}.__file__);"
+			RESULT_VARIABLE ${_mod}_status
+			OUTPUT_VARIABLE ${_mod}_path
+			ERROR_QUIET
+			OUTPUT_STRIP_TRAILING_WHITESPACE)
+		#If suceeded
+		if(NOT ${_mod}_status)
+			#Avoid trouble with directory separator on windows.
+			win_fix_dir_sep(PATH ${_mod}_path)
+			set("PY_${_mod_upper}" "${${_mod}_path}" CACHE STRING
+				"Location of Python module ${_mod}")
+		endif()
+	endif()
+	find_package_handle_standard_args(PY_${_mod_upper}
+		FOUND_VAR PY_${_mod_upper}_FOUND
+		REQUIRED_VARS PY_${_mod_upper}
+		FAIL_MESSAGE "Can not find Python module ${_mod}")
+endforeach()