MLECO-1860: Support for Arm GNU Embedded Toolchain

This patch enables compilation of ML use cases bare-metal applications
using Arm GNU Embedded Toolchain. The GNU toolchain can be used instead
of the Arm Compiler that was already supported.

The GNU toolchain is also set as the default toolchain when building
applications for the MPS3 target.

Note: The version of GNU toolchain must be 10.2.1 or higher.

Change-Id: I5fff242f0f52d2db6c75d292f9fa990df1aec978
Signed-off-by: Kshitij Sisodia <kshitij.sisodia@arm.com>
diff --git a/scripts/cmake/toolchains/bare-metal-armclang.cmake b/scripts/cmake/toolchains/bare-metal-armclang.cmake
new file mode 100644
index 0000000..0a86eb6
--- /dev/null
+++ b/scripts/cmake/toolchains/bare-metal-armclang.cmake
@@ -0,0 +1,134 @@
+#----------------------------------------------------------------------------
+#  Copyright (c) 2021 Arm Limited. All rights reserved.
+#  SPDX-License-Identifier: Apache-2.0
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#----------------------------------------------------------------------------
+# specify the cross compiler
+set(CMAKE_C_COMPILER                armclang)
+set(CMAKE_CXX_COMPILER              armclang)
+set(CMAKE_C_LINKER_PREFERENCE       armlink)
+set(CMAKE_ASM_LINKER_PREFERENCE     armlink)
+set(CMAKE_ASM_COMPILER              armasm)
+set(CMAKE_ASM_COMPILER_AR           armar)
+
+set(CMAKE_CROSSCOMPILING            true)
+set(CMAKE_SYSTEM_NAME               Generic)
+
+set(MIN_ARM_CLANG_VERSION           6.14)
+
+# Skip compiler test execution
+set(CMAKE_C_COMPILER_WORKS          1)
+set(CMAKE_CXX_COMPILER_WORKS        1)
+set(PLATFORM_HAL                    1)
+
+if (NOT DEFINED CMAKE_SYSTEM_PROCESSOR)
+    set(CMAKE_SYSTEM_PROCESSOR      cortex-m55)
+endif()
+
+if (CMAKE_SYSTEM_PROCESSOR STREQUAL cortex-m55)
+    # Flags for cortex-m55
+    set(CPU_COMPILE_DEF             CPU_CORTEX_M55)
+    set(CPU_NAME                    ${CMAKE_SYSTEM_PROCESSOR})
+    set(FLOAT_ABI                   hard)
+    set(ARM_MATH_DSP                1)
+    set(ARM_MATH_LOOPUNROLL         1)
+    set(CPU_LINK_OPT                "--cpu=8.1-M.Main.dsp")
+elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL cortex-m33)
+    # Flags for cortex-m33 to go here
+endif()
+
+set(${CPU_COMPILE_DEF}              1)
+
+# Warning options
+add_compile_options(
+    -Wall
+    -Wextra
+    -Wvla)
+
+# General purpose compile options:
+add_compile_options(
+    -funsigned-char
+    -fno-function-sections
+    "$<$<COMPILE_LANGUAGE:CXX>:-fno-unwind-tables;-fno-rtti;-fno-exceptions>")
+
+# Arch compile options:
+add_compile_options(
+    -mthumb
+    -mcpu=${CPU_NAME}
+    -mfloat-abi=${FLOAT_ABI}
+    --target=arm-arm-non-eabi
+    -mlittle-endian
+    -MD)
+
+# Compile definitions:
+add_compile_definitions(
+    PLATFORM_HAL=${PLATFORM_HAL}
+    ${CPU_COMPILE_DEF}=1
+    $<$<BOOL:${ARM_MATH_DSP}>:ARM_MATH_DSP>
+    $<$<BOOL:${ARM_MATH_LOOPUNROLL}>:ARM_MATH_LOOPUNROLL>)
+
+# Link options:
+add_link_options(${CPU_LINK_OPT})
+set(CMAKE_ASM_FLAGS "${CPU_LINK_OPT}")
+
+# Warnings to be ignored:
+# L6314W = No section matches pattern
+# L6439W = Multiply defined Global Symbol
+add_link_options(
+    --diag_suppress=L6439W,L6314W
+    --info sizes,totals,unused,veneers
+    --strict
+    --callgraph
+    --load_addr_map_info
+    --xref
+    "$<$<CONFIG:RELEASE>:--no_debug>")
+
+# Function to add a map file output for the linker to dump diagnostic information to.
+function(add_target_map_file TARGET_NAME MAP_FILE_PATH)
+    target_link_options(${TARGET_NAME} PUBLIC
+        --map --symbols --list=${MAP_FILE_PATH})
+endfunction()
+
+# Function to add linker option to use the chosen linker script (scatter file).
+function(add_linker_script SCRIPT_DIR SCRIPT_NAME)
+    set(LINKER_SCRIPT_PATH ${SCRIPT_DIR}/${SCRIPT_NAME}.sct
+        CACHE STRING "Linker script path")
+    if (NOT EXISTS ${LINKER_SCRIPT_PATH})
+        message(FATAL_ERROR "Scatter file not found: ${LINKER_SCRIPT_PATH}")
+    endif()
+    message(STATUS "Using linker script: ${LINKER_SCRIPT_PATH}")
+    add_link_options(--scatter=${LINKER_SCRIPT_PATH})
+endfunction()
+
+# Function to set the command to copy/extract contents from an elf
+# into a binary file.
+function(add_bin_generation_command)
+
+    set(multiValueArgs SECTION_PATTERNS OUTPUT_BIN_NAMES)
+    set(oneValueArgs TARGET_NAME OUTPUT_DIR AXF_PATH)
+    cmake_parse_arguments(PARSED "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+    add_custom_command(TARGET ${PARSED_TARGET_NAME}
+        POST_BUILD
+        COMMAND fromelf --bin --output=${PARSED_OUTPUT_DIR}/
+        ${PARSED_AXF_PATH})
+
+endfunction()
+
+# Function to assert the compiler version
+function(enforce_compiler_version)
+    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS ${MIN_ARM_CLANG_VERSION})
+        message( FATAL_ERROR "Arm compiler version must be ${MIN_ARM_CLANG_VERSION} or greater to support ${CMAKE_SYSTEM_PROCESSOR} architecture." )
+    endif()
+endfunction()