crypto: Add mbedtls-psa as a submodule

mbedtls-psa contains an implementation of libmbedcrypto, including the PSA
Crypto API.
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index da1eb64..cab8c27 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -140,48 +140,80 @@
 endif()
 
 if(USE_STATIC_MBEDTLS_LIBRARY)
-    add_library(${mbedcrypto_static_target} STATIC ${src_crypto})
-    set_target_properties(${mbedcrypto_static_target} PROPERTIES OUTPUT_NAME mbedcrypto)
-    target_link_libraries(${mbedcrypto_static_target} ${libs})
-    target_include_directories(${mbedcrypto_static_target} PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    if(NOT USE_CRYPTO_SUBMODULE)
+        add_library(${mbedcrypto_static_target} STATIC ${src_crypto})
+        set_target_properties(${mbedcrypto_static_target} PROPERTIES OUTPUT_NAME mbedcrypto)
+        target_link_libraries(${mbedcrypto_static_target} ${libs})
+        target_include_directories(${mbedcrypto_static_target} PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    endif()
 
     add_library(${mbedx509_static_target} STATIC ${src_x509})
     set_target_properties(${mbedx509_static_target} PROPERTIES OUTPUT_NAME mbedx509)
     target_link_libraries(${mbedx509_static_target} ${libs} ${mbedcrypto_static_target})
-    target_include_directories(${mbedx509_static_target} PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    target_include_directories(${mbedx509_static_target}
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
     add_library(${mbedtls_static_target} STATIC ${src_tls})
     set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
     target_link_libraries(${mbedtls_static_target} ${libs} ${mbedx509_static_target})
-    target_include_directories(${mbedtls_static_target} PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    target_include_directories(${mbedtls_static_target}
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/
+        )
 
-    install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_STATIC_MBEDTLS_LIBRARY)
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
-    add_library(mbedcrypto SHARED ${src_crypto})
-    set_target_properties(mbedcrypto PROPERTIES VERSION 2.14.0 SOVERSION 3)
-    target_link_libraries(mbedcrypto ${libs})
-    target_include_directories(mbedcrypto PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    if(NOT USE_CRYPTO_SUBMODULE)
+        add_library(mbedcrypto SHARED ${src_crypto})
+        set_target_properties(mbedcrypto PROPERTIES VERSION 2.14.0 SOVERSION 3)
+        target_link_libraries(mbedcrypto ${libs})
+        target_include_directories(mbedcrypto PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    endif()
 
     add_library(mbedx509 SHARED ${src_x509})
     set_target_properties(mbedx509 PROPERTIES VERSION 2.14.0 SOVERSION 0)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
-    target_include_directories(mbedx509 PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    target_include_directories(mbedx509
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
     add_library(mbedtls SHARED ${src_tls})
     set_target_properties(mbedtls PROPERTIES VERSION 2.14.0 SOVERSION 12)
     target_link_libraries(mbedtls ${libs} mbedx509)
-    target_include_directories(mbedtls PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    target_include_directories(mbedtls
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
-    install(TARGETS mbedtls mbedx509 mbedcrypto
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS mbedtls mbedx509
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        install(TARGETS mbedtls mbedx509 mbedcrypto
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_SHARED_MBEDTLS_LIBRARY)
 
-add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
-if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
-    add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+if(USE_CRYPTO_SUBMODULE)
+    add_custom_target(lib DEPENDS mbedx509 mbedtls)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(lib mbedx509_static mbedtls_static)
+    endif()
+else()
+    add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+    endif()
 endif()