Add automatic generation of version and build type headers for compilation

This change replaces the static version and build type header file generation
by CMake with dynamic CMake targets to generate the version file whenever a Make
target is executed. Thus, there is no need anymore to reconfigure and rerun
CMake after the repository version or build configuration has changed.

1 files changed, 57 insertions, 0 deletions

diff --git a/cmake/Kernel.cmake b/cmake/Kernel.cmake
new file mode 100644
index 0000000..232c298
--- /dev/null
+++ b/cmake/Kernel.cmake
@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# CMake macros to build and install Linux kernel modules
+# Copyright (C) 2020 Manuel Bentele <development@manuel-bentele.de>
+#
+
+# macro to define kernel module targets
+macro(add_kernel_module MODULE_NAME KERNEL_BUILD_DIR KERNEL_INSTALL_DIR MODULE_MACRO MODULE_SOURCE_FILES MODULE_HEADER_FILES BUILD_SOURCE_FILE)
+    # create directory for kernel module
+    file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME})
+    # copy build source file
+    get_filename_component(BUILD_SOURCE_FILENAME ${BUILD_SOURCE_FILE} NAME)
+    add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${BUILD_SOURCE_FILENAME}
+                       COMMAND ${CMAKE_COMMAND} -E copy_if_different ${BUILD_SOURCE_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}
+                       DEPENDS ${BUILD_SOURCE_FILE})
+    set(BUILD_SOURCE_FILE_PREPARED ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${BUILD_SOURCE_FILENAME})
+    # copy source files
+    foreach(MODULE_SOURCE_FILE ${MODULE_SOURCE_FILES})
+        get_filename_component(MODULE_SOURCE_FILENAME ${MODULE_SOURCE_FILE} NAME)
+        add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_SOURCE_FILENAME}
+                           COMMAND ${CMAKE_COMMAND} -E copy_if_different ${MODULE_SOURCE_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}
+                           DEPENDS ${MODULE_SOURCE_FILE})
+        set(MODULE_SOURCE_FILES_PREPARED ${MODULE_SOURCE_FILES_PREPARED}
+                                         ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_SOURCE_FILENAME})
+    endforeach()
+    # copy header files
+    foreach(MODULE_HEADER_FILE ${MODULE_HEADER_FILES})
+        get_filename_component(MODULE_HEADER_FILENAME ${MODULE_HEADER_FILE} NAME)
+        add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_HEADER_FILENAME}
+                           COMMAND ${CMAKE_COMMAND} -E copy_if_different ${MODULE_HEADER_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}
+                           DEPENDS ${MODULE_HEADER_FILE})
+        set(MODULE_HEADER_FILES_PREPARED ${MODULE_HEADER_FILES_PREPARED}
+                                         ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_HEADER_FILENAME})
+    endforeach()
+    # check if module depends on another module
+    if(NOT ${ARGV7} STREQUAL "")
+        set(MODULE_EXTRA_SYMBOLS ${CMAKE_CURRENT_BINARY_DIR}/${ARGV7}/Module.symvers)
+    endif()
+    # define build command
+    set(MODULE_BUILD_COMMAND ${CMAKE_MAKE_PROGRAM} ${MODULE_MACRO}
+                                                   -C ${KERNEL_BUILD_DIR}
+                                                    M=${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME} modules
+                                                    EXTRA_CFLAGS=${KERNEL_C_FLAGS}
+                                                    KBUILD_EXTRA_SYMBOLS=${MODULE_EXTRA_SYMBOLS})
+    add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_NAME}.ko
+                       COMMAND ${MODULE_BUILD_COMMAND}
+                       WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}
+                       COMMENT "Build kernel module ${MODULE_NAME}"
+                       DEPENDS ${BUILD_SOURCE_FILE_PREPARED} ${MODULE_HEADER_FILES_PREPARED} ${MODULE_SOURCE_FILES_PREPARED}
+                       VERBATIM)
+    add_custom_target(${MODULE_NAME} ALL DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_NAME}.ko ${ARGV7})
+    # install kernel module
+    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_NAME}/${MODULE_NAME}.ko
+            DESTINATION ${KERNEL_INSTALL_DIR}
+            PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+            COMPONENT kernel)
+endmacro(add_kernel_module)