AndroidKernel.mk: Add support for multi kernel tree

We now support building Android in a build tree that contains
multiple kernels. The kernel version to be built is passed in
by the higher level makefiles.

Currently supported structure:
- legacy <Android Root>/kernel
- New <Android Root>/kernel/msm-*

Change-Id: Ibd6c03c019643adfbadc61e46a3dd760930028bb
Signed-off-by: Ameya Thakur <ameyat@codeaurora.org>
Signed-off-by: David Ng <dave@codeaurora.org>

1 files changed, 41 insertions, 15 deletions

diff --git a/AndroidKernel.mk b/AndroidKernel.mk
index 09ef02bb2e47..4914401f3fda 100644
--- a/AndroidKernel.mk
+++ b/AndroidKernel.mk
@@ -47,7 +47,27 @@ ifeq ($(strip $(KERNEL_GCC_NOANDROID_CHK)),0)
 KERNEL_CFLAGS := KCFLAGS=-mno-android
 endif
 
-KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
+mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
+current_dir := $(notdir $(patsubst %/,%,$(dir $(mkfile_path))))
+ifeq ($(TARGET_KERNEL_VERSION),)
+    TARGET_KERNEL_VERSION := 3.18
+endif
+TARGET_KERNEL := msm-$(TARGET_KERNEL_VERSION)
+ifeq ($(TARGET_KERNEL),$(current_dir))
+    # New style, kernel/msm-version
+    BUILD_ROOT_LOC := ../../
+    TARGET_KERNEL_SOURCE := kernel/$(TARGET_KERNEL)
+    KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/kernel/$(TARGET_KERNEL)
+    KERNEL_SYMLINK := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
+    KERNEL_USR := $(KERNEL_SYMLINK)/usr
+else
+    # Legacy style, kernel source directly under kernel
+    KERNEL_LEGACY_DIR := true
+    BUILD_ROOT_LOC := ../
+    TARGET_KERNEL_SOURCE := kernel
+    KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
+endif
+
 KERNEL_CONFIG := $(KERNEL_OUT)/.config
 
 ifeq ($(KERNEL_DEFCONFIG)$(wildcard $(KERNEL_CONFIG)),)
@@ -92,47 +112,53 @@ mpath=`dirname $$mdpath`; rm -rf $$mpath;\
 fi
 endef
 
+ifneq ($(KERNEL_LEGACY_DIR),true)
+$(KERNEL_USR): $(TARGET_PREBUILT_INT_KERNEL)
+	rm -rf $(KERNEL_SYMLINK)
+	ln -s kernel/$(TARGET_KERNEL) $(KERNEL_SYMLINK)
+endif
+
 $(KERNEL_OUT):
 	mkdir -p $(KERNEL_OUT)
 
 $(KERNEL_CONFIG): $(KERNEL_OUT)
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG)
+	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG)
 	$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
 			echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
 			echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
-			$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fi
+			$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fi
 
 $(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_OUT) $(KERNEL_HEADERS_INSTALL)
 	$(hide) echo "Building kernel..."
 	$(hide) rm -rf $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/dts
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS)
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS) modules
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) INSTALL_MOD_PATH=../../$(KERNEL_MODULES_INSTALL) INSTALL_MOD_STRIP=1 ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) modules_install
+	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS)
+	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_CFLAGS) modules
+	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) INSTALL_MOD_PATH=../../$(KERNEL_MODULES_INSTALL) INSTALL_MOD_STRIP=1 ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) modules_install
 	$(mv-modules)
 	$(clean-module-folder)
 
 $(KERNEL_HEADERS_INSTALL): $(KERNEL_OUT)
 	$(hide) if [ ! -z "$(KERNEL_HEADER_DEFCONFIG)" ]; then \
-			$(hide) rm -f ../$(KERNEL_CONFIG); \
-			$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_HEADER_DEFCONFIG); \
-			$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) headers_install; fi
+			$(hide) rm -f $(BUILD_ROOT_LOC)$(KERNEL_CONFIG); \
+			$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_HEADER_DEFCONFIG); \
+			$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) headers_install; fi
 	$(hide) if [ "$(KERNEL_HEADER_DEFCONFIG)" != "$(KERNEL_DEFCONFIG)" ]; then \
 			echo "Used a different defconfig for header generation"; \
-			$(hide) rm -f ../$(KERNEL_CONFIG); \
-			$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG); fi
+			$(hide) rm -f $(BUILD_ROOT_LOC)$(KERNEL_CONFIG); \
+			$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG); fi
 	$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
 			echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
 			echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
-			$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fi
+			$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) oldconfig; fi
 
 kerneltags: $(KERNEL_OUT) $(KERNEL_CONFIG)
-	$(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) tags
+	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) tags
 
 kernelconfig: $(KERNEL_OUT) $(KERNEL_CONFIG)
 	env KCONFIG_NOTIMESTAMP=true \
-	     $(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) menuconfig
+	     $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) menuconfig
 	env KCONFIG_NOTIMESTAMP=true \
-	     $(MAKE) -C kernel O=../$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) savedefconfig
+	     $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(BUILD_ROOT_LOC)$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) savedefconfig
 	cp $(KERNEL_OUT)/defconfig kernel/arch/$(KERNEL_ARCH)/configs/$(KERNEL_DEFCONFIG)
 
 endif