From 884147c7d0b1b6571256feb11e12d893432625b2 Mon Sep 17 00:00:00 2001
From: Dima Zavin <dima@android.com>
Date: Fri, 16 Mar 2012 16:18:15 -0700
Subject: [PATCH] libc/kernel: Add rules to autogenerate device specific kernel
 headers

This change will automatically post-process kernel headers
specified by device, board, and product. This will allow us
to not check in each kernel header twice, at least for the
device specific headers for now.

Change-Id: I3bb144b6535504b7c26b807daa75de495554356d
Signed-off-by: Dima Zavin <dima@android.com>
---
 libc/kernel/Android.mk | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 libc/kernel/Android.mk

diff --git a/libc/kernel/Android.mk b/libc/kernel/Android.mk
new file mode 100644
index 000000000..6ad9dab90
--- /dev/null
+++ b/libc/kernel/Android.mk
@@ -0,0 +1,82 @@
+#
+# Copyright (C) 2012 The Android Open-Source Project
+#
+# 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.
+#
+
+#
+# This file does the bulk of the work to auto post-process kernel headers
+# provided by the device, board, and/or product.
+#
+# The build system exposes several variables for where to find the kernel
+# headers:
+#   TARGET_DEVICE_KERNEL_HEADERS is automatically created for the current
+#       device being built. It is set as $(TARGET_DEVICE_DIR)/kernel-headers,
+#       e.g. device/samsung/tuna/kernel-headers. This directory is not
+#       explicitly set by anyone, the build system always adds this subdir.
+#
+#   TARGET_BOARD_KERNEL_HEADERS is specified by the BoardConfig.mk file
+#       to allow other directories to be included. This is useful if there's
+#       some common place where a few headers are being kept for a group
+#       of devices. For example, device/<vendor>/common/kernel-headers could
+#       contain some headers for several of <vendor>'s devices.
+#
+#   TARGET_PRODUCT_KERNEL_HEADERS is generated by the product inheritance
+#       graph. This allows architecture products to provide headers for the
+#       devices using that architecture. For example,
+#       hardware/ti/omap4xxx/omap4.mk will specify
+#       PRODUCT_VENDOR_KERNEL_HEADERS variable that specify where the omap4
+#       specific headers are, e.g. hardware/ti/omap4xxx/kernel-headers.
+#       The build system then combines all the values specified by all the
+#       PRODUCT_VENDOR_KERNEL_HEADERS directives in the product inheritance
+#       tree and then exports a TARGET_PRODUCT_KERNEL_HEADERS variable.
+#
+# The directories specified in these three variables are scanned for header
+# files (files with .h suffix), processed with the clean_header.py script,
+# and dumped under TARGET_OUT_KERNEL_HEADERS
+# (typically $OUT/obj/kernel-headers). This subdirectory is then
+# automatically added to the include path.
+#
+# The files to be generated are added as a dependency to the
+# all_copied_headers rule to make sure that they are generated before
+# any C/C++ file that may need them.
+#
+#
+
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+_all_kernel_header_dirs := \
+	$(TARGET_DEVICE_KERNEL_HEADERS) \
+	$(TARGET_BOARD_KERNEL_HEADERS) \
+	$(TARGET_PRODUCT_KERNEL_HEADERS)
+
+define add-kernel-header-dir
+$(eval _headers := $(patsubst $(1)/%.h,%.h,$(shell find $(1)/ -type f -name '*.h')))
+$(eval GEN := $(addprefix $(TARGET_OUT_KERNEL_HEADERS)/,$(_headers)))
+$(GEN) : PRIVATE_PATH := $(LOCAL_PATH)
+$(GEN) : PRIVATE_MODULE := kernel-headers
+$(GEN) : PRIVATE_CUSTOM_TOOL = \
+					$$(LOCAL_PATH)/tools/clean_header.py \
+						-k $(1) -d $$(TARGET_OUT_KERNEL_HEADERS) $$< > $$@
+$(GEN) : $$(LOCAL_PATH)/tools/clean_header.py
+$(GEN) : $$(TARGET_OUT_KERNEL_HEADERS)/%.h : $(1)/%.h
+	$$(transform-generated-source)
+all_copied_headers: $(GEN)
+$(eval GEN :=)
+$(eval _headers :=)
+endef
+
+$(foreach d,$(_all_kernel_header_dirs),\
+    $(eval $(call add-kernel-header-dir,$(d))))
-- 
2.11.0