soong: Support prebuilt_kernel_headers

This depends on a kernel headers tarball path being passed in
TARGET_PREBUILT_KERNEL_HEADERS, in the style that the kleaf kernel
platform build generates.

Change-Id: Ib82659fa44ef221e73d0d129daafbaae6bad87a2

build/soong/Android.bp

@@ -42,6 +42,22 @@ lineage_generator {
     ],
 }
 
+lineage_generator {
+    name: "prebuilt_kernel_includes",
+
+    // The headers extract command
+    cmd: "mkdir -p $(KERNEL_BUILD_OUT_PREFIX)$(genDir) && gzip -d < $(TARGET_PREBUILT_KERNEL_HEADERS) | tar -x -C $(KERNEL_BUILD_OUT_PREFIX)$(genDir) && vendor/lineage/tools/clean_headers.sh $(KERNEL_BUILD_OUT_PREFIX)$(genDir)",
+
+    // Directories that can be imported by a cc_* module generated_headers property
+    export_include_dirs: [
+        "usr/audio/include/uapi",
+        "usr/include",
+        "usr/include/audio",
+        "usr/include/audio/include/uapi",
+        "usr/techpack/audio/include",
+    ],
+}
+
 bootstrap_go_package {
     name: "soong-lineage-mkdir",
     pkgPath: "lineage/soong/mkdir",
@@ -66,6 +82,14 @@ cc_defaults {
     recovery_available: true,
 }
 
+cc_defaults {
+    name: "prebuilt_kernel_header_defaults",
+    generated_headers: ["prebuilt_kernel_includes"],
+    export_generated_headers: ["prebuilt_kernel_includes"],
+    vendor_available: true,
+    recovery_available: true,
+}
+
 cc_library_headers {
     name: "generated_kernel_headers",
     defaults: ["generated_kernel_header_defaults"],
@@ -75,3 +99,8 @@ cc_library_headers {
     name: "qti_kernel_headers",
     defaults: ["generated_kernel_header_defaults"],
 }
+
+cc_library_headers {
+    name: "prebuilt_kernel_headers",
+    defaults: ["prebuilt_kernel_header_defaults"],
+}

config/BoardConfigSoong.mk

@@ -9,7 +9,8 @@ EXPORT_TO_SOONG := \
     KERNEL_MAKE_FLAGS \
     PATH_OVERRIDE_SOONG \
     TARGET_KERNEL_CONFIG \
-    TARGET_KERNEL_SOURCE
+    TARGET_KERNEL_SOURCE \
+    TARGET_PREBUILT_KERNEL_HEADERS
 
 # Setup SOONG_CONFIG_* vars to export the vars listed above.
 # Documentation here: