linux: factor dts/dtc/dtb handling into a specific include

Fixes [BUGID #610]

The powerpc linux-yocto kernels were not creating dtb images
in the deploy directories. This was due to two problems:

  - the dtb generation rules were not being configured
  - the boards were not specifying a device tree in their config

This change addresses the first point by factoring out the
dtb generation routines into a new include that can be used by
multiple recipes.

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>

meta/recipes-kernel/linux/linux-dtb.inc

@@ -0,0 +1,27 @@
+# Support for device tree generation
+FILES_kernel_devicetree = "/boot/devicetree*"
+KERNEL_DEVICETREE_FLAGS = "-R 8 -p 0x3000"
+
+python __anonymous () {
+    import bb
+
+    devicetree = bb.data.getVar("KERNEL_DEVICETREE", d, 1) or ''
+    if devicetree:
+	depends = bb.data.getVar("DEPENDS", d, 1)
+	bb.data.setVar("DEPENDS", "%s dtc-native" % depends, d)
+	packages = bb.data.getVar("PACKAGES", d, 1)
+	bb.data.setVar("PACKAGES", "%s kernel-devicetree" % packages, d)
+}
+
+do_install_append() {
+    if test -n "${KERNEL_DEVICETREE}"; then
+	dtc -I dts -O dtb ${KERNEL_DEVICETREE_FLAGS} -o devicetree ${KERNEL_DEVICETREE}
+	install -m 0644 devicetree ${D}/boot/devicetree-${KERNEL_VERSION}
+	install -d ${DEPLOY_DIR_IMAGE}
+	install -m 0644 devicetree ${DEPLOY_DIR_IMAGE}/${KERNEL_IMAGE_BASE_NAME}.dtb
+	cd ${DEPLOY_DIR_IMAGE}
+	rm -f ${KERNEL_IMAGE_SYMLINK_NAME}.dtb
+	ln -sf ${KERNEL_IMAGE_BASE_NAME}.dtb ${KERNEL_IMAGE_SYMLINK_NAME}.dtb
+    fi
+}
+