brcm2708: add support for device tree overlays

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

SVN-Revision: 47125

target/linux/brcm2708/image/Makefile

@@ -21,6 +21,12 @@ else
   endef
 endif
 
+define Image/Prepare
+	rm -rf $(KDIR)/overlays
+	mkdir -p $(KDIR)/overlays
+	$(CP) $(DTS_DIR)/overlays/*.dtb $(KDIR)/overlays/
+endef
+
 ### Image scripts ###
 define Build/gen-cfg
 	cat config.txt > $@.config
@@ -41,6 +47,7 @@ define Build/boot-img
 	mcopy -i $@.boot $@.config ::config.txt
 	mcopy -i $@.boot $(word 1,$^) ::kernel.img
 	mcopy -i $@.boot $(DTS_DIR)/$(DEVICE_DTS).dtb ::$(DEVICE_DTS).dtb
+	mcopy -s -i $@.boot $(KDIR)/overlays ::
 endef
 
 define Build/sdcard-img

target/linux/brcm2708/image/config.txt

@@ -927,3 +927,12 @@ init_uart_clock=3000000
 ################################################################################
 
 dtparam=random=on,watchdog=on,audio=on,i2c0=on,i2c1=on,spi=on
+
+#dtoverlay=hifiberry-amp-overlay
+#dtoverlay=hifiberry-dac-overlay
+#dtoverlay=hifiberry-dacplus-overlay
+#dtoverlay=hifiberry-digi-overlay
+#dtoverlay=iqaudio-dac-overlay
+#dtoverlay=iqaudio-dacplus-overlay
+#dtoverlay=raspidac3-overlay
+#dtoverlay=rpi-proto-overlay