Add the '-@' DTC option for the Raspberry Pi devices. This option populates the '__symbols__' node that contains all the necessary symbols for supporting device-tree overlays (for instance from the firmware or the bootloader) on these devices. The Rasbperry Pi devices are well known for their GPIO header, that allow various "HATs" or other modules do be connected and this enables users to create out-of-tree device-tree overlays for these modules. Please note that this change does increase the size of the resulting DTB by ~40%. For example, with v5.17 increase in size is as follows: bcm2711-rpi-400.dtb 26481 -> 36830 bytes bcm2711-rpi-4-b.dtb 26537 -> 36886 bytes bcm2711-rpi-cm4-io.dtb 26426 -> 36945 bytes bcm2837-rpi-3-a-plus.dtb 14133 -> 19740 bytes bcm2837-rpi-3-b.dtb 14310 -> 20006 bytes bcm2837-rpi-3-b-plus.dtb 14670 -> 20474 bytes bcm2837-rpi-cm3-io3.dtb 13680 -> 19266 bytes Signed-off-by: Aurelien Jarno <aurelien@xxxxxxxxxxx> --- arch/arm64/boot/dts/broadcom/Makefile | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm64/boot/dts/broadcom/Makefile b/arch/arm64/boot/dts/broadcom/Makefile index 5082fcd1fea5..0aa8ee2afdd5 100644 --- a/arch/arm64/boot/dts/broadcom/Makefile +++ b/arch/arm64/boot/dts/broadcom/Makefile @@ -1,4 +1,15 @@ # SPDX-License-Identifier: GPL-2.0 + +# Enables support for device-tree overlays +DTC_FLAGS_bcm2711-rpi-400 := -@ +DTC_FLAGS_bcm2711-rpi-4-b := -@ +DTC_FLAGS_bcm2711-rpi-cm4-io := -@ +DTC_FLAGS_bcm2837-rpi-3-a-plus := -@ +DTC_FLAGS_bcm2837-rpi-3-b := -@ +DTC_FLAGS_bcm2837-rpi-3-b-plus := -@ +DTC_FLAGS_bcm2837-rpi-cm3-io3 := -@ +DTC_FLAGS_bcm2837-rpi-zero-2-w := -@ + dtb-$(CONFIG_ARCH_BCM2835) += bcm2711-rpi-400.dtb \ bcm2711-rpi-4-b.dtb \ bcm2711-rpi-cm4-io.dtb \ -- 2.35.1
