arm64: dts: rockchip: Add rock5b overlays for PCIe endpoint mode

Add rock5b overlays for PCIe endpoint mode support.

If using the rock5b as an endpoint against a normal PC, only the
rk3588-rock-5b-pcie-ep.dtbo needs to be applied.

If using two rock5b:s, with one board as EP and the other board as RC,
rk3588-rock-5b-pcie-ep.dtbo and rk3588-rock-5b-pcie-srns.dtbo has to
be applied to the respective boards.
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Link: https://lore.kernel.org/r/20240607-rockchip-pcie-ep-v1-v5-13-0a042d6b0049@kernel.orgSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/Makefile

@@ -129,6 +129,8 @@ dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-ok3588-c.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-orangepi-5-plus.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-quartzpro64.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-rock-5b.dtb
+dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-rock-5b-pcie-ep.dtbo
+dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-rock-5b-pcie-srns.dtbo
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-tiger-haikou.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-toybrick-x0.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3588-turing-rk1.dtb

arch/arm64/boot/dts/rockchip/rk3588-rock-5b-pcie-ep.dtso

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * DT-overlay to run the PCIe3_4L Dual Mode controller in Endpoint mode
+ * in the SRNS (Separate Reference Clock No Spread) configuration.
+ *
+ * NOTE: If using a setup with two ROCK 5B:s, with one board running in
+ * RC mode and the other board running in EP mode, see also the device
+ * tree overlay: rk3588-rock-5b-pcie-srns.dtso.
+ */
+
+/dts-v1/;
+/plugin/;
+
+&pcie30phy {
+	rockchip,rx-common-refclk-mode = <0 0 0 0>;
+};
+
+&pcie3x4 {
+	status = "disabled";
+};
+
+&pcie3x4_ep {
+	vpcie3v3-supply = <&vcc3v3_pcie30>;
+	status = "okay";
+};

arch/arm64/boot/dts/rockchip/rk3588-rock-5b-pcie-srns.dtso

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * DT-overlay to run the PCIe3_4L Dual Mode controller in Root Complex
+ * mode in the SRNS (Separate Reference Clock No Spread) configuration.
+ *
+ * This device tree overlay is only needed (on the RC side) when running
+ * a setup with two ROCK 5B:s, with one board running in RC mode and the
+ * other board running in EP mode.
+ */
+
+/dts-v1/;
+/plugin/;
+
+&pcie30phy {
+	rockchip,rx-common-refclk-mode = <0 0 0 0>;
+};