dt-bindings: phy: rockchip: Add Naneng combo PHY bindings

Add the compatible strings for the Naneng combo PHY found on rockchip SoC.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Yifeng Zhao <yifeng.zhao@rock-chips.com>
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20220208091326.12495-3-yifeng.zhao@rock-chips.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/phy-rockchip-naneng-combphy.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/phy-rockchip-naneng-combphy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Rockchip SoC Naneng Combo Phy Device Tree Bindings
+
+maintainers:
+  - Heiko Stuebner <heiko@sntech.de>
+
+properties:
+  compatible:
+    enum:
+      - rockchip,rk3568-naneng-combphy
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: reference clock
+      - description: apb clock
+      - description: pipe clock
+
+  clock-names:
+    items:
+      - const: ref
+      - const: apb
+      - const: pipe
+
+  resets:
+    items:
+      - description: exclusive PHY reset line
+
+  rockchip,enable-ssc:
+    type: boolean
+    description:
+      The option SSC can be enabled for U3, SATA and PCIE.
+      Most commercially available platforms use SSC to reduce EMI.
+
+  rockchip,ext-refclk:
+    type: boolean
+    description:
+      Many PCIe connections, especially backplane connections,
+      require a synchronous reference clock between the two link partners.
+      To achieve this a common clock source, referred to as REFCLK in
+      the PCI Express Card Electromechanical Specification,
+      should be used by both ends of the PCIe link.
+      In PCIe mode one can choose to use an internal or an external reference
+      clock.
+      By default the internal clock is selected. The PCIe PHY provides a 100MHz
+      differential clock output(optional with SSC) for system applications.
+      When selecting this option an externally 100MHz differential
+      reference clock needs to be provided to the PCIe PHY.
+
+  rockchip,pipe-grf:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Some additional phy settings are accessed through GRF regs.
+
+  rockchip,pipe-phy-grf:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Some additional pipe settings are accessed through GRF regs.
+
+  "#phy-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - resets
+  - rockchip,pipe-grf
+  - rockchip,pipe-phy-grf
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/rk3568-cru.h>
+
+    pipegrf: syscon@fdc50000 {
+      compatible = "rockchip,rk3568-pipe-grf", "syscon";
+      reg = <0xfdc50000 0x1000>;
+    };
+
+    pipe_phy_grf0: syscon@fdc70000 {
+      compatible = "rockchip,rk3568-pipe-phy-grf", "syscon";
+      reg = <0xfdc70000 0x1000>;
+    };
+
+    combphy0: phy@fe820000 {
+      compatible = "rockchip,rk3568-naneng-combphy";
+      reg = <0xfe820000 0x100>;
+      clocks = <&pmucru CLK_PCIEPHY0_REF>,
+               <&cru PCLK_PIPEPHY0>,
+               <&cru PCLK_PIPE>;
+      clock-names = "ref", "apb", "pipe";
+      assigned-clocks = <&pmucru CLK_PCIEPHY0_REF>;
+      assigned-clock-rates = <100000000>;
+      resets = <&cru SRST_PIPEPHY0>;
+      rockchip,pipe-grf = <&pipegrf>;
+      rockchip,pipe-phy-grf = <&pipe_phy_grf0>;
+      #phy-cells = <1>;
+    };