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+Rockchip EMMC PHY
+-----------------------
+
+Required properties:
+ - compatible: rockchip,rk3399-emmc-phy
+ - #phy-cells: must be 0
+ - reg: PHY register address offset and length in "general
+ register files"
+
+Optional properties:
+ - clock-names: Should contain "emmcclk". Although this is listed as optional
+ (because most boards can get basic functionality without having
+ access to it), it is strongly suggested.
+ See ../clock/clock-bindings.txt for details.
+ - clocks: Should have a phandle to the card clock exported by the SDHCI driver.
+ - drive-impedance-ohm: Specifies the drive impedance in Ohm.
+ Possible values are 33, 40, 50, 66 and 100.
+ If not set, the default value of 50 will be applied.
+
+Example:
+
+
+grf: syscon@ff770000 {
+ compatible = "rockchip,rk3399-grf", "syscon", "simple-mfd";
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+...
+
+ emmcphy: phy@f780 {
+ compatible = "rockchip,rk3399-emmc-phy";
+ reg = <0xf780 0x20>;
+ clocks = <&sdhci>;
+ clock-names = "emmcclk";
+ drive-impedance-ohm = <50>;
+ #phy-cells = <0>;
+ };
+};