Documentation: binding: Modify the exynos5440 PCIe binding

According to using PHY framework, updates the exynos5440-pcie binding.  For
maintaining backward compatibility, leaves the current dt-binding.  (It
should be deprecated.)

Recommends to use the PHY Framework and "config" property to follow the
designware-pcie binding.  If you use the old way, can see "missing *config*
reg space" message.  Because the getting configuration space address from
range is old way.

NOTE: When use the "config" property, first name of 'reg-names' must be set
to "elbi".  Otherwise driver can't maintain the backward capability.
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/pci/samsung,exynos5440-pcie.txt

@@ -7,8 +7,19 @@ Required properties:
 - compatible: "samsung,exynos5440-pcie"
 - reg: base addresses and lengths of the pcie controller,
 	the phy controller, additional register for the phy controller.
+	(Registers for the phy controller are DEPRECATED.
+	 Use the PHY framework.)
+- reg-names : First name should be set to "elbi".
+	And use the "config" instead of getting the confgiruation address space
+	from "ranges".
+	NOTE: When use the "config" property, reg-names must be set.
 - interrupts: A list of interrupt outputs for level interrupt,
 	pulse interrupt, special interrupt.
+- phys: From PHY binding. Phandle for the Generic PHY.
+	Refer to Documentation/devicetree/bindings/phy/samsung-phy.txt
+
+Other common properties refer to
+	Documentation/devicetree/binding/pci/designware-pcie.txt
 
 Example:
 
@@ -54,6 +65,24 @@ SoC specific DT Entry:
 		num-lanes = <4>;
 	};
 
+With using PHY framework:
+	pcie_phy0: pcie-phy@270000 {
+		...
+		reg = <0x270000 0x1000>, <0x271000 0x40>;
+		reg-names = "phy", "block";
+		...
+	};
+
+	pcie@290000 {
+		...
+		reg = <0x290000 0x1000>, <0x40000000 0x1000>;
+		reg-names = "elbi", "config";
+		phys = <&pcie_phy0>;
+		ranges = <0x81000000 0 0	  0x60001000 0 0x00010000
+			  0x82000000 0 0x60011000 0x60011000 0 0x1ffef000>;
+		...
+	};
+
 Board specific DT Entry:
 
 	pcie@290000 {