phy: Renesas R-Car Gen2 PHY driver

This PHY, though formally being a part of Renesas USBHS controller, contains the
UGCTRL2 register that controls multiplexing of the USB ports (Renesas calls them
channels) to the different USB controllers: channel 0 can be connected to either
PCI EHCI/OHCI or USBHS controllers, channel 2 can be connected to PCI EHCI/OHCI
or xHCI controllers.

This is a new driver for this USB PHY currently already supported under drivers/
usb/phy/. The reason for writing the new driver was the requirement that the
multiplexing  of USB channels to the controller be dynamic, depending on what
USB drivers  are loaded,  rather than static as provided by the old driver. The
infrastructure provided by drivers/phy/phy-core.c  seems to fit that purpose
ideally. The new driver only  supports device tree probing  for now.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/phy/rcar-gen2-phy.txt b/Documentation/devicetree/bindings/phy/rcar-gen2-phy.txt
new file mode 100644
index 000000000000..00fc52a034b7
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/rcar-gen2-phy.txt
@@ -0,0 +1,51 @@
+* Renesas R-Car generation 2 USB PHY
+
+This file provides information on what the device node for the R-Car generation
+2 USB PHY contains.
+
+Required properties:
+- compatible: "renesas,usb-phy-r8a7790" if the device is a part of R8A7790 SoC.
+	      "renesas,usb-phy-r8a7791" if the device is a part of R8A7791 SoC.
+- reg: offset and length of the register block.
+- #address-cells: number of address cells for the USB channel subnodes, must
+		  be <1>.
+- #size-cells: number of size cells for the USB channel subnodes, must be <0>.
+- clocks: clock phandle and specifier pair.
+- clock-names: string, clock input name, must be "usbhs".
+
+The USB PHY device tree node should have the subnodes corresponding to the USB
+channels. These subnodes must contain the following properties:
+- reg: the USB controller selector; see the table below for the values.
+- #phy-cells: see phy-bindings.txt in the same directory, must be <1>.
+
+The phandle's argument in the PHY specifier is the USB controller selector for
+the USB channel; see the selector meanings below:
+
++-----------+---------------+---------------+
+|\ Selector |               |               |
++ --------- +       0       |       1       |
+| Channel  \|               |               |
++-----------+---------------+---------------+
+| 0         | PCI EHCI/OHCI | HS-USB        |
+| 2         | PCI EHCI/OHCI | xHCI          |
++-----------+---------------+---------------+
+
+Example (Lager board):
+
+	usb-phy@e6590100 {
+		compatible = "renesas,usb-phy-r8a7790";
+		reg = <0 0xe6590100 0 0x100>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&mstp7_clks R8A7790_CLK_HSUSB>;
+		clock-names = "usbhs";
+
+		usb-channel@0 {
+			reg = <0>;
+			#phy-cells = <1>;
+		};
+		usb-channel@2 {
+			reg = <2>;
+			#phy-cells = <1>;
+		};
+	};