dt-bindings: arm: add DT binding for Marvell CP110 system controller

This commit adds the DT binding documentation for the Marvell CP110
system controller, which is part of the CP110 HW block, itself used in
the Marvell Armada 7K and 8K SoCs.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Rob Herring <rob@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Documentation/devicetree/bindings/arm/marvell/cp110-system-controller0.txt

+Marvell Armada CP110 System Controller 0
+========================================
+
+The CP110 is one of the two core HW blocks of the Marvell Armada 7K/8K
+SoCs. It contains two sets of system control registers, System
+Controller 0 and System Controller 1. This Device Tree binding allows
+to describe the first system controller, which provides registers to
+configure various aspects of the SoC.
+
+The Device Tree node representing this System Controller 0 provides a
+number of clocks:
+
+ - a set of core clocks
+ - a set of gatable clocks
+
+Those clocks can be referenced by other Device Tree nodes using two
+cells:
+ - The first cell must be 0 or 1. 0 for the core clocks and 1 for the
+   gatable clocks.
+ - The second cell identifies the particular core clock or gatable
+   clocks.
+
+The following clocks are available:
+ - Core clocks
+   - 0 0	APLL
+   - 0 1	PPv2 core
+   - 0 2	EIP
+   - 0 3	Core
+   - 0 4	NAND core
+ - Gatable clocks
+   - 1 0	Audio
+   - 1 1	Comm Unit
+   - 1 2	NAND
+   - 1 3	PPv2
+   - 1 4	SDIO
+   - 1 5	MG Domain
+   - 1 6	MG Core
+   - 1 7	XOR1
+   - 1 8	XOR0
+   - 1 9	GOP DP
+   - 1 11	PCIe x1 0
+   - 1 12	PCIe x1 1
+   - 1 13	PCIe x4
+   - 1 14	PCIe / XOR
+   - 1 15	SATA
+   - 1 16	SATA USB
+   - 1 17	Main
+   - 1 18	SD/MMC
+   - 1 21	Slow IO (SPI, NOR, BootROM, I2C, UART)
+   - 1 22	USB3H0
+   - 1 23	USB3H1
+   - 1 24	USB3 Device
+   - 1 25	EIP150
+   - 1 26	EIP197
+
+Required properties:
+
+ - compatible: must be:
+     "marvell,cp110-system-controller0", "syscon";
+ - reg: register area of the CP110 system controller 0
+ - #clock-cells: must be set to 2
+ - core-clock-output-names must be set to:
+	"cpm-apll", "cpm-ppv2-core", "cpm-eip", "cpm-core", "cpm-nand-core"
+ - gate-clock-output-names must be set to:
+	"cpm-audio", "cpm-communit", "cpm-nand", "cpm-ppv2", "cpm-sdio",
+	"cpm-mg-domain", "cpm-mg-core", "cpm-xor1", "cpm-xor0", "cpm-gop-dp", "none",
+	"cpm-pcie_x10", "cpm-pcie_x11", "cpm-pcie_x4", "cpm-pcie-xor", "cpm-sata",
+	"cpm-sata-usb", "cpm-main", "cpm-sd-mmc", "none", "none", "cpm-slow-io",
+	"cpm-usb3h0", "cpm-usb3h1", "cpm-usb3dev", "cpm-eip150", "cpm-eip197";
+
+Example:
+
+	cpm_syscon0: system-controller@440000 {
+		compatible = "marvell,cp110-system-controller0", "syscon";
+		reg = <0x440000 0x1000>;
+		#clock-cells = <2>;
+		core-clock-output-names = "cpm-apll", "cpm-ppv2-core", "cpm-eip", "cpm-core", "cpm-nand-core";
+		gate-clock-output-names = "cpm-audio", "cpm-communit", "cpm-nand", "cpm-ppv2", "cpm-sdio",
+			"cpm-mg-domain", "cpm-mg-core", "cpm-xor1", "cpm-xor0", "cpm-gop-dp", "none",
+			"cpm-pcie_x10", "cpm-pcie_x11", "cpm-pcie_x4", "cpm-pcie-xor", "cpm-sata",
+			"cpm-sata-usb", "cpm-main", "cpm-sd-mmc", "none", "none", "cpm-slow-io",
+			"cpm-usb3h0", "cpm-usb3h1", "cpm-usb3dev", "cpm-eip150", "cpm-eip197";
+	};