* Nuvoton FLASH Interface Unit (FIU) SPI Controller

NPCM FIU supports single, dual and quad communication interface.

The NPCM7XX supports three FIU modules,
FIU0 and FIUx supports two chip selects,
FIU3 support four chip select.

The NPCM8XX supports four FIU modules,
FIU0 and FIUx supports two chip selects,
FIU1 and FIU3 supports four chip selects.

Required properties:
  - compatible : "nuvoton,npcm750-fiu" for Poleg NPCM7XX BMC
			     "nuvoton,npcm845-fiu" for Arbel NPCM8XX BMC
  - #address-cells : should be 1.
  - #size-cells : should be 0.
  - reg : the first contains the register location and length,
          the second contains the memory mapping address and length
  - reg-names: Should contain the reg names "control" and "memory"
  - clocks : phandle of FIU reference clock.

Required properties in case the pins can be muxed:
  - pinctrl-names : a pinctrl state named "default" must be defined.
  - pinctrl-0 : phandle referencing pin configuration of the device.

Optional property:
  - nuvoton,spix-mode: enable spix-mode for an expansion bus to an ASIC or CPLD.

Aliases:
- All the FIU controller nodes should be represented in the aliases node using
  the following format 'fiu{n}' where n is a unique number for the alias.
  In the NPCM7XX BMC:
  		fiu0 represent fiu 0 controller
  		fiu1 represent fiu 3 controller
  		fiu2 represent fiu x controller

  In the NPCM8XX BMC:
  		fiu0 represent fiu 0 controller
  		fiu1 represent fiu 1 controller
  		fiu2 represent fiu 3 controller
  		fiu3 represent fiu x controller

Example:
fiu3: spi@c00000000 {
	compatible = "nuvoton,npcm750-fiu";
	#address-cells = <1>;
	#size-cells = <0>;
	reg = <0xfb000000 0x1000>, <0x80000000 0x10000000>;
	reg-names = "control", "memory";
	clocks = <&clk NPCM7XX_CLK_AHB>;
	pinctrl-names = "default";
	pinctrl-0 = <&spi3_pins>;
	spi-nor@0 {
			...
	};
};