Atmel system registers

Chipid required properties:
- compatible: Should be "atmel,sama5d2-chipid"
- reg : Should contain registers location and length

PIT Timer required properties:
- compatible: Should be "atmel,at91sam9260-pit"
- reg: Should contain registers location and length
- interrupts: Should contain interrupt for the PIT which is the IRQ line
  shared across all System Controller members.

System Timer (ST) required properties:
- compatible: Should be "atmel,at91rm9200-st", "syscon", "simple-mfd"
- reg: Should contain registers location and length
- interrupts: Should contain interrupt for the ST which is the IRQ line
  shared across all System Controller members.
- clocks: phandle to input clock.
Its subnodes can be:
- watchdog: compatible should be "atmel,at91rm9200-wdt"

RSTC Reset Controller required properties:
- compatible: Should be "atmel,<chip>-rstc".
  <chip> can be "at91sam9260", "at91sam9g45", "sama5d3" or "samx7"
  it also can be "microchip,sam9x60-rstc"
- reg: Should contain registers location and length
- clocks: phandle to input clock.

Example:

	rstc@fffffd00 {
		compatible = "atmel,at91sam9260-rstc";
		reg = <0xfffffd00 0x10>;
		clocks = <&clk32k>;
	};

RAMC SDRAM/DDR Controller required properties:
- compatible: Should be "atmel,at91rm9200-sdramc", "syscon"
			"atmel,at91sam9260-sdramc",
			"atmel,at91sam9g45-ddramc",
			"atmel,sama5d3-ddramc",
- reg: Should contain registers location and length

Examples:

	ramc0: ramc@ffffe800 {
		compatible = "atmel,at91sam9g45-ddramc";
		reg = <0xffffe800 0x200>;
	};

SHDWC Shutdown Controller

required properties:
- compatible: Should be "atmel,<chip>-shdwc".
  <chip> can be "at91sam9260", "at91sam9rl" or "at91sam9x5".
- reg: Should contain registers location and length
- clocks: phandle to input clock.

optional properties:
- atmel,wakeup-mode: String, operation mode of the wakeup mode.
  Supported values are: "none", "high", "low", "any".
- atmel,wakeup-counter: Counter on Wake-up 0 (between 0x0 and 0xf).

optional at91sam9260 properties:
- atmel,wakeup-rtt-timer: boolean to enable Real-time Timer Wake-up.

optional at91sam9rl properties:
- atmel,wakeup-rtc-timer: boolean to enable Real-time Clock Wake-up.
- atmel,wakeup-rtt-timer: boolean to enable Real-time Timer Wake-up.

optional at91sam9x5 properties:
- atmel,wakeup-rtc-timer: boolean to enable Real-time Clock Wake-up.

Example:

	shdwc@fffffd10 {
		compatible = "atmel,at91sam9260-shdwc";
		reg = <0xfffffd10 0x10>;
		clocks = <&clk32k>;
	};

SHDWC SAMA5D2-Compatible Shutdown Controller

1) shdwc node

required properties:
- compatible: should be "atmel,sama5d2-shdwc".
- reg: should contain registers location and length
- clocks: phandle to input clock.
- #address-cells: should be one. The cell is the wake-up input index.
- #size-cells: should be zero.

optional properties:

- debounce-delay-us: minimum wake-up inputs debouncer period in
  microseconds. It's usually a board-related property.
- atmel,wakeup-rtc-timer: boolean to enable Real-Time Clock wake-up.

The node contains child nodes for each wake-up input that the platform uses.

2) input nodes

Wake-up input nodes are usually described in the "board" part of the Device
Tree. Note also that input 0 is linked to the wake-up pin and is frequently
used.

Required properties:
- reg: should contain the wake-up input index [0 - 15].

Optional properties:
- atmel,wakeup-active-high: boolean, the corresponding wake-up input described
  by the child, forces the wake-up of the core power supply on a high level.
  The default is to be active low.

Example:

On the SoC side:
	shdwc@f8048010 {
		compatible = "atmel,sama5d2-shdwc";
		reg = <0xf8048010 0x10>;
		clocks = <&clk32k>;
		#address-cells = <1>;
		#size-cells = <0>;
		atmel,wakeup-rtc-timer;
	};

On the board side:
	shdwc@f8048010 {
		debounce-delay-us = <976>;

		input@0 {
			reg = <0>;
		};

		input@1 {
			reg = <1>;
			atmel,wakeup-active-high;
		};
	};

Special Function Registers (SFR)

Special Function Registers (SFR) manage specific aspects of the integrated
memory, bridge implementations, processor and other functionality not controlled
elsewhere.

required properties:
- compatible: Should be "atmel,<chip>-sfr", "syscon" or
	"atmel,<chip>-sfrbu", "syscon"
  <chip> can be "sama5d3", "sama5d4" or "sama5d2".
  It also can be "microchip,sam9x60-sfr", "syscon".
- reg: Should contain registers location and length

	sfr@f0038000 {
		compatible = "atmel,sama5d3-sfr", "syscon";
		reg = <0xf0038000 0x60>;
	};

Security Module (SECUMOD)

The Security Module macrocell provides all necessary secure functions to avoid
voltage, temperature, frequency and mechanical attacks on the chip. It also
embeds secure memories that can be scrambled.

The Security Module also offers the PIOBU pins which can be used as GPIO pins.
Note that they maintain their voltage during Backup/Self-refresh.

required properties:
- compatible: Should be "atmel,<chip>-secumod", "syscon".
  <chip> can be "sama5d2".
- reg: Should contain registers location and length
- gpio-controller:	Marks the port as GPIO controller.
- #gpio-cells:		There are 2. The pin number is the
			first, the second represents additional
			parameters such as GPIO_ACTIVE_HIGH/LOW.


	secumod@fc040000 {
		compatible = "atmel,sama5d2-secumod", "syscon";
		reg = <0xfc040000 0x100>;
		gpio-controller;
		#gpio-cells = <2>;
	};
