dt-bindings: firmware: Add bindings for Tegra210 BPMP

NVIDIA Tegra210 Boot and Power Management Processor (BPMP)

The Boot and Power Management Processor (BPMP) is a co-processor found

in Tegra210 SoC. It is designed to handle the early stages of the boot

process as well as to assisting in entering deep low power state

(suspend to ram), and also offloading DRAM memory clock scaling on

some platforms. The binding document defines the resources that would

be used by the BPMP T210 firmware driver, which can create the

interprocessor communication (IPC) between the CPU and BPMP.

Required properties:

- compatible

    Array of strings

    One of:

    - "nvidia,tegra210-bpmp"

- reg: physical base address and length for HW synchornization primitives

       1) base address and length to Tegra 'atomics' hardware

       2) base address and length to Tegra 'semaphore' hardware

- interrupts: specifies the interrupt number for receiving messages ("rx")

              and for triggering messages ("tx")

Optional properties:

- #clock-cells : Should be 1 for platforms where DRAM clock control is

                 offloaded to bpmp.

Example:

bpmp@70016000 {

	compatible = "nvidia,tegra210-bpmp";

	reg = <0x0 0x70016000 0x0 0x2000

	       0x0 0x60001000 0x0 0x1000>;

	interrupts = <GIC_SPI 6 IRQ_TYPE_EDGE_RISING>,

		     <GIC_SPI 4 IRQ_TYPE_EDGE_RISING>;

	interrupt-names = "tx", "rx";

};