dt-bindings: mailbox: Add Tegra HSP binding

NVIDIA Tegra Hardware Synchronization Primitives (HSP)

The HSP modules are used for the processors to share resources and communicate

together. It provides a set of hardware synchronization primitives for

interprocessor communication. So the interprocessor communication (IPC)

protocols can use hardware synchronization primitives, when operating between

two processors not in an SMP relationship.

The features that HSP supported are shared mailboxes, shared semaphores,

arbitrated semaphores and doorbells.

Required properties:

- name : Should be hsp

- compatible

    Array of strings.

    one of:

    - "nvidia,tegra186-hsp"

- reg : Offset and length of the register set for the device.

- interrupt-names

    Array of strings.

    Contains a list of names for the interrupts described by the interrupt

    property. May contain the following entries, in any order:

    - "doorbell"

    Users of this binding MUST look up entries in the interrupt property

    by name, using this interrupt-names property to do so.

- interrupts

    Array of interrupt specifiers.

    Must contain one entry per entry in the interrupt-names property,

    in a matching order.

- #mbox-cells : Should be 2.

The mbox specifier of the "mboxes" property in the client node should

contain two data. The first one should be the HSP type and the second

one should be the ID that the client is going to use. Those information

can be found in the following file.

- <dt-bindings/mailbox/tegra186-hsp.h>.

Example:

hsp_top0: hsp@3c00000 {

	compatible = "nvidia,tegra186-hsp";

	reg = <0x0 0x03c00000 0x0 0xa0000>;

	interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>;

	interrupt-names = "doorbell";

	#mbox-cells = <2>;

};

client {

	...

	mboxes = <&hsp_top0 TEGRA_HSP_MBOX_TYPE_DB TEGRA_HSP_DB_MASTER_XXX>;

};

/*

 * This header provides constants for binding nvidia,tegra186-hsp.

 */

#ifndef _DT_BINDINGS_MAILBOX_TEGRA186_HSP_H

#define _DT_BINDINGS_MAILBOX_TEGRA186_HSP_H

/*

 * These define the type of mailbox that is to be used (doorbell, shared

 * mailbox, shared semaphore or arbitrated semaphore).

 */

#define TEGRA_HSP_MBOX_TYPE_DB 0x0

#define TEGRA_HSP_MBOX_TYPE_SM 0x1

#define TEGRA_HSP_MBOX_TYPE_SS 0x2

#define TEGRA_HSP_MBOX_TYPE_AS 0x3

/*

 * These defines represent the bit associated with the given master ID in the

 * doorbell registers.

 */

#define TEGRA_HSP_DB_MASTER_CCPLEX 17

#define TEGRA_HSP_DB_MASTER_BPMP 19

#endif