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+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"
+ - "nvidia,tegra194-hsp", "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"
+ - "sharedN", where 'N' is a number from zero up to the number of
+ external interrupts supported by the HSP instance minus one.
+ 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 cells. The first cell determines the HSP type and the second cell is used
+to identify the mailbox that the client is going to use.
+
+For doorbells, the second cell specifies the index of the doorbell to use.
+
+For shared mailboxes, the second cell is composed of two fields:
+- bits 31..24:
+ A bit mask of flags that further specify how the shared mailbox will be
+ used. Valid flags are:
+ - bit 31:
+ Defines the direction of the mailbox. If set, the mailbox will be used
+ as a producer (i.e. used to send data). If cleared, the mailbox is the
+ consumer of data sent by a producer.
+
+- bits 23.. 0:
+ The index of the shared mailbox to use. The number of available mailboxes
+ may vary by instance of the HSP block and SoC generation.
+
+The following file contains definitions that can be used to construct mailbox
+specifiers:
+
+ <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>;
+};