ARM: tegra: add BPMP DT bindings

The Tegra BPMP (Boot and Power Management Processor) is a separate
auxiliary CPU embedded into Tegra to perform power management work, and
controls related features such as clocks, resets, power domains, PMIC I2C
bus, etc. These bindings dictate how to represent the BPMP in device tree.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/doc/device-tree-bindings/firmware/nvidia,tegra186-bpmp.txt b/doc/device-tree-bindings/firmware/nvidia,tegra186-bpmp.txt
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+NVIDIA Tegra Boot and Power Management Processor (BPMP)
+
+The BPMP is a specific processor in Tegra chip, which is designed for
+booting process handling and offloading the power management, clock
+management, and reset control tasks from the CPU. The binding document
+defines the resources that would be used by the BPMP firmware driver,
+which can create the interprocessor communication (IPC) between the CPU
+and BPMP.
+
+Required properties:
+- name : Should be bpmp
+- compatible
+    Array of strings
+    One of:
+    - "nvidia,tegra186-bpmp"
+- mboxes : The phandle of mailbox controller and the mailbox specifier.
+- shmem : List of the phandle of the TX and RX shared memory area that
+	  the IPC between CPU and BPMP is based on.
+- #clock-cells : Should be 1.
+- #power-domain-cells : Should be 1.
+- #reset-cells : Should be 1.
+
+This node is a mailbox consumer. See the following files for details of
+the mailbox subsystem, and the specifiers implemented by the relevant
+provider(s):
+
+- .../mailbox/mailbox.txt
+- .../mailbox/nvidia,tegra186-hsp.txt
+
+This node is a clock, power domain, and reset provider. See the following
+files for general documentation of those features, and the specifiers
+implemented by this node:
+
+- .../clock/clock-bindings.txt
+- <dt-bindings/clock/tegra186-clock.h>
+- ../power/power_domain.txt
+- <dt-bindings/power/tegra186-powergate.h>
+- .../reset/reset.txt
+- <dt-bindings/reset/tegra186-reset.h>
+
+The shared memory bindings for BPMP
+-----------------------------------
+
+The shared memory area for the IPC TX and RX between CPU and BPMP are
+predefined and work on top of sysram, which is an SRAM inside the chip.
+
+See ".../sram/sram.txt" for the bindings.
+
+Example:
+
+hsp_top0: hsp@03c00000 {
+	...
+	#mbox-cells = <2>;
+};
+
+sysram@30000000 {
+	compatible = "nvidia,tegra186-sysram", "mmio-sram";
+	reg = <0x0 0x30000000 0x0 0x50000>;
+	#address-cells = <2>;
+	#size-cells = <2>;
+	ranges = <0 0x0 0x0 0x30000000 0x0 0x50000>;
+
+	cpu_bpmp_tx: bpmp_shmem@4e000 {
+		compatible = "nvidia,tegra186-bpmp-shmem";
+		reg = <0x0 0x4e000 0x0 0x1000>;
+	};
+
+	cpu_bpmp_rx: bpmp_shmem@4f000 {
+		compatible = "nvidia,tegra186-bpmp-shmem";
+		reg = <0x0 0x4f000 0x0 0x1000>;
+	};
+};
+
+bpmp {
+	compatible = "nvidia,tegra186-bpmp";
+	mboxes = <&hsp_top0 HSP_MBOX_TYPE_DB HSP_DB_MASTER_BPMP>;
+	shmem = <&cpu_bpmp_tx &cpu_bpmp_rx>;
+	#clock-cells = <1>;
+	#power-domain-cells = <1>;
+	#reset-cells = <1>;
+};