1NVIDIA Tegra Boot and Power Management Processor (BPMP)
2
3The BPMP is a specific processor in Tegra chip, which is designed for
4booting process handling and offloading the power management, clock
5management, and reset control tasks from the CPU. The binding document
6defines the resources that would be used by the BPMP firmware driver,
7which can create the interprocessor communication (IPC) between the CPU
8and BPMP.
9
10Required properties:
11- compatible
12    Array of strings
13    One of:
14    - "nvidia,tegra186-bpmp"
15- mboxes : The phandle of mailbox controller and the mailbox specifier.
16- shmem : List of the phandle of the TX and RX shared memory area that
17	  the IPC between CPU and BPMP is based on.
18- #clock-cells : Should be 1.
19- #power-domain-cells : Should be 1.
20- #reset-cells : Should be 1.
21
22This node is a mailbox consumer. See the following files for details of
23the mailbox subsystem, and the specifiers implemented by the relevant
24provider(s):
25
26- .../mailbox/mailbox.txt
27- .../mailbox/nvidia,tegra186-hsp.txt
28
29This node is a clock, power domain, and reset provider. See the following
30files for general documentation of those features, and the specifiers
31implemented by this node:
32
33- .../clock/clock-bindings.txt
34- <dt-bindings/clock/tegra186-clock.h>
35- ../power/power-domain.yaml
36- <dt-bindings/power/tegra186-powergate.h>
37- .../reset/reset.txt
38- <dt-bindings/reset/tegra186-reset.h>
39
40The BPMP implements some services which must be represented by separate nodes.
41For example, it can provide access to certain I2C controllers, and the I2C
42bindings represent each I2C controller as a device tree node. Such nodes should
43be nested directly inside the main BPMP node.
44
45Software can determine whether a child node of the BPMP node represents a device
46by checking for a compatible property. Any node with a compatible property
47represents a device that can be instantiated. Nodes without a compatible
48property may be used to provide configuration information regarding the BPMP
49itself, although no such configuration nodes are currently defined by this
50binding.
51
52The BPMP firmware defines no single global name-/numbering-space for such
53services. Put another way, the numbering scheme for I2C buses is distinct from
54the numbering scheme for any other service the BPMP may provide (e.g. a future
55hypothetical SPI bus service). As such, child device nodes will have no reg
56property, and the BPMP node will have no #address-cells or #size-cells property.
57
58The shared memory bindings for BPMP
59-----------------------------------
60
61The shared memory area for the IPC TX and RX between CPU and BPMP are
62predefined and work on top of sysram, which is an SRAM inside the chip.
63
64See ".../sram/sram.txt" for the bindings.
65
66Example:
67
68hsp_top0: hsp@3c00000 {
69	...
70	#mbox-cells = <2>;
71};
72
73sysram@30000000 {
74	compatible = "nvidia,tegra186-sysram", "mmio-sram";
75	reg = <0x0 0x30000000 0x0 0x50000>;
76	#address-cells = <2>;
77	#size-cells = <2>;
78	ranges = <0 0x0 0x0 0x30000000 0x0 0x50000>;
79
80	cpu_bpmp_tx: shmem@4e000 {
81		compatible = "nvidia,tegra186-bpmp-shmem";
82		reg = <0x0 0x4e000 0x0 0x1000>;
83		label = "cpu-bpmp-tx";
84		pool;
85	};
86
87	cpu_bpmp_rx: shmem@4f000 {
88		compatible = "nvidia,tegra186-bpmp-shmem";
89		reg = <0x0 0x4f000 0x0 0x1000>;
90		label = "cpu-bpmp-rx";
91		pool;
92	};
93};
94
95bpmp {
96	compatible = "nvidia,tegra186-bpmp";
97	mboxes = <&hsp_top0 TEGRA_HSP_MBOX_TYPE_DB TEGRA_HSP_DB_MASTER_BPMP>;
98	shmem = <&cpu_bpmp_tx &cpu_bpmp_rx>;
99	#clock-cells = <1>;
100	#power-domain-cells = <1>;
101	#reset-cells = <1>;
102
103	i2c {
104		compatible = "...";
105		...
106	};
107};
108