[deliverable/linux.git] / Documentation / devicetree / bindings / arm / arm,scpi.txt

System Control and Power Interface (SCPI) Message Protocol
----------------------------------------------------------

Firmware implementing the SCPI described in ARM document number ARM DUI 0922B
("ARM Compute Subsystem SCP: Message Interface Protocols")[0] can be used
by Linux to initiate various system control and power operations.

Required properties:

- compatible : should be "arm,scpi"
- mboxes: List of phandle and mailbox channel specifiers
	  All the channels reserved by remote SCP firmware for use by
	  SCPI message protocol should be specified in any order
- shmem : List of phandle pointing to the shared memory(SHM) area between the
	  processors using these mailboxes for IPC, one for each mailbox
	  SHM can be any memory reserved for the purpose of this communication
	  between the processors.

See Documentation/devicetree/bindings/mailbox/mailbox.txt
for more details about the generic mailbox controller and
client driver bindings.

Clock bindings for the clocks based on SCPI Message Protocol
------------------------------------------------------------

This binding uses the common clock binding[1].

Container Node
==============
Required properties:
- compatible : should be "arm,scpi-clocks"
	       All the clocks provided by SCP firmware via SCPI message
	       protocol much be listed as sub-nodes under this node.

Sub-nodes
=========
Required properties:
- compatible : shall include one of the following
	"arm,scpi-dvfs-clocks" - all the clocks that are variable and index based.
		These clocks don't provide an entire range of values between the
		limits but only discrete points within the range. The firmware
		provides the mapping for each such operating frequency and the
		index associated with it. The firmware also manages the
		voltage scaling appropriately with the clock scaling.
	"arm,scpi-variable-clocks" - all the clocks that are variable and provide full
		range within the specified range. The firmware provides the
		range of values within a specified range.

Other required properties for all clocks(all from common clock binding):
- #clock-cells : Should be 1. Contains the Clock ID value used by SCPI commands.
- clock-output-names : shall be the corresponding names of the outputs.
- clock-indices: The identifying number for the clocks(i.e.clock_id) in the
	node. It can be non linear and hence provide the mapping of identifiers
	into the clock-output-names array.

SRAM and Shared Memory for SCPI
-------------------------------

A small area of SRAM is reserved for SCPI communication between application
processors and SCP.

Required properties:
- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno

The rest of the properties should follow the generic mmio-sram description
found in ../../sram/sram.txt

Each sub-node represents the reserved area for SCPI.

Required sub-node properties:
- reg : The base offset and size of the reserved area with the SRAM
- compatible : should be "arm,juno-scp-shmem" for Non-secure SRAM based
	       shared memory on Juno platforms

Sensor bindings for the sensors based on SCPI Message Protocol
--------------------------------------------------------------
SCPI provides an API to access the various sensors on the SoC.

Required properties:
- compatible : should be "arm,scpi-sensors".
- #thermal-sensor-cells: should be set to 1. This property follows the
			 thermal device tree bindings[2].

			 Valid cell values are raw identifiers (Sensor
			 ID) as used by the firmware. Refer to
			 platform documentation for your
			 implementation for the IDs to use. For Juno
			 R0 and Juno R1 refer to [3].

[0] http://infocenter.arm.com/help/topic/com.arm.doc.dui0922b/index.html
[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
[2] Documentation/devicetree/bindings/thermal/thermal.txt
[3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/apas03s22.html

Example:

sram: sram@50000000 {
	compatible = "arm,juno-sram-ns", "mmio-sram";
	reg = <0x0 0x50000000 0x0 0x10000>;

	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0 0x0 0x50000000 0x10000>;

	cpu_scp_lpri: scp-shmem@0 {
		compatible = "arm,juno-scp-shmem";
		reg = <0x0 0x200>;
	};

	cpu_scp_hpri: scp-shmem@200 {
		compatible = "arm,juno-scp-shmem";
		reg = <0x200 0x200>;
	};
};

mailbox: mailbox0@40000000 {
	....
	#mbox-cells = <1>;
};

scpi_protocol: scpi@2e000000 {
	compatible = "arm,scpi";
	mboxes = <&mailbox 0 &mailbox 1>;
	shmem = <&cpu_scp_lpri &cpu_scp_hpri>;

	clocks {
		compatible = "arm,scpi-clocks";

		scpi_dvfs: scpi_clocks@0 {
			compatible = "arm,scpi-dvfs-clocks";
			#clock-cells = <1>;
			clock-indices = <0>, <1>, <2>;
			clock-output-names = "atlclk", "aplclk","gpuclk";
		};
		scpi_clk: scpi_clocks@3 {
			compatible = "arm,scpi-variable-clocks";
			#clock-cells = <1>;
			clock-indices = <3>, <4>;
			clock-output-names = "pxlclk0", "pxlclk1";
		};
	};

	scpi_sensors0: sensors {
		compatible = "arm,scpi-sensors";
		#thermal-sensor-cells = <1>;
	};
};

cpu@0 {
	...
	reg = <0 0>;
	clocks = <&scpi_dvfs 0>;
};

hdlcd@7ff60000 {
	...
	reg = <0 0x7ff60000 0 0x1000>;
	clocks = <&scpi_clk 4>;
};

thermal-zones {
	soc_thermal {
		polling-delay-passive = <100>;
		polling-delay = <1000>;

				/* sensor         ID */
		thermal-sensors = <&scpi_sensors0 3>;
		...
	};
};

In the above example, the #clock-cells is set to 1 as required.
scpi_dvfs has 3 output clocks namely: atlclk, aplclk, and gpuclk with 0,
1 and 2 as clock-indices. scpi_clk has 2 output clocks namely: pxlclk0
and pxlclk1 with 3 and 4 as clock-indices.

The first consumer in the example is cpu@0 and it has '0' as the clock
specifier which points to the first entry in the output clocks of
scpi_dvfs i.e. "atlclk".

Similarly the second example is hdlcd@7ff60000 and it has pxlclk1 as input
clock. '4' in the clock specifier here points to the second entry
in the output clocks of scpi_clocks  i.e. "pxlclk1"

The thermal-sensors property in the soc_thermal node uses the
temperature sensor provided by SCP firmware to setup a thermal
zone. The ID "3" is the sensor identifier for the temperature sensor
as used by the firmware.
Commit	Line	Data
80f390ea SH	1	System Control and Power Interface (SCPI) Message Protocol
	2	----------------------------------------------------------
	3
	4	Firmware implementing the SCPI described in ARM document number ARM DUI 0922B
	5	("ARM Compute Subsystem SCP: Message Interface Protocols")[0] can be used
	6	by Linux to initiate various system control and power operations.
	7
	8	Required properties:
	9
	10	- compatible : should be "arm,scpi"
	11	- mboxes: List of phandle and mailbox channel specifiers
	12	All the channels reserved by remote SCP firmware for use by
	13	SCPI message protocol should be specified in any order
	14	- shmem : List of phandle pointing to the shared memory(SHM) area between the
	15	processors using these mailboxes for IPC, one for each mailbox
	16	SHM can be any memory reserved for the purpose of this communication
	17	between the processors.
	18
	19	See Documentation/devicetree/bindings/mailbox/mailbox.txt
	20	for more details about the generic mailbox controller and
	21	client driver bindings.
	22
	23	Clock bindings for the clocks based on SCPI Message Protocol
	24	------------------------------------------------------------
	25
	26	This binding uses the common clock binding[1].
	27
	28	Container Node
	29	==============
	30	Required properties:
	31	- compatible : should be "arm,scpi-clocks"
	32	All the clocks provided by SCP firmware via SCPI message
	33	protocol much be listed as sub-nodes under this node.
	34
	35	Sub-nodes
	36	=========
	37	Required properties:
	38	- compatible : shall include one of the following
	39	"arm,scpi-dvfs-clocks" - all the clocks that are variable and index based.
	40	These clocks don't provide an entire range of values between the
	41	limits but only discrete points within the range. The firmware
	42	provides the mapping for each such operating frequency and the
	43	index associated with it. The firmware also manages the
	44	voltage scaling appropriately with the clock scaling.
	45	"arm,scpi-variable-clocks" - all the clocks that are variable and provide full
	46	range within the specified range. The firmware provides the
	47	range of values within a specified range.
	48
	49	Other required properties for all clocks(all from common clock binding):
	50	- #clock-cells : Should be 1. Contains the Clock ID value used by SCPI commands.
	51	- clock-output-names : shall be the corresponding names of the outputs.
	52	- clock-indices: The identifying number for the clocks(i.e.clock_id) in the
	53	node. It can be non linear and hence provide the mapping of identifiers
	54	into the clock-output-names array.
	55
	56	SRAM and Shared Memory for SCPI
	57	-------------------------------
	58
	59	A small area of SRAM is reserved for SCPI communication between application
	60	processors and SCP.
	61
	62	Required properties:
	63	- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno
	64
65	The rest of the properties should follow the generic mmio-sram description
22697acd	66	found in ../../sram/sram.txt
80f390ea SH	67
	68	Each sub-node represents the reserved area for SCPI.
	69
	70	Required sub-node properties:
	71	- reg : The base offset and size of the reserved area with the SRAM
	72	- compatible : should be "arm,juno-scp-shmem" for Non-secure SRAM based
	73	shared memory on Juno platforms
	74
d8a44fe7 PA	75	Sensor bindings for the sensors based on SCPI Message Protocol
	76	--------------------------------------------------------------
	77	SCPI provides an API to access the various sensors on the SoC.
	78
	79	Required properties:
	80	- compatible : should be "arm,scpi-sensors".
	81	- #thermal-sensor-cells: should be set to 1. This property follows the
	82	thermal device tree bindings[2].
	83
	84	Valid cell values are raw identifiers (Sensor
	85	ID) as used by the firmware. Refer to
	86	platform documentation for your
	87	implementation for the IDs to use. For Juno
	88	R0 and Juno R1 refer to [3].
	89
80f390ea SH	90	[0] http://infocenter.arm.com/help/topic/com.arm.doc.dui0922b/index.html
80f390ea SH	91	[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
d8a44fe7 PA	92	[2] Documentation/devicetree/bindings/thermal/thermal.txt
d8a44fe7 PA	93	[3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/apas03s22.html
80f390ea SH	94
	95	Example:
	96
	97	sram: sram@50000000 {
	98	compatible = "arm,juno-sram-ns", "mmio-sram";
	99	reg = <0x0 0x50000000 0x0 0x10000>;
	100
	101	#address-cells = <1>;
	102	#size-cells = <1>;
	103	ranges = <0 0x0 0x50000000 0x10000>;
	104
	105	cpu_scp_lpri: scp-shmem@0 {
	106	compatible = "arm,juno-scp-shmem";
	107	reg = <0x0 0x200>;
	108	};
	109
	110	cpu_scp_hpri: scp-shmem@200 {
	111	compatible = "arm,juno-scp-shmem";
	112	reg = <0x200 0x200>;
	113	};
	114	};
	115
	116	mailbox: mailbox0@40000000 {
	117	....
	118	#mbox-cells = <1>;
	119	};
	120
	121	scpi_protocol: scpi@2e000000 {
	122	compatible = "arm,scpi";
	123	mboxes = <&mailbox 0 &mailbox 1>;
	124	shmem = <&cpu_scp_lpri &cpu_scp_hpri>;
	125
	126	clocks {
	127	compatible = "arm,scpi-clocks";
	128
	129	scpi_dvfs: scpi_clocks@0 {
	130	compatible = "arm,scpi-dvfs-clocks";
	131	#clock-cells = <1>;
	132	clock-indices = <0>, <1>, <2>;
	133	clock-output-names = "atlclk", "aplclk","gpuclk";
	134	};
	135	scpi_clk: scpi_clocks@3 {
	136	compatible = "arm,scpi-variable-clocks";
	137	#clock-cells = <1>;
	138	clock-indices = <3>, <4>;
	139	clock-output-names = "pxlclk0", "pxlclk1";
	140	};
	141	};
d8a44fe7 PA	142
	143	scpi_sensors0: sensors {
	144	compatible = "arm,scpi-sensors";
	145	#thermal-sensor-cells = <1>;
	146	};
80f390ea SH	147	};
	148
	149	cpu@0 {
	150	...
	151	reg = <0 0>;
	152	clocks = <&scpi_dvfs 0>;
	153	};
	154
	155	hdlcd@7ff60000 {
	156	...
	157	reg = <0 0x7ff60000 0 0x1000>;
	158	clocks = <&scpi_clk 4>;
	159	};
	160
d8a44fe7 PA	161	thermal-zones {
	162	soc_thermal {
	163	polling-delay-passive = <100>;
	164	polling-delay = <1000>;
	165
	166	/* sensor ID */
	167	thermal-sensors = <&scpi_sensors0 3>;
	168	...
	169	};
	170	};
	171
80f390ea SH	172	In the above example, the #clock-cells is set to 1 as required.
	173	scpi_dvfs has 3 output clocks namely: atlclk, aplclk, and gpuclk with 0,
	174	1 and 2 as clock-indices. scpi_clk has 2 output clocks namely: pxlclk0
	175	and pxlclk1 with 3 and 4 as clock-indices.
	176
	177	The first consumer in the example is cpu@0 and it has '0' as the clock
	178	specifier which points to the first entry in the output clocks of
	179	scpi_dvfs i.e. "atlclk".
	180
	181	Similarly the second example is hdlcd@7ff60000 and it has pxlclk1 as input
	182	clock. '4' in the clock specifier here points to the second entry
	183	in the output clocks of scpi_clocks i.e. "pxlclk1"
d8a44fe7 PA	184
	185	The thermal-sensors property in the soc_thermal node uses the
	186	temperature sensor provided by SCP firmware to setup a thermal
	187	zone. The ID "3" is the sensor identifier for the temperature sensor
	188	as used by the firmware.