Documentation/devicetree/bindings/arm/topology.txt - nest-learning-thermostat/5.9.3/linux-imx-ul - Git at Google

 ===========================================
 ARM topology binding description
 ===========================================

 ===========================================
 1 - Introduction
 ===========================================

 In an ARM system, the hierarchy of CPUs is defined through three entities that
 are used to describe the layout of physical CPUs in the system:

 - cluster
 - core
 - thread

 The cpu nodes (bindings defined in [1]) represent the devices that
 correspond to physical CPUs and are to be mapped to the hierarchy levels.

 The bottom hierarchy level sits at core or thread level depending on whether
 symmetric multi-threading (SMT) is supported or not.

 For instance in a system where CPUs support SMT, "cpu" nodes represent all
 threads existing in the system and map to the hierarchy level "thread" above.
 In systems where SMT is not supported "cpu" nodes represent all cores present
 in the system and map to the hierarchy level "core" above.

 ARM topology bindings allow one to associate cpu nodes with hierarchical groups
 corresponding to the system hierarchy; syntactically they are defined as device
 tree nodes.

 The remainder of this document provides the topology bindings for ARM, based
 on the ePAPR standard, available from:

 http://www.power.org/documentation/epapr-version-1-1/

 If not stated otherwise, whenever a reference to a cpu node phandle is made its
 value must point to a cpu node compliant with the cpu node bindings as
 documented in [1].
 A topology description containing phandles to cpu nodes that are not compliant
 with bindings standardized in [1] is therefore considered invalid.

 ===========================================
 2 - cpu-map node
 ===========================================

 The ARM CPU topology is defined within the cpu-map node, which is a direct
 child of the cpus node and provides a container where the actual topology
 nodes are listed.

 - cpu-map node

 	Usage: Optional - On ARM SMP systems provide CPUs topology to the OS.
 			  ARM uniprocessor systems do not require a topology
 			  description and therefore should not define a
 			  cpu-map node.

 	Description: The cpu-map node is just a container node where its
 		     subnodes describe the CPU topology.

 	Node name must be "cpu-map".

 	The cpu-map node's parent node must be the cpus node.

 	The cpu-map node's child nodes can be:

 	- one or more cluster nodes

 	Any other configuration is considered invalid.

 The cpu-map node can only contain three types of child nodes:

 - cluster node
 - core node
 - thread node

 whose bindings are described in paragraph 3.

 The nodes describing the CPU topology (cluster/core/thread) can only
 be defined within the cpu-map node and every core/thread in the system
 must be defined within the topology.  Any other configuration is
 invalid and therefore must be ignored.

 ===========================================
 2.1 - cpu-map child nodes naming convention
 ===========================================

 cpu-map child nodes must follow a naming convention where the node name
 must be "clusterN", "coreN", "threadN" depending on the node type (ie
 cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which
 are siblings within a single common parent node must be given a unique and
 sequential N value, starting from 0).
 cpu-map child nodes which do not share a common parent node can have the same
 name (ie same number N as other cpu-map child nodes at different device tree
 levels) since name uniqueness will be guaranteed by the device tree hierarchy.

 ===========================================
 3 - cluster/core/thread node bindings
 ===========================================

 Bindings for cluster/cpu/thread nodes are defined as follows:

 - cluster node

 	 Description: must be declared within a cpu-map node, one node
 		      per cluster. A system can contain several layers of
 		      clustering and cluster nodes can be contained in parent
 		      cluster nodes.

 	The cluster node name must be "clusterN" as described in 2.1 above.
 	A cluster node can not be a leaf node.

 	A cluster node's child nodes must be:

 	- one or more cluster nodes; or
 	- one or more core nodes

 	Any other configuration is considered invalid.

 - core node

 	Description: must be declared in a cluster node, one node per core in
 		     the cluster. If the system does not support SMT, core
 		     nodes are leaf nodes, otherwise they become containers of
 		     thread nodes.

 	The core node name must be "coreN" as described in 2.1 above.

 	A core node must be a leaf node if SMT is not supported.

 	Properties for core nodes that are leaf nodes:

 	- cpu
 		Usage: required
 		Value type: <phandle>
 		Definition: a phandle to the cpu node that corresponds to the
 			    core node.

 	If a core node is not a leaf node (CPUs supporting SMT) a core node's
 	child nodes can be:

 	- one or more thread nodes

 	Any other configuration is considered invalid.

 - thread node

 	Description: must be declared in a core node, one node per thread
 		     in the core if the system supports SMT. Thread nodes are
 		     always leaf nodes in the device tree.

 	The thread node name must be "threadN" as described in 2.1 above.

 	A thread node must be a leaf node.

 	A thread node must contain the following property:

 	- cpu
 		Usage: required
 		Value type: <phandle>
 		Definition: a phandle to the cpu node that corresponds to
 			    the thread node.

 ===========================================
 4 - Example dts
 ===========================================

 Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters):

 cpus {
 	#size-cells = <0>;
 	#address-cells = <2>;

 	cpu-map {
 		cluster0 {
 			cluster0 {
 				core0 {
 					thread0 {
 						cpu = <&CPU0>;
 					};
 					thread1 {
 						cpu = <&CPU1>;
 					};
 				};

 				core1 {
 					thread0 {
 						cpu = <&CPU2>;
 					};
 					thread1 {
 						cpu = <&CPU3>;
 					};
 				};
 			};

 			cluster1 {
 				core0 {
 					thread0 {
 						cpu = <&CPU4>;
 					};
 					thread1 {
 						cpu = <&CPU5>;
 					};
 				};

 				core1 {
 					thread0 {
 						cpu = <&CPU6>;
 					};
 					thread1 {
 						cpu = <&CPU7>;
 					};
 				};
 			};
 		};

 		cluster1 {
 			cluster0 {
 				core0 {
 					thread0 {
 						cpu = <&CPU8>;
 					};
 					thread1 {
 						cpu = <&CPU9>;
 					};
 				};
 				core1 {
 					thread0 {
 						cpu = <&CPU10>;
 					};
 					thread1 {
 						cpu = <&CPU11>;
 					};
 				};
 			};

 			cluster1 {
 				core0 {
 					thread0 {
 						cpu = <&CPU12>;
 					};
 					thread1 {
 						cpu = <&CPU13>;
 					};
 				};
 				core1 {
 					thread0 {
 						cpu = <&CPU14>;
 					};
 					thread1 {
 						cpu = <&CPU15>;
 					};
 				};
 			};
 		};
 	};

 	CPU0: cpu@0 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x0>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU1: cpu@1 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x1>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU2: cpu@100 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x100>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU3: cpu@101 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x101>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU4: cpu@10000 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x10000>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU5: cpu@10001 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x10001>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU6: cpu@10100 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x10100>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU7: cpu@10101 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x0 0x10101>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU8: cpu@100000000 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x0>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU9: cpu@100000001 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x1>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU10: cpu@100000100 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x100>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU11: cpu@100000101 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x101>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU12: cpu@100010000 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x10000>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU13: cpu@100010001 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x10001>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU14: cpu@100010100 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x10100>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};

 	CPU15: cpu@100010101 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a57";
 		reg = <0x1 0x10101>;
 		enable-method = "spin-table";
 		cpu-release-addr = <0 0x20000000>;
 	};
 };

 Example 2 (ARM 32-bit, dual-cluster, 8-cpu system, no SMT):

 cpus {
 	#size-cells = <0>;
 	#address-cells = <1>;

 	cpu-map {
 		cluster0 {
 			core0 {
 				cpu = <&CPU0>;
 			};
 			core1 {
 				cpu = <&CPU1>;
 			};
 			core2 {
 				cpu = <&CPU2>;
 			};
 			core3 {
 				cpu = <&CPU3>;
 			};
 		};

 		cluster1 {
 			core0 {
 				cpu = <&CPU4>;
 			};
 			core1 {
 				cpu = <&CPU5>;
 			};
 			core2 {
 				cpu = <&CPU6>;
 			};
 			core3 {
 				cpu = <&CPU7>;
 			};
 		};
 	};

 	CPU0: cpu@0 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a15";
 		reg = <0x0>;
 	};

 	CPU1: cpu@1 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a15";
 		reg = <0x1>;
 	};

 	CPU2: cpu@2 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a15";
 		reg = <0x2>;
 	};

 	CPU3: cpu@3 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a15";
 		reg = <0x3>;
 	};

 	CPU4: cpu@100 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a7";
 		reg = <0x100>;
 	};

 	CPU5: cpu@101 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a7";
 		reg = <0x101>;
 	};

 	CPU6: cpu@102 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a7";
 		reg = <0x102>;
 	};

 	CPU7: cpu@103 {
 		device_type = "cpu";
 		compatible = "arm,cortex-a7";
 		reg = <0x103>;
 	};
 };

 ===============================================================================
 [1] ARM Linux kernel documentation
     Documentation/devicetree/bindings/arm/cpus.txt
	===========================================
	ARM topology binding description
	===========================================

	===========================================
	1 - Introduction
	===========================================

	In an ARM system, the hierarchy of CPUs is defined through three entities that
	are used to describe the layout of physical CPUs in the system:

	- cluster
	- core
	- thread

	The cpu nodes (bindings defined in [1]) represent the devices that
	correspond to physical CPUs and are to be mapped to the hierarchy levels.

	The bottom hierarchy level sits at core or thread level depending on whether
	symmetric multi-threading (SMT) is supported or not.

	For instance in a system where CPUs support SMT, "cpu" nodes represent all
	threads existing in the system and map to the hierarchy level "thread" above.
	In systems where SMT is not supported "cpu" nodes represent all cores present
	in the system and map to the hierarchy level "core" above.

	ARM topology bindings allow one to associate cpu nodes with hierarchical groups
	corresponding to the system hierarchy; syntactically they are defined as device
	tree nodes.

	The remainder of this document provides the topology bindings for ARM, based
	on the ePAPR standard, available from:

	http://www.power.org/documentation/epapr-version-1-1/

	If not stated otherwise, whenever a reference to a cpu node phandle is made its
	value must point to a cpu node compliant with the cpu node bindings as
	documented in [1].
	A topology description containing phandles to cpu nodes that are not compliant
	with bindings standardized in [1] is therefore considered invalid.

	===========================================
	2 - cpu-map node
	===========================================

	The ARM CPU topology is defined within the cpu-map node, which is a direct
	child of the cpus node and provides a container where the actual topology
	nodes are listed.

	- cpu-map node

	Usage: Optional - On ARM SMP systems provide CPUs topology to the OS.
	ARM uniprocessor systems do not require a topology
	description and therefore should not define a
	cpu-map node.

	Description: The cpu-map node is just a container node where its
	subnodes describe the CPU topology.

	Node name must be "cpu-map".

	The cpu-map node's parent node must be the cpus node.

	The cpu-map node's child nodes can be:

	- one or more cluster nodes

	Any other configuration is considered invalid.

	The cpu-map node can only contain three types of child nodes:

	- cluster node
	- core node
	- thread node

	whose bindings are described in paragraph 3.

	The nodes describing the CPU topology (cluster/core/thread) can only
	be defined within the cpu-map node and every core/thread in the system
	must be defined within the topology. Any other configuration is
	invalid and therefore must be ignored.

	===========================================
	2.1 - cpu-map child nodes naming convention
	===========================================

	cpu-map child nodes must follow a naming convention where the node name
	must be "clusterN", "coreN", "threadN" depending on the node type (ie
	cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which
	are siblings within a single common parent node must be given a unique and
	sequential N value, starting from 0).
	cpu-map child nodes which do not share a common parent node can have the same
	name (ie same number N as other cpu-map child nodes at different device tree
	levels) since name uniqueness will be guaranteed by the device tree hierarchy.

	===========================================
	3 - cluster/core/thread node bindings
	===========================================

	Bindings for cluster/cpu/thread nodes are defined as follows:

	- cluster node

	Description: must be declared within a cpu-map node, one node
	per cluster. A system can contain several layers of
	clustering and cluster nodes can be contained in parent
	cluster nodes.

	The cluster node name must be "clusterN" as described in 2.1 above.
	A cluster node can not be a leaf node.

	A cluster node's child nodes must be:

	- one or more cluster nodes; or
	- one or more core nodes

	Any other configuration is considered invalid.

	- core node

	Description: must be declared in a cluster node, one node per core in
	the cluster. If the system does not support SMT, core
	nodes are leaf nodes, otherwise they become containers of
	thread nodes.

	The core node name must be "coreN" as described in 2.1 above.

	A core node must be a leaf node if SMT is not supported.

	Properties for core nodes that are leaf nodes:

	- cpu
	Usage: required
	Value type: <phandle>
	Definition: a phandle to the cpu node that corresponds to the
	core node.

	If a core node is not a leaf node (CPUs supporting SMT) a core node's
	child nodes can be:

	- one or more thread nodes

	Any other configuration is considered invalid.

	- thread node

	Description: must be declared in a core node, one node per thread
	in the core if the system supports SMT. Thread nodes are
	always leaf nodes in the device tree.

	The thread node name must be "threadN" as described in 2.1 above.

	A thread node must be a leaf node.

	A thread node must contain the following property:

	- cpu
	Usage: required
	Value type: <phandle>
	Definition: a phandle to the cpu node that corresponds to
	the thread node.

	===========================================
	4 - Example dts
	===========================================

	Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters):

	cpus {
	#size-cells = <0>;
	#address-cells = <2>;

	cpu-map {
	cluster0 {
	cluster0 {
	core0 {
	thread0 {
	cpu = <&CPU0>;
	};
	thread1 {
	cpu = <&CPU1>;
	};
	};

	core1 {
	thread0 {
	cpu = <&CPU2>;
	};
	thread1 {
	cpu = <&CPU3>;
	};
	};
	};

	cluster1 {
	core0 {
	thread0 {
	cpu = <&CPU4>;
	};
	thread1 {
	cpu = <&CPU5>;
	};
	};

	core1 {
	thread0 {
	cpu = <&CPU6>;
	};
	thread1 {
	cpu = <&CPU7>;
	};
	};
	};
	};

	cluster1 {
	cluster0 {
	core0 {
	thread0 {
	cpu = <&CPU8>;
	};
	thread1 {
	cpu = <&CPU9>;
	};
	};
	core1 {
	thread0 {
	cpu = <&CPU10>;
	};
	thread1 {
	cpu = <&CPU11>;
	};
	};
	};

	cluster1 {
	core0 {
	thread0 {
	cpu = <&CPU12>;
	};
	thread1 {
	cpu = <&CPU13>;
	};
	};
	core1 {
	thread0 {
	cpu = <&CPU14>;
	};
	thread1 {
	cpu = <&CPU15>;
	};
	};
	};
	};
	};

	CPU0: cpu@0 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x0>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU1: cpu@1 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x1>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU2: cpu@100 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x100>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU3: cpu@101 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x101>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU4: cpu@10000 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x10000>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU5: cpu@10001 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x10001>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU6: cpu@10100 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x10100>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU7: cpu@10101 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x0 0x10101>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU8: cpu@100000000 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x0>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU9: cpu@100000001 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x1>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU10: cpu@100000100 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x100>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU11: cpu@100000101 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x101>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU12: cpu@100010000 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x10000>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU13: cpu@100010001 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x10001>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU14: cpu@100010100 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x10100>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};

	CPU15: cpu@100010101 {
	device_type = "cpu";
	compatible = "arm,cortex-a57";
	reg = <0x1 0x10101>;
	enable-method = "spin-table";
	cpu-release-addr = <0 0x20000000>;
	};
	};

	Example 2 (ARM 32-bit, dual-cluster, 8-cpu system, no SMT):

	cpus {
	#size-cells = <0>;
	#address-cells = <1>;

	cpu-map {
	cluster0 {
	core0 {
	cpu = <&CPU0>;
	};
	core1 {
	cpu = <&CPU1>;
	};
	core2 {
	cpu = <&CPU2>;
	};
	core3 {
	cpu = <&CPU3>;
	};
	};

	cluster1 {
	core0 {
	cpu = <&CPU4>;
	};
	core1 {
	cpu = <&CPU5>;
	};
	core2 {
	cpu = <&CPU6>;
	};
	core3 {
	cpu = <&CPU7>;
	};
	};
	};

	CPU0: cpu@0 {
	device_type = "cpu";
	compatible = "arm,cortex-a15";
	reg = <0x0>;
	};

	CPU1: cpu@1 {
	device_type = "cpu";
	compatible = "arm,cortex-a15";
	reg = <0x1>;
	};

	CPU2: cpu@2 {
	device_type = "cpu";
	compatible = "arm,cortex-a15";
	reg = <0x2>;
	};

	CPU3: cpu@3 {
	device_type = "cpu";
	compatible = "arm,cortex-a15";
	reg = <0x3>;
	};

	CPU4: cpu@100 {
	device_type = "cpu";
	compatible = "arm,cortex-a7";
	reg = <0x100>;
	};

	CPU5: cpu@101 {
	device_type = "cpu";
	compatible = "arm,cortex-a7";
	reg = <0x101>;
	};

	CPU6: cpu@102 {
	device_type = "cpu";
	compatible = "arm,cortex-a7";
	reg = <0x102>;
	};

	CPU7: cpu@103 {
	device_type = "cpu";
	compatible = "arm,cortex-a7";
	reg = <0x103>;
	};
	};

	===============================================================================
	[1] ARM Linux kernel documentation
	Documentation/devicetree/bindings/arm/cpus.txt