diff options
| -rw-r--r-- | Documentation/devicetree/bindings/arm/topology.txt | 172 |
1 files changed, 99 insertions, 73 deletions
diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/arm/topology.txt index b0d80c0fb265..3b8febb46dad 100644 --- a/Documentation/devicetree/bindings/arm/topology.txt +++ b/Documentation/devicetree/bindings/arm/topology.txt @@ -9,6 +9,7 @@ ARM topology binding description 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: +- socket - cluster - core - thread @@ -63,21 +64,23 @@ nodes are listed. The cpu-map node's child nodes can be: - - one or more cluster nodes + - one or more cluster nodes or + - one or more socket nodes in a multi-socket system Any other configuration is considered invalid. -The cpu-map node can only contain three types of child nodes: +The cpu-map node can only contain 4 types of child nodes: +- socket node - 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 +The nodes describing the CPU topology (socket/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. =========================================== @@ -85,26 +88,44 @@ invalid and therefore must be ignored. =========================================== 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 +must be "socketN", "clusterN", "coreN", "threadN" depending on the node type +(ie socket/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 +3 - socket/cluster/core/thread node bindings =========================================== -Bindings for cluster/cpu/thread nodes are defined as follows: +Bindings for socket/cluster/cpu/thread nodes are defined as follows: + +- socket node + + Description: must be declared within a cpu-map node, one node + per physical socket in the system. A system can + contain single or multiple physical socket. + The association of sockets and NUMA nodes is beyond + the scope of this bindings, please refer [2] for + NUMA bindings. + + This node is optional for a single socket system. + + The socket node name must be "socketN" as described in 2.1 above. + A socket node can not be a leaf node. + + A socket node's child nodes must be one or more cluster nodes. + + Any other configuration is considered invalid. - 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. + clustering within a single physical socket 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. @@ -164,90 +185,93 @@ Bindings for cluster/cpu/thread nodes are defined as follows: 4 - Example dts =========================================== -Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters): +Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters in a single +physical socket): cpus { #size-cells = <0>; #address-cells = <2>; cpu-map { - cluster0 { + socket0 { cluster0 { - core0 { - thread0 { - cpu = <&CPU0>; - }; - thread1 { - cpu = <&CPU1>; + cluster0 { + core0 { + thread0 { + cpu = <&CPU0>; + }; + thread1 { + cpu = <&CPU1>; + }; }; - }; - core1 { - thread0 { - cpu = <&CPU2>; - }; - thread1 { - cpu = <&CPU3>; + core1 { + thread0 { + cpu = <&CPU2>; + }; + thread1 { + cpu = <&CPU3>; + }; }; }; - }; - cluster1 { - core0 { - thread0 { - cpu = <&CPU4>; - }; - thread1 { - cpu = <&CPU5>; + 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>; + core1 { + thread0 { + cpu = <&CPU6>; + }; + thread1 { + cpu = <&CPU7>; + }; }; }; }; cluster1 { - core0 { - thread0 { - cpu = <&CPU12>; + cluster0 { + core0 { + thread0 { + cpu = <&CPU8>; + }; + thread1 { + cpu = <&CPU9>; + }; }; - thread1 { - cpu = <&CPU13>; + core1 { + thread0 { + cpu = <&CPU10>; + }; + thread1 { + cpu = <&CPU11>; + }; }; }; - core1 { - thread0 { - cpu = <&CPU14>; + + cluster1 { + core0 { + thread0 { + cpu = <&CPU12>; + }; + thread1 { + cpu = <&CPU13>; + }; }; - thread1 { - cpu = <&CPU15>; + core1 { + thread0 { + cpu = <&CPU14>; + }; + thread1 { + cpu = <&CPU15>; + }; }; }; }; @@ -473,3 +497,5 @@ cpus { =============================================================================== [1] ARM Linux kernel documentation Documentation/devicetree/bindings/arm/cpus.yaml +[2] Devicetree NUMA binding description + Documentation/devicetree/bindings/numa.txt |