dt: psci: Update DT bindings to support hierarchical PSCI states

Update PSCI DT bindings to allow to represent idle states for CPUs and the
CPU topology, by using a hierarchical layout. Primarily this is done by
re-using the existing DT bindings for PM domains [1] and for PM domain idle
states [2].

Let's also add an example into the document for the PSCI DT bindings, to
clearly show the new hierarchical based layout. The currently supported
flattened layout, is already described in the ARM idle states bindings [3],
so let's leave that as is.

[1] Documentation/devicetree/bindings/power/power_domain.txt
[2] Documentation/devicetree/bindings/power/domain-idle-state.txt
[3] Documentation/devicetree/bindings/arm/idle-states.txt

Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
index c23c24ff757535f3178864ebfc0b7ac6990d3109..7a9c3ce2dbef991d87c2111609c0aff4db40ca57 100644 (file)
--- a/Documentation/devicetree/bindings/arm/cpus.yaml
+++ b/Documentation/devicetree/bindings/arm/cpus.yaml
@@ -242,6 +242,21 @@ properties:
 
       where voltage is in V, frequency is in MHz.
 
+  power-domains:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    description:
+      List of phandles and PM domain specifiers, as defined by bindings of the
+      PM domain provider (see also ../power_domain.txt).
+
+  power-domain-names:
+    $ref: '/schemas/types.yaml#/definitions/string-array'
+    description:
+      A list of power domain name strings sorted in the same order as the
+      power-domains property.
+
+      For PSCI based platforms, the name corresponding to the index of the PSCI
+      PM domain provider, must be "psci".
+
   qcom,saw:
     $ref: '/schemas/types.yaml#/definitions/phandle'
     description: |

diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
index 7abdf58b335eb82b493b3ee7fe105f551e1db4c3..8ef85420b2ab1913786fc69dd5fbfda86c8c1f0b 100644 (file)
--- a/Documentation/devicetree/bindings/arm/psci.yaml
+++ b/Documentation/devicetree/bindings/arm/psci.yaml
@@ -102,6 +102,34 @@ properties:
       [1] Kernel documentation - ARM idle states bindings
         Documentation/devicetree/bindings/arm/idle-states.txt
 
+  "#power-domain-cells":
+    description:
+      The number of cells in a PM domain specifier as per binding in [3].
+      Must be 0 as to represent a single PM domain.
+
+      ARM systems can have multiple cores, sometimes in an hierarchical
+      arrangement. This often, but not always, maps directly to the processor
+      power topology of the system. Individual nodes in a topology have their
+      own specific power states and can be better represented hierarchically.
+
+      For these cases, the definitions of the idle states for the CPUs and the
+      CPU topology, must conform to the binding in [3]. The idle states
+      themselves must conform to the binding in [4] and must specify the
+      arm,psci-suspend-param property.
+
+      It should also be noted that, in PSCI firmware v1.0 the OS-Initiated
+      (OSI) CPU suspend mode is introduced. Using a hierarchical representation
+      helps to implement support for OSI mode and OS implementations may choose
+      to mandate it.
+
+      [3] Documentation/devicetree/bindings/power/power_domain.txt
+      [4] Documentation/devicetree/bindings/power/domain-idle-state.txt
+
+  power-domains:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    description:
+      List of phandles and PM domain specifiers, as defined by bindings of the
+      PM domain provider.
 
 required:
   - compatible
@@ -160,4 +188,80 @@ examples:
       cpu_on = <0x95c10002>;
       cpu_off = <0x95c10001>;
     };
+
+  - |+
+
+    // Case 4: CPUs and CPU idle states described using the hierarchical model.
+
+    cpus {
+      #size-cells = <0>;
+      #address-cells = <1>;
+
+      CPU0: cpu@0 {
+        device_type = "cpu";
+        compatible = "arm,cortex-a53", "arm,armv8";
+        reg = <0x0>;
+        enable-method = "psci";
+        power-domains = <&CPU_PD0>;
+        power-domain-names = "psci";
+      };
+
+      CPU1: cpu@1 {
+        device_type = "cpu";
+        compatible = "arm,cortex-a57", "arm,armv8";
+        reg = <0x100>;
+        enable-method = "psci";
+        power-domains = <&CPU_PD1>;
+        power-domain-names = "psci";
+      };
+
+      idle-states {
+
+        CPU_PWRDN: cpu-power-down {
+          compatible = "arm,idle-state";
+          arm,psci-suspend-param = <0x0000001>;
+          entry-latency-us = <10>;
+          exit-latency-us = <10>;
+          min-residency-us = <100>;
+        };
+
+        CLUSTER_RET: cluster-retention {
+          compatible = "domain-idle-state";
+          arm,psci-suspend-param = <0x1000011>;
+          entry-latency-us = <500>;
+          exit-latency-us = <500>;
+          min-residency-us = <2000>;
+        };
+
+        CLUSTER_PWRDN: cluster-power-down {
+          compatible = "domain-idle-state";
+          arm,psci-suspend-param = <0x1000031>;
+          entry-latency-us = <2000>;
+          exit-latency-us = <2000>;
+          min-residency-us = <6000>;
+        };
+      };
+    };
+
+    psci {
+      compatible = "arm,psci-1.0";
+      method = "smc";
+
+      CPU_PD0: cpu-pd0 {
+        #power-domain-cells = <0>;
+        domain-idle-states = <&CPU_PWRDN>;
+        power-domains = <&CLUSTER_PD>;
+      };
+
+      CPU_PD1: cpu-pd1 {
+        #power-domain-cells = <0>;
+        domain-idle-states =  <&CPU_PWRDN>;
+        power-domains = <&CLUSTER_PD>;
+      };
+
+      CLUSTER_PD: cluster-pd {
+        #power-domain-cells = <0>;
+        domain-idle-states = <&CLUSTER_RET>, <&CLUSTER_PWRDN>;
+      };
+    };
 ...