dt-bindings: arm: Convert PSCI binding to json-schema

Convert the PSCI binding to use DT schema format.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
new file mode 100644
index 000000000000..7abdf58b335e
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/psci.yaml
@@ -0,0 +1,163 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/psci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Power State Coordination Interface (PSCI)
+
+maintainers:
+  - Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+
+description: |+
+  Firmware implementing the PSCI functions described in ARM document number
+  ARM DEN 0022A ("Power State Coordination Interface System Software on ARM
+  processors") can be used by Linux to initiate various CPU-centric power
+  operations.
+
+  Issue A of the specification describes functions for CPU suspend, hotplug
+  and migration of secure software.
+
+  Functions are invoked by trapping to the privilege level of the PSCI
+  firmware (specified as part of the binding below) and passing arguments
+  in a manner similar to that specified by AAPCS:
+
+     r0       => 32-bit Function ID / return value
+    {r1 - r3}	=> Parameters
+
+  Note that the immediate field of the trapping instruction must be set
+  to #0.
+
+  [2] Power State Coordination Interface (PSCI) specification
+    http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+
+properties:
+  compatible:
+    oneOf:
+      - description:
+          For implementations complying to PSCI versions prior to 0.2.
+        const: arm,psci
+
+      - description:
+          For implementations complying to PSCI 0.2.
+        const: arm,psci-0.2
+
+      - description:
+          For implementations complying to PSCI 0.2.
+          Function IDs are not required and should be ignored by an OS with
+          PSCI 0.2 support, but are permitted to be present for compatibility
+          with existing software when "arm,psci" is later in the compatible
+          list.
+        items:
+          - const: arm,psci-0.2
+          - const: arm,psci
+
+      - description:
+          For implementations complying to PSCI 1.0.
+        const: arm,psci-1.0
+
+      - description:
+          For implementations complying to PSCI 1.0.
+          PSCI 1.0 is backward compatible with PSCI 0.2 with minor
+          specification updates, as defined in the PSCI specification[2].
+        items:
+          - const: arm,psci-1.0
+          - const: arm,psci-0.2
+
+  method:
+    description: The method of calling the PSCI firmware.
+    allOf:
+      - $ref: /schemas/types.yaml#/definitions/string-array
+      - enum:
+          # SMC #0, with the register assignments specified in this binding.
+          - smc
+          # HVC #0, with the register assignments specified in this binding.
+          - hvc
+
+  cpu_suspend:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Function ID for CPU_SUSPEND operation
+
+  cpu_off:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Function ID for CPU_OFF operation
+
+  cpu_on:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Function ID for CPU_ON operation
+
+  migrate:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Function ID for MIGRATE operation
+
+  arm,psci-suspend-param:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      power_state parameter to pass to the PSCI suspend call.
+
+      Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie
+      idle state nodes with entry-method property is set to "psci", as per
+      bindings in [1]) must specify this property.
+
+      [1] Kernel documentation - ARM idle states bindings
+        Documentation/devicetree/bindings/arm/idle-states.txt
+
+
+required:
+  - compatible
+  - method
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: arm,psci
+    then:
+      required:
+        - cpu_off
+        - cpu_on
+
+examples:
+  - |+
+
+    // Case 1: PSCI v0.1 only.
+
+    psci {
+      compatible      = "arm,psci";
+      method          = "smc";
+      cpu_suspend     = <0x95c10000>;
+      cpu_off         = <0x95c10001>;
+      cpu_on          = <0x95c10002>;
+      migrate         = <0x95c10003>;
+    };
+
+  - |+
+
+    // Case 2: PSCI v0.2 only
+
+    psci {
+      compatible      = "arm,psci-0.2";
+      method          = "smc";
+    };
+
+
+  - |+
+
+    // Case 3: PSCI v0.2 and PSCI v0.1.
+
+    /*
+     * A DTB may provide IDs for use by kernels without PSCI 0.2 support,
+     * enabling firmware and hypervisors to support existing and new kernels.
+     * These IDs will be ignored by kernels with PSCI 0.2 support, which will
+     * use the standard PSCI 0.2 IDs exclusively.
+     */
+
+    psci {
+      compatible = "arm,psci-0.2", "arm,psci";
+      method = "hvc";
+
+      cpu_on = <0x95c10002>;
+      cpu_off = <0x95c10001>;
+    };
+...