1 files changed, 102 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt
new file mode 100644
index 000000000..5aa40ede0
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/psci.txt
@@ -0,0 +1,102 @@
+* Power State Coordination Interface (PSCI)
+
+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.
+
+
+Main node required properties:
+
+ - compatible    : should contain at least one of:
+
+				 * "arm,psci" : for implementations complying to PSCI versions prior to
+					0.2. For these cases function IDs must be provided.
+
+				 * "arm,psci-0.2" : 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.
+
+ - method        : The method of calling the PSCI firmware. Permitted
+                   values are:
+
+                   "smc" : SMC #0, with the register assignments specified
+		           in this binding.
+
+                   "hvc" : HVC #0, with the register assignments specified
+		           in this binding.
+
+Main node optional properties:
+
+ - cpu_suspend   : Function ID for CPU_SUSPEND operation
+
+ - cpu_off       : Function ID for CPU_OFF operation
+
+ - cpu_on        : Function ID for CPU_ON operation
+
+ - migrate       : Function ID for MIGRATE operation
+
+Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie idle
+state nodes, as per bindings in [1]) must specify the following properties:
+
+- arm,psci-suspend-param
+		Usage: Required for state nodes[1] if the corresponding
+                       idle-states node entry-method property is set
+                       to "psci".
+		Value type: <u32>
+		Definition: power_state parameter to pass to the PSCI
+			    suspend call.
+
+Example:
+
+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 = < arbitrary value >;
+		cpu_off = < arbitrary value >;
+
+		...
+	};
+
+[1] Kernel documentation - ARM idle states bindings
+    Documentation/devicetree/bindings/arm/idle-states.txt