From: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxx>
The PSCI v0.2+ spec defines standard values for PSCI function IDs.
Add a new binding entry so that pre v0.2 implementations can
use DT entries for function IDs and v0.2+ implementations use
standard entries as defined by the PSCIv0.2 specification.
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxx>
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
Documentation/devicetree/bindings/arm/psci.txt | 37 +++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt
index 433afe9..b4a58f3 100644
--- a/Documentation/devicetree/bindings/arm/psci.txt
+++ b/Documentation/devicetree/bindings/arm/psci.txt
@@ -21,7 +21,15 @@ to #0.
Main node required properties:
- - compatible : Must be "arm,psci"
+ - 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:
@@ -45,6 +53,8 @@ Main node optional properties:
Example:
+Case 1: PSCI v0.1 only.
+
psci {
compatible = "arm,psci";
method = "smc";
@@ -53,3 +63,28 @@ Example:
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 >;
+
+ ...
+ };
--
1.8.5.2
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