| Message ID | 1355762141-29616-4-git-send-email-will.deacon@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Monday 17 December 2012, Will Deacon wrote: > + > + - function-base : The base ID from which the functions are offset. > + > +Main node optional properties: > + > + - cpu_suspend : Offset of CPU_SUSPEND ID from function-base > + > + - cpu_off : Offset of CPU_OFF ID from function-base > + > + - cpu_on : Offset of CPU_ON ID from function-base > + > + - migrate : Offset of MIGRATE ID from function-base What is the benefit of the "function-base" property over just having 32 bit IDs for each function. For all I can tell, the interface does not rely on the numbers to be consecutive, so removing the function-base attribute would make the binding simpler as well as more flexible. Arnd
Hi Arnd, On Mon, Dec 17, 2012 at 08:00:11PM +0000, Arnd Bergmann wrote: > On Monday 17 December 2012, Will Deacon wrote: > > + > > + - function-base : The base ID from which the functions are offset. > > + > > +Main node optional properties: > > + > > + - cpu_suspend : Offset of CPU_SUSPEND ID from function-base > > + > > + - cpu_off : Offset of CPU_OFF ID from function-base > > + > > + - cpu_on : Offset of CPU_ON ID from function-base > > + > > + - migrate : Offset of MIGRATE ID from function-base > > What is the benefit of the "function-base" property over just having > 32 bit IDs for each function. For all I can tell, the interface does > not rely on the numbers to be consecutive, so removing the function-base > attribute would make the binding simpler as well as more flexible. Sure, happy to change that for v3. Will
diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt new file mode 100644 index 0000000..904d0d3 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/psci.txt @@ -0,0 +1,58 @@ +* 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 : Must be "arm,psci" + + - 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. + + - function-base : The base ID from which the functions are offset. + +Main node optional properties: + + - cpu_suspend : Offset of CPU_SUSPEND ID from function-base + + - cpu_off : Offset of CPU_OFF ID from function-base + + - cpu_on : Offset of CPU_ON ID from function-base + + - migrate : Offset of MIGRATE ID from function-base + + +Example: + + psci { + compatible = "arm,psci"; + method = "smc"; + function-base = <0x95c1ba5e>; + cpu_suspend = <0>; + cpu_off = <1>; + cpu_on = <2>; + migrate = <3>; + };
This patch adds a new devicetree binding for describing PSCI firmware to Linux. Signed-off-by: Will Deacon <will.deacon@arm.com> --- Documentation/devicetree/bindings/arm/psci.txt | 58 ++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/psci.txt