On Fri, Aug 22, 2014 at 08:49:17PM +0100, Geoff Levand wrote: > Add a new arm64 device tree binding cpu-return-addr. This binding is > recomended > for all ARM v8 CPUs that have an "enable-method" property value of > "spin-table". > The value is a 64 bit physical address that secondary CPU execution will > transfer > to upon CPU shutdown. > > Signed-off-by: Geoff Levand <[email protected]> > --- > Documentation/devicetree/bindings/arm/cpus.txt | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/Documentation/devicetree/bindings/arm/cpus.txt > b/Documentation/devicetree/bindings/arm/cpus.txt > index 1fe72a0..42d5d5f 100644 > --- a/Documentation/devicetree/bindings/arm/cpus.txt > +++ b/Documentation/devicetree/bindings/arm/cpus.txt > @@ -201,6 +201,15 @@ nodes to be present and contain the properties described > below. > property identifying a 64-bit zero-initialised > memory location. > > + - cpu-return-addr > + Usage: recomended for all ARM v8 CPUs that have an > + "enable-method" property value of "spin-table". > + Value type: <prop-encoded-array> > + Definition: > + # On ARM v8 64-bit systems must be a two cell property. > + The value is a 64 bit physical address that secondary > + CPU execution will transfer to upon CPU shutdown.
As I've been away for most of the past four weeks, I haven't read all the threads around this topic. But I don't think we ended up with a clearly agreed recommendation for cpu-return-addr. If we do, we also need to be clear on what state the CPU should be in when returned to such address (ELx, MMU, caches). In general, if we need returning to firmware I would strongly recommend PSCI but I know there is the Applied board which does not have EL3, so something like this may work. But we need to get them into discussion as well since I assume cpu-return-addr would be a firmware provided address. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
