On Thu, Sep 27, 2018 at 8:03 PM Guo Ren <ren_guo@xxxxxxxxx> wrote: > > On Thu, Sep 27, 2018 at 11:43:17AM -0500, Rob Herring wrote: > > On Tue, Sep 25, 2018 at 07:39:21AM +0800, Guo Ren wrote: > > > This patch adds the documentation to describe that how to add cpu nodes in > > > dts for SMP. > > > > > > Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx> > > > --- > > > Documentation/devicetree/bindings/csky/cpus.txt | 70 +++++++++++++++++++++++++ > > > 1 file changed, 70 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/csky/cpus.txt > > > > > > diff --git a/Documentation/devicetree/bindings/csky/cpus.txt b/Documentation/devicetree/bindings/csky/cpus.txt > > > new file mode 100644 > > > index 0000000..ee3901d > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/csky/cpus.txt > > > @@ -0,0 +1,70 @@ > > > +================== > > > +C-SKY CPU Bindings > > > +================== > > > + > > > +The device tree allows to describe the layout of CPUs in a system through > > > +the "cpus" node, which in turn contains a number of subnodes (ie "cpu") > > > +defining properties for every cpu. > > > + > > > +Only SMP system need to care about the cpus node and single processor > > > +needn't define cpus node at all. > > > > We've generally found this is not true. Even for single core, you can > > have power domains, clocks for DVFS, etc. > Ok, I'll remove it. > > > > > > + > > > +===================================== > > > +cpus and cpu node bindings definition > > > +===================================== > > > + > > > +- cpus node > > > + > > > + Description: Container of cpu nodes > > > + > > > + The node name must be "cpus". > > > + > > > + A cpus node must define the following properties: > > > + > > > + - #address-cells > > > + Usage: required > > > + Value type: <u32> > > > + Definition: must be set to 1 > > > + - #size-cells > > > + Usage: required > > > + Value type: <u32> > > > + Definition: must be set to 0 > > > + > > > +- cpu node > > > + > > > + Description: Describes one of SMP cores > > > + > > > + PROPERTIES > > > + > > > > You need a compatible property for cpu nodes. > Our cpu is defined in defconfig, not in dts. I could put a comatible > property in here, but it's no use in code. It doesn't matter as that could change. Most arches do run-time selection of cpus within a range of compatible cores. And read the DT spec (devicetree.org) which says compatible is required for cpu nodes. Rob
