On Thu, Jan 15, 2015 at 02:42:23PM +0000, Rob Herring wrote: > On Thu, Jan 15, 2015 at 7:55 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > > On Thu, Jan 15, 2015 at 01:52:01PM +0000, Mark Rutland wrote: > >> On Wed, Jan 14, 2015 at 08:58:18PM +0000, Suman Anna wrote: > >> > This patch adds the generic common bindings used to represent > >> > a hwlock device and use/request locks in a device-tree build. > >> > > >> > All the platform-specific hwlock driver implementations need the > >> > number of locks and associated base id for registering the locks > >> > present within the device with the driver core. This base id > >> > needs to be unique across multiple IP instances of a hwspinlock > >> > device, so that each hwlock can be represented uniquely in a > >> > system. > >> > > >> > The number of locks is represented by 'hwlock-num-locks' property, > >> > and the base id is represented by the 'hwlock-base-id' property. > >> > The args specifier length is dependent on each vendor-specific > >> > implementation and is represented through the '#hwlock-cells' > >> > property. Client users need to use the property 'hwlocks' for > >> > requesting specific lock(s). > >> > > >> > Note that the document is named hwlock.txt deliberately to keep > >> > it a bit more generic. > >> > > >> > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > >> > Signed-off-by: Suman Anna <s-anna@xxxxxx> > >> > --- > >> > v7: Revised binding info for hwlock-base-id, it is mandatory now > >> > > >> > .../devicetree/bindings/hwlock/hwlock.txt | 55 ++++++++++++++++++++++ > >> > 1 file changed, 55 insertions(+) > >> > create mode 100644 Documentation/devicetree/bindings/hwlock/hwlock.txt > >> > > >> > diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt > >> > new file mode 100644 > >> > index 000000000000..8de7aaf878f9 > >> > --- /dev/null > >> > +++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt > >> > @@ -0,0 +1,55 @@ > >> > +Generic hwlock bindings > >> > +======================= > >> > + > >> > +Generic bindings that are common to all the hwlock platform specific driver > >> > +implementations. > >> > + > >> > +The validity and need of these common properties may vary from one platform > >> > +implementation to another. The platform specific bindings should explicitly > >> > +state if an optional property is used. Please also look through the individual > >> > +platform specific hwlock binding documentations for identifying the applicable > >> > +properties. > >> > + > >> > +Common properties: > >> > +- #hwlock-cells: Specifies the number of cells needed to represent a > >> > + specific lock. This property is mandatory for all > >> > + platform implementations. > >> > +- hwlock-num-locks: Number of locks present in a hwlock device. This > >> > + property is needed on hwlock devices, where the number > >> > + of supported locks within a hwlock device cannot be > >> > + read from a register. > >> > +- hwlock-base-id: An unique base Id for the locks for a particular hwlock > >> > + device. This property is mandatory for all platform > >> > + implementations. > >> > >> This property makes no sense. The ID encoded in the hwlock cells is > >> relative to the instance (identified by phandle), not global. So the DT > >> has no global ID space. > >> > >> Why do you think you need this? > > > > Having looked at the way this proeprty is used, NAK. > > > > If you need to carve up a Linux-internal ID space, do that dynamically. > > There is no need for this property. > > Better yet, don't create a Linux ID space for this. Everywhere we have > one, we want to get rid of it. Agreed. A completely opaque token / desc structure would prevent a lot of potential abuse and save us from painful breakage. Mark -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
