On Tue, Sep 12, 2017 at 05:31:07PM +0530, Vivek Gautam wrote: > ARM MMU-500 implements a TBU (uTLB) for each connected master > besides a single TCU which controls and manages the address > translations. Each of these TBUs can either be in the same > power domain as the master, or they can have a independent > power switch. > This design addresses the challenges to control TBU power. > Adding child devices for each TBUs present in the configuration > lets us control the power and clocks to TLBs having individual > power domains. The device link between master devices (such as, > display, and GPU) and TBU devices ensures that the master takes > care of powering the smmu as long as it's available. > When the master is not available, the TBUs are identified with > sid and powered on. > > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> > --- > > - The idea behind this patch is to handle the distributed smmu > architectures, similar to MMU-500. > - Untested yet. > - There are still few instances where the correct tbu device has > to be referenced and thus powered on to handle TLB maintenance > operations. > > .../devicetree/bindings/iommu/arm,smmu.txt | 27 +++ > drivers/iommu/arm-smmu.c | 191 +++++++++++++++++++-- > 2 files changed, 205 insertions(+), 13 deletions(-) > > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > index d97a6bc8e608..7cf67e75022e 100644 > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > @@ -98,6 +98,18 @@ conditions. > accessed before master gets enabled and linked to its > SMMU. > > +- child nodes: ARM MMU-500 implements a TBU (page table cache or TLB) for > + each connected master besides a single TCU that controls > + and manages the address translations. > + Each of the child nodes represents a TBU that is attached to > + the master. This child node will have following property: > + > + - compatibe: must be "arm,mmu-500-tbu" for TBU child nodes of arm,mmu-500 > + smmu. > + - stream-id-range: array representing the starting stream id and the number > + of supported stream-ids. This gives information about > + the range of stream-ids that are supported by this TBU. Needs a vendor prefix. Also need to document reg property. What does reg represent? If just an index with no correlation to h/w numbering, then perhaps stream ids could be put into reg instead. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
