Hi Rob, > -----Original Message----- > From: Rob Herring [mailto:robh@xxxxxxxxxx] > Sent: Thursday, March 08, 2018 4:10 > To: Nipun Gupta <nipun.gupta@xxxxxxx> > Cc: will.deacon@xxxxxxx; robin.murphy@xxxxxxx; mark.rutland@xxxxxxx; > catalin.marinas@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; stuyoder@xxxxxxxxx; > Bharat Bhushan <bharat.bhushan@xxxxxxx>; gregkh@xxxxxxxxxxxxxxxxxxx; > joro@xxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > Leo Li <leoyang.li@xxxxxxx>; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; Laurentiu > Tudor <laurentiu.tudor@xxxxxxx>; shawnguo@xxxxxxxxxx; hch@xxxxxx; linux- > arm-kernel@xxxxxxxxxxxxxxxxxxx; m.szyprowski@xxxxxxxxxxx > Subject: Re: [PATCH 1/6] Docs: dt: add fsl-mc iommu-parent device-tree binding > > On Mon, Mar 05, 2018 at 07:59:21PM +0530, Nipun Gupta wrote: > > The existing IOMMU bindings cannot be used to specify the relationship > > between fsl-mc devices and IOMMUs. This patch adds a binding for > > mapping fsl-mc devices to IOMMUs, using a new iommu-parent property. > > > > Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx> > > --- > > .../devicetree/bindings/misc/fsl,qoriq-mc.txt | 31 > ++++++++++++++++++++++ > > 1 file changed, 31 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt > b/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt > > index 6611a7c..011c7d6 100644 > > --- a/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt > > +++ b/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt > > @@ -9,6 +9,24 @@ blocks that can be used to create functional hardware > objects/devices > > such as network interfaces, crypto accelerator instances, L2 switches, > > etc. > > > > +For an overview of the DPAA2 architecture and fsl-mc bus see: > > +drivers/staging/fsl-mc/README.txt > > + > > +As described in the above overview, all DPAA2 objects in a DPRC share the > > +same hardware "isolation context" and a 10-bit value called an ICID > > +(isolation context id) is expressed by the hardware to identify > > +the requester. > > + > > +The generic 'iommus' property is cannot be used to describe the relationship > > +between fsl-mc and IOMMUs, so an iommu-parent property is used to define > > +the same. > > Why not? It is just a link between 2 nodes. We have #iommu-cells as '1' i.e. iommu will have one stream ID configured for a device. Once USB and other devices start to use IOMMU we will also need this iommu-cells. When #iommu-cells is defined as '1' and we have 'iommus=<&smmu>' compilation reports warning about the mismatch. In fsl-mc bus case we do not have any stream id associated with the bus. As suggested by Robin, we can simply use the iommu-map property. > > > + > > +For generic IOMMU bindings, see > > +Documentation/devicetree/bindings/iommu/iommu.txt. > > + > > +For arm-smmu binding, see: > > +Documentation/devicetree/bindings/iommu/arm,smmu.txt. > > + > > Required properties: > > > > - compatible > > @@ -88,14 +106,27 @@ Sub-nodes: > > Value type: <phandle> > > Definition: Specifies the phandle to the PHY device node associated > > with the this dpmac. > > +Optional properties: > > + > > +- iommu-parent: Maps the devices on fsl-mc bus to an IOMMU. > > + The property specifies the IOMMU behind which the devices on > > + fsl-mc bus are residing. > > If you want a generic property, this should be documented in the common > binding. We can use the iommu-map property which is already documented. > > Couldn't you have more than 1 IOMMU upstream of a MC? There is no such device currently with which fsl-mc bus uses more than one iommu. Infact, our current systems have only single IOMMU :). Even in future if such devices are there then we can use iommu-map to specify more than one iommu with separate requester ID's (RID's). Thank you for review... Regards, Nipun > > > > > Example: > > > > + smmu: iommu@5000000 { > > + compatible = "arm,mmu-500"; > > + #iommu-cells = <1>; > > + stream-match-mask = <0x7C00>; > > + ... > > + }; > > + > > fsl_mc: fsl-mc@80c000000 { > > compatible = "fsl,qoriq-mc"; > > reg = <0x00000008 0x0c000000 0 0x40>, /* MC portal base */ > > <0x00000000 0x08340000 0 0x40000>; /* MC control reg */ > > msi-parent = <&its>; > > + iommu-parent = <&smmu>; > > #address-cells = <3>; > > #size-cells = <1>; > > > > -- > > 1.9.1 > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > > https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.infr > adead.org%2Fmailman%2Flistinfo%2Flinux-arm- > kernel&data=02%7C01%7Cnipun.gupta%40nxp.com%7Cf64b4fe9c5cf45ce8a9a > 08d5847c6919%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636560 > 592302736942&sdata=iOwv%2Fzd8UTLm7YCapDOWzrtd48VQeYY2vlufck7eYZI > %3D&reserved=0 -- 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
