Hi Mark Thanks for the patch. Please find my comment inline. Regards Varun > -----Original Message----- > From: iommu-bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx [mailto:iommu- > bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Mark Rutland > Sent: Thursday, July 23, 2015 10:23 PM > To: devicetree@xxxxxxxxxxxxxxx > Cc: Mark Rutland; lorenzo.pieralisi@xxxxxxx; arnd@xxxxxxxx; > marc.zyngier@xxxxxxx; will.deacon@xxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; ddaney@xxxxxxxxxxxxxxxxxx; iommu@lists.linux- > foundation.org; tirumalesh.chalamarla@xxxxxxxxxxxxxxxxxx; > laurent.pinchart@xxxxxxxxxxxxxxxx; thunder.leizhen@xxxxxxxxxx; > treding@xxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > majun258@xxxxxxxxxx > Subject: [PATCH 2/3] Docs: dt: Add PCI MSI map bindings > > Currently msi-parent is used by a few bindings to describe the relationship > between a PCI root complex and a single MSI controller, but this property > does not have a generic binding document. > > Additionally, msi-parent is insufficient to describe more complex > relationships between MSI controllers and devices under a root complex, > where devices may be able to target multiple MSI controllers, or where MSI > controllers use (non-probeable) sideband information to distinguish devices. > > This patch adds a generic binding for mapping PCI devices to MSI controllers. > This document covers msi-parent, and a new msi-map property (specific to > PCI*) which may be used to map devices (identified by their Requester ID) to > sideband data for each MSI controller that they may target. > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > --- > Documentation/devicetree/bindings/pci/pci-msi.txt | 220 > ++++++++++++++++++++++ > 1 file changed, 220 insertions(+) > create mode 100644 Documentation/devicetree/bindings/pci/pci-msi.txt > > diff --git a/Documentation/devicetree/bindings/pci/pci-msi.txt > b/Documentation/devicetree/bindings/pci/pci-msi.txt > new file mode 100644 > index 0000000..9b3cc81 > --- /dev/null > +++ b/Documentation/devicetree/bindings/pci/pci-msi.txt > @@ -0,0 +1,220 @@ > +This document describes the generic device tree binding for describing > +the relationship between PCI devices and MSI controllers. > + > +Each PCI device under a root complex is uniquely identified by its > +Requester ID (AKA RID). A Requester ID is a triplet of a Bus number, > +Device number, and Function number. > + > +For the purpose of this document, when treated as a numeric value, a > +RID is formatted such that: > + > +* Bits [15:8] are the Bus number. > +* Bits [7:3] are the Device number. > +* Bits [2:0] are the Function number. > +* Any other bits required for padding must be zero. > + > +MSIs may be distinguished in part through the use of sideband data > +accompanying writes. In the case of PCI devices, this sideband data may > +be derived from the Requester ID. A mechanism is required to associate > +a device with both the MSI controllers it can address, and the sideband > +data that will be associated with its writes to those controllers. > + > +For generic MSI bindings, see > +Documentation/devicetree/bindings/interrupt-controller/msi.txt. > + > + > +PCI root complex > +================ > + > +Optional properties > +------------------- > + > +- msi-map: Maps a Requester ID to an MSI controller and associated > + msi-specifier data. The property is an arbitrary number of tuples of > + (rid-base,msi-controller,msi-base,length), where: [varun] How would we account for hot plug PCI devices and SR-IOV use cases, with the rid base and length? How do we take in to account for a PCIe bridge, while setting up the requestor ID base and length? > + > + * rid-base is a single cell describing the first RID matched by the entry. > + > + * msi-controller is a single phandle to an MSI controller > + > + * msi-base is an msi-specifier describing the msi-specifier produced for the > + first RID matched by the entry. > + > + * length is a single cell describing how many consecutive RIDs are matched > + following the rid-base. > + > + Any RID r in the interval [rid-base, rid-base + length) is associated > + with the listed msi-controller, with the msi-specifier (r - rid-base + msi- > base). > + > +- msi-map-mask: A mask to be applied to each Requester ID prior to > +being mapped > + to an msi-specifier per the msi-map property. > + [varun] Can you please elaborate on a use case, where this would help. > +- msi-parent: Describes the MSI parent of the root complex itself. > +Where > + the root complex and MSI controller do not pass sideband data with > +MSI > + writes, this property may be used to describe the MSI controller(s) > + used by PCI devices under the root complex, if defined as such in the > + binding for the root complex. > + > + > +Example (1) > +=========== > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + msi: msi-controller@a { > + reg = <0xa 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + pci: pci@f { > + reg = <0xf 0x1>; > + compatible = "vendor,pcie-root-complex"; > + device_type = "pci"; > + > + /* > + * The sideband data provided to the MSI controller is > + * the RID, identity-mapped. > + */ > + msi-map = <0x0 &msi_a 0x0 0x10000>, > + }; > +}; > + > + > +Example (2) > +=========== > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + msi: msi-controller@a { > + reg = <0xa 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + pci: pci@f { > + reg = <0xf 0x1>; > + compatible = "vendor,pcie-root-complex"; > + device_type = "pci"; > + > + /* > + * The sideband data provided to the MSI controller is > + * the RID, masked to only the device and function bits. > + */ > + msi-map = <0x0 &msi_a 0x0 0x100>, > + msi-map-mask = <0xff> > + }; > +}; > + > + > +Example (3) > +=========== > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + msi: msi-controller@a { > + reg = <0xa 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + pci: pci@f { > + reg = <0xf 0x1>; > + compatible = "vendor,pcie-root-complex"; > + device_type = "pci"; > + > + /* > + * The sideband data provided to the MSI controller is > + * the RID, but the high bit of the bus number is > + * ignored. > + */ > + msi-map = <0x0000 &msi 0x0000 0x8000>, > + <0x8000 &msi 0x0000 0x8000>; > + }; > +}; > + > + > +Example (4) > +=========== > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + msi: msi-controller@a { > + reg = <0xa 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + pci: pci@f { > + reg = <0xf 0x1>; > + compatible = "vendor,pcie-root-complex"; > + device_type = "pci"; > + > + /* > + * The sideband data provided to the MSI controller is > + * the RID, but the high bit of the bus number is > + * negated. > + */ > + msi-map = <0x0000 &msi 0x8000 0x8000>, > + <0x8000 &msi 0x0000 0x8000>; > + }; > +}; > + > + > +Example (5) > +=========== > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + msi_a: msi-controller@a { > + reg = <0xa 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + msi_b: msi-controller@b { > + reg = <0xb 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + msi_c: msi-controller@c { > + reg = <0xc 0x1>; > + compatible = "vendor,some-controller"; > + msi-controller; > + #msi-cells = <1>; > + }; > + > + pci: pci@c { > + reg = <0xf 0x1>; > + compatible = "vendor,pcie-root-complex"; > + device_type = "pci"; > + > + /* > + * The sideband data provided to MSI controller a is the > + * RID, but the high bit of the bus number is negated. > + * The sideband data provided to MSI controller b is the > + * RID, identity-mapped. > + * MSI controller c is not addressable. > + */ > + msi-map = <0x0000 &msi_a 0x8000 0x08000>, > + <0x8000 &msi_a 0x0000 0x08000>, > + <0x0000 &msi_b 0x0000 0x10000>; > + }; > +}; > -- > 1.9.1 > > _______________________________________________ > iommu mailing list > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/iommu -- 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
