On 23/07/15 17:52, Mark Rutland wrote: > 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: > + > + * 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. > + > +- 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. Right, this is where I'd expect some details about #msi-cells. Is it meant to be ignored? The lack of symmetry between the PCI and non-PCI use cases feels a bit inelegant (not to mention that it precludes having an unified parser for both cases). This otherwise looks good to me. Thanks, M. -- Jazz is not dead. It just smells funny... -- 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
