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Diffstat (limited to 'Documentation/devicetree/bindings/pci/host-generic-pci.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/pci/host-generic-pci.txt | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/pci/host-generic-pci.txt b/Documentation/devicetree/bindings/pci/host-generic-pci.txt new file mode 100644 index 000000000..3f1d3fca6 --- /dev/null +++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt @@ -0,0 +1,101 @@ +* Generic PCI host controller + +Firmware-initialised PCI host controllers and PCI emulations, such as the +virtio-pci implementations found in kvmtool and other para-virtualised +systems, do not require driver support for complexities such as regulator +and clock management. In fact, the controller may not even require the +configuration of a control interface by the operating system, instead +presenting a set of fixed windows describing a subset of IO, Memory and +Configuration Spaces. + +Such a controller can be described purely in terms of the standardized device +tree bindings communicated in pci.txt: + + +Properties of the host controller node: + +- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic" + depending on the layout of configuration space (CAM vs + ECAM respectively). + +- device_type : Must be "pci". + +- ranges : As described in IEEE Std 1275-1994, but must provide + at least a definition of non-prefetchable memory. One + or both of prefetchable Memory and IO Space may also + be provided. + +- bus-range : Optional property (also described in IEEE Std 1275-1994) + to indicate the range of bus numbers for this controller. + If absent, defaults to <0 255> (i.e. all buses). + +- #address-cells : Must be 3. + +- #size-cells : Must be 2. + +- reg : The Configuration Space base address and size, as accessed + from the parent bus. The base address corresponds to + the first bus in the "bus-range" property. If no + "bus-range" is specified, this will be bus 0 (the default). + +Properties of the /chosen node: + +- linux,pci-probe-only + : Optional property which takes a single-cell argument. + If '0', then Linux will assign devices in its usual manner, + otherwise it will not try to assign devices and instead use + them as they are configured already. + +Configuration Space is assumed to be memory-mapped (as opposed to being +accessed via an ioport) and laid out with a direct correspondence to the +geography of a PCI bus address by concatenating the various components to +form an offset. + +For CAM, this 24-bit offset is: + + cfg_offset(bus, device, function, register) = + bus << 16 | device << 11 | function << 8 | register + +Whilst ECAM extends this by 4 bits to accommodate 4k of function space: + + cfg_offset(bus, device, function, register) = + bus << 20 | device << 15 | function << 12 | register + +Interrupt mapping is exactly as described in `Open Firmware Recommended +Practice: Interrupt Mapping' and requires the following properties: + +- #interrupt-cells : Must be 1 + +- interrupt-map : <see aforementioned specification> + +- interrupt-map-mask : <see aforementioned specification> + + +Example: + +pci { + compatible = "pci-host-cam-generic" + device_type = "pci"; + #address-cells = <3>; + #size-cells = <2>; + bus-range = <0x0 0x1>; + + // CPU_PHYSICAL(2) SIZE(2) + reg = <0x0 0x40000000 0x0 0x1000000>; + + // BUS_ADDRESS(3) CPU_PHYSICAL(2) SIZE(2) + ranges = <0x01000000 0x0 0x01000000 0x0 0x01000000 0x0 0x00010000>, + <0x02000000 0x0 0x41000000 0x0 0x41000000 0x0 0x3f000000>; + + + #interrupt-cells = <0x1>; + + // PCI_DEVICE(3) INT#(1) CONTROLLER(PHANDLE) CONTROLLER_DATA(3) + interrupt-map = < 0x0 0x0 0x0 0x1 &gic 0x0 0x4 0x1 + 0x800 0x0 0x0 0x1 &gic 0x0 0x5 0x1 + 0x1000 0x0 0x0 0x1 &gic 0x0 0x6 0x1 + 0x1800 0x0 0x0 0x1 &gic 0x0 0x7 0x1>; + + // PCI_DEVICE(3) INT#(1) + interrupt-map-mask = <0xf800 0x0 0x0 0x7>; +} |