Documentation/devicetree/bindings/pci/host-generic-pci.txt

   1 * Generic PCI host controller
   2
   3 Firmware-initialised PCI host controllers and PCI emulations, such as the
   4 virtio-pci implementations found in kvmtool and other para-virtualised
   5 systems, do not require driver support for complexities such as regulator
   6 and clock management. In fact, the controller may not even require the
   7 configuration of a control interface by the operating system, instead
   8 presenting a set of fixed windows describing a subset of IO, Memory and
   9 Configuration Spaces.
  10
  11 Such a controller can be described purely in terms of the standardized device
  12 tree bindings communicated in pci.txt:
  13
  14
  15 Properties of the host controller node:
  16
  17 - compatible     : Must be "pci-host-cam-generic" or "pci-host-ecam-generic"
  18                    depending on the layout of configuration space (CAM vs
  19                    ECAM respectively).
  20
  21 - device_type    : Must be "pci".
  22
  23 - ranges         : As described in IEEE Std 1275-1994, but must provide
  24                    at least a definition of non-prefetchable memory. One
  25                    or both of prefetchable Memory and IO Space may also
  26                    be provided.
  27
  28 - bus-range      : Optional property (also described in IEEE Std 1275-1994)
  29                    to indicate the range of bus numbers for this controller.
  30                    If absent, defaults to <0 255> (i.e. all buses).
  31
  32 - #address-cells : Must be 3.
  33
  34 - #size-cells    : Must be 2.
  35
  36 - reg            : The Configuration Space base address and size, as accessed
  37                    from the parent bus.  The base address corresponds to
  38                    the first bus in the "bus-range" property.  If no
  39                    "bus-range" is specified, this will be bus 0 (the default).
  40
  41 Properties of the /chosen node:
  42
  43 - linux,pci-probe-only
  44                  : Optional property which takes a single-cell argument.
  45                    If '0', then Linux will assign devices in its usual manner,
  46                    otherwise it will not try to assign devices and instead use
  47                    them as they are configured already.
  48
  49 Configuration Space is assumed to be memory-mapped (as opposed to being
  50 accessed via an ioport) and laid out with a direct correspondence to the
  51 geography of a PCI bus address by concatenating the various components to
  52 form an offset.
  53
  54 For CAM, this 24-bit offset is:
  55
  56         cfg_offset(bus, device, function, register) =
  57                    bus << 16 | device << 11 | function << 8 | register
  58
  59 Whilst ECAM extends this by 4 bits to accommodate 4k of function space:
  60
  61         cfg_offset(bus, device, function, register) =
  62                    bus << 20 | device << 15 | function << 12 | register
  63
  64 Interrupt mapping is exactly as described in `Open Firmware Recommended
  65 Practice: Interrupt Mapping' and requires the following properties:
  66
  67 - #interrupt-cells   : Must be 1
  68
  69 - interrupt-map      : <see aforementioned specification>
  70
  71 - interrupt-map-mask : <see aforementioned specification>
  72
  73
  74 Example:
  75
  76 pci {
  77     compatible = "pci-host-cam-generic"
  78     device_type = "pci";
  79     #address-cells = <3>;
  80     #size-cells = <2>;
  81     bus-range = <0x0 0x1>;
  82
  83     // CPU_PHYSICAL(2)  SIZE(2)
  84     reg = <0x0 0x40000000  0x0 0x1000000>;
  85
  86     // BUS_ADDRESS(3)  CPU_PHYSICAL(2)  SIZE(2)
  87     ranges = <0x01000000 0x0 0x01000000  0x0 0x01000000  0x0 0x00010000>,
  88              <0x02000000 0x0 0x41000000  0x0 0x41000000  0x0 0x3f000000>;
  89
  90
  91     #interrupt-cells = <0x1>;
  92
  93     // PCI_DEVICE(3)  INT#(1)  CONTROLLER(PHANDLE)  CONTROLLER_DATA(3)
  94     interrupt-map = <  0x0 0x0 0x0  0x1  &gic  0x0 0x4 0x1
  95                      0x800 0x0 0x0  0x1  &gic  0x0 0x5 0x1
  96                     0x1000 0x0 0x0  0x1  &gic  0x0 0x6 0x1
  97                     0x1800 0x0 0x0  0x1  &gic  0x0 0x7 0x1>;
  98
  99     // PCI_DEVICE(3)  INT#(1)
 100     interrupt-map-mask = <0xf800 0x0 0x0  0x7>;
 101 }