1ff3e077bSSimon GlassPCI with Driver Model 2ff3e077bSSimon Glass===================== 3ff3e077bSSimon Glass 4ff3e077bSSimon GlassHow busses are scanned 5ff3e077bSSimon Glass---------------------- 6ff3e077bSSimon Glass 7ff3e077bSSimon GlassAny config read will end up at pci_read_config(). This uses 8ff3e077bSSimon Glassuclass_get_device_by_seq() to get the PCI bus for a particular bus number. 9ff3e077bSSimon GlassBus number 0 will need to be requested first, and the alias in the device 10ff3e077bSSimon Glasstree file will point to the correct device: 11ff3e077bSSimon Glass 12ff3e077bSSimon Glass 13ff3e077bSSimon Glass aliases { 14ff3e077bSSimon Glass pci0 = &pci; 15ff3e077bSSimon Glass }; 16ff3e077bSSimon Glass 17ff3e077bSSimon Glass pci: pci-controller { 18ff3e077bSSimon Glass compatible = "sandbox,pci"; 19ff3e077bSSimon Glass ... 20ff3e077bSSimon Glass }; 21ff3e077bSSimon Glass 22ff3e077bSSimon Glass 23ff3e077bSSimon GlassIf there is no alias the devices will be numbered sequentially in the device 24ff3e077bSSimon Glasstree. 25ff3e077bSSimon Glass 26947eb439SBin MengThe call to uclass_get_device() will cause the PCI bus to be probed. 27ff3e077bSSimon GlassThis does a scan of the bus to locate available devices. These devices are 28ff3e077bSSimon Glassbound to their appropriate driver if available. If there is no driver, then 29ff3e077bSSimon Glassthey are bound to a generic PCI driver which does nothing. 30ff3e077bSSimon Glass 31ff3e077bSSimon GlassAfter probing a bus, the available devices will appear in the device tree 32ff3e077bSSimon Glassunder that bus. 33ff3e077bSSimon Glass 34ff3e077bSSimon GlassNote that this is all done on a lazy basis, as needed, so until something is 35947eb439SBin Mengtouched on PCI (eg: a call to pci_find_devices()) it will not be probed. 36ff3e077bSSimon Glass 37*92ed9865SMarek VasutPCI devices can appear in the flattened device tree. If they do, their node 38*92ed9865SMarek Vasutoften contains extra information which cannot be derived from the PCI IDs or 39*92ed9865SMarek VasutPCI class of the device. Each PCI device node must have a <reg> property, as 40*92ed9865SMarek Vasutdefined by the IEEE Std 1275-1994 PCI bus binding document v2.1. Compatible 41*92ed9865SMarek Vasutstring list is optional and generally not needed, since PCI is discoverable 42*92ed9865SMarek Vasutbus, albeit there are justified exceptions. If the compatible string is 43*92ed9865SMarek Vasutpresent, matching on it takes precedence over PCI IDs and PCI classes. 44*92ed9865SMarek Vasut 45*92ed9865SMarek VasutNote we must describe PCI devices with the same bus hierarchy as the 46f4b5db7cSBin Menghardware, otherwise driver model cannot detect the correct parent/children 47f4b5db7cSBin Mengrelationship during PCI bus enumeration thus PCI devices won't be bound to 48f4b5db7cSBin Mengtheir drivers accordingly. A working example like below: 49f4b5db7cSBin Meng 50f4b5db7cSBin Meng pci { 51f4b5db7cSBin Meng #address-cells = <3>; 52f4b5db7cSBin Meng #size-cells = <2>; 53f4b5db7cSBin Meng compatible = "pci-x86"; 54f4b5db7cSBin Meng u-boot,dm-pre-reloc; 55f4b5db7cSBin Meng ranges = <0x02000000 0x0 0x40000000 0x40000000 0 0x80000000 56f4b5db7cSBin Meng 0x42000000 0x0 0xc0000000 0xc0000000 0 0x20000000 57f4b5db7cSBin Meng 0x01000000 0x0 0x2000 0x2000 0 0xe000>; 58f4b5db7cSBin Meng 59f4b5db7cSBin Meng pcie@17,0 { 60f4b5db7cSBin Meng #address-cells = <3>; 61f4b5db7cSBin Meng #size-cells = <2>; 62f4b5db7cSBin Meng compatible = "pci-bridge"; 63f4b5db7cSBin Meng u-boot,dm-pre-reloc; 64f4b5db7cSBin Meng reg = <0x0000b800 0x0 0x0 0x0 0x0>; 65f4b5db7cSBin Meng 66f4b5db7cSBin Meng topcliff@0,0 { 67f4b5db7cSBin Meng #address-cells = <3>; 68f4b5db7cSBin Meng #size-cells = <2>; 69f4b5db7cSBin Meng compatible = "pci-bridge"; 70f4b5db7cSBin Meng u-boot,dm-pre-reloc; 71f4b5db7cSBin Meng reg = <0x00010000 0x0 0x0 0x0 0x0>; 72f4b5db7cSBin Meng 73f4b5db7cSBin Meng pciuart0: uart@a,1 { 74f4b5db7cSBin Meng compatible = "pci8086,8811.00", 75f4b5db7cSBin Meng "pci8086,8811", 76f4b5db7cSBin Meng "pciclass,070002", 77f4b5db7cSBin Meng "pciclass,0700", 78f4b5db7cSBin Meng "x86-uart"; 79f4b5db7cSBin Meng u-boot,dm-pre-reloc; 80f4b5db7cSBin Meng reg = <0x00025100 0x0 0x0 0x0 0x0 81f4b5db7cSBin Meng 0x01025110 0x0 0x0 0x0 0x0>; 82f4b5db7cSBin Meng ...... 83f4b5db7cSBin Meng }; 84f4b5db7cSBin Meng 85f4b5db7cSBin Meng ...... 86f4b5db7cSBin Meng }; 87f4b5db7cSBin Meng }; 88f4b5db7cSBin Meng 89f4b5db7cSBin Meng ...... 90f4b5db7cSBin Meng }; 91f4b5db7cSBin Meng 92f4b5db7cSBin MengIn this example, the root PCI bus node is the "/pci" which matches "pci-x86" 93f4b5db7cSBin Mengdriver. It has a subnode "pcie@17,0" with driver "pci-bridge". "pcie@17,0" 94f4b5db7cSBin Mengalso has subnode "topcliff@0,0" which is a "pci-bridge" too. Under that bridge, 95f4b5db7cSBin Menga PCI UART device "uart@a,1" is described. This exactly reflects the hardware 96f4b5db7cSBin Mengbus hierarchy: on the root PCI bus, there is a PCIe root port which connects 97f4b5db7cSBin Mengto a downstream device Topcliff chipset. Inside Topcliff chipset, it has a 98f4b5db7cSBin MengPCIe-to-PCI bridge and all the chipset integrated devices like the PCI UART 99f4b5db7cSBin Mengdevice are on the PCI bus. Like other devices in the device tree, if we want 100f4b5db7cSBin Mengto bind PCI devices before relocation, "u-boot,dm-pre-reloc" must be declared 101f4b5db7cSBin Mengin each of these nodes. 102f4b5db7cSBin Meng 103f4b5db7cSBin MengIf PCI devices are not listed in the device tree, U_BOOT_PCI_DEVICE can be used 104f4b5db7cSBin Mengto specify the driver to use for the device. The device tree takes precedence 105f4b5db7cSBin Mengover U_BOOT_PCI_DEVICE. Plese note with U_BOOT_PCI_DEVICE, only drivers with 106f4b5db7cSBin MengDM_FLAG_PRE_RELOC will be bound before relocation. If neither device tree nor 107f4b5db7cSBin MengU_BOOT_PCI_DEVICE is provided, the built-in driver (either pci_bridge_drv or 108f4b5db7cSBin Mengpci_generic_drv) will be used. 109ff3e077bSSimon Glass 110ff3e077bSSimon Glass 111ff3e077bSSimon GlassSandbox 112ff3e077bSSimon Glass------- 113ff3e077bSSimon Glass 114ff3e077bSSimon GlassWith sandbox we need a device emulator for each device on the bus since there 115ff3e077bSSimon Glassis no real PCI bus. This works by looking in the device tree node for a 116ff3e077bSSimon Glassdriver. For example: 117ff3e077bSSimon Glass 118ff3e077bSSimon Glass 119ff3e077bSSimon Glass pci@1f,0 { 120ff3e077bSSimon Glass compatible = "pci-generic"; 121ff3e077bSSimon Glass reg = <0xf800 0 0 0 0>; 122ff3e077bSSimon Glass emul@1f,0 { 123ff3e077bSSimon Glass compatible = "sandbox,swap-case"; 124ff3e077bSSimon Glass }; 125ff3e077bSSimon Glass }; 126ff3e077bSSimon Glass 127ff3e077bSSimon GlassThis means that there is a 'sandbox,swap-case' driver at that bus position. 128ff3e077bSSimon GlassNote that the first cell in the 'reg' value is the bus/device/function. See 129ff3e077bSSimon GlassPCI_BDF() for the encoding (it is also specified in the IEEE Std 1275-1994 130ff3e077bSSimon GlassPCI bus binding document, v2.1) 131ff3e077bSSimon Glass 132ff3e077bSSimon GlassWhen this bus is scanned we will end up with something like this: 133ff3e077bSSimon Glass 134ff3e077bSSimon Glass`- * pci-controller @ 05c660c8, 0 135ff3e077bSSimon Glass `- pci@1f,0 @ 05c661c8, 63488 136ff3e077bSSimon Glass `- emul@1f,0 @ 05c662c8 137ff3e077bSSimon Glass 138ff3e077bSSimon GlassWhen accesses go to the pci@1f,0 device they are forwarded to its child, the 139ff3e077bSSimon Glassemulator. 1404345998aSBin Meng 1414345998aSBin MengThe sandbox PCI drivers also support dynamic driver binding, allowing device 1424345998aSBin Mengdriver to declare the driver binding information via U_BOOT_PCI_DEVICE(), 1434345998aSBin Mengeliminating the need to provide any device tree node under the host controller 1444345998aSBin Mengnode. It is required a "sandbox,dev-info" property must be provided in the 1454345998aSBin Menghost controller node for this functionality to work. 1464345998aSBin Meng 1474345998aSBin Meng pci1: pci-controller1 { 1484345998aSBin Meng compatible = "sandbox,pci"; 1494345998aSBin Meng ... 1504345998aSBin Meng sandbox,dev-info = <0x08 0x00 0x1234 0x5678 1514345998aSBin Meng 0x0c 0x00 0x1234 0x5678>; 1524345998aSBin Meng }; 1534345998aSBin Meng 1544345998aSBin MengThe "sandbox,dev-info" property specifies all dynamic PCI devices on this bus. 1554345998aSBin MengEach dynamic PCI device is encoded as 4 cells a group. The first and second 1564345998aSBin Mengcells are PCI device number and function number respectively. The third and 1574345998aSBin Mengfourth cells are PCI vendor ID and device ID respectively. 1584345998aSBin Meng 1594345998aSBin MengWhen this bus is scanned we will end up with something like this: 1604345998aSBin Meng 1614345998aSBin Meng pci [ + ] pci_sandbo |-- pci-controller1 1624345998aSBin Meng pci_emul [ ] sandbox_sw | |-- sandbox_swap_case_emul 1634345998aSBin Meng pci_emul [ ] sandbox_sw | `-- sandbox_swap_case_emul 1644345998aSBin Meng 1654345998aSBin MengNote the difference from the statically declared device nodes is that the 1664345998aSBin Mengdevice is directly attached to the host controller, instead of via a container 1674345998aSBin Mengdevice like pci@1f,0. 168