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PCI - how does it work at the hardware level? http://www.fpga4fun.com/PCI.html How does PCI worked in Linux? From the documentation Documentation/PCI/pci.txt - here are the setup/teardown details: (how to write a PCI drivers?) Once the driver knows about a PCI device and takes ownership, the driver generally needs to perform the following initialization: Enable the device Request MMIO/IOP resources Set the DMA mask size (for both coherent and streaming DMA) Allocate and initialize shared control data (pci_allocate_coherent()) Access device configuration space (if needed) Register IRQ handler (request_irq()) Initialize non-PCI (i.e. LAN/SCSI/etc parts of the chip) Enable DMA/processing engines When done using the device, and perhaps the module needs to be unloaded, the driver needs to take the follow steps: Disable the device from generating IRQs Release the IRQ (free_irq()) Stop all DMA activity Release DMA buffers (both streaming and coherent) Unregister from other subsystems (e.g. scsi or netdev) Release MMIO/IOP resources Disable the device On the other hand, how to write a userspace PCI drivers: http://lwn.net/Articles/197523/ What are the commands to control the PCI? Inside the linux/pci_regs.h: /* * Under PCI, each device has 256 bytes of configuration address space, * of which the first 64 bytes are standardized as follows: */ #define PCI_VENDOR_ID 0x00 /* 16 bits */ #define PCI_DEVICE_ID 0x02 /* 16 bits */ #define PCI_COMMAND 0x04 /* 16 bits */ #define PCI_COMMAND_IO 0x1 /* Enable response in I/O space */ #define PCI_COMMAND_MEMORY 0x2 /* Enable response in Memory space */ #define PCI_COMMAND_MASTER 0x4 /* Enable bus mastering */ #define PCI_COMMAND_SPECIAL 0x8 /* Enable response to special cycles */ #define PCI_COMMAND_INVALIDATE 0x10 /* Use memory write and invalidate */ #define PCI_COMMAND_VGA_PALETTE 0x20 /* Enable palette snooping */ #define PCI_COMMAND_PARITY 0x40 /* Enable parity checking */ #define PCI_COMMAND_WAIT 0x80 /* Enable address/data stepping */ #define PCI_COMMAND_SERR 0x100 /* Enable SERR */ #define PCI_COMMAND_FAST_BACK 0x200 /* Enable back-to-back writes */ #define PCI_COMMAND_INTX_DISABLE 0x400 /* INTx Emulation Disable */ #define PCI_STATUS 0x06 /* 16 bits */ #define PCI_STATUS_CAP_LIST 0x10 /* Support Capability List */ #define PCI_STATUS_66MHZ 0x20 /* Support 66 Mhz PCI 2.1 bus */ #define PCI_STATUS_UDF 0x40 /* Support User Definable Features [obsolete] */ #define PCI_STATUS_FAST_BACK 0x80 /* Accept fast-back to back */ #define PCI_STATUS_PARITY 0x100 /* Detected parity error */ #define PCI_STATUS_DEVSEL_MASK 0x600 /* DEVSEL timing */ #define PCI_STATUS_DEVSEL_FAST 0x000 #define PCI_STATUS_DEVSEL_MEDIUM 0x200 #define PCI_STATUS_DEVSEL_SLOW 0x400 #define PCI_STATUS_SIG_TARGET_ABORT 0x800 /* Set on target abort */ #define PCI_STATUS_REC_TARGET_ABORT 0x1000 /* Master ack of " */ #define PCI_STATUS_REC_MASTER_ABORT 0x2000 /* Set on master abort */ #define PCI_STATUS_SIG_SYSTEM_ERROR 0x4000 /* Set when we drive SERR */ #define PCI_STATUS_DETECTED_PARITY 0x8000 /* Set on parity error */ #define PCI_CLASS_REVISION 0x08 /* High 24 bits are class, low 8 revision */ #define PCI_REVISION_ID 0x08 /* Revision ID */ #define PCI_CLASS_PROG 0x09 /* Reg. Level Programming Interface */ #define PCI_CLASS_DEVICE 0x0a /* Device class */ #define PCI_CACHE_LINE_SIZE 0x0c /* 8 bits */ #define PCI_LATENCY_TIMER 0x0d /* 8 bits */ #define PCI_HEADER_TYPE 0x0e /* 8 bits */ #define PCI_HEADER_TYPE_NORMAL 0 #define PCI_HEADER_TYPE_BRIDGE 1 #define PCI_HEADER_TYPE_CARDBUS 2 #define PCI_BIST 0x0f /* 8 bits */ #define PCI_BIST_CODE_MASK 0x0f /* Return result */ #define PCI_BIST_START 0x40 /* 1 to start BIST, 2 secs or less */ #define PCI_BIST_CAPABLE 0x80 /* 1 if BIST capable */ /* * Base addresses specify locations in memory or I/O space. * Decoded size can be determined by writing a value of * 0xffffffff to the register, and reading it back. Only * 1 bits are decoded. */ #define PCI_BASE_ADDRESS_0 0x10 /* 32 bits */ #define PCI_BASE_ADDRESS_1 0x14 /* 32 bits [htype 0,1 only] */ #define PCI_BASE_ADDRESS_2 0x18 /* 32 bits [htype 0 only] */ #define PCI_BASE_ADDRESS_3 0x1c /* 32 bits */ #define PCI_BASE_ADDRESS_4 0x20 /* 32 bits */ #define PCI_BASE_ADDRESS_5 0x24 /* 32 bits */ #define PCI_BASE_ADDRESS_SPACE 0x01 /* 0 = memory, 1 = I/O */ #define PCI_BASE_ADDRESS_SPACE_IO 0x01 #define PCI_BASE_ADDRESS_SPACE_MEMORY 0x00 #define PCI_BASE_ADDRESS_MEM_TYPE_MASK 0x06 #define PCI_BASE_ADDRESS_MEM_TYPE_32 0x00 /* 32 bit address */ #define PCI_BASE_ADDRESS_MEM_TYPE_1M 0x02 /* Below 1M [obsolete] */ #define PCI_BASE_ADDRESS_MEM_TYPE_64 0x04 /* 64 bit address */ #define PCI_BASE_ADDRESS_MEM_PREFETCH 0x08 /* prefetchable? */ #define PCI_BASE_ADDRESS_MEM_MASK (~0x0fUL) #define PCI_BASE_ADDRESS_IO_MASK (~0x03UL) /* bit 1 is reserved if address_space = 1 */ /* Capability lists */ #define PCI_CAP_LIST_ID 0 /* Capability ID */ #define PCI_CAP_ID_PM 0x01 /* Power Management */ #define PCI_CAP_ID_AGP 0x02 /* Accelerated Graphics Port */ #define PCI_CAP_ID_VPD 0x03 /* Vital Product Data */ #define PCI_CAP_ID_SLOTID 0x04 /* Slot Identification */ #define PCI_CAP_ID_MSI 0x05 /* Message Signalled Interrupts */ #define PCI_CAP_ID_CHSWP 0x06 /* CompactPCI HotSwap */ #define PCI_CAP_ID_PCIX 0x07 /* PCI-X */ #define PCI_CAP_ID_HT 0x08 /* HyperTransport */ #define PCI_CAP_ID_VNDR 0x09 /* Vendor specific */ #define PCI_CAP_ID_DBG 0x0A /* Debug port */ #define PCI_CAP_ID_CCRC 0x0B /* CompactPCI Central Resource Control */ #define PCI_CAP_ID_SHPC 0x0C /* PCI Standard Hot-Plug Controller */ #define PCI_CAP_ID_SSVID 0x0D /* Bridge subsystem vendor/device ID */ #define PCI_CAP_ID_AGP3 0x0E /* AGP Target PCI-PCI bridge */ #define PCI_CAP_ID_EXP 0x10 /* PCI Express */ #define PCI_CAP_ID_MSIX 0x11 /* MSI-X */ #define PCI_CAP_LIST_NEXT 1 /* Next capability in the list */ #define PCI_CAP_FLAGS 2 /* Capability defined flags (16 bits) */ #define PCI_CAP_SIZEOF 4 /* Power Management Registers */ /* Power Management Registers */ #define PCI_PM_PMC 2 /* PM Capabilities Register */ #define PCI_PM_CAP_VER_MASK 0x0007 /* Version */ #define PCI_PM_CAP_PME_CLOCK 0x0008 /* PME clock required */ #define PCI_PM_CAP_RESERVED 0x0010 /* Reserved field */ #define PCI_PM_CAP_DSI 0x0020 /* Device specific initialization */ #define PCI_PM_CAP_AUX_POWER 0x01C0 /* Auxilliary power support mask */ #define PCI_PM_CAP_D1 0x0200 /* D1 power state support */ #define PCI_PM_CAP_D2 0x0400 /* D2 power state support */ #define PCI_PM_CAP_PME 0x0800 /* PME pin supported */ #define PCI_PM_CAP_PME_MASK 0xF800 /* PME Mask of all supported states */ #define PCI_PM_CAP_PME_D0 0x0800 /* PME# from D0 */ #define PCI_PM_CAP_PME_D1 0x1000 /* PME# from D1 */ #define PCI_PM_CAP_PME_D2 0x2000 /* PME# from D2 */ #define PCI_PM_CAP_PME_D3 0x4000 /* PME# from D3 (hot) */ #define PCI_PM_CAP_PME_D3cold 0x8000 /* PME# from D3 (cold) */ #define PCI_PM_CAP_PME_SHIFT 11 /* Start of the PME Mask in PMC */ #define PCI_PM_CTRL 4 /* PM control and status register */ #define PCI_PM_CTRL_STATE_MASK 0x0003 /* Current power state (D0 to D3) */ #define PCI_PM_CTRL_NO_SOFT_RESET 0x0008 /* No reset for D3hot->D0 */ #define PCI_PM_CTRL_PME_ENABLE 0x0100 /* PME pin enable */ #define PCI_PM_CTRL_DATA_SEL_MASK 0x1e00 /* Data select (??) */ #define PCI_PM_CTRL_DATA_SCALE_MASK 0x6000 /* Data scale (??) */ #define PCI_PM_CTRL_PME_STATUS 0x8000 /* PME pin status */ #define PCI_PM_PPB_EXTENSIONS 6 /* PPB support extensions (??) */ #define PCI_PM_PPB_B2_B3 0x40 /* Stop clock when in D3hot (??) */ #define PCI_PM_BPCC_ENABLE 0x80 /* Bus power/clock control enable (??) */ #define PCI_PM_DATA_REGISTER 7 /* (??) */ #define PCI_PM_SIZEOF 8 /* AGP registers */ #define PCI_AGP_VERSION 2 /* BCD version number */ #define PCI_AGP_RFU 3 /* Rest of capability flags */ #define PCI_AGP_STATUS 4 /* Status register */ #define PCI_AGP_STATUS_RQ_MASK 0xff000000 /* Maximum number of requests - 1 */ #define PCI_AGP_STATUS_SBA 0x0200 /* Sideband addressing supported */ #define PCI_AGP_STATUS_64BIT 0x0020 /* 64-bit addressing supported */ #define PCI_AGP_STATUS_FW 0x0010 /* FW transfers supported */ #define PCI_AGP_STATUS_RATE4 0x0004 /* 4x transfer rate supported */ #define PCI_AGP_STATUS_RATE2 0x0002 /* 2x transfer rate supported */ #define PCI_AGP_STATUS_RATE1 0x0001 /* 1x transfer rate supported */ #define PCI_AGP_COMMAND 8 /* Control register */ #define PCI_AGP_COMMAND_RQ_MASK 0xff000000 /* Master: Maximum number of requests */ #define PCI_AGP_COMMAND_SBA 0x0200 /* Sideband addressing enabled */ #define PCI_AGP_COMMAND_AGP 0x0100 /* Allow processing of AGP transactions */ #define PCI_AGP_COMMAND_64BIT 0x0020 /* Allow processing of 64-bit addresses */ #define PCI_AGP_COMMAND_FW 0x0010 /* Force FW transfers */ #define PCI_AGP_COMMAND_RATE4 0x0004 /* Use 4x rate */ #define PCI_AGP_COMMAND_RATE2 0x0002 /* Use 2x rate */ #define PCI_AGP_COMMAND_RATE1 0x0001 /* Use 1x rate */ #define PCI_AGP_SIZEOF 12 #define PCI_IO_RANGE_MASK (~0x0fUL) #define PCI_SEC_STATUS 0x1e /* Secondary status register, only bit 14 used */ #define PCI_MEMORY_BASE 0x20 /* Memory range behind */ #define PCI_MEMORY_LIMIT 0x22 #define PCI_MEMORY_RANGE_TYPE_MASK 0x0fUL #define PCI_MEMORY_RANGE_MASK (~0x0fUL) #define PCI_PREF_MEMORY_BASE 0x24 /* Prefetchable memory range behind */ #define PCI_PREF_MEMORY_LIMIT 0x26 #define PCI_PREF_RANGE_TYPE_MASK 0x0fUL #define PCI_PREF_RANGE_TYPE_32 0x00 #define PCI_PREF_RANGE_TYPE_64 0x01 #define PCI_PREF_RANGE_MASK (~0x0fUL) #define PCI_PREF_BASE_UPPER32 0x28 /* Upper half of prefetchable memory range */ #define PCI_PREF_LIMIT_UPPER32 0x2c #define PCI_IO_BASE_UPPER16 0x30 /* Upper half of I/O addresses */ #define PCI_IO_LIMIT_UPPER16 0x32 /* 0x34 same as for htype 0 */ /* 0x35-0x3b is reserved */ #define PCI_ROM_ADDRESS1 0x38 /* Same as PCI_ROM_ADDRESS, but for htype 1 */ /* 0x3c-0x3d are same as for htype 0 */ #define PCI_BRIDGE_CONTROL 0x3e #define PCI_BRIDGE_CTL_PARITY 0x01 /* Enable parity detection on secondary interface */ #define PCI_BRIDGE_CTL_SERR 0x02 /* The same for SERR forwarding */ #define PCI_BRIDGE_CTL_ISA 0x04 /* Enable ISA mode */ |
