Windows pci register access

windowsのpci register access

Pci reg access example.

#define LSZ sizeof(ULONG)
#define HEADERSIZE (FIELD_OFFSET (PCI_COMMON_CONFIG, DeviceSpecific)) / LSZ

 // The PCI_COMMON_CONFIG structure includes 
// device specific data. The following
// structure is used to retrieve the
// 64 bytes of data that precedes the
// device-specific data.

typedef struct {
    ULONG  Reserved[HEADERSIZE];
} PCI_COMMON_HEADER, *PPCI_COMMON_HEADER;

PCI_COMMON_HEADER Header;
PCI_COMMON_CONFIG *pPciConfig = (PCI_COMMON_CONFIG *)&Header;
// declare power management capabilities header
 PCI_PM_CAPABILITY  PowerMgmtCapability;
PCI_PM_CAPABILITY  *pPowerMgmtCapability = &Capability; 
UCHAR CapabilityOffset;

// Read the first part of the header
// to get the status register and
// the capabilities pointer.
// The "capabilities pointer" is
// actually an offset from the
// beginning of the header to a
// linked list of capabilities.
BusInterface.GetBusData(Context,
    PCI_WHICHSPACE_CONFIG,
    pPciConfig, // output buffer
    0, // offset of the capability to read
 sizeof(PCI_COMMON_HEADER)); // just 64 bytes

// Check the Status register to see if 
// this device supports capability lists.
 
if ((pPciConfig->Status &
   PCI_STATUS_CAPABILITIES_LIST) == 0) {
   // does not support capabilities list
   return(STATUS_NOT_IMPLEMENTED);
}

// The device supports capability lists.
// Find the capabilities.

// The position of the capabilities pointer
// in the header depends on whether this is 
// a bridge type device. Check the type.

if ((pPciConfig->HeaderType & 
   (~PCI_MULTIFUNCTION)) == PCI_BRIDGE_TYPE) {
   CapabilityOffset = 
       pPciConfig->u.type1.CapabilitiesPtr;
} else if ((pPciConfig->HeaderType & 
   (~PCI_MULTIFUNCTION)) == PCI_CARDBUS_TYPE) {
   CapabilityOffset = 
       pPciConfig->u.type2.CapabilitiesPtr;
} else {
   CapabilityOffset = 
       pPciConfig->u.type0.CapabilitiesPtr;
}

// Loop through the capabilities in search
// of the power management capability. The
// list is NULL-terminated, so the last 
// offset will always be zero.

while (CapabilityOffset != 0) {

    // Read the header of the capability at 
    // this offset.

    // If the retrieved capability is not
    // the power management capability that
    // we are looking for, follow the
    // link to the next capability and
    // continue looping.

    BusInterface.GetBusData(Context,
        PCI_WHICHSPACE_CONFIG,
        pPowerMgmtCapability,
        CapabilityOffset,
        sizeof(PCI_CAPABILITIES_HEADER));

    if (Capability->Header.CapabilityID ==
 PCI_CAPABILITY_ID_POWER_MANAGEMENT) {
        // Found the power management capability
        break;
    } else {
        // This is some other capability.
        // Keep looking for the power 
        // management capability.
        CapabilityOffset = Capability->Header.Next;
    }
}

if (CapabilityOffset == 0) {
    // We didn't find a power management
    // capability. Return an error.
    return(STATUS_NOT_IMPLEMENTED);
}

// Skip past the capabilities header and read
// the rest of the power management capability

BusInterface.GetBusData(Context,
   PCI_WHICHSPACE_CONFIG,
   // write to location immediately following header
   & (pPowerMgmtCapability->Header) + 1, 
   CapabilityOffset + 
       sizeof(PCI_CAPABILITIES_HEADER),
   sizeof(PCI_PM_CAPABILITY) - 
       sizeof(PCI_CAPABILITIES_HEADER)
);

ref

https://docs.microsoft.com/en-gb/windows-hardware/drivers/pci/accessing-pci-device-configuration-space