/**
Returns a boolean indicating if the firmware configuration interface
is available or not.
This function may change fw_cfg state.
@retval TRUE The interface is available
@retval FALSE The interface is not available
**/
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
VOID
)
{
return InternalQemuFwCfgIsAvailable ();
}
/**
Selects a firmware configuration item for reading.
Following this call, any data read from this item will start from the
beginning of the configuration item's data.
@param[in] QemuFwCfgItem Firmware Configuration item to read
**/
VOID
EFIAPI
QemuFwCfgSelectItem (
IN FIRMWARE_CONFIG_ITEM QemuFwCfgItem
)
{
if (InternalQemuFwCfgIsAvailable ()) {
MmioWrite16 (mFwCfgSelectorAddress, SwapBytes16 ((UINT16)QemuFwCfgItem));
}
}
RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
VOID
)
{
EFI_STATUS Status;
FDT_CLIENT_PROTOCOL *FdtClient;
CONST UINT64 *Reg;
UINT32 RegSize;
UINTN AddressCells, SizeCells;
UINT64 FwCfgSelectorAddress;
UINT64 FwCfgSelectorSize;
UINT64 FwCfgDataAddress;
UINT64 FwCfgDataSize;
UINT64 FwCfgDmaAddress;
UINT64 FwCfgDmaSize;
Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
(VOID **)&FdtClient);
ASSERT_EFI_ERROR (Status);
Status = FdtClient->FindCompatibleNodeReg (FdtClient, "qemu,fw-cfg-mmio",
(CONST VOID **)&Reg, &AddressCells, &SizeCells,
&RegSize);
if (EFI_ERROR (Status)) {
DEBUG ((EFI_D_WARN,
"%a: No 'qemu,fw-cfg-mmio' compatible DT node found (Status == %r)\n",
__FUNCTION__, Status));
return EFI_SUCCESS;
}
ASSERT (AddressCells == 2);
ASSERT (SizeCells == 2);
ASSERT (RegSize == 2 * sizeof (UINT64));
FwCfgDataAddress = SwapBytes64 (Reg[0]);
FwCfgDataSize = 8;
FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
FwCfgSelectorSize = 2;
//
// The following ASSERT()s express
//
// Address + Size - 1 <= MAX_UINTN
//
// for both registers, that is, that the last byte in each MMIO range is
// expressible as a MAX_UINTN. The form below is mathematically
// equivalent, and it also prevents any unsigned overflow before the
// comparison.
//
ASSERT (FwCfgSelectorAddress <= MAX_UINTN - FwCfgSelectorSize + 1);
ASSERT (FwCfgDataAddress <= MAX_UINTN - FwCfgDataSize + 1);
mFwCfgSelectorAddress = FwCfgSelectorAddress;
mFwCfgDataAddress = FwCfgDataAddress;
DEBUG ((EFI_D_INFO, "Found FwCfg @ 0x%Lx/0x%Lx\n", FwCfgSelectorAddress,
FwCfgDataAddress));
if (SwapBytes64 (Reg[1]) >= 0x18) {
FwCfgDmaAddress = FwCfgDataAddress + 0x10;
FwCfgDmaSize = 0x08;
//
// See explanation above.
//
ASSERT (FwCfgDmaAddress <= MAX_UINTN - FwCfgDmaSize + 1);
DEBUG ((EFI_D_INFO, "Found FwCfg DMA @ 0x%Lx\n", FwCfgDmaAddress));
} else {
FwCfgDmaAddress = 0;
}
if (InternalQemuFwCfgIsAvailable ()) {
UINT32 Signature;
QemuFwCfgSelectItem (QemuFwCfgItemSignature);
Signature = QemuFwCfgRead32 ();
if (Signature == SIGNATURE_32 ('Q', 'E', 'M', 'U')) {
//
// For DMA support, we require the DTB to advertise the register, and the
// feature bitmap (which we read without DMA) to confirm the feature.
//
if (FwCfgDmaAddress != 0) {
UINT32 Features;
QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
Features = QemuFwCfgRead32 ();
if ((Features & BIT1) != 0) {
mFwCfgDmaAddress = FwCfgDmaAddress;
InternalQemuFwCfgReadBytes = DmaReadBytes;
}
}
} else {
mFwCfgSelectorAddress = 0;
mFwCfgDataAddress = 0;
}
}
return RETURN_SUCCESS;
}
