On January 25, 2018 4:53:06 PM GMT-02:00, Rafael Machado
<[email protected]> wrote:
>Hi everyone.
>
>I'm currently work on a task, and I need to write some data at a DMA
>buffer.
>At the UEFI Driver Writer's guide, at page 359 there is a sample code
>of
>how to do that.
>
>Considering that code and adapting to my scenario I got the following
>function (some debug prints are present for clarification):
>
>EFI_STATUS
>EFIAPI
>DoBusMasterWrite (
> IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *PciIo,
> IN UINT8 *HostAddress,
> IN UINTN *Length,
> IN UINT32 Value
>)
>{
> EFI_STATUS Status;
> UINTN NumberOfBytes;
> EFI_PHYSICAL_ADDRESS DeviceAddress;
> VOID *Mapping;
> UINT64 ReadValue;
>
> //
> // Call Map() to retrieve the DeviceAddress to use for the bus
> // master write operation. The Map() function may not support
> // performing a DMA operation for the entire length, so it may
> // be broken up into smaller DMA operations.
> //
> NumberOfBytes = *Length;
> Status = PciIo->Map (PciIo, // This
>
> EfiPciIoOperationBusMasterCommonBuffer, // Operation
> (VOID *)HostAddress, // HostAddress
> &NumberOfBytes, // NumberOfBytes
> &DeviceAddress, //DeviceAddress
> &Mapping //Mapping);
>
> if (EFI_ERROR (Status)) {
> return Status;
> }
>
> //
> // Write the data to the desired address
> // This write operation also starts the DMA transaction
> //
> Status = PciIo->Mem.Write (PciIo, // This
> EfiPciIoWidthUint32, // Width
> *HostAddress,
> 1, // Count
> &Value // Buffer
> );
I'm not sure, but I think you're passing the wrong value to the 3rd parameter
(Address). Shouldn't that be "(UINT64)(UINTN)HostAddress"?
Paulo
>
> Print(L"NumberOfBytes: %d\r\n", NumberOfBytes);
> Print(L"address: 0x%x\r\n", HostAddress);
> Print(L"Value: 0x%x\r\n", Value);
> Print(L"Status: %r\r\n", Status);
>
> if (EFI_ERROR (Status)) {
>return Status;
> }
>
> //
> // The operations performed by PollMem() also flush all posted
> // writes from the PCI bus master and through PCI-to-PCI bridges.
> //
> Status = PciIo->PollMem (PciIo, // This
> EfiPciIoWidthUint32, // Width
> *HostAddress, // Offset
> 0xFFFFFFFF,// Mask
> Value,// Value
> EFI_TIMER_PERIOD_SECONDS
>(1), // Timeout
> &ReadValue // Result
> );
> Print(L"Status2: %r\r\n", Status);
>
> if (EFI_ERROR (Status)) {
>return Status;
> }
>
> //
> // Call Flush() to flush all write transactions to system memory
> //
> Status = PciIo->Flush (PciIo);
> Print(L"Status3: %r\r\n", Status);
>
> if (EFI_ERROR (Status)) {
>return Status;
> }
>
> //
> // Call Unmap() to complete the bus master write operation
> //
> Status = PciIo->Unmap (PciIo, Mapping);
> Print(L"Status4: %r\r\n", Status);
>
> if (EFI_ERROR (Status)) {
>return Status;
> }
> return Status;
>}
>
>The output of this function is this:
> NumberOfBytes: 4
> address: 0xCCCAC000
> Value: 0xAAAAA
> Status: Success
> Status2: Success
> Status3: Success
> Status4: Success
>
>The problem is that when I try to read this memory content using the
>dmem
>command at the efiShell the value 0xAAAAA cannot be found. Seems
>something
>is locking the DMA trasaction.
>Can someone give me some light?
>
>Thanks and Regard
>Rafael R. Machado
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>[email protected]
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--
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