ArmVirtPkg/Library/ArmVirtPL031FdtClientLib/ArmVirtPL031FdtClientLib.c

/** @file
  FDT client library for ARM's PL031 RTC driver

  Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>

  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Uefi.h>

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/PcdLib.h>
#include <Library/UefiBootServicesTableLib.h>

#include <Protocol/FdtClient.h>

RETURN_STATUS
EFIAPI
ArmVirtPL031FdtClientLibConstructor (
  VOID
  )
{
  EFI_STATUS                    Status;
  FDT_CLIENT_PROTOCOL           *FdtClient;
  INT32                         Node;
  CONST UINT64                  *Reg;
  UINT32                        RegSize;
  UINT64                        RegBase;
  RETURN_STATUS                 PcdStatus;

  Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
                  (VOID **)&FdtClient);
  ASSERT_EFI_ERROR (Status);

  Status = FdtClient->FindCompatibleNode (FdtClient, "arm,pl031", &Node);
  if (EFI_ERROR (Status)) {
    DEBUG ((EFI_D_WARN, "%a: No 'arm,pl031' compatible DT node found\n",
      __FUNCTION__));
    return EFI_SUCCESS;
  }

  Status = FdtClient->GetNodeProperty (FdtClient, Node, "reg",
                        (CONST VOID **)&Reg, &RegSize);
  if (EFI_ERROR (Status)) {
    DEBUG ((EFI_D_WARN,
      "%a: No 'reg' property found in 'arm,pl031' compatible DT node\n",
      __FUNCTION__));
    return EFI_SUCCESS;
  }

  ASSERT (RegSize == 16);

  RegBase = SwapBytes64 (Reg[0]);
  ASSERT (RegBase < MAX_UINT32);

  PcdStatus = PcdSet32S (PcdPL031RtcBase, (UINT32)RegBase);
  ASSERT_RETURN_ERROR (PcdStatus);

  DEBUG ((EFI_D_INFO, "Found PL031 RTC @ 0x%Lx\n", RegBase));

  //
  // UEFI takes ownership of the RTC hardware, and exposes its functionality
  // through the UEFI Runtime Services GetTime, SetTime, etc. This means we
  // need to disable it in the device tree to prevent the OS from attaching
  // its device driver as well.
  //
  Status = FdtClient->SetNodeProperty (FdtClient, Node, "status",
                        "disabled", sizeof ("disabled"));
  if (EFI_ERROR (Status)) {
      DEBUG ((EFI_D_WARN, "Failed to set PL031 status to 'disabled'\n"));
  }

  return EFI_SUCCESS;
}