ArmVirtPkg/Library/ArmVirtPL031FdtClientLib/ArmVirtPL031FdtClientLib.c

   1 /** @file
   2   FDT client library for ARM's PL031 RTC driver
   3
   4   Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8 **/
   9
  10 #include <Uefi.h>
  11
  12 #include <Library/BaseLib.h>
  13 #include <Library/DebugLib.h>
  14 #include <Library/PcdLib.h>
  15 #include <Library/UefiBootServicesTableLib.h>
  16
  17 #include <Protocol/FdtClient.h>
  18
  19 RETURN_STATUS
  20 EFIAPI
  21 ArmVirtPL031FdtClientLibConstructor (
  22   VOID
  23   )
  24 {
  25   EFI_STATUS                    Status;
  26   FDT_CLIENT_PROTOCOL           *FdtClient;
  27   INT32                         Node;
  28   CONST UINT64                  *Reg;
  29   UINT32                        RegSize;
  30   UINT64                        RegBase;
  31   RETURN_STATUS                 PcdStatus;
  32
  33   Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
  34                   (VOID **)&FdtClient);
  35   ASSERT_EFI_ERROR (Status);
  36
  37   Status = FdtClient->FindCompatibleNode (FdtClient, "arm,pl031", &Node);
  38   if (EFI_ERROR (Status)) {
  39     DEBUG ((EFI_D_WARN, "%a: No 'arm,pl031' compatible DT node found\n",
  40       __FUNCTION__));
  41     return EFI_SUCCESS;
  42   }
  43
  44   Status = FdtClient->GetNodeProperty (FdtClient, Node, "reg",
  45                         (CONST VOID **)&Reg, &RegSize);
  46   if (EFI_ERROR (Status)) {
  47     DEBUG ((EFI_D_WARN,
  48       "%a: No 'reg' property found in 'arm,pl031' compatible DT node\n",
  49       __FUNCTION__));
  50     return EFI_SUCCESS;
  51   }
  52
  53   ASSERT (RegSize == 16);
  54
  55   RegBase = SwapBytes64 (Reg[0]);
  56   ASSERT (RegBase < MAX_UINT32);
  57
  58   PcdStatus = PcdSet32S (PcdPL031RtcBase, (UINT32)RegBase);
  59   ASSERT_RETURN_ERROR (PcdStatus);
  60
  61   DEBUG ((EFI_D_INFO, "Found PL031 RTC @ 0x%Lx\n", RegBase));
  62
  63   //
  64   // UEFI takes ownership of the RTC hardware, and exposes its functionality
  65   // through the UEFI Runtime Services GetTime, SetTime, etc. This means we
  66   // need to disable it in the device tree to prevent the OS from attaching
  67   // its device driver as well.
  68   //
  69   Status = FdtClient->SetNodeProperty (FdtClient, Node, "status",
  70                         "disabled", sizeof ("disabled"));
  71   if (EFI_ERROR (Status)) {
  72       DEBUG ((EFI_D_WARN, "Failed to set PL031 status to 'disabled'\n"));
  73   }
  74
  75   return EFI_SUCCESS;
  76 }