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 (
  34                   &gFdtClientProtocolGuid,
  35                   NULL,
  36                   (VOID **)&FdtClient
  37                   );
  38   ASSERT_EFI_ERROR (Status);
  39
  40   Status = FdtClient->FindCompatibleNode (FdtClient, "arm,pl031", &Node);
  41   if (EFI_ERROR (Status)) {
  42     DEBUG ((
  43       DEBUG_WARN,
  44       "%a: No 'arm,pl031' compatible DT node found\n",
  45       __FUNCTION__
  46       ));
  47     return EFI_SUCCESS;
  48   }
  49
  50   Status = FdtClient->GetNodeProperty (
  51                         FdtClient,
  52                         Node,
  53                         "reg",
  54                         (CONST VOID **)&Reg,
  55                         &RegSize
  56                         );
  57   if (EFI_ERROR (Status)) {
  58     DEBUG ((
  59       DEBUG_WARN,
  60       "%a: No 'reg' property found in 'arm,pl031' compatible DT node\n",
  61       __FUNCTION__
  62       ));
  63     return EFI_SUCCESS;
  64   }
  65
  66   ASSERT (RegSize == 16);
  67
  68   RegBase = SwapBytes64 (Reg[0]);
  69   ASSERT (RegBase < MAX_UINT32);
  70
  71   PcdStatus = PcdSet32S (PcdPL031RtcBase, (UINT32)RegBase);
  72   ASSERT_RETURN_ERROR (PcdStatus);
  73
  74   DEBUG ((DEBUG_INFO, "Found PL031 RTC @ 0x%Lx\n", RegBase));
  75
  76   //
  77   // UEFI takes ownership of the RTC hardware, and exposes its functionality
  78   // through the UEFI Runtime Services GetTime, SetTime, etc. This means we
  79   // need to disable it in the device tree to prevent the OS from attaching
  80   // its device driver as well.
  81   //
  82   Status = FdtClient->SetNodeProperty (
  83                         FdtClient,
  84                         Node,
  85                         "status",
  86                         "disabled",
  87                         sizeof ("disabled")
  88                         );
  89   if (EFI_ERROR (Status)) {
  90     DEBUG ((DEBUG_WARN, "Failed to set PL031 status to 'disabled'\n"));
  91   }
  92
  93   return EFI_SUCCESS;
  94 }