On 5/14/20 10:40 AM, Sami Mujawar wrote:
Some virtual machine managers like kvmtool emulate the MC146818
RTC controller in the MMIO space so that architectures that do
not support I/O Mapped I/O can use the RTC. This patch adds MMIO
support to the RTC controller driver.

The PCD PcdRtcUseMmio has been added to select I/O or MMIO support.
   If PcdRtcUseMmio is:
     TRUE  - Indicates the RTC port registers are in MMIO space.
     FALSE - Indicates the RTC port registers are in I/O space.
             Default is I/O space.

When MMIO support is selected (PcdRtcUseMmio == TRUE) the driver
maps the MMIO region used by the RTC as runtime memory so that the
RTC registers are accessible post ExitBootServices.

Signed-off-by: Sami Mujawar <sami.muja...@arm.com>

Acked-by: Ard Biesheuvel <ard.biesheu...@arm.com>

---

Notes:
     v2:
       - Code review comments incorporated.                              [Sami]
v1:
       - Add support to read/write from RTC registers using MMIO access  [Sami]
       - Use wrapper functions for RtcRead/Write accessors               [Leif]
         Ref: https://edk2.groups.io/g/devel/topic/30915281#30695

  PcAtChipsetPkg/PcAtChipsetPkg.dec                                          |  
 8 ++
  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c                         | 
117 ++++++++++++++++--
  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h                         |  
31 +++++
  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c                    | 
130 +++++++++++++++++++-
  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf |  
 8 ++
  5 files changed, 280 insertions(+), 14 deletions(-)

diff --git a/PcAtChipsetPkg/PcAtChipsetPkg.dec 
b/PcAtChipsetPkg/PcAtChipsetPkg.dec
index 
88de5cceea593176c3a2425a5963b66b789f2b9e..76d0c7eda69bb505914ba904e09c89de170f69ae
 100644
--- a/PcAtChipsetPkg/PcAtChipsetPkg.dec
+++ b/PcAtChipsetPkg/PcAtChipsetPkg.dec
@@ -6,6 +6,7 @@
  #
  # Copyright (c) 2009 - 2019, Intel Corporation. All rights reserved.<BR>
  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
  #
  # SPDX-License-Identifier: BSD-2-Clause-Patent
  #
@@ -142,5 +143,12 @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
    # @Prompt RTC Update Timeout Value.
    
gPcAtChipsetPkgTokenSpaceGuid.PcdRealTimeClockUpdateTimeout|100000|UINT32|0x00000020
+ ## Indicates the RTC port registers are in MMIO space, or in I/O space.
+  #  Default is I/O space.<BR><BR>
+  #   TRUE  - RTC port registers are in MMIO space.<BR>
+  #   FALSE - RTC port registers are in I/O space.<BR>
+  # @Prompt RTC port registers use MMIO.
+  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio|FALSE|BOOLEAN|0x00000021
+
  [UserExtensions.TianoCore."ExtraFiles"]
    PcAtChipsetPkgExtra.uni
diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c 
b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
index 
52af17941786ef81c3911512ee64551724e67209..df8dea83ab27bbba12351096d1bfd9ea31accb60
 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
@@ -3,6 +3,7 @@
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent @@ -10,6 +11,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent #include "PcRtc.h" +extern EFI_PHYSICAL_ADDRESS mRtcRegisterBase;
+
  //
  // Days of month.
  //
@@ -21,6 +24,28 @@ UINTN mDayOfMonth[] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 
31, 30, 31 };
  CHAR16 mTimeZoneVariableName[] = L"RTC";
/**
+  A function pointer that evaluates to a function that reads the RTC content
+  through its registers either using IO or MMIO access.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+
+  @return The data of UINT8 type read from RTC.
+**/
+RTC_READ  RtcRead;
+
+/**
+  A function pointer that evaluates to a function that reads the RTC content
+  through its registers either using IO or MMIO access.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+
+  @return The data of UINT8 type read from RTC.
+**/
+RTC_WRITE RtcWrite;
+
+/**
    Compare the Hour, Minute and Second of the From time and the To time.
Only compare H/M/S in EFI_TIME and ignore other fields here.
@@ -54,41 +79,99 @@ IsWithinOneDay (
    );
/**
-  Read RTC content through its registers.
+  Read RTC content through its registers using IO access.
- @param Address Address offset of RTC. It is recommended to use macros such as
-                   RTC_ADDRESS_SECONDS.
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
@return The data of UINT8 type read from RTC.
  **/
+STATIC
  UINT8
-RtcRead (
+IoRtcRead (
    IN  UINT8 Address
    )
  {
-  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8) (IoRead8 
(PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
+  IoWrite8 (
+    PcdGet8 (PcdRtcIndexRegister),
+    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))
+    );
    return IoRead8 (PcdGet8 (PcdRtcTargetRegister));
  }
/**
-  Write RTC through its registers.
+  Write RTC through its registers  using IO access.
- @param Address Address offset of RTC. It is recommended to use macros such as
-                   RTC_ADDRESS_SECONDS.
-  @param  Data     The content you want to write into RTC.
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+  @param  Data      The content you want to write into RTC.
**/
+STATIC
  VOID
-RtcWrite (
+IoRtcWrite (
    IN  UINT8   Address,
    IN  UINT8   Data
    )
  {
-  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8) (IoRead8 
(PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
+  IoWrite8 (
+    PcdGet8 (PcdRtcIndexRegister),
+    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))
+    );
    IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);
  }
/**
+  Read RTC content through its registers using MMIO access.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+
+  @return The data of UINT8 type read from RTC.
+**/
+STATIC
+UINT8
+MmioRtcRead (
+  IN  UINT8 Address
+  )
+{
+  MmioWrite8 (
+    mRtcRegisterBase,
+    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
+    );
+  return MmioRead8 (
+           mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
+             PcdGet8 (PcdRtcIndexRegister))
+           );
+}
+
+/**
+  Write RTC through its registers using MMIO access.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+  @param  Data      The content you want to write into RTC.
+
+**/
+STATIC
+VOID
+MmioRtcWrite (
+  IN  UINT8   Address,
+  IN  UINT8   Data
+  )
+{
+  MmioWrite8 (
+    mRtcRegisterBase,
+    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
+    );
+  MmioWrite8 (
+    mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
+      PcdGet8 (PcdRtcIndexRegister)),
+    Data
+    );
+}
+
+/**
    Initialize RTC.
@param Global For global use inside this module.
@@ -113,6 +196,18 @@ PcRtcInit (
    BOOLEAN         Pending;
//
+  // Initialize the RtcRead and RtcWrite functions
+  // based on the chosen IO/MMIO access.
+  //
+  if (FixedPcdGetBool (PcdRtcUseMmio)) {
+    RtcRead = MmioRtcRead;
+    RtcWrite = MmioRtcWrite;
+  } else {
+    RtcRead = IoRtcRead;
+    RtcWrite = IoRtcWrite;
+  }
+
+  //
    // Acquire RTC Lock to make access to RTC atomic
    //
    if (!EfiAtRuntime ()) {
diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h 
b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
index 
47293ce44c5a1f4792892892f7da40d7f0a5a001..e64dbbea48f7f0d2f317c65c2e4b93e7b1888efc
 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
@@ -3,6 +3,7 @@
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+Copyright (c) 2019 - 2020, ARM Limited. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent @@ -371,4 +372,34 @@ PcRtcAcpiTableChangeCallback (
    IN EFI_EVENT        Event,
    IN VOID             *Context
    );
+
+/**
+  Function pointer to Read RTC content through its registers.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+
+  @return The data of UINT8 type read from RTC.
+**/
+typedef
+UINT8
+(EFIAPI *RTC_READ) (
+  IN  UINT8 Address
+  );
+
+/**
+  Function pointer to Write RTC through its registers.
+
+  @param  Address   Address offset of RTC. It is recommended to use
+                    macros such as RTC_ADDRESS_SECONDS.
+  @param  Data      The content you want to write into RTC.
+
+**/
+typedef
+VOID
+(EFIAPI *RTC_WRITE) (
+  IN  UINT8   Address,
+  IN  UINT8   Data
+  );
+
  #endif
diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c 
b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
index 
ccda6331373bfe4069b0a59495b5e5cc731c8fc8..5d5dbeaf970ca8eb291c1e094fd764d201f9071e
 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
@@ -2,16 +2,32 @@
    Provides Set/Get time operations.
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-2-Clause-Patent
**/ +#include <Library/DxeServicesTableLib.h>
  #include "PcRtc.h"
PC_RTC_MODULE_GLOBALS mModuleGlobal; EFI_HANDLE mHandle = NULL; +STATIC EFI_EVENT mVirtualAddrChangeEvent;
+
+EFI_PHYSICAL_ADDRESS   mRtcRegisterBase;
+
+//
+// Function pointer for the Rtc Read interface function
+//
+extern RTC_READ   RtcRead;
+
+//
+// Function pointer for the Rtc Write interface function
+//
+extern RTC_WRITE  RtcWrite;
+
  /**
    Returns the current time and date information, and the time-keeping 
capabilities
    of the hardware platform.
@@ -106,6 +122,33 @@ PcRtcEfiSetWakeupTime (
  }
/**
+  Fixup internal data so that EFI can be called in virtual mode.
+  Call the passed in Child Notify event and convert any pointers in
+  lib to virtual mode.
+
+  @param[in]    Event   The Event that is being processed
+  @param[in]    Context Event Context
+**/
+VOID
+EFIAPI
+LibRtcVirtualNotifyEvent (
+  IN EFI_EVENT        Event,
+  IN VOID             *Context
+  )
+{
+  // Only needed if you are going to support the OS calling RTC functions in
+  // virtual mode. You will need to call EfiConvertPointer (). To convert any
+  // stored physical addresses to virtual address. After the OS transitions to
+  // calling in virtual mode, all future runtime calls will be made in virtual
+  // mode.
+  EfiConvertPointer (0x0, (VOID**)&mRtcRegisterBase);
+
+  // Convert the RtcRead and RtcWrite pointers for runtime use.
+  EfiConvertPointer (0x0, (VOID**)&RtcRead);
+  EfiConvertPointer (0x0, (VOID**)&RtcWrite);
+}
+
+/**
    The user Entry Point for PcRTC module.
This is the entry point for PcRTC module. It installs the UEFI runtime service
@@ -125,12 +168,77 @@ InitializePcRtc (
    IN EFI_SYSTEM_TABLE                      *SystemTable
    )
  {
-  EFI_STATUS  Status;
-  EFI_EVENT   Event;
+  EFI_STATUS             Status;
+  EFI_EVENT              Event;
+  EFI_PHYSICAL_ADDRESS   RtcPageBase;
EfiInitializeLock (&mModuleGlobal.RtcLock, TPL_CALLBACK);
    mModuleGlobal.CenturyRtcAddress = GetCenturyRtcAddress ();
+ if (FixedPcdGetBool (PcdRtcUseMmio)) {
+    mRtcRegisterBase = PcdGet8 (PcdRtcIndexRegister);
+    RtcPageBase = mRtcRegisterBase & ~(EFI_PAGE_SIZE - 1);
+
+    // Declare the controller as EFI_MEMORY_RUNTIME
+    Status = gDS->AddMemorySpace (
+                    EfiGcdMemoryTypeMemoryMappedIo,
+                    RtcPageBase,
+                    EFI_PAGE_SIZE,
+                    EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
+                    );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR, "Failed to add memory space. Status = %r\n",
+        Status
+        ));
+      return Status;
+    }
+
+    Status = gDS->AllocateMemorySpace (
+                    EfiGcdAllocateAddress,
+                    EfiGcdMemoryTypeMemoryMappedIo,
+                    0,
+                    EFI_PAGE_SIZE,
+                    &RtcPageBase,
+                    ImageHandle,
+                    NULL
+                    );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "Failed to allocate memory space. Status = %r\n",
+        Status
+        ));
+      gDS->RemoveMemorySpace (
+             RtcPageBase,
+             EFI_PAGE_SIZE
+             );
+      return Status;
+    }
+
+    Status = gDS->SetMemorySpaceAttributes (
+                    RtcPageBase,
+                    EFI_PAGE_SIZE,
+                    EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
+                    );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "Failed to set memory attributes. Status = %r\n",
+        Status
+        ));
+      gDS->FreeMemorySpace (
+               RtcPageBase,
+               EFI_PAGE_SIZE
+               );
+      gDS->RemoveMemorySpace (
+             RtcPageBase,
+             EFI_PAGE_SIZE
+             );
+      return Status;
+    }
+  }
+
    Status = PcRtcInit (&mModuleGlobal);
    ASSERT_EFI_ERROR (Status);
@@ -165,7 +273,23 @@ InitializePcRtc (
                    NULL,
                    NULL
                    );
-  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    ASSERT_EFI_ERROR (Status);
+    return Status;
+  }
+
+  if (FixedPcdGetBool (PcdRtcUseMmio)) {
+    // Register for the virtual address change event
+    Status = gBS->CreateEventEx (
+                    EVT_NOTIFY_SIGNAL,
+                    TPL_NOTIFY,
+                    LibRtcVirtualNotifyEvent,
+                    NULL,
+                    &gEfiEventVirtualAddressChangeGuid,
+                    &mVirtualAddrChangeEvent
+                    );
+    ASSERT_EFI_ERROR (Status);
+  }
return Status;
  }
diff --git 
a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf 
b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
index 
c73ee98105e510f9e4e23c1a6c1e5c505325d2c9..3a373d11f8bfc7df0e4d00be8b43e90bfa06b192
 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
@@ -6,6 +6,7 @@
  #
  # Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
  #
  # SPDX-License-Identifier: BSD-2-Clause-Patent
  #
@@ -48,6 +49,7 @@ [LibraryClasses]
    BaseLib
    PcdLib
    ReportStatusCodeLib
+  DxeServicesTableLib
[Protocols]
    gEfiRealTimeClockArchProtocolGuid             ## PRODUCES
@@ -61,10 +63,13 @@ [Guids]
    ## SOMETIMES_CONSUMES ## SystemTable
    gEfiAcpiTableGuid
+ gEfiEventVirtualAddressChangeGuid
+
  [FixedPcd]
    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterA     ## CONSUMES
    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterB     ## CONSUMES
    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterD     ## CONSUMES
+  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio                   ## CONSUMES
[Pcd]
    gPcAtChipsetPkgTokenSpaceGuid.PcdRealTimeClockUpdateTimeout   ## CONSUMES
@@ -76,5 +81,8 @@ [Pcd]
  [Depex]
    gEfiVariableArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
+[Depex.common.DXE_RUNTIME_DRIVER]
+  gEfiCpuArchProtocolGuid
+
  [UserExtensions.TianoCore."ExtraFiles"]
    PcRtcExtra.uni



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