All runtime driver should use functions provided by UefiRuntimeLib library class...

[mirror_edk2.git] / EdkModulePkg / Universal / MonotonicCounter / RuntimeDxe / MonotonicCounter.c

diff --git a/EdkModulePkg/Universal/MonotonicCounter/RuntimeDxe/MonotonicCounter.c b/EdkModulePkg/Universal/MonotonicCounter/RuntimeDxe/MonotonicCounter.c
index 6e4350f0ed1abff7e1f60427b9a8506420ca2bbd..f79038657ae6aed4ae7c13a1d4698e1b009830f2 100644 (file)
--- a/EdkModulePkg/Universal/MonotonicCounter/RuntimeDxe/MonotonicCounter.c
+++ b/EdkModulePkg/Universal/MonotonicCounter/RuntimeDxe/MonotonicCounter.c
@@ -33,7 +33,6 @@ EFI_HANDLE  mMonotonicCounterHandle = NULL;
 //\r
 UINT64      mEfiMtc;\r
 \r
-\r
 //\r
 // Event to use to update the Mtc's high part when wrapping\r
 //\r
@@ -100,6 +99,39 @@ Returns:
   return EFI_SUCCESS;\r
 }\r
 \r
+\r
+/**\r
+  Returns the next high 32 bits of the platform's monotonic counter.\r
+\r
+  The GetNextHighMonotonicCount() function returns the next high 32 bits \r
+  of the platform's monotonic counter. The platform's monotonic counter is \r
+  comprised of two 32 bit quantities:  the high 32 bits and the low 32 bits.  \r
+  During boot service time the low 32 bit value is volatile:  it is reset to \r
+  zero on every system reset and is increased by 1 on every call to GetNextMonotonicCount().\r
+  The high 32 bit value is non-volatile and is increased by 1 whenever the system resets \r
+  or whenever the low 32 bit count [returned by GetNextMonoticCount()] overflows.\r
+  The GetNextMonotonicCount() function is only available at boot services time.  \r
+  If the operating system wishes to extend the platform monotonic counter to runtime, \r
+  it may do so by utilizing GetNextHighMonotonicCount().  To do this, before calling \r
+  ExitBootServices() the operating system would call GetNextMonotonicCount() to obtain \r
+  the current platform monotonic count.  The operating system would then provide an \r
+  interface that returns the next count by:  \r
+    Adding 1 to the last count.\r
+    Before the lower 32 bits of the count overflows, call GetNextHighMonotonicCount().  \r
+    This will increase the high 32 bits of the platform's non-volatile portion of the monotonic \r
+    count by 1.\r
+\r
+  This function may only be called at Runtime.\r
+\r
+  @param[out]   HighCount      Pointer to returned value.\r
+\r
+  @retval EFI_INVALID_PARAMETER If HighCount is NULL.\r
+  @retval EFI_SUCCESS           Operation is successful.\r
+  @retval EFI_OUT_OF_RESOURCES  If variable service reports that not enough storage \r
+                                is available to hold the variable and its data.\r
+  @retval EFI_DEVICE_ERROR      The variable could not be saved due to a hardware failure.\r
+\r
+**/\r
 EFI_STATUS\r
 EFIAPI\r
 MonotonicCounterDriverGetNextHighMonotonicCount (\r
@@ -115,7 +147,6 @@ Returns:
 \r
 --*/\r
 {\r
-  EFI_STATUS  Status;\r
   EFI_TPL     OldTpl;\r
 \r
   //\r
@@ -140,15 +171,14 @@ Returns:
   //\r
   // Update the NvRam store to match the new high part\r
   //\r
-  Status = gRT->SetVariable (\r
-                  mEfiMtcName,\r
-                  &mEfiMtcGuid,\r
-                  EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS,\r
-                  sizeof (UINT32),\r
-                  HighCount\r
-                  );\r
+  return EfiSetVariable (\r
+           mEfiMtcName,\r
+           &mEfiMtcGuid,\r
+           EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS,\r
+           sizeof (UINT32),\r
+           HighCount\r
+           );\r
 \r
-  return Status;\r
 }\r
 \r
 VOID\r