[PATCH v2 1/3] EmbeddedPkg/RealTimeClockRuntimeDxe: move common functionality into core

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

RealTimeClockRuntimeDxe defers the hardware/platform specific handling
of reading/setting the hardware clock to RealTimeClockLib, but for
unknown reasons, it also defers common functionality such as input
validation and recording the timezone and DST settings (which are
informational only and not managed by hardware)

This has led to a lot of duplication in implementations of RealTimeClockLib
as well as TimeBaseLib, to the point where each library implementation
has its own set of UEFI variables to record the timezone and DST settings.
This makes little sense, and so let's update RealTimeClockRuntimeDxe now
to allow future implementations to rely on the core driver to take care of
these things.

Note that reading the timezone and DST settings occurs before calling into
the library, so we can phase out this behavior gradually from library
implementations in EDK2, edk2-platforms or out of tree.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClock.c             | 171 +++++++++++++++++++-
 EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf |  11 +-
 2 files changed, 171 insertions(+), 11 deletions(-)

diff --git a/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClock.c b/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClock.c
index f1e067c0b59e..6b7cc876fa33 100644
--- a/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClock.c
+++ b/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClock.c
@@ -1,10 +1,8 @@
 /** @file
   Implement EFI RealTimeClock runtime services via RTC Lib.
 
-  Currently this driver does not support runtime virtual calling.
-
-
   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+  Copyright (c) 2017, 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
@@ -17,14 +15,116 @@
 **/
 
 #include <PiDxe.h>
+#include <Library/DebugLib.h>
+#include <Library/RealTimeClockLib.h>
 #include <Library/UefiLib.h>
 #include <Library/UefiBootServicesTableLib.h>
-#include <Library/RealTimeClockLib.h>
+#include <Library/UefiRuntimeLib.h>
 #include <Protocol/RealTimeClock.h>
 
 EFI_HANDLE  mHandle = NULL;
 
+//
+// These values can be set by SetTime () and need to be returned by GetTime ()
+// but cannot usually be kept by the RTC hardware, so we store them in a UEFI
+// variable instead.
+//
+typedef struct {
+  INT16           TimeZone;
+  UINT8           Daylight;
+} NON_VOLATILE_TIME_SETTINGS;
+
+STATIC CONST CHAR16 mTimeSettingsVariableName[] = L"RtcTimeSettings";
+STATIC NON_VOLATILE_TIME_SETTINGS mTimeSettings;
+
+STATIC
+BOOLEAN
+IsValidTimeZone (
+  IN  INT16  TimeZone
+  )
+{
+  return TimeZone == EFI_UNSPECIFIED_TIMEZONE ||
+         (TimeZone >= -1440 && TimeZone <= 1440);
+}
+
+STATIC
+BOOLEAN
+IsValidDaylight (
+  IN  INT8  Daylight
+  )
+{
+  return Daylight == 0 ||
+         Daylight == EFI_TIME_ADJUST_DAYLIGHT ||
+         Daylight == (EFI_TIME_ADJUST_DAYLIGHT | EFI_TIME_IN_DAYLIGHT);
+}
 
+STATIC
+BOOLEAN
+EFIAPI
+IsLeapYear (
+  IN EFI_TIME   *Time
+  )
+{
+  if (Time->Year % 4 == 0) {
+    if (Time->Year % 100 == 0) {
+      if (Time->Year % 400 == 0) {
+        return TRUE;
+      } else {
+        return FALSE;
+      }
+    } else {
+      return TRUE;
+    }
+  } else {
+    return FALSE;
+  }
+}
+
+STATIC CONST INTN mDayOfMonth[12] = {
+  31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+STATIC
+BOOLEAN
+EFIAPI
+IsDayValid (
+  IN  EFI_TIME  *Time
+  )
+{
+  ASSERT (Time->Day >= 1);
+  ASSERT (Time->Day <= mDayOfMonth[Time->Month - 1]);
+  ASSERT (Time->Month != 2 || (IsLeapYear (Time) && Time->Day <= 29));
+
+  if (Time->Day < 1 ||
+      Time->Day > mDayOfMonth[Time->Month - 1] ||
+      (Time->Month == 2 && (!IsLeapYear (Time) && Time->Day > 28))) {
+    return FALSE;
+  }
+  return TRUE;
+}
+
+STATIC
+BOOLEAN
+EFIAPI
+IsTimeValid(
+  IN EFI_TIME *Time
+  )
+{
+  // Check the input parameters are within the range specified by UEFI
+  if (Time->Year   < 1900               ||
+      Time->Year   > 9999               ||
+      Time->Month  < 1                  ||
+      Time->Month  > 12                 ||
+      !IsDayValid (Time)                ||
+      Time->Hour   > 23                 ||
+      Time->Minute > 59                 ||
+      Time->Second > 59                 ||
+      !IsValidTimeZone (Time->TimeZone) ||
+      !IsValidDaylight (Time->Daylight)) {
+    return FALSE;
+  }
+  return TRUE;
+}
 
 /**
   Returns the current time and date information, and the time-keeping capabilities
@@ -43,9 +143,20 @@ EFI_STATUS
 EFIAPI
 GetTime (
   OUT EFI_TIME                *Time,
-  OUT  EFI_TIME_CAPABILITIES  *Capabilities
+  OUT EFI_TIME_CAPABILITIES   *Capabilities
   )
 {
+  if (Time == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // Set these first so the RealTimeClockLib implementation
+  // can override them based on its own settings.
+  //
+  Time->TimeZone = mTimeSettings.TimeZone;
+  Time->Daylight = mTimeSettings.Daylight;
+
   return LibGetTime (Time, Capabilities);
 }
 
@@ -67,7 +178,41 @@ SetTime (
   IN EFI_TIME                *Time
   )
 {
-  return LibSetTime (Time);
+  EFI_STATUS        Status;
+  BOOLEAN           TimeSettingsChanged;
+
+  if (Time == NULL || !IsTimeValid (Time)) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  TimeSettingsChanged = FALSE;
+  if (mTimeSettings.TimeZone != Time->TimeZone ||
+      mTimeSettings.Daylight != Time->Daylight) {
+
+    mTimeSettings.TimeZone = Time->TimeZone;
+    mTimeSettings.Daylight = Time->Daylight;
+    TimeSettingsChanged = TRUE;
+  }
+
+  Status = LibSetTime (Time);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  if (TimeSettingsChanged) {
+    Status = EfiSetVariable (
+               (CHAR16 *)mTimeSettingsVariableName,
+               &gEfiCallerIdGuid,
+               EFI_VARIABLE_NON_VOLATILE |
+               EFI_VARIABLE_BOOTSERVICE_ACCESS |
+               EFI_VARIABLE_RUNTIME_ACCESS,
+               sizeof (mTimeSettings),
+               (VOID *)&mTimeSettings);
+    if (EFI_ERROR (Status)) {
+      return EFI_DEVICE_ERROR;
+    }
+  }
+  return EFI_SUCCESS;
 }
 
 
@@ -138,12 +283,26 @@ InitializeRealTimeClock (
   )
 {
   EFI_STATUS  Status;
+  UINTN       Size;
 
   Status = LibRtcInitialize (ImageHandle, SystemTable);
   if (EFI_ERROR (Status)) {
     return Status;
   }
 
+  Size = sizeof (mTimeSettings);
+  Status = EfiGetVariable ((CHAR16 *)mTimeSettingsVariableName,
+                  &gEfiCallerIdGuid, NULL, &Size, (VOID *)&mTimeSettings);
+  if (EFI_ERROR (Status) ||
+      !IsValidTimeZone (mTimeSettings.TimeZone) ||
+      !IsValidDaylight (mTimeSettings.Daylight)) {
+    DEBUG ((DEBUG_WARN, "%a: using default timezone/daylight settings\n",
+      __FUNCTION__));
+
+    mTimeSettings.TimeZone = EFI_UNSPECIFIED_TIMEZONE;
+    mTimeSettings.Daylight = 0;
+  }
+
   SystemTable->RuntimeServices->GetTime       = GetTime;
   SystemTable->RuntimeServices->SetTime       = SetTime;
   SystemTable->RuntimeServices->GetWakeupTime = GetWakeupTime;
diff --git a/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf b/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
index 186d4610bd42..d0520392f145 100644
--- a/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
+++ b/EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf
@@ -1,8 +1,8 @@
 #/** @file
-# Reset Architectural Protocol Driver as defined in PI
+#  Real Time Clock Architectural Protocol Driver as defined in PI
 #
-# This Reset module simulates system reset by process exit on NT.
-# Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2017, 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
@@ -31,10 +31,11 @@ [Packages]
   EmbeddedPkg/EmbeddedPkg.dec
 
 [LibraryClasses]
-  UefiBootServicesTableLib
-  UefiDriverEntryPoint
   DebugLib
   RealTimeClockLib
+  UefiBootServicesTableLib
+  UefiDriverEntryPoint
+  UefiRuntimeLib
 
 [Protocols]
   gEfiRealTimeClockArchProtocolGuid
-- 
2.11.0