diff options
Diffstat (limited to 'MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c')
| -rw-r--r-- | MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c | 185 |
1 files changed, 139 insertions, 46 deletions
diff --git a/MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c b/MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c index 9c69cdfb92..e3af546367 100644 --- a/MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c +++ b/MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c @@ -18,25 +18,116 @@ **/
-static
+//
+// The following 2 arrays are used in calculating the frequency of local APIC
+// timer. Refer to IA-32 developers' manual for more details.
+//
+
+GLOBAL_REMOVE_IF_UNREFERENCED
+CONST UINT32 mTimerLibLocalApicFrequencies[] = {
+ 100000000,
+ 133000000,
+ 200000000,
+ 166000000
+};
+
+GLOBAL_REMOVE_IF_UNREFERENCED
+CONST UINT8 mTimerLibLocalApicDivisor[] = {
+ 0x02, 0x04, 0x08, 0x10,
+ 0x02, 0x04, 0x08, 0x10,
+ 0x20, 0x40, 0x80, 0x01,
+ 0x20, 0x40, 0x80, 0x01
+};
+
+/**
+ Internal function to retrieve the base address of local APIC.
+
+ Internal function to retrieve the base address of local APIC.
+
+ @return The base address of local APIC
+
+**/
+STATIC
UINTN
-EFIAPI
-DelayWorker (
- IN UINT64 NDelay
+InternalX86GetApicBase (
+ VOID
+ )
+{
+ return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
+}
+
+/**
+ Internal function to return the frequency of the local APIC timer.
+
+ Internal function to return the frequency of the local APIC timer.
+
+ @param ApicBase The base address of memory mapped registers of local APIC.
+
+ @return The frequency of the timer in Hz.
+
+**/
+STATIC
+UINT32
+InternalX86GetTimerFrequency (
+ IN UINTN ApicBase
+ )
+{
+ return
+ mTimerLibLocalApicFrequencies[AsmMsrBitFieldRead32 (44, 16, 18)] /
+ mTimerLibLocalApicDivisor[MmioBitFieldRead32 (ApicBase + 0x3e0, 0, 3)];
+}
+
+/**
+ Internal function to read the current tick counter of local APIC.
+
+ Internal function to read the current tick counter of local APIC.
+
+ @param ApicBase The base address of memory mapped registers of local APIC.
+
+ @return The tick counter read.
+
+**/
+STATIC
+INT32
+InternalX86GetTimerTick (
+ IN UINTN ApicBase
)
{
- UINT64 Ticks;
-
- Ticks = GetPerformanceCounter ();
- Ticks -= DivU64x32 (
- MultU64x64 (
- GetPerformanceCounterProperties (NULL, NULL),
- NDelay
- ),
- 1000000000u
- );
- while (Ticks <= GetPerformanceCounter ());
- return (UINTN)Ticks;
+ return MmioRead32 (ApicBase + 0x390);
+}
+
+/**
+ Stalls the CPU for at least the given number of ticks.
+
+ Stalls the CPU for at least the given number of ticks. It's invoked by
+ MicroSecondDelay() and NanoSecondDelay().
+
+ @param ApicBase The base address of memory mapped registers of local APIC.
+ @param Delay A period of time to delay in ticks.
+
+**/
+STATIC
+VOID
+InternalX86Delay (
+ IN UINTN ApicBase,
+ IN UINT32 Delay
+ )
+{
+ INT32 Ticks;
+
+ ApicBase = InternalX86GetApicBase ();
+
+ //
+ // The target timer count is calculated here
+ //
+ Ticks = InternalX86GetTimerTick (ApicBase) - Delay;
+
+ //
+ // Wait until time out
+ // Delay > 2^31 could not be handled by this function
+ // Timer wrap-arounds are handled correctly by this function
+ //
+ while (InternalX86GetTimerTick (ApicBase) - Ticks >= 0);
}
/**
@@ -46,7 +137,7 @@ DelayWorker ( @param MicroSeconds The minimum number of microseconds to delay.
- @return Return value depends on implementation.
+ @return MicroSeconds
**/
UINTN
@@ -55,7 +146,20 @@ MicroSecondDelay ( IN UINTN MicroSeconds
)
{
- return DelayWorker (MicroSeconds * 1000ull);
+ UINTN ApicBase;
+
+ ApicBase = InternalX86GetApicBase ();
+ InternalX86Delay (
+ ApicBase,
+ (UINT32)DivU64x32 (
+ MultU64x64 (
+ InternalX86GetTimerFrequency (ApicBase),
+ MicroSeconds
+ ),
+ 1000000u
+ )
+ );
+ return MicroSeconds;
}
/**
@@ -65,7 +169,7 @@ MicroSecondDelay ( @param NanoSeconds The minimum number of nanoseconds to delay.
- @return Return value depends on implementation.
+ @return NanoSeconds
**/
UINTN
@@ -74,17 +178,20 @@ NanoSecondDelay ( IN UINTN NanoSeconds
)
{
- return DelayWorker (NanoSeconds);
-}
+ UINTN ApicBase;
-static
-UINTN
-EFIAPI
-GetApicBase (
- VOID
- )
-{
- return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
+ ApicBase = InternalX86GetApicBase ();
+ InternalX86Delay (
+ ApicBase,
+ (UINT32)DivU64x32 (
+ MultU64x64 (
+ InternalX86GetTimerFrequency (ApicBase),
+ NanoSeconds
+ ),
+ 1000000000u
+ )
+ );
+ return NanoSeconds;
}
/**
@@ -105,7 +212,7 @@ GetPerformanceCounter ( VOID
)
{
- return MmioRead32 (GetApicBase () + 0x390);
+ return InternalX86GetTimerTick (InternalX86GetApicBase ());
}
/**
@@ -138,22 +245,9 @@ GetPerformanceCounterProperties ( IN UINT64 *EndValue
)
{
- static const UINT32 mFrequencies[] = {
- 100000000,
- 133000000,
- 200000000,
- 166000000
- };
- static const UINT8 mDivisor[] = {
- 0x02, 0x04, 0x08, 0x10,
- 0x02, 0x04, 0x08, 0x10,
- 0x20, 0x40, 0x80, 0x01,
- 0x20, 0x40, 0x80, 0x01
- };
-
UINTN ApicBase;
- ApicBase = GetApicBase ();
+ ApicBase = InternalX86GetApicBase ();
if (StartValue != NULL) {
*StartValue = MmioRead32 (ApicBase + 0x380);
@@ -163,6 +257,5 @@ GetPerformanceCounterProperties ( *EndValue = 0;
}
- return mFrequencies[AsmMsrBitFieldRead32 (44, 16, 18)] /
- mDivisor[MmioBitFieldRead32 (ApicBase + 0x3e0, 0, 3)];
+ return InternalX86GetTimerFrequency (ApicBase);
}
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