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ArmPkg: ArmArchTimerLib: clean up comments 

In the next patch we'll slightly reorganize TimerConstructor(). Let's
improve the comments first.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <Olivier.martin@arm.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16689 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek 2015-02-02 12:01:29 +00:00 committed by lersek
parent 93626a5377
commit 074a67fc80
1 changed files with 21 additions and 10 deletions
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31
ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
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@ -30,32 +30,43 @@ TimerConstructor (
VOID
)
{
// Check if the ARM Generic Timer Extension is implemented
//
// Check if the ARM Generic Timer Extension is implemented.
//
if (ArmIsArchTimerImplemented ()) {
UINTN TimerFreq;
// Check if Architectural Timer frequency is valid number (should not be 0)
//
// Check if Architectural Timer frequency is valid (should not be 0).
//
ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz));
//
// Check if ticks/uS is not 0. The Architectural timer runs at constant
// frequency irrespective of CPU frequency. According to General Timer Ref
// manual lower bound of the frequency is in the range of 1-10MHz
// frequency, irrespective of CPU frequency. According to General Timer
// Ref manual, lower bound of the frequency is in the range of 1-10MHz.
//
ASSERT (TICKS_PER_MICRO_SEC);
#ifdef MDE_CPU_ARM
// Only set the frequency for ARMv7. We expect the secure firmware to have already do it
// If the security extensions are not implemented set Timer Frequency
//
// Only set the frequency for ARMv7. We expect the secure firmware to
// have already done it.
// If the security extension is not implemented, set Timer Frequency
// here.
//
if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
}
#endif
// Architectural Timer Frequency must be set in the Secure privileged(if secure extensions are supported) mode.
// If the reset value (0) is returned just ASSERT.
//
// Architectural Timer Frequency must be set in the Secure privileged
// mode (if secure extension is supported).
// If the reset value (0) is returned, just ASSERT.
//
TimerFreq = ArmGenericTimerGetTimerFreq ();
ASSERT (TimerFreq != 0);
} else {
DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
ASSERT (0);