PcAtChipsetPkg AcpiTimerLib: Clear bits [31:24] after reading by IoRead32()

Clear bits [31:24] after reading ACPI timer count by IoRead32(), and also add
comments "Note: The implementation uses the lower 24-bits of the ACPI timer
and is compatible with both 24-bit and 32-bit ACPI timers." in INF.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Star Zeng 2016-09-28 18:17:55 +08:00
parent 3643e8e70d
commit b3b58d4da7
3 changed files with 15 additions and 9 deletions

View File

@ -162,14 +162,14 @@ InternalAcpiDelay (
// //
// The target timer count is calculated here // The target timer count is calculated here
// //
Ticks = IoRead32 (Port) + Delay; Ticks = IoBitFieldRead32 (Port, 0, 23) + Delay;
Delay = BIT22; Delay = BIT22;
// //
// Wait until time out // Wait until time out
// Delay >= 2^23 could not be handled by this function // Delay >= 2^23 could not be handled by this function
// Timer wrap-arounds are handled correctly by this function // Timer wrap-arounds are handled correctly by this function
// //
while (((Ticks - IoRead32 (Port)) & BIT23) == 0) { while (((Ticks - IoBitFieldRead32 (Port, 0, 23)) & BIT23) == 0) {
CpuPause (); CpuPause ();
} }
} while (Times-- > 0); } while (Times-- > 0);
@ -371,7 +371,7 @@ InternalCalculateTscFrequency (
// Use 363 * 9861 = 3579543 Hz which is within 2 Hz of ACPI_TIMER_FREQUENCY. // Use 363 * 9861 = 3579543 Hz which is within 2 Hz of ACPI_TIMER_FREQUENCY.
// 363 counts is a calibration time of 101.4 uS. // 363 counts is a calibration time of 101.4 uS.
// //
Ticks = IoRead32 (TimerAddr) + 363; Ticks = IoBitFieldRead32 (TimerAddr, 0, 23) + 363;
StartTSC = AsmReadTsc (); // Get base value for the TSC StartTSC = AsmReadTsc (); // Get base value for the TSC
// //
@ -380,7 +380,7 @@ InternalCalculateTscFrequency (
// When the current ACPI timer value is greater than 'Ticks', // When the current ACPI timer value is greater than 'Ticks',
// the while loop will exit. // the while loop will exit.
// //
while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) { while (((Ticks - IoBitFieldRead32 (TimerAddr, 0, 23)) & BIT23) == 0) {
CpuPause(); CpuPause();
} }
EndTSC = AsmReadTsc (); // TSC value 101.4 us later EndTSC = AsmReadTsc (); // TSC value 101.4 us later

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@ -4,7 +4,10 @@
# Provides basic timer support using the ACPI timer hardware. The performance # Provides basic timer support using the ACPI timer hardware. The performance
# counter features are provided by the processors time stamp counter. # counter features are provided by the processors time stamp counter.
# #
# Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.<BR> # Note: The implementation uses the lower 24-bits of the ACPI timer and
# is compatible with both 24-bit and 32-bit ACPI timers.
#
# Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.<BR>
# This program and the accompanying materials # This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD License # are licensed and made available under the terms and conditions of the BSD License
# which accompanies this distribution. The full text of the license may be found at # which accompanies this distribution. The full text of the license may be found at

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@ -4,7 +4,10 @@
# Provides basic timer support using the ACPI timer hardware. The performance # Provides basic timer support using the ACPI timer hardware. The performance
# counter features are provided by the processors time stamp counter. # counter features are provided by the processors time stamp counter.
# #
# Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.<BR> # Note: The implementation uses the lower 24-bits of the ACPI timer and
# is compatible with both 24-bit and 32-bit ACPI timers.
#
# Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.<BR>
# This program and the accompanying materials # This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD License # are licensed and made available under the terms and conditions of the BSD License
# which accompanies this distribution. The full text of the license may be found at # which accompanies this distribution. The full text of the license may be found at