c46cc6f149
Haswell ULT devices have a 24MHz package-level counter. Use this counter to provide a timer_monotonic_get() implementation. Change-Id: Ic79843fcbfbbb6462ee5ebd12b39502307750dbb Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: http://review.coreboot.org/3153 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2013 Google, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdint.h>
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#include <cpu/x86/msr.h>
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#include <timer.h>
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#define MSR_COUNTER_24_MHz 0x637
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static struct monotonic_counter {
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int initialized;
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struct mono_time time;
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uint32_t last_value;
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} mono_counter;
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static inline uint32_t read_counter_msr(void)
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{
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/* Even though the MSR is 64-bit it is assumed that the hardware
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* is polled frequently enough to only use the lower 32-bits. */
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msr_t counter_msr;
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counter_msr = rdmsr(MSR_COUNTER_24_MHz);
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return counter_msr.lo;
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}
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void timer_monotonic_get(struct mono_time *mt)
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{
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uint32_t current_tick;
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uint32_t usecs_elapsed;
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if (!mono_counter.initialized) {
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mono_counter.last_value = read_counter_msr();
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mono_counter.initialized = 1;
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}
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current_tick = read_counter_msr();
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usecs_elapsed = (current_tick - mono_counter.last_value) / 24;
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/* Update current time and tick values only if a full tick occurred. */
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if (usecs_elapsed) {
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mono_time_add_usecs(&mono_counter.time, usecs_elapsed);
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mono_counter.last_value = current_tick;
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}
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/* Save result. */
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*mt = mono_counter.time;
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}
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