| /* |
| * This file is part of the coreboot project. |
| * |
| * Copyright (C) 2014 Google Inc. |
| * Copyright (C) 2015 Intel Corporation. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; version 2 of the License. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc. |
| */ |
| |
| #include <stdint.h> |
| #include <cpu/x86/msr.h> |
| #include <timer.h> |
| #include <soc/msr.h> |
| |
| static struct monotonic_counter { |
| int initialized; |
| struct mono_time time; |
| uint32_t last_value; |
| } mono_counter; |
| |
| static inline uint32_t read_counter_msr(void) |
| { |
| /* |
| * Even though the MSR is 64-bit it is assumed that the hardware |
| * is polled frequently enough to only use the lower 32-bits. |
| */ |
| msr_t counter_msr; |
| |
| counter_msr = rdmsr(MSR_COUNTER_24_MHZ); |
| |
| return counter_msr.lo; |
| } |
| |
| void timer_monotonic_get(struct mono_time *mt) |
| { |
| uint32_t current_tick; |
| uint32_t usecs_elapsed; |
| |
| if (!mono_counter.initialized) { |
| mono_counter.last_value = read_counter_msr(); |
| mono_counter.initialized = 1; |
| } |
| |
| current_tick = read_counter_msr(); |
| usecs_elapsed = (current_tick - mono_counter.last_value) / 24; |
| |
| /* Update current time and tick values only if a full tick occurred. */ |
| if (usecs_elapsed) { |
| mono_time_add_usecs(&mono_counter.time, usecs_elapsed); |
| mono_counter.last_value = current_tick; |
| } |
| |
| /* Save result. */ |
| *mt = mono_counter.time; |
| } |