From c46cc6f149c42653344d6e9f3656a4212fc46cef Mon Sep 17 00:00:00 2001 From: Aaron Durbin Date: Mon, 29 Apr 2013 16:57:10 -0500 Subject: haswell: 24MHz monotonic time implementation 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 Reviewed-on: http://review.coreboot.org/3153 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich --- src/cpu/intel/haswell/monotonic_timer.c | 62 +++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 src/cpu/intel/haswell/monotonic_timer.c (limited to 'src/cpu/intel/haswell/monotonic_timer.c') diff --git a/src/cpu/intel/haswell/monotonic_timer.c b/src/cpu/intel/haswell/monotonic_timer.c new file mode 100644 index 0000000000..c51bcbd0c9 --- /dev/null +++ b/src/cpu/intel/haswell/monotonic_timer.c @@ -0,0 +1,62 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2013 Google, Inc. + * + * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include +#include +#include + +#define MSR_COUNTER_24_MHz 0x637 +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; +} -- cgit v1.2.3