Aaron Durbin (adurbin@google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/3153
-gerrit
commit d86f98c72eb174167c3ca072b37a45e9e4355d1c Author: Aaron Durbin adurbin@chromium.org Date: Mon Apr 29 16:57:10 2013 -0500
haswell: 24MHz monotonic time implementation
Haswell ULT devices have a 24MHz package-level counter. Use this counter to provide a time_monotonic_get() implementation.
Change-Id: Ic79843fcbfbbb6462ee5ebd12b39502307750dbb Signed-off-by: Aaron Durbin adurbin@chromium.org --- src/cpu/intel/haswell/Kconfig | 7 ++++ src/cpu/intel/haswell/Makefile.inc | 1 + src/cpu/intel/haswell/monotonic_timer.c | 62 +++++++++++++++++++++++++++++++++ 3 files changed, 70 insertions(+)
diff --git a/src/cpu/intel/haswell/Kconfig b/src/cpu/intel/haswell/Kconfig index 5f27d4c..13861f9 100644 --- a/src/cpu/intel/haswell/Kconfig +++ b/src/cpu/intel/haswell/Kconfig @@ -54,4 +54,11 @@ config RESET_ON_INVALID_RAMSTAGE_CACHE the system will reset otherwise the ramstage will be reloaded from cbfs.
+config MONOTONIC_TIMER_MSR + def_bool n + depends on INTEL_LYNXPOINT_LP + select HAVE_MONOTONIC_TIMER + help + Provide a monotonic timer using the 24MHz MSR counter. + endif diff --git a/src/cpu/intel/haswell/Makefile.inc b/src/cpu/intel/haswell/Makefile.inc index a19a8c5..90ffd66 100644 --- a/src/cpu/intel/haswell/Makefile.inc +++ b/src/cpu/intel/haswell/Makefile.inc @@ -5,6 +5,7 @@ romstage-y += romstage.c
ramstage-$(CONFIG_GENERATE_ACPI_TABLES) += acpi.c ramstage-$(CONFIG_HAVE_SMI_HANDLER) += smmrelocate.c +ramstage-$(CONFIG_MONOTONIC_TIMER_MSR) += monotonic_timer.c
cpu_microcode-$(CONFIG_CPU_MICROCODE_CBFS_GENERATE) += microcode_blob.c
diff --git a/src/cpu/intel/haswell/monotonic_timer.c b/src/cpu/intel/haswell/monotonic_timer.c new file mode 100644 index 0000000..c51bcbd --- /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 <stdint.h> +#include <cpu/x86/msr.h> +#include <timer.h> + +#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; +}
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Aaron Durbin