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authorAaron Durbin <adurbin@chromium.org>2016-02-10 11:01:49 -0600
committerMartin Roth <martinroth@google.com>2016-02-19 19:50:25 +0100
commit152e5a03a130cea3009685cbf7eb0ea354d9fd1c (patch)
treed84669468988416d9d37f15c54d5db3343363cd5 /payloads/libpayload/libc
parente0969aec2573872b9f528e33edd2cf3fb84c5948 (diff)
downloadcoreboot-152e5a03a130cea3009685cbf7eb0ea354d9fd1c.tar.xz
libpayload: honor TSC information under CONFIG_LP_TIMER_RDTSC
When CONFIG_LP_TIMER_RDTSC is enabled honor the TSC information exported in the coreboot tables as the cpu_khz frequency. That allows get_cpu_speed() not to be called which currently relies on the 8254 PIT. As certain x86 platforms allow that device to be optional or turned off for power saving reasons, allow a path where get_cpu_speed() is no longer called. Additionally, this approach also allows the libpayload to not duplicate logic that already exists in coreboot. BUG=chrome-os-partner:50214 BRANCH=glados TEST=Confirmed in payload TSC frequency is honored instead of using get_cpu_speed(). Change-Id: Ib8993afdfb49065d43de705d6dbbdb9174b6f2c4 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/13671 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com> Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
Diffstat (limited to 'payloads/libpayload/libc')
-rw-r--r--payloads/libpayload/libc/coreboot.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/payloads/libpayload/libc/coreboot.c b/payloads/libpayload/libc/coreboot.c
index 3e248e19c3..3abd610be2 100644
--- a/payloads/libpayload/libc/coreboot.c
+++ b/payloads/libpayload/libc/coreboot.c
@@ -231,6 +231,19 @@ static void cb_parse_boot_media_params(unsigned char *ptr,
info->boot_media_size = bmp->boot_media_size;
}
+#if IS_ENABLED(CONFIG_LP_TIMER_RDTSC)
+static void cb_parse_tsc_info(void *ptr, struct sysinfo_t *info)
+{
+ const struct cb_tsc_info *tsc_info = ptr;
+
+ if (tsc_info->freq_khz == 0)
+ return;
+
+ /* Honor the TSC frequency passed to the payload. */
+ info->cpu_khz = tsc_info->freq_khz;
+}
+#endif
+
int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
{
struct cb_header *header;
@@ -386,6 +399,11 @@ int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
case CB_TAG_BOOT_MEDIA_PARAMS:
cb_parse_boot_media_params(ptr, info);
break;
+#if IS_ENABLED(CONFIG_LP_TIMER_RDTSC)
+ case CB_TAG_TSC_INFO:
+ cb_parse_tsc_info(ptr, info);
+ break;
+#endif
default:
cb_parse_arch_specific(rec, info);
break;