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lib/timestamp: Init TSC frequency early on x86

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When get_us_since_boot() is called in pre-ram stages on x86 init
the TSC frequency. The TSC frequency is necessary to calculate
the time spent since boot.

When get_us_since_boot() is not used in pre-ram stages the function
timestamp_tick_freq_mhz() will also be dropped by the linker, thus
there's no code size increase for common code.

Will be used in the following commit in pre-ram stages.

Change-Id: I7fd9eeadf3063a629dd589498fcb957b9bd66536
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88793
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
This commit is contained in:
Patrick Rudolph 2025-08-16 15:15:43 +02:00 • committed by Matt DeVillier
commit 3b2962929b
1 changed files with 10 additions and 0 deletions
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10
src/lib/timestamp.c
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@ -274,6 +274,16 @@ uint32_t get_us_since_boot(void)
{
struct timestamp_table *ts = timestamp_table_get();
/*
* Bootbock size is limited on some platforms, thus only
* enable get_us_since_boot() in PRERAM stages on x86 platforms
* for now. When get_us_since_boot() isn't used in preram the linker
* will drop timestamp_tick_freq_mhz().
*/
if (CONFIG(ARCH_X86) && ENV_ROMSTAGE_OR_BEFORE &&
ts && ts->tick_freq_mhz == 0)
ts->tick_freq_mhz = timestamp_tick_freq_mhz();
if (ts == NULL || ts->tick_freq_mhz == 0)
return 0;
return (timestamp_get() - ts->base_time) / ts->tick_freq_mhz;