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| author | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2019-10-31 14:52:20 +0200 |
|---|---|---|
| committer | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2019-11-03 06:15:35 +0000 |
| commit | 0d6ddf8da7632e775dde92c9114ac6ace5ca5f14 (patch) | |
| tree | 67b37afc2c6bc3cfaa3750a87394c5b056067137 /src/include/cpu | |
| parent | ea2bec2c4b1a986b059147506c99a202d5c8fad3 (diff) | |
cpu/x86/tsc: Flip and rename TSC_CONSTANT_RATE to UNKNOWN_TSC_RATE
The x86 timers are a bit of a mess. Cases where different stages use
different counters and timestamps use different counters from udelays.
The original intention was to only flip TSC_CONSTANT_RATE Kconfig
to NOT_CONSTANT_TSC_RATE. The name would be incorrect though, those
counters do run with a constant rate but we just lack tsc_freq_mhz()
implementation for three platforms.
Note that for boards with UNKNOWN_TSC_RATE=y, each stage will have a
slow run of calibrate_tsc_with_pit(). This is easy enough to fix with
followup implementation of tsc_freq_mhz() for the platforms.
Implementations with LAPIC_MONOTONIC_TIMER typically will not have
tsc_freq_mhz() implemented and default to UNKNOWN_TSC_RATE. However,
as they don't use TSC for udelay() the slow calibrate_tsc_with_pit()
is avoided.
Because x86/tsc_delay.tsc was using two different guards and nb/via/vx900
claimed UDELAY_TSC, but pulled UDELAY_IO implementation, we also switch
that romstage to use UDELAY_TSC.
Change-Id: I1690cb80295d6b006b75ed69edea28899b674b68
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33928
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Diffstat (limited to 'src/include/cpu')
| -rw-r--r-- | src/include/cpu/x86/tsc.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/include/cpu/x86/tsc.h b/src/include/cpu/x86/tsc.h index dd333e8930..c18f8782f0 100644 --- a/src/include/cpu/x86/tsc.h +++ b/src/include/cpu/x86/tsc.h @@ -63,4 +63,9 @@ static inline uint64_t tsc_to_uint64(tsc_t tstamp) /* Provided by CPU/chipset code for the TSC rate in MHz. */ unsigned long tsc_freq_mhz(void); +static inline int tsc_constant_rate(void) +{ + return !CONFIG(UNKNOWN_TSC_RATE); +} + #endif /* CPU_X86_TSC_H */ |