From 0d6ddf8da7632e775dde92c9114ac6ace5ca5f14 Mon Sep 17 00:00:00 2001 From: Kyösti Mälkki Date: Thu, 31 Oct 2019 14:52:20 +0200 Subject: cpu/x86/tsc: Flip and rename TSC_CONSTANT_RATE to UNKNOWN_TSC_RATE MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-on: https://review.coreboot.org/c/coreboot/+/33928 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/cpu/x86/tsc/delay_tsc.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-) (limited to 'src/cpu/x86/tsc/delay_tsc.c') diff --git a/src/cpu/x86/tsc/delay_tsc.c b/src/cpu/x86/tsc/delay_tsc.c index afcd1d1f7d..7aa887ae63 100644 --- a/src/cpu/x86/tsc/delay_tsc.c +++ b/src/cpu/x86/tsc/delay_tsc.c @@ -18,26 +18,9 @@ #include #include -static unsigned long clocks_per_usec CAR_GLOBAL; - -static unsigned long calibrate_tsc(void) -{ - if (CONFIG(TSC_CONSTANT_RATE)) - return tsc_freq_mhz(); - else - return calibrate_tsc_with_pit(); -} - void init_timer(void) { - if (!car_get_var(clocks_per_usec)) - car_set_var(clocks_per_usec, calibrate_tsc()); -} - -static inline unsigned long get_clocks_per_usec(void) -{ - init_timer(); - return car_get_var(clocks_per_usec); + (void)tsc_freq_mhz(); } void udelay(unsigned int us) @@ -51,7 +34,7 @@ void udelay(unsigned int us) start = rdtscll(); clocks = us; - clocks *= get_clocks_per_usec(); + clocks *= tsc_freq_mhz(); current = rdtscll(); while ((current - start) < clocks) { cpu_relax(); @@ -89,7 +72,7 @@ void timer_monotonic_get(struct mono_time *mt) current_tick = rdtscll(); ticks_elapsed = current_tick - mono_counter->last_value; - ticks_per_usec = get_clocks_per_usec(); + ticks_per_usec = tsc_freq_mhz(); /* Update current time and tick values only if a full tick occurred. */ if (ticks_elapsed >= ticks_per_usec) { -- cgit v1.2.3