src/cpu/x86/tsc/delay_tsc.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <cpu/cpu.h>
   4 #include <cpu/x86/tsc.h>
   5 #include <delay.h>
   6 #include <stdint.h>
   7 #include <thread.h>
   8
   9 void init_timer(void)
  10 {
  11         (void)tsc_freq_mhz();
  12 }
  13
  14 void udelay(unsigned int us)
  15 {
  16         unsigned long long start;
  17         unsigned long long current;
  18         unsigned long long clocks;
  19
  20         if (!thread_yield_microseconds(us))
  21                 return;
  22
  23         start = rdtscll();
  24         clocks = us;
  25         clocks *= tsc_freq_mhz();
  26         current = rdtscll();
  27         while ((current - start) < clocks) {
  28                 cpu_relax();
  29                 current = rdtscll();
  30         }
  31 }
  32
  33 #if CONFIG(TSC_MONOTONIC_TIMER)
  34 #include <timer.h>
  35
  36 static struct monotonic_counter {
  37         int initialized;
  38         struct mono_time time;
  39         uint64_t last_value;
  40 } mono_counter;
  41
  42 void timer_monotonic_get(struct mono_time *mt)
  43 {
  44         uint64_t current_tick;
  45         uint64_t ticks_elapsed;
  46         unsigned long ticks_per_usec;
  47
  48         if (!mono_counter.initialized) {
  49                 init_timer();
  50                 mono_counter.last_value = rdtscll();
  51                 mono_counter.initialized = 1;
  52         }
  53
  54         current_tick = rdtscll();
  55         ticks_elapsed = current_tick - mono_counter.last_value;
  56         ticks_per_usec = tsc_freq_mhz();
  57
  58         /* Update current time and tick values only if a full tick occurred. */
  59         if (ticks_elapsed >= ticks_per_usec) {
  60                 uint64_t usecs_elapsed;
  61
  62                 usecs_elapsed = ticks_elapsed / ticks_per_usec;
  63                 mono_time_add_usecs(&mono_counter.time, (long)usecs_elapsed);
  64                 mono_counter.last_value = current_tick;
  65         }
  66
  67         /* Save result. */
  68         *mt = mono_counter.time;
  69 }
  70 #endif