arch_timer.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <timer.h>
#include <delay.h>
#include <cpu/power/spr.h>
 
/* Refer to hostboot/src/kernel/timemgr.C */
 
/* Time base frequency is 512 MHz so 512 ticks per usec */
#define TB_TICKS_PER_USEC 512
 
__weak void init_timer(void) { /* do nothing */ }
 
static struct monotonic_counter {
        int initialized;
        struct mono_time time;
        uint64_t last_value;
} mono_counter;
 
void timer_monotonic_get(struct mono_time *mt)
{
        uint64_t current_tick;
        uint64_t usecs_elapsed;
 
        if (!mono_counter.initialized) {
                mono_counter.last_value = read_spr(SPR_TB);
                mono_counter.initialized = 1;
        }
 
        current_tick = read_spr(SPR_TB);
        usecs_elapsed = (current_tick - mono_counter.last_value) / TB_TICKS_PER_USEC;
 
        /* Update current time and tick values only if a full tick occurred. */
        if (usecs_elapsed) {
                mono_time_add_usecs(&mono_counter.time, usecs_elapsed);
                mono_counter.last_value = current_tick;
        }
 
        /* Save result. */
        *mt = mono_counter.time;
}