delay.c

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#include <asm/delay.h>
#include <asm/timex.h>
#include <asm/io.h>
#include <variant/hardware.h>

#define LOOPS 10
void platform_calibrate_ccount(void)
{
    u32 uninitialized_var(a);
    u32 uninitialized_var(u);
    u32 b;
    u32 tstamp = S6_REG_GREG1 + S6_GREG1_GLOBAL_TIMER;
    int i = LOOPS+1;
    do {
        u32 t = u;
        asm volatile(
        "1: l32i %0, %2, 0 ;"
        "   beq %0, %1, 1b ;"
        : "=&a"(u) : "a"(t), "a"(tstamp));
        b = xtensa_get_ccount();
        if (i == LOOPS)
            a = b;
    } while (--i >= 0);
    b -= a;
    nsec_per_ccount = (LOOPS * 10000) / b;
    ccount_per_jiffy = b * (100000UL / (LOOPS * HZ));
}