LXR linux/arch/xtensa/variants/s6000/delay.c

   1#include <asm/delay.h>
   2#include <asm/timex.h>
   3#include <asm/io.h>
   4#include <variant/hardware.h>
   5
   6#define LOOPS 10
   7void platform_calibrate_ccount(void)
   8{
   9        u32 uninitialized_var(a);
  10        u32 uninitialized_var(u);
  11        u32 b;
  12        u32 tstamp = S6_REG_GREG1 + S6_GREG1_GLOBAL_TIMER;
  13        int i = LOOPS+1;
  14        do {
  15                u32 t = u;
  16                asm volatile(
  17                "1:     l32i %0, %2, 0 ;"
  18                "       beq %0, %1, 1b ;"
  19                : "=&a"(u) : "a"(t), "a"(tstamp));
  20                b = xtensa_get_ccount();
  21                if (i == LOOPS)
  22                        a = b;
  23        } while (--i >= 0);
  24        b -= a;
  25        nsec_per_ccount = (LOOPS * 10000) / b;
  26        ccount_per_jiffy = b * (100000UL / (LOOPS * HZ));
  27}
  28