LXR linux/arch/cris/arch-v32/lib/delay.c

   1/*
   2 * Precise Delay Loops for ETRAX FS
   3 *
   4 * Copyright (C) 2006 Axis Communications AB.
   5 *
   6 */
   7
   8#include <hwregs/reg_map.h>
   9#include <hwregs/reg_rdwr.h>
  10#include <hwregs/timer_defs.h>
  11#include <linux/types.h>
  12#include <linux/delay.h>
  13#include <linux/module.h>
  14
  15/*
  16 * On ETRAX FS, we can check the free-running read-only 100MHz timer
  17 * getting 32-bit 10ns precision, theoretically good for 42.94967295
  18 * seconds.  Unsigned arithmetic and careful expression handles
  19 * wrapping.
  20 */
  21
  22void cris_delay10ns(u32 n10ns)
  23{
  24        u32 t0 = REG_RD(timer, regi_timer0, r_time);
  25        while (REG_RD(timer, regi_timer0, r_time) - t0 < n10ns)
  26                ;
  27}
  28EXPORT_SYMBOL(cris_delay10ns);
  29