arch/sh/lib64/udelay.c

   1 /*
   2  * arch/sh/lib64/udelay.c
   3  *
   4  * Delay routines, using a pre-computed "loops_per_jiffy" value.
   5  *
   6  * Copyright (C) 2000, 2001  Paolo Alberelli
   7  * Copyright (C) 2003, 2004  Paul Mundt
   8  *
   9  * This file is subject to the terms and conditions of the GNU General Public
  10  * License.  See the file "COPYING" in the main directory of this archive
  11  * for more details.
  12  */
  13 #include <linux/sched.h>
  14 #include <asm/param.h>
  15
  16 /*
  17  * Use only for very small delays (< 1 msec).
  18  *
  19  * The active part of our cycle counter is only 32-bits wide, and
  20  * we're treating the difference between two marks as signed.  On
  21  * a 1GHz box, that's about 2 seconds.
  22  */
  23
  24 void __delay(unsigned long loops)
  25 {
  26         long long dummy;
  27         __asm__ __volatile__("gettr     tr0, %1\n\t"
  28                              "pta       $+4, tr0\n\t"
  29                              "addi      %0, -1, %0\n\t"
  30                              "bne       %0, r63, tr0\n\t"
  31                              "ptabs     %1, tr0\n\t":"=r"(loops),
  32                              "=r"(dummy)
  33                              :"0"(loops));
  34 }
  35
  36 inline void __const_udelay(unsigned long xloops)
  37 {
  38         __delay(xloops * (HZ * cpu_data[raw_smp_processor_id()].loops_per_jiffy));
  39 }
  40
  41 void __udelay(unsigned long usecs)
  42 {
  43         __const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
  44 }
  45
  46 void __ndelay(unsigned long nsecs)
  47 {
  48         __const_udelay(nsecs * 0x00000005);
  49 }