arch/sh/lib/delay.c

   1 /*
   2  *      Precise Delay Loops for SuperH
   3  *
   4  *      Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
   5  */
   6
   7 #include <linux/sched.h>
   8 #include <linux/delay.h>
   9
  10 void __delay(unsigned long loops)
  11 {
  12         __asm__ __volatile__(
  13                 /*
  14                  * ST40-300 appears to have an issue with this code,
  15                  * normally taking two cycles each loop, as with all
  16                  * other SH variants. If however the branch and the
  17                  * delay slot straddle an 8 byte boundary, this increases
  18                  * to 3 cycles.
  19                  * This align directive ensures this doesn't occur.
  20                  */
  21                 ".balign 8\n\t"
  22
  23                 "tst    %0, %0\n\t"
  24                 "1:\t"
  25                 "bf/s   1b\n\t"
  26                 " dt    %0"
  27                 : "=r" (loops)
  28                 : "0" (loops)
  29                 : "t");
  30 }
  31
  32 inline void __const_udelay(unsigned long xloops)
  33 {
  34         xloops *= 4;
  35         __asm__("dmulu.l        %0, %2\n\t"
  36                 "sts    mach, %0"
  37                 : "=r" (xloops)
  38                 : "0" (xloops),
  39                   "r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
  40                 : "macl", "mach");
  41         __delay(++xloops);
  42 }
  43
  44 void __udelay(unsigned long usecs)
  45 {
  46         __const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
  47 }
  48
  49 void __ndelay(unsigned long nsecs)
  50 {
  51         __const_udelay(nsecs * 0x00000005);
  52 }
  53