arch/sh/lib/delay.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      Precise Delay Loops for SuperH
   4  *
   5  *      Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
   6  */
   7
   8 #include <linux/sched.h>
   9 #include <linux/delay.h>
  10
  11 void __delay(unsigned long loops)
  12 {
  13         __asm__ __volatile__(
  14                 /*
  15                  * ST40-300 appears to have an issue with this code,
  16                  * normally taking two cycles each loop, as with all
  17                  * other SH variants. If however the branch and the
  18                  * delay slot straddle an 8 byte boundary, this increases
  19                  * to 3 cycles.
  20                  * This align directive ensures this doesn't occur.
  21                  */
  22                 ".balign 8\n\t"
  23
  24                 "tst    %0, %0\n\t"
  25                 "1:\t"
  26                 "bf/s   1b\n\t"
  27                 " dt    %0"
  28                 : "=r" (loops)
  29                 : "0" (loops)
  30                 : "t");
  31 }
  32
  33 inline void __const_udelay(unsigned long xloops)
  34 {
  35         xloops *= 4;
  36         __asm__("dmulu.l        %0, %2\n\t"
  37                 "sts    mach, %0"
  38                 : "=r" (xloops)
  39                 : "0" (xloops),
  40                   "r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
  41                 : "macl", "mach");
  42         __delay(++xloops);
  43 }
  44
  45 void __udelay(unsigned long usecs)
  46 {
  47         __const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
  48 }
  49
  50 void __ndelay(unsigned long nsecs)
  51 {
  52         __const_udelay(nsecs * 0x00000005);
  53 }
  54