arch/xtensa/include/asm/delay.h

   1 /*
   2  * include/asm-xtensa/delay.h
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2001 - 2005 Tensilica Inc.
   9  *
  10  */
  11
  12 #ifndef _XTENSA_DELAY_H
  13 #define _XTENSA_DELAY_H
  14
  15 #include <asm/timex.h>
  16 #include <asm/param.h>
  17
  18 extern unsigned long loops_per_jiffy;
  19
  20 static inline void __delay(unsigned long loops)
  21 {
  22         if (__builtin_constant_p(loops) && loops < 2)
  23                 __asm__ __volatile__ ("nop");
  24         else if (loops >= 2)
  25                 /* 2 cycles per loop. */
  26                 __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
  27                                 : "+r" (loops));
  28 }
  29
  30 /* Undefined function to get compile-time error */
  31 void __bad_udelay(void);
  32 void __bad_ndelay(void);
  33
  34 #define __MAX_UDELAY 30000
  35 #define __MAX_NDELAY 30000
  36
  37 static inline void __udelay(unsigned long usecs)
  38 {
  39         unsigned long start = get_ccount();
  40         unsigned long cycles = (usecs * (ccount_freq >> 15)) >> 5;
  41
  42         /* Note: all variables are unsigned (can wrap around)! */
  43         while (((unsigned long)get_ccount()) - start < cycles)
  44                 cpu_relax();
  45 }
  46
  47 static inline void udelay(unsigned long usec)
  48 {
  49         if (__builtin_constant_p(usec) && usec >= __MAX_UDELAY)
  50                 __bad_udelay();
  51         else
  52                 __udelay(usec);
  53 }
  54
  55 static inline void __ndelay(unsigned long nsec)
  56 {
  57         /*
  58          * Inner shift makes sure multiplication doesn't overflow
  59          * for legitimate nsec values
  60          */
  61         unsigned long cycles = (nsec * (ccount_freq >> 15)) >> 15;
  62         __delay(cycles);
  63 }
  64
  65 #define ndelay(n) ndelay(n)
  66
  67 static inline void ndelay(unsigned long nsec)
  68 {
  69         if (__builtin_constant_p(nsec) && nsec >= __MAX_NDELAY)
  70                 __bad_ndelay();
  71         else
  72                 __ndelay(nsec);
  73 }
  74
  75 #endif