include/asm-mips/delay.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 by Waldorf Electronics
   7  * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  * Copyright (C) 2007  Maciej W. Rozycki
  10  */
  11 #ifndef _ASM_DELAY_H
  12 #define _ASM_DELAY_H
  13
  14 #include <linux/param.h>
  15 #include <linux/smp.h>
  16
  17 #include <asm/compiler.h>
  18 #include <asm/war.h>
  19
  20 static inline void __delay(unsigned long loops)
  21 {
  22         if (sizeof(long) == 4)
  23                 __asm__ __volatile__ (
  24                 "       .set    noreorder                               \n"
  25                 "       .align  3                                       \n"
  26                 "1:     bnez    %0, 1b                                  \n"
  27                 "       subu    %0, 1                                   \n"
  28                 "       .set    reorder                                 \n"
  29                 : "=r" (loops)
  30                 : "0" (loops));
  31         else if (sizeof(long) == 8 && !DADDI_WAR)
  32                 __asm__ __volatile__ (
  33                 "       .set    noreorder                               \n"
  34                 "       .align  3                                       \n"
  35                 "1:     bnez    %0, 1b                                  \n"
  36                 "       dsubu   %0, 1                                   \n"
  37                 "       .set    reorder                                 \n"
  38                 : "=r" (loops)
  39                 : "0" (loops));
  40         else if (sizeof(long) == 8 && DADDI_WAR)
  41                 __asm__ __volatile__ (
  42                 "       .set    noreorder                               \n"
  43                 "       .align  3                                       \n"
  44                 "1:     bnez    %0, 1b                                  \n"
  45                 "       dsubu   %0, %2                                  \n"
  46                 "       .set    reorder                                 \n"
  47                 : "=r" (loops)
  48                 : "0" (loops), "r" (1));
  49 }
  50
  51
  52 /*
  53  * Division by multiplication: you don't have to worry about
  54  * loss of precision.
  55  *
  56  * Use only for very small delays ( < 1 msec).  Should probably use a
  57  * lookup table, really, as the multiplications take much too long with
  58  * short delays.  This is a "reasonable" implementation, though (and the
  59  * first constant multiplications gets optimized away if the delay is
  60  * a constant)
  61  */
  62
  63 static inline void __udelay(unsigned long usecs, unsigned long lpj)
  64 {
  65         unsigned long hi, lo;
  66
  67         /*
  68          * The rates of 128 is rounded wrongly by the catchall case
  69          * for 64-bit.  Excessive precission?  Probably ...
  70          */
  71 #if defined(CONFIG_64BIT) && (HZ == 128)
  72         usecs *= 0x0008637bd05af6c7UL;          /* 2**64 / (1000000 / HZ) */
  73 #elif defined(CONFIG_64BIT)
  74         usecs *= (0x8000000000000000UL / (500000 / HZ));
  75 #else /* 32-bit junk follows here */
  76         usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) +
  77                                    0x80000000ULL) >> 32);
  78 #endif
  79
  80         if (sizeof(long) == 4)
  81                 __asm__("multu\t%2, %3"
  82                 : "=h" (usecs), "=l" (lo)
  83                 : "r" (usecs), "r" (lpj)
  84                 : GCC_REG_ACCUM);
  85         else if (sizeof(long) == 8 && !R4000_WAR)
  86                 __asm__("dmultu\t%2, %3"
  87                 : "=h" (usecs), "=l" (lo)
  88                 : "r" (usecs), "r" (lpj)
  89                 : GCC_REG_ACCUM);
  90         else if (sizeof(long) == 8 && R4000_WAR)
  91                 __asm__("dmultu\t%3, %4\n\tmfhi\t%0"
  92                 : "=r" (usecs), "=h" (hi), "=l" (lo)
  93                 : "r" (usecs), "r" (lpj)
  94                 : GCC_REG_ACCUM);
  95
  96         __delay(usecs);
  97 }
  98
  99 #define __udelay_val cpu_data[raw_smp_processor_id()].udelay_val
 100
 101 #define udelay(usecs) __udelay((usecs), __udelay_val)
 102
 103 /* make sure "usecs *= ..." in udelay do not overflow. */
 104 #if HZ >= 1000
 105 #define MAX_UDELAY_MS   1
 106 #elif HZ <= 200
 107 #define MAX_UDELAY_MS   5
 108 #else
 109 #define MAX_UDELAY_MS   (1000 / HZ)
 110 #endif
 111
 112 #endif /* _ASM_DELAY_H */