LXR linux/arch/microblaze/include/asm/delay.h

   1/*
   2 * include/asm-microblaze/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) 2008 Michal Simek
   9 * Copyright (C) 2007 John Williams
  10 * Copyright (C) 2006 Atmark Techno, Inc.
  11 */
  12
  13#ifndef _ASM_MICROBLAZE_DELAY_H
  14#define _ASM_MICROBLAZE_DELAY_H
  15
  16#include <linux/param.h>
  17
  18static inline void __delay(unsigned long loops)
  19{
  20        asm volatile ("# __delay                \n\t"           \
  21                        "1: addi        %0, %0, -1\t\n"         \
  22                        "bneid  %0, 1b          \t\n"           \
  23                        "nop                    \t\n"
  24                        : "=r" (loops)
  25                        : "0" (loops));
  26}
  27
  28/*
  29 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
  30 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
  31 *
  32 * The mul instruction gives us loops = (a * b) / 2^32.
  33 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
  34 * because this lets us support a wide range of HZ and
  35 * loops_per_jiffy values without either a or b overflowing 2^32.
  36 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
  37 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
  38 * (which corresponds to ~3800 bogomips at HZ = 100).
  39 * -- paulus
  40 */
  41#define __MAX_UDELAY    (226050910UL/HZ)        /* maximum udelay argument */
  42#define __MAX_NDELAY    (4294967295UL/HZ)       /* maximum ndelay argument */
  43
  44extern unsigned long loops_per_jiffy;
  45
  46static inline void __udelay(unsigned int x)
  47{
  48
  49        unsigned long long tmp =
  50                (unsigned long long)x * (unsigned long long)loops_per_jiffy \
  51                        * 226LL;
  52        unsigned loops = tmp >> 32;
  53
  54/*
  55        __asm__("mulxuu %0,%1,%2" : "=r" (loops) :
  56                "r" (x), "r" (loops_per_jiffy * 226));
  57*/
  58        __delay(loops);
  59}
  60
  61extern void __bad_udelay(void);         /* deliberately undefined */
  62extern void __bad_ndelay(void);         /* deliberately undefined */
  63
  64#define udelay(n)                                               \
  65        ({                                                      \
  66                if (__builtin_constant_p(n)) {                  \
  67                        if ((n) / __MAX_UDELAY >= 1)            \
  68                                __bad_udelay();                 \
  69                        else                                    \
  70                                __udelay((n) * (19 * HZ));      \
  71                } else {                                        \
  72                        __udelay((n) * (19 * HZ));              \
  73                }                                               \
  74        })
  75
  76#define ndelay(n)                                               \
  77        ({                                                      \
  78                if (__builtin_constant_p(n)) {                  \
  79                        if ((n) / __MAX_NDELAY >= 1)            \
  80                                __bad_ndelay();                 \
  81                        else                                    \
  82                                __udelay((n) * HZ);             \
  83                } else {                                        \
  84                        __udelay((n) * HZ);                     \
  85                }                                               \
  86        })
  87
  88#define muldiv(a, b, c)         (((a)*(b))/(c))
  89
  90#endif /* _ASM_MICROBLAZE_DELAY_H */
  91