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

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Copyright (C) 2008 Michal Simek
   4 * Copyright (C) 2007 John Williams
   5 * Copyright (C) 2006 Atmark Techno, Inc.
   6 */
   7
   8#ifndef _ASM_MICROBLAZE_DELAY_H
   9#define _ASM_MICROBLAZE_DELAY_H
  10
  11#include <linux/param.h>
  12
  13static inline void __delay(unsigned long loops)
  14{
  15        asm volatile ("# __delay                \n\t"           \
  16                        "1: addi        %0, %0, -1\t\n"         \
  17                        "bneid  %0, 1b          \t\n"           \
  18                        "nop                    \t\n"
  19                        : "=r" (loops)
  20                        : "0" (loops));
  21}
  22
  23/*
  24 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
  25 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
  26 *
  27 * The mul instruction gives us loops = (a * b) / 2^32.
  28 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
  29 * because this lets us support a wide range of HZ and
  30 * loops_per_jiffy values without either a or b overflowing 2^32.
  31 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
  32 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
  33 * (which corresponds to ~3800 bogomips at HZ = 100).
  34 * -- paulus
  35 */
  36#define __MAX_UDELAY    (226050910UL/HZ)        /* maximum udelay argument */
  37#define __MAX_NDELAY    (4294967295UL/HZ)       /* maximum ndelay argument */
  38
  39extern unsigned long loops_per_jiffy;
  40
  41static inline void __udelay(unsigned int x)
  42{
  43
  44        unsigned long long tmp =
  45                (unsigned long long)x * (unsigned long long)loops_per_jiffy \
  46                        * 226LL;
  47        unsigned loops = tmp >> 32;
  48
  49/*
  50        __asm__("mulxuu %0,%1,%2" : "=r" (loops) :
  51                "r" (x), "r" (loops_per_jiffy * 226));
  52*/
  53        __delay(loops);
  54}
  55
  56extern void __bad_udelay(void);         /* deliberately undefined */
  57extern void __bad_ndelay(void);         /* deliberately undefined */
  58
  59#define udelay(n)                                               \
  60        ({                                                      \
  61                if (__builtin_constant_p(n)) {                  \
  62                        if ((n) / __MAX_UDELAY >= 1)            \
  63                                __bad_udelay();                 \
  64                        else                                    \
  65                                __udelay((n) * (19 * HZ));      \
  66                } else {                                        \
  67                        __udelay((n) * (19 * HZ));              \
  68                }                                               \
  69        })
  70
  71#define ndelay(n)                                               \
  72        ({                                                      \
  73                if (__builtin_constant_p(n)) {                  \
  74                        if ((n) / __MAX_NDELAY >= 1)            \
  75                                __bad_ndelay();                 \
  76                        else                                    \
  77                                __udelay((n) * HZ);             \
  78                } else {                                        \
  79                        __udelay((n) * HZ);                     \
  80                }                                               \
  81        })
  82
  83#define muldiv(a, b, c)         (((a)*(b))/(c))
  84
  85#endif /* _ASM_MICROBLAZE_DELAY_H */
  86