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
  13 static 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
  39 extern unsigned long loops_per_jiffy;
  40
  41 static 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
  56 extern void __bad_udelay(void);         /* deliberately undefined */
  57 extern 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 */