arch/powerpc/include/asm/delay.h

   1 #ifndef _ASM_POWERPC_DELAY_H
   2 #define _ASM_POWERPC_DELAY_H
   3 #ifdef __KERNEL__
   4
   5 #include <linux/processor.h>
   6 #include <asm/time.h>
   7
   8 /*
   9  * Copyright 1996, Paul Mackerras.
  10  * Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version
  15  * 2 of the License, or (at your option) any later version.
  16  *
  17  * PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan,
  18  * Anton Blanchard.
  19  */
  20
  21 extern void __delay(unsigned long loops);
  22 extern void udelay(unsigned long usecs);
  23
  24 /*
  25  * On shared processor machines the generic implementation of mdelay can
  26  * result in large errors. While each iteration of the loop inside mdelay
  27  * is supposed to take 1ms, the hypervisor could sleep our partition for
  28  * longer (eg 10ms). With the right timing these errors can add up.
  29  *
  30  * Since there is no 32bit overflow issue on 64bit kernels, just call
  31  * udelay directly.
  32  */
  33 #ifdef CONFIG_PPC64
  34 #define mdelay(n)       udelay((n) * 1000)
  35 #endif
  36
  37 /**
  38  * spin_event_timeout - spin until a condition gets true or a timeout elapses
  39  * @condition: a C expression to evalate
  40  * @timeout: timeout, in microseconds
  41  * @delay: the number of microseconds to delay between each evaluation of
  42  *         @condition
  43  *
  44  * The process spins until the condition evaluates to true (non-zero) or the
  45  * timeout elapses.  The return value of this macro is the value of
  46  * @condition when the loop terminates. This allows you to determine the cause
  47  * of the loop terminates.  If the return value is zero, then you know a
  48  * timeout has occurred.
  49  *
  50  * This primary purpose of this macro is to poll on a hardware register
  51  * until a status bit changes.  The timeout ensures that the loop still
  52  * terminates even if the bit never changes.  The delay is for devices that
  53  * need a delay in between successive reads.
  54  *
  55  * gcc will optimize out the if-statement if @delay is a constant.
  56  */
  57 #define spin_event_timeout(condition, timeout, delay)                          \
  58 ({                                                                             \
  59         typeof(condition) __ret;                                               \
  60         unsigned long __loops = tb_ticks_per_usec * timeout;                   \
  61         unsigned long __start = get_tbl();                                     \
  62                                                                                \
  63         if (delay) {                                                           \
  64                 while (!(__ret = (condition)) &&                               \
  65                                 (tb_ticks_since(__start) <= __loops))          \
  66                         udelay(delay);                                         \
  67         } else {                                                               \
  68                 spin_begin();                                                  \
  69                 while (!(__ret = (condition)) &&                               \
  70                                 (tb_ticks_since(__start) <= __loops))          \
  71                         spin_cpu_relax();                                      \
  72                 spin_end();                                                    \
  73         }                                                                      \
  74         if (!__ret)                                                            \
  75                 __ret = (condition);                                           \
  76         __ret;                                                                 \
  77 })
  78
  79 #endif /* __KERNEL__ */
  80 #endif /* _ASM_POWERPC_DELAY_H */