arch/powerpc/include/asm/delay.h

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