include/asm-generic/qspinlock_types.h

   1 /*
   2  * Queued spinlock
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
  15  *
  16  * Authors: Waiman Long <waiman.long@hp.com>
  17  */
  18 #ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H
  19 #define __ASM_GENERIC_QSPINLOCK_TYPES_H
  20
  21 /*
  22  * Including atomic.h with PARAVIRT on will cause compilation errors because
  23  * of recursive header file incluson via paravirt_types.h. So don't include
  24  * it if PARAVIRT is on.
  25  */
  26 #ifndef CONFIG_PARAVIRT
  27 #include <linux/types.h>
  28 #include <linux/atomic.h>
  29 #endif
  30
  31 typedef struct qspinlock {
  32         atomic_t        val;
  33 } arch_spinlock_t;
  34
  35 /*
  36  * Bitfields in the atomic value:
  37  *
  38  * When NR_CPUS < 16K
  39  *  0- 7: locked byte
  40  *     8: pending
  41  *  9-15: not used
  42  * 16-17: tail index
  43  * 18-31: tail cpu (+1)
  44  *
  45  * When NR_CPUS >= 16K
  46  *  0- 7: locked byte
  47  *     8: pending
  48  *  9-10: tail index
  49  * 11-31: tail cpu (+1)
  50  */
  51 #define _Q_SET_MASK(type)       (((1U << _Q_ ## type ## _BITS) - 1)\
  52                                       << _Q_ ## type ## _OFFSET)
  53 #define _Q_LOCKED_OFFSET        0
  54 #define _Q_LOCKED_BITS          8
  55 #define _Q_LOCKED_MASK          _Q_SET_MASK(LOCKED)
  56
  57 #define _Q_PENDING_OFFSET       (_Q_LOCKED_OFFSET + _Q_LOCKED_BITS)
  58 #if CONFIG_NR_CPUS < (1U << 14)
  59 #define _Q_PENDING_BITS         8
  60 #else
  61 #define _Q_PENDING_BITS         1
  62 #endif
  63 #define _Q_PENDING_MASK         _Q_SET_MASK(PENDING)
  64
  65 #define _Q_TAIL_IDX_OFFSET      (_Q_PENDING_OFFSET + _Q_PENDING_BITS)
  66 #define _Q_TAIL_IDX_BITS        2
  67 #define _Q_TAIL_IDX_MASK        _Q_SET_MASK(TAIL_IDX)
  68
  69 #define _Q_TAIL_CPU_OFFSET      (_Q_TAIL_IDX_OFFSET + _Q_TAIL_IDX_BITS)
  70 #define _Q_TAIL_CPU_BITS        (32 - _Q_TAIL_CPU_OFFSET)
  71 #define _Q_TAIL_CPU_MASK        _Q_SET_MASK(TAIL_CPU)
  72
  73 #define _Q_TAIL_OFFSET          _Q_TAIL_IDX_OFFSET
  74 #define _Q_TAIL_MASK            (_Q_TAIL_IDX_MASK | _Q_TAIL_CPU_MASK)
  75
  76 #define _Q_LOCKED_VAL           (1U << _Q_LOCKED_OFFSET)
  77 #define _Q_PENDING_VAL          (1U << _Q_PENDING_OFFSET)
  78
  79 #endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */