/*
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* Queued spinlock
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
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*
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* Authors: Waiman Long <waiman.long@hp.com>
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*/
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#ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H
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#define __ASM_GENERIC_QSPINLOCK_TYPES_H
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/*
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* Including atomic.h with PARAVIRT on will cause compilation errors because
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* of recursive header file incluson via paravirt_types.h. So don't include
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* it if PARAVIRT is on.
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*/
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#ifndef CONFIG_PARAVIRT
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#include <linux/types.h>
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#include <linux/atomic.h>
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#endif
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typedef struct qspinlock {
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union {
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atomic_t val;
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/*
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* By using the whole 2nd least significant byte for the
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* pending bit, we can allow better optimization of the lock
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* acquisition for the pending bit holder.
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*/
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#ifdef __LITTLE_ENDIAN
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struct {
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u8 locked;
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u8 pending;
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};
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struct {
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u16 locked_pending;
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u16 tail;
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};
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#else
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struct {
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u16 tail;
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u16 locked_pending;
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};
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struct {
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u8 reserved[2];
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u8 pending;
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u8 locked;
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};
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#endif
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};
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} arch_spinlock_t;
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/*
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* Initializier
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*/
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#define __ARCH_SPIN_LOCK_UNLOCKED { { .val = ATOMIC_INIT(0) } }
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/*
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* Bitfields in the atomic value:
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*
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* When NR_CPUS < 16K
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* 0- 7: locked byte
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* 8: pending
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* 9-15: not used
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* 16-17: tail index
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* 18-31: tail cpu (+1)
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*
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* When NR_CPUS >= 16K
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* 0- 7: locked byte
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* 8: pending
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* 9-10: tail index
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* 11-31: tail cpu (+1)
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*/
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#define _Q_SET_MASK(type) (((1U << _Q_ ## type ## _BITS) - 1)\
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<< _Q_ ## type ## _OFFSET)
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#define _Q_LOCKED_OFFSET 0
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#define _Q_LOCKED_BITS 8
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#define _Q_LOCKED_MASK _Q_SET_MASK(LOCKED)
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#define _Q_PENDING_OFFSET (_Q_LOCKED_OFFSET + _Q_LOCKED_BITS)
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#if CONFIG_NR_CPUS < (1U << 14)
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#define _Q_PENDING_BITS 8
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#else
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#define _Q_PENDING_BITS 1
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#endif
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#define _Q_PENDING_MASK _Q_SET_MASK(PENDING)
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#define _Q_TAIL_IDX_OFFSET (_Q_PENDING_OFFSET + _Q_PENDING_BITS)
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#define _Q_TAIL_IDX_BITS 2
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#define _Q_TAIL_IDX_MASK _Q_SET_MASK(TAIL_IDX)
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#define _Q_TAIL_CPU_OFFSET (_Q_TAIL_IDX_OFFSET + _Q_TAIL_IDX_BITS)
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#define _Q_TAIL_CPU_BITS (32 - _Q_TAIL_CPU_OFFSET)
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#define _Q_TAIL_CPU_MASK _Q_SET_MASK(TAIL_CPU)
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#define _Q_TAIL_OFFSET _Q_TAIL_IDX_OFFSET
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#define _Q_TAIL_MASK (_Q_TAIL_IDX_MASK | _Q_TAIL_CPU_MASK)
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#define _Q_LOCKED_VAL (1U << _Q_LOCKED_OFFSET)
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#define _Q_PENDING_VAL (1U << _Q_PENDING_OFFSET)
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#endif /* __ASM_GENERIC_QSPINLOCK_TYPES_H */
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