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