/*
* Spinlock support for the Hexagon architecture
*
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/

#ifndef _ASM_SPINLOCK_H
#define _ASM_SPINLOCK_H

#include <asm/irqflags.h>

/*
* This file is pulled in for SMP builds.
* Really need to check all the barrier stuff for "true" SMP
*/

/*
* Read locks:
* - load the lock value
* - increment it
* - if the lock value is still negative, go back and try again.
* - unsuccessful store is unsuccessful. Go back and try again. Loser.
* - successful store new lock value if positive -> lock acquired
*/
static inline void arch_read_lock(arch_rwlock_t *lock)
{
__asm__ __volatile__(
"1: R6 = memw_locked(%0);\n"
" { P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
" { if !P3 jump 1b; }\n"
" memw_locked(%0,P3) = R6;\n"
" { if !P3 jump 1b; }\n"
:
: "r" (&lock->lock)
: "memory", "r6", "p3"
);

}

static inline void arch_read_unlock(arch_rwlock_t *lock)
{
__asm__ __volatile__(
"1: R6 = memw_locked(%0);\n"
" R6 = add(R6,#-1);\n"
" memw_locked(%0,P3) = R6\n"
" if !P3 jump 1b;\n"
:
: "r" (&lock->lock)
: "memory", "r6", "p3"
);

}

/* I think this returns 0 on fail, 1 on success. */
static inline int arch_read_trylock(arch_rwlock_t *lock)
{
int temp;
__asm__ __volatile__(
" R6 = memw_locked(%1);\n"
" { %0 = #0; P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
" { if !P3 jump 1f; }\n"
" memw_locked(%1,P3) = R6;\n"
" { %0 = P3 }\n"
"1:\n"
: "=&r" (temp)
: "r" (&lock->lock)
: "memory", "r6", "p3"
);
return temp;
}

static inline int arch_read_can_lock(arch_rwlock_t *rwlock)
{
return rwlock->lock == 0;
}

static inline int arch_write_can_lock(arch_rwlock_t *rwlock)
{
return rwlock->lock == 0;
}

/* Stuffs a -1 in the lock value? */
static inline void arch_write_lock(arch_rwlock_t *lock)
{
__asm__ __volatile__(
"1: R6 = memw_locked(%0)\n"
" { P3 = cmp.eq(R6,#0); R6 = #-1;}\n"
" { if !P3 jump 1b; }\n"
" memw_locked(%0,P3) = R6;\n"
" { if !P3 jump 1b; }\n"
:
: "r" (&lock->lock)
: "memory", "r6", "p3"
);
}


static inline int arch_write_trylock(arch_rwlock_t *lock)
{
int temp;
__asm__ __volatile__(
" R6 = memw_locked(%1)\n"
" { %0 = #0; P3 = cmp.eq(R6,#0); R6 = #-1;}\n"
" { if !P3 jump 1f; }\n"
" memw_locked(%1,P3) = R6;\n"
" %0 = P3;\n"
"1:\n"
: "=&r" (temp)
: "r" (&lock->lock)
: "memory", "r6", "p3"
);
return temp;

}

static inline void arch_write_unlock(arch_rwlock_t *lock)
{
smp_mb();
lock->lock = 0;
}

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
__asm__ __volatile__(
"1: R6 = memw_locked(%0);\n"
" P3 = cmp.eq(R6,#0);\n"
" { if !P3 jump 1b; R6 = #1; }\n"
" memw_locked(%0,P3) = R6;\n"
" { if !P3 jump 1b; }\n"
:
: "r" (&lock->lock)
: "memory", "r6", "p3"
);

}

static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
smp_mb();
lock->lock = 0;
}

static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
{
int temp;
__asm__ __volatile__(
" R6 = memw_locked(%1);\n"
" P3 = cmp.eq(R6,#0);\n"
" { if !P3 jump 1f; R6 = #1; %0 = #0; }\n"
" memw_locked(%1,P3) = R6;\n"
" %0 = P3;\n"
"1:\n"
: "=&r" (temp)
: "r" (&lock->lock)
: "memory", "r6", "p3"
);
return temp;
}

/*
* SMP spinlocks are intended to allow only a single CPU at the lock
*/
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(lock) \
do {while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
#define arch_spin_is_locked(x) ((x)->lock != 0)

#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)

#endif