2 * include/asm-sh/spinlock.h
4 * Copyright (C) 2002, 2003 Paul Mundt
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
10 #ifndef __ASM_SH_SPINLOCK_H
11 #define __ASM_SH_SPINLOCK_H
13 #include <asm/atomic.h>
14 #include <asm/spinlock_types.h>
17 * Your basic SMP spinlocks, allowing only a single CPU anywhere
20 #define __raw_spin_is_locked(x) ((x)->lock != 0)
21 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
22 #define __raw_spin_unlock_wait(x) \
23 do { cpu_relax(); } while (__raw_spin_is_locked(x))
26 * Simple spin lock operations. There are two variants, one clears IRQ's
27 * on the local processor, one does not.
29 * We make no fairness assumptions. They have a cost.
31 static inline void __raw_spin_lock(raw_spinlock_t
*lock
)
33 __asm__
__volatile__ (
44 static inline void __raw_spin_unlock(raw_spinlock_t
*lock
)
46 //assert_spin_locked(lock);
51 #define __raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
54 * Read-write spinlocks, allowing multiple readers but only one writer.
56 * NOTE! it is quite common to have readers in interrupts but no interrupt
57 * writers. For those circumstances we can "mix" irq-safe locks - any writer
58 * needs to get a irq-safe write-lock, but readers can get non-irqsafe
62 static inline void __raw_read_lock(raw_rwlock_t
*rw
)
64 __raw_spin_lock(&rw
->lock
);
66 atomic_inc(&rw
->counter
);
68 __raw_spin_unlock(&rw
->lock
);
71 static inline void __raw_read_unlock(raw_rwlock_t
*rw
)
73 __raw_spin_lock(&rw
->lock
);
75 atomic_dec(&rw
->counter
);
77 __raw_spin_unlock(&rw
->lock
);
80 static inline void __raw_write_lock(raw_rwlock_t
*rw
)
82 __raw_spin_lock(&rw
->lock
);
83 atomic_set(&rw
->counter
, -1);
86 static inline void __raw_write_unlock(raw_rwlock_t
*rw
)
88 atomic_set(&rw
->counter
, 0);
89 __raw_spin_unlock(&rw
->lock
);
92 static inline int __raw_write_can_lock(raw_rwlock_t
*rw
)
94 return (atomic_read(&rw
->counter
) == RW_LOCK_BIAS
);
97 static inline int __raw_read_trylock(raw_rwlock_t
*lock
)
99 atomic_t
*count
= (atomic_t
*)lock
;
100 if (atomic_dec_return(count
) >= 0)
106 static inline int __raw_write_trylock(raw_rwlock_t
*rw
)
108 if (atomic_sub_and_test(RW_LOCK_BIAS
, &rw
->counter
))
111 atomic_add(RW_LOCK_BIAS
, &rw
->counter
);
116 #define _raw_spin_relax(lock) cpu_relax()
117 #define _raw_read_relax(lock) cpu_relax()
118 #define _raw_write_relax(lock) cpu_relax()
120 #endif /* __ASM_SH_SPINLOCK_H */