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>
16 * Your basic SMP spinlocks, allowing only a single CPU anywhere
19 volatile unsigned long lock;
22 #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
24 #define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
26 #define spin_is_locked(x) ((x)->lock != 0)
27 #define spin_unlock_wait(x) do { barrier(); } while (spin_is_locked(x))
30 * Simple spin lock operations. There are two variants, one clears IRQ's
31 * on the local processor, one does not.
33 * We make no fairness assumptions. They have a cost.
35 static inline void _raw_spin_lock(spinlock_t *lock)
37 __asm__ __volatile__ (
48 static inline void _raw_spin_unlock(spinlock_t *lock)
50 #ifdef CONFIG_DEBUG_SPINLOCK
51 BUG_ON(!spin_is_locked(lock));
57 #define _raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
60 * Read-write spinlocks, allowing multiple readers but only one writer.
62 * NOTE! it is quite common to have readers in interrupts but no interrupt
63 * writers. For those circumstances we can "mix" irq-safe locks - any writer
64 * needs to get a irq-safe write-lock, but readers can get non-irqsafe
72 #define RW_LOCK_BIAS 0x01000000
73 #define RW_LOCK_UNLOCKED (rwlock_t) { { 0 }, { RW_LOCK_BIAS } }
74 #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while (0)
75 #define rwlock_is_locked(x) (atomic_read(&(x)->counter) != RW_LOCK_BIAS)
77 static inline void _raw_read_lock(rwlock_t *rw)
79 _raw_spin_lock(&rw->lock);
81 atomic_inc(&rw->counter);
83 _raw_spin_unlock(&rw->lock);
86 static inline void _raw_read_unlock(rwlock_t *rw)
88 _raw_spin_lock(&rw->lock);
90 atomic_dec(&rw->counter);
92 _raw_spin_unlock(&rw->lock);
95 static inline void _raw_write_lock(rwlock_t *rw)
97 _raw_spin_lock(&rw->lock);
98 atomic_set(&rw->counter, -1);
101 static inline void _raw_write_unlock(rwlock_t *rw)
103 atomic_set(&rw->counter, 0);
104 _raw_spin_unlock(&rw->lock);
107 static inline int _raw_write_trylock(rwlock_t *rw)
109 if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
112 atomic_add(RW_LOCK_BIAS, &rw->counter);
117 #endif /* __ASM_SH_SPINLOCK_H */