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Diffstat (limited to 'arch/mn10300/include/asm/spinlock.h')
| -rw-r--r-- | arch/mn10300/include/asm/spinlock.h | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/mn10300/include/asm/spinlock.h b/arch/mn10300/include/asm/spinlock.h new file mode 100644 index 000000000..1ae580f38 --- /dev/null +++ b/arch/mn10300/include/asm/spinlock.h @@ -0,0 +1,193 @@ +/* MN10300 spinlock support + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#ifndef _ASM_SPINLOCK_H +#define _ASM_SPINLOCK_H + +#include <linux/atomic.h> +#include <asm/rwlock.h> +#include <asm/page.h> + +/* + * Simple spin lock operations. There are two variants, one clears IRQ's + * on the local processor, one does not. + * + * We make no fairness assumptions. They have a cost. + */ + +#define arch_spin_is_locked(x) (*(volatile signed char *)(&(x)->slock) != 0) +#define arch_spin_unlock_wait(x) do { barrier(); } while (arch_spin_is_locked(x)) + +static inline void arch_spin_unlock(arch_spinlock_t *lock) +{ + asm volatile( + " bclr 1,(0,%0) \n" + : + : "a"(&lock->slock) + : "memory", "cc"); +} + +static inline int arch_spin_trylock(arch_spinlock_t *lock) +{ + int ret; + + asm volatile( + " mov 1,%0 \n" + " bset %0,(%1) \n" + " bne 1f \n" + " clr %0 \n" + "1: xor 1,%0 \n" + : "=d"(ret) + : "a"(&lock->slock) + : "memory", "cc"); + + return ret; +} + +static inline void arch_spin_lock(arch_spinlock_t *lock) +{ + asm volatile( + "1: bset 1,(0,%0) \n" + " bne 1b \n" + : + : "a"(&lock->slock) + : "memory", "cc"); +} + +static inline void arch_spin_lock_flags(arch_spinlock_t *lock, + unsigned long flags) +{ + int temp; + + asm volatile( + "1: bset 1,(0,%2) \n" + " beq 3f \n" + " mov %1,epsw \n" + "2: mov (0,%2),%0 \n" + " or %0,%0 \n" + " bne 2b \n" + " mov %3,%0 \n" + " mov %0,epsw \n" + " nop \n" + " nop \n" + " bra 1b\n" + "3: \n" + : "=&d" (temp) + : "d" (flags), "a"(&lock->slock), "i"(EPSW_IE | MN10300_CLI_LEVEL) + : "memory", "cc"); +} + +#ifdef __KERNEL__ + +/* + * Read-write spinlocks, allowing multiple readers + * but only one writer. + * + * NOTE! it is quite common to have readers in interrupts + * but no interrupt writers. For those circumstances we + * can "mix" irq-safe locks - any writer needs to get a + * irq-safe write-lock, but readers can get non-irqsafe + * read-locks. + */ + +/** + * read_can_lock - would read_trylock() succeed? + * @lock: the rwlock in question. + */ +#define arch_read_can_lock(x) ((int)(x)->lock > 0) + +/** + * write_can_lock - would write_trylock() succeed? + * @lock: the rwlock in question. + */ +#define arch_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) + +/* + * On mn10300, we implement read-write locks as a 32-bit counter + * with the high bit (sign) being the "contended" bit. + */ +static inline void arch_read_lock(arch_rwlock_t *rw) +{ +#if 0 //def CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT + __build_read_lock(rw, "__read_lock_failed"); +#else + { + atomic_t *count = (atomic_t *)rw; + while (atomic_dec_return(count) < 0) + atomic_inc(count); + } +#endif +} + +static inline void arch_write_lock(arch_rwlock_t *rw) +{ +#if 0 //def CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT + __build_write_lock(rw, "__write_lock_failed"); +#else + { + atomic_t *count = (atomic_t *)rw; + while (!atomic_sub_and_test(RW_LOCK_BIAS, count)) + atomic_add(RW_LOCK_BIAS, count); + } +#endif +} + +static inline void arch_read_unlock(arch_rwlock_t *rw) +{ +#if 0 //def CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT + __build_read_unlock(rw); +#else + { + atomic_t *count = (atomic_t *)rw; + atomic_inc(count); + } +#endif +} + +static inline void arch_write_unlock(arch_rwlock_t *rw) +{ +#if 0 //def CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT + __build_write_unlock(rw); +#else + { + atomic_t *count = (atomic_t *)rw; + atomic_add(RW_LOCK_BIAS, count); + } +#endif +} + +static inline int arch_read_trylock(arch_rwlock_t *lock) +{ + atomic_t *count = (atomic_t *)lock; + atomic_dec(count); + if (atomic_read(count) >= 0) + return 1; + atomic_inc(count); + return 0; +} + +static inline int arch_write_trylock(arch_rwlock_t *lock) +{ + atomic_t *count = (atomic_t *)lock; + if (atomic_sub_and_test(RW_LOCK_BIAS, count)) + return 1; + atomic_add(RW_LOCK_BIAS, count); + return 0; +} + +#define arch_read_lock_flags(lock, flags) arch_read_lock(lock) +#define arch_write_lock_flags(lock, flags) arch_write_lock(lock) + +#define _raw_spin_relax(lock) cpu_relax() +#define _raw_read_relax(lock) cpu_relax() +#define _raw_write_relax(lock) cpu_relax() + +#endif /* __KERNEL__ */ +#endif /* _ASM_SPINLOCK_H */ |