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linux/include/asm-m32r/spinlock.h
Hirokazu Takata 85f651794c [PATCH] m32r: revise __raw_read_trylock() 
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-27 08:26:15 -07:00

320 lines
7.5 KiB
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#ifndef _ASM_M32R_SPINLOCK_H
#define _ASM_M32R_SPINLOCK_H
/*
* linux/include/asm-m32r/spinlock.h
*
* M32R version:
* Copyright (C) 2001, 2002 Hitoshi Yamamoto
* Copyright (C) 2004 Hirokazu Takata <takata at linux-m32r.org>
*/
#include <linux/compiler.h>
#include <asm/atomic.h>
#include <asm/page.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*
* (the type definitions are in asm/spinlock_types.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 __raw_spin_is_locked(x) (*(volatile int *)(&(x)->slock) <= 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(x) \
do { cpu_relax(); } while (__raw_spin_is_locked(x))
/**
* __raw_spin_trylock - Try spin lock and return a result
* @lock: Pointer to the lock variable
*
* __raw_spin_trylock() tries to get the lock and returns a result.
* On the m32r, the result value is 1 (= Success) or 0 (= Failure).
*/
static inline int __raw_spin_trylock(raw_spinlock_t *lock)
{
int oldval;
unsigned long tmp1, tmp2;
/*
* lock->slock : =1 : unlock
* : <=0 : lock
* {
* oldval = lock->slock; <--+ need atomic operation
* lock->slock = 0; <--+
* }
*/
__asm__ __volatile__ (
"# __raw_spin_trylock \n\t"
"ldi %1, #0; \n\t"
"mvfc %2, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r6", "%3")
"lock %0, @%3; \n\t"
"unlock %1, @%3; \n\t"
"mvtc %2, psw; \n\t"
: "=&r" (oldval), "=&r" (tmp1), "=&r" (tmp2)
: "r" (&lock->slock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r6"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
return (oldval > 0);
}
static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
unsigned long tmp0, tmp1;
/*
* lock->slock : =1 : unlock
* : <=0 : lock
*
* for ( ; ; ) {
* lock->slock -= 1; <-- need atomic operation
* if (lock->slock == 0) break;
* for ( ; lock->slock <= 0 ; );
* }
*/
__asm__ __volatile__ (
"# __raw_spin_lock \n\t"
".fillinsn \n"
"1: \n\t"
"mvfc %1, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r6", "%2")
"lock %0, @%2; \n\t"
"addi %0, #-1; \n\t"
"unlock %0, @%2; \n\t"
"mvtc %1, psw; \n\t"
"bltz %0, 2f; \n\t"
LOCK_SECTION_START(".balign 4 \n\t")
".fillinsn \n"
"2: \n\t"
"ld %0, @%2; \n\t"
"bgtz %0, 1b; \n\t"
"bra 2b; \n\t"
LOCK_SECTION_END
: "=&r" (tmp0), "=&r" (tmp1)
: "r" (&lock->slock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r6"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
}
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
mb();
lock->slock = 1;
}
/*
* 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.
*
* On x86, we implement read-write locks as a 32-bit counter
* with the high bit (sign) being the "contended" bit.
*
* The inline assembly is non-obvious. Think about it.
*
* Changed to use the same technique as rw semaphores. See
* semaphore.h for details. -ben
*/
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define __raw_read_can_lock(x) ((int)(x)->lock > 0)
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
unsigned long tmp0, tmp1;
/*
* rw->lock : >0 : unlock
* : <=0 : lock
*
* for ( ; ; ) {
* rw->lock -= 1; <-- need atomic operation
* if (rw->lock >= 0) break;
* rw->lock += 1; <-- need atomic operation
* for ( ; rw->lock <= 0 ; );
* }
*/
__asm__ __volatile__ (
"# read_lock \n\t"
".fillinsn \n"
"1: \n\t"
"mvfc %1, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r6", "%2")
"lock %0, @%2; \n\t"
"addi %0, #-1; \n\t"
"unlock %0, @%2; \n\t"
"mvtc %1, psw; \n\t"
"bltz %0, 2f; \n\t"
LOCK_SECTION_START(".balign 4 \n\t")
".fillinsn \n"
"2: \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r6", "%2")
"lock %0, @%2; \n\t"
"addi %0, #1; \n\t"
"unlock %0, @%2; \n\t"
"mvtc %1, psw; \n\t"
".fillinsn \n"
"3: \n\t"
"ld %0, @%2; \n\t"
"bgtz %0, 1b; \n\t"
"bra 3b; \n\t"
LOCK_SECTION_END
: "=&r" (tmp0), "=&r" (tmp1)
: "r" (&rw->lock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r6"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
unsigned long tmp0, tmp1, tmp2;
/*
* rw->lock : =RW_LOCK_BIAS_STR : unlock
* : !=RW_LOCK_BIAS_STR : lock
*
* for ( ; ; ) {
* rw->lock -= RW_LOCK_BIAS_STR; <-- need atomic operation
* if (rw->lock == 0) break;
* rw->lock += RW_LOCK_BIAS_STR; <-- need atomic operation
* for ( ; rw->lock != RW_LOCK_BIAS_STR ; ) ;
* }
*/
__asm__ __volatile__ (
"# write_lock \n\t"
"seth %1, #high(" RW_LOCK_BIAS_STR "); \n\t"
"or3 %1, %1, #low(" RW_LOCK_BIAS_STR "); \n\t"
".fillinsn \n"
"1: \n\t"
"mvfc %2, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r7", "%3")
"lock %0, @%3; \n\t"
"sub %0, %1; \n\t"
"unlock %0, @%3; \n\t"
"mvtc %2, psw; \n\t"
"bnez %0, 2f; \n\t"
LOCK_SECTION_START(".balign 4 \n\t")
".fillinsn \n"
"2: \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r7", "%3")
"lock %0, @%3; \n\t"
"add %0, %1; \n\t"
"unlock %0, @%3; \n\t"
"mvtc %2, psw; \n\t"
".fillinsn \n"
"3: \n\t"
"ld %0, @%3; \n\t"
"beq %0, %1, 1b; \n\t"
"bra 3b; \n\t"
LOCK_SECTION_END
: "=&r" (tmp0), "=&r" (tmp1), "=&r" (tmp2)
: "r" (&rw->lock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r7"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
}
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
unsigned long tmp0, tmp1;
__asm__ __volatile__ (
"# read_unlock \n\t"
"mvfc %1, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r6", "%2")
"lock %0, @%2; \n\t"
"addi %0, #1; \n\t"
"unlock %0, @%2; \n\t"
"mvtc %1, psw; \n\t"
: "=&r" (tmp0), "=&r" (tmp1)
: "r" (&rw->lock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r6"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
unsigned long tmp0, tmp1, tmp2;
__asm__ __volatile__ (
"# write_unlock \n\t"
"seth %1, #high(" RW_LOCK_BIAS_STR "); \n\t"
"or3 %1, %1, #low(" RW_LOCK_BIAS_STR "); \n\t"
"mvfc %2, psw; \n\t"
"clrpsw #0x40 -> nop; \n\t"
DCACHE_CLEAR("%0", "r7", "%3")
"lock %0, @%3; \n\t"
"add %0, %1; \n\t"
"unlock %0, @%3; \n\t"
"mvtc %2, psw; \n\t"
: "=&r" (tmp0), "=&r" (tmp1), "=&r" (tmp2)
: "r" (&rw->lock)
: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
, "r7"
#endif /* CONFIG_CHIP_M32700_TS1 */
);
}
static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t*)lock;
if (atomic_dec_return(count) >= 0)
return 1;
atomic_inc(count);
return 0;
}
static inline int __raw_write_trylock(raw_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;
}
#endif /* _ASM_M32R_SPINLOCK_H */
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