110 lines
2.6 KiB
C
110 lines
2.6 KiB
C
|
/*
|
||
|
|
* arch/sh/include/asm/mutex-llsc.h
|
||
|
|
*
|
||
|
|
* SH-4A optimized mutex locking primitives
|
||
|
|
*
|
||
|
|
* Please look into asm-generic/mutex-xchg.h for a formal definition.
|
||
|
|
*/
|
||
|
|
#ifndef __ASM_SH_MUTEX_LLSC_H
|
||
|
|
#define __ASM_SH_MUTEX_LLSC_H
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Attempting to lock a mutex on SH4A is done like in ARMv6+ architecure.
|
||
|
|
* with a bastardized atomic decrement (it is not a reliable atomic decrement
|
||
|
|
* but it satisfies the defined semantics for our purpose, while being
|
||
|
|
* smaller and faster than a real atomic decrement or atomic swap.
|
||
|
|
* The idea is to attempt decrementing the lock value only once. If once
|
||
|
|
* decremented it isn't zero, or if its store-back fails due to a dispute
|
||
|
|
* on the exclusive store, we simply bail out immediately through the slow
|
||
|
|
* path where the lock will be reattempted until it succeeds.
|
||
|
|
*/
|
||
|
|
static inline void
|
||
|
|
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
|
||
|
|
{
|
||
|
|
int __done, __res;
|
||
|
|
|
||
|
|
__asm__ __volatile__ (
|
||
|
|
"movli.l @%2, %0 \n"
|
||
|
|
"add #-1, %0 \n"
|
||
|
|
"movco.l %0, @%2 \n"
|
||
|
|
"movt %1 \n"
|
||
|
|
: "=&z" (__res), "=&r" (__done)
|
||
|
|
: "r" (&(count)->counter)
|
||
|
|
: "t");
|
||
|
|
|
||
|
|
if (unlikely(!__done || __res != 0))
|
||
|
|
fail_fn(count);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline int
|
||
|
|
__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
|
||
|
|
{
|
||
|
|
int __done, __res;
|
||
|
|
|
||
|
|
__asm__ __volatile__ (
|
||
|
|
"movli.l @%2, %0 \n"
|
||
|
|
"add #-1, %0 \n"
|
||
|
|
"movco.l %0, @%2 \n"
|
||
|
|
"movt %1 \n"
|
||
|
|
: "=&z" (__res), "=&r" (__done)
|
||
|
|
: "r" (&(count)->counter)
|
||
|
|
: "t");
|
||
|
|
|
||
|
|
if (unlikely(!__done || __res != 0))
|
||
|
|
__res = fail_fn(count);
|
||
|
|
|
||
|
|
return __res;
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline void
|
||
|
|
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
|
||
|
|
{
|
||
|
|
int __done, __res;
|
||
|
|
|
||
|
|
__asm__ __volatile__ (
|
||
|
|
"movli.l @%2, %0 \n\t"
|
||
|
|
"add #1, %0 \n\t"
|
||
|
|
"movco.l %0, @%2 \n\t"
|
||
|
|
"movt %1 \n\t"
|
||
|
|
: "=&z" (__res), "=&r" (__done)
|
||
|
|
: "r" (&(count)->counter)
|
||
|
|
: "t");
|
||
|
|
|
||
|
|
if (unlikely(!__done || __res <= 0))
|
||
|
|
fail_fn(count);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* If the unlock was done on a contended lock, or if the unlock simply fails
|
||
|
|
* then the mutex remains locked.
|
||
|
|
*/
|
||
|
|
#define __mutex_slowpath_needs_to_unlock() 1
|
||
|
|
|
||
|
|
/*
|
||
|
|
* For __mutex_fastpath_trylock we do an atomic decrement and check the
|
||
|
|
* result and put it in the __res variable.
|
||
|
|
*/
|
||
|
|
static inline int
|
||
|
|
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
|
||
|
|
{
|
||
|
|
int __res, __orig;
|
||
|
|
|
||
|
|
__asm__ __volatile__ (
|
||
|
|
"1: movli.l @%2, %0 \n\t"
|
||
|
|
"dt %0 \n\t"
|
||
|
|
"movco.l %0,@%2 \n\t"
|
||
|
|
"bf 1b \n\t"
|
||
|
|
"cmp/eq #0,%0 \n\t"
|
||
|
|
"bt 2f \n\t"
|
||
|
|
"mov #0, %1 \n\t"
|
||
|
|
"bf 3f \n\t"
|
||
|
|
"2: mov #1, %1 \n\t"
|
||
|
|
"3: "
|
||
|
|
: "=&z" (__orig), "=&r" (__res)
|
||
|
|
: "r" (&count->counter)
|
||
|
|
: "t");
|
||
|
|
|
||
|
|
return __res;
|
||
|
|
}
|
||
|
|
#endif /* __ASM_SH_MUTEX_LLSC_H */
|