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author | Michael Trimarchi <trimarchimichael@yahoo.it> | 2008-11-25 21:37:14 +0900 |
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committer | Paul Mundt <lethal@linux-sh.org> | 2008-12-22 18:42:55 +0900 |
commit | 0c9122323acb0c3410dfbd219cb47f4c2e9305e3 (patch) | |
tree | c5ea7c01289bf07e4ad6b5cdd4e830c9122d8e95 /arch | |
parent | 5c72f303a2b7862dbba79f4176ddc922a440b567 (diff) | |
download | op-kernel-dev-0c9122323acb0c3410dfbd219cb47f4c2e9305e3.zip op-kernel-dev-0c9122323acb0c3410dfbd219cb47f4c2e9305e3.tar.gz |
sh: Add SH-4A optimized fastpath mutex implementation.
Add fast mutex path implementation for the SH4A architecture
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/sh/include/asm/mutex-llsc.h | 107 | ||||
-rw-r--r-- | arch/sh/include/asm/mutex.h | 5 |
2 files changed, 111 insertions, 1 deletions
diff --git a/arch/sh/include/asm/mutex-llsc.h b/arch/sh/include/asm/mutex-llsc.h new file mode 100644 index 0000000..7c75af5 --- /dev/null +++ b/arch/sh/include/asm/mutex-llsc.h @@ -0,0 +1,107 @@ +/* + * 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 __res; + + __asm__ __volatile__ ( + "movli.l @%1, %0 \n" + "dt %0 \n" + "movco.l %0, @%1 \n" + : "=&z" (__res) + : "r" (&(count)->counter) + : "t"); + + if (unlikely(__res != 0)) + fail_fn(count); +} + +static inline int +__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) +{ + int __res; + + __asm__ __volatile__ ( + "movli.l @%1, %0 \n" + "dt %0 \n" + "movco.l %0, @%1 \n" + : "=&z" (__res) + : "r" (&(count)->counter) + : "t"); + + if (unlikely(__res != 0)) + __res = fail_fn(count); + + return __res; +} + +static inline void +__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) +{ + int __res; + + __asm__ __volatile__ ( + "1: movli.l @%1, %0 \n\t" + "add #1, %0 \n\t" + "movco.l %0, @%1 \n\t" + "bf 1b\n\t" + : "=&z" (__res) + : "r" (&(count)->counter) + : "t"); + + if (unlikely(__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 */ diff --git a/arch/sh/include/asm/mutex.h b/arch/sh/include/asm/mutex.h index 458c1f7..d8e3771 100644 --- a/arch/sh/include/asm/mutex.h +++ b/arch/sh/include/asm/mutex.h @@ -5,5 +5,8 @@ * implementation in place, or pick the atomic_xchg() based generic * implementation. (see asm-generic/mutex-xchg.h for details) */ - +#if defined(CONFIG_CPU_SH4A) +#include <asm/mutex-llsc.h> +#else #include <asm-generic/mutex-dec.h> +#endif |