/*
* ARMv6 Spin-locking.
*
- * We (exclusively) read the old value, and decrement it. If it
- * hits zero, we may have won the lock, so we try (exclusively)
- * storing it.
+ * We exclusively read the old value. If it is zero, we may have
+ * won the lock, so we try exclusively storing it. A memory barrier
+ * is required after we get a lock, and before we release it, because
+ * V6 CPUs are assumed to have weakly ordered memory.
*
* Unlocked value: 0
* Locked value: 1
*/
-typedef struct {
- volatile unsigned int lock;
-#ifdef CONFIG_PREEMPT
- unsigned int break_lock;
-#endif
-} spinlock_t;
-#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
+#define __raw_spin_is_locked(x) ((x)->lock != 0)
+#define __raw_spin_unlock_wait(lock) \
+ do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
-#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while (0)
-#define spin_is_locked(x) ((x)->lock != 0)
-#define spin_unlock_wait(x) do { barrier(); } while (spin_is_locked(x))
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
-static inline void _raw_spin_lock(spinlock_t *lock)
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
unsigned long tmp;
__asm__ __volatile__(
"1: ldrex %0, [%1]\n"
" teq %0, #0\n"
+#ifdef CONFIG_CPU_32v6K
+" wfene\n"
+#endif
" strexeq %0, %2, [%1]\n"
" teqeq %0, #0\n"
" bne 1b"
: "=&r" (tmp)
: "r" (&lock->lock), "r" (1)
- : "cc", "memory");
+ : "cc");
+
+ smp_mb();
}
-static inline int _raw_spin_trylock(spinlock_t *lock)
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
{
unsigned long tmp;
" strexeq %0, %2, [%1]"
: "=&r" (tmp)
: "r" (&lock->lock), "r" (1)
- : "cc", "memory");
-
- return tmp == 0;
+ : "cc");
+
+ if (tmp == 0) {
+ smp_mb();
+ return 1;
+ } else {
+ return 0;
+ }
}
-static inline void _raw_spin_unlock(spinlock_t *lock)
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
+ smp_mb();
+
__asm__ __volatile__(
-" str %1, [%0]"
+" str %1, [%0]\n"
+#ifdef CONFIG_CPU_32v6K
+" mcr p15, 0, %1, c7, c10, 4\n" /* DSB */
+" sev"
+#endif
:
: "r" (&lock->lock), "r" (0)
- : "cc", "memory");
+ : "cc");
}
/*
* RWLOCKS
- */
-typedef struct {
- volatile unsigned int lock;
-#ifdef CONFIG_PREEMPT
- unsigned int break_lock;
-#endif
-} rwlock_t;
-
-#define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
-#define rwlock_init(x) do { *(x) + RW_LOCK_UNLOCKED; } while (0)
-
-/*
+ *
+ *
* Write locks are easy - we just set bit 31. When unlocking, we can
* just write zero since the lock is exclusively held.
*/
-static inline void _raw_write_lock(rwlock_t *rw)
+#define rwlock_is_locked(x) (*((volatile unsigned int *)(x)) != 0)
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
{
unsigned long tmp;
__asm__ __volatile__(
"1: ldrex %0, [%1]\n"
" teq %0, #0\n"
+#ifdef CONFIG_CPU_32v6K
+" wfene\n"
+#endif
" strexeq %0, %2, [%1]\n"
" teq %0, #0\n"
" bne 1b"
: "=&r" (tmp)
: "r" (&rw->lock), "r" (0x80000000)
- : "cc", "memory");
+ : "cc");
+
+ smp_mb();
}
-static inline void _raw_write_unlock(rwlock_t *rw)
+static inline int __raw_write_trylock(raw_rwlock_t *rw)
{
+ unsigned long tmp;
+
__asm__ __volatile__(
- "str %1, [%0]"
+"1: ldrex %0, [%1]\n"
+" teq %0, #0\n"
+" strexeq %0, %2, [%1]"
+ : "=&r" (tmp)
+ : "r" (&rw->lock), "r" (0x80000000)
+ : "cc");
+
+ if (tmp == 0) {
+ smp_mb();
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
+{
+ smp_mb();
+
+ __asm__ __volatile__(
+ "str %1, [%0]\n"
+#ifdef CONFIG_CPU_32v6K
+" mcr p15, 0, %1, c7, c10, 4\n" /* DSB */
+" sev\n"
+#endif
:
: "r" (&rw->lock), "r" (0)
- : "cc", "memory");
+ : "cc");
}
+/* write_can_lock - would write_trylock() succeed? */
+#define __raw_write_can_lock(x) ((x)->lock == 0x80000000)
+
/*
* Read locks are a bit more hairy:
* - Exclusively load the lock value.
* currently active. However, we know we won't have any write
* locks.
*/
-static inline void _raw_read_lock(rwlock_t *rw)
+static inline void __raw_read_lock(raw_rwlock_t *rw)
{
unsigned long tmp, tmp2;
"1: ldrex %0, [%2]\n"
" adds %0, %0, #1\n"
" strexpl %1, %0, [%2]\n"
+#ifdef CONFIG_CPU_32v6K
+" wfemi\n"
+#endif
" rsbpls %0, %1, #0\n"
" bmi 1b"
: "=&r" (tmp), "=&r" (tmp2)
: "r" (&rw->lock)
- : "cc", "memory");
+ : "cc");
+
+ smp_mb();
}
-static inline void _raw_read_unlock(rwlock_t *rw)
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
+ unsigned long tmp, tmp2;
+
+ smp_mb();
+
__asm__ __volatile__(
"1: ldrex %0, [%2]\n"
" sub %0, %0, #1\n"
" strex %1, %0, [%2]\n"
" teq %1, #0\n"
" bne 1b"
+#ifdef CONFIG_CPU_32v6K
+"\n cmp %0, #0\n"
+" mcreq p15, 0, %0, c7, c10, 4\n"
+" seveq"
+#endif
: "=&r" (tmp), "=&r" (tmp2)
: "r" (&rw->lock)
- : "cc", "memory");
+ : "cc");
}
-#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
+#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
-static inline int _raw_write_trylock(rwlock_t *rw)
-{
- unsigned long tmp;
-
- __asm__ __volatile__(
-"1: ldrex %0, [%1]\n"
-" teq %0, #0\n"
-" strexeq %0, %2, [%1]"
- : "=&r" (tmp)
- : "r" (&rw->lock), "r" (0x80000000)
- : "cc", "memory");
-
- return tmp == 0;
-}
+/* read_can_lock - would read_trylock() succeed? */
+#define __raw_read_can_lock(x) ((x)->lock < 0x80000000)
#endif /* __ASM_SPINLOCK_H */
git://git.onelab.eu / linux-2.6.git / blobdiff