Initial import

1 files changed, 223 insertions, 0 deletions

diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
new file mode 100644
index 000000000..a83bbea62
--- /dev/null
+++ b/arch/alpha/include/asm/rwsem.h
@@ -0,0 +1,223 @@
+#ifndef _ALPHA_RWSEM_H
+#define _ALPHA_RWSEM_H
+
+/*
+ * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001.
+ * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
+ */
+
+#ifndef _LINUX_RWSEM_H
+#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
+#endif
+
+#ifdef __KERNEL__
+
+#include <linux/compiler.h>
+
+#define RWSEM_UNLOCKED_VALUE		0x0000000000000000L
+#define RWSEM_ACTIVE_BIAS		0x0000000000000001L
+#define RWSEM_ACTIVE_MASK		0x00000000ffffffffL
+#define RWSEM_WAITING_BIAS		(-0x0000000100000000L)
+#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
+#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
+
+static inline void __down_read(struct rw_semaphore *sem)
+{
+	long oldcount;
+#ifndef	CONFIG_SMP
+	oldcount = sem->count;
+	sem->count += RWSEM_ACTIVE_READ_BIAS;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	addq	%0,%3,%2\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	"	mb\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
+#endif
+	if (unlikely(oldcount < 0))
+		rwsem_down_read_failed(sem);
+}
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_read_trylock(struct rw_semaphore *sem)
+{
+	long old, new, res;
+
+	res = sem->count;
+	do {
+		new = res + RWSEM_ACTIVE_READ_BIAS;
+		if (new <= 0)
+			break;
+		old = res;
+		res = cmpxchg(&sem->count, old, new);
+	} while (res != old);
+	return res >= 0 ? 1 : 0;
+}
+
+static inline void __down_write(struct rw_semaphore *sem)
+{
+	long oldcount;
+#ifndef	CONFIG_SMP
+	oldcount = sem->count;
+	sem->count += RWSEM_ACTIVE_WRITE_BIAS;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	addq	%0,%3,%2\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	"	mb\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
+#endif
+	if (unlikely(oldcount))
+		rwsem_down_write_failed(sem);
+}
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_write_trylock(struct rw_semaphore *sem)
+{
+	long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
+			   RWSEM_ACTIVE_WRITE_BIAS);
+	if (ret == RWSEM_UNLOCKED_VALUE)
+		return 1;
+	return 0;
+}
+
+static inline void __up_read(struct rw_semaphore *sem)
+{
+	long oldcount;
+#ifndef	CONFIG_SMP
+	oldcount = sem->count;
+	sem->count -= RWSEM_ACTIVE_READ_BIAS;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"	mb\n"
+	"1:	ldq_l	%0,%1\n"
+	"	subq	%0,%3,%2\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
+#endif
+	if (unlikely(oldcount < 0))
+		if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0)
+			rwsem_wake(sem);
+}
+
+static inline void __up_write(struct rw_semaphore *sem)
+{
+	long count;
+#ifndef	CONFIG_SMP
+	sem->count -= RWSEM_ACTIVE_WRITE_BIAS;
+	count = sem->count;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"	mb\n"
+	"1:	ldq_l	%0,%1\n"
+	"	subq	%0,%3,%2\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	"	subq	%0,%3,%0\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (count), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
+#endif
+	if (unlikely(count))
+		if ((int)count == 0)
+			rwsem_wake(sem);
+}
+
+/*
+ * downgrade write lock to read lock
+ */
+static inline void __downgrade_write(struct rw_semaphore *sem)
+{
+	long oldcount;
+#ifndef	CONFIG_SMP
+	oldcount = sem->count;
+	sem->count -= RWSEM_WAITING_BIAS;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	addq	%0,%3,%2\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	"	mb\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory");
+#endif
+	if (unlikely(oldcount < 0))
+		rwsem_downgrade_wake(sem);
+}
+
+static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem)
+{
+#ifndef	CONFIG_SMP
+	sem->count += val;
+#else
+	long temp;
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	addq	%0,%2,%0\n"
+	"	stq_c	%0,%1\n"
+	"	beq	%0,2f\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (temp), "=m" (sem->count)
+	:"Ir" (val), "m" (sem->count));
+#endif
+}
+
+static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem)
+{
+#ifndef	CONFIG_SMP
+	sem->count += val;
+	return sem->count;
+#else
+	long ret, temp;
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	addq 	%0,%3,%2\n"
+	"	addq	%0,%3,%0\n"
+	"	stq_c	%2,%1\n"
+	"	beq	%2,2f\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	:"=&r" (ret), "=m" (sem->count), "=&r" (temp)
+	:"Ir" (val), "m" (sem->count));
+
+	return ret;
+#endif
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ALPHA_RWSEM_H */