1 files changed, 132 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/mutex.h b/arch/powerpc/include/asm/mutex.h
new file mode 100644
index 000000000..127ab23e1
--- /dev/null
+++ b/arch/powerpc/include/asm/mutex.h
@@ -0,0 +1,132 @@
+/*
+ * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
+ */
+#ifndef _ASM_POWERPC_MUTEX_H
+#define _ASM_POWERPC_MUTEX_H
+
+static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
+{
+	int t;
+
+	__asm__ __volatile__ (
+"1:	lwarx	%0,0,%1		# mutex trylock\n\
+	cmpw	0,%0,%2\n\
+	bne-	2f\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.	%3,0,%1\n\
+	bne-	1b"
+	PPC_ACQUIRE_BARRIER
+	"\n\
+2:"
+	: "=&r" (t)
+	: "r" (&v->counter), "r" (old), "r" (new)
+	: "cc", "memory");
+
+	return t;
+}
+
+static inline int __mutex_dec_return_lock(atomic_t *v)
+{
+	int t;
+
+	__asm__ __volatile__(
+"1:	lwarx	%0,0,%1		# mutex lock\n\
+	addic	%0,%0,-1\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.	%0,0,%1\n\
+	bne-	1b"
+	PPC_ACQUIRE_BARRIER
+	: "=&r" (t)
+	: "r" (&v->counter)
+	: "cc", "memory");
+
+	return t;
+}
+
+static inline int __mutex_inc_return_unlock(atomic_t *v)
+{
+	int t;
+
+	__asm__ __volatile__(
+	PPC_RELEASE_BARRIER
+"1:	lwarx	%0,0,%1		# mutex unlock\n\
+	addic	%0,%0,1\n"
+	PPC405_ERR77(0,%1)
+"	stwcx.	%0,0,%1 \n\
+	bne-	1b"
+	: "=&r" (t)
+	: "r" (&v->counter)
+	: "cc", "memory");
+
+	return t;
+}
+
+/**
+ *  __mutex_fastpath_lock - try to take the lock by moving the count
+ *                          from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function MUST leave the value lower than
+ * 1 even when the "1" assertion wasn't true.
+ */
+static inline void
+__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
+{
+	if (unlikely(__mutex_dec_return_lock(count) < 0))
+		fail_fn(count);
+}
+
+/**
+ *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
+ *                                 from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
+ */
+static inline int
+__mutex_fastpath_lock_retval(atomic_t *count)
+{
+	if (unlikely(__mutex_dec_return_lock(count) < 0))
+		return -1;
+	return 0;
+}
+
+/**
+ *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
+ *  @count: pointer of type atomic_t
+ *  @fail_fn: function to call if the original value was not 0
+ *
+ * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.
+ * In the failure case, this function is allowed to either set the value to
+ * 1, or to set it to a value lower than 1.
+ */
+static inline void
+__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
+{
+	if (unlikely(__mutex_inc_return_unlock(count) <= 0))
+		fail_fn(count);
+}
+
+#define __mutex_slowpath_needs_to_unlock()		1
+
+/**
+ * __mutex_fastpath_trylock - try to acquire the mutex, without waiting
+ *
+ *  @count: pointer of type atomic_t
+ *  @fail_fn: fallback function
+ *
+ * Change the count from 1 to 0, and return 1 (success), or if the count
+ * was not 1, then return 0 (failure).
+ */
+static inline int
+__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
+{
+	if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
+		return 1;
+	return 0;
+}
+
+#endif