1/*
  2 * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
  3 */
  4#ifndef _ASM_POWERPC_MUTEX_H
  5#define _ASM_POWERPC_MUTEX_H
  6
  7static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
  8{
  9	int t;
 10
 11	__asm__ __volatile__ (
 12"1:	lwarx	%0,0,%1		# mutex trylock\n\
 13	cmpw	0,%0,%2\n\
 14	bne-	2f\n"
 15	PPC405_ERR77(0,%1)
 16"	stwcx.	%3,0,%1\n\
 17	bne-	1b"
 18	PPC_ACQUIRE_BARRIER
 19	"\n\
 202:"
 21	: "=&r" (t)
 22	: "r" (&v->counter), "r" (old), "r" (new)
 23	: "cc", "memory");
 24
 25	return t;
 26}
 27
 28static inline int __mutex_dec_return_lock(atomic_t *v)
 29{
 30	int t;
 31
 32	__asm__ __volatile__(
 33"1:	lwarx	%0,0,%1		# mutex lock\n\
 34	addic	%0,%0,-1\n"
 35	PPC405_ERR77(0,%1)
 36"	stwcx.	%0,0,%1\n\
 37	bne-	1b"
 38	PPC_ACQUIRE_BARRIER
 39	: "=&r" (t)
 40	: "r" (&v->counter)
 41	: "cc", "memory");
 42
 43	return t;
 44}
 45
 46static inline int __mutex_inc_return_unlock(atomic_t *v)
 47{
 48	int t;
 49
 50	__asm__ __volatile__(
 51	PPC_RELEASE_BARRIER
 52"1:	lwarx	%0,0,%1		# mutex unlock\n\
 53	addic	%0,%0,1\n"
 54	PPC405_ERR77(0,%1)
 55"	stwcx.	%0,0,%1 \n\
 56	bne-	1b"
 57	: "=&r" (t)
 58	: "r" (&v->counter)
 59	: "cc", "memory");
 60
 61	return t;
 62}
 63
 64/**
 65 *  __mutex_fastpath_lock - try to take the lock by moving the count
 66 *                          from 1 to a 0 value
 67 *  @count: pointer of type atomic_t
 68 *  @fail_fn: function to call if the original value was not 1
 69 *
 70 * Change the count from 1 to a value lower than 1, and call <fail_fn> if
 71 * it wasn't 1 originally. This function MUST leave the value lower than
 72 * 1 even when the "1" assertion wasn't true.
 73 */
 74static inline void
 75__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
 76{
 77	if (unlikely(__mutex_dec_return_lock(count) < 0))
 78		fail_fn(count);
 79}
 80
 81/**
 82 *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
 83 *                                 from 1 to a 0 value
 84 *  @count: pointer of type atomic_t
 85 *
 86 * Change the count from 1 to a value lower than 1. This function returns 0
 87 * if the fastpath succeeds, or -1 otherwise.
 88 */
 89static inline int
 90__mutex_fastpath_lock_retval(atomic_t *count)
 91{
 92	if (unlikely(__mutex_dec_return_lock(count) < 0))
 93		return -1;
 94	return 0;
 95}
 96
 97/**
 98 *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
 99 *  @count: pointer of type atomic_t
100 *  @fail_fn: function to call if the original value was not 0
101 *
102 * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.
103 * In the failure case, this function is allowed to either set the value to
104 * 1, or to set it to a value lower than 1.
105 */
106static inline void
107__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
108{
109	if (unlikely(__mutex_inc_return_unlock(count) <= 0))
110		fail_fn(count);
111}
112
113#define __mutex_slowpath_needs_to_unlock()		1
114
115/**
116 * __mutex_fastpath_trylock - try to acquire the mutex, without waiting
117 *
118 *  @count: pointer of type atomic_t
119 *  @fail_fn: fallback function
120 *
121 * Change the count from 1 to 0, and return 1 (success), or if the count
122 * was not 1, then return 0 (failure).
123 */
124static inline int
125__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
126{
127	if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
128		return 1;
129	return 0;
130}
131
132#endif