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 * @fail_fn: function to call if the original value was not 1 86 * 87 * Change the count from 1 to a value lower than 1, and call <fail_fn> if 88 * it wasn't 1 originally. This function returns 0 if the fastpath succeeds, 89 * or anything the slow path function returns. 90 */ 91static inline int 92__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) 93{ 94 if (unlikely(__mutex_dec_return_lock(count) < 0)) 95 return fail_fn(count); 96 return 0; 97} 98 99/** 100 * __mutex_fastpath_unlock - try to promote the count from 0 to 1 101 * @count: pointer of type atomic_t 102 * @fail_fn: function to call if the original value was not 0 103 * 104 * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>. 105 * In the failure case, this function is allowed to either set the value to 106 * 1, or to set it to a value lower than 1. 107 */ 108static inline void 109__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) 110{ 111 if (unlikely(__mutex_inc_return_unlock(count) <= 0)) 112 fail_fn(count); 113} 114 115#define __mutex_slowpath_needs_to_unlock() 1 116 117/** 118 * __mutex_fastpath_trylock - try to acquire the mutex, without waiting 119 * 120 * @count: pointer of type atomic_t 121 * @fail_fn: fallback function 122 * 123 * Change the count from 1 to 0, and return 1 (success), or if the count 124 * was not 1, then return 0 (failure). 125 */ 126static inline int 127__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) 128{ 129 if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1)) 130 return 1; 131 return 0; 132} 133 134#endif 135