1 #ifndef __CB_BDK_SPINLOCK_H__
2 #define __CB_BDK_SPINLOCK_H__
3 /***********************license start***********************************
4 * Copyright (c) 2003-2017 Cavium Inc. ([email protected]). All rights
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16 * copyright notice, this list of conditions and the following
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21 * its contributors may be used to endorse or promote products
22 * derived from this software without specific prior written
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27 * associated regulations, and may be subject to export or import
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29 *
30 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, THE SOFTWARE IS PROVIDED "AS IS"
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40 ***********************license end**************************************/
41
42 /**
43 * @file
44 *
45 * Implementation of spinlocks.
46 *
47 * <hr>$Revision: 49448 $<hr>
48 *
49 * @addtogroup hal
50 * @{
51 */
52
53 /**
54 * Spinlocks
55 */
56 typedef union
57 {
58 uint64_t combined;
59 struct
60 {
61 #if __BYTE_ORDER == __BIG_ENDIAN
62 uint32_t ticket;
63 uint32_t serving;
64 #else
65 uint32_t serving;
66 uint32_t ticket;
67 #endif
68 } s;
69 } bdk_spinlock_t;
70
71 /**
72 * Initialize a spinlock
73 *
74 * @param lock Lock to initialize
75 */
bdk_spinlock_init(bdk_spinlock_t * lock)76 static inline void bdk_spinlock_init(bdk_spinlock_t *lock)
77 {
78 asm volatile ("str xzr, [%[b]]"
79 : "+m" (lock->combined)
80 : [b] "r" (&lock->combined)
81 : "memory");
82 }
83
84 /**
85 * Releases lock
86 *
87 * @param lock pointer to lock structure
88 */
89 static inline void bdk_spinlock_unlock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
bdk_spinlock_unlock(bdk_spinlock_t * lock)90 static inline void bdk_spinlock_unlock(bdk_spinlock_t *lock)
91 {
92 /* Implies a release */
93 asm volatile ("stlr %w[v], [%[b]]"
94 : "+m" (lock->s.serving)
95 : [v] "r" (lock->s.serving + 1), [b] "r" (&lock->s.serving)
96 : "memory");
97 }
98
99 /**
100 * Gets lock, spins until lock is taken
101 *
102 * @param lock pointer to lock structure
103 */
104 static inline void bdk_spinlock_lock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
bdk_spinlock_lock(bdk_spinlock_t * lock)105 static inline void bdk_spinlock_lock(bdk_spinlock_t *lock)
106 {
107 uint64_t combined;
108 uint32_t ticket;
109 uint32_t serving;
110
111 asm volatile (
112 "mov %x[serving], 1<<32 \n"
113 "ldadda %x[serving], %x[combined], [%[ptr]] \n"
114 "and %x[serving], %x[combined], 0xffffffff \n"
115 "lsr %x[ticket], %x[combined], 32 \n"
116 "cmp %x[ticket], %x[serving] \n"
117 "b.eq 1f \n"
118 "sevl \n"
119 "2: wfe \n"
120 "ldxr %w[serving], [%[ptr2]] \n"
121 "cmp %x[ticket], %x[serving] \n"
122 "b.ne 2b \n"
123 "1: \n"
124 : [serving] "=&r" (serving), [ticket] "=&r" (ticket), [combined] "=&r" (combined), "+m" (lock->combined)
125 : [ptr] "r" (&lock->combined), [ptr2] "r" (&lock->s.serving)
126 : "memory"
127 );
128 }
129
130 /**
131 * Trys to get the lock, failing if we can't get it immediately
132 *
133 * @param lock pointer to lock structure
134 */
135 static inline int bdk_spinlock_trylock(bdk_spinlock_t *lock) __attribute__ ((always_inline));
bdk_spinlock_trylock(bdk_spinlock_t * lock)136 static inline int bdk_spinlock_trylock(bdk_spinlock_t *lock)
137 {
138 uint64_t combined = *(volatile uint64_t *)&lock->combined;
139 uint32_t ticket = combined >> 32;
140 uint32_t serving = (uint32_t)combined;
141 if (ticket != serving)
142 return -1;
143 uint64_t new_combined = combined + (1ull << 32);
144 bool success = bdk_atomic_compare_and_store64(&lock->combined, combined, new_combined);
145 return success ? 0 : -1;
146 }
147
148 /** @} */
149 #endif /* !__CB_BDK_SPINLOCK_H__ */
150