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f5e706ad SR |
1 | /* spinlock.h: 32-bit Sparc spinlock support. |
2 | * | |
3 | * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu) | |
4 | */ | |
5 | ||
6 | #ifndef __SPARC_SPINLOCK_H | |
7 | #define __SPARC_SPINLOCK_H | |
8 | ||
f5e706ad SR |
9 | #ifndef __ASSEMBLY__ |
10 | ||
11 | #include <asm/psr.h> | |
12 | ||
13 | #define __raw_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0) | |
14 | ||
15 | #define __raw_spin_unlock_wait(lock) \ | |
16 | do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0) | |
17 | ||
18 | static inline void __raw_spin_lock(raw_spinlock_t *lock) | |
19 | { | |
20 | __asm__ __volatile__( | |
21 | "\n1:\n\t" | |
22 | "ldstub [%0], %%g2\n\t" | |
23 | "orcc %%g2, 0x0, %%g0\n\t" | |
24 | "bne,a 2f\n\t" | |
25 | " ldub [%0], %%g2\n\t" | |
26 | ".subsection 2\n" | |
27 | "2:\n\t" | |
28 | "orcc %%g2, 0x0, %%g0\n\t" | |
29 | "bne,a 2b\n\t" | |
30 | " ldub [%0], %%g2\n\t" | |
31 | "b,a 1b\n\t" | |
32 | ".previous\n" | |
33 | : /* no outputs */ | |
34 | : "r" (lock) | |
35 | : "g2", "memory", "cc"); | |
36 | } | |
37 | ||
38 | static inline int __raw_spin_trylock(raw_spinlock_t *lock) | |
39 | { | |
40 | unsigned int result; | |
41 | __asm__ __volatile__("ldstub [%1], %0" | |
42 | : "=r" (result) | |
43 | : "r" (lock) | |
44 | : "memory"); | |
45 | return (result == 0); | |
46 | } | |
47 | ||
48 | static inline void __raw_spin_unlock(raw_spinlock_t *lock) | |
49 | { | |
50 | __asm__ __volatile__("stb %%g0, [%0]" : : "r" (lock) : "memory"); | |
51 | } | |
52 | ||
53 | /* Read-write spinlocks, allowing multiple readers | |
54 | * but only one writer. | |
55 | * | |
56 | * NOTE! it is quite common to have readers in interrupts | |
57 | * but no interrupt writers. For those circumstances we | |
58 | * can "mix" irq-safe locks - any writer needs to get a | |
59 | * irq-safe write-lock, but readers can get non-irqsafe | |
60 | * read-locks. | |
61 | * | |
62 | * XXX This might create some problems with my dual spinlock | |
63 | * XXX scheme, deadlocks etc. -DaveM | |
64 | * | |
65 | * Sort of like atomic_t's on Sparc, but even more clever. | |
66 | * | |
67 | * ------------------------------------ | |
68 | * | 24-bit counter | wlock | raw_rwlock_t | |
69 | * ------------------------------------ | |
70 | * 31 8 7 0 | |
71 | * | |
72 | * wlock signifies the one writer is in or somebody is updating | |
73 | * counter. For a writer, if he successfully acquires the wlock, | |
74 | * but counter is non-zero, he has to release the lock and wait, | |
75 | * till both counter and wlock are zero. | |
76 | * | |
77 | * Unfortunately this scheme limits us to ~16,000,000 cpus. | |
78 | */ | |
79 | static inline void __read_lock(raw_rwlock_t *rw) | |
80 | { | |
81 | register raw_rwlock_t *lp asm("g1"); | |
82 | lp = rw; | |
83 | __asm__ __volatile__( | |
84 | "mov %%o7, %%g4\n\t" | |
85 | "call ___rw_read_enter\n\t" | |
86 | " ldstub [%%g1 + 3], %%g2\n" | |
87 | : /* no outputs */ | |
88 | : "r" (lp) | |
89 | : "g2", "g4", "memory", "cc"); | |
90 | } | |
91 | ||
92 | #define __raw_read_lock(lock) \ | |
93 | do { unsigned long flags; \ | |
94 | local_irq_save(flags); \ | |
95 | __read_lock(lock); \ | |
96 | local_irq_restore(flags); \ | |
97 | } while(0) | |
98 | ||
99 | static inline void __read_unlock(raw_rwlock_t *rw) | |
100 | { | |
101 | register raw_rwlock_t *lp asm("g1"); | |
102 | lp = rw; | |
103 | __asm__ __volatile__( | |
104 | "mov %%o7, %%g4\n\t" | |
105 | "call ___rw_read_exit\n\t" | |
106 | " ldstub [%%g1 + 3], %%g2\n" | |
107 | : /* no outputs */ | |
108 | : "r" (lp) | |
109 | : "g2", "g4", "memory", "cc"); | |
110 | } | |
111 | ||
112 | #define __raw_read_unlock(lock) \ | |
113 | do { unsigned long flags; \ | |
114 | local_irq_save(flags); \ | |
115 | __read_unlock(lock); \ | |
116 | local_irq_restore(flags); \ | |
117 | } while(0) | |
118 | ||
119 | static inline void __raw_write_lock(raw_rwlock_t *rw) | |
120 | { | |
121 | register raw_rwlock_t *lp asm("g1"); | |
122 | lp = rw; | |
123 | __asm__ __volatile__( | |
124 | "mov %%o7, %%g4\n\t" | |
125 | "call ___rw_write_enter\n\t" | |
126 | " ldstub [%%g1 + 3], %%g2\n" | |
127 | : /* no outputs */ | |
128 | : "r" (lp) | |
129 | : "g2", "g4", "memory", "cc"); | |
130 | *(volatile __u32 *)&lp->lock = ~0U; | |
131 | } | |
132 | ||
133 | static inline int __raw_write_trylock(raw_rwlock_t *rw) | |
134 | { | |
135 | unsigned int val; | |
136 | ||
137 | __asm__ __volatile__("ldstub [%1 + 3], %0" | |
138 | : "=r" (val) | |
139 | : "r" (&rw->lock) | |
140 | : "memory"); | |
141 | ||
142 | if (val == 0) { | |
143 | val = rw->lock & ~0xff; | |
144 | if (val) | |
145 | ((volatile u8*)&rw->lock)[3] = 0; | |
146 | else | |
147 | *(volatile u32*)&rw->lock = ~0U; | |
148 | } | |
149 | ||
150 | return (val == 0); | |
151 | } | |
152 | ||
153 | static inline int __read_trylock(raw_rwlock_t *rw) | |
154 | { | |
155 | register raw_rwlock_t *lp asm("g1"); | |
156 | register int res asm("o0"); | |
157 | lp = rw; | |
158 | __asm__ __volatile__( | |
159 | "mov %%o7, %%g4\n\t" | |
160 | "call ___rw_read_try\n\t" | |
161 | " ldstub [%%g1 + 3], %%g2\n" | |
162 | : "=r" (res) | |
163 | : "r" (lp) | |
164 | : "g2", "g4", "memory", "cc"); | |
165 | return res; | |
166 | } | |
167 | ||
168 | #define __raw_read_trylock(lock) \ | |
169 | ({ unsigned long flags; \ | |
170 | int res; \ | |
171 | local_irq_save(flags); \ | |
172 | res = __read_trylock(lock); \ | |
173 | local_irq_restore(flags); \ | |
174 | res; \ | |
175 | }) | |
176 | ||
177 | #define __raw_write_unlock(rw) do { (rw)->lock = 0; } while(0) | |
178 | ||
179 | #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock) | |
f5f7eac4 RH |
180 | #define __raw_read_lock_flags(rw, flags) __raw_read_lock(rw) |
181 | #define __raw_write_lock_flags(rw, flags) __raw_write_lock(rw) | |
f5e706ad SR |
182 | |
183 | #define _raw_spin_relax(lock) cpu_relax() | |
184 | #define _raw_read_relax(lock) cpu_relax() | |
185 | #define _raw_write_relax(lock) cpu_relax() | |
186 | ||
187 | #define __raw_read_can_lock(rw) (!((rw)->lock & 0xff)) | |
188 | #define __raw_write_can_lock(rw) (!(rw)->lock) | |
189 | ||
190 | #endif /* !(__ASSEMBLY__) */ | |
191 | ||
192 | #endif /* __SPARC_SPINLOCK_H */ |