[PATCH] remove powerpc bitops in favor of existing generic bitops
[linux-2.6.git] / arch / powerpc / lib / locks.c
1 /*
2  * Spin and read/write lock operations.
3  *
4  * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
5  * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
6  * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
7  *   Rework to support virtual processors
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License
11  * as published by the Free Software Foundation; either version
12  * 2 of the License, or (at your option) any later version.
13  */
14
15 #include <linux/config.h>
16 #include <linux/kernel.h>
17 #include <linux/spinlock.h>
18 #include <linux/module.h>
19 #include <linux/stringify.h>
20 #include <linux/smp.h>
21
22 /* waiting for a spinlock... */
23 #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
24 #include <asm/hvcall.h>
25 #include <asm/iseries/hv_call.h>
26 #include <asm/smp.h>
27
28 void __spin_yield(raw_spinlock_t *lock)
29 {
30         unsigned int lock_value, holder_cpu, yield_count;
31
32         lock_value = lock->slock;
33         if (lock_value == 0)
34                 return;
35         holder_cpu = lock_value & 0xffff;
36         BUG_ON(holder_cpu >= NR_CPUS);
37         yield_count = lppaca[holder_cpu].yield_count;
38         if ((yield_count & 1) == 0)
39                 return;         /* virtual cpu is currently running */
40         rmb();
41         if (lock->slock != lock_value)
42                 return;         /* something has changed */
43 #ifdef CONFIG_PPC_ISERIES
44         HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
45                 ((u64)holder_cpu << 32) | yield_count);
46 #else
47         plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
48                            yield_count);
49 #endif
50 }
51
52 /*
53  * Waiting for a read lock or a write lock on a rwlock...
54  * This turns out to be the same for read and write locks, since
55  * we only know the holder if it is write-locked.
56  */
57 void __rw_yield(raw_rwlock_t *rw)
58 {
59         int lock_value;
60         unsigned int holder_cpu, yield_count;
61
62         lock_value = rw->lock;
63         if (lock_value >= 0)
64                 return;         /* no write lock at present */
65         holder_cpu = lock_value & 0xffff;
66         BUG_ON(holder_cpu >= NR_CPUS);
67         yield_count = lppaca[holder_cpu].yield_count;
68         if ((yield_count & 1) == 0)
69                 return;         /* virtual cpu is currently running */
70         rmb();
71         if (rw->lock != lock_value)
72                 return;         /* something has changed */
73 #ifdef CONFIG_PPC_ISERIES
74         HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
75                 ((u64)holder_cpu << 32) | yield_count);
76 #else
77         plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
78                            yield_count);
79 #endif
80 }
81 #endif
82
83 void __raw_spin_unlock_wait(raw_spinlock_t *lock)
84 {
85         while (lock->slock) {
86                 HMT_low();
87                 if (SHARED_PROCESSOR)
88                         __spin_yield(lock);
89         }
90         HMT_medium();
91 }
92
93 EXPORT_SYMBOL(__raw_spin_unlock_wait);