Merge Paulus' tree
[linux-2.6] / 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
27 void __spin_yield(raw_spinlock_t *lock)
28 {
29         unsigned int lock_value, holder_cpu, yield_count;
30         struct paca_struct *holder_paca;
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         holder_paca = &paca[holder_cpu];
38         yield_count = holder_paca->lppaca.yield_count;
39         if ((yield_count & 1) == 0)
40                 return;         /* virtual cpu is currently running */
41         rmb();
42         if (lock->slock != lock_value)
43                 return;         /* something has changed */
44 #ifdef CONFIG_PPC_ISERIES
45         HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
46                 ((u64)holder_cpu << 32) | yield_count);
47 #else
48         plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
49                            yield_count);
50 #endif
51 }
52
53 /*
54  * Waiting for a read lock or a write lock on a rwlock...
55  * This turns out to be the same for read and write locks, since
56  * we only know the holder if it is write-locked.
57  */
58 void __rw_yield(raw_rwlock_t *rw)
59 {
60         int lock_value;
61         unsigned int holder_cpu, yield_count;
62         struct paca_struct *holder_paca;
63
64         lock_value = rw->lock;
65         if (lock_value >= 0)
66                 return;         /* no write lock at present */
67         holder_cpu = lock_value & 0xffff;
68         BUG_ON(holder_cpu >= NR_CPUS);
69         holder_paca = &paca[holder_cpu];
70         yield_count = holder_paca->lppaca.yield_count;
71         if ((yield_count & 1) == 0)
72                 return;         /* virtual cpu is currently running */
73         rmb();
74         if (rw->lock != lock_value)
75                 return;         /* something has changed */
76 #ifdef CONFIG_PPC_ISERIES
77         HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
78                 ((u64)holder_cpu << 32) | yield_count);
79 #else
80         plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
81                            yield_count);
82 #endif
83 }
84 #endif
85
86 void __raw_spin_unlock_wait(raw_spinlock_t *lock)
87 {
88         while (lock->slock) {
89                 HMT_low();
90                 if (SHARED_PROCESSOR)
91                         __spin_yield(lock);
92         }
93         HMT_medium();
94 }
95
96 EXPORT_SYMBOL(__raw_spin_unlock_wait);