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