blob: ee395e392115b418e07d1a3fcb4ace04ed09a44d [file] [log] [blame]
Paul Mackerras40ef8cb2005-10-10 22:50:37 +10001/*
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
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100015#include <linux/kernel.h>
16#include <linux/spinlock.h>
17#include <linux/module.h>
18#include <linux/stringify.h>
Paul Mackerras734d6522005-10-31 13:57:01 +110019#include <linux/smp.h>
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100020
21/* waiting for a spinlock... */
22#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
23#include <asm/hvcall.h>
Kelly Daly1da44032005-11-01 16:59:20 +110024#include <asm/iseries/hv_call.h>
Paul Mackerras2249ca92005-11-07 13:18:13 +110025#include <asm/smp.h>
Stephen Rothwell4f896e52006-08-24 13:29:33 +100026#include <asm/firmware.h>
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100027
Thomas Gleixner445c8952009-12-02 19:49:50 +010028void __spin_yield(arch_spinlock_t *lock)
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100029{
30 unsigned int lock_value, holder_cpu, yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100031
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);
David Gibson3356bb9f72006-01-13 10:26:42 +110037 yield_count = lppaca[holder_cpu].yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100038 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 */
Stephen Rothwell4f896e52006-08-24 13:29:33 +100043 if (firmware_has_feature(FW_FEATURE_ISERIES))
44 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
45 ((u64)holder_cpu << 32) | yield_count);
Stephen Rothwell1c56f832007-02-23 14:41:41 +110046#ifdef CONFIG_PPC_SPLPAR
Stephen Rothwell4f896e52006-08-24 13:29:33 +100047 else
48 plpar_hcall_norets(H_CONFER,
49 get_hard_smp_processor_id(holder_cpu), yield_count);
Stephen Rothwell1c56f832007-02-23 14:41:41 +110050#endif
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100051}
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 */
58void __rw_yield(raw_rwlock_t *rw)
59{
60 int lock_value;
61 unsigned int holder_cpu, yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100062
63 lock_value = rw->lock;
64 if (lock_value >= 0)
65 return; /* no write lock at present */
66 holder_cpu = lock_value & 0xffff;
67 BUG_ON(holder_cpu >= NR_CPUS);
David Gibson3356bb9f72006-01-13 10:26:42 +110068 yield_count = lppaca[holder_cpu].yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100069 if ((yield_count & 1) == 0)
70 return; /* virtual cpu is currently running */
71 rmb();
72 if (rw->lock != lock_value)
73 return; /* something has changed */
Stephen Rothwell4f896e52006-08-24 13:29:33 +100074 if (firmware_has_feature(FW_FEATURE_ISERIES))
75 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
76 ((u64)holder_cpu << 32) | yield_count);
Stephen Rothwell1c56f832007-02-23 14:41:41 +110077#ifdef CONFIG_PPC_SPLPAR
Stephen Rothwell4f896e52006-08-24 13:29:33 +100078 else
79 plpar_hcall_norets(H_CONFER,
80 get_hard_smp_processor_id(holder_cpu), yield_count);
Stephen Rothwell1c56f832007-02-23 14:41:41 +110081#endif
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100082}
83#endif
84
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010085void arch_spin_unlock_wait(arch_spinlock_t *lock)
Paul Mackerras40ef8cb2005-10-10 22:50:37 +100086{
87 while (lock->slock) {
88 HMT_low();
89 if (SHARED_PROCESSOR)
90 __spin_yield(lock);
91 }
92 HMT_medium();
93}
94
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010095EXPORT_SYMBOL(arch_spin_unlock_wait);