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gerrit-public.fairphone.software / kernel / msm-4.9 / 4f896e53eea70013fa48d0d8662680cf8aae8a43 / . / arch / powerpc / lib / locks.c
blob: 80b482ca30dfac7e8098e0d1b8cafd3ecc82656c [file] [log] [blame]
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]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
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]15#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 +1100[diff] [blame]19#include <linux/smp.h>
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]20
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 +1100[diff] [blame]24#include <asm/iseries/hv_call.h>
Paul Mackerras2249ca92005-11-07 13:18:13 +1100[diff] [blame]25#include <asm/smp.h>
Stephen Rothwell4f896e52006-08-24 13:29:33 +1000[diff] [blame^]26#include <asm/firmware.h>
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]27
28void __spin_yield(raw_spinlock_t *lock)
29{
30 unsigned int lock_value, holder_cpu, yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]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);
David Gibson3356bb9f72006-01-13 10:26:42 +1100[diff] [blame]37 yield_count = lppaca[holder_cpu].yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]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 */
Stephen Rothwell4f896e52006-08-24 13:29:33 +1000[diff] [blame^]43 if (firmware_has_feature(FW_FEATURE_ISERIES))
44 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
45 ((u64)holder_cpu << 32) | yield_count);
46 else
47 plpar_hcall_norets(H_CONFER,
48 get_hard_smp_processor_id(holder_cpu), yield_count);
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]49}
50
51/*
52 * Waiting for a read lock or a write lock on a rwlock...
53 * This turns out to be the same for read and write locks, since
54 * we only know the holder if it is write-locked.
55 */
56void __rw_yield(raw_rwlock_t *rw)
57{
58 int lock_value;
59 unsigned int holder_cpu, yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]60
61 lock_value = rw->lock;
62 if (lock_value >= 0)
63 return; /* no write lock at present */
64 holder_cpu = lock_value & 0xffff;
65 BUG_ON(holder_cpu >= NR_CPUS);
David Gibson3356bb9f72006-01-13 10:26:42 +1100[diff] [blame]66 yield_count = lppaca[holder_cpu].yield_count;
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]67 if ((yield_count & 1) == 0)
68 return; /* virtual cpu is currently running */
69 rmb();
70 if (rw->lock != lock_value)
71 return; /* something has changed */
Stephen Rothwell4f896e52006-08-24 13:29:33 +1000[diff] [blame^]72 if (firmware_has_feature(FW_FEATURE_ISERIES))
73 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
74 ((u64)holder_cpu << 32) | yield_count);
75 else
76 plpar_hcall_norets(H_CONFER,
77 get_hard_smp_processor_id(holder_cpu), yield_count);
Paul Mackerras40ef8cb2005-10-10 22:50:37 +1000[diff] [blame]78}
79#endif
80
81void __raw_spin_unlock_wait(raw_spinlock_t *lock)
82{
83 while (lock->slock) {
84 HMT_low();
85 if (SHARED_PROCESSOR)
86 __spin_yield(lock);
87 }
88 HMT_medium();
89}
90
91EXPORT_SYMBOL(__raw_spin_unlock_wait);