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/kernel.h> 16#include <linux/spinlock.h> 17#include <linux/module.h> 18#include <linux/stringify.h> 19#include <linux/smp.h> 20 21/* waiting for a spinlock... */ 22#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) 23#include <asm/hvcall.h> 24#include <asm/iseries/hv_call.h> 25#include <asm/smp.h> 26#include <asm/firmware.h> 27 28void __spin_yield(arch_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 if (firmware_has_feature(FW_FEATURE_ISERIES)) 44 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, 45 ((u64)holder_cpu << 32) | yield_count); 46#ifdef CONFIG_PPC_SPLPAR 47 else 48 plpar_hcall_norets(H_CONFER, 49 get_hard_smp_processor_id(holder_cpu), 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 */ 58void __rw_yield(arch_rwlock_t *rw) 59{ 60 int lock_value; 61 unsigned int holder_cpu, yield_count; 62 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); 68 yield_count = lppaca[holder_cpu].yield_count; 69 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 */ 74 if (firmware_has_feature(FW_FEATURE_ISERIES)) 75 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, 76 ((u64)holder_cpu << 32) | yield_count); 77#ifdef CONFIG_PPC_SPLPAR 78 else 79 plpar_hcall_norets(H_CONFER, 80 get_hard_smp_processor_id(holder_cpu), yield_count); 81#endif 82} 83#endif 84 85void arch_spin_unlock_wait(arch_spinlock_t *lock) 86{ 87 while (lock->slock) { 88 HMT_low(); 89 if (SHARED_PROCESSOR) 90 __spin_yield(lock); 91 } 92 HMT_medium(); 93} 94 95EXPORT_SYMBOL(arch_spin_unlock_wait); 96