arch/s390/include/asm/spinlock.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *  S390 version
   4  *    Copyright IBM Corp. 1999
   5  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   6  *
   7  *  Derived from "include/asm-i386/spinlock.h"
   8  */
   9
  10 #ifndef __ASM_SPINLOCK_H
  11 #define __ASM_SPINLOCK_H
  12
  13 #include <linux/smp.h>
  14 #include <asm/atomic_ops.h>
  15 #include <asm/barrier.h>
  16 #include <asm/processor.h>
  17 #include <asm/alternative.h>
  18
  19 #define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)
  20
  21 extern int spin_retry;
  22
  23 bool arch_vcpu_is_preempted(int cpu);
  24
  25 #define vcpu_is_preempted arch_vcpu_is_preempted
  26
  27 /*
  28  * Simple spin lock operations.  There are two variants, one clears IRQ's
  29  * on the local processor, one does not.
  30  *
  31  * We make no fairness assumptions. They have a cost.
  32  *
  33  * (the type definitions are in asm/spinlock_types.h)
  34  */
  35
  36 void arch_spin_relax(arch_spinlock_t *lock);
  37 #define arch_spin_relax arch_spin_relax
  38
  39 void arch_spin_lock_wait(arch_spinlock_t *);
  40 int arch_spin_trylock_retry(arch_spinlock_t *);
  41 void arch_spin_lock_setup(int cpu);
  42
  43 static inline u32 arch_spin_lockval(int cpu)
  44 {
  45         return cpu + 1;
  46 }
  47
  48 static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
  49 {
  50         return lock.lock == 0;
  51 }
  52
  53 static inline int arch_spin_is_locked(arch_spinlock_t *lp)
  54 {
  55         return READ_ONCE(lp->lock) != 0;
  56 }
  57
  58 static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
  59 {
  60         barrier();
  61         return likely(__atomic_cmpxchg_bool(&lp->lock, 0, SPINLOCK_LOCKVAL));
  62 }
  63
  64 static inline void arch_spin_lock(arch_spinlock_t *lp)
  65 {
  66         if (!arch_spin_trylock_once(lp))
  67                 arch_spin_lock_wait(lp);
  68 }
  69
  70 static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
  71                                         unsigned long flags)
  72 {
  73         if (!arch_spin_trylock_once(lp))
  74                 arch_spin_lock_wait(lp);
  75 }
  76 #define arch_spin_lock_flags    arch_spin_lock_flags
  77
  78 static inline int arch_spin_trylock(arch_spinlock_t *lp)
  79 {
  80         if (!arch_spin_trylock_once(lp))
  81                 return arch_spin_trylock_retry(lp);
  82         return 1;
  83 }
  84
  85 static inline void arch_spin_unlock(arch_spinlock_t *lp)
  86 {
  87         typecheck(int, lp->lock);
  88         asm volatile(
  89                 ALTERNATIVE("", ".long 0xb2fa0070", 49) /* NIAI 7 */
  90                 "       sth     %1,%0\n"
  91                 : "=Q" (((unsigned short *) &lp->lock)[1])
  92                 : "d" (0) : "cc", "memory");
  93 }
  94
  95 /*
  96  * Read-write spinlocks, allowing multiple readers
  97  * but only one writer.
  98  *
  99  * NOTE! it is quite common to have readers in interrupts
 100  * but no interrupt writers. For those circumstances we
 101  * can "mix" irq-safe locks - any writer needs to get a
 102  * irq-safe write-lock, but readers can get non-irqsafe
 103  * read-locks.
 104  */
 105
 106 #define arch_read_relax(rw) barrier()
 107 #define arch_write_relax(rw) barrier()
 108
 109 void arch_read_lock_wait(arch_rwlock_t *lp);
 110 void arch_write_lock_wait(arch_rwlock_t *lp);
 111
 112 static inline void arch_read_lock(arch_rwlock_t *rw)
 113 {
 114         int old;
 115
 116         old = __atomic_add(1, &rw->cnts);
 117         if (old & 0xffff0000)
 118                 arch_read_lock_wait(rw);
 119 }
 120
 121 static inline void arch_read_unlock(arch_rwlock_t *rw)
 122 {
 123         __atomic_add_const_barrier(-1, &rw->cnts);
 124 }
 125
 126 static inline void arch_write_lock(arch_rwlock_t *rw)
 127 {
 128         if (!__atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000))
 129                 arch_write_lock_wait(rw);
 130 }
 131
 132 static inline void arch_write_unlock(arch_rwlock_t *rw)
 133 {
 134         __atomic_add_barrier(-0x30000, &rw->cnts);
 135 }
 136
 137
 138 static inline int arch_read_trylock(arch_rwlock_t *rw)
 139 {
 140         int old;
 141
 142         old = READ_ONCE(rw->cnts);
 143         return (!(old & 0xffff0000) &&
 144                 __atomic_cmpxchg_bool(&rw->cnts, old, old + 1));
 145 }
 146
 147 static inline int arch_write_trylock(arch_rwlock_t *rw)
 148 {
 149         int old;
 150
 151         old = READ_ONCE(rw->cnts);
 152         return !old && __atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000);
 153 }
 154
 155 #endif /* __ASM_SPINLOCK_H */