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
21extern int spin_retry;
22
23bool 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
36void arch_spin_relax(arch_spinlock_t *lock);
37#define arch_spin_relax	arch_spin_relax
38
39void arch_spin_lock_wait(arch_spinlock_t *);
40int arch_spin_trylock_retry(arch_spinlock_t *);
41void arch_spin_lock_setup(int cpu);
42
43static inline u32 arch_spin_lockval(int cpu)
44{
45	return cpu + 1;
46}
47
48static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
49{
50	return lock.lock == 0;
51}
52
53static inline int arch_spin_is_locked(arch_spinlock_t *lp)
54{
55	return READ_ONCE(lp->lock) != 0;
56}
57
58static 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
64static 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
70static inline int arch_spin_trylock(arch_spinlock_t *lp)
71{
72	if (!arch_spin_trylock_once(lp))
73		return arch_spin_trylock_retry(lp);
74	return 1;
75}
76
77static inline void arch_spin_unlock(arch_spinlock_t *lp)
78{
79	typecheck(int, lp->lock);
80	kcsan_release();
81	asm_inline volatile(
82		ALTERNATIVE("nop", ".insn rre,0xb2fa0000,7,0", 49) /* NIAI 7 */
83		"	sth	%1,%0\n"
84		: "=R" (((unsigned short *) &lp->lock)[1])
85		: "d" (0) : "cc", "memory");
86}
87
88/*
89 * Read-write spinlocks, allowing multiple readers
90 * but only one writer.
91 *
92 * NOTE! it is quite common to have readers in interrupts
93 * but no interrupt writers. For those circumstances we
94 * can "mix" irq-safe locks - any writer needs to get a
95 * irq-safe write-lock, but readers can get non-irqsafe
96 * read-locks.
97 */
98
99#define arch_read_relax(rw) barrier()
100#define arch_write_relax(rw) barrier()
101
102void arch_read_lock_wait(arch_rwlock_t *lp);
103void arch_write_lock_wait(arch_rwlock_t *lp);
104
105static inline void arch_read_lock(arch_rwlock_t *rw)
106{
107	int old;
108
109	old = __atomic_add(1, &rw->cnts);
110	if (old & 0xffff0000)
111		arch_read_lock_wait(rw);
112}
113
114static inline void arch_read_unlock(arch_rwlock_t *rw)
115{
116	__atomic_add_const_barrier(-1, &rw->cnts);
117}
118
119static inline void arch_write_lock(arch_rwlock_t *rw)
120{
121	if (!__atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000))
122		arch_write_lock_wait(rw);
123}
124
125static inline void arch_write_unlock(arch_rwlock_t *rw)
126{
127	__atomic_add_barrier(-0x30000, &rw->cnts);
128}
129
130
131static inline int arch_read_trylock(arch_rwlock_t *rw)
132{
133	int old;
134
135	old = READ_ONCE(rw->cnts);
136	return (!(old & 0xffff0000) &&
137		__atomic_cmpxchg_bool(&rw->cnts, old, old + 1));
138}
139
140static inline int arch_write_trylock(arch_rwlock_t *rw)
141{
142	int old;
143
144	old = READ_ONCE(rw->cnts);
145	return !old && __atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000);
146}
147
148#endif /* __ASM_SPINLOCK_H */
149