/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_IA64_SPINLOCK_H
#define _ASM_IA64_SPINLOCK_H
/*
* Copyright (C) 1998-2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
* Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
*
* This file is used for SMP configurations only.
*/
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/atomic.h>
#include <asm/intrinsics.h>
#include <asm/barrier.h>
#include <asm/processor.h>
#define arch_spin_lock_init(x) ((x)->lock = 0)
/*
* Ticket locks are conceptually two parts, one indicating the current head of
* the queue, and the other indicating the current tail. The lock is acquired
* by atomically noting the tail and incrementing it by one (thus adding
* ourself to the queue and noting our position), then waiting until the head
* becomes equal to the initial value of the tail.
* The pad bits in the middle are used to prevent the next_ticket number
* overflowing into the now_serving number.
*
* 31 17 16 15 14 0
* +----------------------------------------------------+
* | now_serving | padding | next_ticket |
* +----------------------------------------------------+
*/
#define TICKET_SHIFT 17
#define TICKET_BITS 15
#define TICKET_MASK ((1 << TICKET_BITS) - 1)
static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
{
int *p = (int *)&lock->lock, ticket, serve;
ticket = ia64_fetchadd(1, p, acq);
if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
return;
ia64_invala();
for (;;) {
asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(p) : "memory");
if (!(((serve >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
return;
cpu_relax();
}
}
static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
{
int tmp = READ_ONCE(lock->lock);
if (!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK))
return ia64_cmpxchg(acq, &lock->lock, tmp, tmp + 1, sizeof (tmp)) == tmp;
return 0;
}
static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
{
unsigned short *p = (unsigned short *)&lock->lock + 1, tmp;
/* This could be optimised with ARCH_HAS_MMIOWB */
mmiowb();
asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p));
WRITE_ONCE(*p, (tmp + 2) & ~1);
}
static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
{
long tmp = READ_ONCE(lock->lock);
return !!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK);
}
static inline int __ticket_spin_is_contended(arch_spinlock_t *lock)
{
long tmp = READ_ONCE(lock->lock);
return ((tmp - (tmp >> TICKET_SHIFT)) & TICKET_MASK) > 1;
}
static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
return !(((lock.lock >> TICKET_SHIFT) ^ lock.lock) & TICKET_MASK);
}
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
return __ticket_spin_is_locked(lock);
}
static inline int arch_spin_is_contended(arch_spinlock_t *lock)
{
return __ticket_spin_is_contended(lock);
}
#define arch_spin_is_contended arch_spin_is_contended
static __always_inline void arch_spin_lock(arch_spinlock_t *lock)
{
__ticket_spin_lock(lock);
}
static __always_inline int arch_spin_trylock(arch_spinlock_t *lock)
{
return __ticket_spin_trylock(lock);
}
static __always_inline void arch_spin_unlock(arch_spinlock_t *lock)
{
__ticket_spin_unlock(lock);
}
#ifdef ASM_SUPPORTED
static __always_inline void
arch_read_lock(arch_rwlock_t *lock)
{
unsigned long flags = 0;
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1,%2\n"
"br.few 3f\n"
"1:\n"
"fetchadd4.rel r2 = [%0], -1;;\n"
"(p6) ssm psr.i\n"
"2:\n"
"hint @pause\n"
"ld4 r2 = [%0];;\n"
"cmp4.lt p7,p0 = r2, r0\n"
"(p7) br.cond.spnt.few 2b\n"
"(p6) rsm psr.i\n"
";;\n"
"3:\n"
"fetchadd4.acq r2 = [%0], 1;;\n"
"cmp4.lt p7,p0 = r2, r0\n"
"(p7) br.cond.spnt.few 1b\n"
: : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
: "p6", "p7", "r2", "memory");
}
#else /* !ASM_SUPPORTED */
#define arch_read_lock(rw) \
do { \
arch_rwlock_t *__read_lock_ptr = (rw); \
\
while (unlikely(ia64_fetchadd(1, (int *) __read_lock_ptr, acq) < 0)) { \
ia64_fetchadd(-1, (int *) __read_lock_ptr, rel); \
while (*(volatile int *)__read_lock_ptr < 0) \
cpu_relax(); \
} \
} while (0)
#endif /* !ASM_SUPPORTED */
#define arch_read_unlock(rw) \
do { \
arch_rwlock_t *__read_lock_ptr = (rw); \
ia64_fetchadd(-1, (int *) __read_lock_ptr, rel); \
} while (0)
#ifdef ASM_SUPPORTED
static __always_inline void
arch_write_lock(arch_rwlock_t *lock)
{
unsigned long flags = 0;
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1, %2\n"
"mov ar.ccv = r0\n"
"dep r29 = -1, r0, 31, 1\n"
"br.few 3f;;\n"
"1:\n"
"(p6) ssm psr.i\n"
"2:\n"
"hint @pause\n"
"ld4 r2 = [%0];;\n"
"cmp4.eq p0,p7 = r0, r2\n"
"(p7) br.cond.spnt.few 2b\n"
"(p6) rsm psr.i\n"
";;\n"
"3:\n"
"cmpxchg4.acq r2 = [%0], r29, ar.ccv;;\n"
"cmp4.eq p0,p7 = r0, r2\n"
"(p7) br.cond.spnt.few 1b;;\n"
: : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
: "ar.ccv", "p6", "p7", "r2", "r29", "memory");
}
#define arch_write_trylock(rw) \
({ \
register long result; \
\
__asm__ __volatile__ ( \
"mov ar.ccv = r0\n" \
"dep r29 = -1, r0, 31, 1;;\n" \
"cmpxchg4.acq %0 = [%1], r29, ar.ccv\n" \
: "=r"(result) : "r"(rw) : "ar.ccv", "r29", "memory"); \
(result == 0); \
})
static inline void arch_write_unlock(arch_rwlock_t *x)
{
u8 *y = (u8 *)x;
barrier();
asm volatile ("st1.rel.nta [%0] = r0\n\t" :: "r"(y+3) : "memory" );
}
#else /* !ASM_SUPPORTED */
#define arch_write_lock(l) \
({ \
__u64 ia64_val, ia64_set_val = ia64_dep_mi(-1, 0, 31, 1); \
__u32 *ia64_write_lock_ptr = (__u32 *) (l); \
do { \
while (*ia64_write_lock_ptr) \
ia64_barrier(); \
ia64_val = ia64_cmpxchg4_acq(ia64_write_lock_ptr, ia64_set_val, 0); \
} while (ia64_val); \
})
#define arch_write_trylock(rw) \
({ \
__u64 ia64_val; \
__u64 ia64_set_val = ia64_dep_mi(-1, 0, 31,1); \
ia64_val = ia64_cmpxchg4_acq((__u32 *)(rw), ia64_set_val, 0); \
(ia64_val == 0); \
})
static inline void arch_write_unlock(arch_rwlock_t *x)
{
barrier();
x->write_lock = 0;
}
#endif /* !ASM_SUPPORTED */
static inline int arch_read_trylock(arch_rwlock_t *x)
{
union {
arch_rwlock_t lock;
__u32 word;
} old, new;
old.lock = new.lock = *x;
old.lock.write_lock = new.lock.write_lock = 0;
++new.lock.read_counter;
return (u32)ia64_cmpxchg4_acq((__u32 *)(x), new.word, old.word) == old.word;
}
#endif /* _ASM_IA64_SPINLOCK_H */