diff options
Diffstat (limited to 'arch/ia64/include/asm/spinlock.h')
-rw-r--r-- | arch/ia64/include/asm/spinlock.h | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h new file mode 100644 index 0000000000..0e5c1ad323 --- /dev/null +++ b/arch/ia64/include/asm/spinlock.h @@ -0,0 +1,265 @@ +/* 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 */ |