summaryrefslogtreecommitdiffstats
path: root/arch/ia64/include/asm/spinlock.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--arch/ia64/include/asm/spinlock.h265
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 */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 06:16:13 +0000