1 files changed, 200 insertions, 0 deletions

diff --git a/arch/tile/include/asm/spinlock_32.h b/arch/tile/include/asm/spinlock_32.h
new file mode 100644
index 000000000000..f3a8473c68da
--- /dev/null
+++ b/arch/tile/include/asm/spinlock_32.h
@@ -0,0 +1,200 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ *
+ * 32-bit SMP spinlocks.
+ */
+
+#ifndef _ASM_TILE_SPINLOCK_32_H
+#define _ASM_TILE_SPINLOCK_32_H
+
+#include <asm/atomic.h>
+#include <asm/page.h>
+#include <asm/system.h>
+#include <linux/compiler.h>
+
+/*
+ * We only use even ticket numbers so the '1' inserted by a tns is
+ * an unambiguous "ticket is busy" flag.
+ */
+#define TICKET_QUANTUM 2
+
+
+/*
+ * SMP ticket spinlocks, allowing only a single CPU anywhere
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
+static inline int arch_spin_is_locked(arch_spinlock_t *lock)
+{
+        /*
+         * Note that even if a new ticket is in the process of being
+         * acquired, so lock->next_ticket is 1, it's still reasonable
+         * to claim the lock is held, since it will be momentarily
+         * if not already.  There's no need to wait for a "valid"
+         * lock->next_ticket to become available.
+         */
+        return lock->next_ticket != lock->current_ticket;
+}
+
+void arch_spin_lock(arch_spinlock_t *lock);
+
+/* We cannot take an interrupt after getting a ticket, so don't enable them. */
+#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
+
+int arch_spin_trylock(arch_spinlock_t *lock);
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+        /* For efficiency, overlap fetching the old ticket with the wmb(). */
+        int old_ticket = lock->current_ticket;
+        wmb();  /* guarantee anything modified under the lock is visible */
+        lock->current_ticket = old_ticket + TICKET_QUANTUM;
+}
+
+void arch_spin_unlock_wait(arch_spinlock_t *lock);
+
+/*
+ * Read-write spinlocks, allowing multiple readers
+ * but only one writer.
+ *
+ * We use a "tns/store-back" technique on a single word to manage
+ * the lock state, looping around to retry if the tns returns 1.
+ */
+
+/* Internal layout of the word; do not use. */
+#define _WR_NEXT_SHIFT  8
+#define _WR_CURR_SHIFT  16
+#define _WR_WIDTH       8
+#define _RD_COUNT_SHIFT 24
+#define _RD_COUNT_WIDTH 8
+
+/* Internal functions; do not use. */
+void arch_read_lock_slow(arch_rwlock_t *, u32);
+int arch_read_trylock_slow(arch_rwlock_t *);
+void arch_read_unlock_slow(arch_rwlock_t *);
+void arch_write_lock_slow(arch_rwlock_t *, u32);
+void arch_write_unlock_slow(arch_rwlock_t *, u32);
+
+/**
+ * arch_read_can_lock() - would read_trylock() succeed?
+ */
+static inline int arch_read_can_lock(arch_rwlock_t *rwlock)
+{
+        return (rwlock->lock << _RD_COUNT_WIDTH) == 0;
+}
+
+/**
+ * arch_write_can_lock() - would write_trylock() succeed?
+ */
+static inline int arch_write_can_lock(arch_rwlock_t *rwlock)
+{
+        return rwlock->lock == 0;
+}
+
+/**
+ * arch_read_lock() - acquire a read lock.
+ */
+static inline void arch_read_lock(arch_rwlock_t *rwlock)
+{
+        u32 val = __insn_tns((int *)&rwlock->lock);
+        if (unlikely(val << _RD_COUNT_WIDTH)) {
+                arch_read_lock_slow(rwlock, val);
+                return;
+        }
+        rwlock->lock = val + (1 << _RD_COUNT_SHIFT);
+}
+
+/**
+ * arch_read_lock() - acquire a write lock.
+ */
+static inline void arch_write_lock(arch_rwlock_t *rwlock)
+{
+        u32 val = __insn_tns((int *)&rwlock->lock);
+        if (unlikely(val != 0)) {
+                arch_write_lock_slow(rwlock, val);
+                return;
+        }
+        rwlock->lock = 1 << _WR_NEXT_SHIFT;
+}
+
+/**
+ * arch_read_trylock() - try to acquire a read lock.
+ */
+static inline int arch_read_trylock(arch_rwlock_t *rwlock)
+{
+        int locked;
+        u32 val = __insn_tns((int *)&rwlock->lock);
+        if (unlikely(val & 1)) {
+                return arch_read_trylock_slow(rwlock);
+        }
+        locked = (val << _RD_COUNT_WIDTH) == 0;
+        rwlock->lock = val + (locked << _RD_COUNT_SHIFT);
+        return locked;
+}
+
+/**
+ * arch_write_trylock() - try to acquire a write lock.
+ */
+static inline int arch_write_trylock(arch_rwlock_t *rwlock)
+{
+        u32 val = __insn_tns((int *)&rwlock->lock);
+
+        /*
+         * If a tns is in progress, or there's a waiting or active locker,
+         * or active readers, we can't take the lock, so give up.
+         */
+        if (unlikely(val != 0)) {
+                if (!(val & 1))
+                        rwlock->lock = val;
+                return 0;
+        }
+
+        /* Set the "next" field to mark it locked. */
+        rwlock->lock = 1 << _WR_NEXT_SHIFT;
+        return 1;
+}
+
+/**
+ * arch_read_unlock() - release a read lock.
+ */
+static inline void arch_read_unlock(arch_rwlock_t *rwlock)
+{
+        u32 val;
+        mb();  /* guarantee anything modified under the lock is visible */
+        val = __insn_tns((int *)&rwlock->lock);
+        if (unlikely(val & 1)) {
+                arch_read_unlock_slow(rwlock);
+                return;
+        }
+        rwlock->lock = val - (1 << _RD_COUNT_SHIFT);
+}
+
+/**
+ * arch_write_unlock() - release a write lock.
+ */
+static inline void arch_write_unlock(arch_rwlock_t *rwlock)
+{
+        u32 val;
+        mb();  /* guarantee anything modified under the lock is visible */
+        val = __insn_tns((int *)&rwlock->lock);
+        if (unlikely(val != (1 << _WR_NEXT_SHIFT))) {
+                arch_write_unlock_slow(rwlock, val);
+                return;
+        }
+        rwlock->lock = 0;
+}
+
+#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
+#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
+
+#endif /* _ASM_TILE_SPINLOCK_32_H */