From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
---
 include/asm-sh/spinlock.h | 124 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 include/asm-sh/spinlock.h

(limited to 'include/asm-sh/spinlock.h')

diff --git a/include/asm-sh/spinlock.h b/include/asm-sh/spinlock.h
new file mode 100644
index 00000000000..e770b55649e
--- /dev/null
+++ b/include/asm-sh/spinlock.h
@@ -0,0 +1,124 @@
+/*
+ * include/asm-sh/spinlock.h
+ *
+ * Copyright (C) 2002, 2003 Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#ifndef __ASM_SH_SPINLOCK_H
+#define __ASM_SH_SPINLOCK_H
+
+#include <asm/atomic.h>
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ */
+typedef struct {
+	volatile unsigned long lock;
+#ifdef CONFIG_PREEMPT
+	unsigned int break_lock;
+#endif
+} spinlock_t;
+
+#define SPIN_LOCK_UNLOCKED	(spinlock_t) { 0 }
+
+#define spin_lock_init(x)	do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
+
+#define spin_is_locked(x)	((x)->lock != 0)
+#define spin_unlock_wait(x)	do { barrier(); } while (spin_is_locked(x))
+#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+
+/*
+ * Simple spin lock operations.  There are two variants, one clears IRQ's
+ * on the local processor, one does not.
+ *
+ * We make no fairness assumptions.  They have a cost.
+ */
+static inline void _raw_spin_lock(spinlock_t *lock)
+{
+	__asm__ __volatile__ (
+		"1:\n\t"
+		"tas.b @%0\n\t"
+		"bf/s 1b\n\t"
+		"nop\n\t"
+		: "=r" (lock->lock)
+		: "r" (&lock->lock)
+		: "t", "memory"
+	);
+}
+
+static inline void _raw_spin_unlock(spinlock_t *lock)
+{
+	assert_spin_locked(lock);
+
+	lock->lock = 0;
+}
+
+#define _raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
+
+/*
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ *
+ * NOTE! it is quite common to have readers in interrupts but no interrupt
+ * writers. For those circumstances we can "mix" irq-safe locks - any writer
+ * needs to get a irq-safe write-lock, but readers can get non-irqsafe
+ * read-locks.
+ */
+typedef struct {
+	spinlock_t lock;
+	atomic_t counter;
+#ifdef CONFIG_PREEMPT
+	unsigned int break_lock;
+#endif
+} rwlock_t;
+
+#define RW_LOCK_BIAS		0x01000000
+#define RW_LOCK_UNLOCKED	(rwlock_t) { { 0 }, { RW_LOCK_BIAS } }
+#define rwlock_init(x)		do { *(x) = RW_LOCK_UNLOCKED; } while (0)
+
+static inline void _raw_read_lock(rwlock_t *rw)
+{
+	_raw_spin_lock(&rw->lock);
+
+	atomic_inc(&rw->counter);
+
+	_raw_spin_unlock(&rw->lock);
+}
+
+static inline void _raw_read_unlock(rwlock_t *rw)
+{
+	_raw_spin_lock(&rw->lock);
+
+	atomic_dec(&rw->counter);
+
+	_raw_spin_unlock(&rw->lock);
+}
+
+static inline void _raw_write_lock(rwlock_t *rw)
+{
+	_raw_spin_lock(&rw->lock);
+	atomic_set(&rw->counter, -1);
+}
+
+static inline void _raw_write_unlock(rwlock_t *rw)
+{
+	atomic_set(&rw->counter, 0);
+	_raw_spin_unlock(&rw->lock);
+}
+
+#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
+
+static inline int _raw_write_trylock(rwlock_t *rw)
+{
+	if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
+		return 1;
+	
+	atomic_add(RW_LOCK_BIAS, &rw->counter);
+
+	return 0;
+}
+
+#endif /* __ASM_SH_SPINLOCK_H */
+
-- 
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