Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 192 insertions, 0 deletions

diff --git a/include/asm-sparc/spinlock_32.h b/include/asm-sparc/spinlock_32.h
new file mode 100644
index 000000000000..de2249b267c6
--- /dev/null
+++ b/include/asm-sparc/spinlock_32.h
@@ -0,0 +1,192 @@
+/* spinlock.h: 32-bit Sparc spinlock support.
+ *
+ * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#ifndef __SPARC_SPINLOCK_H
+#define __SPARC_SPINLOCK_H
+
+#include <linux/threads.h>	/* For NR_CPUS */
+
+#ifndef __ASSEMBLY__
+
+#include <asm/psr.h>
+
+#define __raw_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0)
+
+#define __raw_spin_unlock_wait(lock) \
+	do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
+
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+	__asm__ __volatile__(
+	"\n1:\n\t"
+	"ldstub	[%0], %%g2\n\t"
+	"orcc	%%g2, 0x0, %%g0\n\t"
+	"bne,a	2f\n\t"
+	" ldub	[%0], %%g2\n\t"
+	".subsection	2\n"
+	"2:\n\t"
+	"orcc	%%g2, 0x0, %%g0\n\t"
+	"bne,a	2b\n\t"
+	" ldub	[%0], %%g2\n\t"
+	"b,a	1b\n\t"
+	".previous\n"
+	: /* no outputs */
+	: "r" (lock)
+	: "g2", "memory", "cc");
+}
+
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+	unsigned int result;
+	__asm__ __volatile__("ldstub [%1], %0"
+			     : "=r" (result)
+			     : "r" (lock)
+			     : "memory");
+	return (result == 0);
+}
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+	__asm__ __volatile__("stb %%g0, [%0]" : : "r" (lock) : "memory");
+}
+
+/* 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.
+ *
+ * XXX This might create some problems with my dual spinlock
+ * XXX scheme, deadlocks etc. -DaveM
+ *
+ * Sort of like atomic_t's on Sparc, but even more clever.
+ *
+ *	------------------------------------
+ *	| 24-bit counter           | wlock |  raw_rwlock_t
+ *	------------------------------------
+ *	 31                       8 7     0
+ *
+ * wlock signifies the one writer is in or somebody is updating
+ * counter. For a writer, if he successfully acquires the wlock,
+ * but counter is non-zero, he has to release the lock and wait,
+ * till both counter and wlock are zero.
+ *
+ * Unfortunately this scheme limits us to ~16,000,000 cpus.
+ */
+static inline void __read_lock(raw_rwlock_t *rw)
+{
+	register raw_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_enter\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+}
+
+#define __raw_read_lock(lock) \
+do {	unsigned long flags; \
+	local_irq_save(flags); \
+	__read_lock(lock); \
+	local_irq_restore(flags); \
+} while(0)
+
+static inline void __read_unlock(raw_rwlock_t *rw)
+{
+	register raw_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_exit\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+}
+
+#define __raw_read_unlock(lock) \
+do {	unsigned long flags; \
+	local_irq_save(flags); \
+	__read_unlock(lock); \
+	local_irq_restore(flags); \
+} while(0)
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+	register raw_rwlock_t *lp asm("g1");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_write_enter\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: /* no outputs */
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+	*(volatile __u32 *)&lp->lock = ~0U;
+}
+
+static inline int __raw_write_trylock(raw_rwlock_t *rw)
+{
+	unsigned int val;
+
+	__asm__ __volatile__("ldstub [%1 + 3], %0"
+			     : "=r" (val)
+			     : "r" (&rw->lock)
+			     : "memory");
+
+	if (val == 0) {
+		val = rw->lock & ~0xff;
+		if (val)
+			((volatile u8*)&rw->lock)[3] = 0;
+		else
+			*(volatile u32*)&rw->lock = ~0U;
+	}
+
+	return (val == 0);
+}
+
+static inline int __read_trylock(raw_rwlock_t *rw)
+{
+	register raw_rwlock_t *lp asm("g1");
+	register int res asm("o0");
+	lp = rw;
+	__asm__ __volatile__(
+	"mov	%%o7, %%g4\n\t"
+	"call	___rw_read_try\n\t"
+	" ldstub	[%%g1 + 3], %%g2\n"
+	: "=r" (res)
+	: "r" (lp)
+	: "g2", "g4", "memory", "cc");
+	return res;
+}
+
+#define __raw_read_trylock(lock) \
+({	unsigned long flags; \
+	int res; \
+	local_irq_save(flags); \
+	res = __read_trylock(lock); \
+	local_irq_restore(flags); \
+	res; \
+})
+
+#define __raw_write_unlock(rw)	do { (rw)->lock = 0; } while(0)
+
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+
+#define _raw_spin_relax(lock)	cpu_relax()
+#define _raw_read_relax(lock)	cpu_relax()
+#define _raw_write_relax(lock)	cpu_relax()
+
+#define __raw_read_can_lock(rw) (!((rw)->lock & 0xff))
+#define __raw_write_can_lock(rw) (!(rw)->lock)
+
+#endif /* !(__ASSEMBLY__) */
+
+#endif /* __SPARC_SPINLOCK_H */