From 6bb69d6c15cfcf207c38dd3102f150ae81eab8b5 Mon Sep 17 00:00:00 2001
From: Kyle McMartin <kyle@parisc-linux.org>
Date: Tue, 29 May 2007 02:51:13 -0700
Subject: [PATCH] --- yaml --- r: 57079 b: refs/heads/master c:
 6197fe4d720ea3e2ee94cdc7ef32d6c0151199de h: refs/heads/master i:   57077:
 03eb7305b8ceb1e2c5889289c97113de01f789b1   57075:
 8a08463bcdf07e991d01e58280b26a8e467da4c7   57071:
 2a06e24cf6e2a5de0bfa66f1e975207e39f57ce0 v: v3

---
 [refs]                           |  2 +-
 trunk/arch/sparc/lib/atomic32.c  | 15 +++++++++++++
 trunk/include/asm-sparc/atomic.h | 38 ++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 370321113bb6..ab58b3cefaeb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 679292993c77c06f7ade4e317c13256b92c2651b
+refs/heads/master: 6197fe4d720ea3e2ee94cdc7ef32d6c0151199de
diff --git a/trunk/arch/sparc/lib/atomic32.c b/trunk/arch/sparc/lib/atomic32.c
index 559335f4917d..617d29832e19 100644
--- a/trunk/arch/sparc/lib/atomic32.c
+++ b/trunk/arch/sparc/lib/atomic32.c
@@ -2,6 +2,7 @@
  * atomic32.c: 32-bit atomic_t implementation
  *
  * Copyright (C) 2004 Keith M Wesolowski
+ * Copyright (C) 2007 Kyle McMartin
  * 
  * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
  */
@@ -117,3 +118,17 @@ unsigned long ___change_bit(unsigned long *addr, unsigned long mask)
 	return old & mask;
 }
 EXPORT_SYMBOL(___change_bit);
+
+unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
+{
+	unsigned long flags;
+	u32 prev;
+
+	spin_lock_irqsave(ATOMIC_HASH(addr), flags);
+	if ((prev = *ptr) == old)
+		*ptr = new;
+	spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
+
+	return (unsigned long)prev;
+}
+EXPORT_SYMBOL(__cmpxchg_u32);
diff --git a/trunk/include/asm-sparc/atomic.h b/trunk/include/asm-sparc/atomic.h
index 731fa56e0c37..bdca5416d8b0 100644
--- a/trunk/include/asm-sparc/atomic.h
+++ b/trunk/include/asm-sparc/atomic.h
@@ -2,6 +2,7 @@
  *
  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
  * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
+ * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
  *
  * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
  * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
@@ -10,11 +11,48 @@
 #ifndef __ARCH_SPARC_ATOMIC__
 #define __ARCH_SPARC_ATOMIC__
 
+#include <linux/types.h>
 
 typedef struct { volatile int counter; } atomic_t;
 
 #ifdef __KERNEL__
 
+/* Emulate cmpxchg() the same way we emulate atomics,
+ * by hashing the object address and indexing into an array
+ * of spinlocks to get a bit of performance...
+ *
+ * See arch/sparc/lib/atomic32.c for implementation.
+ *
+ * Cribbed from <asm-parisc/atomic.h>
+ */
+#define __HAVE_ARCH_CMPXCHG	1
+
+/* bug catcher for when unsupported size is used - won't link */
+extern void __cmpxchg_called_with_bad_pointer(void);
+/* we only need to support cmpxchg of a u32 on sparc */
+extern unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
+
+/* don't worry...optimizer will get rid of most of this */
+static __inline__ unsigned long
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
+{
+	switch(size) {
+	case 4:
+		return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
+	default:
+		__cmpxchg_called_with_bad_pointer();
+		break;
+	}
+	return old;
+}
+
+#define cmpxchg(ptr,o,n) ({						\
+	__typeof__(*(ptr)) _o_ = (o);					\
+	__typeof__(*(ptr)) _n_ = (n);					\
+	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
+			(unsigned long)_n_, sizeof(*(ptr)));		\
+})
+
 #define ATOMIC_INIT(i)  { (i) }
 
 extern int __atomic_add_return(int, atomic_t *);