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Date: Sat, 4 Feb 2017 00:48:32 +0900
From: Stafford Horne <shorne@...il.com>
To: Jonas Bonn <jonas@...thpole.se>,
Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Cc: linux@...ck-us.net, openrisc@...ts.librecores.org,
linux-kernel@...r.kernel.org, Stafford Horne <shorne@...il.com>
Subject: [PATCH v2 08/23] openrisc: add cmpxchg and xchg implementations
From: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Optimized version that make use of the l.lwa and l.swa atomic instruction
pair.
Most openrisc cores provide these instructions now, if not available
emulation is provided.
Signed-off-by: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
[shorne@...il.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by
Alan Cox https://lkml.org/lkml/2014/7/23/666]
[shorne@...il.com: fixed unused calculated value compiler warning in
define cmpxchg]
Signed-off-by: Stafford Horne <shorne@...il.com>
---
arch/openrisc/include/asm/Kbuild | 2 -
arch/openrisc/include/asm/cmpxchg.h | 82 +++++++++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+), 2 deletions(-)
create mode 100644 arch/openrisc/include/asm/cmpxchg.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index 6dd177d..15e6ed5 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -10,8 +10,6 @@ generic-y += bugs.h
generic-y += cacheflush.h
generic-y += checksum.h
generic-y += clkdev.h
-generic-y += cmpxchg-local.h
-generic-y += cmpxchg.h
generic-y += cputime.h
generic-y += current.h
generic-y += device.h
diff --git a/arch/openrisc/include/asm/cmpxchg.h b/arch/openrisc/include/asm/cmpxchg.h
new file mode 100644
index 0000000..6d73c7b
--- /dev/null
+++ b/arch/openrisc/include/asm/cmpxchg.h
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#ifndef __ASM_OPENRISC_CMPXCHG_H
+#define __ASM_OPENRISC_CMPXCHG_H
+
+#include <linux/types.h>
+
+/*
+ * This function doesn't exist, so you'll get a linker error
+ * if something tries to do an invalid cmpxchg().
+ */
+extern void __cmpxchg_called_with_bad_pointer(void);
+
+#define __HAVE_ARCH_CMPXCHG 1
+
+static inline unsigned long
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
+{
+ if (size != 4) {
+ __cmpxchg_called_with_bad_pointer();
+ return old;
+ }
+
+ __asm__ __volatile__(
+ "1: l.lwa %0, 0(%1) \n"
+ " l.sfeq %0, %2 \n"
+ " l.bnf 1f \n"
+ " l.nop \n"
+ " l.swa 0(%1), %3 \n"
+ " l.bnf 1b \n"
+ "1: l.nop \n"
+ : "=&r"(old)
+ : "r"(ptr), "r"(old), "r"(new)
+ : "cc", "memory");
+
+ return old;
+}
+
+#define cmpxchg(ptr, o, n) \
+ ({ \
+ (__typeof__(*(ptr))) __cmpxchg((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
+ })
+
+/*
+ * This function doesn't exist, so you'll get a linker error if
+ * something tries to do an invalidly-sized xchg().
+ */
+extern void __xchg_called_with_bad_pointer(void);
+
+static inline unsigned long __xchg(unsigned long val, volatile void *ptr,
+ int size)
+{
+ if (size != 4) {
+ __xchg_called_with_bad_pointer();
+ return val;
+ }
+
+ __asm__ __volatile__(
+ "1: l.lwa %0, 0(%1) \n"
+ " l.swa 0(%1), %2 \n"
+ " l.bnf 1b \n"
+ " l.nop \n"
+ : "=&r"(val)
+ : "r"(ptr), "r"(val)
+ : "cc", "memory");
+
+ return val;
+}
+
+#define xchg(ptr, with) \
+ ((typeof(*(ptr)))__xchg((unsigned long)(with), (ptr), sizeof(*(ptr))))
+
+#endif /* __ASM_OPENRISC_CMPXCHG_H */
--
2.9.3
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