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authorWill Deacon <will.deacon@arm.com>2019-02-22 13:37:21 +0000
committerWill Deacon <will.deacon@arm.com>2019-04-08 12:00:21 +0100
commite9e8543fecd2e1ca53616ba82fbd55a25cd2ab8a (patch)
treea6139b9501c2b950c997f83273fcb5936c77dd2b /arch/sh
parent0f43ca692dcb55108ea9a59c11a1a0e359dba367 (diff)
downloadlinux-e9e8543fecd2e1ca53616ba82fbd55a25cd2ab8a.tar.bz2
sh/mmiowb: Add unconditional mmiowb() to arch_spin_unlock()
The mmiowb() macro is horribly difficult to use and drivers will continue to work most of the time if they omit a call when it is required. Rather than rely on driver authors getting this right, push mmiowb() into arch_spin_unlock() for sh. If this is deemed to be a performance issue, a subsequent optimisation could make use of ARCH_HAS_MMIOWB to elide the barrier in cases where no I/O writes were performed inside the critical section. Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/include/asm/Kbuild1
-rw-r--r--arch/sh/include/asm/io.h3
-rw-r--r--arch/sh/include/asm/mmiowb.h12
-rw-r--r--arch/sh/include/asm/spinlock-llsc.h2
4 files changed, 14 insertions, 4 deletions
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index 162c9054561f..7bf2cb680d32 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -14,7 +14,6 @@ generic-y += local.h
generic-y += local64.h
generic-y += mcs_spinlock.h
generic-y += mm-arch-hooks.h
-generic-y += mmiowb.h
generic-y += parport.h
generic-y += percpu.h
generic-y += preempt.h
diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h
index 4f7f235f15f8..c28e37a344ad 100644
--- a/arch/sh/include/asm/io.h
+++ b/arch/sh/include/asm/io.h
@@ -229,9 +229,6 @@ __BUILD_IOPORT_STRING(q, u64)
#define IO_SPACE_LIMIT 0xffffffff
-/* synco on SH-4A, otherwise a nop */
-#define mmiowb() wmb()
-
/* We really want to try and get these to memcpy etc */
void memcpy_fromio(void *, const volatile void __iomem *, unsigned long);
void memcpy_toio(volatile void __iomem *, const void *, unsigned long);
diff --git a/arch/sh/include/asm/mmiowb.h b/arch/sh/include/asm/mmiowb.h
new file mode 100644
index 000000000000..535d59735f1d
--- /dev/null
+++ b/arch/sh/include/asm/mmiowb.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_SH_MMIOWB_H
+#define __ASM_SH_MMIOWB_H
+
+#include <asm/barrier.h>
+
+/* synco on SH-4A, otherwise a nop */
+#define mmiowb() wmb()
+
+#include <asm-generic/mmiowb.h>
+
+#endif /* __ASM_SH_MMIOWB_H */
diff --git a/arch/sh/include/asm/spinlock-llsc.h b/arch/sh/include/asm/spinlock-llsc.h
index 786ee0fde3b0..7fd929cd2e7a 100644
--- a/arch/sh/include/asm/spinlock-llsc.h
+++ b/arch/sh/include/asm/spinlock-llsc.h
@@ -47,6 +47,8 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned long tmp;
+ /* This could be optimised with ARCH_HAS_MMIOWB */
+ mmiowb();
__asm__ __volatile__ (
"mov #1, %0 ! arch_spin_unlock \n\t"
"mov.l %0, @%1 \n\t"