diff options
| author | Will Deacon <will.deacon@arm.com> | 2019-02-22 13:37:21 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2019-04-08 12:00:21 +0100 |
| commit | e9e8543fecd2e1ca53616ba82fbd55a25cd2ab8a (patch) | |
| tree | a6139b9501c2b950c997f83273fcb5936c77dd2b /arch/sh | |
| parent | 0f43ca692dcb55108ea9a59c11a1a0e359dba367 (diff) | |
| download | linux-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/Kbuild | 1 | ||||
| -rw-r--r-- | arch/sh/include/asm/io.h | 3 | ||||
| -rw-r--r-- | arch/sh/include/asm/mmiowb.h | 12 | ||||
| -rw-r--r-- | arch/sh/include/asm/spinlock-llsc.h | 2 |
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" |