From: Dave.Martin@arm.com (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 3/4] ARM: Add const cpu_to_le32 for asm
Date: Wed, 9 Oct 2013 15:29:52 +0100 [thread overview]
Message-ID: <1381328993-12724-4-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1381328993-12724-1-git-send-email-Dave.Martin@arm.com>
On ARM, it's common for big-endian systems to use little-endian
byte order for devices.
This patch adds a __asm_cpu_to_le32() helper, similar to
cpu_to_le32(). This is intended for preparing 32-bit constants to
be stored to a device, or compared with data loaded from a device.
Rather than add umpteen variants up front, extra variants can be
added when needed. Accessing devices directly from asm is not the
common case.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
---
arch/arm/include/asm/assembler.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 860256c..ec869e9 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -403,4 +403,10 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
")"
#endif /* ! __ASSEMBLY__ */
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define __asm_cpu_to_le32(x) __asm_swab32(x)
+#else
+#define __asm_cpu_to_le32(x) "(" x ")"
+#endif
+
#endif /* __ASM_ASSEMBLER_H__ */
--
1.7.9.5
next prev parent reply other threads:[~2013-10-09 14:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-09 14:29 [RFC PATCH 0/4] ARM: Unify const-swabbing and conditional asm Dave Martin
2013-10-09 14:29 ` [RFC PATCH 1/4] ARM: Allow assembler.h to be used with inline asm Dave Martin
2013-10-09 14:42 ` Russell King - ARM Linux
2013-10-09 15:00 ` Dave Martin
2013-10-09 15:32 ` Nicolas Pitre
2013-10-09 14:29 ` [RFC PATCH 2/4] ARM: Add common compile-time swab32 for asm code Dave Martin
2013-10-09 14:29 ` Dave Martin [this message]
2013-10-09 14:29 ` [RFC PATCH 4/4] drivers/bus: arm-cci: Fix CCI enable code for BE32 Dave Martin
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