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ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

PATCH New Dave Martin 2 participants 3 messages Feb 4, 2011 – Feb 8, 2011 Arm (32-bit)

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Dave Martin

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PATCH 1/1 ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

Pre-v7 processors don't have wfe/sev, so these are defined for consistency as empty barrier asms.

For v6, wfi is architected as a defined MCR instruction, so use that definition.

Doing a no-op instead of wfi() is probably bad, so for older processors than v6, wfi() is not defined. If needed, some CPU- specific wfi() will have to be defined elsewhere.

Signed-off-by Dave Martin <[email protected]>
---
 arch/arm/include/asm/system.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
arch/arm/include/asm/system.h +7 -0
index 97f6d60..0e1cae3 100644
@@ -129,7 +129,14 @@ extern unsigned int user_debug;
 #define sev()	__asm__ __volatile__ ("sev" : : : "memory")
 #define wfe()	__asm__ __volatile__ ("wfe" : : : "memory")
 #define wfi()	__asm__ __volatile__ ("wfi" : : : "memory")
+#else /* __LINUX_ARM_ARCH__ < 7 */
+#define sev()	__asm__ __volatile__ ("" : : : "memory")
+#define wfe()	__asm__ __volatile__ ("" : : : "memory")
+#if __LINUX_ARM_ARCH__ == 6
+#define wfi()	__asm__ __volatile__ ("mcr p15, 0, %0, c7, c5, 4" \
+					: : "r" (0) : "memory")
 #endif
+#endif /* __LINUX_ARM_ARCH__ < 7 */
 
 #if __LINUX_ARM_ARCH__ >= 7
 #define isb() __asm__ __volatile__ ("isb" : : : "memory")
Signature · 1 line
1.7.1
#1 lore raw

PATCH 1/1 ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

Dave,

Quoted 30 lines

-----Original Message-----
From: Dave Martin [mailto:dave.martin at linaro.org]
Sent: Friday, February 04, 2011 7:51 PM
To: linux-arm-kernel at lists.infradead.org
Cc: Dave Martin; Tony Lindgren; Santosh Shilimkar; Jean Pihet; linux-omap at vger.kernel.org; Nicolas Pitre; Russell King
Subject: [PATCH] ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

Pre-v7 processors don't have wfe/sev, so these are defined for consistency as empty barrier asms.

For v6, wfi is architected as a defined MCR instruction, so use that definition.

Doing a no-op instead of wfi() is probably bad, so for older processors than v6, wfi() is not defined. If needed, some CPU- specific wfi() will have to be defined elsewhere.

Signed-off-by Dave Martin <[email protected]>
---
 arch/arm/include/asm/system.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
arch/arm/include/asm/system.h +0 -0
index 97f6d60..0e1cae3 100644

arch/arm/include/asm/system.h extern unsigned int user_debug; · line 134

Quoted 6 lines
arch/arm/include/asm/system.h +3 -0
@@ -129,7 +129,14 @@ extern unsigned int user_debug;
 #define sev()	__asm__ __volatile__ ("sev" : : : "memory")
 #define wfe()	__asm__ __volatile__ ("wfe" : : : "memory")
 #define wfi()	__asm__ __volatile__ ("wfi" : : : "memory")
+#else /* __LINUX_ARM_ARCH__ < 7 */
+#define sev()	__asm__ __volatile__ ("" : : : "memory")
+#define wfe()	__asm__ __volatile__ ("" : : : "memory")

This is not true for "CPU_32v6K" extensions, right. I think they do support 'sev' and 'wfe' instructions.

Quoted 11 lines
arch/arm/include/asm/system.h +4 -0
+#if __LINUX_ARM_ARCH__ == 6
+#define wfi()	__asm__ __volatile__ ("mcr p15, 0, %0, c7, c5, 4"
 \
+					: : "r" (0) : "memory")
 #endif
+#endif /* __LINUX_ARM_ARCH__ < 7 */
 
 #if __LINUX_ARM_ARCH__ >= 7

#define isb() __asm__ __volatile__ ("isb" : : : "memory")
--
1.7.1

#2 lore raw

PATCH 1/1 ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

Quoted 34 lines

-----Original Message-----
From: Santosh Shilimkar [mailto:santosh.shilimkar at ti.com]
Sent: Tuesday, February 08, 2011 2:11 PM
To: 'Dave Martin'; 'linux-arm-kernel at lists.infradead.org'
Cc: 'Tony Lindgren'; Jean Pihet-XID; 'linux-omap at vger.kernel.org'; 'Nicolas Pitre'; 'Russell King'
Subject: RE: [PATCH] ARM: Define wfi(), wfe(), sev() macros for pre- v7 processors

Dave,

Quoted 24 lines

-----Original Message-----
From: Dave Martin [mailto:dave.martin at linaro.org]
Sent: Friday, February 04, 2011 7:51 PM
To: linux-arm-kernel at lists.infradead.org
Cc: Dave Martin; Tony Lindgren; Santosh Shilimkar; Jean Pihet; linux-omap at vger.kernel.org; Nicolas Pitre; Russell King
Subject: [PATCH] ARM: Define wfi(), wfe(), sev() macros for pre-v7 processors

Pre-v7 processors don't have wfe/sev, so these are defined for consistency as empty barrier asms.

For v6, wfi is architected as a defined MCR instruction, so use that definition.

Doing a no-op instead of wfi() is probably bad, so for older processors than v6, wfi() is not defined. If needed, some CPU- specific wfi() will have to be defined elsewhere.

Signed-off-by Dave Martin <[email protected]>
---
 arch/arm/include/asm/system.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
Quoted 16 lines

arch/arm/include/asm/system.h extern unsigned int user_debug; · line 134

Quoted 12 lines
arch/arm/include/asm/system.h +3 -0
index 97f6d60..0e1cae3 100644
@@ -129,7 +129,14 @@ extern unsigned int user_debug;
 #define sev()	__asm__ __volatile__ ("sev" : : : "memory")
 #define wfe()	__asm__ __volatile__ ("wfe" : : : "memory")
 #define wfi()	__asm__ __volatile__ ("wfi" : : : "memory")
+#else /* __LINUX_ARM_ARCH__ < 7 */
+#define sev()	__asm__ __volatile__ ("" : : : "memory")
+#define wfe()	__asm__ __volatile__ ("" : : : "memory")

This is not true for "CPU_32v6K" extensions, right. I think they do support 'sev' and 'wfe' instructions.

Ignore the comment. 'CPU_32v6K' is already considered.