[PATCH v2 3/3] arm64: use generic MMIO accessors

[Qingfang Deng <qingfang.deng@linux.dev>]

Use the generic raw write accessors in place of the inline assembly
stores. Include asm-generic/mmio.h after the arm64 ordering hooks so
these accessors are also available to the write-combining helpers
before asm-generic/io.h is included.

Retain the raw read overrides when either the Cortex-A57 erratum 832075
or NVIDIA Olympus erratum 1027 workaround is configured. This preserves
the alternative-patched load-acquire instructions and pre-load barriers.
Use generic raw reads when neither workaround is enabled.

Assisted-by: Codex:gpt-6-astra
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
---
v2: new patch
---
 arch/arm64/include/asm/io.h | 37 ++++++-------------------------------
 1 file changed, 6 insertions(+), 31 deletions(-)

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 49a7002661a9..2fdac25bc31b 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -19,37 +19,9 @@
 #include <asm/cpufeature.h>
 #include <asm/rsi.h>
 
-/*
- * Generic IO read/write.  These perform native-endian accesses.
- */
-#define __raw_writeb __raw_writeb
-static __always_inline void __raw_writeb(u8 val, volatile void __iomem *addr)
-{
-	volatile u8 __iomem *ptr = addr;
-	asm volatile("strb %w0, %1" : : "rZ" (val), "Qo" (*ptr));
-}
-
-#define __raw_writew __raw_writew
-static __always_inline void __raw_writew(u16 val, volatile void __iomem *addr)
-{
-	volatile u16 __iomem *ptr = addr;
-	asm volatile("strh %w0, %1" : : "rZ" (val), "Qo" (*ptr));
-}
-
-#define __raw_writel __raw_writel
-static __always_inline void __raw_writel(u32 val, volatile void __iomem *addr)
-{
-	volatile u32 __iomem *ptr = addr;
-	asm volatile("str %w0, %1" : : "rZ" (val), "Qo" (*ptr));
-}
-
-#define __raw_writeq __raw_writeq
-static __always_inline void __raw_writeq(u64 val, volatile void __iomem *addr)
-{
-	volatile u64 __iomem *ptr = addr;
-	asm volatile("str %x0, %1" : : "rZ" (val), "Qo" (*ptr));
-}
-
+#if defined(CONFIG_ARM64_ERRATUM_832075) || \
+	defined(CONFIG_NVIDIA_OLYMPUS_1027_ERRATUM)
+/* Keep the raw read overrides for the device-load erratum alternatives. */
 #define __raw_readb __raw_readb
 static __always_inline u8 __raw_readb(const volatile void __iomem *addr)
 {
@@ -102,6 +74,7 @@ static __always_inline u64 __raw_readq(const volatile void __iomem *addr)
 		     : "=r" (val) : "r" (addr));
 	return val;
 }
+#endif
 
 /* IO barriers */
 #define __io_ar(v)							\
@@ -125,6 +98,8 @@ static __always_inline u64 __raw_readq(const volatile void __iomem *addr)
 #define __io_br(v)
 #define __io_aw(v)
 
+#include <asm-generic/mmio.h>
+
 /* arm64-specific, don't use in portable drivers */
 #define __iormb(v)		__io_ar(v)
 #define __iowmb()		__io_bw()
-- 
2.43.0