linux-kernel - [PATCH] arm: Remove IO memcpy for Big-Endian

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Message-Id: <20241203083838.3260036-1-jvetter@outer-limits.org>
Date: Tue,  3 Dec 2024 09:38:38 +0100
From: Julian Vetter <jvetter@...er-limits.org>
To: Arnd Bergmann <arnd@...db.de>,
	Russell King <linux@...linux.org.uk>
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Julian Vetter <julian@...er-limits.org>
Subject: [PATCH] arm: Remove IO memcpy for Big-Endian

From: Julian Vetter <julian@...er-limits.org>

Recently a new IO memcpy was added in libs/iomem_copy.c. So, remove the
byte-wise IO memcpy operations used in ARM big endian builds and fall
back to the new generic implementation. It will be slightly faster,
because it uses machine word accesses if the memory is aligned and falls
back to byte-wise accesses if its not.

Signed-off-by: Julian Vetter <julian@...er-limits.org>
---
 arch/arm/include/asm/io.h | 11 ----------
 arch/arm/kernel/io.c      | 46 ---------------------------------------
 2 files changed, 57 deletions(-)

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 1815748f5d2a..146509d82e30 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -253,13 +253,6 @@ void __iomem *pci_remap_cfgspace(resource_size_t res_cookie, size_t size);
 #define insl(p,d,l)		__raw_readsl(__io(p),d,l)
 #endif
 
-/*
- * String version of IO memory access ops:
- */
-extern void _memcpy_fromio(void *, const volatile void __iomem *, size_t);
-extern void _memcpy_toio(volatile void __iomem *, const void *, size_t);
-extern void _memset_io(volatile void __iomem *, int, size_t);
-
 /*
  *  Memory access primitives
  *  ------------------------
@@ -322,10 +315,6 @@ static inline void memcpy_toio(volatile void __iomem *to, const void *from,
 }
 #define memcpy_toio(to,from,count) memcpy_toio(to,from,count)
 
-#else
-#define memset_io(c,v,l)	_memset_io(c,(v),(l))
-#define memcpy_fromio(a,c,l)	_memcpy_fromio((a),c,(l))
-#define memcpy_toio(c,a,l)	_memcpy_toio(c,(a),(l))
 #endif
 
 #endif	/* readl */
diff --git a/arch/arm/kernel/io.c b/arch/arm/kernel/io.c
index 60b621295d6c..afa4eff8c6c5 100644
--- a/arch/arm/kernel/io.c
+++ b/arch/arm/kernel/io.c
@@ -37,49 +37,3 @@ void atomic_io_modify(void __iomem *reg, u32 mask, u32 set)
 	raw_spin_unlock_irqrestore(&__io_lock, flags);
 }
 EXPORT_SYMBOL(atomic_io_modify);
-
-/*
- * Copy data from IO memory space to "real" memory space.
- * This needs to be optimized.
- */
-void _memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
-{
-	unsigned char *t = to;
-	while (count) {
-		count--;
-		*t = readb(from);
-		t++;
-		from++;
-	}
-}
-EXPORT_SYMBOL(_memcpy_fromio);
-
-/*
- * Copy data from "real" memory space to IO memory space.
- * This needs to be optimized.
- */
-void _memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
-{
-	const unsigned char *f = from;
-	while (count) {
-		count--;
-		writeb(*f, to);
-		f++;
-		to++;
-	}
-}
-EXPORT_SYMBOL(_memcpy_toio);
-
-/*
- * "memset" on IO memory space.
- * This needs to be optimized.
- */
-void _memset_io(volatile void __iomem *dst, int c, size_t count)
-{
-	while (count) {
-		count--;
-		writeb(c, dst);
-		dst++;
-	}
-}
-EXPORT_SYMBOL(_memset_io);
-- 
2.34.1