New implementation for IO memcpy and IO memset

The IO memcpy and IO memset functions in asm-generic/io.h simply call
memcpy and memset. This can lead to alignment problems or faults on
architectures that do not define their own version and fall back to
these defaults.
This patch introduces new implementations for IO memcpy and IO memset,
that use read{l,q} accessor functions, align accesses to machine word
size, and resort to byte accesses when the target memory is not aligned.
For new architectures and existing ones that were using the old
fallbacks these functions are save to use, because IO memory constraints
are taken into account. Moreover, architectures with similar
implementations can now use these new versions, not needing to implement
their own.

Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/asm-generic/io.h

@@ -1211,7 +1211,6 @@ static inline void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
 #endif
 
 #ifndef memset_io
-#define memset_io memset_io
 /**
  * memset_io	Set a range of I/O memory to a constant value
  * @addr:	The beginning of the I/O-memory range to set
@@ -1220,15 +1219,10 @@ static inline void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  *
  * Set a range of I/O memory to a given value.
  */
-static inline void memset_io(volatile void __iomem *addr, int value,
+void memset_io(volatile void __iomem *addr, int val, size_t count);
-			     size_t size)
-{
-	memset(__io_virt(addr), value, size);
-}
 #endif
 
 #ifndef memcpy_fromio
-#define memcpy_fromio memcpy_fromio
 /**
  * memcpy_fromio	Copy a block of data from I/O memory
  * @dst:		The (RAM) destination for the copy
@@ -1237,16 +1231,10 @@ static inline void memset_io(volatile void __iomem *addr, int value,
  *
  * Copy a block of data from I/O memory.
  */
-static inline void memcpy_fromio(void *buffer,
+void memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count);
-				 const volatile void __iomem *addr,
-				 size_t size)
-{
-	memcpy(buffer, __io_virt(addr), size);
-}
 #endif
 
 #ifndef memcpy_toio
-#define memcpy_toio memcpy_toio
 /**
  * memcpy_toio		Copy a block of data into I/O memory
  * @dst:		The (I/O memory) destination for the copy
@@ -1255,11 +1243,7 @@ static inline void memcpy_fromio(void *buffer,
  *
  * Copy a block of data to I/O memory.
  */
-static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer,
+void memcpy_toio(volatile void __iomem *dst, const void *src, size_t count);
-			       size_t size)
-{
-	memcpy(__io_virt(addr), buffer, size);
-}
 #endif
 
 extern int devmem_is_allowed(unsigned long pfn);

lib/Makefile

@@ -35,7 +35,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
 	 earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
 	 nmi_backtrace.o win_minmax.o memcat_p.o \
-	 buildid.o objpool.o union_find.o
+	 buildid.o objpool.o union_find.o iomem_copy.o
 
 lib-$(CONFIG_PRINTK) += dump_stack.o
 lib-$(CONFIG_SMP) += cpumask.o

lib/iomem_copy.c

@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2024 Kalray, Inc.  All Rights Reserved.
+ */
+
+#include <linux/align.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+
+#ifndef memset_io
+/**
+ * memset_io		Set a range of I/O memory to a constant value
+ * @addr:		The beginning of the I/O-memory range to set
+ * @val:		The value to set the memory to
+ * @count:		The number of bytes to set
+ *
+ * Set a range of I/O memory to a given value.
+ */
+void memset_io(volatile void __iomem *addr, int val, size_t count)
+{
+	long qc = (u8)val;
+
+	qc *= ~0UL / 0xff;
+
+	while (count && !IS_ALIGNED((long)addr, sizeof(long))) {
+		__raw_writeb(val, addr);
+		addr++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+#ifdef CONFIG_64BIT
+		__raw_writeq(qc, addr);
+#else
+		__raw_writel(qc, addr);
+#endif
+
+		addr += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		__raw_writeb(val, addr);
+		addr++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memset_io);
+#endif
+
+#ifndef memcpy_fromio
+/**
+ * memcpy_fromio	Copy a block of data from I/O memory
+ * @dst:		The (RAM) destination for the copy
+ * @src:		The (I/O memory) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data from I/O memory.
+ */
+void memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count)
+{
+	while (count && !IS_ALIGNED((long)src, sizeof(long))) {
+		*(u8 *)dst = __raw_readb(src);
+		src++;
+		dst++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+#ifdef CONFIG_64BIT
+		long val = __raw_readq(src);
+#else
+		long val = __raw_readl(src);
+#endif
+		put_unaligned(val, (long *)dst);
+
+
+		src += sizeof(long);
+		dst += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		*(u8 *)dst = __raw_readb(src);
+		src++;
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_fromio);
+#endif
+
+#ifndef memcpy_toio
+/**
+ * memcpy_toio		Copy a block of data into I/O memory
+ * @dst:		The (I/O memory) destination for the copy
+ * @src:		The (RAM) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data to I/O memory.
+ */
+void memcpy_toio(volatile void __iomem *dst, const void *src, size_t count)
+{
+	while (count && !IS_ALIGNED((long)dst, sizeof(long))) {
+		__raw_writeb(*(u8 *)src, dst);
+		src++;
+		dst++;
+		count--;
+	}
+
+	while (count >= sizeof(long)) {
+		long val = get_unaligned((long *)src);
+#ifdef CONFIG_64BIT
+		__raw_writeq(val, dst);
+#else
+		__raw_writel(val, dst);
+#endif
+
+		src += sizeof(long);
+		dst += sizeof(long);
+		count -= sizeof(long);
+	}
+
+	while (count) {
+		__raw_writeb(*(u8 *)src, dst);
+		src++;
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_toio);
+#endif
+
+