[PATCH v3 1/4] Consolidate __memcpy_{to,from}io and __memset_io into a single lib

[Julian Vetter]

Various architectures have almost the same implementations for
__memcpy_{to,from}io and __memset_io functions. So, consolidate them and
introduce a CONFIG_GENERIC_IO_COPY flag to build the given
lib/io_copy.c.

Reviewed-by: Yann Sionneau <ysionneau@xxxxxxxxxxxxx>
Signed-off-by: Julian Vetter <jvetter@xxxxxxxxxxxxx>
---
 lib/Kconfig   |   3 ++
 lib/Makefile  |   1 +
 lib/io_copy.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 114 insertions(+)
 create mode 100644 lib/io_copy.c

diff --git a/lib/Kconfig b/lib/Kconfig
index b38849af6f13..741550bc3856 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -70,6 +70,9 @@ source "lib/math/Kconfig"
 config NO_GENERIC_PCI_IOPORT_MAP
 	bool
 
+config GENERIC_IO_COPY
+	bool
+
 config GENERIC_IOMAP
 	bool
 	select GENERIC_PCI_IOMAP
diff --git a/lib/Makefile b/lib/Makefile
index 322bb127b4dc..4f56ad5f9ed6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -130,6 +130,7 @@ CFLAGS_debug_info.o += $(call cc-option, -femit-struct-debug-detailed=any)
 
 obj-y += math/ crypto/
 
+obj-$(CONFIG_GENERIC_IO_COPY) += io_copy.o
 obj-$(CONFIG_GENERIC_IOMAP) += iomap.o
 obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o
 obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o
diff --git a/lib/io_copy.c b/lib/io_copy.c
new file mode 100644
index 000000000000..f44583166325
--- /dev/null
+++ b/lib/io_copy.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * derived from arch/arm/kernel/io.c
+ *
+ * Copyright (C) 2024 Kalray Inc.
+ * Author(s): Julian Vetter
+ */
+
+#include <asm/unaligned.h>
+
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/io.h>
+
+#define NATIVE_STORE_SIZE	(BITS_PER_LONG/8)
+
+void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
+{
+	while (count && !IS_ALIGNED((unsigned long)from, NATIVE_STORE_SIZE)) {
+		*(u8 *)to = __raw_readb(from);
+		from++;
+		to++;
+		count--;
+	}
+
+	while (count >= NATIVE_STORE_SIZE) {
+#ifdef CONFIG_64BIT
+			put_unaligned(__raw_readq(from), (uintptr_t *)to);
+#else
+			put_unaligned(__raw_readl(from), (uintptr_t *)to);
+#endif
+
+		from += NATIVE_STORE_SIZE;
+		to += NATIVE_STORE_SIZE;
+		count -= NATIVE_STORE_SIZE;
+	}
+
+	while (count) {
+		*(u8 *)to = __raw_readb(from);
+		from++;
+		to++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(__memcpy_fromio);
+
+void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
+{
+	while (count && !IS_ALIGNED((unsigned long)to, NATIVE_STORE_SIZE)) {
+		__raw_writeb(*(u8 *)from, to);
+		from++;
+		to++;
+		count--;
+	}
+
+	while (count >= NATIVE_STORE_SIZE) {
+#ifdef CONFIG_64BIT
+			__raw_writeq(get_unaligned((uintptr_t *)from), to);
+#else
+			__raw_writel(get_unaligned((uintptr_t *)from), to);
+#endif
+
+		from += NATIVE_STORE_SIZE;
+		to += NATIVE_STORE_SIZE;
+		count -= NATIVE_STORE_SIZE;
+	}
+
+	while (count) {
+		__raw_writeb(*(u8 *)from, to);
+		from++;
+		to++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(__memcpy_toio);
+
+void __memset_io(volatile void __iomem *dst, int c, size_t count)
+{
+	uintptr_t qc = (u8)c;
+
+	qc |= qc << 8;
+	qc |= qc << 16;
+
+	if (IS_ENABLED(CONFIG_64BIT))
+		qc |= qc << 32;
+
+	while (count && !IS_ALIGNED((unsigned long)dst, NATIVE_STORE_SIZE)) {
+		__raw_writeb(c, dst);
+		dst++;
+		count--;
+	}
+
+	while (count >= NATIVE_STORE_SIZE) {
+#ifdef CONFIG_64BIT
+			__raw_writeq(qc, dst);
+#else
+			__raw_writel(qc, dst);
+#endif
+
+		dst += NATIVE_STORE_SIZE;
+		count -= NATIVE_STORE_SIZE;
+	}
+
+	while (count) {
+		__raw_writeb(c, dst);
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(__memset_io);
-- 
2.34.1