[PATCH] ARM64: Implement mem*_*io()

[Sascha Hauer]

This adds memset_io(), memcpy_fromio() and memcpy_toio(). These have not
been defined for ARM64 previously. The code is directly taken from the
Kernel.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/arm/lib64/Makefile |  2 +-
 arch/arm/lib64/io.c     | 98 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/lib64/io.c

diff --git a/arch/arm/lib64/Makefile b/arch/arm/lib64/Makefile
index 69cb3d8ea1..a004af4867 100644
--- a/arch/arm/lib64/Makefile
+++ b/arch/arm/lib64/Makefile
@@ -6,5 +6,5 @@ obj-$(CONFIG_ARM_OPTIMZED_STRING_FUNCTIONS)	+= memset.o string.o
 extra-y += barebox.lds
 obj-pbl-y   += runtime-offset.o
 obj-pbl-y   += setjmp.o
-
+obj-y += io.o
 pbl-y	+= div0.o pbl.o
diff --git a/arch/arm/lib64/io.c b/arch/arm/lib64/io.c
new file mode 100644
index 0000000000..fdf2117cc8
--- /dev/null
+++ b/arch/arm/lib64/io.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Based on arch/arm/kernel/io.c
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <io.h>
+
+/*
+ * Copy data from IO memory space to "real" memory space.
+ */
+void memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
+{
+	while (count && !IS_ALIGNED((unsigned long)from, 8)) {
+		*(u8 *)to = __raw_readb(from);
+		from++;
+		to++;
+		count--;
+	}
+
+	while (count >= 8) {
+		*(u64 *)to = __raw_readq(from);
+		from += 8;
+		to += 8;
+		count -= 8;
+	}
+
+	while (count) {
+		*(u8 *)to = __raw_readb(from);
+		from++;
+		to++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_fromio);
+
+/*
+ * Copy data from "real" memory space to IO memory space.
+ */
+void memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
+{
+	while (count && !IS_ALIGNED((unsigned long)to, 8)) {
+		__raw_writeb(*(u8 *)from, to);
+		from++;
+		to++;
+		count--;
+	}
+
+	while (count >= 8) {
+		__raw_writeq(*(u64 *)from, to);
+		from += 8;
+		to += 8;
+		count -= 8;
+	}
+
+	while (count) {
+		__raw_writeb(*(u8 *)from, to);
+		from++;
+		to++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memcpy_toio);
+
+/*
+ * "memset" on IO memory space.
+ */
+void memset_io(volatile void __iomem *dst, int c, size_t count)
+{
+	u64 qc = (u8)c;
+
+	qc |= qc << 8;
+	qc |= qc << 16;
+	qc |= qc << 32;
+
+	while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
+		__raw_writeb(c, dst);
+		dst++;
+		count--;
+	}
+
+	while (count >= 8) {
+		__raw_writeq(qc, dst);
+		dst += 8;
+		count -= 8;
+	}
+
+	while (count) {
+		__raw_writeb(c, dst);
+		dst++;
+		count--;
+	}
+}
+EXPORT_SYMBOL(memset_io);
-- 
2.29.2