From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Optimize memcpy_{from,to}io() and memset_io() by transferring in
64 bit as much as possible with minimized barrier usage. This
simplest optimization brings faster throughput compare to current
byte-by-byte read and write with barrier in the loop. Code's
skeleton is taken from the powerpc & arm64.
Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
---
arch/csky/include/asm/io.h | 11 +++++
arch/csky/kernel/io.c | 91 ++++++++++++++++++++++++++++++++++++++
2 files changed, 102 insertions(+)
create mode 100644 arch/csky/kernel/io.c
diff --git a/arch/csky/include/asm/io.h b/arch/csky/include/asm/io.h
index f82654053dc0..adb64e26194f 100644
--- a/arch/csky/include/asm/io.h
+++ b/arch/csky/include/asm/io.h
@@ -32,6 +32,17 @@
#define writel(v,c) ({ wmb(); writel_relaxed((v),(c)); mb(); })
#endif
+/*
+ * String version of I/O memory access operations.
+ */
+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);
+
+#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))
+
/*
* I/O memory mapping functions.
*/
diff --git a/arch/csky/kernel/io.c b/arch/csky/kernel/io.c
new file mode 100644
index 000000000000..5883f13fa2b1
--- /dev/null
+++ b/arch/csky/kernel/io.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/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, 4)) {
+ *(u8 *)to = __raw_readb(from);
+ from++;
+ to++;
+ count--;
+ }
+
+ while (count >= 4) {
+ *(u32 *)to = __raw_readl(from);
+ from += 4;
+ to += 4;
+ count -= 4;
+ }
+
+ 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, 4)) {
+ __raw_writeb(*(u8 *)from, to);
+ from++;
+ to++;
+ count--;
+ }
+
+ while (count >= 4) {
+ __raw_writel(*(u32 *)from, to);
+ from += 4;
+ to += 4;
+ count -= 4;
+ }
+
+ 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)
+{
+ u32 qc = (u8)c;
+
+ qc |= qc << 8;
+ qc |= qc << 16;
+
+ while (count && !IS_ALIGNED((unsigned long)dst, 4)) {
+ __raw_writeb(c, dst);
+ dst++;
+ count--;
+ }
+
+ while (count >= 4) {
+ __raw_writel(qc, dst);
+ dst += 4;
+ count -= 4;
+ }
+
+ while (count) {
+ __raw_writeb(c, dst);
+ dst++;
+ count--;
+ }
+}
+EXPORT_SYMBOL(__memset_io);
--
2.25.1
