sh: Optimise memcpy_to/fromio for SH4

Optimise memcpy_to/fromio. This is used extensivly by MTD, so is a
worthwhile performance gain. The main savings come from not repeatedly
calling readl/writel, and doing word instead of byte at a time
transfers. Also using "movca.l" on SH4 gives a small performance win.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 72 insertions, 21 deletions

diff --git a/arch/sh/kernel/io.c b/arch/sh/kernel/io.c
index d0ca968..4770c24 100644
--- a/arch/sh/kernel/io.c
+++ b/arch/sh/kernel/io.c
@@ -1,12 +1,9 @@
 /*
- * linux/arch/sh/kernel/io.c
+ * arch/sh/kernel/io.c - Machine independent I/O functions.
  *
- * Copyright (C) 2000  Stuart Menefy
+ * Copyright (C) 2000 - 2009  Stuart Menefy
  * Copyright (C) 2005  Paul Mundt
  *
- * Provide real functions which expand to whatever the header file defined.
- * Also definitions of machine independent IO functions.
- *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
@@ -18,33 +15,87 @@
 
 /*
  * 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, unsigned long count)
 {
-	unsigned char *p = to;
-        while (count) {
-                count--;
-                *p = readb(from);
-                p++;
-                from++;
-        }
+	/*
+	 * Would it be worthwhile doing byte and long transfers first
+	 * to try and get aligned?
+	 */
+#ifdef CONFIG_CPU_SH4
+	if ((count >= 0x20) &&
+	     (((u32)to & 0x1f) == 0) && (((u32)from & 0x3) == 0)) {
+		int tmp2, tmp3, tmp4, tmp5, tmp6;
+
+		__asm__ __volatile__(
+			"1:			\n\t"
+			"mov.l	@%7+, r0	\n\t"
+			"mov.l	@%7+, %2	\n\t"
+			"movca.l r0, @%0	\n\t"
+			"mov.l	@%7+, %3	\n\t"
+			"mov.l	@%7+, %4	\n\t"
+			"mov.l	@%7+, %5	\n\t"
+			"mov.l	@%7+, %6	\n\t"
+			"mov.l	@%7+, r7	\n\t"
+			"mov.l	@%7+, r0	\n\t"
+			"mov.l	%2, @(0x04,%0)	\n\t"
+			"mov	#0x20, %2	\n\t"
+			"mov.l	%3, @(0x08,%0)	\n\t"
+			"sub	%2, %1		\n\t"
+			"mov.l	%4, @(0x0c,%0)	\n\t"
+			"cmp/hi	%1, %2		! T if 32 > count	\n\t"
+			"mov.l	%5, @(0x10,%0)	\n\t"
+			"mov.l	%6, @(0x14,%0)	\n\t"
+			"mov.l	r7, @(0x18,%0)	\n\t"
+			"mov.l	r0, @(0x1c,%0)	\n\t"
+			"bf.s	1b		\n\t"
+			" add	#0x20, %0	\n\t"
+			: "=&r" (to), "=&r" (count),
+			  "=&r" (tmp2), "=&r" (tmp3), "=&r" (tmp4),
+			  "=&r" (tmp5), "=&r" (tmp6), "=&r" (from)
+			: "7"(from), "0" (to), "1" (count)
+			: "r0", "r7", "t", "memory");
+	}
+#endif
+
+	if ((((u32)to | (u32)from) & 0x3) == 0) {
+		for (; count > 3; count -= 4) {
+			*(u32 *)to = *(volatile u32 *)from;
+			to += 4;
+			from += 4;
+		}
+	}
+
+	for (; count > 0; count--) {
+		*(u8 *)to = *(volatile u8 *)from;
+		to++;
+		from++;
+	}
+
+	mb();
 }
 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, unsigned long count)
 {
-	const unsigned char *p = from;
-        while (count) {
-                count--;
-                writeb(*p, to);
-                p++;
-                to++;
-        }
+	if ((((u32)to | (u32)from) & 0x3) == 0) {
+		for ( ; count > 3; count -= 4) {
+			*(volatile u32 *)to = *(u32 *)from;
+			to += 4;
+			from += 4;
+		}
+	}
+
+	for (; count > 0; count--) {
+		*(volatile u8 *)to = *(u8 *)from;
+		to++;
+		from++;
+	}
+
+	mb();
 }
 EXPORT_SYMBOL(memcpy_toio);