Re: MPC5200 + LocalPlus Bus + memcpy

[Andrey Volkov <avolkov@varma-el.com>]

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Hello, Sascha.

On Wednesday, April 5, 2006, Sascha Hauer wrote:

> Hi all,

> I try to use jffs2 on a flash device connected to the mpc5200
> LocalPlus Bus. This bus does not allow misaligned accesses.
> The jffs2 code uses memcpy to copy from a word aligned address to an
> odd address. The ppc memcpy implementation first copies three bytes to get
> the target address word aligned, but then the source address is on an
> odd address. The following word accesses on this unaligned address fail
> badly.
Invalid crc on 'name' field ;)?

> I have fixed my problem by modifying the physmap mtd driver, but some
> day someone wants to connect SRAM to the LocalPlus Bus and I guess he
> will expect memcpy to work.
Heh, I'll have same problem. Patch (dirty hack)
attached (vs head of vanilla 2.6. tree)

> (BTW the arm implementation of memcpy seems to work around this problem)
Wrong, memcpy to/from SDRAM _may_ be unaligned, only
memcpy_fromio/memcpy_toio _must_ be aligned to even addresses.

P.S.
Paul, Sylvain, any suggestions to fix it?
AFAIK, memcpy_to/from_io must be it string.s, isn't it?

P.P.S Sacha if you start to write mscan driver, then please wait a
week, I planned to send my work to can-socket at next Friday.

-- 
Regards,
Andrey Volkov

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diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index cf55b22..3bf61d6 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -831,7 +831,7 @@ static int jffs2_scan_dirent_node(struct
 	if (!fd) {
 		return -ENOMEM;
 	}
-	memcpy(&fd->name, rd->name, rd->nsize);
+	memcpy_fromio(&fd->name, rd->name, rd->nsize);
 	fd->name[rd->nsize] = 0;
 
 	crc = crc32(0, fd->name, rd->nsize);
diff --git a/include/asm-ppc/io.h b/include/asm-ppc/io.h
index b919d8f..c2f173a 100644
--- a/include/asm-ppc/io.h
+++ b/include/asm-ppc/io.h
@@ -354,6 +354,29 @@ extern void _outsl_ns(volatile u32 __iom
 #define memset_io(a,b,c)       memset((void *)(a),(b),(c))
 #define memcpy_fromio(a,b,c)   memcpy((a),(void *)(b),(c))
 #define memcpy_toio(a,b,c)     memcpy((void *)(a),(b),(c))
+#elif defined (CONFIG_PPC_MPC52xx)
+static inline void memset_io(volatile void __iomem *addr, unsigned char val, int count)
+{
+	volatile u8 __iomem *addr_u8 = addr;
+	for(;count>0;count--)
+		*addr_u8++ = val;
+}
+
+static inline void memcpy_fromio(void *dst,const volatile void __iomem *src, int count)
+{
+	const volatile u8 __iomem *src_u8 = src;
+	u8 *dst_u8 = dst;
+	for(;count>0;count--)
+		*dst_u8++ = *src_u8++;
+}
+
+static inline void memcpy_toio(volatile void __iomem *dst, const void *src, int count)
+{
+	const u8 *src_u8 = src;
+	volatile u8 __iomem *dst_u8 = dst;
+	for(;count>0;count--)
+		*dst_u8++ = *src_u8++;
+}
 #else
 static inline void memset_io(volatile void __iomem *addr, unsigned char val, int count)
 {