[U-Boot] [PATCH] MPC512x: workaround data corruption for unaligned local bus accesses

[Joakim Tjernlund]

>
> Wolfgang Denk <wd at denx.de> wrote on 2010/06/29 14:55:44:
> >
> > Dear Joakim Tjernlund,
> >
> > In message <OFEB4E68BC.F6B8C9D0-ONC1257751.0045AE08-C1257751.
> > 0045DA56 at transmode.se> you wrote:
> > >
> > > > I could not come up with a better name... What is "align32wrap"
> > > > supposed to mean?
> > >
> > > mpc5200_memcpy_fromio() resp. mpc5200_memcpy_toio()?
> >
> > No. It's not only MPC5200, but also MPC521x. It's not I/O in general,
> > but only I/O from the Local Bus. And even then only unaliged read
> > access.
> >
> > But memcpy_for_unaligned_read_from_local_bus() was too long for me,
> > and memcpy_furflb() too cryptic ;-)
>
> memcpy_align_src()?
>
>    Jocke

BTW, perhaps this memcpy I wrote for uClibc long time ago
is useful? You can easily change dst or src alignment:

void *memcpy(void *to, const void *from, size_t len)
{
	unsigned long rem, chunks, tmp1, tmp2;
	unsigned char *tmp_to;
	unsigned char *tmp_from = (unsigned char *)from;

	chunks = len / 8;
	tmp_from -= 4;
	tmp_to = to - 4;
	if (!chunks)
		goto lessthan8;
	rem = (unsigned long )tmp_to % 4;
	if (rem)
		goto align;
 copy_chunks:
	do {
		/* make gcc to load all data, then store it */
		tmp1 = *(unsigned long *)(tmp_from+4);
		tmp_from += 8;
		tmp2 = *(unsigned long *)tmp_from;
		*(unsigned long *)(tmp_to+4) = tmp1;
		tmp_to += 8;
		*(unsigned long *)tmp_to = tmp2;
	} while (--chunks);
 lessthan8:
	len = len % 8;
	if (len >= 4) {
		tmp_from += 4;
		tmp_to += 4;
		*(unsigned long *)(tmp_to) = *(unsigned long *)(tmp_from);
		len -= 4;
	}
	if (!len)
		return to;
	tmp_from += 3;
	tmp_to += 3;
	do {
		*++tmp_to = *++tmp_from;
	} while (--len);

	return to;
 align:
	/* ???: Do we really need to generate the carry flag here? If not, then:
	rem -= 4; */
	rem = 4 - rem;
	len -= rem;
	do {
		*(tmp_to+4) = *(tmp_from+4);
		++tmp_from;
		++tmp_to;
	} while (--rem);
	chunks = len / 8;
	if (chunks)
		goto copy_chunks;
	goto lessthan8;
}