[OpenWrt-Devel] [PATCH 1/3] b53: add b53_mac_array_to_u64() utility function

[Alexandru Ardelean]

So, on a powerpc system this works.

static inline u64 b53_mac_array_to_u64(const u8 *u8_arr) {
    u64 mac = 0;
    u8 *cmac = (u8 *)&mac;
    memcpy(&cmac[2], u8_arr, 6);
    return mac;
}

I've done this approach initially, but there were some concerns afterwards
regarding endianness.
On my x86_64 system it looks ok, but I'm hoping you'd validate that this is
endian-correct and would work on little endian targets.
And then I'll move this in the port mirroring patch.

Thanks


On Fri, Feb 27, 2015 at 8:36 PM, Jonas Gorski <jogo at openwrt.org> wrote:

> Hi,
>
> On Mon, Feb 23, 2015 at 3:41 PM, Alexandru Ardelean
> <ardeleanalex at gmail.com> wrote:
> > From: Alexandru Ardelean <ardeleanalex at gmail.com>
> >
> > Converts an MAC array of u8 to a u64 value.
> >
> > Signed-off-by: Alexandru Ardelean <ardeleanalex at gmail.com>
> > ---
> >  target/linux/generic/files/drivers/net/phy/b53/b53_regs.h | 10
> ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/target/linux/generic/files/drivers/net/phy/b53/b53_regs.h
> b/target/linux/generic/files/drivers/net/phy/b53/b53_regs.h
> > index ba50915..4379c58 100644
> > --- a/target/linux/generic/files/drivers/net/phy/b53/b53_regs.h
> > +++ b/target/linux/generic/files/drivers/net/phy/b53/b53_regs.h
> > @@ -20,6 +20,16 @@
> >  #ifndef __B53_REGS_H
> >  #define __B53_REGS_H
> >
> > +/* Utility function for converting u8 arrays into u64 values to be
> written with b53_write */
>
> You only use this in b53_common.c, so why not just have it in there?
> And maybe merge it into the patch atually adding a user.
>
> > +static inline u64 b53_mac_array_to_u64(const u8 *u8_arr) {
> > +       u64 mac = (*(const u64 *)u8_arr);
>
> Also this will likely produce alignment issues on e.g. mips, which
> doesn't allow unaligned accesses.
>
> > +#ifdef __BIG_ENDIAN
> > +       return (mac >> 16);
> > +#else
> > +       return (mac << 16);
> > +#endif
> > +}
> > +
> >  /* Management Port (SMP) Page offsets */
> >  #define B53_CTRL_PAGE                  0x00 /* Control */
> >  #define B53_STAT_PAGE                  0x01 /* Status */
> > --
>
> Jonas
>
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