[U-Boot] [PATCH v4 07/13] regmap: Add raw read/write functions

[Mario Six]

On Tue, Aug 7, 2018 at 4:31 PM Daniel Schwierzeck
<daniel.schwierzeck at gmail.com> wrote:
>
> 2018-08-07 9:36 GMT+02:00 Mario Six <mario.six at gdsys.cc>:
> > Hi Anatolij,
> > On Mon, Aug 6, 2018 at 9:12 PM Anatolij Gustschin <agust at denx.de> wrote:
> >>
> >> Hi Mario,
> >>
> >> On Fri,  3 Aug 2018 10:01:12 +0200
> >> Mario Six mario.six at gdsys.cc wrote:
> >> ...
> >> > +int regmap_raw_read(struct regmap *map, uint offset, void *valp, size_t val_len)
> >> > +{
> >> > +     void *ptr;
> >> > +
> >> > +     ptr = map_physmem(map->ranges[0].start + offset, val_len, MAP_NOCACHE);
> >> > +
> >> > +     switch (val_len) {
> >> > +     case REGMAP_SIZE_8:
> >> > +             *((u8 *)valp) = in_8((u8 *)ptr);
> >> > +             break;
> >> > +     case REGMAP_SIZE_16:
> >> > +             *((u16 *)valp) = in_le16((u16 *)ptr);
> >> > +             break;
> >> > +     case REGMAP_SIZE_32:
> >> > +             *((u32 *)valp) = in_le32((u32 *)ptr);
> >>
> >> this breaks building for MIPS:
> >>
> >>   https://travis-ci.org/vdsao/u-boot-video/jobs/412722192#L869
> >>
> > I see. MIPS apparently doesn't implement any of the in/out functions at all.
> > But since the necessary __raw_read/__raw_write functions exist, it's just a
> > matter of a few lines to add them. I'll add a patch that will fix this.
>
> why don't you directly use readb(), readw(), readl() etc.? What about
> 64 Bit registers (readq())?
>

readb/readw/etc. are not endianness-safe, so the regmap functions would return
different values on a big-endian and a little-endian system for the same IC,
and since the vast majority of IC registers are little-endian, having LE as the
default seems reasonable. That does make it a bit more complicated to implement
drivers for big-endian register spaces (wrapping values in le*_to_cpu), but for
everything else the default will work as expected.

The 64-bit support is a good point. It could be added with a few lines, so if
it's needed I could.

> >
> > There also seems to be a warning about a format specifier on MIPS, I'll fix
> > that as well.
> >
> > To make things less confusing, I'll import your v5 of "misc: Sort Makefile
> > entries" and send a full v6 series.
> >
> >> Anatolij
> >
> > Best regards,
> > Mario
> >
> - Daniel
>

Best regards,
Mario