Re: [rtc-linux] Re: [PATCH/RFC 0/5] Generic RTC class driver

Geert Uytterhoeven
2009-02-25T09:59:42Z

On Tue, 24 Feb 2009, Brad Boyer wrote:
> On Tue, Feb 24, 2009 at 07:37:08PM +0100, Alessandro Zummo wrote:
> > On Tue, 24 Feb 2009 18:56:03 +0100 (CET)
> > Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> wrote:
> > > Converting all (ca. 20?) ppc and m68k RTC support code into individual RTC
> > > class drivers would add ca. 100+ lines of code for each individual driver.
> >
> > How different are all of those boards? It's simply a matter
> > of parameters and offsets? can we group them somehow?
>
> I imagine we could cut down the numbers somewhat with clever code sharing,
> but it's still going to be a fairly large number. I don't know all the
> embedded boards, but just with all the Macintosh models there are at
> least three and maybe four drastically different methods of RTC access,
> and all of them are directly tied to some chip that does something else
> completely unrelated. For one of them we don't even have a driver at the

Yeah, on Mac/m68k the RTC is usually handled by a chip that does lots of other
things, so you need to keep the bulk of the code in arch/m68k/ anyway.

> moment. They also are all custom chips that wouldn't be used anywhere
> else. The other thing we need to keep in mind is that if we do it right
> we can share drivers across m68k and powerpc in some cases. I imagine
> some of the embedded powerpc boards are using chips that are common in
> other architectures as well.

Many embedded powerpc boards already have RTC class drivers under drivers/rtc/,
as their RTC chips are sufficiently common.

The ones that don't are mostly "workstation" or "server" type hardware. The
full list is:
- rtas_set_rtc_time
- mpc8xx_set_rtc_time
- beat_get_rtc_time
- chrp_set_rtc_time
- iSeries_set_rtc_time
- maple_set_rtc_time
- pmac_set_rtc_time
- ps3_set_rtc_time

With kind regards,

Geert Uytterhoeven
Software Architect

Sony Techsoft Centre Europe
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