[U-Boot-Users] RTC for MPC5200
wd at denx.de
Thu Jan 8 23:56:52 CET 2004
In message <20040108210501.GA4693 at timension.com> you wrote:
> Good morning. I have a couple of questions. After struggling with an initrd
What exactly is the problem? The procedure is fairly well documented
in the DULG, and a ready-to-run image is supplied with the ELDK. Just
> boot for a few days, I said "heck with it" and just made /dev/hda2 my root
> device. Given that the kernel is in flash, and the devices I need are
> compiled in (and I don't have module support), is there any reason to
> mess around with an initrd-style boot, given that we absolutely know
> what the hardware config is going to be? It works like a charm with the
A ramdisk image (loaded from flash) is one way to provide an embedded
system that is 100% bullet-proof agains unexpected reboots or
> default DENX Sys-V init, from the ppc-82xx tree, by the way, though I will
> have to prune some services.
Also, a more leaner setup like the busybox-based SELF used for our
defualt ramdisk images boots much, much faster than the full-blown
SysV init stuff.
> The other question regards the real time clock on the MPC5200. Unless I am
> seriously overlooking something, this does not appear to be implemented, yet,
> yes? The register structure doesn't look too arcane. Is anybody working on
> this? I am tempted, but nobody wants to roll in code from a rank novice. The
You will not be judged by years of experience, or by any
certificates. It's just the quality of the code that matters :-)
Seriously: don't worry, just go on, do it, and submit a patch. If it
needs improvements somebody else will help.
> project we're working on needs a self-contained clock. I notice that u-boot
> provides rtc services, but isn't that more properly a kernel function? I'm
> a little fuzzy on the dividing line.
Support for the RTC is not exactly needed in U-Boot. But it is very
convenient. It is much easier to debug in U-Boot, and you can just
test in the firmware if the RTC is really running iunstead of
debugging a Linux device driver. Also, the clock on some RTCs needs
to get started before you can use them. Not all Linux drivers do
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