Messages in this thread | | | Subject | sysfs for my chips | From | Benjamin Herrenschmidt <> | Date | Thu, 10 Oct 2013 15:19:48 +1100 |
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Hi Greg !
(random CC list of clueful people)
On some new powerpc platforms (non-hypervisor or rather linux is the hypervisor), I want to expose a bunch of stuff per "chip", the chips being currently the processor chips and the "centaurs" (think of them as the bottom half of the memory controllers).
Among other, I want a sysfs file in there to access "xscom" on the chip which is a sideband bus used for low level stuff (think jtag on steroid) which we can use, among others, for chip health monitoring, general debugging and diagnostics, etc...
I might add more such as VPD, model information, etc... later or at least a link to corresponding device-tree node.
How do you suggest I expose that ? So far I've been thinking about something like
/sys/chips/{processor,centaur}/chip#/files
or to avoid namespace clashes
/sys/firmware/chips/{processor,centaur}/chip#/files
Or maybe just
/sys/firmware/chips/chip#/files
(the chip type can be inferred from the chip#, they use the same space at least as far my firmware exposes them to Linux)
(the actual access to xscom goes via firmware tho it makes *some* sense)
But I could instead create platform devices corresponding to the device-tree representation of each of those chips ... and have the platform devices contain the magic attributes. That's a bit more convoluted though.
What's the current trend of the day for that sort of thing ? I'd rather avoid yet-another-chardev-with-ioctl's here ...
Cheers, Ben.
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