linux-kernel - sysfs for my chips

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 10 Oct 2013 15:19:48 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	Tejun Heo <tj@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: sysfs for my chips

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.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/