From: Frank Rowand <frowand.list@gmail.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: devicetree@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Rob Herring <robherring2@gmail.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [RFC] Add of_path property for all devices with a node
Date: Wed, 12 Nov 2014 20:28:52 -0800 [thread overview]
Message-ID: <54643384.5030309@gmail.com> (raw)
In-Reply-To: <1415342031.4925.27.camel@kernel.crashing.org>
On 11/6/2014 10:33 PM, Benjamin Herrenschmidt wrote:
> Hey folks ! This is not (yet) a formal patch submission but...
>
> So I've been annoyed lately with having a bunch of devices such as i2c
> eeproms (for use by VPDs, server world !) and other bits and pieces that
> I want to be able to identify from userspace, and possibly provide
> additional data about from FW.
>
> Basically, it boils down to correlating the sysfs device with the OF
> tree device node, so that user space can use device-tree info such as
> additional "location" or "label" (or whatever else we can come up with)
> propreties to identify a given device, or get some attributes of use
> about it, etc...
>
> Now, so far, we've done that in some subsystem in a fairly ad-hoc basis
> using "devspec" properties. For example, PCI creates them if it can
> correlate the probed device with a DT node. Some powerpc specific busses
> do that too.
>
> However, i2c doesn't and it would be nice to have something more generic
> since technically any device can have a corresponding device tree node.
>
> So I came up with this patch, it seems to work well for me. I'm adding
> an "of_path" attribute to not conflict with the existing "devspec" one
> just for the sake of this experiment (plus "devspec" sucks). Long run,
> we might want to use of_path and leave a "devspec" symlink to of_path on
> the few busses that currently have devspec (pci and some powerpc
> specific ones).
>
> Comments ?
>
> Cheers,
> Ben.
If I understand correctly, that information is already available in
the file uevent. For example, if I apply your patch, at least
for a simple path, I see the same path name in uevent as in of_path:
$ cd /sys/devices/soc/f9824900.sdhci
$ cat of_path
/soc/sdhci@f9824900
$ grep OF_FULLNAME uevent | cut -d"=" -f2
/soc/sdhci@f9824900
-Frank
prev parent reply other threads:[~2014-11-13 4:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 6:33 [RFC] Add of_path property for all devices with a node Benjamin Herrenschmidt
2014-11-07 6:35 ` Benjamin Herrenschmidt
2014-11-10 5:17 ` Benjamin Herrenschmidt
2014-11-10 14:06 ` Rob Herring
2014-11-10 22:48 ` Benjamin Herrenschmidt
2014-11-13 1:10 ` [PATCH] drivers/core/of: Add symlink to device-tree from devices with an OF node Benjamin Herrenschmidt
2014-11-18 16:37 ` Rob Herring
2014-11-18 23:39 ` Jeremy Kerr
2014-11-18 23:53 ` Jeremy Kerr
2014-11-19 2:35 ` Benjamin Herrenschmidt
2014-11-19 8:38 ` Arnd Bergmann
2014-11-19 14:45 ` Rob Herring
2014-11-19 14:49 ` Arnd Bergmann
2014-11-19 15:39 ` Rob Herring
2014-11-19 16:30 ` Grant Likely
2014-11-19 2:30 ` Benjamin Herrenschmidt
2014-11-27 3:39 ` Greg KH
2014-11-27 6:24 ` Benjamin Herrenschmidt
2014-11-18 15:18 ` [RFC] Add of_path property for all devices with a node Grant Likely
2014-11-19 2:25 ` Benjamin Herrenschmidt
2015-02-18 0:25 ` [PATCH 2/2 v3] drivers/core/of: Add symlink to device-tree from devices with an OF node Benjamin Herrenschmidt
2015-02-18 1:07 ` Rob Herring
2015-02-18 4:57 ` Greg Kroah-Hartman
2015-02-18 9:50 ` Benjamin Herrenschmidt
2015-03-10 14:22 ` Rob Herring
2015-03-10 15:11 ` Greg Kroah-Hartman
2015-02-18 4:57 ` Greg Kroah-Hartman
2014-11-13 4:28 ` Frank Rowand [this message]
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