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    SubjectRe: [PATCH 2/2 v3] drivers/core/of: Add symlink to device-tree from devices with an OF node
    On Wed, Feb 18, 2015 at 11:25:18AM +1100, Benjamin Herrenschmidt wrote:
    > 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.
    >
    > This patch adds an "of_node" symlink to devices that have a non-NULL
    > dev->of_node pointer, the patch is pretty trivial and seems to work just
    > fine for me.
    >
    > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    > ---
    >
    > This addresses Greg's comments. Note that I'm not 100% certain about
    > using device_add_class_symlinks(), I had to put the code before the
    > test for dev->class, maybe we should rename that function to device_add_symlinks()
    > if it grows beyond the class bits ?

    That would probably be a good idea, but we can leave it for now.

    > Also there was nothing that I could find in Documentation/ABI that
    > documented "core" device properties, it's all in
    > Documentation/sysfs-rules.txt, but as suggested by Greg (on IRC) I
    > went for ABI anyway, so I've added a file for "generic" properties
    > and added that one in. I'm happy to change it if you think that's not
    > right, just let me know where you want things.

    It looks good as-is, thanks.

    greg k-h


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