Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753364AbbBRBHi (ORCPT ); Tue, 17 Feb 2015 20:07:38 -0500 Received: from mail-wi0-f181.google.com ([209.85.212.181]:59955 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751608AbbBRBHg (ORCPT ); Tue, 17 Feb 2015 20:07:36 -0500 MIME-Version: 1.0 In-Reply-To: <1424219118.21410.111.camel@kernel.crashing.org> References: <1415342031.4925.27.camel@kernel.crashing.org> <1415342117.4925.29.camel@kernel.crashing.org> <1415596626.5769.14.camel@kernel.crashing.org> <1424219118.21410.111.camel@kernel.crashing.org> From: Rob Herring Date: Tue, 17 Feb 2015 19:07:14 -0600 Message-ID: Subject: Re: [PATCH 2/2 v3] drivers/core/of: Add symlink to device-tree from devices with an OF node To: Benjamin Herrenschmidt Cc: Greg Kroah-Hartman , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arnd Bergmann , Olof Johansson , Grant Likely , Jeremy Kerr Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4860 Lines: 122 On Tue, Feb 17, 2015 at 6:25 PM, 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 Acked-by: Rob Herring > --- > > 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 ? > > 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. > > I'm not resending patch 1/2, it should still be fine. Let me know if > you want a new copy. > > Documentation/ABI/stable/sysfs-devices | 10 ++++++++++ > drivers/base/core.c | 16 ++++++++++++++-- > 2 files changed, 24 insertions(+), 2 deletions(-) > create mode 100644 Documentation/ABI/stable/sysfs-devices > > diff --git a/Documentation/ABI/stable/sysfs-devices b/Documentation/ABI/stable/sysfs-devices > new file mode 100644 > index 0000000..43f78b88d > --- /dev/null > +++ b/Documentation/ABI/stable/sysfs-devices > @@ -0,0 +1,10 @@ > +# Note: This documents additional properties of any device beyond what > +# is documented in Documentation/sysfs-rules.txt > + > +What: /sys/devices/*/of_path > +Date: February 2015 > +Contact: Device Tree mailing list > +Description: > + Any device associated with a device-tree node will have > + an of_path symlink pointing to the corresponding device > + node in /sys/firmware/devicetree/ > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 97e2baf..2549805 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -805,8 +805,16 @@ static void cleanup_device_parent(struct device *dev) > > static int device_add_class_symlinks(struct device *dev) > { > + struct device_node *of_node = dev_of_node(dev); > int error; > > + if (of_node) { > + error = sysfs_create_link(&dev->kobj, &of_node->kobj,"of_node"); > + if (error) > + dev_warn(dev, "Error %d creating of_node link\n",error); > + /* An error here doesn't warrant bringing down the device */ > + } > + > if (!dev->class) > return 0; > > @@ -814,7 +822,7 @@ static int device_add_class_symlinks(struct device *dev) > &dev->class->p->subsys.kobj, > "subsystem"); > if (error) > - goto out; > + goto out_devnode; > > if (dev->parent && device_is_not_partition(dev)) { > error = sysfs_create_link(&dev->kobj, &dev->parent->kobj, > @@ -842,12 +850,16 @@ out_device: > > out_subsys: > sysfs_remove_link(&dev->kobj, "subsystem"); > -out: > +out_devnode: > + sysfs_remove_link(&dev->kobj, "of_node"); > return error; > } > > static void device_remove_class_symlinks(struct device *dev) > { > + if (dev_of_node(dev)) > + sysfs_remove_link(&dev->kobj, "of_node"); > + > if (!dev->class) > return; > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/