Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753113AbbBRA0A (ORCPT ); Tue, 17 Feb 2015 19:26:00 -0500 Received: from gate.crashing.org ([63.228.1.57]:54422 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775AbbBRAZ6 (ORCPT ); Tue, 17 Feb 2015 19:25:58 -0500 Message-ID: <1424219118.21410.111.camel@kernel.crashing.org> Subject: [PATCH 2/2 v3] drivers/core/of: Add symlink to device-tree from devices with an OF node From: Benjamin Herrenschmidt To: Greg Kroah-Hartman Cc: "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arnd Bergmann , Olof Johansson , Grant Likely , Jeremy Kerr , Rob Herring Date: Wed, 18 Feb 2015 11:25:18 +1100 In-Reply-To: References: <1415342031.4925.27.camel@kernel.crashing.org> <1415342117.4925.29.camel@kernel.crashing.org> <1415596626.5769.14.camel@kernel.crashing.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4206 Lines: 117 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 --- 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/