From 5590f3196b293574a12be58d06d5e1120d8856ec Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 18 Feb 2015 11:25:18 +1100 Subject: [PATCH] drivers/core/of: Add symlink to device-tree from devices with an OF node 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 Signed-off-by: Greg Kroah-Hartman --- 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 000000000000..43f78b88da28 --- /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 e0998b6b6c49..cadf165651d8 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 @@ static int device_add_class_symlinks(struct device *dev) 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;