Driver Core: add nodename callbacks

This adds the nodename callback for struct class, struct device_type and
struct device, to allow drivers to send userspace hints on the device
name and subdirectory that should be used for it.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 50 insertions, 1 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4d59975c24a8..7ecb1938e590 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -162,10 +162,18 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj,
         struct device *dev = to_dev(kobj);
         int retval = 0;
 
-        /* add the major/minor if present */
+        /* add device node properties if present */
         if (MAJOR(dev->devt)) {
+                const char *tmp;
+                const char *name;
+
                 add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
                 add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
+                name = device_get_nodename(dev, &tmp);
+                if (name) {
+                        add_uevent_var(env, "DEVNAME=%s", name);
+                        kfree(tmp);
+                }
         }
 
         if (dev->type && dev->type->name)
@@ -1129,6 +1137,47 @@ static struct device *next_device(struct klist_iter *i)
 }
 
 /**
+ * device_get_nodename - path of device node file
+ * @dev: device
+ * @tmp: possibly allocated string
+ *
+ * Return the relative path of a possible device node.
+ * Non-default names may need to allocate a memory to compose
+ * a name. This memory is returned in tmp and needs to be
+ * freed by the caller.
+ */
+const char *device_get_nodename(struct device *dev, const char **tmp)
+{
+        char *s;
+
+        *tmp = NULL;
+
+        /* the device type may provide a specific name */
+        if (dev->type && dev->type->nodename)
+                *tmp = dev->type->nodename(dev);
+        if (*tmp)
+                return *tmp;
+
+        /* the class may provide a specific name */
+        if (dev->class && dev->class->nodename)
+                *tmp = dev->class->nodename(dev);
+        if (*tmp)
+                return *tmp;
+
+        /* return name without allocation, tmp == NULL */
+        if (strchr(dev_name(dev), '!') == NULL)
+                return dev_name(dev);
+
+        /* replace '!' in the name with '/' */
+        *tmp = kstrdup(dev_name(dev), GFP_KERNEL);
+        if (!*tmp)
+                return NULL;
+        while ((s = strchr(*tmp, '!')))
+                s[0] = '/';
+        return *tmp;
+}
+
+/**
  * device_for_each_child - device child iterator.
  * @parent: parent struct device.
  * @data: data for the callback.