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authorMark McLoughlin <markmc@redhat.com>2008-12-15 12:58:26 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2009-01-06 10:44:33 -0800
commit0aa0dc41bfd993491c2344870eee7a3b218551fb (patch)
treebf0896c7e0bb9f5b7e6253fc15c8846b6f188d08 /drivers/base
parent7232800ba8aca1c070d43a81cc49991f230b5da1 (diff)
downloadop-kernel-dev-0aa0dc41bfd993491c2344870eee7a3b218551fb.zip
op-kernel-dev-0aa0dc41bfd993491c2344870eee7a3b218551fb.tar.gz
driver core: add root_device_register()
Add support for allocating root device objects which group device objects under /sys/devices directories. Also add a sysfs 'module' symlink which points to the owner of the root device object. This symlink will be used in virtio to allow userspace to determine which virtio bus implementation a given device is associated with. [Includes suggestions from Cornelia Huck] Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/core.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ee555d7..61df508 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1217,6 +1217,97 @@ EXPORT_SYMBOL_GPL(put_device);
EXPORT_SYMBOL_GPL(device_create_file);
EXPORT_SYMBOL_GPL(device_remove_file);
+struct root_device
+{
+ struct device dev;
+ struct module *owner;
+};
+
+#define to_root_device(dev) container_of(dev, struct root_device, dev)
+
+static void root_device_release(struct device *dev)
+{
+ kfree(to_root_device(dev));
+}
+
+/**
+ * __root_device_register - allocate and register a root device
+ * @name: root device name
+ * @owner: owner module of the root device, usually THIS_MODULE
+ *
+ * This function allocates a root device and registers it
+ * using device_register(). In order to free the returned
+ * device, use root_device_unregister().
+ *
+ * Root devices are dummy devices which allow other devices
+ * to be grouped under /sys/devices. Use this function to
+ * allocate a root device and then use it as the parent of
+ * any device which should appear under /sys/devices/{name}
+ *
+ * The /sys/devices/{name} directory will also contain a
+ * 'module' symlink which points to the @owner directory
+ * in sysfs.
+ *
+ * Note: You probably want to use root_device_register().
+ */
+struct device *__root_device_register(const char *name, struct module *owner)
+{
+ struct root_device *root;
+ int err = -ENOMEM;
+
+ root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
+ if (!root)
+ return ERR_PTR(err);
+
+ err = dev_set_name(&root->dev, name);
+ if (err) {
+ kfree(root);
+ return ERR_PTR(err);
+ }
+
+ root->dev.release = root_device_release;
+
+ err = device_register(&root->dev);
+ if (err) {
+ put_device(&root->dev);
+ return ERR_PTR(err);
+ }
+
+#ifdef CONFIG_MODULE /* gotta find a "cleaner" way to do this */
+ if (owner) {
+ struct module_kobject *mk = &owner->mkobj;
+
+ err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
+ if (err) {
+ device_unregister(&root->dev);
+ return ERR_PTR(err);
+ }
+ root->owner = owner;
+ }
+#endif
+
+ return &root->dev;
+}
+EXPORT_SYMBOL_GPL(__root_device_register);
+
+/**
+ * root_device_unregister - unregister and free a root device
+ * @root: device going away.
+ *
+ * This function unregisters and cleans up a device that was created by
+ * root_device_register().
+ */
+void root_device_unregister(struct device *dev)
+{
+ struct root_device *root = to_root_device(dev);
+
+ if (root->owner)
+ sysfs_remove_link(&root->dev.kobj, "module");
+
+ device_unregister(dev);
+}
+EXPORT_SYMBOL_GPL(root_device_unregister);
+
static void device_create_release(struct device *dev)
{
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