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authorJean Delvare <khali@linux-fr.org>2009-08-04 12:55:34 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-15 09:50:48 -0700
commit4622709445705c1e423d2addcfd8ccae052fe0ba (patch)
treec9032374e8f99a5bb9b8b8e012e0a6de4c9c3846
parentccb86a6907c9ba7b5be5f521362fc308e80bed34 (diff)
downloadop-kernel-dev-4622709445705c1e423d2addcfd8ccae052fe0ba.zip
op-kernel-dev-4622709445705c1e423d2addcfd8ccae052fe0ba.tar.gz
Driver core: Add support for compatibility classes
When turning class devices into bus devices, we may need to temporarily add links in sysfs so that user-space applications are not confused. This is done by adding the following API: * Functions to register and unregister compatibility classes. These appear in sysfs at the same location as regular classes, but instead of class devices, they contain links to bus devices. * Functions to create and delete such links. Additionally, the caller can optionally pass a target device to which a "device" link should point (typically that would be the device's parent), to fully emulate the original class device. The i2c subsystem will be the first user of this API, as i2c adapters are being converted from class devices to bus devices. Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
-rw-r--r--drivers/base/class.c87
-rw-r--r--include/linux/device.h8
2 files changed, 95 insertions, 0 deletions
diff --git a/drivers/base/class.c b/drivers/base/class.c
index eb85e43..161746d 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -488,6 +488,93 @@ void class_interface_unregister(struct class_interface *class_intf)
class_put(parent);
}
+struct class_compat {
+ struct kobject *kobj;
+};
+
+/**
+ * class_compat_register - register a compatibility class
+ * @name: the name of the class
+ *
+ * Compatibility class are meant as a temporary user-space compatibility
+ * workaround when converting a family of class devices to a bus devices.
+ */
+struct class_compat *class_compat_register(const char *name)
+{
+ struct class_compat *cls;
+
+ cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
+ if (!cls)
+ return NULL;
+ cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
+ if (!cls->kobj) {
+ kfree(cls);
+ return NULL;
+ }
+ return cls;
+}
+EXPORT_SYMBOL_GPL(class_compat_register);
+
+/**
+ * class_compat_unregister - unregister a compatibility class
+ * @cls: the class to unregister
+ */
+void class_compat_unregister(struct class_compat *cls)
+{
+ kobject_put(cls->kobj);
+ kfree(cls);
+}
+EXPORT_SYMBOL_GPL(class_compat_unregister);
+
+/**
+ * class_compat_create_link - create a compatibility class device link to
+ * a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link should be created
+ */
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link)
+{
+ int error;
+
+ error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
+ if (error)
+ return error;
+
+ /*
+ * Optionally add a "device" link (typically to the parent), as a
+ * class device would have one and we want to provide as much
+ * backwards compatibility as possible.
+ */
+ if (device_link) {
+ error = sysfs_create_link(&dev->kobj, &device_link->kobj,
+ "device");
+ if (error)
+ sysfs_remove_link(cls->kobj, dev_name(dev));
+ }
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(class_compat_create_link);
+
+/**
+ * class_compat_remove_link - remove a compatibility class device link to
+ * a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link was previously
+ * created
+ */
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link)
+{
+ if (device_link)
+ sysfs_remove_link(&dev->kobj, "device");
+ sysfs_remove_link(cls->kobj, dev_name(dev));
+}
+EXPORT_SYMBOL_GPL(class_compat_remove_link);
+
int __init classes_init(void)
{
class_kset = kset_create_and_add("class", NULL, NULL);
diff --git a/include/linux/device.h b/include/linux/device.h
index e19e40a..62ff53a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -225,6 +225,14 @@ extern void class_unregister(struct class *class);
__class_register(class, &__key); \
})
+struct class_compat;
+struct class_compat *class_compat_register(const char *name);
+void class_compat_unregister(struct class_compat *cls);
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link);
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link);
+
extern void class_dev_iter_init(struct class_dev_iter *iter,
struct class *class,
struct device *start,
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