1 files changed, 37 insertions, 3 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index b30527db3ac0..182192892d45 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -106,7 +106,7 @@ extern int bus_unregister_notifier(struct bus_type *bus,
 
 /* All 4 notifers below get called with the target struct device *
  * as an argument. Note that those functions are likely to be called
- * with the device semaphore held in the core, so be careful.
+ * with the device lock held in the core, so be careful.
  */
 #define BUS_NOTIFY_ADD_DEVICE           0x00000001 /* device added */
 #define BUS_NOTIFY_DEL_DEVICE           0x00000002 /* device removed */
@@ -251,8 +251,10 @@ extern struct device *class_find_device(struct class *class,
 
 struct class_attribute {
         struct attribute attr;
-        ssize_t (*show)(struct class *class, char *buf);
-        ssize_t (*store)(struct class *class, const char *buf, size_t count);
+        ssize_t (*show)(struct class *class, struct class_attribute *attr,
+                        char *buf);
+        ssize_t (*store)(struct class *class, struct class_attribute *attr,
+                        const char *buf, size_t count);
 };
 
 #define CLASS_ATTR(_name, _mode, _show, _store)                 \
@@ -263,6 +265,23 @@ extern int __must_check class_create_file(struct class *class,
 extern void class_remove_file(struct class *class,
                               const struct class_attribute *attr);
 
+/* Simple class attribute that is just a static string */
+
+struct class_attribute_string {
+        struct class_attribute attr;
+        char *str;
+};
+
+/* Currently read-only only */
+#define _CLASS_ATTR_STRING(_name, _mode, _str) \
+        { __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
+#define CLASS_ATTR_STRING(_name, _mode, _str) \
+        struct class_attribute_string class_attr_##_name = \
+                _CLASS_ATTR_STRING(_name, _mode, _str)
+
+extern ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
+                        char *buf);
+
 struct class_interface {
         struct list_head        node;
         struct class            *class;
@@ -489,6 +508,21 @@ static inline bool device_async_suspend_enabled(struct device *dev)
         return !!dev->power.async_suspend;
 }
 
+static inline void device_lock(struct device *dev)
+{
+        down(&dev->sem);
+}
+
+static inline int device_trylock(struct device *dev)
+{
+        return down_trylock(&dev->sem);
+}
+
+static inline void device_unlock(struct device *dev)
+{
+        up(&dev->sem);
+}
+
 void driver_init(void);
 
 /*