driverfs: Add ability to create and remove files for bus drivers

These behave identically to device attribute files, but with different types. 

We get struct bus_attribute, and a macro, BUS_ATTR for declaring attributes. It takes the same parameters
as DEVICE_ATTR, though the callbacks for bus attributes take a struct bus_type as the first parameter.

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 5dfa05c2dd3a..9707eca4331f 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -85,6 +85,24 @@ extern int bus_for_each_drv(struct bus_type * bus, void * data,
 			    int (*callback)(struct device_driver * drv, void * data));
 
 
+/* driverfs interface for exporting bus attributes */
+
+struct bus_attribute {
+	struct attribute	attr;
+	ssize_t (*show)(struct bus_type *, char * buf, size_t count, loff_t off);
+	ssize_t (*store)(struct bus_type *, const char * buf, size_t count, loff_t off);
+};
+
+#define BUS_ATTR(_name,_str,_mode,_show,_store)	\
+struct bus_attribute bus_attr_##_name = { 		\
+	.attr = {.name	= _str,	.mode	= _mode },	\
+	.show	= _show,				\
+	.store	= _store,				\
+};
+
+extern int bus_create_file(struct bus_type *, struct bus_attribute *);
+extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
+
 struct device_driver {
 	char			* name;
 	struct bus_type		* bus;