HID: wiimote: Add extension support stub

The wiimote supports several extensions. This adds a separate source file which
handles all extensions and can be disabled at compile-time.

The driver reacts on "plug"-events on the extension port and starts a worker
which initializes or deinitializes the extensions.

Currently, the initialization logic is not fully understood and we can only
detect and enable all extensions when all extensions are deactivated. Therefore,
we need to disable all extensions, then detect and activate them again to react
on "plug"-events.
However, deactivating extensions will generate a new "plug"-event and we will
never leave that loop. Hence, we only support extensions if they are plugged
before the wiimote is connected (or before the ext-input device is opened). In
the future we may support full extension hotplug support, but
reverse-engineering this may take a while.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/hid/hid-wiimote.h b/drivers/hid/hid-wiimote.h
index 865740d3a3fe..abbfab8f60b7 100644
--- a/drivers/hid/hid-wiimote.h
+++ b/drivers/hid/hid-wiimote.h
@@ -73,6 +73,7 @@ struct wiimote_data {
         struct input_dev *accel;
         struct input_dev *ir;
         struct power_supply battery;
+        struct wiimote_ext *ext;
 
         spinlock_t qlock;
         __u8 head;
@@ -118,6 +119,22 @@ extern int wiimote_cmd_write(struct wiimote_data *wdata, __u32 offset,
 extern ssize_t wiimote_cmd_read(struct wiimote_data *wdata, __u32 offset,
                                                         __u8 *rmem, __u8 size);
 
+#ifdef CONFIG_HID_WIIMOTE_EXT
+
+extern int wiiext_init(struct wiimote_data *wdata);
+extern void wiiext_deinit(struct wiimote_data *wdata);
+extern void wiiext_event(struct wiimote_data *wdata, bool plugged);
+extern bool wiiext_active(struct wiimote_data *wdata);
+
+#else
+
+static inline int wiiext_init(void *u) { return 0; }
+static inline void wiiext_deinit(void *u) { }
+static inline void wiiext_event(void *u, bool p) { }
+static inline bool wiiext_active(void *u) { return false; }
+
+#endif
+
 /* requires the state.lock spinlock to be held */
 static inline bool wiimote_cmd_pending(struct wiimote_data *wdata, int cmd,
                                                                 __u32 opt)