HID: wiimote: lock DRM mode during debugfs overwrite

If we write a DRM mode via debugfs, we shouldn't allow normal operations
to overwrite this DRM mode. This is important if we want to debug
3rd-party devices and we want to see what data is sent on each mode.

If we write NULL/0 as DRM, the lock is removed again so the best matching
DRM is chosen by wiimote core.

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

3 files changed, 7 insertions, 1 deletions

diff --git a/drivers/hid/hid-wiimote-core.c b/drivers/hid/hid-wiimote-core.c
index f6c4773fac56..13963b4c8801 100644
--- a/drivers/hid/hid-wiimote-core.c
+++ b/drivers/hid/hid-wiimote-core.c
@@ -242,7 +242,9 @@ void wiiproto_req_drm(struct wiimote_data *wdata, __u8 drm)
 {
         __u8 cmd[3];
 
-        if (drm == WIIPROTO_REQ_NULL)
+        if (wdata->state.flags & WIIPROTO_FLAG_DRM_LOCKED)
+                drm = wdata->state.drm;
+        else if (drm == WIIPROTO_REQ_NULL)
                 drm = select_drm(wdata);
 
         cmd[0] = WIIPROTO_REQ_DRM;
diff --git a/drivers/hid/hid-wiimote-debug.c b/drivers/hid/hid-wiimote-debug.c
index 0c0deaa23774..6e76a2c3b00a 100644
--- a/drivers/hid/hid-wiimote-debug.c
+++ b/drivers/hid/hid-wiimote-debug.c
@@ -154,7 +154,10 @@ static ssize_t wiidebug_drm_write(struct file *f, const char __user *u,
                 i = simple_strtoul(buf, NULL, 10);
 
         spin_lock_irqsave(&dbg->wdata->state.lock, flags);
+        dbg->wdata->state.flags &= ~WIIPROTO_FLAG_DRM_LOCKED;
         wiiproto_req_drm(dbg->wdata, (__u8) i);
+        if (i != WIIPROTO_REQ_NULL)
+                dbg->wdata->state.flags |= WIIPROTO_FLAG_DRM_LOCKED;
         spin_unlock_irqrestore(&dbg->wdata->state.lock, flags);
 
         return len;
diff --git a/drivers/hid/hid-wiimote.h b/drivers/hid/hid-wiimote.h
index 3a8bdb94152a..9f857c1cd84a 100644
--- a/drivers/hid/hid-wiimote.h
+++ b/drivers/hid/hid-wiimote.h
@@ -43,6 +43,7 @@
 #define WIIPROTO_FLAG_MP_USED           0x1000
 #define WIIPROTO_FLAG_MP_ACTIVE         0x2000
 #define WIIPROTO_FLAG_EXITING           0x4000
+#define WIIPROTO_FLAG_DRM_LOCKED        0x8000
 
 #define WIIPROTO_FLAGS_LEDS (WIIPROTO_FLAG_LED1 | WIIPROTO_FLAG_LED2 | \
                                         WIIPROTO_FLAG_LED3 | WIIPROTO_FLAG_LED4)