It looks at least odd to apply spin_unlock to a mutex.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@def@
declarer DEFINE_MUTEX;
identifier m;
@@

DEFINE_MUTEX(m);

@@
identifier def.m;
@@

(
- spin_lock(&m)
+ mutex_lock(&m)
|
- spin_unlock(&m)
+ mutex_unlock(&m)
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>

arch/cris/arch-v10/drivers/pcf8563.c

@@ -233,7 +233,7 @@ int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
 
 		if (copy_to_user((struct rtc_time *) arg, &tm,
 				 sizeof tm)) {
-			spin_unlock(&rtc_lock);
+			mutex_unlock(&rtc_lock);
 			return -EFAULT;
 		}
 

arch/cris/arch-v32/drivers/pcf8563.c

@@ -229,7 +229,7 @@ int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
 
 		if (copy_to_user((struct rtc_time *) arg, &tm,
 				 sizeof tm)) {
-			spin_unlock(&rtc_lock);
+			mutex_unlock(&rtc_lock);
 			return -EFAULT;
 		}