ssb: Make the GPIO API reentrancy safe

This fixes the GPIO API to be reentrancy safe.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/ssb/ssb.h b/include/linux/ssb/ssb.h
index 9d5da8b..d14c036 100644
--- a/include/linux/ssb/ssb.h
+++ b/include/linux/ssb/ssb.h
@@ -283,6 +283,11 @@
 	/* Contents of the SPROM. */
 	struct ssb_sprom sprom;
 
+#ifdef CONFIG_SSB_EMBEDDED
+	/* Lock for GPIO register access. */
+	spinlock_t gpio_lock;
+#endif /* EMBEDDED */
+
 	/* Internal-only stuff follows. Do not touch. */
 	struct list_head list;
 #ifdef CONFIG_SSB_DEBUG