clocksource: make CLOCKSOURCE_OF_DECLARE type safe

This ensures that a function pointer passed into CLOCKSOURCE_OF_DECLARE
takes the same arguments that we use for calling that function later.

Also fix the extraneous semicolon at end of the CLOCKSOURCE_OF_DECLARE
definition.

Signed-off-by: Arnd Bergmann <[e-mail]>
Acked-by: Rob Herring <[e-mail]>

drivers/clocksource/clksrc-of.c

···
 
 #include <linux/init.h>
 #include <linux/of.h>
+#include <linux/clocksource.h>
 
 extern struct of_device_id __clksrc_of_table[];
 
···
 {
 	struct device_node *np;
 	const struct of_device_id *match;
-	void (*init_func)(struct device_node *);
+	clocksource_of_init_fn init_func;
 
 	for_each_matching_node_and_match(np, __clksrc_of_table, &match) {
 		init_func = match->data;

drivers/clocksource/vt8500_timer.c

···
 					4, 0xf0000000);
 }
 
-CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init)
+CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);

include/linux/clocksource.h

···
 
 extern int clocksource_i8253_init(void);
 
+struct device_node;
+typedef void(*clocksource_of_init_fn)(struct device_node *);
 #ifdef CONFIG_CLKSRC_OF
 extern void clocksource_of_init(void);
 
 #define CLOCKSOURCE_OF_DECLARE(name, compat, fn)			\
 	static const struct of_device_id __clksrc_of_table_##name	\
 		__used __section(__clksrc_of_table)			\
-		 = { .compatible = compat, .data = fn };
+		 = { .compatible = compat,				\
+		     .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn }
 #else
 static inline void clocksource_of_init(void) {}
-#define CLOCKSOURCE_OF_DECLARE(name, compat, fn)
+#define CLOCKSOURCE_OF_DECLARE(name, compat, fn)			\
+	static const struct of_device_id __clksrc_of_table_##name	\
+		__attribute__((unused))					\
+		 = { .compatible = compat,				\
+		     .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn }
 #endif
 
 #endif /* _LINUX_CLOCKSOURCE_H */