Input: gameport - provide default trigger() and read()

Instead of constantly checking pointer(s) for non-NULL-ness provide
default implementations of trigger() and read() and instantiate them during
pore registration if driver-specific versions were not provided.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/gameport/gameport.c

···
 
 #include <linux/stddef.h>
 #include <linux/module.h>
+#include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/gameport.h>
···
 #include <linux/sched.h>	/* HZ */
 #include <linux/mutex.h>
 #include <linux/timekeeping.h>
-
-/*#include <asm/io.h>*/
 
 MODULE_AUTHOR("Vojtech Pavlik <[e-mail]>");
 MODULE_DESCRIPTION("Generic gameport layer");
···
 }
 EXPORT_SYMBOL(gameport_set_phys);
 
+static void gameport_default_trigger(struct gameport *gameport)
+{
+	outb(0xff, gameport->io);
+}
+
+static unsigned char gameport_default_read(struct gameport *gameport)
+{
+	return inb(gameport->io);
+}
+
 /*
  * Prepare gameport port for registration.
  */
···
 	gameport->dev.release = gameport_release_port;
 	if (gameport->parent)
 		gameport->dev.parent = &gameport->parent->dev;
+
+	if (!gameport->trigger)
+		gameport->trigger = gameport_default_trigger;
+	if (!gameport->read)
+		gameport->read = gameport_default_read;
 
 	INIT_LIST_HEAD(&gameport->node);
 	spin_lock_init(&gameport->timer_lock);

include/linux/gameport.h

···
 #ifndef _GAMEPORT_H
 #define _GAMEPORT_H
 
-#include <asm/io.h>
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
···
 
 static inline void gameport_trigger(struct gameport *gameport)
 {
-	if (gameport->trigger)
-		gameport->trigger(gameport);
-	else
-		outb(0xff, gameport->io);
+	gameport->trigger(gameport);
 }
 
 static inline unsigned char gameport_read(struct gameport *gameport)
 {
-	if (gameport->read)
-		return gameport->read(gameport);
-	else
-		return inb(gameport->io);
+	return gameport->read(gameport);
 }
 
 static inline int gameport_cooked_read(struct gameport *gameport, int *axes, int *buttons)