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/ZGvoqP5PAAsJuky4@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/gameport/gameport.c

@@ -11,6 +11,7 @@
 
 #include <linux/stddef.h>
 #include <linux/module.h>
+#include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/gameport.h>
@@ -21,8 +22,6 @@
 #include <linux/mutex.h>
 #include <linux/timekeeping.h>
 
-/*#include <asm/io.h>*/
-
 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 MODULE_DESCRIPTION("Generic gameport layer");
 MODULE_LICENSE("GPL");
@@ -518,6 +517,16 @@ void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
 }
 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.
  */
@@ -536,6 +545,11 @@ static void gameport_init_port(struct gameport *gameport)
 	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);
 	timer_setup(&gameport->poll_timer, gameport_run_poll_handler, 0);

include/linux/gameport.h

@@ -5,7 +5,6 @@
 #ifndef _GAMEPORT_H
 #define _GAMEPORT_H
 
-#include <asm/io.h>
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
@@ -165,18 +164,12 @@ void gameport_unregister_driver(struct gameport_driver *drv);
 
 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)