Input: joystick - use ktime for measuring timing

[sfrench/cifs-2.6.git] / drivers / input / gameport / gameport.c

diff --git a/drivers/input/gameport/gameport.c b/drivers/input/gameport/gameport.c
index 24c41ba7d4e01dcf852050d3f1d8ef27b5f0a22f..e29c04e2aff4ea1ae4e570be4fa677cb9e014fb3 100644 (file)
--- a/drivers/input/gameport/gameport.c
+++ b/drivers/input/gameport/gameport.c
@@ -23,6 +23,7 @@
 #include <linux/workqueue.h>
 #include <linux/sched.h>       /* HZ */
 #include <linux/mutex.h>
+#include <linux/timekeeping.h>
 
 /*#include <asm/io.h>*/
 
@@ -30,6 +31,10 @@ MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 MODULE_DESCRIPTION("Generic gameport layer");
 MODULE_LICENSE("GPL");
 
+static bool use_ktime = true;
+module_param(use_ktime, bool, 0400);
+MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
+
 /*
  * gameport_mutex protects entire gameport subsystem and is taken
  * every time gameport port or driver registrered or unregistered.
@@ -75,6 +80,38 @@ static unsigned int get_time_pit(void)
  */
 
 static int gameport_measure_speed(struct gameport *gameport)
+{
+       unsigned int i, t, tx;
+       u64 t1, t2, t3;
+       unsigned long flags;
+
+       if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
+               return 0;
+
+       tx = ~0;
+
+       for (i = 0; i < 50; i++) {
+               local_irq_save(flags);
+               t1 = ktime_get_ns();
+               for (t = 0; t < 50; t++)
+                       gameport_read(gameport);
+               t2 = ktime_get_ns();
+               t3 = ktime_get_ns();
+               local_irq_restore(flags);
+               udelay(i * 10);
+               t = (t2 - t1) - (t3 - t2);
+               if (t < tx)
+                       tx = t;
+       }
+
+       gameport_close(gameport);
+       t = 1000000 * 50;
+       if (tx)
+               t /= tx;
+       return t;
+}
+
+static int old_gameport_measure_speed(struct gameport *gameport)
 {
 #if defined(__i386__)
 
@@ -521,7 +558,9 @@ static void gameport_add_port(struct gameport *gameport)
        if (gameport->parent)
                gameport->parent->child = gameport;
 
-       gameport->speed = gameport_measure_speed(gameport);
+       gameport->speed = use_ktime ?
+               gameport_measure_speed(gameport) :
+               old_gameport_measure_speed(gameport);
 
        list_add_tail(&gameport->node, &gameport_list);