Input: ff-memless - add notion of direction to for rumble effects

This adds simple direction calculation when combining effects. It's useful
to decide motor direction for rumble (vibrator).

Signed-off-by: Jari Vanhala <ext-jari.vanhala@nokia.com>
Acked-by: Anssi Hannula <anssi.hannula@iki.fi>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/ff-memless.c b/drivers/input/ff-memless.c
index 9667a5f..f967008 100644 (file)
--- a/drivers/input/ff-memless.c
+++ b/drivers/input/ff-memless.c
@@ -220,6 +220,22 @@ static int get_compatible_type(struct ff_device *ff, int effect_type)
        return 0;
 }
 
+/*
+ * Only left/right direction should be used (under/over 0x8000) for
+ * forward/reverse motor direction (to keep calculation fast & simple).
+ */
+static u16 ml_calculate_direction(u16 direction, u16 force,
+                                 u16 new_direction, u16 new_force)
+{
+       if (!force)
+               return new_direction;
+       if (!new_force)
+               return direction;
+       return (((u32)(direction >> 1) * force +
+                (new_direction >> 1) * new_force) /
+               (force + new_force)) << 1;
+}
+
 /*
  * Combine two effects and apply gain.
  */
@@ -254,6 +270,19 @@ static void ml_combine_effects(struct ff_effect *effect,
        case FF_RUMBLE:
                strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
                weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
+
+               if (effect->u.rumble.strong_magnitude + strong)
+                       effect->direction = ml_calculate_direction(
+                               effect->direction,
+                               effect->u.rumble.strong_magnitude,
+                               new->direction, strong);
+               else if (effect->u.rumble.weak_magnitude + weak)
+                       effect->direction = ml_calculate_direction(
+                               effect->direction,
+                               effect->u.rumble.weak_magnitude,
+                               new->direction, weak);
+               else
+                       effect->direction = 0;
                effect->u.rumble.strong_magnitude =
                        min(strong + effect->u.rumble.strong_magnitude,
                            0xffffU);
@@ -268,6 +297,13 @@ static void ml_combine_effects(struct ff_effect *effect,
                /* here we also scale it 0x7fff => 0xffff */
                i = i * gain / 0x7fff;
 
+               if (effect->u.rumble.strong_magnitude + i)
+                       effect->direction = ml_calculate_direction(
+                               effect->direction,
+                               effect->u.rumble.strong_magnitude,
+                               new->direction, i);
+               else
+                       effect->direction = 0;
                effect->u.rumble.strong_magnitude =
                        min(i + effect->u.rumble.strong_magnitude, 0xffffU);
                effect->u.rumble.weak_magnitude =