Input: psmouse - expose drift duration for IBM trackpoints

IBM Trackpoints have a feature to compensate for drift by recalibrating
themselves periodically. By default, if for 0.5 seconds there is no change
in position, it's used as the new zero. This duration is too low. Often,
the calibration happens when the trackpoint is in fact being used.

IBM's Trackpoint Engineering Specifications show a configuration register
that allows changing this duration, rstdft1.

Expose it via sysfs among the other settings.

Signed-off-by: Mike Murdoch <main.haarp@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

2 files changed, 9 insertions, 0 deletions

diff --git a/drivers/input/mouse/trackpoint.c b/drivers/input/mouse/trackpoint.c
index 30c8b6998808..354d47ecd66a 100644
--- a/drivers/input/mouse/trackpoint.c
+++ b/drivers/input/mouse/trackpoint.c
@@ -227,6 +227,7 @@ TRACKPOINT_INT_ATTR(thresh, TP_THRESH, TP_DEF_THRESH);
 TRACKPOINT_INT_ATTR(upthresh, TP_UP_THRESH, TP_DEF_UP_THRESH);
 TRACKPOINT_INT_ATTR(ztime, TP_Z_TIME, TP_DEF_Z_TIME);
 TRACKPOINT_INT_ATTR(jenks, TP_JENKS_CURV, TP_DEF_JENKS_CURV);
+TRACKPOINT_INT_ATTR(drift_time, TP_DRIFT_TIME, TP_DEF_DRIFT_TIME);
 
 TRACKPOINT_BIT_ATTR(press_to_select, TP_TOGGLE_PTSON, TP_MASK_PTSON, 0,
                     TP_DEF_PTSON);
@@ -246,6 +247,7 @@ static struct attribute *trackpoint_attrs[] = {
         &psmouse_attr_upthresh.dattr.attr,
         &psmouse_attr_ztime.dattr.attr,
         &psmouse_attr_jenks.dattr.attr,
+        &psmouse_attr_drift_time.dattr.attr,
         &psmouse_attr_press_to_select.dattr.attr,
         &psmouse_attr_skipback.dattr.attr,
         &psmouse_attr_ext_dev.dattr.attr,
@@ -312,6 +314,7 @@ static int trackpoint_sync(struct psmouse *psmouse, bool in_power_on_state)
         TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, upthresh);
         TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, ztime);
         TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, jenks);
+        TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, drift_time);
 
         /* toggles */
         TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, press_to_select);
@@ -332,6 +335,7 @@ static void trackpoint_defaults(struct trackpoint_data *tp)
         TRACKPOINT_SET_POWER_ON_DEFAULT(tp, upthresh);
         TRACKPOINT_SET_POWER_ON_DEFAULT(tp, ztime);
         TRACKPOINT_SET_POWER_ON_DEFAULT(tp, jenks);
+        TRACKPOINT_SET_POWER_ON_DEFAULT(tp, drift_time);
         TRACKPOINT_SET_POWER_ON_DEFAULT(tp, inertia);
 
         /* toggles */
diff --git a/drivers/input/mouse/trackpoint.h b/drivers/input/mouse/trackpoint.h
index ecd0547964a5..5617ed3a7d7a 100644
--- a/drivers/input/mouse/trackpoint.h
+++ b/drivers/input/mouse/trackpoint.h
@@ -70,6 +70,9 @@
 #define TP_UP_THRESH            0x5A    /* Used to generate a 'click' on Z-axis */
 #define TP_Z_TIME               0x5E    /* How sharp of a press */
 #define TP_JENKS_CURV           0x5D    /* Minimum curvature for double click */
+#define TP_DRIFT_TIME           0x5F    /* How long a 'hands off' condition */
+                                        /* must last (x*107ms) for drift */
+                                        /* correction to occur */
 
 /*
  * Toggling Flag bits
@@ -120,6 +123,7 @@
 #define TP_DEF_UP_THRESH        0xFF
 #define TP_DEF_Z_TIME           0x26
 #define TP_DEF_JENKS_CURV       0x87
+#define TP_DEF_DRIFT_TIME       0x05
 
 /* Toggles */
 #define TP_DEF_MB               0x00
@@ -137,6 +141,7 @@ struct trackpoint_data
         unsigned char draghys, mindrag;
         unsigned char thresh, upthresh;
         unsigned char ztime, jenks;
+        unsigned char drift_time;
 
         /* toggles */
         unsigned char press_to_select;