Input: hgpk - support GlideSensor and PenTablet modes

Add a "hgpk_mode" sysfs attribute that allows selection between 3 options:
Mouse (the existing option), GlideSensor and PenTablet.

GlideSensor is an enhanced protocol for the regular touchpad mode that
additionally reports pressure and uses absolute coordinates. We suspect
that it may be more reliable than mouse mode in some environments.

PenTablet mode puts the touchpad into resistive mode, you must then use
a stylus as an input. We suspect this is the most reliable way to drive
the touchpad.

The GlideSensor and PenTablet devices expose themselves with the
intention of being combined with the synaptics X11 input driver.

Based on earlier work by Paul Fox.
Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/mouse/hgpk.h

@@ -5,6 +5,9 @@
 #ifndef _HGPK_H
 #define _HGPK_H
 
+#define HGPK_GS		0xff       /* The GlideSensor */
+#define HGPK_PT		0xcf       /* The PenTablet */
+
 enum hgpk_model_t {
 	HGPK_MODEL_PREA = 0x0a,	/* pre-B1s */
 	HGPK_MODEL_A = 0x14,	/* found on B1s, PT disabled in hardware */
@@ -13,12 +16,21 @@ enum hgpk_model_t {
 	HGPK_MODEL_D = 0x50,	/* C1, mass production */
 };
 
+enum hgpk_mode {
+	HGPK_MODE_MOUSE,
+	HGPK_MODE_GLIDESENSOR,
+	HGPK_MODE_PENTABLET,
+	HGPK_MODE_INVALID
+};
+
 struct hgpk_data {
 	struct psmouse *psmouse;
+	enum hgpk_mode mode;
 	bool powered;
 	int count, x_tally, y_tally;	/* hardware workaround stuff */
 	unsigned long recalib_window;
 	struct delayed_work recalib_wq;
+	int abs_x, abs_y;
 };
 
 #define hgpk_dbg(psmouse, format, arg...)		\
@@ -33,9 +45,13 @@ struct hgpk_data {
 	dev_notice(&(psmouse)->ps2dev.serio->dev, format, ## arg)
 
 #ifdef CONFIG_MOUSE_PS2_OLPC
+void hgpk_module_init(void);
 int hgpk_detect(struct psmouse *psmouse, bool set_properties);
 int hgpk_init(struct psmouse *psmouse);
 #else
+static inline void hgpk_module_init(void)
+{
+}
 static inline int hgpk_detect(struct psmouse *psmouse, bool set_properties)
 {
 	return -ENODEV;

drivers/input/mouse/psmouse-base.c

@@ -1711,6 +1711,7 @@ static int __init psmouse_init(void)
 
 	lifebook_module_init();
 	synaptics_module_init();
+	hgpk_module_init();
 
 	kpsmoused_wq = create_singlethread_workqueue("kpsmoused");
 	if (!kpsmoused_wq) {