MODULE_PARM_DESC(post_interrupt_delay,
        "delay (ms) before recal after recal interrupt detected");
 
+static char hgpk_mode_name[16];
+module_param_string(hgpk_mode, hgpk_mode_name, sizeof(hgpk_mode_name), 0644);
+MODULE_PARM_DESC(hgpk_mode,
+       "default hgpk mode: mouse, glidesensor or pentablet");
+
+static int hgpk_default_mode = HGPK_MODE_MOUSE;
+
+static const char * const hgpk_mode_names[] = {
+       [HGPK_MODE_MOUSE] = "Mouse",
+       [HGPK_MODE_GLIDESENSOR] = "GlideSensor",
+       [HGPK_MODE_PENTABLET] = "PenTablet",
+};
+
+static int hgpk_mode_from_name(const char *buf, int len)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(hgpk_mode_names); i++) {
+               const char *name = hgpk_mode_names[i];
+               if (strlen(name) == len && !strncasecmp(name, buf, len))
+                       return i;
+       }
+
+       return HGPK_MODE_INVALID;
+}
+
 /*
  * When the touchpad gets ultra-sensitive, one can keep their finger 1/2"
  * above the pad and still have it send packets.  This causes a jump cursor
  * swr/swl are the left/right buttons.
  * x-neg/y-neg are the x and y delta negative bits
  * x-over/y-over are the x and y overflow bits
+ *
+ * ---
+ *
+ * HGPK Advanced Mode - single-mode format
+ *
+ * byte 0(PT):  1    1    0    0    1    1     1     1
+ * byte 0(GS):  1    1    1    1    1    1     1     1
+ * byte 1:      0   x6   x5   x4   x3   x2    x1    x0
+ * byte 2(PT):  0    0   x9   x8   x7    ? pt-dsw    0
+ * byte 2(GS):  0  x10   x9   x8   x7    ? gs-dsw pt-dsw
+ * byte 3:      0   y9   y8   y7    1    0   swr   swl
+ * byte 4:      0   y6   y5   y4   y3   y2    y1    y0
+ * byte 5:      0   z6   z5   z4   z3   z2    z1    z0
+ *
+ * ?'s are not defined in the protocol spec, may vary between models.
+ *
+ * swr/swl are the left/right buttons.
+ *
+ * pt-dsw/gs-dsw indicate that the pt/gs sensor is detecting a
+ * pen/finger
  */
-static int hgpk_validate_byte(unsigned char *packet)
+static bool hgpk_is_byte_valid(struct psmouse *psmouse, unsigned char *packet)
 {
-       return (packet[0] & 0x0C) != 0x08;
+       struct hgpk_data *priv = psmouse->private;
+       int pktcnt = psmouse->pktcnt;
+       bool valid;
+
+       switch (priv->mode) {
+       case HGPK_MODE_MOUSE:
+               valid = (packet[0] & 0x0C) == 0x08;
+               break;
+
+       case HGPK_MODE_GLIDESENSOR:
+               valid = pktcnt == 1 ?
+                       packet[0] == HGPK_GS : !(packet[pktcnt - 1] & 0x80);
+               break;
+
+       case HGPK_MODE_PENTABLET:
+               valid = pktcnt == 1 ?
+                       packet[0] == HGPK_PT : !(packet[pktcnt - 1] & 0x80);
+               break;
+
+       default:
+               valid = false;
+               break;
+       }
+
+       if (!valid)
+               hgpk_dbg(psmouse,
+                        "bad data, mode %d (%d) %02x %02x %02x %02x %02x %02x\n",
+                        priv->mode, pktcnt,
+                        psmouse->packet[0], psmouse->packet[1],
+                        psmouse->packet[2], psmouse->packet[3],
+                        psmouse->packet[4], psmouse->packet[5]);
+
+       return valid;
 }
 
-static void hgpk_process_packet(struct psmouse *psmouse)
+static void hgpk_process_advanced_packet(struct psmouse *psmouse)
 {
-       struct input_dev *dev = psmouse->dev;
+       struct hgpk_data *priv = psmouse->private;
+       struct input_dev *idev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
-       int x, y, left, right;
+       int down = !!(packet[2] & 2);
+       int left = !!(packet[3] & 1);
+       int right = !!(packet[3] & 2);
+       int x = packet[1] | ((packet[2] & 0x78) << 4);
+       int y = packet[4] | ((packet[3] & 0x70) << 3);
+
+       if (priv->mode == HGPK_MODE_GLIDESENSOR) {
+               int pt_down = !!(packet[2] & 1);
+               int finger_down = !!(packet[2] & 2);
+               int z = packet[5];
+
+               input_report_abs(idev, ABS_PRESSURE, z);
+               if (tpdebug)
+                       hgpk_dbg(psmouse, "pd=%d fd=%d z=%d",
+                                pt_down, finger_down, z);
+       } else {
+               /*
+                * PenTablet mode does not report pressure, so we don't
+                * report it here
+                */
+               if (tpdebug)
+                       hgpk_dbg(psmouse, "pd=%d ", down);
+       }
 
-       left = packet[0] & 1;
-       right = (packet[0] >> 1) & 1;
+       if (tpdebug)
+               hgpk_dbg(psmouse, "l=%d r=%d x=%d y=%d\n", left, right, x, y);
 
-       x = packet[1] - ((packet[0] << 4) & 0x100);
-       y = ((packet[0] << 3) & 0x100) - packet[2];
+       input_report_key(idev, BTN_TOUCH, down);
+       input_report_key(idev, BTN_LEFT, left);
+       input_report_key(idev, BTN_RIGHT, right);
+
+       /*
+        * If this packet says that the finger was removed, reset our position
+        * tracking so that we don't erroneously detect a jump on next press.
+        */
+       if (!down)
+               priv->abs_x = priv->abs_y = -1;
+
+       /*
+        * Report position if finger/pen is down, but weed out duplicate
+        * packets (we get quite a few in this mode, and they mess up our
+        * jump detection.
+        */
+       if (down && (x != priv->abs_x || y != priv->abs_y)) {
+
+               /* Don't apply hacks in PT mode, it seems reliable */
+               if (priv->mode != HGPK_MODE_PENTABLET && priv->abs_x != -1) {
+                       hgpk_jumpy_hack(psmouse,
+                                       priv->abs_x - x, priv->abs_y - y);
+                       hgpk_spewing_hack(psmouse, left, right,
+                                         priv->abs_x - x, priv->abs_y - y);
+               }
+
+               input_report_abs(idev, ABS_X, x);
+               input_report_abs(idev, ABS_Y, y);
+               priv->abs_x = x;
+               priv->abs_y = y;
+       }
+
+       input_sync(idev);
+}
+
+static void hgpk_process_simple_packet(struct psmouse *psmouse)
+{
+       struct input_dev *dev = psmouse->dev;
+       unsigned char *packet = psmouse->packet;
+       int left = packet[0] & 1;
+       int right = (packet[0] >> 1) & 1;
+       int x = packet[1] - ((packet[0] << 4) & 0x100);
+       int y = ((packet[0] << 3) & 0x100) - packet[2];
 
        hgpk_jumpy_hack(psmouse, x, y);
        hgpk_spewing_hack(psmouse, left, right, x, y);
 {
        struct hgpk_data *priv = psmouse->private;
 
-       if (hgpk_validate_byte(psmouse->packet)) {
-               hgpk_dbg(psmouse, "%s: (%d) %02x %02x %02x\n",
-                               __func__, psmouse->pktcnt, psmouse->packet[0],
-                               psmouse->packet[1], psmouse->packet[2]);
+       if (!hgpk_is_byte_valid(psmouse, psmouse->packet))
                return PSMOUSE_BAD_DATA;
-       }
 
        if (psmouse->pktcnt >= psmouse->pktsize) {
-               hgpk_process_packet(psmouse);
+               if (priv->mode == HGPK_MODE_MOUSE)
+                       hgpk_process_simple_packet(psmouse);
+               else
+                       hgpk_process_advanced_packet(psmouse);
                return PSMOUSE_FULL_PACKET;
        }
 
        return PSMOUSE_GOOD_DATA;
 }
 
+static int hgpk_select_mode(struct psmouse *psmouse)
+{
+       struct ps2dev *ps2dev = &psmouse->ps2dev;
+       struct hgpk_data *priv = psmouse->private;
+       int i;
+       int cmd;
+
+       /*
+        * 4 disables to enable advanced mode
+        * then 3 0xf2 bytes as the preamble for GS/PT selection
+        */
+       const int advanced_init[] = {
+               PSMOUSE_CMD_DISABLE, PSMOUSE_CMD_DISABLE,
+               PSMOUSE_CMD_DISABLE, PSMOUSE_CMD_DISABLE,
+               0xf2, 0xf2, 0xf2,
+       };
+
+       switch (priv->mode) {
+       case HGPK_MODE_MOUSE:
+               psmouse->pktsize = 3;
+               break;
+
+       case HGPK_MODE_GLIDESENSOR:
+       case HGPK_MODE_PENTABLET:
+               psmouse->pktsize = 6;
+
+               /* Switch to 'Advanced mode.', four disables in a row. */
+               for (i = 0; i < ARRAY_SIZE(advanced_init); i++)
+                       if (ps2_command(ps2dev, NULL, advanced_init[i]))
+                               return -EIO;
+
+               /* select between GlideSensor (mouse) or PenTablet */
+               cmd = priv->mode == HGPK_MODE_GLIDESENSOR ?
+                       PSMOUSE_CMD_SETSCALE11 : PSMOUSE_CMD_SETSCALE21;
+
+               if (ps2_command(ps2dev, NULL, cmd))
+                       return -EIO;
+               break;
+
+       default:
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static void hgpk_setup_input_device(struct input_dev *input,
+                                   struct input_dev *old_input,
+                                   enum hgpk_mode mode)
+{
+       if (old_input) {
+               input->name = old_input->name;
+               input->phys = old_input->phys;
+               input->id = old_input->id;
+               input->dev.parent = old_input->dev.parent;
+       }
+
+       memset(input->evbit, 0, sizeof(input->evbit));
+       memset(input->relbit, 0, sizeof(input->relbit));
+       memset(input->keybit, 0, sizeof(input->keybit));
+
+       /* All modes report left and right buttons */
+       __set_bit(EV_KEY, input->evbit);
+       __set_bit(BTN_LEFT, input->keybit);
+       __set_bit(BTN_RIGHT, input->keybit);
+
+       switch (mode) {
+       case HGPK_MODE_MOUSE:
+               __set_bit(EV_REL, input->evbit);
+               __set_bit(REL_X, input->relbit);
+               __set_bit(REL_Y, input->relbit);
+               break;
+
+       case HGPK_MODE_GLIDESENSOR:
+               __set_bit(BTN_TOUCH, input->keybit);
+               __set_bit(BTN_TOOL_FINGER, input->keybit);
+
+               __set_bit(EV_ABS, input->evbit);
+
+               /* GlideSensor has pressure sensor, PenTablet does not */
+               input_set_abs_params(input, ABS_PRESSURE, 0, 15, 0, 0);
+
+               /* From device specs */
+               input_set_abs_params(input, ABS_X, 0, 399, 0, 0);
+               input_set_abs_params(input, ABS_Y, 0, 290, 0, 0);
+
+               /* Calculated by hand based on usable size (52mm x 38mm) */
+               input_abs_set_res(input, ABS_X, 8);
+               input_abs_set_res(input, ABS_Y, 8);
+               break;
+
+       case HGPK_MODE_PENTABLET:
+               __set_bit(BTN_TOUCH, input->keybit);
+               __set_bit(BTN_TOOL_FINGER, input->keybit);
+
+               __set_bit(EV_ABS, input->evbit);
+
+               /* From device specs */
+               input_set_abs_params(input, ABS_X, 0, 999, 0, 0);
+               input_set_abs_params(input, ABS_Y, 5, 239, 0, 0);
+
+               /* Calculated by hand based on usable size (156mm x 38mm) */
+               input_abs_set_res(input, ABS_X, 6);
+               input_abs_set_res(input, ABS_Y, 8);
+               break;
+
+       default:
+               BUG();
+       }
+}
+
+static void hgpk_reset_hack_state(struct psmouse *psmouse)
+{
+       struct hgpk_data *priv = psmouse->private;
+
+       priv->abs_x = priv->abs_y = -1;
+}
+
+static int hgpk_reset_device(struct psmouse *psmouse, bool recalibrate)
+{
+       int err;
+
+       psmouse_reset(psmouse);
+
+       if (recalibrate) {
+               struct ps2dev *ps2dev = &psmouse->ps2dev;
+
+               /* send the recalibrate request */
+               if (ps2_command(ps2dev, NULL, 0xf5) ||
+                   ps2_command(ps2dev, NULL, 0xf5) ||
+                   ps2_command(ps2dev, NULL, 0xe6) ||
+                   ps2_command(ps2dev, NULL, 0xf5)) {
+                       return -1;
+               }
+
+               /* according to ALPS, 150mS is required for recalibration */
+               msleep(150);
+       }
+
+       err = hgpk_select_mode(psmouse);
+       if (err) {
+               hgpk_err(psmouse, "failed to select mode\n");
+               return err;
+       }
+
+       hgpk_reset_hack_state(psmouse);
+
+       return 0;
+}
+
 static int hgpk_force_recalibrate(struct psmouse *psmouse)
 {
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        struct hgpk_data *priv = psmouse->private;
+       int err;
 
        /* C-series touchpads added the recalibrate command */
        if (psmouse->model < HGPK_MODEL_C)
        psmouse_set_state(psmouse, PSMOUSE_INITIALIZING);
 
        /* start by resetting the device */
-       psmouse_reset(psmouse);
-
-       /* send the recalibrate request */
-       if (ps2_command(ps2dev, NULL, 0xf5) ||
-           ps2_command(ps2dev, NULL, 0xf5) ||
-           ps2_command(ps2dev, NULL, 0xe6) ||
-           ps2_command(ps2dev, NULL, 0xf5)) {
-               return -1;
-       }
-
-       /* according to ALPS, 150mS is required for recalibration */
-       msleep(150);
+       err = hgpk_reset_device(psmouse, true);
+       if (err)
+               return err;
 
-       /* XXX: If a finger is down during this delay, recalibration will
+       /*
+        * XXX: If a finger is down during this delay, recalibration will
         * detect capacitance incorrectly.  This is a hardware bug, and
         * we don't have a good way to deal with it.  The 2s window stuff
         * (below) is our best option for now.
 
        psmouse_set_state(psmouse, PSMOUSE_ACTIVATED);
 
-       /* After we recalibrate, we shouldn't get any packets for 2s.  If
+       /*
+        * After we recalibrate, we shouldn't get any packets for 2s.  If
         * we do, it's likely that someone's finger was on the touchpad.
         * If someone's finger *was* on the touchpad, it's probably
         * miscalibrated.  So, we should schedule another recalibration
         */
-       priv->recalib_window = jiffies +  msecs_to_jiffies(recal_guard_time);
+       priv->recalib_window = jiffies + msecs_to_jiffies(recal_guard_time);
 
        return 0;
 }
 {
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        int timeo;
+       int err;
 
        /* Added on D-series touchpads */
        if (psmouse->model < HGPK_MODEL_D)
                        msleep(50);
                }
 
-               psmouse_reset(psmouse);
+               err = hgpk_reset_device(psmouse, false);
+               if (err) {
+                       hgpk_err(psmouse, "Failed to reset device!\n");
+                       return err;
+               }
 
                /* should be all set, enable the touchpad */
                ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_ENABLE);
 
 static int hgpk_reconnect(struct psmouse *psmouse)
 {
-       /* During suspend/resume the ps2 rails remain powered.  We don't want
+       /*
+        * During suspend/resume the ps2 rails remain powered.  We don't want
         * to do a reset because it's flush data out of buffers; however,
-        * earlier prototypes (B1) had some brokenness that required a reset. */
+        * earlier prototypes (B1) had some brokenness that required a reset.
+        */
        if (olpc_board_at_least(olpc_board(0xb2)))
                if (psmouse->ps2dev.serio->dev.power.power_state.event !=
                                PM_EVENT_ON)
                        return 0;
 
-       psmouse_reset(psmouse);
-
-       return 0;
+       return hgpk_reset_device(psmouse, false);
 }
 
 static ssize_t hgpk_show_powered(struct psmouse *psmouse, void *data, char *buf)
 __PSMOUSE_DEFINE_ATTR(powered, S_IWUSR | S_IRUGO, NULL,
                      hgpk_show_powered, hgpk_set_powered, false);
 
+static ssize_t attr_show_mode(struct psmouse *psmouse, void *data, char *buf)
+{
+       struct hgpk_data *priv = psmouse->private;
+
+       return sprintf(buf, "%s\n", hgpk_mode_names[priv->mode]);
+}
+
+static ssize_t attr_set_mode(struct psmouse *psmouse, void *data,
+                            const char *buf, size_t len)
+{
+       struct hgpk_data *priv = psmouse->private;
+       enum hgpk_mode old_mode = priv->mode;
+       enum hgpk_mode new_mode = hgpk_mode_from_name(buf, len);
+       struct input_dev *old_dev = psmouse->dev;
+       struct input_dev *new_dev;
+       int err;
+
+       if (new_mode == HGPK_MODE_INVALID)
+               return -EINVAL;
+
+       if (old_mode == new_mode)
+               return len;
+
+       new_dev = input_allocate_device();
+       if (!new_dev)
+               return -ENOMEM;
+
+       psmouse_set_state(psmouse, PSMOUSE_INITIALIZING);
+
+       /* Switch device into the new mode */
+       priv->mode = new_mode;
+       err = hgpk_reset_device(psmouse, false);
+       if (err)
+               goto err_try_restore;
+
+       hgpk_setup_input_device(new_dev, old_dev, new_mode);
+
+       psmouse_set_state(psmouse, PSMOUSE_CMD_MODE);
+
+       err = input_register_device(new_dev);
+       if (err)
+               goto err_try_restore;
+
+       psmouse->dev = new_dev;
+       input_unregister_device(old_dev);
+
+       return len;
+
+err_try_restore:
+       input_free_device(new_dev);
+       priv->mode = old_mode;
+       hgpk_reset_device(psmouse, false);
+
+       return err;
+}
+
+PSMOUSE_DEFINE_ATTR(hgpk_mode, S_IWUSR | S_IRUGO, NULL,
+                   attr_show_mode, attr_set_mode);
+
 static ssize_t hgpk_trigger_recal_show(struct psmouse *psmouse,
                void *data, char *buf)
 {
 
        device_remove_file(&psmouse->ps2dev.serio->dev,
                           &psmouse_attr_powered.dattr);
+       device_remove_file(&psmouse->ps2dev.serio->dev,
+                          &psmouse_attr_hgpk_mode.dattr);
 
        if (psmouse->model >= HGPK_MODEL_C)
                device_remove_file(&psmouse->ps2dev.serio->dev,
 
 static int hgpk_register(struct psmouse *psmouse)
 {
+       struct hgpk_data *priv = psmouse->private;
        int err;
 
        /* register handlers */
        psmouse->poll = hgpk_poll;
        psmouse->disconnect = hgpk_disconnect;
        psmouse->reconnect = hgpk_reconnect;
-       psmouse->pktsize = 3;
 
        /* Disable the idle resync. */
        psmouse->resync_time = 0;
        /* Reset after a lot of bad bytes. */
        psmouse->resetafter = 1024;
 
+       hgpk_setup_input_device(psmouse->dev, NULL, priv->mode);
+
        err = device_create_file(&psmouse->ps2dev.serio->dev,
                                 &psmouse_attr_powered.dattr);
        if (err) {
                return err;
        }
 
+       err = device_create_file(&psmouse->ps2dev.serio->dev,
+                                &psmouse_attr_hgpk_mode.dattr);
+       if (err) {
+               hgpk_err(psmouse, "Failed creating 'hgpk_mode' sysfs node\n");
+               goto err_remove_powered;
+       }
+
        /* C-series touchpads added the recalibrate command */
        if (psmouse->model >= HGPK_MODEL_C) {
                err = device_create_file(&psmouse->ps2dev.serio->dev,
                if (err) {
                        hgpk_err(psmouse,
                                "Failed creating 'recalibrate' sysfs node\n");
-                       device_remove_file(&psmouse->ps2dev.serio->dev,
-                                       &psmouse_attr_powered.dattr);
-                       return err;
+                       goto err_remove_mode;
                }
        }
 
        return 0;
+
+err_remove_mode:
+       device_remove_file(&psmouse->ps2dev.serio->dev,
+                          &psmouse_attr_hgpk_mode.dattr);
+err_remove_powered:
+       device_remove_file(&psmouse->ps2dev.serio->dev,
+                          &psmouse_attr_powered.dattr);
+       return err;
 }
 
 int hgpk_init(struct psmouse *psmouse)
 {
        struct hgpk_data *priv;
-       int err = -ENOMEM;
+       int err;
 
        priv = kzalloc(sizeof(struct hgpk_data), GFP_KERNEL);
-       if (!priv)
+       if (!priv) {
+               err = -ENOMEM;
                goto alloc_fail;
+       }
 
        psmouse->private = priv;
+
        priv->psmouse = psmouse;
        priv->powered = true;
+       priv->mode = hgpk_default_mode;
        INIT_DELAYED_WORK(&priv->recalib_wq, hgpk_recalib_work);
 
-       err = psmouse_reset(psmouse);
+       err = hgpk_reset_device(psmouse, false);
        if (err)
                goto init_fail;
 
 
        return 0;
 }
+
+void hgpk_module_init(void)
+{
+       hgpk_default_mode = hgpk_mode_from_name(hgpk_mode_name,
+                                               strlen(hgpk_mode_name));
+       if (hgpk_default_mode == HGPK_MODE_INVALID) {
+               hgpk_default_mode = HGPK_MODE_MOUSE;
+               strlcpy(hgpk_mode_name, hgpk_mode_names[HGPK_MODE_MOUSE],
+                       sizeof(hgpk_mode_name));
+       }
+}