Some elantech v3 touchpad equipped laptops also have a trackpoint, before
this commit, these give sync errors. With this patch, the trackpoint is
provided as another input device: 'Elantech PS/2 TrackPoint'

The patch will also output messages that do not follow the expected pattern.
In the mean time I've seen 2 unknown packets occasionally:
0x04 , 0x00 , 0x00 , 0x00 , 0x00 , 0x00
0x00 , 0x00 , 0x00 , 0x02 , 0x00 , 0x00
I don't know what those are for, but they can be safely ignored.

Currently all packets that are not known to v3 touchpad and where
packet[3] (the fourth byte) lowest nibble is 6 are now recognized as
PACKET_TRACKPOINT and processed by the new elantech_report_trackpoint.

This has been verified to work on a laptop Lenovo L530 where the
touchpad/trackpoint combined identify themselves as:
psmouse serio1: elantech: assuming hardware version 3 (with firmware version 0x350f02)
psmouse serio1: elantech: Synaptics capabilities query result 0xb9, 0x15, 0x0c.

Reviewed-by: Hans de Goede <redacted>
Signed-off-by: Ulrik De Bie <redacted>
---
 drivers/input/mouse/elantech.c | 119 +++++++++++++++++++++++++++++++++++++++--
 drivers/input/mouse/elantech.h |   3 ++
 2 files changed, 118 insertions(+), 4 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index ee2a04d..0eb185b 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c

@@ -403,6 +403,71 @@ static void elantech_report_absolute_v2(struct psmouse *psmouse)
        input_sync(dev);
 }

+static void elantech_report_trackpoint(struct psmouse *psmouse,
+                                      int packet_type)
+{
+       /*
+        * byte 0:  0   0 ~sx ~sy   0   M   R   L
+        * byte 1: sx   0   0   0   0   0   0   0
+        * byte 2: sy   0   0   0   0   0   0   0
+        * byte 3:  0   0  sy  sx   0   1   1   0
+        * byte 4: x7  x6  x5  x4  x3  x2  x1  x0
+        * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
+        *
+        * x and y are written in two's complement spread
+        * over 9 bits with sx/sy the relative top bit and
+        * x7..x0 and y7..y0 the lower bits.
+        * The sign of y is opposite to what the input driver
+        * expects for a relative movement
+        */
+
+       struct elantech_data *etd = psmouse->private;
+       struct input_dev *tp_dev = etd->tp_dev;
+       unsigned char *packet = psmouse->packet;
+       int x, y;
+       u32 t;
+
+       if (!tp_dev) {
+               static bool __section(.data.unlikely) __warned;
+
+               if (!__warned) {
+                       __warned = true;
+                       psmouse_err(psmouse, "Unexpected trackpoint message\n");
+                       if (etd->debug == 1)
+                               elantech_packet_dump(psmouse);
+               }
+
+               return;
+       }
+
+       input_report_key(tp_dev, BTN_LEFT, packet[0] & 0x01);
+       input_report_key(tp_dev, BTN_RIGHT, packet[0] & 0x02);
+       input_report_key(tp_dev, BTN_MIDDLE, packet[0] & 0x04);
+
+       x = ((packet[1] & 0x80) ? 0U : 0xFFFFFF00U) | packet[4];
+       y = -(int)(((packet[2] & 0x80) ? 0U : 0xFFFFFF00U) | packet[5]);
+
+       input_report_rel(tp_dev, REL_X, x);
+       input_report_rel(tp_dev, REL_Y, y);
+
+       t = (((u32)packet[0] & 0xF8) << 24) | ((u32)packet[1] << 16)
+               | (u32)packet[2] << 8 | (u32)packet[3];
+       switch (t) {
+       case 0x00808036U:
+       case 0x10008026U:
+       case 0x20800016U:
+       case 0x30000006U:
+               break;
+       default:
+               /* Dump unexpected packet sequences if debug=1 (default) */
+               if (etd->debug == 1)
+                       elantech_packet_dump(psmouse);
+               break;
+       }
+
+       input_sync(tp_dev);
+}
+
 /*
  * Interpret complete data packets and report absolute mode input events for
  * hardware version 3. (12 byte packets for two fingers)

@@ -715,6 +780,8 @@ static int elantech_packet_check_v3(struct psmouse *psmouse)

                if ((packet[0] & 0x0c) == 0x0c && (packet[3] & 0xce) == 0x0c)
                        return PACKET_V3_TAIL;
+               if ((packet[3] & 0x0f) == 0x06)
+                       return PACKET_TRACKPOINT;
        }

        return PACKET_UNKNOWN;

@@ -798,7 +865,10 @@ static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
                if (packet_type == PACKET_UNKNOWN)
                        return PSMOUSE_BAD_DATA;

-               elantech_report_absolute_v3(psmouse, packet_type);
+               if (packet_type == PACKET_TRACKPOINT)
+                       elantech_report_trackpoint(psmouse, packet_type);
+               else
+                       elantech_report_absolute_v3(psmouse, packet_type);
                break;

        case 4:

@@ -1018,8 +1088,10 @@ static int elantech_get_resolution_v4(struct psmouse *psmouse,
  * Asus UX31               0x361f00        20, 15, 0e      clickpad
  * Asus UX32VD             0x361f02        00, 15, 0e      clickpad
  * Avatar AVIU-145A2       0x361f00        ?               clickpad
+ * Fujitsu H730            0x570f00        c0, 14, 0c      3 hw buttons (**)
  * Gigabyte U2442          0x450f01        58, 17, 0c      2 hw buttons
  * Lenovo L430             0x350f02        b9, 15, 0c      2 hw buttons (*)
+ * Lenovo L530             0x350f02        b9, 15, 0c      2 hw buttons (*)
  * Samsung NF210           0x150b00        78, 14, 0a      2 hw buttons
  * Samsung NP770Z5E        0x575f01        10, 15, 0f      clickpad
  * Samsung NP700Z5B        0x361f06        21, 15, 0f      clickpad

@@ -1029,6 +1101,8 @@ static int elantech_get_resolution_v4(struct psmouse *psmouse,
  * Samsung RF710           0x450f00        ?               2 hw buttons
  * System76 Pangolin       0x250f01        ?               2 hw buttons
  * (*) + 3 trackpoint buttons
+ * (**) + 0 trackpoint buttons
+ * Note: Lenovo L430 and Lenovo L430 have the same fw_version/caps
  */
 static void elantech_set_buttonpad_prop(struct psmouse *psmouse)
 {

@@ -1324,6 +1398,10 @@ int elantech_detect(struct psmouse *psmouse, bool set_properties)
  */
 static void elantech_disconnect(struct psmouse *psmouse)
 {
+       struct elantech_data *etd = psmouse->private;
+
+       if (etd->tp_dev)
+               input_unregister_device(etd->tp_dev);
        sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
                           &elantech_attr_group);
        kfree(psmouse->private);

@@ -1438,8 +1516,10 @@ static int elantech_set_properties(struct elantech_data *etd)
 int elantech_init(struct psmouse *psmouse)
 {
        struct elantech_data *etd;
-       int i, error;
+       int i;
+       int error = -EINVAL;
        unsigned char param[3];
+       struct input_dev *tp_dev;

        psmouse->private = etd = kzalloc(sizeof(struct elantech_data), GFP_KERNEL);
        if (!etd)

@@ -1498,14 +1578,45 @@ int elantech_init(struct psmouse *psmouse)
                goto init_fail;
        }

+       /* The MSB indicates the presence of the trackpoint */
+       if ((etd->capabilities[0] & 0x80) == 0x80) {
+               tp_dev = input_allocate_device();
+               if (!tp_dev)
+                       goto init_fail_tp_alloc;

+
+               etd->tp_dev = tp_dev;
+               snprintf(etd->tp_phys, sizeof(etd->tp_phys), "%s/input1",
+                       psmouse->ps2dev.serio->phys);
+               tp_dev->phys = etd->tp_phys;
+               tp_dev->name = "Elantech PS/2 TrackPoint";
+               tp_dev->id.bustype = BUS_I8042;
+               tp_dev->id.vendor  = 0x0002;
+               tp_dev->id.product = PSMOUSE_ELANTECH;
+               tp_dev->id.version = 0x0000;
+               tp_dev->dev.parent = &psmouse->ps2dev.serio->dev;
+               tp_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
+               tp_dev->relbit[BIT_WORD(REL_X)] =
+                       BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+               tp_dev->keybit[BIT_WORD(BTN_LEFT)] =
+                       BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_MIDDLE) |
+                       BIT_MASK(BTN_RIGHT);
+               error = input_register_device(etd->tp_dev);
+               if (error < 0)
+                       goto init_fail_tp_reg;
+       }
+
        psmouse->protocol_handler = elantech_process_byte;
        psmouse->disconnect = elantech_disconnect;
        psmouse->reconnect = elantech_reconnect;
        psmouse->pktsize = etd->hw_version > 1 ? 6 : 4;

        return 0;
-
+ init_fail_tp_reg:
+       input_free_device(tp_dev);
+ init_fail_tp_alloc:
+       sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
+                          &elantech_attr_group);
  init_fail:
        kfree(etd);
-       return -1;
+       return error;
 }

diff --git a/drivers/input/mouse/elantech.h b/drivers/input/mouse/elantech.h
index 9e0e2a1..e410336 100644
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h

@@ -94,6 +94,7 @@
 #define PACKET_V4_HEAD                 0x05
 #define PACKET_V4_MOTION               0x06
 #define PACKET_V4_STATUS               0x07
+#define PACKET_TRACKPOINT              0x08

 /*
  * track up to 5 fingers for v4 hardware

@@ -114,6 +115,8 @@ struct finger_pos {
 };

 struct elantech_data {
+       struct input_dev *tp_dev;       /* Relative device for trackpoint */
+       char    tp_phys[32];
        unsigned char reg_07;
        unsigned char reg_10;
        unsigned char reg_11;
--

2.0.0