Input: ALPS - detect trackstick presence for v7 protocol

This patch adds detection of trackstick for v7 protocol devices. Code in
this patch is used in official Dell touchpad linux drivers for Dell models:
Dell Latitude E5250/5250, E5450/5450, E5550/5550

Detection code and base reg for alps v3 rushmore and v7 devices is exacly
same.

Also user in bug https://bugzilla.kernel.org/show_bug.cgi?id=94801 reported
that Toshiba Sattellite Z30-A-1DG has only alps v7 touchpad device without
trackstick and kernel reports to userspace also redundant trackstick
device.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Alex Hung <alex.hung@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/alps.c

@@ -31,6 +31,7 @@
 #define ALPS_CMD_NIBBLE_10	0x01f2
 
 #define ALPS_REG_BASE_RUSHMORE	0xc2c0
+#define ALPS_REG_BASE_V7	0xc2c0
 #define ALPS_REG_BASE_PINNACLE	0x0000
 
 static const struct alps_nibble_commands alps_v3_nibble_commands[] = {
@@ -2047,7 +2048,7 @@ static int alps_absolute_mode_v3(struct psmouse *psmouse)
 	return 0;
 }
 
-static int alps_probe_trackstick_v3(struct psmouse *psmouse, int reg_base)
+static int alps_probe_trackstick_v3_v7(struct psmouse *psmouse, int reg_base)
 {
 	int ret = -EIO, reg_val;
 
@@ -2132,7 +2133,7 @@ static int alps_hw_init_v3(struct psmouse *psmouse)
 	int reg_val;
 	unsigned char param[4];
 
-	reg_val = alps_probe_trackstick_v3(psmouse, ALPS_REG_BASE_PINNACLE);
+	reg_val = alps_probe_trackstick_v3_v7(psmouse, ALPS_REG_BASE_PINNACLE);
 	if (reg_val == -EIO)
 		goto error;
 
@@ -2625,8 +2626,8 @@ static int alps_set_protocol(struct psmouse *psmouse,
 		priv->x_bits = 16;
 		priv->y_bits = 12;
 
-		if (alps_probe_trackstick_v3(psmouse,
-					     ALPS_REG_BASE_RUSHMORE) < 0)
+		if (alps_probe_trackstick_v3_v7(psmouse,
+						ALPS_REG_BASE_RUSHMORE) < 0)
 			priv->flags &= ~ALPS_DUALPOINT;
 
 		break;
@@ -2676,6 +2677,9 @@ static int alps_set_protocol(struct psmouse *psmouse,
 		if (priv->fw_ver[1] != 0xba)
 			priv->flags |= ALPS_BUTTONPAD;
 
+		if (alps_probe_trackstick_v3_v7(psmouse, ALPS_REG_BASE_V7) < 0)
+			priv->flags &= ~ALPS_DUALPOINT;
+
 		break;
 
 	case ALPS_PROTO_V8: