HID: alps: add support for Alps T4 Touchpad device

- Define T4 device specification value for support T4 device.

- Creeate "t4_contact_data" and "t4_input_report" structure for decoding and
  storing T4-specific data

- Create "t4_calc_check_sum()" function for calculating checksum value to send
  to the device. T4 needs to send this value when reading or writing device
  address value.

- Create "t4_read_write_register()" function for reading and writing device
  address value.

- Create "t4_raw_event()" function for decodin XYZ, palm and button data.

- Replace "MAX_TOUCHES" fixed variable to "max_fingers" variable.

- Add T4 devuce product ID. (0x120C)

T4 device is used on HP EliteBook 1000 series and Zbook Stduio

[jkosina@suse.cz: rewrite changelog]
Signed-off-by: Masaki Ota <masaki.ota@jp.alps.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -1889,6 +1889,8 @@ static const struct hid_device_id hid_have_special_driver[] = {
 #endif
 #if IS_ENABLED(CONFIG_HID_ALPS)
 	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_ANY, USB_VENDOR_ID_ALPS_JP, HID_DEVICE_ID_ALPS_U1_DUAL) },
+	{ HID_I2C_DEVICE(USB_VENDOR_ID_ALPS_JP, HID_DEVICE_ID_ALPS_U1_DUAL) },
+	{ HID_I2C_DEVICE(USB_VENDOR_ID_ALPS_JP, HID_DEVICE_ID_ALPS_T4_BTNLESS) },
 #endif
 #if IS_ENABLED(CONFIG_HID_APPLE)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MIGHTYMOUSE) },

drivers/hid/hid-ids.h

@@ -77,6 +77,8 @@
 #define HID_DEVICE_ID_ALPS_U1_DUAL	0x120B
 #define HID_DEVICE_ID_ALPS_U1_DUAL_PTP	0x121F
 #define HID_DEVICE_ID_ALPS_U1_DUAL_3BTN_PTP	0x1220
+#define HID_DEVICE_ID_ALPS_T4_BTNLESS	0x120C
+
 
 #define USB_VENDOR_ID_AMI		0x046b
 #define USB_DEVICE_ID_AMI_VIRT_KEYBOARD_AND_MOUSE	0xff10