Questions about implementing hid driver or input driver

[Axel Lin <axel.lin@gmail.com>]

Hi list,
I have a tablet that shows it is a HID device.
But the report descriptor looks broken.

Below shows the device information:

lsusb -v:

Bus 002 Device 004: ID 04b4:3045 Cypress Semiconductor Corp.
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x04b4 Cypress Semiconductor Corp.
  idProduct          0x3045
  bcdDevice            1.00
  iManufacturer           1 Ping-IT
  iProduct                2 RS232_USB
  iSerial                 0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           34
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          3 Bus power
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              4 HID
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.10
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      26
         Report Descriptors:
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10
Device Status:     0x0000
  (Bus Powered)

And below is the report descriptor ( by usbhid-dump / hidrd-convert )

0x05, 0x0D, /*  Usage Page (Digitizer),         */
0x09, 0x08, /*  Usage (3D Digitizer),           */
0xA1, 0x01, /*  Collection (Application),       */
0x09, 0x01, /*      Usage (Digitizer),          */
0xA1, 0x00, /*      Collection (Physical),      */
0x05, 0x01, /*          Usage Page (Desktop),   */
0x09, 0x3B, /*          Usage (Byte Count),     */
0x15, 0x00, /*          Logical Minimum (0),    */
0x25, 0x7F, /*          Logical Maximum (127),  */
0x75, 0x08, /*          Report Size (8),        */
0x95, 0x07, /*          Report Count (7),       */
0x81, 0x02, /*          Input (Variable),       */
0xC0,       /*      End Collection,             */
0xC0        /*  End Collection                  */

The report descriptor looks broken to me:
 1. The report descriptor does not have Usage for TOOL_PEN/STYLUS/STYLUS2/PRESSURE,
    so evdev doest not recognized it as a tablet.
    Actually, the report descriptor does not define any detail of the data.
    It only shows a 7 bytes report content.
 2. It does not have Report ID field. 
    (Does it make sense to have a report descriptor without Report ID field?)

So in this case, should I implement a HID (special device) driver or
a input driver (in drivers/input/tablet folder) for this device?

Regards,
Axel