Support Touchscreen SoundGraph

[xavier hervy <xavier.hervy@bluebottle.com>]

Hi,
I am trying to make my touch screen work (Zalman HD160XT Plus) but I
could not find any suitable driver for it.
The Touch screen is an USB Device which consist of :
- a touch screen
- a knob
- few buttons in a front panel
- A remote control
lsusb -v

Bus 004 Device 004: ID 15c2:0034 SoundGraph Inc. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x15c2 SoundGraph Inc.
  idProduct          0x0034 
  bcdDevice            0.12
  iManufacturer           0 
  iProduct                0 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           59
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Devices
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      2 Mouse
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.01
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength     121
         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
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Devices
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.00
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      50
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10
Device Status:     0x0000
  (Bus Powered)

I am currently running Ubuntu 7.10
Two input device are created when plugged:
lrwxrwxrwx 1 root root   9 2008-09-04 22:56 usb-15c2_0034-event-mouse
-> ../event1
lrwxrwxrwx 1 root root   9 2008-09-04 22:56 usb-15c2_0034-mouse
-> ../mouse1

As well as  /dev/usb/hiddev0

The input device does give me anything usefull but the hiddev0 device
provide me some infos:
A packet seems to be 64 Bytes  (in opposite two 2 * 8 Bytes according to
lsusb)
The knob and buttons seem quiet easily to decode:
Example knob -: (the 5th bytes is equal to 1)
[03 00 cd ff 01 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 12 00 00 00] 
[04 00 cd ff ee ff ff ff] 

Example knob -: (the 13th bytes is equal to 1)
[03 00 cd ff 00 00 00 00] 
[04 00 cd ff 01 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 00 00 00 00] 
[04 00 cd ff 12 00 00 00] 
[04 00 cd ff ee ff ff ff] 
For the front panel button the 29th bytes change (I suppose the remote
work the same way but I didn't try for a while)

For the touch screen it self, I did not manage to understand fully what
is been sent but my packet look like
[03 00 cd ff dd ff ff ff ... 
with the 5th byte value changing according to Y (or X) axe and  the 6th,
7th and 9th to FF

Does anybody know a driver capable to support this protocol.
If not, I am willing to write the drive for it but I will need a lot of
help too as I never wrote any driver before.
How does it work when the same device is used like a keyboard and a
touch screen ?

Why the wMaxPacketSize is set at 8 Bytes when the size seems to be 64 ?

Where should I start ?

Regards,

Xavier