On Mon, 23 May 2011, Pantelis Koukousoulas wrote: > Hi, > > I 've just been looking into what would be needed to support the > one-button backup functionality in my external disk enclosure > and adaptor, because I 'm becoming fed up with windows users > posting in forums that "for me backup is just to plug the > external disk and push its button". > > Both devices have JMicron controllers inside (JM20336 for the > dual SATA -> USB enclosure and JM20337/20338 for the adaptor) > and in Windows they are handled by the PCCloneEx software by > some company called Fnet. > > These controllers are in a large variety of devices from relatively > small manufacturers and they all use the same software, so > supporting one of them will mean supporting all of the others > as well "for free" from what it seems. > > Unfortunately (as you will see from the attached lsusb output) > neither device exposes a HID interface for the button > (like Maxtor Onetouch). Instead, the JMicron people seem to use > special SCSI commands to poll for the button status. > > E.g., for the JM20338 we can see in the usbmon log a custom > CDB with command "df" and the result is 0x96 if the button > is pressed and 0x97 if not (looks like the LSB is used, active-low). > > For JM20336 it seems slightly more complex but it looks like the > method is essentially the same. > > The PCCloneEx software includes a small windows device driver > which I guess is used for this polling since I only see USB > activity on the device when this program is started. > > I attach for each chip the following: > > * lsusb output > * usbmon output (includes device initialization, 4 presses > of the button and one long hold) > > Where in the stack would I need to hack in order to add support > for this functionality? You don't need to hack anything in the stack. Just write a program that opens the device file and sends the appropriate commands using the SG_IO ioctl. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
