The main difference with the USB HID communication is that the BLE data
packets have a variable size and are no longer padded to the full 32
(Tx) or 64 (Rx) bytes.
Currently the dive computer backends are responsible for opening (and
closing) the underlying I/O stream internally. The consequence is that
each backend is hardwired to a specific transport type (e.g. serial,
irda or usbhid). In order to remove this dependency and support more
than one transport type in the same backend, the opening (and closing)
of the I/O stream is moved to the application.
The dc_device_open() function is modified to accept a pointer to the I/O
stream, instead of a string with the device node (which only makes sense
for serial communication). The dive computer backends only depend on the
common I/O interface.
The communication protocol is identical to the G2 protocol, but with a
different USB VID/PID (c251:2006).
Note that unlike the G2, the Aladin Square seems to support only 33 byte
USB HID packets (1 byte report id and 32 bytes payload), even when the
actual command is much smaller. Without padding the commands, the dive
computer doesn't reply at all. Because the padding is already there, to
support the Windows api, no further changes are necessary.
The Windows HID api always expects to receive a fixed size buffer
(corresponding to the largest report supported by the device). But
unlike the hidapi library, the libusb library doesn't automatically pad
the buffer to the expected size when trying to send less bytes. Thus
when trying to submit the transfer, the underlying Windows api call
immediately fails with ERROR_INVALID_PARAMETER.
To workaround this problem, pad the data packet with zeros manually and
always send the entire packet (1 byte report ID and 32 bytes payload).
Being able to synchronize the dive computer clock with the host system
is a very useful feature. Add the infrastructure to support this feature
through the public api.
The zero report ID byte is required when using the hidapi library. We
just never noticed this problem before, because we use libusb by
default, and libusb doesn't need the extra zero byte.
At the moment, the progress reporting will jump straight from about 0%
at the start of the download to 100% at the end of the download, without
any updates in between. This is improved by updating after every packet.
The error code returned by the dc_usbhid_read() function should be
returned as-is, instead of being replaced with some generic error, which
gets translated again to DC_STATUS_IO in the caller.
I did the packet logging for the received data side, but forgot to do
the same thing on the command transfer side, which makes the debug logs
a bit less useful.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When doing the G2 downloader, I dropped the initial handshake as I tried
to keep the code minimal, and the handshake didn't seem to make any
difference what-so-ever to me.
And it probably doesn't matter for anybody else either. But the code
isn't working for some people, and maybe it does actually matter.
More importantly, Scubapro's own LogTRAK application does send those two
initial commands, and it's probably a good idea to minimize the
differences between the different downloaders anyway, so add the
handshake sequence back in.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jef Driesen correctly points out that the 'address' field is just
leftover from the IrDA code, and is meaningless for the USB HID
transport version of the Scubapro G2.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The back-end parser seems to be the same as for the Uwatec Smart (aka
Galileo Sol). At least that's the assumption right now.
The downloader just uses USB HID (very similar to EON Steel) rather than
the horrible IrDA thing.
There's also eventually a BLE thing, but that's for the future.
This is an unholy mixture of the Uwatec Smart downloader logic and the
EON Steel usbhid transfer code. The back-end is pure Uwatec Smart
(model 0x11, same as Galileo Sol).
I'm not at all sure this gets everything right, but it downloads
*something*.
[Jef Driesen: Renamed the backend to uwatec, and made some smaller
cosmetic changes to match the existing coding style.]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
