On Mon, Aug 30, 2010 at 9:13 PM, Hans Petter Selasky <hsela...@c2i.net> wrote:
> On Monday 30 August 2010 14:41:56 Piet Skiet wrote:
>> On Mon, Aug 30, 2010 at 10:51 AM, Piet Skiet <tuks...@gmail.com> wrote:
>> > Hi,
>> >
>> > Can anyone clarify how to go about doing a synchronous usb control
>> > transfer, similar to Linux's usb_control_msg? I want to implement the
>> > TIOCMGET ioctl on a usb-to-serial converter. The Linux driver uses
>> > synchronous control messages to read DCE and CTS serial pin status,
>> > and I want to do something similar in FreeBSD. The usbdi(9) manpage
>> > talks about control transfers using usbd_transfer_submit, but they're
>> > not synchronous. What about using usbd_transfer_drain? Is there an
>> > example driver showing setting up and doing control transfers?
>> >
>> > The ucom driver seems to only implement TIOCSBRK and TIOCCBRK iotcls
>> > at the moment.
>> >
>> > Thanks
>> Scanning through the ucom code, it seems to me that the
>> usbd_do_request_proc has somehting to do with blocking control transfers.
>> Am I on the right track here?
> Yes, this is correct. You have to re-format the do request information a
> little bit compared with Linux. This function is supposed to be called from a
> UCOM callback. Please also check recent changes in USB P4:
> http://p4web.freebsd.org/@md=d&cd=//depot/projects/usb/src/sys/dev/usb/controller/&cdf=//depot/projects/usb/src/sys/dev/usb/serial/usb_serial.c&c=LJN@//depot/projects/usb/src/sys/dev/usb/serial/usb_serial.c?ac=22
> --HPS

OK, but I'm still a bit confused. I'm not sure in which callback to
put the usb_do_request. For instance, the driver that I'm interested
in is the uslcom.c driver for the cp210x usb-to-serial converter. It
has two usb_config structs defined of type UE_BULK for read and write
transfers. Do I need to add a third usb_config struct for UE_CONTROL?
Should the usb_do_request then be called from the UE_CONTROL callback?

The plan is to add a .ucom_ioctl to the uslcom.c driver and implement
the TIOCMGET directly in the driver ioctl using synchronous usb
transfers. I've already tested the .ucom_ioctl override and it works,
now I just need to figure out how to do the usb transfers.

BTW, the FTDI driver (uftdi.c) does things differently. It updates the
msr (modem status register?) in the bulk read callback and then calls
ucom_status_change to update any changes to ucom.

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