Re: [PATCH v3 1/3] usb: gadget: ccid: add support for USB CCID Gadget Device

[Marcus Folkesson <marcus.folkesson@gmail.com>]

Hi Filipe,

On Mon, Jun 18, 2018 at 11:22:04AM +0300, Felipe Balbi wrote:
> 
> Hi,
> 
> Marcus Folkesson <marcus.folkesson@gmail.com> writes:
> > Hi Felipe,
> >
> > Should I send out v4 or what do you think?
> 
> sorry for the delay, have been busy with other tasks.
> 

It is no hurry :-)

> > On Wed, May 30, 2018 at 04:04:15PM +0200, Marcus Folkesson wrote:
> >> Hi Filipe,
> >> 
> >> On Wed, May 30, 2018 at 03:28:18PM +0300, Felipe Balbi wrote:
> >> > Marcus Folkesson <marcus.folkesson@gmail.com> writes:
> >> > 
> >> > > Chip Card Interface Device (CCID) protocol is a USB protocol that
> >> > > allows a smartcard device to be connected to a computer via a card
> >> > > reader using a standard USB interface, without the need for each manufacturer
> >> > > of smartcards to provide its own reader or protocol.
> >> > >
> >> > > This gadget driver makes Linux show up as a CCID device to the host and let a
> >> > > userspace daemon act as the smartcard.
> >> > >
> >> > > This is useful when the Linux gadget itself should act as a cryptographic
> >> > > device or forward APDUs to an embedded smartcard device.
> >> > >
> >> > > Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
> >> > 
> >> > this could be done entirely in userspace with functionfs, why do we need
> >> > this part in the kernel? It does very little.
> >> 
> >> Andrzej pointed this out, and I actually do not have any good answer
> >> more than that the userspace application could be kept small and the
> >> important configuration of the CCID device is done with well (I hope)
> >> documented configfs attributes.
> 
> can we use existing open source applications without modification by
> accepting this glue layer?


If you mean existing open source application to talk to the "daemon", the answer is
yes. I have been using PCSC-lite and OpenSC on Linux, and PCSC on
Windows to communicate with the smartcard.

If you mean existing application as the "daemon", the answer is probably
no.

> 
> -- 
> balbi

Thanks,

Best regards
Marcus Folkesson


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