Hi Randy, On Tue, May 29, 2018 at 01:27:23PM -0700, Randy Dunlap wrote: > On 05/29/2018 11:50 AM, Marcus Folkesson wrote: > > Add documentation to give a brief description on how to use the > > CCID Gadget Device. > > This includes a description for all attributes followed by an example on > > how to setup the device with ConfigFS. > > > > Signed-off-by: Marcus Folkesson <marcus.folkesson@xxxxxxxxx> > > --- > > > > Notes: > > v3: > > - correct the grammer (thanks Randy) > > v2: > > - add the missing changelog text > > > > Documentation/usb/gadget_ccid.rst | 267 ++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 267 insertions(+) > > create mode 100644 Documentation/usb/gadget_ccid.rst > > > > diff --git a/Documentation/usb/gadget_ccid.rst b/Documentation/usb/gadget_ccid.rst > > new file mode 100644 > > index 000000000000..524fe9e6ac19 > > --- /dev/null > > +++ b/Documentation/usb/gadget_ccid.rst > > @@ -0,0 +1,267 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +============ > > +CCID Gadget > > +============ > > + > > +:Author: Marcus Folkesson <marcus.folkesson@xxxxxxxxx> > > + > > +Introduction > > +============ > > + > > +The CCID Gadget will present itself as a CCID device to the host system. > > +The device supports two endpoints for now; BULK IN and BULK OUT. > > +These endpoints are exposed to userspace via /dev/ccidg*. > > + > > +All CCID commands are sent on the BULK-OUT endpoint. Each command sent to the CCID > > +has an associated ending response. Some commands can also have intermediate > > +responses. The response is sent on the BULK-IN endpoint. > > +See Figure 3-3 in the CCID Specification [1]_ for more details. > > + > > +The CCID commands must be handled in userspace since the driver is only working > > +as a transport layer for the TPDUs. > > I think that it would be helpful to tell us what the naming of the /dev/ccidg* > endpoints looks like. Also, how to distinguish the BULK-IN from the BULK-OUT > endpoint. You are right, it is not clear. The devices are named as /dev/ccidg[0-4] and is per device. Writing/reading to the device is using BULK-IN/BULK-OUT, the /dev/ccidg* device is not bound to a particular endpoint. I will come up with something that make it more clear. Thank you! > > > + > > + > > +CCID Commands > > +-------------- > > + > > +All CCID commands begins with a 10-byte header followed by an optional > > +data field depending on message type. > > + > > ++--------+--------------+-------+----------------------------------+ > > +| Offset | Field | Size | Description | > > ++========+==============+=======+==================================+ > > +| 0 | bMessageType | 1 | Type of message | > > ++--------+--------------+-------+----------------------------------+ > > +| 1 | dwLength | 4 | Message specific data length | > > +| | | | | > > ++--------+--------------+-------+----------------------------------+ > > +| 5 | bSlot | 1 | Identifies the slot number | > > +| | | | for this command | > > ++--------+--------------+-------+----------------------------------+ > > +| 6 | bSeq | 1 | Sequence number for command | > > ++--------+--------------+-------+----------------------------------+ > > +| 7 | ... | 3 | Fields depends on message type | > > ++--------+--------------+-------+----------------------------------+ > > +| 10 | abData | array | Message specific data (OPTIONAL) | > > ++--------+--------------+-------+----------------------------------+ > > + > > + > > +Multiple CCID gadgets > > +---------------------- > > + > > +It is possible to create multiple instances of the CCID gadget, however, > > +a much more flexible way is to create one gadget and set the `nslots` attribute > > +to the number of desired CCID devices. > > + > > +All CCID commands specify which slot is the receiver in the `bSlot` field > > +of the CCID header. > > + > > +Usage > > +===== > > + > > +Access from userspace > > +---------------------- > > +All communication is by read(2) and write(2) to the corresponding /dev/ccidg* device. > > +Only one file descriptor is allowed to be open to the device at a time. > > > Reviewed-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > > > thanks, > -- > ~Randy Best regards, Marcus Folkesson -- 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
