From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.6 required=5.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 961847D09D for ; Tue, 29 May 2018 20:27:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966399AbeE2U1b (ORCPT ); Tue, 29 May 2018 16:27:31 -0400 Received: from merlin.infradead.org ([205.233.59.134]:58428 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966179AbeE2U1b (ORCPT ); Tue, 29 May 2018 16:27:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=2KYEBSM6qOsYCmNf42arNAtuCNETJJQkkw9V3zTjkTo=; b=hfw3IxA/oqOiQiYlLBeZP6U0Bh Kja3izgJ1pn/oVM0uaf0IgkSSHmzF8Abj6+VuSgU/9FFbPOiqI/xsOwDc2ypItYTXXxXwOI8sxMz+ 9u4Sp13o4mLbG7mgRUoKJYtvPAIVDOhFqONbHUBUqBFuMl8T9ps0p4p3rEb3+orhYbsyHhb7MLAV+ OPF/Q4Mh09q+ng7lhfDQi3W1BMTvyAgTAnhbPdFCJaB9TUZUx2WudYorRTvUe7eIVPj2qFUsnECc+ FXS3y5AMR5/bVrQhmmATDUfxNRlNvmtLyLBnjZ+m5BioUEMTMLLwcJkzaMoYC/OgB34MC9F63wasz A5BirXbQ==; Received: from static-50-53-52-16.bvtn.or.frontiernet.net ([50.53.52.16] helo=midway.dunlab) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fNlDJ-0000wZ-VX; Tue, 29 May 2018 20:27:26 +0000 Subject: Re: [PATCH v3 2/3] Documentation: usb: add documentation for USB CCID Gadget Device To: Marcus Folkesson , Greg Kroah-Hartman , Jonathan Corbet , Felipe Balbi , davem@davemloft.net, Mauro Carvalho Chehab , Andrew Morton , Ruslan Bilovol , Thomas Gleixner , Kate Stewart Cc: linux-usb@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180529185021.13738-1-marcus.folkesson@gmail.com> <20180529185021.13738-2-marcus.folkesson@gmail.com> From: Randy Dunlap Message-ID: Date: Tue, 29 May 2018 13:27:23 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180529185021.13738-2-marcus.folkesson@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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 > --- > > 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 > + > +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. > + > + > +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 thanks, -- ~Randy -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html