From owner-freebsd-drivers@freebsd.org Thu Mar 26 00:24:06 2020 Return-Path: Delivered-To: freebsd-drivers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id EADF1268B28 for ; Thu, 26 Mar 2020 00:24:05 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gate2.funkthat.com", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 48nm1f5hMgz4Zsn for ; Thu, 26 Mar 2020 00:23:50 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.15.2/8.15.2) with ESMTPS id 02Q0NdtR012811 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 25 Mar 2020 17:23:39 -0700 (PDT) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.15.2/8.15.2/Submit) id 02Q0Ncui012808; Wed, 25 Mar 2020 17:23:38 -0700 (PDT) (envelope-from jmg) Date: Wed, 25 Mar 2020 17:23:38 -0700 From: John-Mark Gurney To: "Wall, Stephen" Cc: "freebsd-drivers@freebsd.org" Subject: Re: Sending data packets to USB bulk endpoint Message-ID: <20200326002338.GS4213@funkthat.com> Mail-Followup-To: "Wall, Stephen" , "freebsd-drivers@freebsd.org" References: <14d06ca2f98e42eca84e9b0d0df8b39e@redcom.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <14d06ca2f98e42eca84e9b0d0df8b39e@redcom.com> X-Operating-System: FreeBSD 11.3-STABLE amd64 X-PGP-Fingerprint: D87A 235F FB71 1F3F 55B7 ED9B D5FF 5A51 C0AC 3D65 X-Files: The truth is out there X-URL: https://www.funkthat.com/ X-Resume: https://www.funkthat.com/~jmg/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.6.1 (2016-04-27) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (gold.funkthat.com [127.0.0.1]); Wed, 25 Mar 2020 17:23:39 -0700 (PDT) X-Rspamd-Queue-Id: 48nm1f5hMgz4Zsn X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of jmg@gold.funkthat.com has no SPF policy when checking 208.87.223.18) smtp.mailfrom=jmg@gold.funkthat.com X-Spamd-Result: default: False [-0.35 / 15.00]; ARC_NA(0.00)[]; TO_DN_EQ_ADDR_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; NEURAL_HAM_MEDIUM(-0.61)[-0.615,0]; RBL_NIXSPAM_FAIL(0.00)[18.223.87.208.ix.dnsbl.manitu.net:query timed out]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[funkthat.com]; AUTH_NA(1.00)[]; RBL_VIRUSFREE_UNKNOWN_FAIL(0.00)[18.223.87.208.bip.virusfree.cz:query timed out]; NEURAL_HAM_LONG(-0.54)[-0.544,0]; TO_MATCH_ENVRCPT_SOME(0.00)[]; IP_SCORE(-0.39)[ip: (-1.01), ipnet: 208.87.216.0/21(-0.51), asn: 32354(-0.41), country: US(-0.05)]; RCPT_COUNT_TWO(0.00)[2]; R_SPF_NA(0.00)[]; FORGED_SENDER(0.30)[jmg@funkthat.com,jmg@gold.funkthat.com]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:32354, ipnet:208.87.216.0/21, country:US]; FROM_NEQ_ENVFROM(0.00)[jmg@funkthat.com,jmg@gold.funkthat.com]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-drivers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Writing device drivers for FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Mar 2020 00:24:06 -0000 Wall, Stephen wrote this message on Wed, Mar 25, 2020 at 01:53 +0000: > I posted this on the FreeBSD Drivers forum, got no response, so I'm trying here. > > I am working on a driver to support a Silicon Labs I2S to USB bridge. Besides the audio portion, the chip supports a bulk endpoint which uses a documented packet format to read & control 16 GPIO pins, and to pass messages to & from an I2C bus. I have not previously worked with USB, or FreeBSD drivers. I'm been handed a partially complete codebase - the audio stream works - and I'm trying to get the GPIO controls working. My intent is to use ioctl() calls to read and set the pins. > > Creating an entry in /dev and the associated character device structure for the GPIO control is pretty straightforward. Where I'm getting stuck is trying to figure out how to get the messages I am creating in the driver down to the bulk endpoint - the USB driver code is a bit overwhelming to a newcomer, and I can't seem to find a function that fits "send this block of data to this endpoint". The only way I've seen for interacting with bulk endpoints is to write a driver based on usb_fifo_methods rather than cdevsw (per "FreeBSD Device Drivers", chapter 15), which does not seem to fit what I'm trying to do. > > I would appreciate any pointers experienced driver developers could give me to get where I'm trying to go with this - either the name of the function I'm looking for, or some other was to get that functionality. Is there a specific reason you want a native kernel driver instead of using something like libusb + cuse4bsd? Also, have you looked at usbdi(9)? It looks like it contains the information on how to setup a transfer w/ the buffer, and use that. https://www.freebsd.org/cgi/man.cgi?query=usbdi&manpath=FreeBSD+12.1-RELEASE+and+Ports -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."