From owner-freebsd-arm@FreeBSD.ORG Fri Apr 17 13:26:00 2015 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 133BE776; Fri, 17 Apr 2015 13:26:00 +0000 (UTC) Received: from kabab.cs.huji.ac.il (kabab.cs.huji.ac.il [132.65.116.210]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id B7CB0FD6; Fri, 17 Apr 2015 13:25:59 +0000 (UTC) Received: from mbpro2.bs.cs.huji.ac.il ([132.65.179.20]) by kabab.cs.huji.ac.il with esmtp id 1Yj6HN-000AJ5-0p; Fri, 17 Apr 2015 16:25:57 +0300 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2090\)) Subject: Re: help with coding a loadable kernel module From: Daniel Braniss In-Reply-To: <1429276417.1182.71.camel@freebsd.org> Date: Fri, 17 Apr 2015 16:26:04 +0300 Cc: Tom Jones , freebsd-arm@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20150417080839.GO2743@home.opsec.eu> <9B835088-661C-456E-84A7-47BC1835C0CB@cs.huji.ac.il> <20150417095536.GA38091@gmail.com> <32D7EBD3-813E-4062-8A06-ED8E82BA50DA@cs.huji.ac.il> <1429276417.1182.71.camel@freebsd.org> To: Ian Lepore X-Mailer: Apple Mail (2.2090) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Apr 2015 13:26:00 -0000 > On Apr 17, 2015, at 4:13 PM, Ian Lepore wrote: >=20 > On Fri, 2015-04-17 at 13:46 +0300, Daniel Braniss wrote: >>> On Apr 17, 2015, at 12:55 PM, Tom Jones wrote: >>>=20 >>> On Fri, Apr 17, 2015 at 12:15:33PM +0300, Daniel Braniss wrote: >>>>=20 >>>>> On Apr 17, 2015, at 11:08 AM, Kurt Jaeger wrote: >>>>>=20 >>>>> Hi! >>>>>=20 >>>>>> I know I'm embarking on a dangerous trip, but I want to use a = Raspberry Pi >>>>>> and or a BeagleBone to read (and write) RFID cards. >>>>>> Since a driver is needed to use the spibus, I have 2 options = while >>>>>> developing: >>>>> [...] >>>>>> So before I give up on option 2, is there some examples/help? >>>>>=20 >>>>> Are you aware of this book ? >>>>>=20 >>>>> http://www.nostarch.com/bsddrivers.htm = >>>>=20 >>>> no, but before I spend more money (this is getting expensive :-), >>>> does it explain how to write a loadable module that needs to to = talk >>>> to a spibus?=20 >>>=20 >>> I don't think it does. >>>=20 >>> spibus is very simple, there is one interface call >>>=20 >>> SPIBUS_TRANSFER(device_t, device_t, strcut spi_command); >>>=20 >>=20 >> chicken and egg issue :-), what device_t dev should I use? >> it must point to the spibus =E2=80=A6 >=20 > Your device will be a child of the spibus, and it is the bus that it=E2=80=99s the =E2=80=98child of=E2=80=99 that I have problems. this = will be a loadable module, so it will have to tell the parent that he is no longer an orphan :-) > implements the SPIBUS_TRANSFER() method, so it's the bus's device_t = that > needs to be passed as the first parameter in the call (if it were C++ = it > would be the "this" pointer -- this stuff is OO implemented in = plain-C). >> =46rom your driver, something like: >=20 > SPIBUS_TRANSFER(device_get_parent(sc->sc_dev), sc->sc_dev, cmdptr); >=20 > I haven't got time this morning to put together a complete example of > how to add a module to the build, but the process is basically along = the > lines of... >=20 > Add a new directory to sys/dev for your driver just like you were > going to compile it into the kernel. Then in sys/modules find another > simple driver, copy it to a new directory, and change the names of > things in the makefile so that it refers to your new dir/files in > sys/dev. You can set MODULES_OVERRIDE=3Dyournew_dirname on the make > command line or in your kernel config to make it compile. >=20 I have that, even figured out how to cross compile and use the make = buildenv. it=E2=80=99s great! I can compile outside the source tree too. thanks, danny