From mboxrd@z Thu Jan 1 00:00:00 1970 From: Markus Pargmann Subject: Re: [PATCH 0/6] GPIO character device skeleton Date: Tue, 03 Nov 2015 08:39:13 +0100 Message-ID: <2109736.Oi4ERkUO0L@adelgunde> References: <1445502750-22672-1-git-send-email-linus.walleij@linaro.org> <20151101024144.GF28319@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1993466.G3OXs7KGJK"; micalg="pgp-sha256"; protocol="application/pgp-signature" Return-path: Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:46266 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788AbbKCHjR (ORCPT ); Tue, 3 Nov 2015 02:39:17 -0500 In-Reply-To: <20151101024144.GF28319@sirena.org.uk> Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Mark Brown Cc: Linus Walleij , Alexandre Courbot , "linux-gpio@vger.kernel.org" , Johan Hovold , Alexandre Courbot , Arnd Bergmann , Michael Welling , Amit Kucheria --nextPart1993466.G3OXs7KGJK Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" On Sunday 01 November 2015 11:41:44 Mark Brown wrote: > On Fri, Oct 30, 2015 at 08:47:14PM +0100, Linus Walleij wrote: > > On Fri, Oct 30, 2015 at 2:55 AM, Alexandre Courbot wrote: >=20 > > > * For all the justified hate that sysfs got, it had the advantage= of > > > being directly accessible using only the shell. If we replace it = with > > > a character device interface, I think we will need a "libgpio" (t= hat > > > provides easy access to C programs) and "gpio-tools" (simple > > > command-line tools that provide functionality similar to the sysf= s > > > interface). Are we ready to start and maintain these? Granted, it= > > > should not be too much work, but it's still an extra. >=20 > > I think the raw ioctl()s will be simple enough and intend to use > > the tools/gpio/* as proper examples. If we need > > tools/gpio/swiss-army-knife.c we will add it too. >=20 > > ALSA and fbdev and MESA and libusb spawned huge userspace > > libs, but I hope this ioctl() ABI will be simple enough that apps > > can use it directly without a lib. But what do I know. >=20 > That only works for very C like languages, for other languages (thing= s > like scripting languages in particular) you're going to need a librar= y > for the language to bind to in order to be usable. I think we need real gpio userspace tools for such a chardev interface = and not only a library. On the one hand there are all the kernel/userspace deve= lopers that just want to test stuff. On the other hand there are really a lot = of people that are using small embedded devices (e.g. beaglebone, raspberr= y pi, ...) for really simple applications like using GPIOs to control somethi= ng. I am sure many of them are just using some really simple bash code to reach = their goals. Best Regards, Markus =2D-=20 Pengutronix e.K. | = | Industrial Linux Solutions | http://www.pengutronix.de/= | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 = | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-555= 5 | --nextPart1993466.G3OXs7KGJK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJWOGShAAoJEEpcgKtcEGQQV/8QAKDHJQ+eKlJC0CMvqW9MMx1p NkEdDLsnPP7eT4sHc5uDj17fz24hMphzctRMM8MPrxyT8Sti1+O61afJH44K8gDP 0hBhSLAQn6Ss2w+bV6TKKjGMOEkTNcvBhMF0jRYpLPG3VMJnh0ABuMFRC0o6TzgB LvXWEwD3LC1c3lYZzEpBpIzzbWecroDyPaBmIiw8zE9jjp0VL7f1hmYQSjpU0U4a lUYY6K03g2+hS1c2b6rnvgid12yHzRbQXdN3m6U/E6E4NlslY1kY52+jkPv2I2wK GVzn1ay3utuNkn9i7ex8DuYBhqbP+PZ4QoQ+PNO04F2XnOH6OoWLgcEDY5+ziBPM 1Gv/DeMC9emlMi+OUIrvkViEUmG8ovsFASgaJFTAucsaduJFKd2b6pU7nJJ/Q1Ly o5vTmvkzcdP5Bnp0l6SmUVQaLUupLP0DJajdWNlzgNH474wOvyCYhYesUJI4friM HGQftvNrlKUSVUqhuya0TQirHW9BqXcg+voJDfVv5jnf16vcWXOGVTJS5joDSeMo pDPM7BfJK+eVLZ8albKgNxe7GhHu74sXEjodR1MEs+vwG3gRyL9+OSH8LvR0QNHH 5ZFF1pJe2xgT9ZYDrbWmVAfCtabu7udQLmH6SEYxxNhJ6cp1zndFuwbMvD4tXCmp lEiV2zle5+9ULeDLfm8Q =nd/a -----END PGP SIGNATURE----- --nextPart1993466.G3OXs7KGJK--