From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B1EBC4360C for ; Wed, 9 Oct 2019 00:04:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC0432070B for ; Wed, 9 Oct 2019 00:04:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.b="tNFH58Rg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729924AbfJIAEL (ORCPT ); Tue, 8 Oct 2019 20:04:11 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:36656 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729751AbfJIAEL (ORCPT ); Tue, 8 Oct 2019 20:04:11 -0400 Received: by mail-io1-f65.google.com with SMTP id b136so1001740iof.3 for ; Tue, 08 Oct 2019 17:04:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=odstuTaRVCUUwqpTfVbKUDeTF3SqNoCkeOZr9N3ZSWc=; b=tNFH58RgOaYfgr1X8lzsOw9lJ4w5GvOBNaeg7aN8vBuGgKE2pB0akdgkGOHNHym8X8 WqzVhsJJ/f0ZkGJKVYDlfSzXvcnGB4DF3FigNFiYF4KhzKm6WCdEloUeAfszYdC5myfL KEISEwXVJ4+vO57nJXMjI99Be024aj4u+77YBvdRJqxZkOkGka+YucEEAfSbUv+nBWA1 qV8Os7JrUXARSz+7ATFbPp8sAgx2dRMY/qNSyPfw8iSDM76ZUtr79E0cuYh4c5WihQq7 dPO/CyEbYn4Kg1iPYinVdGmXGPtQuAbjW/P9ktzCx6xNo4Z3kS72U5lB4kwUiaGadQKG DklQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=odstuTaRVCUUwqpTfVbKUDeTF3SqNoCkeOZr9N3ZSWc=; b=X9jO/Ci3ycHq5g84gNGAE6ZITRQ7sEuoYVZYDYR5+Jo/gt9KVcsGAKrCLCyf1/YIGc uWkdCg9/fmiOga8qlECQQRcJuhGRALWKRcAefxmk7/Ip8KUAtA9nVlVVknbrfkOlDdjW O6hBkhwpZV46hOfOlsQl6XLgoay6KWrv6hydzEJvGjg0JtuNWxDWoO2HHdbkTMfALafS uxXGeFNmHqNenOaMlzOYqZqhc1k+i33MYQVoiRpa1kYrsZ7s9/unoqrg+qil7LPg+0VJ Uh5pOBYmK8LqeRg6FJ0wu1EhT2GDWbzjgeByAQssuHGFsKSXXTFN26UUsPGdNyZkUM4z lvdg== X-Gm-Message-State: APjAAAUpek6yGmfKwKplaVZkqqWXtReSmi78LFYUIxB26ntbQRx2CrCX NDOGaZtEAslKjduXdkN99RKrqy5gLIkhtAHQ1ORXPg== X-Google-Smtp-Source: APXvYqxCbDBnmAe05Gb6pJ1q7XDf1vUAb7BOTowALZo1zkDgcJphN2ejo7bEIXbSmP8AhWikBzExXzWiOSwk+HRkYGM= X-Received: by 2002:a92:410c:: with SMTP id o12mr367235ila.287.1570579448915; Tue, 08 Oct 2019 17:04:08 -0700 (PDT) MIME-Version: 1.0 References: <20190921102522.8970-1-drew@pdp7.com> <20191008061512.GA19956@sol> <20191008232120.GA9225@sol> <20191008235626.GA10744@sol> In-Reply-To: <20191008235626.GA10744@sol> From: Bartosz Golaszewski Date: Wed, 9 Oct 2019 02:03:58 +0200 Message-ID: Subject: Re: [RFC] gpio: expose pull-up/pull-down line flags to userspace To: Kent Gibson Cc: Drew Fustini , "open list:GPIO SUBSYSTEM" , Linus Walleij , Thomas Petazzoni Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org =C5=9Br., 9 pa=C5=BA 2019 o 01:56 Kent Gibson napisa= =C5=82(a): > > On Wed, Oct 09, 2019 at 01:30:18AM +0200, Bartosz Golaszewski wrote: > > =C5=9Br., 9 pa=C5=BA 2019 o 01:21 Kent Gibson na= pisa=C5=82(a): > > > > > > On Tue, Oct 08, 2019 at 10:56:18PM +0200, Bartosz Golaszewski wrote: > > > > wt., 8 pa=C5=BA 2019 o 08:15 Kent Gibson nap= isa=C5=82(a): > > > > > > > > > > On Sat, Sep 21, 2019 at 12:25:23PM +0200, Drew Fustini wrote: > > > > > > Add pull-up/pull-down flags to the gpio line get and > > > > > > set ioctl() calls. Use cases include a push button > > > > > > that does not have an external resistor. > > > > > > > > > > > > Addition use cases described by Limor Fried (ladyada) of > > > > > > Adafruit in this PR for Adafruit_Blinka Python lib: > > > > > > https://github.com/adafruit/Adafruit_Blinka/pull/59 > > > > > > > > > > > > Signed-off-by: Drew Fustini > > > > > > --- > > > > > > drivers/gpio/gpiolib.c | 12 ++++++++++++ > > > > > > include/uapi/linux/gpio.h | 4 ++++ > > > > > > 2 files changed, 16 insertions(+) > > > > > > > > > > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > > > > > index d9074191edef..9da1093cc7f5 100644 > > > > > > --- a/drivers/gpio/gpiolib.c > > > > > > +++ b/drivers/gpio/gpiolib.c > > > > > > @@ -427,6 +427,8 @@ struct linehandle_state { > > > > > > (GPIOHANDLE_REQUEST_INPUT | \ > > > > > > GPIOHANDLE_REQUEST_OUTPUT | \ > > > > > > GPIOHANDLE_REQUEST_ACTIVE_LOW | \ > > > > > > + GPIOHANDLE_REQUEST_PULL_UP | \ > > > > > > + GPIOHANDLE_REQUEST_PULL_DOWN | \ > > > > > > GPIOHANDLE_REQUEST_OPEN_DRAIN | \ > > > > > > GPIOHANDLE_REQUEST_OPEN_SOURCE) > > > > > > > > > > > > @@ -598,6 +600,10 @@ static int linehandle_create(struct gpio_d= evice *gdev, void __user *ip) > > > > > > set_bit(FLAG_OPEN_DRAIN, &desc->flags); > > > > > > if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE) > > > > > > set_bit(FLAG_OPEN_SOURCE, &desc->flags); > > > > > > + if (lflags & GPIOHANDLE_REQUEST_PULL_DOWN) > > > > > > + set_bit(FLAG_PULL_DOWN, &desc->flags); > > > > > > + if (lflags & GPIOHANDLE_REQUEST_PULL_UP) > > > > > > + set_bit(FLAG_PULL_UP, &desc->flags); > > > > > > > > > > > > ret =3D gpiod_set_transitory(desc, false); > > > > > > if (ret < 0) > > > > > > @@ -1102,6 +1108,10 @@ static long gpio_ioctl(struct file *filp= , unsigned int cmd, unsigned long arg) > > > > > > if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) > > > > > > lineinfo.flags |=3D (GPIOLINE_FLAG_OPEN_S= OURCE | > > > > > > GPIOLINE_FLAG_IS_OUT); > > > > > > + if (test_bit(FLAG_PULL_DOWN, &desc->flags)) > > > > > > + lineinfo.flags |=3D GPIOLINE_FLAG_PULL_DO= WN; > > > > > > + if (test_bit(FLAG_PULL_UP, &desc->flags)) > > > > > > + lineinfo.flags |=3D GPIOLINE_FLAG_PULL_UP= ; > > > > > > > > > > > > if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))= ) > > > > > > return -EFAULT; > > > > > > @@ -2475,6 +2485,8 @@ static bool gpiod_free_commit(struct gpio= _desc *desc) > > > > > > clear_bit(FLAG_REQUESTED, &desc->flags); > > > > > > clear_bit(FLAG_OPEN_DRAIN, &desc->flags); > > > > > > clear_bit(FLAG_OPEN_SOURCE, &desc->flags); > > > > > > + clear_bit(FLAG_PULL_UP, &desc->flags); > > > > > > + clear_bit(FLAG_PULL_DOWN, &desc->flags); > > > > > > clear_bit(FLAG_IS_HOGGED, &desc->flags); > > > > > > ret =3D true; > > > > > > } > > > > > > diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpi= o.h > > > > > > index 4ebfe0ac6c5b..c2d1f7d908d6 100644 > > > > > > --- a/include/uapi/linux/gpio.h > > > > > > +++ b/include/uapi/linux/gpio.h > > > > > > @@ -33,6 +33,8 @@ struct gpiochip_info { > > > > > > #define GPIOLINE_FLAG_ACTIVE_LOW (1UL << 2) > > > > > > #define GPIOLINE_FLAG_OPEN_DRAIN (1UL << 3) > > > > > > #define GPIOLINE_FLAG_OPEN_SOURCE (1UL << 4) > > > > > > +#define GPIOLINE_FLAG_PULL_UP (1UL << 5) > > > > > > +#define GPIOLINE_FLAG_PULL_DOWN (1UL << 6) > > > > > > > > > > > > /** > > > > > > * struct gpioline_info - Information about a certain GPIO lin= e > > > > > > @@ -62,6 +64,8 @@ struct gpioline_info { > > > > > > #define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2) > > > > > > #define GPIOHANDLE_REQUEST_OPEN_DRAIN (1UL << 3) > > > > > > #define GPIOHANDLE_REQUEST_OPEN_SOURCE (1UL << 4) > > > > > > +#define GPIOHANDLE_REQUEST_PULL_UP (1UL << 5) > > > > > > +#define GPIOHANDLE_REQUEST_PULL_DOWN (1UL << 6) > > > > > > > > > > > > /** > > > > > > * struct gpiohandle_request - Information about a GPIO handle= request > > > > > > -- > > > > > > 2.20.1 > > > > > > > > > > > Sorry for the late feedback, but I'm still not sure whether this = patch > > > > > is on track to be applied or not. I had thought not, at least no= t yet, > > > > > but just in case... > > > > > > > > > > > > > It still needs some fixes, but Linus seems to be fine with the gene= ral idea. > > > > > > > > > You have added the flags to linehandle_create, but not lineevent_= create. > > > > > Given that your primary use case is push buttons, isn't the event= request > > > > > at least as important as the handle request? Even ignoring your = use > > > > > case, I'd add them to lineevent_create just to maintain symmetry. > > > > > > > > > > Also, is it valid to set PULL_UP and PULL_DOWN simulaneously? > > > > > I would think not, but I could be wrong. > > > > > If not then that combination should be rejected with EINVAL. > > > > > > > > > > > > > Yes, some validity checks of the flags must be added. I even did it= in > > > > my local branch[1]. > > > > > > > Your changes for linehandle_create look ok, but for lineevent_create > > > you explicitly disabled PULL_UP and PULL_DOWN, and in a block labelle= d > > > "This is just wrong: we don't look for events on output lines" at tha= t. > > > > > > > Yeah, feel free to change it. > > > Yeah, you see I didn't feel free to change it, as I thought the > appropriate etiquette was to send comments to the original author. > At least until the patch has been applied. > Or are RFCs a special case? > So either you review it and the author changes it and resends, or - if for example you want to build on top of someone else's changes - you take the patch, keep the original authorship, modify it and add your signed-off-by tag with a small note on your changes in square brackets. > > > > Re: direction and configuration changes on requested lines: I think > > > > it's quite useful to add in the form of a new ioctl(): > > > > GPIOHANDLE_SET_CONFIG_IOCTL or something. I started hacking on this > > > > but eventually got more busy this week than I anticipated. I'm stil= l > > > > planning on sending an RFC by the end of the week though. > > > > > > > I have the reverse problem - bored and looking for something to do, s= o > > > more than willing to help out - if you want it. > > > > > > > Sure, in that case let's just wait for your patches. You can just > > extend what I started, if you wish. > > > Yep, you sound tired. > Are we talking about the SET_CONFIG here? If you have a link to what > you've started I'll take a look, but as I've already said - I'm not > about to go writing new ioctls without approval and guidance from you > and Linus. If you have the ioctl defined I'm happy to take it from > there. Well happy-ish. > But there's absolutely nothing wrong with writing code even if you're not sure about the solution - it's even encouraged[1]. It's much easier to discuss existing code than potential solutions. [1] https://lkml.org/lkml/2000/8/25/132 > > > And while we're talking, does the gpio-mockup support pull up/down > > > being set from the kernel side? > > > > > > > No, but feel free to add it. > > > Ok, will have a look - cos I would like to add tests for the above and > that will require the mockup supporting it as wel Do you also plan on extending libgpiod by any chance? Bart > > Cheers, > Kent. >