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 3AC20C4360C for ; Tue, 8 Oct 2019 20:56:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 045312070B for ; Tue, 8 Oct 2019 20:56:31 +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="sXrU7LbM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730674AbfJHU4a (ORCPT ); Tue, 8 Oct 2019 16:56:30 -0400 Received: from mail-io1-f66.google.com ([209.85.166.66]:43108 "EHLO mail-io1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730523AbfJHU4a (ORCPT ); Tue, 8 Oct 2019 16:56:30 -0400 Received: by mail-io1-f66.google.com with SMTP id v2so10704iob.10 for ; Tue, 08 Oct 2019 13:56:29 -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=Wmsr2+NbooE37zc4TqI/pDqJ/l6O1dpzuZOv8JzlCHI=; b=sXrU7LbMKpB3BHoXPqY7OD5rifX27B7m+WOulT9tl8MFDCJ7WUyebnPGuKhfosZ5QS xl7PSKsNBAVmvHpVZJXjKHUiJgmjOWk9rJgHgdcoxeFScz6LssQNc+eDgiXtDMeSDr1G YuvfJc2VMKLozjtOW2S/7lumyhFSq0LfV99na+X2CS7G8rMUVpL1XEYqLg8EXgTSnU36 3BJf6jCkMFR+oj6IzVKzQ/PzRB/s1DNubGINudDdikZCmGw4rBPwi2BToFlDrDDnJbqX 6KaVJkaYoF3Lad+XHWQEi2BaLsmy460SbtJR3Asncc3e8JnuvcfcPdud1VSg/dG4cmqu OjVA== 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=Wmsr2+NbooE37zc4TqI/pDqJ/l6O1dpzuZOv8JzlCHI=; b=ZCrX8dXJxscbv7LqKAjQg4jxPt6TSnqXNjGcPxqOhfNGqRbKw4SYuRD3d5HHZUMNYv ZYkKlZ+9bIxkBUCnfiVIKREZSZ+ThLwbUseVDfqLrc7SCKbMYdQMUlvQjOHk3ifZq3wf BmdZUhEAao0pM3mLd+kTX+W/rASlXlXGgR5f2BZhXu6fDboR/K9++6DtFqfxKSXvKseF QJGfM7na8GmUcDvhItLZqwBamMS9h9Ai7wnTM7WP/qKqxFHpPBOY40SApwRX0YZfpOMg yHRUxBgefC7afbDmjAfAku7qbCYlHZWo1Vq3PEhrOrcXwM55hgzvUKSVr35gKRAXpBEe pPxg== X-Gm-Message-State: APjAAAUBizXW0pSxhUmqmjdMDLszVlaXm1Pxz6S7OMK173FGOD2OeWT4 dfnclAYbxPaLQXWLrRbHHHQ9rFTbtyv8U3xIuTaoKA== X-Google-Smtp-Source: APXvYqx1ctfr0pWoeNRAA582n9nESUUU67OLCMxF1bCOijYfruqD8LUjuLsM63su0GKIGLGTDX8WowGZ/bmBktHay6Y= X-Received: by 2002:a5e:db46:: with SMTP id r6mr135597iop.287.1570568189012; Tue, 08 Oct 2019 13:56:29 -0700 (PDT) MIME-Version: 1.0 References: <20190921102522.8970-1-drew@pdp7.com> <20191008061512.GA19956@sol> In-Reply-To: <20191008061512.GA19956@sol> From: Bartosz Golaszewski Date: Tue, 8 Oct 2019 22:56:18 +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 wt., 8 pa=C5=BA 2019 o 08:15 Kent Gibson napisa=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_device *g= dev, 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, unsign= ed int cmd, unsigned long arg) > > if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) > > lineinfo.flags |=3D (GPIOLINE_FLAG_OPEN_SOURCE | > > GPIOLINE_FLAG_IS_OUT); > > + if (test_bit(FLAG_PULL_DOWN, &desc->flags)) > > + lineinfo.flags |=3D GPIOLINE_FLAG_PULL_DOWN; > > + 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 *d= esc) > > 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/gpio.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 line > > @@ -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 not yet, > but just in case... > It still needs some fixes, but Linus seems to be fine with the general 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]. 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 still planning on sending an RFC by the end of the week though. Bart [1] https://github.com/brgl/linux/commit/82fc38f6ab599ee03f7a8ed078de8abb41= e6e611 > Cheers, > Kent.