From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Kent Gibson <warthog618@gmail.com>
Cc: Drew Fustini <drew@pdp7.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [RFC] gpio: expose pull-up/pull-down line flags to userspace
Date: Tue, 8 Oct 2019 22:56:18 +0200 [thread overview]
Message-ID: <CAMRc=Mf8DsEOWcX2BTtdVtsRkNXB3oA-xt2SrWJTn6vt3Fd8Pg@mail.gmail.com> (raw)
In-Reply-To: <20191008061512.GA19956@sol>
wt., 8 paź 2019 o 08:15 Kent Gibson <warthog618@gmail.com> napisał(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 <drew@pdp7.com>
> > ---
> > 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 *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 = 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 |= (GPIOLINE_FLAG_OPEN_SOURCE |
> > GPIOLINE_FLAG_IS_OUT);
> > + if (test_bit(FLAG_PULL_DOWN, &desc->flags))
> > + lineinfo.flags |= GPIOLINE_FLAG_PULL_DOWN;
> > + if (test_bit(FLAG_PULL_UP, &desc->flags))
> > + lineinfo.flags |= 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 = 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/82fc38f6ab599ee03f7a8ed078de8abb41e6e611
> Cheers,
> Kent.
next prev parent reply other threads:[~2019-10-08 20:56 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-21 10:25 [RFC] gpio: expose pull-up/pull-down line flags to userspace Drew Fustini
2019-09-23 8:38 ` Bartosz Golaszewski
2019-10-02 11:10 ` Drew Fustini
2019-10-03 12:47 ` Linus Walleij
2019-10-04 7:22 ` Bartosz Golaszewski
2019-10-04 12:46 ` Bartosz Golaszewski
2019-10-05 17:02 ` Linus Walleij
2019-10-06 3:12 ` Kent Gibson
2019-10-06 21:06 ` Linus Walleij
2019-10-07 4:37 ` Kent Gibson
2019-10-08 6:15 ` Kent Gibson
2019-10-08 20:56 ` Bartosz Golaszewski [this message]
2019-10-08 23:21 ` Kent Gibson
2019-10-08 23:30 ` Bartosz Golaszewski
2019-10-08 23:56 ` Kent Gibson
2019-10-09 0:03 ` Bartosz Golaszewski
2019-10-09 0:22 ` Kent Gibson
2019-10-09 6:55 ` Kent Gibson
2019-10-09 12:57 ` Drew Fustini
2019-10-09 13:23 ` Kent Gibson
2019-10-09 13:30 ` Drew Fustini
2019-10-09 14:11 ` Kent Gibson
2019-10-09 15:50 ` Bartosz Golaszewski
2019-10-09 16:19 ` Kent Gibson
2019-10-09 23:59 ` Kent Gibson
2019-10-10 7:47 ` Drew Fustini
2019-10-10 10:14 ` Kent Gibson
2019-10-10 11:17 ` Kent Gibson
2019-10-11 13:04 ` Drew Fustini
2019-10-11 13:06 ` Drew Fustini
2019-10-11 13:49 ` Kent Gibson
2019-10-09 11:32 ` Drew Fustini
2019-10-09 13:57 ` Drew Fustini
2019-10-09 14:01 ` Kent Gibson
2019-10-09 11:46 ` Drew Fustini
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