From: Michael Welling <mwelling@ieee.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org,
Alexandre Courbot <acourbot@nvidia.com>,
Johan Hovold <johan@kernel.org>,
Markus Pargmann <mpa@pengutronix.de>,
Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>,
Grant Likely <grant.likely@linaro.org>
Subject: Re: [PATCH v2] gpio: add userspace ABI for GPIO line information
Date: Tue, 16 Feb 2016 12:28:59 -0600 [thread overview]
Message-ID: <20160216182859.GA15568@deathstar> (raw)
In-Reply-To: <1455542435-3182-1-git-send-email-linus.walleij@linaro.org>
On Mon, Feb 15, 2016 at 02:20:35PM +0100, Linus Walleij wrote:
> This adds a GPIO line ABI for getting name, label and a few select
> flags from the kernel.
>
> This hides the kernel internals and only tells userspace what it
> may need to know: the different in-kernel consumers are masked
> behind the flag "kernel" and that is all userspace needs to know.
>
> However electric characteristics like active low, open drain etc
> are reflected to userspace, as this is important information.
>
> We provide information on all lines on all chips, later on we will
> likely add a flag for the chardev consumer so we can filter and
> display only the lines userspace actually uses in e.g. lsgpio,
> but then we first need an ABI for userspace to grab and use
> (get/set/select direction) a GPIO line.
>
> Sample output from "lsgpio" on ux500:
>
> GPIO chip: gpiochip7, "8011e000.gpio", 32 GPIO lines
> line 0: unnamed unlabeled
> line 1: unnamed unlabeled
> (...)
> line 25: unnamed "SFH7741 Proximity Sensor" [kernel output open-drain]
> line 26: unnamed unlabeled
> (...)
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
I attempted to test the gpio char implementation on the Dragonboard 410c and it
fails to boot.
I just pulled the linux-gpio/chardev-more branch and built from there. The board
boots from the mainline 4.5-rc2.
If there were any boot messages I would give them to you but it fails early.
Tried to get more from earlycon but still nothing.
Do you have a 64 bit arm target to test this on to see if it fails for you as
well?
next prev parent reply other threads:[~2016-02-16 18:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-15 13:20 [PATCH v2] gpio: add userspace ABI for GPIO line information Linus Walleij
2016-02-16 18:28 ` Michael Welling [this message]
2016-02-17 20:54 ` Michael Welling
2016-02-19 8:55 ` Linus Walleij
2016-02-19 9:46 ` Michael Welling
2016-02-19 9:47 ` Linus Walleij
2016-02-19 10:26 ` Michael Welling
2016-02-19 11:25 ` Linus Walleij
2016-02-19 11:29 ` Grant Likely
2016-02-19 11:54 ` Linus Walleij
2016-02-19 11:35 ` jic23
2016-02-19 11:51 ` Linus Walleij
2016-02-21 13:13 ` Markus Pargmann
2016-02-21 19:04 ` Linus Walleij
2016-02-22 12:05 ` Markus Pargmann
2016-02-22 12:25 ` Linus Walleij
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