dt-bindings: gpio.txt: expand gpio-line-names recommendations

Provide more guidance to differentiate between recommendations for names of
lines which are hard-wired to on-board devices, versus recommendations for
names of lines which are connected to general-purpose pin headers.

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

dt-bindings: gpio: fix gpio-hog example

Even if this is no yaml yet at least fix the example to be compliant to
later schema as e.g. found in gpio-pca95xx.yaml, fairchild,74hc595.yaml
and gpio/fsl-imx-gpio.yaml.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

dt-bindings: gpio: document the new pull-up/pull-down flags

This commit extends the flags that can be used in GPIO specifiers to
indicate if a pull-up resistor or pull-down resistor should be
enabled.

While some pinctrl DT bindings already offer the capability of
configuring pull-up/pull-down resistors at the pin level, a number of
simple GPIO controllers don't have any pinmuxing capability, and
therefore do not rely on the pinctrl DT bindings.

Such simple GPIO controllers however sometimes allow to configure
pull-up and pull-down resistors on a per-pin basis, and whether such
resistors should be enabled or not is a highly board-specific HW
characteristic.

By using two additional bits of the GPIO flag specifier, we can easily
allow the Device Tree to describe which GPIOs should have their
pull-up or pull-down resistors enabled. Even though the two options
are mutually exclusive, we still need two bits to encode at least
three states: no pull-up/pull-down, pull-up, pull-down.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: OF: Remove bad practice examples

We remove the references to anything but two-cell GPIO specifiers
and just mention that controllers need to specify their bindings
and that we strongly recommend two-cell bindings.

Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: OF: Cut painful BNF experiments from bindings

In 2011 the commit bf859f84a19f
("gpio/dt: Refine GPIO device tree binding") introduced an
experimental BNF notation for defining a regular grammar for
the GPIO phandles used by different devices.

This was an interesting approach, and shows that we have long
nutured the idea to formally verify device tree files using
regular grammar.

Most if not all other bindings use natural language to define
the bindings, and the recent thinking for verifying device
tree files is to use JSON schemas in separate definitions.

Cut the BNF business and replace it with natural language
so that it becomes more human-readable for now.

Cc: devicetree@vger.kernel.org
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Kumar Gala <galak@kernel.crashing.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: of: make example syntactically correct

The ';' was missing. And cosmetic: there was a space too much.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

dt-bindings: gpio: Add a gpio-reserved-ranges property

Some qcom platforms make some GPIOs or pins unavailable for use
by non-secure operating systems, and thus reading or writing the
registers for those pins will cause access control issues.
Introduce a DT property to describe the set of GPIOs that are
available for use so that higher level OSes are able to know what
pins to avoid reading/writing.

Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: <devicetree@vger.kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

dt-bindings: Use lower case hex in unit-addresses

DT unit addresses should be lower case hex. Fix all the
binding examples.

Converted with the following command from Krzysztof Kozlowski:

sed -e 's/@\([a-fA-F0-9_-]*\) {/@\L\1 {/' -i $(find Documentation/devicetree/bindings -name '*.txt')

Signed-off-by: Rob Herring <robh@kernel.org>

gpio: of: Add documentation of new sleep standard GPIO specifiers

Add documentation of new GPIO specifiers indicating if the state of an
output pin should be maintained during sleep/low-power mode.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: of: Reflect decoupling of open collector and active low/high

Commit 4c0facddb7d8 ("gpio: core: Decouple open drain/source flag with
active low/high") decoupled the open collector outputs from active
low/high but did not update the documentation.

Update the device tree documentation to correctly reflect this new
separation between the two concepts.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: fix description for gpio-ranges example

The length of the second entry is 20, so it affects GPIOs 10..29.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: of: Add support for multiple GPIOs in a single GPIO hog

When listing multiple GPIOs in the "gpios" property of a GPIO hog, only
the first GPIO is affected. The user is left clueless about the
dysfunctioning of the other GPIOs specified.

Fix this by adding and documenting support for specifying multiple
GPIOs in a single GPIO hog.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: of: make it possible to name GPIO lines

Make it possible to name the producer side of a GPIO line using
a "gpio-line-names" property array, modeled on the
"clock-output-names" property from the clock bindings.

This naming is especially useful for:

- Debugging: lines are named after function, not just opaque
offset numbers.

- Exploration: systems where some or all GPIO lines are available
to end users, such as prototyping, one-off's "makerspace usecases"
users are helped by the names of the GPIO lines when tinkering.
This usecase has been surfacing recently.

The gpio-line-names attribute is completely optional.

Example output from lsgpio on a patched Snowball tree:

GPIO chip: gpiochip6, "8000e180.gpio", 32 GPIO lines
line 0: unnamed unused
line 1: "AP_GPIO161" "extkb3" [kernel]
line 2: "AP_GPIO162" "extkb4" [kernel]
line 3: "ACCELEROMETER_INT1_RDY" unused [kernel]
line 4: "ACCELEROMETER_INT2" unused
line 5: "MAG_DRDY" unused [kernel]
line 6: "GYRO_DRDY" unused [kernel]
line 7: "RSTn_MLC" unused
line 8: "RSTn_SLC" unused
line 9: "GYRO_INT" unused
line 10: "UART_WAKE" unused
line 11: "GBF_RESET" unused
line 12: unnamed unused

Cc: Grant Likely <grant.likely@linaro.org>
Cc: Amit Kucheria <amit.kucheria@linaro.org>
Cc: David Mandala <david.mandala@linaro.org>
Cc: Lee Campbell <leecam@google.com>
Cc: devicetree@vger.kernel.org
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: revert bank bindings

Keep the words talking about what a GPIO bank is, but remove the
binding. We have not agreed that this is something we want to have.

Acked-by: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: dt-bindings: document the concept of GPIO banks

Cc: devicetree@vger.kernel.org
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: dt-bindings: document the official use of "ngpios"

There are a bunch of drivers that utilize the "ngpios" DT property
without any vendor prefix. Try to start cleaning up the mess by
defining what we mean by this property.

Cc: devicetree@vger.kernel.org
Cc: Pramod Kumar <pramodku@broadcom.com>
Cc: Jonas Gorski <jogo@openwrt.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: add DT bindings for existing consumer flags

It is customary for GPIO controllers to support open drain/collector
and open source/emitter configurations. Add standard GPIO line flags
to account for this and augment the documentation to say that these
are the most generic bindings.

Several people approached me to add new flags to the lines, and this
makes sense, but let's first bind up the most common cases before we
start to add exotic stuff.

Thanks to H. Nikolaus Schaller for ideas on how to encode single-ended
wiring such as open drain/source and open collector/emitter.

Cc: Tony Lindgren <tony@atomide.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: mention in DT binding doc that <name>-gpio is deprecated

The gpiolib supports parsing DT properties of the form <name>-gpio but it
was only added for compatibility with older DT bindings that got it wrong
and should not be used in newer bindings.

The commit that added support for this was:

dd34c37aa3e8 ("gpio: of: Allow -gpio suffix for property names")

but didn't update the documentation to explain this so it's been a source
of confusion. So let's make this clear in the GPIO DT binding doc.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Rob Herring <robh@kernel.org>

gpio: Document GPIO hogging mechanism

Add GPIO hogging documentation to gpio.txt

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation: gpio: fix bindings document

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation: gpio: guidelines for bindings

Now that ACPI supports named GPIO properties, either through ACPI 5.1 or
the per-driver ACPI GPIO mappings, we can be more narrow about the way
GPIOs should be specified in Device Tree bindings.

This patch updates the GPIO DT bindings documentation to highlight the
following rules for new GPIO bindings:

- All new bindings must have a meaningful name (e.g. the "gpios"
property must not be used)
- The only suffix allowed is "-gpios", no matter the number of
descriptors in the property
- GPIOs can only be grouped under the same property when they serve the
same purpose, a case that should remain exceptional (e.g. bit-banged
data lines).

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: document polarity flag best practices

Document what we (Laurent and I, following a mailing list dicussion)
believe are best practices for the polarity flag in a GPIO specifier.

While touching the doc, I made a few minor editing changes to other
areas.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl/gpio: non-linear GPIO ranges accesible from gpiolib

This patch adds the infrastructure required to register non-linear gpio
ranges through gpiolib and the standard GPIO device tree bindings.

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: clean up gpio-ranges documentation

This change makes documentation of the the gpio-ranges property shorter
and more succinct, more consistent with the style of the rest of the
document, and not mention Linux-specifics such as the API
pinctrl_request_gpio(); DT binding documents should be OS independant
where at all possible. As part of this, the gpio-ranges property's format
is described in BNF form, in order to match the rest of the document.

This change also deprecates the #gpio-range-cells property. Such
properties are useful when one node references a second node, and that
second node dictates the format of the reference. However, that is not
the case here; the definition of gpio-ranges itself always dictates its
format entirely, and hence the value #gpio-range-cells must always be 3,
and hence there is no point requiring any referenced node to include
this property. The only remaining need for this property is to ensure
compatibility of DTs with older SW that was written to support the
previous version of the binding.

v4:
* Mention #gpio-range-cells as being deprecated, rather than removing all
documentation of that property. This allows DTs to be written in a
backwards-compatible way if desired, and also allows older DTs to be
interpreted fully using the latest documentation.
v3:
* Mention BNF in commit description.
* Fixed typo.
* Dropped patch that removed the deprecated property from *.dts, since
it's required to boot older kernels.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio: add gpio offset in gpio range cells property

Add gpio offset into "gpio-range-cells" property. It's used to support
sparse pinctrl range in gpio chip.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpiolib: provide provision to register pin ranges

pinctrl subsystem needs gpio chip base to prepare set of gpio
pin ranges, which a given pinctrl driver can handle. This is
important to handle pinctrl gpio request calls in order to
program a given pin properly for gpio operation.

As gpio base is allocated dynamically during gpiochip
registration, presently there exists no clean way to pass this
information to the pinctrl subsystem.

After few discussions from [1], it was concluded that may be
gpio controller reporting the pin range it supports, is a
better way than pinctrl subsystem directly registering it.

[1] http://comments.gmane.org/gmane.linux.ports.arm.kernel/184816

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
[Edited documentation a bit]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

gpio/dt: Refine GPIO device tree binding

Allow for multiple named gpio properties

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

dt: Move device tree documentation out of powerpc directory

The device tree is used by more than just PowerPC. Make the documentation
directory available to all.

v2: reorganized files while moving to create arch and driver specific
directories.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>