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2014-10-30Documentation: gpio: guidelines for bindingsAlexandre Courbot1-14/+26
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>
2014-02-27gpio: document polarity flag best practicesStephen Warren1-8/+52
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>
2013-10-16pinctrl/gpio: non-linear GPIO ranges accesible from gpiolibChristian Ruppert1-2/+38
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>
2013-08-15gpio: clean up gpio-ranges documentationStephen Warren1-25/+30
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>
2013-03-07gpio: add gpio offset in gpio range cells propertyHaojian Zhuang1-3/+3
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>
2012-11-11gpiolib: provide provision to register pin rangesShiraz Hashim1-0/+36
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>
2011-06-28gpio/dt: Refine GPIO device tree bindingGrant Likely1-9/+37
Allow for multiple named gpio properties Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-01-31dt: Move device tree documentation out of powerpc directoryGrant Likely1-0/+50
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>