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path: root/Documentation/acpi/gpio-properties.txt
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2017-05-29gpio: acpi: Explain how to get GPIO descriptors in ACPI caseAndy Shevchenko
Documentation lacks of explanation how we actually use device properties for GPIO resources. Add a section to the documentation about that. Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-24ACPI / gpio: Add support for naming GPIOsMika Westerberg
Now that we have the new helper function that sets nice names for GPIO lines based on "gpio-line-names" device property, we can take advantage of this in acpi_gpiochip_add(). Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-24ACPI / gpio: Add hogging supportMika Westerberg
GPIO hogging means that the GPIO controller can "hog" and configure certain GPIOs without need for a driver or userspace to do that. This is useful in open-connected boards where BIOS cannot possibly know beforehand which devices will be connected to the board. This adds GPIO hogging mechanism to ACPI analogous to Device Tree. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-24ACPI / gpio: Allow holes in list of GPIOs for a deviceMika Westerberg
Make it possible to have an empty GPIOs in a GPIO list for device. For example a SPI master may use both GPIOs and native pins as chip selects and we need to be able to distinguish between the two. This makes it mandatory to have exactly 3 arguments for GPIOs and then converts gpiolib to use of __acpi_node_get_property_reference() instead. In addition we make acpi_gpio_package_count() to handle holes as well (this matches the DT version). Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-09-29ACPI / documentation: Use recommended name in GPIO property namesMika Westerberg
The recommended property name for all kinds of GPIOs is to end it with "-gpios" even if there is only one GPIO. Update the documentation to follow this fact. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-04ACPI / documentation: Fix ambiguity in the GPIO properties documentRafael J. Wysocki
The first paragraph in Documentation/acpi/gpio-properties.txt is ambiguous, so make it more clear. Reported-by: Antonio Ospite <ao2@ao2.it> Acked-by: Antonio Ospite <ao2@ao2.it> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-11-04ACPI / GPIO: Document ACPI GPIO mappings APIRafael J. Wysocki
Document the previously introduced method that can be used by device drivers to provide the GPIO subsystem with mappings between GPIO names (connection IDs) and GpioIo()/GpioInt() resources in _CRS. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
2014-11-04gpio / ACPI: Add support for _DSD device propertiesMika Westerberg
With release of ACPI 5.1 and _DSD method we can finally name GPIOs (and other things as well) returned by _CRS. Previously we were only able to use integer index to find the corresponding GPIO, which is pretty error prone if the order changes. With _DSD we can now query GPIOs using name instead of an integer index, like the below example shows: // Bluetooth device with reset and shutdown GPIOs Device (BTH) { Name (_HID, ...) Name (_CRS, ResourceTemplate () { GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, "\\_SB.GPO0", 0, ResourceConsumer) {15} GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, "\\_SB.GPO0", 0, ResourceConsumer) {27, 31} }) Name (_DSD, Package () { ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), Package () { Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }}, Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }}, } }) } The format of the supported GPIO property is: Package () { "name", Package () { ref, index, pin, active_low }} ref - The device that has _CRS containing GpioIo()/GpioInt() resources, typically this is the device itself (BTH in our case). index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero. pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero. active_low - If 1 the GPIO is marked as active_low. Since ACPI GpioIo() resource does not have field saying whether it is active low or high, the "active_low" argument can be used here. Setting it to 1 marks the GPIO as active low. In our Bluetooth example the "reset-gpio" refers to the second GpioIo() resource, second pin in that resource with the GPIO number of 31. This patch implements necessary support to gpiolib for extracting GPIOs using _DSD device properties. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Grant Likely <grant.likely@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>