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path: root/Documentation/gpio/driver.txt
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2016-09-23gpiolib: Make it possible to exclude GPIOs from IRQ domainMika Westerberg
When using GPIO irqchip helpers to setup irqchip for a gpiolib based driver, it is not possible to select which GPIOs to add to the IRQ domain. Instead it just adds all GPIOs which is not always desired. For example there might be GPIOs that for some reason cannot generated normal interrupts at all. To support this we add a flag irq_need_valid_mask to struct gpio_chip. When this flag is set the core allocates irq_valid_mask that holds one bit for each GPIO the chip has. By default all bits are set but drivers can manipulate this using set_bit() and clear_bit() accordingly. Then when gpiochip_irqchip_add() is called, this mask is checked and all GPIOs with bit is set are added to the IRQ domain created for the GPIO chip. Suggested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-04-27gpio: clarify open drain/source docsLinus Walleij
Make the text clearer, remove reference to confusing "positive" and "negative" and elaborate a bit. Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-04-09gpio: document open drain/source behaviourLinus Walleij
This has been a totally undocumented feature for years so add some generic concepts and documentation about open drain/source, include some facts on how we now support for hardware. Cc: Michael Hennerich <michael.hennerich@analog.com> Cc: Nicolas Saenz Julienne <nicolassaenzj@gmail.com> Cc: H. Nikolaus Schaller <hns@goldelico.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-11-20Doc: gpio: Fix typos in Documentation/gpioMasanari Iida
This patch fix some spelling typos found in Documentation/gpio. Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2015-10-27gpio: add a real time compliance notesGrygorii Strashko
Put in a compliance checklist. Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-10-27Revert "gpio: add a real time compliance checklist"Linus Walleij
This reverts commit 677b2ff4afd9996eabefc9472c701211b4b49e87.
2015-10-20gpio: add a real time compliance checklistLinus Walleij
Add some information about real time compliance to the driver document. Inspired by Grygorii Strashko's real time compliance patches. Cc: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-10-28gpio: rename gpio_lock_as_irq to gpiochip_lock_as_irqAlexandre Courbot
This function actually operates on a gpio_chip, so its prefix should reflect that fact for consistency with other functions defined in gpio/driver.h. Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-09-26gpio: handle also nested irqchips in the chained handler set-upLinus Walleij
To unify how we connect cascaded IRQ chips to parent IRQs, if NULL us passed as handler to the gpiochip_set_chained_irqchip() function, assume the chips is nested rather than chained, and we still get the parent set up correctly by way of this function call. Alter the drivers for tc3589x and stmpe to use this to set up their chained handlers as a demonstration of the usage. Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-08-29gpio: change gpiochip_request_own_desc() prototypeAlexandre Courbot
The current prototype of gpiochip_request_own_desc() requires to obtain a pointer to a descriptor. This is in contradiction to all other GPIO request schemes, and imposes an extra step of obtaining a descriptor to drivers. Most drivers actually cannot even perform that step since the function that does it (gpichip_get_desc()) is gpiolib-private. Change gpiochip_request_own_desc() to return a descriptor from a (chip, hwnum) tuple and update users of this function (currently gpiolib-acpi only). Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-07-24gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_descGuenter Roeck
Both functions were introduced to let gpio drivers request their own gpio pins. Without exporting the functions, this can however only be used by gpio drivers built into the kernel. Secondary impact is that the functions can not currently be used by platform initialization code associated with the gpio-pca953x driver. This code permits auto-export of gpio pins through platform data, but if this functionality is used, the module can no longer be unloaded due to the problem solved with the introduction of gpiochip_request_own_desc and gpiochip_free_own_desc. Export both function so they can be used from modules and from platform initialization code. Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-07-23gpio: remove gpiod_lock/unlock_as_irq()Alexandre Courbot
gpio_lock/unlock_as_irq() are working with (chip, offset) arguments and are thus not using the old integer namespace. Therefore, there is no reason to have gpiod variants of these functions working with descriptors, especially since the (chip, offset) tuple is more suitable to the users of these functions (GPIO drivers, whereas GPIO descriptors are targeted at GPIO consumers). Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-04-28gpio: document gpio irqchips a bit more, describe helpersLinus Walleij
This adds some documentation about the GPIO irqchips, what types exist etc. Acked-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-02-03gpio: document how to make combined GPIO+irqchip driversLinus Walleij
Write a few words on how GPIO drivers supplying an irqchip should be written. Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2013-11-25Documentation: gpiolib: document new interfaceAlexandre Courbot
gpiolib now exports a new descriptor-based interface which deprecates the older integer-based one. This patch documents this new interface and also takes the opportunity to brush-up the GPIO documentation a little bit. The new descriptor-based interface follows the same consumer/driver model as many other kernel subsystems (e.g. clock, regulator), so its documentation has similarly been splitted into different files. The content of the former documentation has been reused whenever it made sense; however, some of its content did not apply to the new interface anymore and have this been removed. Likewise, new sections like the mapping of GPIOs to devices have been written from scratch. The deprecated legacy-based documentation is still available, untouched, under Documentation/gpio/gpio-legacy.txt. Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>