On Fri, Dec 4, 2015 at 6:31 PM, Martyn Welch <martyn.welch@xxxxxxxxxxxxxxx> wrote: > Select Chromebooks have gpio attached to switches used to cause the > firmware to enter alternative modes of operation and/or control other > device characteristics (such as write protection on flash devices). This > patch adds a driver that exposes a read-only interface to allow these > signals to be read from user space. > > This functionality has been generalised to provide support for any device > with device tree support which needs to identify a gpio as being used for a > specific task. > > Signed-off-by: Martyn Welch <martyn.welch@xxxxxxxxxxxxxxx> If you want to do this thing, also propose a device tree binding document for "gpio-switch". But first (from Documentation/gpio/drivers-on-gpio.txt): - gpio-keys: drivers/input/keyboard/gpio_keys.c is used when your GPIO line can generate interrupts in response to a key press. Also supports debounce. - gpio-keys-polled: drivers/input/keyboard/gpio_keys_polled.c is used when your GPIO line cannot generate interrupts, so it needs to be periodically polled by a timer. - extcon-gpio: drivers/extcon/extcon-gpio.c is used when you need to read an external connector status, such as a headset line for an audio driver or an HDMI connector. It will provide a better userspace sysfs interface than GPIO. So you mean none of these apply for this case? Second: what you want to do is export a number of GPIOs with certain names to userspace. This is something very generic and should be implemented as such, not as something Chromebook-specific. Patches like that has however already been suggested, and I have NACKed them because the GPIO sysfs ABI is insane, and that is why I am refactoring the world to create a proper chardev ABI for GPIO instead. See: http://marc.info/?l=linux-gpio&m=144550276512673&w=2 So for the moment, NACK on this, please participate in creating the *right* ABI for GPIO instead of trying to shoehorn stuff into the dying sysfs ABI. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
