Re: sysfs: wait for GPIO interrupt

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Wed, May 14, 2014 at 11:32 AM, Javier Martinez Canillas
<javier@xxxxxxxxxxxx> wrote:

> I was wondering the same. Unfortunately writing a small device driver
> that uses gpiolib from the kernel is sometimes not possible for many
> companies.

This is one of the promises of device tree. Certainly customers of
a Linux BSP can make device trees.

So for a heartbeat LED on some GPIO for example, compile
in the necessary LED and trigger modules and:

        leds {
                compatible = "gpio-leds";
                used-led {
                        label = "user_led";
                        gpios = <&gpio4 14 0x4>;
                        default-state = "on";
                        linux,default-trigger = "heartbeat";
                };
        };

Simple key input:

        gpio_keys {
                compatible = "gpio-keys";
                #address-cells = <1>;
                #size-cells = <0>;

                button@1 {
                        debounce_interval = <50>;
                        wakeup = <1>;
                        linux,code = <2>;
                        label = "userpb";
                        gpios = <&gpio1 0 0x4>;
                };
       };

We need to enable users to use such stock items, not
teach them to shoot themselves in the foot in userspace.

Yours,
Linus Walleij
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