• Linus Walleij's avatar
    gpio: add userspace ABI for GPIO line information · 521a2ad6
    Linus Walleij authored
    This adds a GPIO line ABI for getting name, label and a few select
    flags from the kernel.
    
    This hides the kernel internals and only tells userspace what it
    may need to know: the different in-kernel consumers are masked
    behind the flag "kernel" and that is all userspace needs to know.
    
    However electric characteristics like active low, open drain etc
    are reflected to userspace, as this is important information.
    
    We provide information on all lines on all chips, later on we will
    likely add a flag for the chardev consumer so we can filter and
    display only the lines userspace actually uses in e.g. lsgpio,
    but then we first need an ABI for userspace to grab and use
    (get/set/select direction) a GPIO line.
    
    Sample output from "lsgpio" on ux500:
    
    GPIO chip: gpiochip7, "8011e000.gpio", 32 GPIO lines
            line 0: unnamed unlabeled
            line 1: unnamed unlabeled
    (...)
            line 25: unnamed "SFH7741 Proximity Sensor" [kernel output open-drain]
            line 26: unnamed unlabeled
    (...)
    Tested-by: default avatarMichael Welling <mwelling@ieee.org>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    521a2ad6
lsgpio.c 3.68 KB