Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 17 Mar 2020 12:32:31 +0100 | Subject | Re: [PATCH v5 3/5] gpio: Add GPIO Aggregator |
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On Tue, Feb 18, 2020 at 4:18 PM Geert Uytterhoeven <geert+renesas@glider.be> wrote: > GPIO controllers are exported to userspace using /dev/gpiochip* > character devices. Access control to these devices is provided by > standard UNIX file system permissions, on an all-or-nothing basis: > either a GPIO controller is accessible for a user, or it is not. > Currently no mechanism exists to control access to individual GPIOs. > > Hence add a GPIO driver to aggregate existing GPIOs, and expose them as > a new gpiochip. > > This supports the following use cases: > - Aggregating GPIOs using Sysfs > This is useful for implementing access control, and assigning a set > of GPIOs to a specific user or virtual machine. > - Generic GPIO Driver > This is useful for industrial control, where it can provide > userspace access to a simple GPIO-operated device described in DT, > cfr. e.g. spidev for SPI-operated devices. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> --- /dev/null > +++ b/drivers/gpio/gpio-aggregator.c
> +static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset, > + unsigned long config) > +{ > + struct gpiochip_fwd *fwd = gpiochip_get_data(chip); > + > + chip = fwd->descs[offset]->gdev->chip; > + if (chip->set_config)
- chip = fwd->descs[offset]->gdev->chip; - if (chip->set_config) + chip = gpiod_to_chip(fwd->descs[offset]); + if (chip && chip->set_config)
> + return chip->set_config(chip, offset, config);
This is not correct: offset should be translated, too, i.e.
offset = gpio_chip_hwgpio(fwd->descs[offset]);
Which adds a new dependency on "gpiolib.h"...
Is there a better alternative, than providing a public gpiod_set_config() helper? Thanks!
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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