[PATCH 1/4 v4] drivers: create a pin control subsystem

Linus Walleij linus.walleij at linaro.org
Mon Aug 22 12:38:16 UTC 2011

On Sun, Aug 21, 2011 at 4:24 PM, Jamie Iles <jamie at jamieiles.com> wrote:

> for device tree, when the gpio
> controllers are registered, the base is typically dynamically assigned.  I
> suspect that this can be solved in the device tree binding for the controller
> that references the bindings of the pinctrl, but this would require
> registering the gpio_ranges at runtime (or at least the bases).

Oh registering ranges at runtime ... crap. But possible I think.

> So perhaps if we had:
> struct pinctrl_gpio_range {
>    unsigned int pinctrl_base;
>    struct gpio_chip *chip;
> }
> and then gpio_request_enable was:
> int (*gpio_request_enable)(struct pinctrl_dev *pctldev,
>                           struct gpio_chip *gc,
>                           unsigned offset)
> Then have pinctrl_register_gpio_chip()?

I'm not following - the struct gpio_chip is opaque outside the gpio
subsystem, I've proposed patches to make it public but they have
been NAK:ed.

Which means pinctrl has no use of that pointer.

What is the intended purpose of sending that thing in?

Right now my range struct looks like this:

 * struct pinctrl_gpio_range - each pin controller can provide subranges of
 * the GPIO number space to be handled by the controller
 * @name: a name for the chip in this range
 * @id: an ID number for the chip in this range
 * @base: base offset of the GPIO range
 * @npins: number of pins in the GPIO range, including the base number
struct pinctrl_gpio_range {
        const char name[16];
        unsigned int id;
        unsigned int base;
        unsigned int npins;

> For the static devices case then we can require gc->base must match the
> pinctrl gpio base. For the device tree case we could do some matching of
> device_nodes from the gpio_chip to the pinctrl definitions?

Can't do that since we can't look into struct gpio_chip intrinsics...

But we can register ranges at runtime, I'll just make the pin controller keep
a list of GPIO ranges, simple.

Linus Walleij

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