Hi Linus,
On Fri, Aug 19, 2011 at 03:26:08PM +0100, Jamie Iles wrote:
> On Fri, Aug 19, 2011 at 04:04:54PM +0200, Linus Walleij wrote:
> > On Fri, Aug 19, 2011 at 12:48 PM, Jamie Iles <ja...@jamieiles.com> wrote:
[...]
> > But yes, there is an assumption that each pin controller will only
> > deal with one block of GPIO pins. So if I make it possible to support
> > several GPIO ranges for one pin controller, does that solve your problem?
> >
> > Like this:
> >
> > struct pinctrl_gpio_range {
> > char *name;
> > unsigned int base;
> > unsigned int npins;
> > }
> >
> > static unsigned int gpio_ranges[] = {
> > {
> > .name="chip1",
> > .base = 0,
> > .npins = 16,
> > },
> > {
> > .name =" chip2",
> > .base = 32,
> > .npins = 16,
> > },
> > {
> > .name = "chip3",
> > .base = 64,
> > .npins = 16,
> > },
> > };
> >
> > static struct pinctrl_desc foo_desc = {
> > ...
> > .gpio_ranges = gpio_ranges,
> > .num_gpio_ranges = ARRAY_SIZE(gpio_ranges),
> > };
> >
> > For three different 32-bit GPIO controllers muxed on
> > pins 0..31 using GPIO space pins from 0..95.
> >
> > Then I pass the number of the instance down to the
> > driver in the gpio_request_enable() callback like
> > this:
> >
> > int (*gpio_request_enable) (struct pinctrl_dev *pctldev,
> > unsigned instance,
> > unsigned offset);
> >
> > Would this work?
> >
> > This has a restriction: the GPIO space must be mapped in
> > continous ranges, as must the pin controller. Else we need
> > one entry per pin in the list above...
One more thing that I thought of is that 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).
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()?
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?
Jamie
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