Re: pinctrl-single: num_maps in generic pinconf support?

[Drew Fustini <drew@beagleboard.org>]

On Mon, Jun 08, 2020 at 08:05:43PM +0200, Drew Fustini wrote:
> On Fri, May 29, 2020 at 10:40:37AM -0700, Tony Lindgren wrote:
> > * Drew Fustini <drew@beagleboard.org> [200528 12:54]:
> > > Would you be able to describe what you think AM33XX_PADCONF would look
> > > like if the mux and conf are seperated?
> > 
> > Yes it would just slightly change, see your example below.
> > 
> > > Is there an example you know of for another SoC?
> > 
> > I think the other driver already keep the padconf and mux separate.
> > 
> > So not sure where all #pinctrl-cells could be used. It would make
> > pinctrl-single.c a bit nicer though, and probably would make it
> > easier to implement further features.
> > 
> > Some hardware may need it to have #pinctrl-cells = <3> if GPIO
> > features are there too, ideally pinctrl-single would not even
> > care but just work for what is configured for the hardware.
> > 
> > > Currently, the macro takes dir and mux:
> > > 
> > > include/dt-bindings/pinctrl/omap.h:
> > > #define AM33XX_PADCONF(pa, dir, mux) OMAP_IOPAD_OFFSET((pa), 0x0800) ((dir) | (mux))
> > 
> > So after fixing up pinctrl-single.c, and changing the SoC dts
> > to have #pinctrl-cells = <2> instead of <1>, the macro would
> > then need to be:
> > 
> > #define AM33XX_PADCONF(pa, dir, mux) OMAP_IOPAD_OFFSET((pa), 0x0800) (dir), (mux))
> > 
> > > For example, in arch/arm/boot/dts/am335x-bone-common.dtsi:
> > > AM33XX_PADCONF(AM335X_PIN_I2C0_SDA, PIN_INPUT_PULLUP, MUX_MODE0)
> > 
> > Yeah so no change needed for the use.
> > 
> > > I think it might be more accurate to rename 'dir' to 'conf'.
> > 
> > Sure makes sense to rename it in the macro.
> > 
> > Regards,
> > 
> > Tony
> 
> Tony - would this be how the macro would need to be changed?
> 
> diff --git a/include/dt-bindings/pinctrl/omap.h b/include/dt-bindings/pinctrl/omap.h
> index 625718042413..2d2a8c737822 100644
> --- a/include/dt-bindings/pinctrl/omap.h
> +++ b/include/dt-bindings/pinctrl/omap.h
> @@ -65,7 +65,7 @@
>  #define DM814X_IOPAD(pa, val)          OMAP_IOPAD_OFFSET((pa), 0x0800) (val)
>  #define DM816X_IOPAD(pa, val)          OMAP_IOPAD_OFFSET((pa), 0x0800) (val)
>  #define AM33XX_IOPAD(pa, val)          OMAP_IOPAD_OFFSET((pa), 0x0800) (val)
> -#define AM33XX_PADCONF(pa, dir, mux)   OMAP_IOPAD_OFFSET((pa), 0x0800) ((dir) | (mux))
> +#define AM33XX_PADCONF(pa, conf, mux)  OMAP_IOPAD_OFFSET((pa), 0x0800) (conf) (mux)
> 
>  /*
>   * Macros to allow using the offset from the padconf physical address

I've been looking at pinctrl-single.c further and now I am wondering if
it makes sense to modify pcs_parse_one_pinctrl_entry() or create a new
function.  Currently it does:

1020                 /* Index plus one value cell */
1021                 offset = pinctrl_spec.args[0];
1022                 vals[found].reg = pcs->base + offset;
1023                 vals[found].val = pinctrl_spec.args[1];

I believe it will need something similar to what is done in
pcs_parse_bits_in_pinctrl_entry():

1136                 /* Index plus two value cells */
1137                 offset = pinctrl_spec.args[0];
1138                 val = pinctrl_spec.args[1];
1139                 mask = pinctrl_spec.args[2];

So using #pinctrl-cells = <2> would require would require:

offset = pinctrl_spec.args[0];
vals[found].reg = pcs->base + offset;
vals[found].conf = pinctrl_spec.args[1];
vals[found].mux = pinctrl_spec.args[2];

However, the type of vals:

struct pcs_func_vals {
	void __iomem *reg;
	unsigned val;
	unsigned mask;
};

represents the combined mux + conf value in the register, so I think
pcs_conf_vals would need to used:

struct pcs_conf_vals {
	enum pin_config_param param;
	unsigned val;
	unsigned enable;
	unsigned disable;
	unsigned mask;
};

Thoughts?

thanks,
drew