Re: [PATCH 4/6] pinctrl: intel: Add support for hardware debouncer

[Mika Westerberg]

On Thu, Jan 05, 2017 at 01:14:36AM +0200, Andy Shevchenko wrote:
> On Wed, Jan 4, 2017 at 5:31 PM, Mika Westerberg
> <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> > The next generation Intel GPIO hardware has two additional registers
> > PADCFG2 and PADCFG3. The latter is marked as reserved but the former
> > includes configuration for per-pad hardware debouncer.
> >
> > This patch adds support for that in the Intel pinctrl core driver. Since
> > these are additional features on top of the current generation hardware,
> > we use revision number and feature flags to enable this if detected.
> 
> Few comments below.
> 
> > @@ -244,6 +264,7 @@ static void intel_pin_dbg_show(struct pinctrl_dev *pctldev, struct seq_file *s,
> >                                unsigned pin)
> >  {
> >         struct intel_pinctrl *pctrl = pinctrl_dev_get_drvdata(pctldev);
> > +       void __iomem *padcfg;
> 
> Perhaps padcfg2 ?
> 
> I don't remember if we had such a pattern earlier in the code, though
> it would be better for my opinion to map local variable name to
> register name.
> 
> At least you are using it later here.

In this case, we expect to print out also padcfg3 when it gets some
functionality other than reserved. I'm going to use the same variable
for that as well then.

The comment where padcfg is used in the patch even says that:

/* Dump the additional PADCFG registers if available */

(registers, not register) ;-)

> 
> > @@ -552,6 +596,53 @@ static int intel_config_set_pull(struct intel_pinctrl *pctrl, unsigned pin,
> >         return ret;
> >  }
> >
> > +static int intel_config_set_debounce(struct intel_pinctrl *pctrl, unsigned pin,
> > +                                    unsigned debounce)
> > +{
> > +       void __iomem *padcfg0, *padcfg2;
> > +       unsigned long flags;
> > +       u32 value0, value2;
> > +       int ret = 0;
> > +
> > +       padcfg2 = intel_get_padcfg(pctrl, pin, PADCFG2);
> > +       if (!padcfg2)
> > +               return -ENOTSUPP;
> > +
> > +       padcfg0 = intel_get_padcfg(pctrl, pin, PADCFG0);
> > +
> > +       raw_spin_lock_irqsave(&pctrl->lock, flags);
> > +
> > +       value0 = readl(padcfg0);
> > +       value2 = readl(padcfg2);
> > +
> > +       /* Disable glitch filter and debouncer */
> > +       value0 &= ~PADCFG0_PREGFRXSEL;
> > +       value2 &= ~(PADCFG2_DEBEN | PADCFG2_DEBOUNCE_MASK);
> > +
> > +       if (debounce) {
> > +               unsigned long v;
> > +
> > +               v = order_base_2(debounce * 1000 / DEBOUNCE_PERIOD);
> 
> > +               if (v < 3 || v > 15) {
> > +                       ret = -EINVAL;
> > +               } else {
> > +                       /* Enable glitch filter and debouncer */
> > +                       value0 |= PADCFG0_PREGFRXSEL;
> > +                       value2 |= v << PADCFG2_DEBOUNCE_SHIFT;
> > +                       value2 |= PADCFG2_DEBEN;
> > +               }
> > +       }
> > +
> > +       if (!ret) {
> 
> Would be cleaner to
> if (ret)
>  goto exit_unlock;
> ...
> 
> > +               writel(value0, padcfg0);
> > +               writel(value2, padcfg2);
> > +       }
> > +
> 
> exit_unlock:
> 
> ?
> 
> Or even do this above
> 
> if (v < 3 || v > 15) {
>  ret = ...
>  goto exit_unlock;
> }

I agree. Will change it to use the latter.

> 
> > +       raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> > +
> > +       return ret;
> > +}
> 
> > @@ -1000,6 +1110,18 @@ int intel_pinctrl_probe(struct platform_device *pdev,
> >                 if (IS_ERR(regs))
> >                         return PTR_ERR(regs);
> >
> > +               /*
> > +                * Determine community features based on the revision if
> > +                * not specified already.
> > +                */
> > +               if (!community->features) {
> > +                       u32 rev;
> > +
> > +                       rev = (readl(regs + REVID) & REVID_MASK) >> REVID_SHIFT;
> > +                       if (rev >= 0x94)
> 
> Can we define revision ID as well?

I thought about that but then it would be like:

#define REVID_0_94	0x94

which does not really add much value IMHO.

> 
> > +                               community->features |= FEATURE_DEBOUNCE;
> > +               }
> > +
> >                 /* Read offset of the pad configuration registers */
> >                 padbar = readl(regs + PADBAR);
> >
> > @@ -1073,6 +1195,7 @@ int intel_pinctrl_suspend(struct device *dev)
> >         pads = pctrl->context.pads;
> >         for (i = 0; i < pctrl->soc->npins; i++) {
> >                 const struct pinctrl_pin_desc *desc = &pctrl->soc->pins[i];
> > +               void __iomem *padcfg;
> 
> padcfg2

And here also, we are going to save and restore padcfg3 in the future.

> > @@ -72,11 +73,15 @@ struct intel_community {
> >         unsigned pin_base;
> >         unsigned gpp_size;
> >         size_t npins;
> > +       unsigned features;
> >         void __iomem *regs;
> >         void __iomem *pad_regs;
> >         size_t ngpps;
> >  };
> >
> > +/* Additional features supported by the hardware */
> > +#define FEATURE_DEBOUNCE       BIT(0)
> 
> INTEL_PINCTRL_FEATURE_* ?

Indeed, that's better.

Thanks for the review :)