Re: [PATCH v2 3/3] pinctrl: da9062: add driver support

[Bartosz Golaszewski <bgolaszewski@baylibre.com>]

śr., 27 lis 2019 o 16:01 Marco Felsch <m.felsch@pengutronix.de> napisał(a):
>
> Hi Linus,
>
> On 19-11-27 14:49, Linus Walleij wrote:
> > Hi Marco,
> >
> > thanks for your patch!
>
> thanks for your fast response.
>
> > On Wed, Nov 27, 2019 at 12:56 PM Marco Felsch <m.felsch@pengutronix.de> wrote:
> >
> > > The DA9062 is a mfd pmic device which supports 5 GPIOs. The GPIOs can
> > > be used as input, output or have a special use-case.
> > >
> > > The patch adds the support for the normal input/output use-case.
> > >
> > > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > (...)
> >
> > > +config PINCTRL_DA9062
> > > +       tristate "Dialog Semiconductor DA9062 PMIC pinctrl and GPIO Support"
> > > +       depends on MFD_DA9062
> > > +       select GPIOLIB
> >
> > Hm this would be one of those that could use GENERIC_REGMAP_GPIO
> > the day we invent it but we haven't invented it yet.
>
> Yes it is. Is there a plan for GENERIC_REGMAP_GPIO?
>

Yes, it's the second item on my TODO after the LINEINFO_FD series. I
just got a board I can use for developing this so I should have
something shortly.

Bart

> > > +#include <../gpio/gpiolib.h>
> >
> > Put a comment above this telling us why you do this thing.
>
> Okay.
>
> > > +static int da9062_gpio_get(struct gpio_chip *gc, unsigned int offset)
> > > +{
> > (...)
> > > +       return val & BIT(offset);
> >
> > You should #include <linux/bits.h> since you use BIT()
>
> Argh.. of course I will add the include.
>
> > Usually I clamp it like this:
> > return !!(val & BIT(offset));
>
> Okay, I can change that too.
>
> > > +static int da9062_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> > > +{
> > > +       struct da9062_pctl *pctl = gpiochip_get_data(gc);
> > > +       struct regmap *regmap = pctl->da9062->regmap;
> > > +       int gpio_mode;
> > > +
> > > +       gpio_mode = da9062_pctl_get_pin_mode(regmap, offset);
> > > +       if (gpio_mode < 0)
> > > +               return gpio_mode;
> > > +
> > > +       switch (gpio_mode) {
> > > +       case DA9062_PIN_ALTERNATE:
> > > +               return -ENOTSUPP;
> > > +       case DA9062_PIN_GPI:
> > > +               return 1;
> > > +       case DA9062_PIN_GPO_OD:
> > > +       case DA9062_PIN_GPO_PP:
> > > +               return 0;
> >
> > We recently added defines for these directions in
> > <linux/gpio/driver.h>:
> >
> > #define GPIO_LINE_DIRECTION_IN  1
> > #define GPIO_LINE_DIRECTION_OUT 0
> >
> > Please use these. (Soon in Torvald's tree, else
> > in my "devel" branch.)
>
> I rebased it onto your devel, thanks for the hint.
>
> > > +static int da9062_gpio_direction_input(struct gpio_chip *gc,
> > > +                                      unsigned int offset)
> > > +{
> > > +       struct da9062_pctl *pctl = gpiochip_get_data(gc);
> > > +       struct regmap *regmap = pctl->da9062->regmap;
> > > +       struct gpio_desc *desc = gpiochip_get_desc(gc, offset);
> > > +       unsigned int gpi_type;
> > > +       int ret;
> > > +
> > > +       ret = da9062_pctl_set_pin_mode(regmap, offset, DA9062_PIN_GPI);
> > > +       if (ret)
> > > +               return ret;
> > > +
> > > +       /*
> > > +        * If the gpio is active low we should set it in hw too. No worries
> > > +        * about gpio_get() because we read and return the gpio-level. So the
> > > +        * gpiolib active_low handling is still correct.
> > > +        *
> > > +        * 0 - active low, 1 - active high
> > > +        */
> > > +       gpi_type = !gpiod_is_active_low(desc);
> >
> > That's interesting. Correct too, I guess.
>
> Double checked it again and the datasheet calls it gpio-level so I
> assume that this is correct.
>
> > > +static int da9062_gpio_direction_output(struct gpio_chip *gc,
> > > +                                       unsigned int offset, int value)
> > > +{
> > > +       /* Push-Pull / Open-Drain options are configured during set_config */
> > > +       da9062_gpio_set(gc, offset, value);
> >
> > That looks dangerous. There is no guarantee that .set_config()
> > always gets called.
>
> Hm.. it seems that other drivers using this assumption too:
>   - gpio-lp87565.c
>   - gpio-tps65218.c
>   - ...
>
> But you're right I missed the possible users of
> gpiod_direction_output_raw().
>
> > Please create a local state container for the mode of each pin in
> > struct da9062_pctl and set it to push-pull by default at probe, then
> > set this to whatever the state is here and let the .set_config()
> > alter it later if need be.
> >
> > If we don't do that you will get boot-time defaults I think and that
> > might create bugs.
>
> I will add a container for each pin, thanks for covering that.
>
> > > +static int da9062_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
> > > +                                 unsigned long config)
> > > +{
> > (...)
> > > +       case PIN_CONFIG_DRIVE_OPEN_DRAIN:
> > > +               return da9062_pctl_set_pin_mode(regmap, offset,
> > > +                                               DA9062_PIN_GPO_OD);
> > > +       case PIN_CONFIG_DRIVE_PUSH_PULL:
> > > +               return da9062_pctl_set_pin_mode(regmap, offset,
> > > +                                               DA9062_PIN_GPO_PP);
> >
> > So also store this in the per-pin state.
>
> Of course.
>
> Regards,
>   Marco
>
> >
> > Yours,
> > Linus Walleij
> >
>
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