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

[Bartosz Golaszewski <bgolaszewski@baylibre.com>]

pt., 29 lis 2019 o 10:07 Marco Felsch <m.felsch@pengutronix.de> napisał(a):
>
> On 19-11-28 11:47, Bartosz Golaszewski wrote:
> > 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.
>
> So it is okay to keep the above select and change it later?
>

Yes, we don't want to stop you from getting this upstream. We'll
convert it once the new module is ready.

Bart

> Regards,
>   Marco
>
> > 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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> >
>
> --
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |