linux-kernel - Re: [PATCH v3 2/3] pinctrl: tps6594: add for TPS6594 PMIC

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Date:   Fri, 5 May 2023 13:23:44 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Esteban Blanc <eblanc@...libre.com>,
        Michael Walle <michael@...le.cc>
Cc:     lgirdwood@...il.com, broonie@...nel.org, a.zummo@...ertech.it,
        alexandre.belloni@...tlin.com, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-rtc@...r.kernel.org,
        jpanis@...libre.com, jneanne@...libre.com, aseketeli@...libre.com,
        sterzik@...com, u-kumar1@...com
Subject: Re: [PATCH v3 2/3] pinctrl: tps6594: add for TPS6594 PMIC

On Wed, May 3, 2023 at 1:37 PM Esteban Blanc <eblanc@...libre.com> wrote:
> On Fri Apr 21, 2023 at 10:34 AM CEST, Linus Walleij wrote:
> > Hi Esteban,
> >
> > thanks for your patch!
> >
> > On Fri, Apr 14, 2023 at 12:12 PM Esteban Blanc <eblanc@...libre.com> wrote:
> >
> > > TI TPS6594 PMIC has 11 GPIOs which can be used for different
> > > functions.
> > >
> > > This add a pinctrl and pinmux drivers in order to use those functions.
> > >
> > > Signed-off-by: Esteban Blanc <eblanc@...libre.com>
> > (...)
> > > +config PINCTRL_TPS6594
> > > +       tristate "Pinctrl and GPIO driver for TI TPS6594 PMIC"
> > > +       depends on MFD_TPS6594
> > > +       default MFD_TPS6594
> > > +       select PINMUX
> > > +       select GPIOLIB
> >
> > select GPIO_REGMAP
> > ?
> >
> > I think this driver can use the GPIO_REGMAP helper library.
> >
> > Please look into other drivers using this, such as
> > drivers/gpio/gpio-sl28cpld.c
>
> I had a look at this driver and gpio-regmap.c. I think I understood
> what's going on, but I'm not sure how to handle the
> gpio_regmap_set_direction case. It is using the same reg_mask_xlate to
> determine the register and value to write as gpio_regmap_set or
> gpio_regmap_read. The problem is that this PMIC has 1 register per GPIO
> for the configuration (GPIOX_CONF registers with a bit for direction),
> while the in and out register are used for 8 pins (GPIO_OUT_1,
> GPIO_OUT_2 and GPIO_IN_1, GPIO_IN_2). This means that the register and
> mask returned by reg_mask_xlate will be erroneous in one or the other
> case.
>
> I noticed that I could override reg_mask_xlate, so I should be able to
> "just" match on the base address given as argument to perform a
> different computation depending on whether we are using reg_mask_xlate in
> a "direction change" or not, but somehow this feels a bit wrong.
>
> Is this the correct solution?
> Am I missing something?

This is a question for Michael Walle who wrote gpio-regmap,
Michael, what do you say?

Yours,
Linus Walleij