Re: [PATCH v2 3/3] gpio: gpio-ltc4283: Add support for the LTC4283 Swap Controller

["Nuno Sá" <noname.nuno@gmail.com>]

On Thu, 2025-09-04 at 21:57 +0200, Linus Walleij wrote:
> Hi Nuno,
> 
> thanks for your patch!
> 
> On Wed, Sep 3, 2025 at 12:04 PM Nuno Sá via B4 Relay
> <devnull+nuno.sa.analog.com@kernel.org> wrote:
> 
> > From: Nuno Sá <nuno.sa@analog.com>
> > 
> > The LTC4283 device has up to 8 pins that can be configured as GPIOs.
> > 
> > Note that PGIO pins are not set as GPIOs by default so if they are
> > configured to be used as GPIOs we need to make sure to initialize them
> > to a sane default. They are set as inputs by default.
> > 
> > Signed-off-by: Nuno Sá <nuno.sa@analog.com>
> 
> (...)
> 
> > +config GPIO_LTC4283
> > +       tristate "Analog Devices LTC4283 GPIO support"
> > +       depends on SENSORS_LTC4283
> 
> Could that be
> depends on REGMAP && (SENSOR_LTC4283 || COMPILE_TEST)
> ?
> 
> Or does something blow up if you do that? (I guess it also needs
> AUXBUS but more on that below)
> 

(forgot to reply to this)

Hmm SENSOR_LTC4283 already depends on that and REGMAP (and selects AUXBUS) so
isn't enough to depend on SENSOR_LTC4283? Or is the above so that we can do
COMPILE_TEST?

- Nuno Sá

> should it also be
> 
> default SENSOR_LTC4283
> 
> Sof if that is compiled in (=y) or module (=m) then this becomes
> the same by default?
> 
> > +       help
> > +         If you say yes here you want the GPIO function available in Analog
> > +         Devices LTC4283 Negative Voltage Hot Swap Controller.
> > +
> > +         This driver can also be built as a module. If so, the module will
> > +         be called gpio-ltc4283.
> > +
> >  config GPIO_MB86S7X
> 
> This is placed among the memory-mapped drivers, but:
> 
> > +#include <linux/auxiliary_bus.h>
> (...)
> > +static struct auxiliary_driver ltc4283_gpio_driver = {
> > +       .probe = ltc4283_gpio_probe,
> > +       .id_table = ltc4283_aux_id_table,
> > +};
> > +module_auxiliary_driver(ltc4283_gpio_driver);
> 
> Create a new submenu for auxiliary bus drivers and add it
> there. We already have a submenu for MFD so why not?
> 
> menu "AUXBUS GPIO expanders"
>   depends on AUXILIARY_BUS
> ...
> 
> Have you looked into using GPIO_REGMAP?
> I guess some specials are used here so maybe it is
> not possible.
> 
> Yours,
> Linus Walleij