Re: [PATCH v6 2/8] mfd: simple-mfd-i2c: specify max_register

[Alex Elder]

On 7/2/25 10:26 AM, Lee Jones wrote:
> On Fri, 27 Jun 2025, Alex Elder wrote:
>
> > All devices supported by simple MFD use the same 8-bit register
> > 8-bit value regmap configuration.  There is an option available
> > for a device to specify a custome configuration, but no existing
> > device uses it.
> >
> > Lee Jones suggested modifying the simple MFD implementation to
> > remove the generality of the full regmap configuration and add a
> > max_register value to the simple_mfd_data structure.  This can
> > be used in the regmap configuration to limit the valid register
> > addresses if desired.  It's simpler, and covers all existing and
> > anticipated device types.
>
> Woah, not like this.  I wanted to make the framework _more_ flexible.

OK, sorry I misunderstood.  I'll send another new version today
that does what you suggest.

Thanks a lot.

					-Alex

> Just this should do what you want:
>
> diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
> index 22159913bea0..f43be10c0e60 100644
> --- a/drivers/mfd/simple-mfd-i2c.c
> +++ b/drivers/mfd/simple-mfd-i2c.c
> @@ -44,6 +44,9 @@ static int simple_mfd_i2c_probe(struct i2c_client *i2c)
>          else
>                  regmap_config = simple_mfd_data->regmap_config;
>   
> +       if (simple_mfd_data->max_register)
> +               regmap_config->max_register = simple_mfd_data->max_register;
> +
>          regmap = devm_regmap_init_i2c(i2c, regmap_config);
>          if (IS_ERR(regmap))
>                  return PTR_ERR(regmap);
>
> Plus the one line change in drivers/mfd/simple-mfd-i2c.h.
>
> > Signed-off-by: Alex Elder <elder@xxxxxxxxxxxx>
> > Suggested-by: Lee Jones <lee@xxxxxxxxxx>
> > ---
> > v6: - New patch, changing the simple MFD functionality
> >
> >   drivers/mfd/simple-mfd-i2c.c | 18 ++++++------------
> >   drivers/mfd/simple-mfd-i2c.h |  2 +-
> >   2 files changed, 7 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
> > index 22159913bea03..c1dc315d44dcf 100644
> > --- a/drivers/mfd/simple-mfd-i2c.c
> > +++ b/drivers/mfd/simple-mfd-i2c.c
> > @@ -24,27 +24,21 @@
> >   
> >   #include "simple-mfd-i2c.h"
> >   
> > -static const struct regmap_config regmap_config_8r_8v = {
> > -	.reg_bits = 8,
> > -	.val_bits = 8,
> > -};
> > -
> >   static int simple_mfd_i2c_probe(struct i2c_client *i2c)
> >   {
> >   	const struct simple_mfd_data *simple_mfd_data;
> > -	const struct regmap_config *regmap_config;
> > +	struct regmap_config regmap_config = { };
> >   	struct regmap *regmap;
> >   	int ret;
> >   
> >   	simple_mfd_data = device_get_match_data(&i2c->dev);
> >   
> > -	/* If no regmap_config is specified, use the default 8reg and 8val bits */
> > -	if (!simple_mfd_data || !simple_mfd_data->regmap_config)
> > -		regmap_config = &regmap_config_8r_8v;
> > -	else
> > -		regmap_config = simple_mfd_data->regmap_config;
> > +	regmap_config.reg_bits = 8;
> > +	regmap_config.val_bits = 8;
> > +	if (simple_mfd_data)
> > +		regmap_config.max_register = simple_mfd_data->max_register;
> >   
> > -	regmap = devm_regmap_init_i2c(i2c, regmap_config);
> > +	regmap = devm_regmap_init_i2c(i2c, &regmap_config);
> >   	if (IS_ERR(regmap))
> >   		return PTR_ERR(regmap);
> >   
> > diff --git a/drivers/mfd/simple-mfd-i2c.h b/drivers/mfd/simple-mfd-i2c.h
> > index 7cb2bdd347d97..4121fe1bc1d70 100644
> > --- a/drivers/mfd/simple-mfd-i2c.h
> > +++ b/drivers/mfd/simple-mfd-i2c.h
> > @@ -24,9 +24,9 @@
> >   #include <linux/regmap.h>
> >   
> >   struct simple_mfd_data {
> > -	const struct regmap_config *regmap_config;
> >   	const struct mfd_cell *mfd_cell;
> >   	size_t mfd_cell_size;
> > +	unsigned int max_register;
> >   };
> >   
> >   #endif /* __MFD_SIMPLE_MFD_I2C_H */
> > --
> > 2.45.2