Re: [PATCH v3 07/22] mfd: adp5585: refactor how regmap defaults are handled

["Nuno Sá" <noname.nuno@gmail.com>]

On Tue, 2025-05-13 at 16:00 +0100, Lee Jones wrote:
> On Mon, 12 May 2025, Nuno Sá via B4 Relay wrote:
> 
> > From: Nuno Sá <nuno.sa@analog.com>
> > 
> > The only thing changing between variants is the regmap default
> > registers. Hence, instead of having a regmap condig for every variant
> > (duplicating lots of fields), add a chip info type of structure with a
> > regmap id to identify which defaults to use and populate regmap_config
> > at runtime given a template plus the id. Also note that between
> > variants, the defaults can be the same which means the chip info
> > structure can be used in more than one compatible.
> > 
> > This will also make it simpler adding new chips with more variants.
> > 
> > Also note that the chip info structures are deliberately not const as
> > they will also contain lots of members that are the same between the
> > different devices variants and so we will fill those at runtime.
> > 
> > Signed-off-by: Nuno Sá <nuno.sa@analog.com>
> > ---
> >  drivers/mfd/adp5585.c       | 94 +++++++++++++++++++++++++-----------------
> > ---
> >  include/linux/mfd/adp5585.h | 11 ++++++
> >  2 files changed, 64 insertions(+), 41 deletions(-)
> > 
> > diff --git a/drivers/mfd/adp5585.c b/drivers/mfd/adp5585.c
> > index
> > 19d4a0ab1bb4c261e82559630624059529765fbd..874aed7d7cfe052587720d899096c995c1
> > 9667af 100644
> > --- a/drivers/mfd/adp5585.c
> > +++ b/drivers/mfd/adp5585.c
> > @@ -81,41 +81,34 @@ static const u8
> > adp5585_regmap_defaults_04[ADP5585_MAX_REG + 1] = {
> >  	/* 0x38 */ 0x00, 0x00, 0x00, 0x00, 0x00,
> >  };
> >  
> > -enum adp5585_regmap_type {
> > -	ADP5585_REGMAP_00,
> > -	ADP5585_REGMAP_02,
> > -	ADP5585_REGMAP_04,
> > +static const struct regmap_config adp5585_regmap_config_template = {
> > +	.reg_bits = 8,
> > +	.val_bits = 8,
> > +	.max_register = ADP5585_MAX_REG,
> > +	.volatile_table = &adp5585_volatile_regs,
> > +	.cache_type = REGCACHE_MAPLE,
> > +	.num_reg_defaults_raw = ADP5585_MAX_REG + 1,
> >  };
> >  
> > -static const struct regmap_config adp5585_regmap_configs[] = {
> > -	[ADP5585_REGMAP_00] = {
> > -		.reg_bits = 8,
> > -		.val_bits = 8,
> > -		.max_register = ADP5585_MAX_REG,
> > -		.volatile_table = &adp5585_volatile_regs,
> > -		.cache_type = REGCACHE_MAPLE,
> > -		.reg_defaults_raw = adp5585_regmap_defaults_00,
> > -		.num_reg_defaults_raw = sizeof(adp5585_regmap_defaults_00),
> > -	},
> > -	[ADP5585_REGMAP_02] = {
> > -		.reg_bits = 8,
> > -		.val_bits = 8,
> > -		.max_register = ADP5585_MAX_REG,
> > -		.volatile_table = &adp5585_volatile_regs,
> > -		.cache_type = REGCACHE_MAPLE,
> > -		.reg_defaults_raw = adp5585_regmap_defaults_02,
> > -		.num_reg_defaults_raw = sizeof(adp5585_regmap_defaults_02),
> > -	},
> > -	[ADP5585_REGMAP_04] = {
> > -		.reg_bits = 8,
> > -		.val_bits = 8,
> > -		.max_register = ADP5585_MAX_REG,
> > -		.volatile_table = &adp5585_volatile_regs,
> > -		.cache_type = REGCACHE_MAPLE,
> > -		.reg_defaults_raw = adp5585_regmap_defaults_04,
> > -		.num_reg_defaults_raw = sizeof(adp5585_regmap_defaults_04),
> > -	},
> > -};
> > +static int adp5585_fill_regmap_config(const struct adp5585_dev *adp5585,
> > +				      struct regmap_config *regmap_config)
> 
> I like the general idea.  This is much more scaleable than before.
> 
> > +{
> > +	*regmap_config = adp5585_regmap_config_template;
> > +
> > +	switch (adp5585->info->regmap_type) {
> > +	case ADP5585_REGMAP_00:
> > +		regmap_config->reg_defaults_raw =
> > adp5585_regmap_defaults_00;
> > +		return 0;
> > +	case ADP5585_REGMAP_02:
> > +		regmap_config->reg_defaults_raw =
> > adp5585_regmap_defaults_02;
> > +		return 0;
> > +	case ADP5585_REGMAP_04:
> > +		regmap_config->reg_defaults_raw =
> > adp5585_regmap_defaults_04;
> 
> You could make this read a tiny bit nicer (as you do with the adp5585->info
> in a later patch) and make reg_defaults_raw a local variable.

I'm probably missing your point but what would be the benefit? The info is done
like that because I wanted the pointer to be 'const'. Here I do not think the
same applies...

> 
> > +		return 0;
> > +	default:
> > +		return -ENODEV;
> > +	}
> > +}
> >  
> >  static int adp5585_parse_fw(struct device *dev, struct adp5585_dev
> > *adp5585,
> >  			    struct mfd_cell **devs)
> > @@ -153,7 +146,7 @@ static void adp5585_osc_disable(void *data)
> >  
> >  static int adp5585_i2c_probe(struct i2c_client *i2c)
> >  {
> > -	const struct regmap_config *regmap_config;
> > +	struct regmap_config regmap_config;
> >  	struct adp5585_dev *adp5585;
> >  	struct mfd_cell *devs;
> >  	unsigned int id;
> > @@ -165,8 +158,15 @@ static int adp5585_i2c_probe(struct i2c_client *i2c)
> >  
> >  	i2c_set_clientdata(i2c, adp5585);
> >  
> > -	regmap_config = i2c_get_match_data(i2c);
> > -	adp5585->regmap = devm_regmap_init_i2c(i2c, regmap_config);
> > +	adp5585->info = i2c_get_match_data(i2c);
> > +	if (!adp5585->info)
> > +		return -ENODEV;
> > +
> > +	ret = adp5585_fill_regmap_config(adp5585, &regmap_config);
> > +	if (ret)
> > +		return ret;
> > +
> > +	adp5585->regmap = devm_regmap_init_i2c(i2c, &regmap_config);
> >  	if (IS_ERR(adp5585->regmap))
> >  		return dev_err_probe(&i2c->dev, PTR_ERR(adp5585->regmap),
> >  				     "Failed to initialize register
> > map\n");
> > @@ -223,22 +223,34 @@ static int adp5585_resume(struct device *dev)
> >  
> >  static DEFINE_SIMPLE_DEV_PM_OPS(adp5585_pm, adp5585_suspend,
> > adp5585_resume);
> >  
> > +static struct adp5585_info adp5585_info = {
> > +	.regmap_type = ADP5585_REGMAP_00,
> 
> Instead of providing this enum, then later another one (id) which is a
> subset of the same thing, why not pass just ADP5585_REGMAP_00, etc
> through the DT .data attribute then match on those?  It will add a
> couple of lines to the switch(info->id) statement, but will save on a
> boat load of static structs and other complexity.
> 
> For instance:
> 
> switch (info->id) {
> 	case ADP5585_MAN_ID_VALUE:
> 
> Would simply become:
> 
> switch (info->id) {
> 	case ADP5585_REGMAP_00:
> 	case ADP5585_REGMAP_02:
> 	case ADP5585_REGMAP_04:
> 
> And that's it.

I get the general idea... We will also have to pack the regmap defaults into an
array so that we can easily reference it with 'info->id' which I don't like too
much tbh (but I do see that adp5585_fill_chip_configs() will become simpler) . I
guess I can also just move everything into the "main" struct as we will fill
everything during probe (no real reason for struct adp5585_info) 

Anyways, If you prefer the above I'm not going to argue against it...

> 
> > +};
> > +
> > +static struct adp5585_info adp5585_02_info = {
> > +	.regmap_type = ADP5585_REGMAP_02,
> > +};
> > +
> > +static struct adp5585_info adp5585_04_info = {
> > +	.regmap_type = ADP5585_REGMAP_04,
> > +};
> > +
> >  static const struct of_device_id adp5585_of_match[] = {
> >  	{
> >  		.compatible = "adi,adp5585-00",
> > -		.data = &adp5585_regmap_configs[ADP5585_REGMAP_00],
> > +		.data = &adp5585_info,
> 
> 		.data = ADP5585_REGMAP_00,

I see, needs a cast but should work. I personally prefer valid pointers than
"encoding" integers in here. I know we can start the enum at 1 so that we can
still look for 0 for any possible issue but...


> 
> >  	}, {
> >  		.compatible = "adi,adp5585-01",
> > -		.data = &adp5585_regmap_configs[ADP5585_REGMAP_00],
> > +		.data = &adp5585_info,
> >  	}, {
> >  		.compatible = "adi,adp5585-02",
> > -		.data = &adp5585_regmap_configs[ADP5585_REGMAP_02],
> > +		.data = &adp5585_02_info,
> >  	}, {
> >  		.compatible = "adi,adp5585-03",
> > -		.data = &adp5585_regmap_configs[ADP5585_REGMAP_00],
> > +		.data = &adp5585_info,
> >  	}, {
> >  		.compatible = "adi,adp5585-04",
> > -		.data = &adp5585_regmap_configs[ADP5585_REGMAP_04],
> > +		.data = &adp5585_04_info,
> >  	},
> >  	{ /* sentinel */ }
> >  };
> > diff --git a/include/linux/mfd/adp5585.h b/include/linux/mfd/adp5585.h
> > index
> > 016033cd68e46757aca86d21dd37025fd354b801..4b48614970a811a8a95116faa20e58ea4f
> > 19ede6 100644
> > --- a/include/linux/mfd/adp5585.h
> > +++ b/include/linux/mfd/adp5585.h
> > @@ -119,8 +119,19 @@
> >  
> >  struct regmap;
> >  
> > +enum adp5585_regmap_type {
> > +	ADP5585_REGMAP_00,
> > +	ADP5585_REGMAP_02,
> > +	ADP5585_REGMAP_04,
> > +};
> > +
> > +struct adp5585_info {
> > +	enum adp5585_regmap_type regmap_type;
> > +};
> > +
> >  struct adp5585_dev {
> >  	struct regmap *regmap;
> > +	const struct adp5585_info *info;
> >  };
> >  
> >  #endif
> > 
> > -- 
> > 2.49.0
> > 
> >