linux-kernel - Re: [PATCH v6 2/8] mfd: simple-mfd-i2c: specify max

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Message-ID: <0219b698-2f1b-4fcd-bce7-0ba6f6895b11@riscstar.com>
Date: Wed, 2 Jul 2025 10:35:11 -0500
From: Alex Elder <elder@...cstar.com>
To: Lee Jones <lee@...nel.org>
Cc: lgirdwood@...il.com, broonie@...nel.org, alexandre.belloni@...tlin.com,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, mat.jonczyk@...pl,
 dlan@...too.org, paul.walmsley@...ive.com, palmer@...belt.com,
 aou@...s.berkeley.edu, alex@...ti.fr, troymitchell988@...il.com,
 guodong@...cstar.com, linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/8] mfd: simple-mfd-i2c: specify max_register

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@...cstar.com>
>> Suggested-by: Lee Jones <lee@...nel.org>
>> ---
>> 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
>>
>