Re: [PATCH 2/3] iio: adc: Support ROHM BD79112 ADC/GPIO

[Matti Vaittinen <mazziesaccount@gmail.com>]

Hi deee Ho Linus,

Long time no chat. Thanks for the review!

On 03/09/2025 01:34, Linus Walleij wrote:
> Hi Matti,
> 
> On Tue, Sep 2, 2025 at 2:24 PM Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> The ROHM BD79112 is an ADC/GPIO with 32 channels. The channel inputs can
>> be used as ADC or GPIO. Using the GPIOs as IRQ sources isn't supported.
>>
>> The ADC is 12-bit, supporting input voltages up to 5.7V, and separate I/O
>> voltage supply. Maximum SPI clock rate is 20 MHz (10 MHz with
>> daisy-chain configuration) and maximum sampling rate is 1MSPS.
>>
>> The IC does also support CRC but it is not implemented in the driver.
>>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
>> +static int bd79112_gpio_dir_get(struct gpio_chip *gc, unsigned int offset)
>> +static int bd79112_gpio_get(struct gpio_chip *gc, unsigned int offset)
>> +static int bd79112_gpio_set(struct gpio_chip *gc, unsigned int offset,
>> +                           int value)
>> +static int bd79112_gpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
>> +                                    unsigned long *bits)
>> +static int bd79112_gpio_dir_set(struct bd79112_data *data, unsigned int offset,
>> +                               int dir)
>> +static int bd79112_gpio_input(struct gpio_chip *gc, unsigned int offset)
>> +static int bd79112_gpio_output(struct gpio_chip *gc, unsigned int offset,
>> +                              int value)
> 
> This looks like it could use
> 
> select GPIO_REGMAP
> 
> #include <linux/gpio/regmap.h>
> 
> struct gpio_regmap_config config = {};
> 
> etc. Did you check out the GPIO_REGMAP
> helper library?

I did - but that was couple of years ago :) I was very excited about it 
back then. I actually tried (tried hard, fingers almost bleeding) to 
write a patch to make it cover all of the ROHM PMIC GPIOs which I had to 
deal with. I thought it won't get it's full potential due to it's 
somewhat inflexible design. (And to tell the truth, I still believe so).

Anyways, fast-forward to this day, I don't see it handling valid_mask. I 
think it is a must for this device/driver, where pins can be either 
GPIOs or ADC inputs.

Yours,
	-- Matti