Re: [RESEND PATCH] regulator: userspace-consumer: Retrieve supplies from DT

[Zev Weiss]

Hi Naresh,

This looks basically alright to me, though a few suggested tweaks 
below...

On Fri, Sep 22, 2023 at 02:03:29AM PDT, Naresh Solanki wrote:
> From: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>
>
> Instead of hardcoding a single supply, retrieve supplies from DT.
>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>
> ---
> drivers/regulator/userspace-consumer.c | 43 ++++++++++++++++++++++++--
> 1 file changed, 40 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/regulator/userspace-consumer.c b/drivers/regulator/userspace-consumer.c
> index 97f075ed68c9..a3d3e1e6ca74 100644
> --- a/drivers/regulator/userspace-consumer.c
> +++ b/drivers/regulator/userspace-consumer.c
> @@ -115,11 +115,32 @@ static const struct attribute_group attr_group = {
> 	.is_visible =  attr_visible,
> };
>
> +#define SUPPLY_SUFFIX "-supply"
> +#define SUPPLY_SUFFIX_LEN 7

I think 'strlen(SUPPLY_SUFFIX)' would be preferable to a numeric literal 
here; it's less fragile and the compiler can evaluate it at compile-time 
anyway (not that it's likely to be performance-critical in this context 
I'd expect).

> +
> +static int get_num_supplies(struct platform_device *pdev)
> +{
> +	struct  property *prop;
> +	int num_supplies = 0;
> +
> +	for_each_property_of_node(pdev->dev.of_node, prop) {
> +		const char *prop_name = prop->name;
> +		int len = strlen(prop_name);
> +
> +		if (len > SUPPLY_SUFFIX_LEN &&
> +		    strcmp(prop_name + len - SUPPLY_SUFFIX_LEN, SUPPLY_SUFFIX) == 0) {
> +			num_supplies++;
> +		}

Preferred coding style is to omit braces around single-line 'if' blocks.

> +	}
> +	return num_supplies;
> +}
> +
> static int regulator_userspace_consumer_probe(struct platform_device *pdev)
> {
> 	struct regulator_userspace_consumer_data tmpdata;
> 	struct regulator_userspace_consumer_data *pdata;
> 	struct userspace_consumer_data *drvdata;
> +	struct  property *prop;

Looks like there's an extra space after 'struct' here.

> 	int ret;
>
> 	pdata = dev_get_platdata(&pdev->dev);
> @@ -131,11 +152,27 @@ static int regulator_userspace_consumer_probe(struct platform_device *pdev)
> 		memset(pdata, 0, sizeof(*pdata));
>
> 		pdata->no_autoswitch = true;
> -		pdata->num_supplies = 1;
> -		pdata->supplies = devm_kzalloc(&pdev->dev, sizeof(*pdata->supplies), GFP_KERNEL);
> +		pdata->num_supplies = get_num_supplies(pdev);
> +
> +		pdata->supplies = devm_kzalloc(&pdev->dev, pdata->num_supplies *
> +					       sizeof(*pdata->supplies), GFP_KERNEL);

Splitting the multiplication across two lines like that isn't great 
readability-wise IMO; it might be better to just assign it to a variable 
and use that instead to make things fit nicely.

> 		if (!pdata->supplies)
> 			return -ENOMEM;
> -		pdata->supplies[0].supply = "vout";
> +
> +		for_each_property_of_node(pdev->dev.of_node, prop) {
> +			const char *prop_name = prop->name;
> +			int len = strlen(prop_name);
> +
> +			if (len > SUPPLY_SUFFIX_LEN &&
> +			    strcmp(prop_name + len - SUPPLY_SUFFIX_LEN, SUPPLY_SUFFIX) == 0) {

Rather than duplicating this suffix-checking code, how about factoring 
out a helper function like prop_is_supply() or something to use both 
here and in get_num_supplies()?

Or actually to make it integrate here a little more nicely, you could 
have something like 'size_t prop_supply_name(char*)', returning zero if 
it doesn't end with "-supply", and the length of the name before the 
suffix if it does, so that get_num_supplies() could use it as a boolean 
and the code below could use the length to determine the allocation 
size.

> +				char *supply_name = devm_kzalloc(&pdev->dev,
> +								 len - SUPPLY_SUFFIX_LEN + 1,
> +								 GFP_KERNEL);
> +				strscpy(supply_name, prop_name, len - SUPPLY_SUFFIX_LEN);
> +				supply_name[len - SUPPLY_SUFFIX_LEN] = '\0';
> +				pdata->supplies[0].supply = supply_name;
> +			}
> +		}
> 	}
>
> 	if (pdata->num_supplies < 1) {
>
> base-commit: 451e85e29c9d6f20639d4cfcff4b9dea280178cc
> --
> 2.41.0