Re: [PATCH v1 2/6] device property: Add fwnode_property_match_property_string()

Jonathan Cameron
2023-08-09T17:59:52Z

On Tue, 8 Aug 2023 19:27:56 +0300
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> Sometimes the users want to match the single value string property
> against an array of predefined strings. Create a helper for them.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/base/property.c | 35 +++++++++++++++++++++++++++++++++++
> include/linux/property.h | 12 ++++++++++++
> 2 files changed, 47 insertions(+)
>
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 3bb9505f1631..8f8e2a6816bc 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -498,6 +498,41 @@ int fwnode_property_match_string(const struct fwnode_handle *fwnode,
> }
> EXPORT_SYMBOL_GPL(fwnode_property_match_string);
>
> +/**
> + * fwnode_property_match_property_string - find a property string value in an array and return index
> + * @fwnode: Firmware node to get the property of
> + * @propname: Name of the property holding the string value
> + * @array: String array to search in
> + * @n: Size of the @array
> + *
> + * Find a property string value in a given @array and if it is found return
> + * the index back.
> + *
> + * Return: index, starting from %0, if the string value was found in the @array (success),
> + * %-ENOENT when the string value was not found in the @array,
> + * %-EINVAL if given arguments are not valid,
> + * %-ENODATA if the property does not have a value,
> + * %-EPROTO or %-EILSEQ if the property is not a string,
> + * %-ENXIO if no suitable firmware interface is present.
> + */
> +int fwnode_property_match_property_string(const struct fwnode_handle *fwnode,
> + const char *propname, const char * const *array, size_t n)

Hi Andy,

Whilst I'm not 100% sold on adding ever increasing complexity to what we
match, this one feels like a common enough thing to be worth providing.

Looking at the usecases I wonder if it would be better to pass in
an unsigned int *ret which is only updated on a match?

That way the common properties approach of not checking the return value
if we have an optional property would apply.

e.g. patch 3 would end up with a block that looks like:

st->input_mode = ADMV1014_IQ_MODE;
device_property_match_property_string(&spi->dev, "adi,input-mode",
input_mode_names,
ARRAY_SIZE(input_mode_names),
&st->input_mode);

Only neat and tidy if the thing being optionally read into is an unsigned int
though (otherwise you still need a local variable)

Jonathan

> +{
> + const char *string;
> + int ret;
> +
> + ret = fwnode_property_read_string(fwnode, propname, &string);
> + if (ret)
> + return ret;
> +
> + ret = match_string(array, n, string);
> + if (ret < 0)
> + ret = -ENOENT;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(fwnode_property_match_property_string);
> +
> /**
> * fwnode_property_get_reference_args() - Find a reference with arguments
> * @fwnode: Firmware node where to look for the reference
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 8c3c6685a2ae..11f3ad6814f2 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -97,6 +97,18 @@ static inline bool device_is_compatible(const struct device *dev, const char *co
> return fwnode_device_is_compatible(dev_fwnode(dev), compat);
> }
>
> +int fwnode_property_match_property_string(const struct fwnode_handle *fwnode,
> + const char *propname,
> + const char * const *array, size_t n);
> +
> +static inline
> +int device_property_match_property_string(const struct device *dev,
> + const char *propname,
> + const char * const *array, size_t n)
> +{
> + return fwnode_property_match_property_string(dev_fwnode(dev), propname, array, n);
> +}
> +
> int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
> const char *prop, const char *nargs_prop,
> unsigned int nargs, unsigned int index,