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Subject: Re: [PATCH] mfd: syscon: Add
 syscon_regmap_lookup_by_phandle_optional() function.
To:     Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        linux-kernel@vger.kernel.org
Cc:     Collabora Kernel ML <kernel@collabora.com>,
        Nicolas Boichat <drinkcat@chromium.org>,
        Arnd Bergmann <arnd@arndb.de>, Lee Jones <lee.jones@linaro.org>
References: <20201027211154.3371691-1-enric.balletbo@collabora.com>
From:   Matthias Brugger <matthias.bgg@gmail.com>
Message-ID: <d6e29e8b-9d5e-455b-24dc-7ec016c9b6b2@gmail.com>
Date:   Fri, 6 Nov 2020 08:40:09 +0100
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On 27/10/2020 22:11, Enric Balletbo i Serra wrote:
> This adds syscon_regmap_lookup_by_phandle_optional() function to get an
> optional regmap.
> 
> It behaves the same as syscon_regmap_lookup_by_phandle() except where
> there is no regmap phandle. In this case, instead of returning -ENODEV,
> the function returns NULL. This makes error checking simpler when the
> regmap phandle is optional.
> 
> Suggested-by: Nicolas Boichat <drinkcat@chromium.org>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

> ---
> 
>   drivers/mfd/syscon.c       | 13 +++++++++++++
>   include/linux/mfd/syscon.h | 11 +++++++++++
>   2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index ca465794ea9c..60c5c2b194cc 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -255,6 +255,19 @@ struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
>   }
>   EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_args);
>   
> +struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np,
> +					const char *property)
> +{
> +	struct regmap *regmap;
> +
> +	regmap = syscon_regmap_lookup_by_phandle(np, property);
> +	if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV)
> +		return NULL;
> +
> +	return regmap;
> +}
> +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_optional);
> +
>   static int syscon_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
> index 7f20e9b502a5..a1fe8aedced2 100644
> --- a/include/linux/mfd/syscon.h
> +++ b/include/linux/mfd/syscon.h
> @@ -28,6 +28,9 @@ extern struct regmap *syscon_regmap_lookup_by_phandle_args(
>   					const char *property,
>   					int arg_count,
>   					unsigned int *out_args);
> +extern struct regmap *syscon_regmap_lookup_by_phandle_optional(
> +					struct device_node *np,
> +					const char *property);
>   #else
>   static inline struct regmap *device_node_to_regmap(struct device_node *np)
>   {
> @@ -59,6 +62,14 @@ static inline struct regmap *syscon_regmap_lookup_by_phandle_args(
>   {
>   	return ERR_PTR(-ENOTSUPP);
>   }
> +
> +static inline struct regmap *syscon_regmap_lookup_by_phandle_optional(
> +					struct device_node *np,
> +					const char *property)
> +{
> +	return ERR_PTR(-ENOTSUPP);
> +}
> +
>   #endif
>   
>   #endif /* __LINUX_MFD_SYSCON_H__ */
>