* [PATCH] mfd: syscon: Add syscon_regmap_lookup_by_phandle_optional() function.
@ 2020-10-27 21:11 Enric Balletbo i Serra
2020-11-06 7:40 ` Matthias Brugger
[not found] ` <CAK8P3a0r8vaL8Mc=EVZCrqW4s8uvhfBjLRfGCEc4jp7W6Z_dUQ@mail.gmail.com>
0 siblings, 2 replies; 3+ messages in thread
From: Enric Balletbo i Serra @ 2020-10-27 21:11 UTC (permalink / raw)
To: linux-kernel
Cc: Collabora Kernel ML, Nicolas Boichat, Arnd Bergmann, Lee Jones
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>
---
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__ */
--
2.28.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mfd: syscon: Add syscon_regmap_lookup_by_phandle_optional() function.
2020-10-27 21:11 [PATCH] mfd: syscon: Add syscon_regmap_lookup_by_phandle_optional() function Enric Balletbo i Serra
@ 2020-11-06 7:40 ` Matthias Brugger
[not found] ` <CAK8P3a0r8vaL8Mc=EVZCrqW4s8uvhfBjLRfGCEc4jp7W6Z_dUQ@mail.gmail.com>
1 sibling, 0 replies; 3+ messages in thread
From: Matthias Brugger @ 2020-11-06 7:40 UTC (permalink / raw)
To: Enric Balletbo i Serra, linux-kernel
Cc: Collabora Kernel ML, Nicolas Boichat, Arnd Bergmann, Lee Jones
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__ */
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mfd: syscon: Add syscon_regmap_lookup_by_phandle_optional() function.
[not found] ` <CAK8P3a0r8vaL8Mc=EVZCrqW4s8uvhfBjLRfGCEc4jp7W6Z_dUQ@mail.gmail.com>
@ 2020-11-06 10:23 ` Arnd Bergmann
0 siblings, 0 replies; 3+ messages in thread
From: Arnd Bergmann @ 2020-11-06 10:23 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Enric Balletbo i Serra, linux-kernel, Collabora Kernel ML,
Nicolas Boichat, Lee Jones
I noticed that my earlier reply was rejected by some mail servers,
resending from @kernel.org to make sure everyone has it.
On Tue, Oct 27, 2020 at 10:57 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Tue, Oct 27, 2020 at 10:11 PM Enric Balletbo i Serra
> <enric.balletbo@collabora.com> 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>
>
> Looks good in principle.
>
> > @@ -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;
> > +}
>
> I think the explanation from the patch description is needed here as well,
> as an interface that might either return an error code or NULL is generally
> a really bad idea. I understand what this is for, but it's easy to misread.
>
> > 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);
> > +}
>
> Shouldn't this also return NULL then?
>
> Arnd
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2020-10-27 21:11 [PATCH] mfd: syscon: Add syscon_regmap_lookup_by_phandle_optional() function Enric Balletbo i Serra
2020-11-06 7:40 ` Matthias Brugger
[not found] ` <CAK8P3a0r8vaL8Mc=EVZCrqW4s8uvhfBjLRfGCEc4jp7W6Z_dUQ@mail.gmail.com>
2020-11-06 10:23 ` Arnd Bergmann
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