[PATCH v9 0/2] clk: Add functions to get optional clocks

[PATCH v9 0/2] clk: Add functions to get optional clocks

[Phil Edworthy]

Quite a few drivers get an optional clock, e.g. a bus clock required to 
access peripheral's registers that is always enabled on some devices.

v9:
 - Add a separate patch to add a comment about __of_clk_get_by_name() error
   values.
 - Add brackets after devm_clk_get so people know it's a function.
 - Add kernel doc for clk_get_optional().


Phil Edworthy (2):
  clk: Add comment about __of_clk_get_by_name() error values
  clk: Add (devm_)clk_get_optional() functions

 drivers/clk/clk-devres.c | 11 +++++++++++
 drivers/clk/clkdev.c     |  6 ++++++
 include/linux/clk.h      | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+)

-- 
2.17.1

[PATCH v9 1/2] clk: Add comment about __of_clk_get_by_name() error values

[Phil Edworthy]

It's not immediately obvious from the code that failure to get a
clock provider can return either -ENOENT or -EINVAL. Therefore, add
a comment to highlight this.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
---
 drivers/clk/clkdev.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 9ab3db8b3988..cc5df3970cd3 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -52,6 +52,12 @@ struct clk *of_clk_get(struct device_node *np, int index)
 }
 EXPORT_SYMBOL(of_clk_get);
 
+/*
+ * Beware the return values when np is valid, but no clock provider is found.
+ * If name = NULL, the function returns -ENOENT.
+ * If name != NULL, the function returns -EINVAL. This is because __of_clk_get()
+ * is called even if of_property_match_string() returns an error.
+ */
 static struct clk *__of_clk_get_by_name(struct device_node *np,
 					const char *dev_id,
 					const char *name)
-- 
2.17.1

[PATCH v9 2/2] clk: Add (devm_)clk_get_optional() functions

[Phil Edworthy]

This adds clk_get_optional() and devm_clk_get_optional() functions to get
optional clocks.
They behave the same as (devm_)clk_get() except where there is no clock
producer. In this case, instead of returning -ENOENT, the function
returns NULL. This makes error checking simpler and allows
clk_prepare_enable, etc to be called on the returned reference
without additional checks.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v9:
 - Add brackets after devm_clk_get so people know it's a function.
 - Add kernel doc for clk_get_optional().
v8:
 - Remove else clause
v7:
 - Instead of messing with the core functions, simply wrap them for the
   _optional() versions. By putting clk_get_optional() inline in the header
   file, we can get rid of the arch specific patches as well.
v6:
 - Add doxygen style comment for devm_clk_get_optional() args
v5:
 - No changes.
v4:
 - No changes.
v3:
 - No changes.
---
 drivers/clk/clk-devres.c | 11 +++++++++++
 include/linux/clk.h      | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
index 12c87457eca1..8e8893168676 100644
--- a/drivers/clk/clk-devres.c
+++ b/drivers/clk/clk-devres.c
@@ -34,6 +34,17 @@ struct clk *devm_clk_get(struct device *dev, const char *id)
 }
 EXPORT_SYMBOL(devm_clk_get);
 
+struct clk *devm_clk_get_optional(struct device *dev, const char *id)
+{
+	struct clk *clk = devm_clk_get(dev, id);
+
+	if (clk == ERR_PTR(-ENOENT))
+		return NULL;
+
+	return clk;
+}
+EXPORT_SYMBOL(devm_clk_get_optional);
+
 struct clk_bulk_devres {
 	struct clk_bulk_data *clks;
 	int num_clks;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index a7773b5c0b9f..d8bc1a856b39 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -383,6 +383,17 @@ int __must_check devm_clk_bulk_get_all(struct device *dev,
  */
 struct clk *devm_clk_get(struct device *dev, const char *id);
 
+/**
+ * devm_clk_get_optional - lookup and obtain a managed reference to an optional
+ *			   clock producer.
+ * @dev: device for clock "consumer"
+ * @id: clock consumer ID
+ *
+ * Behaves the same as devm_clk_get() except where there is no clock producer.
+ * In this case, instead of returning -ENOENT, the function returns NULL.
+ */
+struct clk *devm_clk_get_optional(struct device *dev, const char *id);
+
 /**
  * devm_get_clk_from_child - lookup and obtain a managed reference to a
  *			     clock producer from child node.
@@ -718,6 +729,12 @@ static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 	return NULL;
 }
 
+static inline struct clk *devm_clk_get_optional(struct device *dev,
+						const char *id)
+{
+	return NULL;
+}
+
 static inline int __must_check devm_clk_bulk_get(struct device *dev, int num_clks,
 						 struct clk_bulk_data *clks)
 {
@@ -862,6 +879,25 @@ static inline void clk_bulk_disable_unprepare(int num_clks,
 	clk_bulk_unprepare(num_clks, clks);
 }
 
+/**
+ * clk_get_optional - lookup and obtain a reference to an optional clock
+ *		      producer.
+ * @dev: device for clock "consumer"
+ * @id: clock consumer ID
+ *
+ * Behaves the same as clk_get() except where there is no clock producer. In
+ * this case, instead of returning -ENOENT, the function returns NULL.
+ */
+static inline struct clk *clk_get_optional(struct device *dev, const char *id)
+{
+	struct clk *clk = clk_get(dev, id);
+
+	if (clk == ERR_PTR(-ENOENT))
+		return NULL;
+
+	return clk;
+}
+
 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 struct clk *of_clk_get(struct device_node *np, int index);
 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
-- 
2.17.1

Re: [PATCH v9 1/2] clk: Add comment about __of_clk_get_by_name() error values

[Andy Shevchenko]

On Mon, Dec 03, 2018 at 11:13:08AM +0000, Phil Edworthy wrote:
> It's not immediately obvious from the code that failure to get a
> clock provider can return either -ENOENT or -EINVAL. Therefore, add
> a comment to highlight this.

> +/*
> + * Beware the return values when np is valid, but no clock provider is found.
> + * If name = NULL, the function returns -ENOENT.
> + * If name != NULL, the function returns -EINVAL. This is because __of_clk_get()

I would start new sentence from new line
(this will emphasize the possible variants)

 * This is ...

 Otherwise looks good to me:

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> + * is called even if of_property_match_string() returns an error.
> + */
>  static struct clk *__of_clk_get_by_name(struct device_node *np,
>  					const char *dev_id,
>  					const char *name)
> -- 
> 2.17.1
> 

-- 
With Best Regards,
Andy Shevchenko

RE: [PATCH v9 1/2] clk: Add comment about __of_clk_get_by_name() error values

[Phil Edworthy]

Hi Andy,

On 03 December 2018 13:31 Andy Shevchenko wrote:
> On Mon, Dec 03, 2018 at 11:13:08AM +0000, Phil Edworthy wrote:
> > It's not immediately obvious from the code that failure to get a clock
> > provider can return either -ENOENT or -EINVAL. Therefore, add a
> > comment to highlight this.
> 
> > +/*
> > + * Beware the return values when np is valid, but no clock provider is
> found.
> > + * If name = NULL, the function returns -ENOENT.
> > + * If name != NULL, the function returns -EINVAL. This is because
> > +__of_clk_get()
> 
> I would start new sentence from new line (this will emphasize the possible
> variants)
> 
>  * This is ...
I disagree, the explanation is specifically related to the case where the function
returns -EINVAL. Though this is a nit, so I'm not really bothered either way.

Thanks for the review!
Phil

>  Otherwise looks good to me:
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> > + * is called even if of_property_match_string() returns an error.
> > + */
> >  static struct clk *__of_clk_get_by_name(struct device_node *np,
> >  					const char *dev_id,
> >  					const char *name)
> > --
> > 2.17.1
> >
> 
> --
> With Best Regards,
> Andy Shevchenko
> 

RE: [PATCH v9 1/2] clk: Add comment about __of_clk_get_by_name() error values

[Phil Edworthy]

Hi,

Any other comments on this patch and patch 2/2 (https://lkml.org/lkml/2018/12/3/326)?

Thanks
Phil

> -----Original Message-----
> From: Phil Edworthy
> Sent: 06 December 2018 12:31
> To: 'Andy Shevchenko' <andriy.shevchenko@linux.intel.com>
> Cc: Michael Turquette <mturquette@baylibre.com>; Stephen Boyd
> <sboyd@kernel.org>; Russell King <linux@armlinux.org.uk>; Geert
> Uytterhoeven <geert@linux-m68k.org>; Uwe Kleine-König <u.kleine-
> koenig@pengutronix.de>; linux-clk@vger.kernel.org; linux-
> kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: RE: [PATCH v9 1/2] clk: Add comment about
> __of_clk_get_by_name() error values
> 
> Hi Andy,
> 
> On 03 December 2018 13:31 Andy Shevchenko wrote:
> > On Mon, Dec 03, 2018 at 11:13:08AM +0000, Phil Edworthy wrote:
> > > It's not immediately obvious from the code that failure to get a
> > > clock provider can return either -ENOENT or -EINVAL. Therefore, add
> > > a comment to highlight this.
> >
> > > +/*
> > > + * Beware the return values when np is valid, but no clock provider
> > > +is
> > found.
> > > + * If name = NULL, the function returns -ENOENT.
> > > + * If name != NULL, the function returns -EINVAL. This is because
> > > +__of_clk_get()
> >
> > I would start new sentence from new line (this will emphasize the
> > possible
> > variants)
> >
> >  * This is ...
> I disagree, the explanation is specifically related to the case where the
> function returns -EINVAL. Though this is a nit, so I'm not really bothered
> either way.
> 
> Thanks for the review!
> Phil
> 
> >  Otherwise looks good to me:
> >
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >
> > > + * is called even if of_property_match_string() returns an error.
> > > + */
> > >  static struct clk *__of_clk_get_by_name(struct device_node *np,
> > >  					const char *dev_id,
> > >  					const char *name)
> > > --
> > > 2.17.1
> > >
> >
> > --
> > With Best Regards,
> > Andy Shevchenko
> >

Re: [PATCH v9 1/2] clk: Add comment about __of_clk_get_by_name() error values

[Andy Shevchenko]

On Wed, Jan 16, 2019 at 03:18:42PM +0000, Phil Edworthy wrote:
> Hi,
> 
> Any other comments on this patch and patch 2/2 (https://lkml.org/lkml/2018/12/3/326)?

Was on vacations, sorry.

> > > I would start new sentence from new line (this will emphasize the
> > > possible
> > > variants)
> > >
> > >  * This is ...
> > I disagree, the explanation is specifically related to the case where the
> > function returns -EINVAL. Though this is a nit, so I'm not really bothered
> > either way.

Ah, okay. You may bear my tags on.


-- 
With Best Regards,
Andy Shevchenko