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clk: <linux/clk.h> fixes and improvements

PATCH Applied Geert Uytterhoeven 2 participants 7 messages Dec 1, 2025 – Jan 16

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Common clk Clk API
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Geert Uytterhoeven

author
#0 lore raw

cover clk: <linux/clk.h> fixes and improvements

Hi Russell, Stephen, Mike,

This patch series contains improvements for <linux/clk.h>. The first patch fixes a bug reported by the kernel test robot. The other patches improve readability.

Thanks for your comments!

Geert Uytterhoeven (3):
clk: Move clk_{save,restore}_context() to COMMON_CLK section
clk: Merge prepare and unprepare sections
clk: Annotate #else and #endif

 include/linux/clk.h | 104 ++++++++++++++++++++++----------------------
 1 file changed, 52 insertions(+), 52 deletions(-)
Signature · 12 lines
2.43.0

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
author
#1 lore raw

PATCH 1/3 clk: Move clk_{save,restore}_context() to COMMON_CLK section

The clk_save_context() and clk_restore_context() helpers are only implemented by the Common Clock Framework. They are not available when using legacy clock frameworks. Dummy implementations are provided, but only if no clock support is available at all.

Hence when CONFIG_HAVE_CLK=y, but CONFIG_COMMON_CLK is not enabled:

    m68k-linux-gnu-ld: drivers/net/phy/air_en8811h.o: in function `en8811h_resume':
    air_en8811h.c:(.text+0x83e): undefined reference to `clk_restore_context'
    m68k-linux-gnu-ld: drivers/net/phy/air_en8811h.o: in function `en8811h_suspend':
    air_en8811h.c:(.text+0x856): undefined reference to `clk_save_context'

Fix this by moving forward declarations and dummy implementions from the HAVE_CLK to the COMMON_CLK section.

Fixes 8b95d1ce3300c411 ("clk: Add functions to save/restore clock context en-masse")
Reported-by kernel test robot <[email protected]>
Closes https://lore.kernel.org/oe-kbuild-all/[email protected]/ open here
Signed-off-by Geert Uytterhoeven <[email protected]>
---
 include/linux/clk.h | 48 ++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 24 deletions(-)
include/linux/clk.h +24 -24
index b607482ca77e987b..64ff118ffb1a1d7d 100644
@@ -228,6 +228,23 @@ int devm_clk_rate_exclusive_get(struct device *dev, struct clk *clk);
  */
 void clk_rate_exclusive_put(struct clk *clk);
 
+/**
+ * clk_save_context - save clock context for poweroff
+ *
+ * Saves the context of the clock register for powerstates in which the
+ * contents of the registers will be lost. Occurs deep within the suspend
+ * code so locking is not necessary.
+ */
+int clk_save_context(void);
+
+/**
+ * clk_restore_context - restore clock context after poweroff
+ *
+ * This occurs with all clocks enabled. Occurs deep within the resume code
+ * so locking is not necessary.
+ */
+void clk_restore_context(void);
+
 #else
 
 static inline int clk_notifier_register(struct clk *clk,

@@ -293,6 +310,13 @@ static inline int devm_clk_rate_exclusive_get(struct device *dev, struct clk *cl
 
 static inline void clk_rate_exclusive_put(struct clk *clk) {}
 
+static inline int clk_save_context(void)
+{
+	return 0;
+}
+
+static inline void clk_restore_context(void) {}
+
 #endif
 
 #ifdef CONFIG_HAVE_CLK_PREPARE

@@ -933,23 +957,6 @@ struct clk *clk_get_parent(struct clk *clk);
  */
 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 
-/**
- * clk_save_context - save clock context for poweroff
- *
- * Saves the context of the clock register for powerstates in which the
- * contents of the registers will be lost. Occurs deep within the suspend
- * code so locking is not necessary.
- */
-int clk_save_context(void);
-
-/**
- * clk_restore_context - restore clock context after poweroff
- *
- * This occurs with all clocks enabled. Occurs deep within the resume code
- * so locking is not necessary.
- */
-void clk_restore_context(void);
-
 #else /* !CONFIG_HAVE_CLK */
 
 static inline struct clk *clk_get(struct device *dev, const char *id)

@@ -1129,13 +1136,6 @@ static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 	return NULL;
 }
 
-static inline int clk_save_context(void)
-{
-	return 0;
-}
-
-static inline void clk_restore_context(void) {}
-
 #endif
 
 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
Signature · 1 line
2.43.0
author
#2 lore raw

PATCH 2/3 clk: Merge prepare and unprepare sections

<linux/clk.h> contains two consecutive #ifdef/#else/#endif sections that check for CONFIG_HAVE_CLK_PREPARE: one for prepare-related functionality, and a second for unprepare-related functionality. Reduce #ifdef clutter by merging them.

Signed-off-by Geert Uytterhoeven <[email protected]>
---
 include/linux/clk.h | 46 ++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)
include/linux/clk.h +23 -23
index 64ff118ffb1a1d7d..9e5291f37c50c78a 100644
@@ -329,8 +329,21 @@ static inline void clk_restore_context(void) {}
  * Must not be called from within atomic context.
  */
 int clk_prepare(struct clk *clk);
+
+/**
+ * clk_unprepare - undo preparation of a clock source
+ * @clk: clock source
+ *
+ * This undoes a previously prepared clock.  The caller must balance
+ * the number of prepare and unprepare calls.
+ *
+ * Must not be called from within atomic context.
+ */
+void clk_unprepare(struct clk *clk);
+
 int __must_check clk_bulk_prepare(int num_clks,
 				  const struct clk_bulk_data *clks);
+void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks);
 
 /**
  * clk_is_enabled_when_prepared - indicate if preparing a clock also enables it.

@@ -355,41 +368,28 @@ static inline int clk_prepare(struct clk *clk)
 	return 0;
 }
 
-static inline int __must_check
-clk_bulk_prepare(int num_clks, const struct clk_bulk_data *clks)
+static inline void clk_unprepare(struct clk *clk)
 {
 	might_sleep();
-	return 0;
 }
 
-static inline bool clk_is_enabled_when_prepared(struct clk *clk)
-{
-	return false;
-}
-#endif
-
-/**
- * clk_unprepare - undo preparation of a clock source
- * @clk: clock source
- *
- * This undoes a previously prepared clock.  The caller must balance
- * the number of prepare and unprepare calls.
- *
- * Must not be called from within atomic context.
- */
-#ifdef CONFIG_HAVE_CLK_PREPARE
-void clk_unprepare(struct clk *clk);
-void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks);
-#else
-static inline void clk_unprepare(struct clk *clk)
+static inline int __must_check
+clk_bulk_prepare(int num_clks, const struct clk_bulk_data *clks)
 {
 	might_sleep();
+	return 0;
 }
+
 static inline void clk_bulk_unprepare(int num_clks,
 				      const struct clk_bulk_data *clks)
 {
 	might_sleep();
 }
+
+static inline bool clk_is_enabled_when_prepared(struct clk *clk)
+{
+	return false;
+}
 #endif
 
 #ifdef CONFIG_HAVE_CLK
Signature · 1 line
2.43.0
maintainer Applied
#3 lore raw

Re: [PATCH 2/3] clk: Merge prepare and unprepare sections

Quoting Geert Uytterhoeven (2025-12-01 02:42:27)

Quoted 7 lines

<linux/clk.h> contains two consecutive #ifdef/#else/#endif sections that check for CONFIG_HAVE_CLK_PREPARE: one for prepare-related functionality, and a second for unprepare-related functionality. Reduce #ifdef clutter by merging them.

Signed-off-by Geert Uytterhoeven <[email protected]>

---

Applied to clk-next

author
#4 lore raw

PATCH 3/3 clk: Annotate #else and #endif

In reply to Geert Uytterhoeven

Annotate the #else and #endif keywords in large #ifdef/#else/#endif sections, to improve readability.

Signed-off-by Geert Uytterhoeven <[email protected]>
---
 include/linux/clk.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
include/linux/clk.h +5 -5
index 9e5291f37c50c78a..efb91604d3f667e2 100644
@@ -245,7 +245,7 @@ int clk_save_context(void);
  */
 void clk_restore_context(void);
 
-#else
+#else /* !CONFIG_COMMON_CLK */
 
 static inline int clk_notifier_register(struct clk *clk,
 					struct notifier_block *nb)

@@ -317,7 +317,7 @@ static inline int clk_save_context(void)
 
 static inline void clk_restore_context(void) {}
 
-#endif
+#endif /* !CONFIG_COMMON_CLK */
 
 #ifdef CONFIG_HAVE_CLK_PREPARE
 /**

@@ -361,7 +361,7 @@ void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks);
  * to be right.
  */
 bool clk_is_enabled_when_prepared(struct clk *clk);
-#else
+#else /* !CONFIG_HAVE_CLK_PREPARE */
 static inline int clk_prepare(struct clk *clk)
 {
 	might_sleep();

@@ -390,7 +390,7 @@ static inline bool clk_is_enabled_when_prepared(struct clk *clk)
 {
 	return false;
 }
-#endif
+#endif /* !CONFIG_HAVE_CLK_PREPARE */
 
 #ifdef CONFIG_HAVE_CLK
 /**

@@ -1136,7 +1136,7 @@ static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 	return NULL;
 }
 
-#endif
+#endif /* !CONFIG_HAVE_CLK */
 
 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 static inline int clk_prepare_enable(struct clk *clk)
Signature · 1 line
2.43.0
maintainer Applied
#5 lore raw

Re: [PATCH 3/3] clk: Annotate #else and #endif

Quoting Geert Uytterhoeven (2025-12-01 02:42:28)

Quoted 5 lines

Annotate the #else and #endif keywords in large #ifdef/#else/#endif sections, to improve readability.

Signed-off-by Geert Uytterhoeven <[email protected]>

---

Applied to clk-next

maintainer Applied
#6 lore raw

Re: [PATCH 1/3] clk: Move clk_{save,restore}_context() to COMMON_CLK section

In reply to Geert Uytterhoeven

Quoting Geert Uytterhoeven (2025-12-01 02:42:26)

Quoted 12 lines

The clk_save_context() and clk_restore_context() helpers are only implemented by the Common Clock Framework. They are not available when using legacy clock frameworks. Dummy implementations are provided, but only if no clock support is available at all.

Hence when CONFIG_HAVE_CLK=y, but CONFIG_COMMON_CLK is not enabled:

    m68k-linux-gnu-ld: drivers/net/phy/air_en8811h.o: in function `en8811h_resume':
    air_en8811h.c:(.text+0x83e): undefined reference to `clk_restore_context'
    m68k-linux-gnu-ld: drivers/net/phy/air_en8811h.o: in function `en8811h_suspend':
    air_en8811h.c:(.text+0x856): undefined reference to `clk_save_context'
Quoted 8 lines

Fix this by moving forward declarations and dummy implementions from the HAVE_CLK to the COMMON_CLK section.

Fixes 8b95d1ce3300c411 ("clk: Add functions to save/restore clock context en-masse")
Reported-by kernel test robot <[email protected]>
Closes https://lore.kernel.org/oe-kbuild-all/[email protected]/ open here
Signed-off-by Geert Uytterhoeven <[email protected]>

---

Applied to clk-next