clk: introduce clk_set_phase function & callback

A common operation for a clock signal generator is to shift the phase of
that signal. This patch introduces a new function to the clk.h API to
dynamically adjust the phase of a clock signal. Additionally this patch
introduces support for the new function in the common clock framework
via the .set_phase call back in struct clk_ops.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>

3 files changed, 35 insertions, 0 deletions

diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index efbf70b9fd84..845be30be50f 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -46,6 +46,7 @@ struct clk {
         unsigned int            enable_count;
         unsigned int            prepare_count;
         unsigned long           accuracy;
+        int                     phase;
         struct hlist_head       children;
         struct hlist_node       child_node;
         unsigned int            notifier_count;
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 411dd7eb2653..201a6195a3eb 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -129,6 +129,10 @@ struct dentry;
  *              set then clock accuracy will be initialized to parent accuracy
  *              or 0 (perfect clock) if clock has no parent.
  *
+ * @set_phase:  Shift the phase this clock signal in degrees specified
+ *              by the second argument. Valid values for degrees are
+ *              0-359. Return 0 on success, otherwise -EERROR.
+ *
  * @init:       Perform platform-specific initialization magic.
  *              This is not not used by any of the basic clock types.
  *              Please consider other ways of solving initialization problems
@@ -177,6 +181,7 @@ struct clk_ops {
                                     unsigned long parent_rate, u8 index);
         unsigned long   (*recalc_accuracy)(struct clk_hw *hw,
                                            unsigned long parent_accuracy);
+        int             (*set_phase)(struct clk_hw *hw, int degrees);
         void            (*init)(struct clk_hw *hw);
         int             (*debug_init)(struct clk_hw *hw, struct dentry *dentry);
 };
diff --git a/include/linux/clk.h b/include/linux/clk.h
index fb5e097d8f72..38bdedd3e389 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -106,6 +106,25 @@ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  */
 long clk_get_accuracy(struct clk *clk);
 
+/**
+ * clk_set_phase - adjust the phase shift of a clock signal
+ * @clk: clock signal source
+ * @degrees: number of degrees the signal is shifted
+ *
+ * Shifts the phase of a clock signal by the specified degrees. Returns 0 on
+ * success, -EERROR otherwise.
+ */
+int clk_set_phase(struct clk *clk, int degrees);
+
+/**
+ * clk_get_phase - return the phase shift of a clock signal
+ * @clk: clock signal source
+ *
+ * Returns the phase shift of a clock node in degrees, otherwise returns
+ * -EERROR.
+ */
+int clk_get_phase(struct clk *clk);
+
 #else
 
 static inline long clk_get_accuracy(struct clk *clk)
@@ -113,6 +132,16 @@ static inline long clk_get_accuracy(struct clk *clk)
         return -ENOTSUPP;
 }
 
+static inline long clk_set_phase(struct clk *clk, int phase)
+{
+        return -ENOTSUPP;
+}
+
+static inline long clk_get_phase(struct clk *clk)
+{
+        return -ENOTSUPP;
+}
+
 #endif
 
 /**