clk: add clk_set_parent()

Clocks may support multiple parents: this change introduces an
optional operation on the clk-uclass to set a clock's parent.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: David Wu <david.wu@rock-chips.com>

Series-changes: 2
- Fixed David's email address.

(cherry picked from commit f7d1046da18fd03a047b5f4d290a8ab8550ebf73)

Change-Id: I92065a132988a66b7d86a936766429ea024f4d1e
Signed-off-by: David Wu <david.wu@rock-chips.com>

drivers/clk/clk-uclass.c

@@ -208,6 +208,18 @@ int clk_set_phase(struct clk *clk, int degrees)
 	return ops->set_phase(clk, degrees);
 }
 
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+	const struct clk_ops *ops = clk_dev_ops(clk->dev);
+
+	debug("%s(clk=%p, parent=%p)\n", __func__, clk, parent);
+
+	if (!ops->set_parent)
+		return -ENOSYS;
+
+	return ops->set_parent(clk, parent);
+}
+
 int clk_enable(struct clk *clk)
 {
 	const struct clk_ops *ops = clk_dev_ops(clk->dev);

include/clk-uclass.h

@@ -94,6 +94,14 @@ struct clk_ops {
 	 * @return 0 on success, or -ve error code.
 	 */
 	int (*set_phase)(struct clk *clk, int degrees);
+	/**
+	 * set_parent() - Set current clock parent
+	 *
+	 * @clk:        The clock to manipulate.
+	 * @parent:     New clock parent.
+	 * @return zero on success, or -ve error code.
+	 */
+	int (*set_parent)(struct clk *clk, struct clk *parent);
 	/**
 	 * enable() - Enable a clock.
 	 *

include/clk.h

@@ -197,6 +197,17 @@ int clk_get_phase(struct clk *clk);
  */
 int clk_set_phase(struct clk *clk, int degrees);
 
+/**
+ * clk_set_parent() - Set current clock parent.
+ *
+ * @clk:	A clock struct that was previously successfully requested by
+ *		clk_request/get_by_*().
+ * @parent:	A clock struct that was previously successfully requested by
+ *		clk_request/get_by_*().
+ * @return new rate, or -ve error code.
+ */
+int clk_set_parent(struct clk *clk, struct clk *parent);
+
 /**
  * clk_enable() - Enable (turn on) a clock.
  *