[PATCH RFC] clk: add support for automatic parent handling

[Uwe Kleine-König]

Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
Hello,

only compile tested so far.

Best regards
Uwe

 drivers/clk/clk.c   |   43 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/clk.h |    8 ++++++++
 2 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 264c809..7627815 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -14,10 +14,23 @@
 int clk_prepare(struct clk *clk)
 {
 	int ret = 0;
+	struct clk *parent = ERR_PTR(-ENOSYS);
 
 	if (!clk)
 		return 0;
 
+	if (clk->ops->flags & CLK_OPS_GENERIC_PARENT) {
+		parent = clk_get_parent(clk);
+
+		if (!IS_ERR(parent)) {
+			ret = clk_prepare(parent);
+			if (ret)
+				return ret;
+		} else if (PTR_ERR(parent) != -ENOSYS)
+			/* -ENOSYS means no parent and is OK */
+			return PTR_ERR(parent);
+	}
+
 	mutex_lock(&clk->prepare_lock);
 	if (clk->prepare_count == 0 && clk->ops->prepare)
 		ret = clk->ops->prepare(clk);
@@ -26,6 +39,9 @@ int clk_prepare(struct clk *clk)
 		clk->prepare_count++;
 	mutex_unlock(&clk->prepare_lock);
 
+	if (ret && !IS_ERR(parent))
+		clk_unprepare(parent);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_prepare);
@@ -45,6 +61,12 @@ void clk_unprepare(struct clk *clk)
 	}
 
 	mutex_unlock(&clk->prepare_lock);
+
+	if (clk->ops->flags & CLK_OPS_GENERIC_PARENT) {
+		struct clk *parent = clk_get_parent(clk);
+		if (!IS_ERR(parent))
+			clk_unprepare(parent);
+	}
 }
 EXPORT_SYMBOL_GPL(clk_unprepare);
 
@@ -52,10 +74,22 @@ int clk_enable(struct clk *clk)
 {
 	unsigned long flags;
 	int ret = 0;
+	struct clk *parent = ERR_PTR(-ENOSYS);
 
 	if (!clk)
 		return 0;
 
+	if (clk->ops->flags & CLK_OPS_GENERIC_PARENT) {
+		parent = clk_get_parent(clk);
+		if (!IS_ERR(parent)) {
+			ret = clk_enable(parent);
+			if (ret)
+				return ret;
+		} else if (PTR_ERR(parent) != -ENOSYS)
+			/* -ENOSYS means no parent and is OK */
+			return PTR_ERR(parent);
+	}
+
 	WARN_ON(clk->prepare_count == 0);
 
 	spin_lock_irqsave(&clk->enable_lock, flags);
@@ -66,6 +100,9 @@ int clk_enable(struct clk *clk)
 		clk->enable_count++;
 	spin_unlock_irqrestore(&clk->enable_lock, flags);
 
+	if (ret && !IS_ERR(parent))
+		clk_disable(parent);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_enable);
@@ -85,6 +122,12 @@ void clk_disable(struct clk *clk)
 		clk->ops->disable(clk);
 
 	spin_unlock_irqrestore(&clk->enable_lock, flags);
+
+	if (clk->ops->flags & CLK_OPS_GENERIC_PARENT) {
+		struct clk *parent = clk_get_parent(clk);
+		if (!IS_ERR(parent))
+			clk_disable(parent);
+	}
 }
 EXPORT_SYMBOL_GPL(clk_disable);
 
diff --git a/include/linux/clk.h b/include/linux/clk.h
index d2f0db0..125e525 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -62,6 +62,11 @@ struct clk {
 	.prepare_lock	= __MUTEX_INITIALIZER(name.prepare_lock),	\
 }
 
+/* bit definitions for struct clk_ops.flags */
+#define CLK_OPS_GENERIC_PARENT	1	/* automatically handle parent in
+					   enable, disable, prepare and
+					   unprepare functions */
+
 /**
  * struct clk_ops -  Callback operations for clocks; these are to be provided
  * by the clock implementation, and will be called by drivers through the clk_*
@@ -91,6 +96,8 @@ struct clk {
  * @put:	Called by the core clock code when a devices driver releases a
  *		clock via clk_put(). Optional.
  *
+ * @flags:	see above for possible values.
+ *
  * The clk_enable/clk_disable and clk_prepare/clk_unprepare pairs allow
  * implementations to split any work between atomic (enable) and sleepable
  * (prepare) contexts.  If a clock requires sleeping code to be turned on, this
@@ -119,6 +126,7 @@ struct clk_ops {
 	int		(*set_rate)(struct clk *, unsigned long);
 	int		(*set_parent)(struct clk *, struct clk *);
 	struct clk *	(*get_parent)(struct clk *);
+	unsigned int	flags;
 };
 
 /**
-- 
1.7.4.1