[ARM] omap: create a proper tree of clocks

Traditionally, we've tracked the parent/child relationships between
clk structures by setting the child's parent member to point at the
upstream clock.  As a result, when decending the tree, we have had
to scan all clocks to find the children.

Avoid this wasteful scanning by keeping a list of the clock's children.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 37 insertions, 21 deletions

diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
index 54da27af0bd5..6a1737a74477 100644
--- a/arch/arm/plat-omap/clock.c
+++ b/arch/arm/plat-omap/clock.c
@@ -143,8 +143,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	if (ret == 0) {
 		if (clk->recalc)
 			clk->recalc(clk);
-		if (clk->flags & RATE_PROPAGATES)
-			propagate_rate(clk);
+		propagate_rate(clk);
 	}
 	spin_unlock_irqrestore(&clockfw_lock, flags);
 
@@ -166,8 +165,7 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
 	if (ret == 0) {
 		if (clk->recalc)
 			clk->recalc(clk);
-		if (clk->flags & RATE_PROPAGATES)
-			propagate_rate(clk);
+		propagate_rate(clk);
 	}
 	spin_unlock_irqrestore(&clockfw_lock, flags);
 
@@ -214,24 +212,31 @@ void followparent_recalc(struct clk *clk)
 	clk->rate = clk->parent->rate;
 }
 
+void clk_reparent(struct clk *child, struct clk *parent)
+{
+	list_del_init(&child->sibling);
+	if (parent)
+		list_add(&child->sibling, &parent->children);
+	child->parent = parent;
+
+	/* now do the debugfs renaming to reattach the child
+	   to the proper parent */
+}
+
 /* Propagate rate to children */
 void propagate_rate(struct clk * tclk)
 {
 	struct clk *clkp;
 
-	if (tclk == NULL || IS_ERR(tclk))
-		return;
-
-	list_for_each_entry(clkp, &clocks, node) {
-		if (likely(clkp->parent != tclk))
-			continue;
+	list_for_each_entry(clkp, &tclk->children, sibling) {
 		if (clkp->recalc)
 			clkp->recalc(clkp);
-		if (clkp->flags & RATE_PROPAGATES)
-			propagate_rate(clkp);
+		propagate_rate(clkp);
 	}
 }
 
+static LIST_HEAD(root_clks);
+
 /**
  * recalculate_root_clocks - recalculate and propagate all root clocks
  *
@@ -243,16 +248,18 @@ void recalculate_root_clocks(void)
 {
 	struct clk *clkp;
 
-	list_for_each_entry(clkp, &clocks, node) {
-		if (!clkp->parent) {
-			if (clkp->recalc)
-				clkp->recalc(clkp);
-			if (clkp->flags & RATE_PROPAGATES)
-				propagate_rate(clkp);
-		}
+	list_for_each_entry(clkp, &root_clks, sibling) {
+		if (clkp->recalc)
+			clkp->recalc(clkp);
+		propagate_rate(clkp);
 	}
 }
 
+void clk_init_one(struct clk *clk)
+{
+	INIT_LIST_HEAD(&clk->children);
+}
+
 int clk_register(struct clk *clk)
 {
 	if (clk == NULL || IS_ERR(clk))
@@ -265,6 +272,11 @@ int clk_register(struct clk *clk)
 		return 0;
 
 	mutex_lock(&clocks_mutex);
+	if (clk->parent)
+		list_add(&clk->sibling, &clk->parent->children);
+	else
+		list_add(&clk->sibling, &root_clks);
+
 	list_add(&clk->node, &clocks);
 	if (clk->init)
 		clk->init(clk);
@@ -280,6 +292,7 @@ void clk_unregister(struct clk *clk)
 		return;
 
 	mutex_lock(&clocks_mutex);
+	list_del(&clk->sibling);
 	list_del(&clk->node);
 	mutex_unlock(&clocks_mutex);
 }
diff --git a/arch/arm/plat-omap/include/mach/clock.h b/arch/arm/plat-omap/include/mach/clock.h
index 8705902de1d6..af6ae4fa46d6 100644
--- a/arch/arm/plat-omap/include/mach/clock.h
+++ b/arch/arm/plat-omap/include/mach/clock.h
@@ -70,6 +70,8 @@ struct clk {
 	const char		*name;
 	int			id;
 	struct clk		*parent;
+	struct list_head	children;
+	struct list_head	sibling;	/* node for children */
 	unsigned long		rate;
 	__u32			flags;
 	void __iomem		*enable_reg;
@@ -115,7 +117,9 @@ struct clk_functions {
 extern unsigned int mpurate;
 
 extern int clk_init(struct clk_functions *custom_clocks);
+extern void clk_init_one(struct clk *clk);
 extern int clk_register(struct clk *clk);
+extern void clk_reparent(struct clk *child, struct clk *parent);
 extern void clk_unregister(struct clk *clk);
 extern void propagate_rate(struct clk *clk);
 extern void recalculate_root_clocks(void);
@@ -131,8 +135,7 @@ extern const struct clkops clkops_null;
 /* Clock flags */
 /* bit 0 is free */
 #define RATE_FIXED		(1 << 1)	/* Fixed clock rate */
-#define RATE_PROPAGATES		(1 << 2)	/* Program children too */
-/* bits 3-4 are free */
+/* bits 2-4 are free */
 #define ENABLE_REG_32BIT	(1 << 5)	/* Use 32-bit access */
 #define CLOCK_IDLE_CONTROL	(1 << 7)
 #define CLOCK_NO_IDLE_PARENT	(1 << 8)