[PATCH 2/2] clk: clk-composite: implement setting rate by reparenting

[Sascha Hauer]

Support setting the clock rate by reparenting the mux clock. For now
only use the mux clock for setting the rate when the rate clock is not
present. Using both clocks for finding the best rate is left as a future
exercise.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/clk/clk-composite.c | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
index 3ed628c919..479ac5e8ef 100644
--- a/drivers/clk/clk-composite.c
+++ b/drivers/clk/clk-composite.c
@@ -57,9 +57,18 @@ static long clk_composite_round_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct clk_composite *composite = to_clk_composite(hw);
 	struct clk *rate_clk = composite->rate_clk;
+	struct clk *mux_clk = composite->mux_clk;
 	struct clk_hw *rate_hw = clk_to_clk_hw(rate_clk);
 
-	return rate_clk ? rate_clk->ops->round_rate(rate_hw, rate, prate) : 0;
+	if (rate_clk)
+		return rate_clk->ops->round_rate(rate_hw, rate, prate);
+
+	if (!(hw->clk.flags & CLK_SET_RATE_NO_REPARENT) &&
+	    mux_clk &&
+	    mux_clk->ops->set_rate)
+		return mux_clk->ops->round_rate(clk_to_clk_hw(mux_clk), rate, prate);
+
+	return *prate;
 }
 
 static int clk_composite_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -67,10 +76,23 @@ static int clk_composite_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct clk_composite *composite = to_clk_composite(hw);
 	struct clk *rate_clk = composite->rate_clk;
+	struct clk *mux_clk = composite->mux_clk;
 	struct clk_hw *rate_hw = clk_to_clk_hw(rate_clk);
 
-	return rate_clk ?
-		rate_clk->ops->set_rate(rate_hw, rate, parent_rate) : 0;
+	/*
+	 * When the rate clock is present use that to set the rate,
+	 * otherwise try the mux clock. We currently do not support
+	 * to find the best rate using a combination of both.
+	 */
+	if (rate_clk)
+		return rate_clk->ops->set_rate(rate_hw, rate, parent_rate);
+
+	if (!(hw->clk.flags & CLK_SET_RATE_NO_REPARENT) &&
+	    mux_clk &&
+	    mux_clk->ops->set_rate)
+		return mux_clk->ops->set_rate(clk_to_clk_hw(mux_clk), rate, parent_rate);
+
+	return 0;
 }
 
 static int clk_composite_is_enabled(struct clk_hw *hw)
@@ -137,6 +159,12 @@ struct clk *clk_register_composite(const char *name,
 	if (ret)
 		goto err;
 
+	if (composite->mux_clk) {
+		composite->mux_clk->parents = composite->hw.clk.parents;
+		composite->mux_clk->parent_names = composite->hw.clk.parent_names;
+		composite->mux_clk->num_parents = composite->hw.clk.num_parents;
+	}
+
 	return &composite->hw.clk;
 
 err:
-- 
2.29.2