clk: implement clk clk_hw_get_parent_by_index

This is the inverse operation to clk_get_parent_index and is already
implemented inline in clk_get_parent. Factor that code out for use by
the incoming STM32MP13 clock driver.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20231127064947.2207726-7-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/clk.h b/include/linux/clk.h
index 269664b0ba..6a33f28ee6 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -129,6 +129,7 @@ int clk_hw_set_rate(struct clk_hw *hw, unsigned long rate);
  */
 int clk_set_parent(struct clk *clk, struct clk *parent);
 int clk_hw_set_parent(struct clk_hw *hw, struct clk_hw *hwp);
+struct clk_hw *clk_hw_get_parent_by_index(const struct clk_hw *hw, unsigned int idx);
 
 /**
  * clk_get_parent - get the parent clock source for this clock