From: Sowjanya Komatineni <skomatineni@nvidia.com>
Date: Fri, 16 Aug 2019 12:41:52 -0700
Subject: clk: Add API to get index of the clock parent

Git-commit: d9b86cc48283112f06738d45031b88bd3f9ecb92
Patch-mainline: v5.5-rc1
References: jsc#SLE-9391,jsc#SLE-9388,jsc#SLE-10608

This patch adds a new clk_hw_get_parent_index() function that can be
used to retrieve the index of a given clock's parent. This can be useful
for restoring a clock on system resume.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/clk/clk.c            |   18 ++++++++++++++++++
 include/linux/clk-provider.h |    1 +
 2 files changed, 19 insertions(+)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1672,6 +1672,24 @@ static int clk_fetch_parent_index(struct
 	return i;
 }
 
+/**
+ * clk_hw_get_parent_index - return the index of the parent clock
+ * @hw: clk_hw associated with the clk being consumed
+ *
+ * Fetches and returns the index of parent clock. Returns -EINVAL if the given
+ * clock does not have a current parent.
+ */
+int clk_hw_get_parent_index(struct clk_hw *hw)
+{
+	struct clk_hw *parent = clk_hw_get_parent(hw);
+
+	if (WARN_ON(parent == NULL))
+		return -EINVAL;
+
+	return clk_fetch_parent_index(hw->core, parent->core);
+}
+EXPORT_SYMBOL_GPL(clk_hw_get_parent_index);
+
 /*
  * Update the orphan status of @core and all its children.
  */
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -817,6 +817,7 @@ unsigned int clk_hw_get_num_parents(cons
 struct clk_hw *clk_hw_get_parent(const struct clk_hw *hw);
 struct clk_hw *clk_hw_get_parent_by_index(const struct clk_hw *hw,
 					  unsigned int index);
+int clk_hw_get_parent_index(struct clk_hw *hw);
 unsigned int __clk_get_enable_count(struct clk *clk);
 unsigned long clk_hw_get_rate(const struct clk_hw *hw);
 unsigned long __clk_get_flags(struct clk *clk);