[PATCH] clk: add a function to retrieve a clk_hw instance from a clkspec definition

[Boris Brezillon]

of_clk_hw_get_from_provider() is providing a way to retrieve a clk_hw
instance from a clkspec definition. Which is usefull in case a clk driver
wants to get one of its own instance from a clkspec, without allocating a
new per-user clk struct.

Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
---
 drivers/clk/clk.c            | 36 ++++++++++++++++++++++++++++++++++++
 include/linux/clk-provider.h |  1 +
 2 files changed, 37 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index f13c3f4..fbef1b7 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3001,6 +3001,42 @@ void of_clk_del_provider(struct device_node *np)
 }
 EXPORT_SYMBOL_GPL(of_clk_del_provider);
 
+/**
+ * of_clk_hw_get_from_provider() - Look for a clk_hw instance registered with
+ *				   the given clkspec definition.
+ * @clkspec: pointer to a clock specifier data structure
+ *
+ * This function looks up a struct clk_hw from the registered list of clock
+ * providers, an input is a clock specifier data structure as returned
+ * from the of_parse_phandle_with_args() function call.
+ */
+struct clk_hw *of_clk_hw_get_from_provider(struct of_phandle_args *clkspec)
+{
+	struct clk_hw *clk_hw = ERR_PTR(-EPROBE_DEFER);
+	struct of_clk_provider *provider;
+
+	if (!clkspec)
+		return ERR_PTR(-EINVAL);
+
+	/* Check if we have such a provider in our array */
+	mutex_lock(&of_clk_mutex);
+	list_for_each_entry(provider, &of_clk_providers, link) {
+		struct clk *clk = ERR_PTR(-EPROBE_DEFER);
+
+		if (provider->node == clkspec->np)
+			clk = provider->get(clkspec, provider->data);
+
+		if (!IS_ERR(clk)) {
+			clk_hw = __clk_get_hw(clk);
+			break;
+		}
+	}
+	mutex_unlock(&of_clk_mutex);
+
+	return clk_hw;
+}
+EXPORT_SYMBOL_GPL(of_clk_hw_get_from_provider);
+
 struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
 				       const char *dev_id, const char *con_id)
 {
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index c56988a..bb62517 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -645,6 +645,7 @@ void devm_clk_unregister(struct device *dev, struct clk *clk);
 const char *__clk_get_name(const struct clk *clk);
 const char *clk_hw_get_name(const struct clk_hw *hw);
 struct clk_hw *__clk_get_hw(struct clk *clk);
+struct clk_hw *of_clk_hw_get_from_provider(struct of_phandle_args *clkspec);
 unsigned int clk_hw_get_num_parents(const struct clk_hw *hw);
 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,