From: Phil Edworthy <phil.edworthy@renesas.com>
Date: Mon, 3 Dec 2018 11:13:09 +0000
Subject: clk: Add (devm_)clk_get_optional() functions
Git-commit: 60b8f0ddf1a927ef02141a6610fd52575134f821
Patch-mainline: 5.1-rc1
References: git-fixes

This adds clk_get_optional() and devm_clk_get_optional() functions to get
optional clocks.

They behave the same as (devm_)clk_get() except where there is no clock
producer. In this case, instead of returning -ENOENT, the function
returns NULL. This makes error checking simpler and allows
clk_prepare_enable, etc to be called on the returned reference
without additional checks.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Russell King <linux@armlinux.org.uk>
[sboyd@kernel.org: Document in devres.txt]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 Documentation/driver-model/devres.txt |    1 
 drivers/clk/clk-devres.c              |   11 ++++++++++
 include/linux/clk.h                   |   36 ++++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -235,6 +235,7 @@ certainly invest a bit more effort into
 
 CLOCK
   devm_clk_get()
+  devm_clk_get_optional()
   devm_clk_put()
   devm_clk_hw_register()
 
--- a/drivers/clk/clk-devres.c
+++ b/drivers/clk/clk-devres.c
@@ -34,6 +34,17 @@ struct clk *devm_clk_get(struct device *
 }
 EXPORT_SYMBOL(devm_clk_get);
 
+struct clk *devm_clk_get_optional(struct device *dev, const char *id)
+{
+	struct clk *clk = devm_clk_get(dev, id);
+
+	if (clk == ERR_PTR(-ENOENT))
+		return NULL;
+
+	return clk;
+}
+EXPORT_SYMBOL(devm_clk_get_optional);
+
 struct clk_bulk_devres {
 	struct clk_bulk_data *clks;
 	int num_clks;
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -316,6 +316,17 @@ int __must_check devm_clk_bulk_get(struc
 struct clk *devm_clk_get(struct device *dev, const char *id);
 
 /**
+ * devm_clk_get_optional - lookup and obtain a managed reference to an optional
+ *			   clock producer.
+ * @dev: device for clock "consumer"
+ * @id: clock consumer ID
+ *
+ * Behaves the same as devm_clk_get() except where there is no clock producer.
+ * In this case, instead of returning -ENOENT, the function returns NULL.
+ */
+struct clk *devm_clk_get_optional(struct device *dev, const char *id);
+
+/**
  * devm_get_clk_from_child - lookup and obtain a managed reference to a
  *			     clock producer from child node.
  * @dev: device for clock "consumer"
@@ -565,6 +576,12 @@ static inline struct clk *devm_clk_get(s
 	return NULL;
 }
 
+static inline struct clk *devm_clk_get_optional(struct device *dev,
+						const char *id)
+{
+	return NULL;
+}
+
 static inline int devm_clk_bulk_get(struct device *dev, int num_clks,
 				    struct clk_bulk_data *clks)
 {
@@ -679,6 +696,25 @@ static inline void clk_bulk_disable_unpr
 	clk_bulk_unprepare(num_clks, clks);
 }
 
+/**
+ * clk_get_optional - lookup and obtain a reference to an optional clock
+ *		      producer.
+ * @dev: device for clock "consumer"
+ * @id: clock consumer ID
+ *
+ * Behaves the same as clk_get() except where there is no clock producer. In
+ * this case, instead of returning -ENOENT, the function returns NULL.
+ */
+static inline struct clk *clk_get_optional(struct device *dev, const char *id)
+{
+	struct clk *clk = clk_get(dev, id);
+
+	if (clk == ERR_PTR(-ENOENT))
+		return NULL;
+
+	return clk;
+}
+
 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 struct clk *of_clk_get(struct device_node *np, int index);
 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);