clk: Add clk_bulk_get_optional() function

clk_bulk_get_optional() allows to get a group of clocks where one
or more is optional.  For a not available clock, e.g. not specifed
in the clock consumer node in DT, its respective struct clk pointer
will be NULL.  This allows for operating on a group of returned
clocks (struct clk_bulk_data array) with existing clk_bulk* APIs.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-bulk.c

@@ -75,8 +75,8 @@ void clk_bulk_put(int num_clks, struct clk_bulk_data *clks)
 }
 EXPORT_SYMBOL_GPL(clk_bulk_put);
 
-int __must_check clk_bulk_get(struct device *dev, int num_clks,
-			      struct clk_bulk_data *clks)
+static int __clk_bulk_get(struct device *dev, int num_clks,
+			  struct clk_bulk_data *clks, bool optional)
 {
 	int ret;
 	int i;
@@ -88,10 +88,14 @@ int __must_check clk_bulk_get(struct device *dev, int num_clks,
 		clks[i].clk = clk_get(dev, clks[i].id);
 		if (IS_ERR(clks[i].clk)) {
 			ret = PTR_ERR(clks[i].clk);
+			clks[i].clk = NULL;
+
+			if (ret == -ENOENT && optional)
+				continue;
+
 			if (ret != -EPROBE_DEFER)
 				dev_err(dev, "Failed to get clk '%s': %d\n",
 					clks[i].id, ret);
-			clks[i].clk = NULL;
 			goto err;
 		}
 	}
@@ -103,8 +107,21 @@ int __must_check clk_bulk_get(struct device *dev, int num_clks,
 
 	return ret;
 }
+
+int __must_check clk_bulk_get(struct device *dev, int num_clks,
+			      struct clk_bulk_data *clks)
+{
+	return __clk_bulk_get(dev, num_clks, clks, false);
+}
 EXPORT_SYMBOL(clk_bulk_get);
 
+int __must_check clk_bulk_get_optional(struct device *dev, int num_clks,
+				       struct clk_bulk_data *clks)
+{
+	return __clk_bulk_get(dev, num_clks, clks, true);
+}
+EXPORT_SYMBOL_GPL(clk_bulk_get_optional);
+
 void clk_bulk_put_all(int num_clks, struct clk_bulk_data *clks)
 {
 	if (IS_ERR_OR_NULL(clks))

include/linux/clk.h

@@ -332,6 +332,19 @@ int __must_check clk_bulk_get(struct device *dev, int num_clks,
  */
 int __must_check clk_bulk_get_all(struct device *dev,
 				  struct clk_bulk_data **clks);
+
+/**
+ * clk_bulk_get_optional - lookup and obtain a number of references to clock producer
+ * @dev: device for clock "consumer"
+ * @num_clks: the number of clk_bulk_data
+ * @clks: the clk_bulk_data table of consumer
+ *
+ * Behaves the same as clk_bulk_get() except where there is no clock producer.
+ * In this case, instead of returning -ENOENT, the function returns 0 and
+ * NULL for a clk for which a clock producer could not be determined.
+ */
+int __must_check clk_bulk_get_optional(struct device *dev, int num_clks,
+				       struct clk_bulk_data *clks);
 /**
  * devm_clk_bulk_get - managed get multiple clk consumers
  * @dev: device for clock "consumer"
@@ -718,6 +731,12 @@ static inline int __must_check clk_bulk_get(struct device *dev, int num_clks,
 	return 0;
 }
 
+static inline int __must_check clk_bulk_get_optional(struct device *dev,
+				int num_clks, struct clk_bulk_data *clks)
+{
+	return 0;
+}
+
 static inline int __must_check clk_bulk_get_all(struct device *dev,
 					 struct clk_bulk_data **clks)
 {