[PATCH] reset: Make optional functions really optional.

[Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>]

Up until now optional functions in the reset API were similar to the non
optional.

This patch corrects that, while maintaining compatibility with existing
drivers.

As suggested here: https://lkml.org/lkml/2016/12/14/502

Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
---
 drivers/reset/core.c  | 21 +++++++++++++++++++--
 include/linux/reset.h | 46 ++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 395dc9c..6150e7c 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -135,9 +135,14 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register);
  * @rstc: reset controller
  *
  * Calling this on a shared reset controller is an error.
+ *
+ * If it's an optional reset it will return 0.
  */
 int reset_control_reset(struct reset_control *rstc)
 {
+	if (!rstc)
+		return 0;
+
 	if (WARN_ON(rstc->shared))
 		return -EINVAL;
 
@@ -158,9 +163,14 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
  *
  * For shared reset controls a driver cannot expect the hw's registers and
  * internal state to be reset, but must be prepared for this to happen.
+ *
+ * If it's an optional reset it will return 0.
  */
 int reset_control_assert(struct reset_control *rstc)
 {
+	if (!rstc)
+		return 0;
+
 	if (!rstc->rcdev->ops->assert)
 		return -ENOTSUPP;
 
@@ -180,10 +190,14 @@ EXPORT_SYMBOL_GPL(reset_control_assert);
  * reset_control_deassert - deasserts the reset line
  * @rstc: reset controller
  *
- * After calling this function, the reset is guaranteed to be deasserted.
+ * After calling this function, the reset is guaranteed to be deasserted, if
+ * it's not optional.
  */
 int reset_control_deassert(struct reset_control *rstc)
 {
+	if (!rstc)
+		return 0;
+
 	if (!rstc->rcdev->ops->deassert)
 		return -ENOTSUPP;
 
@@ -199,11 +213,14 @@ EXPORT_SYMBOL_GPL(reset_control_deassert);
 /**
  * reset_control_status - returns a negative errno if not supported, a
  * positive value if the reset line is asserted, or zero if the reset
- * line is not asserted.
+ * line is not asserted or if the desc is NULL (optional reset).
  * @rstc: reset controller
  */
 int reset_control_status(struct reset_control *rstc)
 {
+	if (!rstc)
+		return 0;
+
 	if (rstc->rcdev->ops->status)
 		return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
 
diff --git a/include/linux/reset.h b/include/linux/reset.h
index 5daff15..1af1e62 100644
--- a/include/linux/reset.h
+++ b/include/linux/reset.h
@@ -138,13 +138,33 @@ static inline struct reset_control *reset_control_get_shared(
 static inline struct reset_control *reset_control_get_optional_exclusive(
 					struct device *dev, const char *id)
 {
-	return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
+	struct reset_control *desc;
+
+	desc = __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
+
+	if (IS_ERR(desc)) {
+		if (PTR_ERR(desc) == -ENOENT)
+			return NULL;
+	}
+
+	return desc;
+
 }
 
 static inline struct reset_control *reset_control_get_optional_shared(
 					struct device *dev, const char *id)
 {
-	return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1);
+
+	struct reset_control *desc;
+
+	desc = __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1);
+
+	if (IS_ERR(desc)) {
+		if (PTR_ERR(desc) == -ENOENT)
+			return NULL;
+	}
+
+	return desc;
 }
 
 /**
@@ -273,13 +293,31 @@ static inline struct reset_control *devm_reset_control_get_shared(
 static inline struct reset_control *devm_reset_control_get_optional_exclusive(
 					struct device *dev, const char *id)
 {
-	return __devm_reset_control_get(dev, id, 0, 0);
+	struct reset_control *desc;
+
+	desc = __devm_reset_control_get(dev, id, 0, 0);
+
+	if (IS_ERR(desc)) {
+		if (PTR_ERR(desc) == -ENOENT)
+			return NULL;
+	}
+
+	return desc;
 }
 
 static inline struct reset_control *devm_reset_control_get_optional_shared(
 					struct device *dev, const char *id)
 {
-	return __devm_reset_control_get(dev, id, 0, 1);
+	struct reset_control *desc;
+
+	desc = __devm_reset_control_get(dev, id, 0, 1);
+
+	if (IS_ERR(desc)) {
+		if (PTR_ERR(desc) == -ENOENT)
+			return NULL;
+	}
+
+	return desc;
 }
 
 /**
-- 
2.10.2