linux-kernel - [PATCH] reset: Make optional functions really optional.

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Date:   Thu, 15 Dec 2016 18:05:50 +0000
From:   Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
To:     p.zabel@...gutronix.de, linux-kernel@...r.kernel.org
Cc:     laurent.pinchart@...asonboard.com, CARLOS.PALMINHA@...opsys.com,
        Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
Subject: [PATCH] reset: Make optional functions really optional.

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@...opsys.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