[PATCH 20/24] reset: add support for reset_control_status

[Ahmad Fatoum]

Driver code may want to query status of a reset line. Add an optional
callback for drivers to provide this.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 drivers/reset/core.c             | 21 +++++++++++++++++++++
 drivers/reset/reset-simple.c     |  3 ++-
 include/linux/reset-controller.h |  2 ++
 include/linux/reset.h            |  6 ++++++
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 17deb3fa8fc3..4355c3415eb0 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -81,6 +81,27 @@ void reset_controller_unregister(struct reset_controller_dev *rcdev)
 }
 EXPORT_SYMBOL_GPL(reset_controller_unregister);
 
+/**
+ * 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 or if the desc is NULL (optional reset).
+ * @rstc: reset controller
+ */
+int reset_control_status(struct reset_control *rstc)
+{
+	if (!rstc)
+		return 0;
+
+	if (WARN_ON(IS_ERR(rstc)))
+		return -EINVAL;
+
+	if (rstc->rcdev->ops->status)
+		return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL_GPL(reset_control_status);
+
 /**
  * reset_control_reset - reset the controlled device
  * @rstc: reset controller
diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
index 082956d94dae..9db00f64f438 100644
--- a/drivers/reset/reset-simple.c
+++ b/drivers/reset/reset-simple.c
@@ -75,7 +75,7 @@ static int reset_simple_reset(struct reset_controller_dev *rcdev,
 	return reset_simple_deassert(rcdev, id);
 }
 
-static int __maybe_unused reset_simple_status(struct reset_controller_dev *rcdev,
+static int reset_simple_status(struct reset_controller_dev *rcdev,
 					      unsigned long id)
 {
 	struct reset_simple_data *data = to_reset_simple_data(rcdev);
@@ -93,6 +93,7 @@ const struct reset_control_ops reset_simple_ops = {
 	.assert		= reset_simple_assert,
 	.deassert	= reset_simple_deassert,
 	.reset		= reset_simple_reset,
+	.status		= reset_simple_status,
 };
 EXPORT_SYMBOL_GPL(reset_simple_ops);
 
diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h
index 8ace8cd41794..a9047e947e93 100644
--- a/include/linux/reset-controller.h
+++ b/include/linux/reset-controller.h
@@ -14,11 +14,13 @@ struct reset_controller_dev;
  *         things to reset the device
  * @assert: manually assert the reset line, if supported
  * @deassert: manually deassert the reset line, if supported
+ * @status: return the status of the reset line, if supported
  */
 struct reset_control_ops {
 	int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
 	int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
 	int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
+	int (*status)(struct reset_controller_dev *rcdev, unsigned long id);
 };
 
 struct device_node;
diff --git a/include/linux/reset.h b/include/linux/reset.h
index d25464d4bd60..d0677b1d9f63 100644
--- a/include/linux/reset.h
+++ b/include/linux/reset.h
@@ -8,6 +8,7 @@ struct reset_control;
 
 #ifdef CONFIG_RESET_CONTROLLER
 
+int reset_control_status(struct reset_control *rstc);
 int reset_control_reset(struct reset_control *rstc);
 int reset_control_assert(struct reset_control *rstc);
 int reset_control_deassert(struct reset_control *rstc);
@@ -25,6 +26,11 @@ int __must_check device_reset_all(struct device_d *dev);
 
 #else
 
+static inline int reset_control_status(struct reset_control *rstc)
+{
+	return 0;
+}
+
 static inline int reset_control_reset(struct reset_control *rstc)
 {
 	return 0;
-- 
2.30.2