[PATCH v4] usb: of: add an api to get dr_mode by the phy node

[Bin Liu <b-liu@xxxxxx>]

Some USB phy drivers have different handling for the controller in each
dr_mode. But the phy driver does not have visibility to the dr_mode of
the controller.

This adds an api to return the dr_mode of the controller which
associates the given phy node.

Signed-off-by: Bin Liu <b-liu@xxxxxx>
---
v4: - iterating all phy nodes in the associated controller
    - add of_node_put() to decrement refcount

v3: search controller node from dt root, as the phy and controller nodes
    might not have the same parent.

v2: move drivers/usb/phy/phy-am335x.c changes into patch 3/3.

 drivers/usb/common/common.c | 36 ++++++++++++++++++++++++++++++++++++
 include/linux/usb/of.h      |  6 ++++++
 2 files changed, 42 insertions(+)

diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
index b530fd4..e3da800 100644
--- a/drivers/usb/common/common.c
+++ b/drivers/usb/common/common.c
@@ -114,6 +114,42 @@ enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np)
 EXPORT_SYMBOL_GPL(of_usb_get_dr_mode);
 
 /**
+ * of_usb_get_dr_mode_by_phy - Get dual role mode for the controller device
+ * which is associated with the given phy device_node
+ * @np:	Pointer to the given phy device_node
+ *
+ * In dts a usb controller associates with phy devices.  The function gets
+ * the string from property 'dr_mode' of the controller associated with the
+ * given phy device node, and returns the correspondig enum usb_dr_mode.
+ */
+enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *phy_np)
+{
+	struct device_node *controller = NULL;
+	struct device_node *phy;
+	enum usb_dr_mode dr_mode;
+	int index;
+
+	do {
+		controller = of_find_node_with_property(controller, "phys");
+		index = 0;
+		do {
+			phy = of_parse_phandle(controller, "phys", index);
+			of_node_put(phy);
+			if (phy == phy_np)
+				goto finish;
+			index++;
+		} while (phy);
+	} while (controller);
+
+finish:
+	dr_mode = of_usb_get_dr_mode(controller);
+	of_node_put(controller);
+
+	return dr_mode;
+}
+EXPORT_SYMBOL_GPL(of_usb_get_dr_mode_by_phy);
+
+/**
  * of_usb_get_maximum_speed - Get maximum requested speed for a given USB
  * controller.
  * @np: Pointer to the given device_node
diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
index cfe0528..14ebd5a 100644
--- a/include/linux/usb/of.h
+++ b/include/linux/usb/of.h
@@ -13,6 +13,7 @@
 
 #if IS_ENABLED(CONFIG_OF)
 enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np);
+enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *phy_np);
 enum usb_device_speed of_usb_get_maximum_speed(struct device_node *np);
 bool of_usb_host_tpl_support(struct device_node *np);
 #else
@@ -21,6 +22,11 @@ static inline enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np)
 	return USB_DR_MODE_UNKNOWN;
 }
 
+enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *phy_np)
+{
+	return USB_DR_MODE_UNKNOWN;
+}
+
 static inline enum usb_device_speed
 of_usb_get_maximum_speed(struct device_node *np)
 {
-- 
1.8.4

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