usb: of: add an api to get dr_mode by the phy node

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@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

2 files changed, 59 insertions, 6 deletions

diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
index 673d53038ed2..e6ec125e4485 100644
--- a/drivers/usb/common/common.c
+++ b/drivers/usb/common/common.c
@@ -17,6 +17,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/of.h>
 #include <linux/usb/otg.h>
+#include <linux/of_platform.h>
 
 const char *usb_otg_state_string(enum usb_otg_state state)
 {
@@ -106,25 +107,72 @@ static const char *const usb_dr_modes[] = {
         [USB_DR_MODE_OTG]               = "otg",
 };
 
+static enum usb_dr_mode usb_get_dr_mode_from_string(const char *str)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(usb_dr_modes); i++)
+                if (!strcmp(usb_dr_modes[i], str))
+                        return i;
+
+        return USB_DR_MODE_UNKNOWN;
+}
+
 enum usb_dr_mode usb_get_dr_mode(struct device *dev)
 {
         const char *dr_mode;
-        int err, i;
+        int err;
 
         err = device_property_read_string(dev, "dr_mode", &dr_mode);
         if (err < 0)
                 return USB_DR_MODE_UNKNOWN;
 
-        for (i = 0; i < ARRAY_SIZE(usb_dr_modes); i++)
-                if (!strcmp(dr_mode, usb_dr_modes[i]))
-                        return i;
-
-        return USB_DR_MODE_UNKNOWN;
+        return usb_get_dr_mode_from_string(dr_mode);
 }
 EXPORT_SYMBOL_GPL(usb_get_dr_mode);
 
 #ifdef CONFIG_OF
 /**
+ * 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;
+        const char *dr_mode;
+        int index;
+        int err;
+
+        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:
+        err = of_property_read_string(controller, "dr_mode", &dr_mode);
+        of_node_put(controller);
+
+        if (err < 0)
+                return USB_DR_MODE_UNKNOWN;
+
+        return usb_get_dr_mode_from_string(dr_mode);
+}
+EXPORT_SYMBOL_GPL(of_usb_get_dr_mode_by_phy);
+
+/**
  * of_usb_host_tpl_support - to get if Targeted Peripheral List is supported
  * for given targeted hosts (non-PC hosts)
  * @np: Pointer to the given device_node
diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
index c3fe9e48ce27..3805757dcdc2 100644
--- a/include/linux/usb/of.h
+++ b/include/linux/usb/of.h
@@ -12,10 +12,15 @@
 #include <linux/usb/phy.h>
 
 #if IS_ENABLED(CONFIG_OF)
+enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *phy_np);
 bool of_usb_host_tpl_support(struct device_node *np);
 int of_usb_update_otg_caps(struct device_node *np,
                         struct usb_otg_caps *otg_caps);
 #else
+enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *phy_np)
+{
+        return USB_DR_MODE_UNKNOWN;
+}
 static inline bool of_usb_host_tpl_support(struct device_node *np)
 {
         return false;