[RFC PATCH 1/2] USB: core: let USB device know device node

@@ -0,0 +1,8 @@
+Generic USB Device Properties
+
+Usually, we only use device tree for hard wired USB device. 
+The reference binding doc is from:
+http://playground.sun.com/1275/bindings/usb/usb-1_0.ps.
+
+Required properties:
+- reg: the port number which this device is connecting to.

@@ -5,7 +5,7 @@
 usbcore-y := usb.o hub.o hcd.o urb.o message.o driver.o
 usbcore-y += config.o file.o buffer.o sysfs.o endpoint.o
 usbcore-y += devio.o notify.o generic.o quirks.o devices.o
-usbcore-y += port.o
+usbcore-y += port.o of.o
 
 usbcore-$(CONFIG_PCI)		+= hcd-pci.o
 usbcore-$(CONFIG_ACPI)		+= usb-acpi.o

@@ -0,0 +1,48 @@
+/*
+ * of.c		The helpers for hcd device tree support
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@freescale.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+
+/**
+ * usb_of_find_node - Find the device node match port number
+ * @dev: the parent device node
+ * @portnum: the port number which device is connecting 
+ *
+ * Find the node from device tree according to its port number.
+ *
+ * Return: On success, a pointer to the device node, %NULL on failure.
+ */
+struct device_node *usb_of_find_node(struct device_node *parent, int portnum)
+{
+	struct device_node *node;
+	u32 port;
+
+	for_each_child_of_node(parent, node) {
+		if (!of_property_read_u32(node, "reg", &port)) {
+			if (port == portnum)
+				return node;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(usb_of_find_node);
+

@@ -36,6 +36,7 @@
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/debugfs.h>
+#include <linux/usb/of.h>
 
 #include <asm/io.h>
 #include <linux/scatterlist.h>

@@ -502,11 +503,14 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 	dev->connect_time = jiffies;
 	dev->active_duration = -jiffies;
 #endif
-	if (root_hub)	/* Root hub always ok [and always wired] */
+	if (root_hub) {	/* Root hub always ok [and always wired] */
 		dev->authorized = 1;
-	else {
+		dev->of_node = bus->controller->of_node;
+	} else {
 		dev->authorized = !!HCD_DEV_AUTHORIZED(usb_hcd);
 		dev->wusb = usb_bus_is_wusb(bus) ? 1 : 0;
+		dev->dev.of_node = usb_of_find_node
+			(parent->of_node, dev->portnum);
 	}
 	return dev;
 }

@@ -21,6 +21,7 @@
 #include <linux/sched.h>	/* for current && schedule_timeout */
 #include <linux/mutex.h>	/* for struct mutex */
 #include <linux/pm_runtime.h>	/* for runtime PM */
+#include <linux/of.h>		/* for device tree */
 
 struct usb_device;
 struct usb_driver;

@@ -616,6 +617,7 @@ struct usb_device {
 	struct usb3_lpm_parameters u1_params;
 	struct usb3_lpm_parameters u2_params;
 	unsigned lpm_disable_count;
+	struct device_node	*of_node; /* associated device tree node */
 };
 #define	to_usb_device(d) container_of(d, struct usb_device, dev)
 

@@ -16,6 +16,7 @@ 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);
+struct device_node *usb_of_find_node(struct device_node *parent, int portnum);
 #else
 static inline enum usb_dr_mode
 of_usb_get_dr_mode_by_phy(struct device_node *phy_np)

@@ -31,6 +32,11 @@ static inline int of_usb_update_otg_caps(struct device_node *np,
 {
 	return 0;
 }
+struct inline device_node *usb_of_find_node(struct device_node *parent,
+				int portnum)
+{
+	return NULL;
+}
 #endif
 
 #if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_USB_SUPPORT)