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

Although most of USB devices are hot-plug's, there are still some devices
are hard wired on the board, eg, for HSIC and SSIC interface USB devices.
If these kinds of USB devices are multiple functions, and they can supply
other interfaces like i2c, gpios for other devices, we may need to
descirbe these at device tree.

In this commit, it uses "reg" in dts as port number to match the port
number decided by USB core, if they are the same, then the device node
is for the device we are creating for USB core.

Signed-off-by: Peter Chen <redacted>
---
 .../devicetree/bindings/usb/usb-device.txt         |  8 ++++
 drivers/usb/core/Makefile                          |  2 +-
 drivers/usb/core/of.c                              | 48 ++++++++++++++++++++++
 drivers/usb/core/usb.c                             |  8 +++-
 include/linux/usb.h                                |  2 +
 include/linux/usb/of.h                             |  6 +++
 6 files changed, 71 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/usb/usb-device.txt
 create mode 100644 drivers/usb/core/of.c

diff --git a/Documentation/devicetree/bindings/usb/usb-device.txt b/Documentation/devicetree/bindings/usb/usb-device.txt
new file mode 100644
index 0000000..d35facd
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/usb-device.txt

@@ -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.

diff --git a/drivers/usb/core/Makefile b/drivers/usb/core/Makefile
index 2f6f932..9780877 100644
--- a/drivers/usb/core/Makefile
+++ b/drivers/usb/core/Makefile

@@ -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

diff --git a/drivers/usb/core/of.c b/drivers/usb/core/of.c
new file mode 100644
index 0000000..008ae6a
--- /dev/null
+++ b/drivers/usb/core/of.c

@@ -0,0 +1,48 @@
+/*
+ * of.c                The helpers for hcd device tree support
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
+ *
+ * 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;