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
describe these at device tree.

In this commit, it uses "reg" in dts as physical port number to match
the phyiscal 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 <peter.chen@freescale.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/usb-device.txt

@@ -0,0 +1,28 @@
+Generic USB Device Properties
+
+Usually, we only use device tree for hard wired USB device.
+The reference binding doc is from:
+http://www.firmware.org/1275/bindings/usb/usb-1_0.ps
+
+Required properties:
+- compatible: usbVID,PID. The textual representation of VID, PID shall
+  be in lower case hexadecimal with leading zeroes suppressed. The
+  other compatible strings from the above standard binding could also
+  be used, but a device adhering to this binding may leave out all except
+  for usbVID,PID.
+- reg: the port number which this device is connecting to, the range
+  is 1-31.
+
+Example:
+
+&usb1 {
+	status = "okay";
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	hub: genesys@1 {
+		compatible = "usb5e3,608";
+		reg = <1>;
+	};
+}

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

drivers/usb/core/of.c

@@ -0,0 +1,47 @@
+/*
+ * 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/of.h>
+
+/**
+ * usb_of_get_child_node - Find the device node match port number
+ * @parent: 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_get_child_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_get_child_node);
+

drivers/usb/core/usb.c

@@ -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>
@@ -470,6 +471,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 		dev->route = 0;
 
 		dev->dev.parent = bus->controller;
+		dev->dev.of_node = bus->controller->of_node;
 		dev_set_name(&dev->dev, "usb%d", bus->busnum);
 		root_hub = 1;
 	} else {
@@ -494,6 +496,14 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 		dev->dev.parent = &parent->dev;
 		dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
 
+		if (!parent->parent) {
+			/* device under root hub's port */
+			port1 = usb_hcd_find_raw_port_number(usb_hcd,
+				port1);
+		}
+		dev->dev.of_node = usb_of_get_child_node(parent->dev.of_node,
+				port1);
+
 		/* hub driver sets up TT records */
 	}
 

include/linux/usb/of.h

@@ -16,6 +16,8 @@ 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_get_child_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 +33,11 @@ static inline int of_usb_update_otg_caps(struct device_node *np,
 {
 	return 0;
 }
+static inline struct device_node *usb_of_get_child_node
+		(struct device_node *parent, int portnum)
+{
+	return NULL;
+}
 #endif
 
 #if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_USB_SUPPORT)