usb: Add "portX/connect_type" attribute to expose usb port's connect type

Some platforms provide usb port connect types through ACPI. This
patch is to add this new attribute to expose these information
to user space.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-usb

@@ -227,3 +227,12 @@ Contact:	Lan Tianyu <tianyu.lan@intel.com>
 Description:
 		The /sys/bus/usb/devices/.../(hub interface)/portX
 		is usb port device's sysfs directory.
+
+What:		/sys/bus/usb/devices/.../(hub interface)/portX/connect_type
+Date:		January 2013
+Contact:	Lan Tianyu <tianyu.lan@intel.com>
+Description:
+		Some platforms provide usb port connect types through ACPI.
+		This attribute is to expose these information to user space.
+		The file will read "hotplug", "wired" and "not used" if the
+		information is available, and "unknown" otherwise.

drivers/usb/core/port.c

@@ -20,6 +20,48 @@
 
 #include "hub.h"
 
+static const struct attribute_group *port_dev_group[];
+
+static ssize_t show_port_connect_type(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct usb_port *port_dev = to_usb_port(dev);
+	char *result;
+
+	switch (port_dev->connect_type) {
+	case USB_PORT_CONNECT_TYPE_HOT_PLUG:
+		result = "hotplug";
+		break;
+	case USB_PORT_CONNECT_TYPE_HARD_WIRED:
+		result = "hardwired";
+		break;
+	case USB_PORT_NOT_USED:
+		result = "not used";
+		break;
+	default:
+		result = "unknown";
+		break;
+	}
+
+	return sprintf(buf, "%s\n", result);
+}
+static DEVICE_ATTR(connect_type, S_IRUGO, show_port_connect_type,
+		NULL);
+
+static struct attribute *port_dev_attrs[] = {
+	&dev_attr_connect_type.attr,
+	NULL,
+};
+
+static struct attribute_group port_dev_attr_grp = {
+	.attrs = port_dev_attrs,
+};
+
+static const struct attribute_group *port_dev_group[] = {
+	&port_dev_attr_grp,
+	NULL,
+};
+
 static void usb_port_device_release(struct device *dev)
 {
 	struct usb_port *port_dev = to_usb_port(dev);
@@ -45,6 +87,7 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1)
 
 	hub->ports[port1 - 1] = port_dev;
 	port_dev->dev.parent = hub->intfdev;
+	port_dev->dev.groups = port_dev_group;
 	port_dev->dev.type = &usb_port_device_type;
 	dev_set_name(&port_dev->dev, "port%d", port1);