USB: add device-tree support for interfaces

Add OF device-tree support for USB interfaces.

USB "interface nodes" are children of USB "device nodes" and are
identified by an interface number and a configuration value:

	&usb1 { /* host controller */
		dev1: device@1 { /* device at port 1 */
			compatible = "usb1234,5678";
			reg = <1>;

			#address-cells = <2>;
			#size-cells = <0>;

			interface@0,2 { /* interface 0 of configuration 2 */
				compatible = "usbif1234,5678.config2.0";
				reg = <0 2>;
			};
		};
	};

The configuration component is not included in the textual
representation of an interface-node unit address for configuration 1:

	&dev1 {
		interface@0 {	/* interface 0 of configuration 1 */
			compatible = "usbif1234,5678.config1.0";
			reg = <0 1>;
		};
	};

When a USB device of class 0 or 9 (hub) has only a single configuration
with a single interface, a special case "combined node" is used instead
of a device node with an interface node:

	&usb1 {
		device@2 {
			compatible = "usb1234,abcd";
			reg = <2>;
		};
	};

Combined nodes are shared by the two device structures representing the
USB device and its interface in the kernel's device model.

Note that, as for device nodes, the compatible strings for interface
nodes are currently not used.

For more details see "Open Firmware Recommended Practice: Universal
Serial Bus Version 1" and the binding documentation.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
index 6cbe7a5c2b57..0294ccac4f1d 100644
--- a/include/linux/usb/of.h
+++ b/include/linux/usb/of.h
@@ -12,6 +12,8 @@
 #include <linux/usb/otg.h>
 #include <linux/usb/phy.h>
 
+struct usb_device;
+
 #if IS_ENABLED(CONFIG_OF)
 enum usb_dr_mode of_usb_get_dr_mode_by_phy(struct device_node *np, int arg0);
 bool of_usb_host_tpl_support(struct device_node *np);
@@ -19,6 +21,9 @@ 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);
+bool usb_of_has_combined_node(struct usb_device *udev);
+struct device_node *usb_of_get_interface_node(struct usb_device *udev,
+		u8 config, u8 ifnum);
 struct device *usb_of_get_companion_dev(struct device *dev);
 #else
 static inline enum usb_dr_mode
@@ -40,6 +45,15 @@ static inline struct device_node *usb_of_get_child_node
 {
 	return NULL;
 }
+static inline bool usb_of_has_combined_node(struct usb_device *udev)
+{
+	return false;
+}
+static inline struct device_node *
+usb_of_get_interface_node(struct usb_device *udev, u8 config, u8 ifnum)
+{
+	return NULL;
+}
 static inline struct device *usb_of_get_companion_dev(struct device *dev)
 {
 	return NULL;