[PATCH] USB: add <linux/usb_otg.h>

Hardware implementing USB-OTG needs to use an OTG controller and/or
transceiver driver to switch the Mini-AB connector between the host
and peripheral side controller drivers (and the USB device role
supported by that driver).

This patch adds a simple "otg_transceiver" interface that can abstract
implementation details for that port, as needed for some upcoming patches:

    - Neither host nor peripheral controller drivers need to know about
      how the OTG controller is implemented.  Example: is the transceiver
      internal?  If not, which external chip?

    - The OTG controller doesn't need to know if the Host Controller
      is OHCI, EHCI, or something custom ... all it knows is that the
      HCD looks like a "usb_bus".

    - In the same way, the peripheral controller is just a "usb_gadget".

One implementation of this will be posted soon; the interface is by
no means cast in stone, other implementations may need to morph this
interface a bit.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

include/linux/usb_otg.h

+// include/linux/usb_otg.h 
+
+/*
+ * These APIs may be used between USB controllers.  USB device drivers
+ * (for either host or peripheral roles) don't use these calls; they
+ * continue to use just usb_device and usb_gadget.
+ */
+
+
+/* OTG defines lots of enumeration states before device reset */
+enum usb_otg_state {
+	OTG_STATE_UNDEFINED = 0,
+
+	/* single-role peripheral, and dual-role default-b */
+	OTG_STATE_B_IDLE,
+	OTG_STATE_B_SRP_INIT,
+	OTG_STATE_B_PERIPHERAL,
+
+	/* extra dual-role default-b states */
+	OTG_STATE_B_WAIT_ACON,
+	OTG_STATE_B_HOST,
+
+	/* dual-role default-a */
+	OTG_STATE_A_IDLE,
+	OTG_STATE_A_WAIT_VRISE,
+	OTG_STATE_A_WAIT_BCON,
+	OTG_STATE_A_HOST,
+	OTG_STATE_A_SUSPEND,
+	OTG_STATE_A_PERIPHERAL,
+	OTG_STATE_A_WAIT_VFALL,
+	OTG_STATE_A_VBUS_ERR,
+};
+
+/*
+ * the otg driver needs to interact with both device side and host side
+ * usb controllers.  it decides which controller is active at a given
+ * moment, using the transceiver, ID signal, HNP and sometimes static
+ * configuration information (including "board isn't wired for otg").
+ */
+struct otg_transceiver {
+	struct device		*dev;
+	const char		*label;
+
+	u8			default_a;
+	enum usb_otg_state	state;
+
+	struct usb_bus		*host;
+	struct usb_gadget	*gadget;
+
+	/* to pass extra port status to the root hub */
+	u16			port_status;
+	u16			port_change;
+
+	/* bind/unbind the host controller */
+	int 	(*set_host)(struct otg_transceiver *otg,
+				struct usb_bus *host);
+
+	/* bind/unbind the peripheral controller */
+	int	(*set_peripheral)(struct otg_transceiver *otg,
+				struct usb_gadget *gadget);
+
+	/* effective for B devices, ignored for A-peripheral */
+	int	(*set_power)(struct otg_transceiver *otg,
+				unsigned mA);
+
+	/* for B devices only:  start session with A-Host */
+	int	(*start_srp)(struct otg_transceiver *otg);
+
+	/* start or continue HNP role switch */
+	int	(*start_hnp)(struct otg_transceiver *otg);
+
+};
+
+
+/* for board-specific init logic */
+extern int otg_set_transceiver(struct otg_transceiver *);
+
+
+/* for usb host and peripheral controller drivers */
+extern struct otg_transceiver *otg_get_transceiver(void);
+
+static inline int
+otg_start_hnp(struct otg_transceiver *otg)
+{
+	return otg->start_hnp(otg);
+}
+
+
+/* for HCDs */
+static inline int
+otg_set_host(struct otg_transceiver *otg, struct usb_bus *host)
+{
+	return otg->set_host(otg, host);
+}
+
+
+/* for usb peripheral controller drivers */
+static inline int
+otg_set_peripheral(struct otg_transceiver *otg, struct usb_gadget *periph)
+{
+	return otg->set_peripheral(otg, periph);
+}
+
+static inline int
+otg_set_power(struct otg_transceiver *otg, unsigned mA)
+{
+	return otg->set_power(otg, mA);
+}
+
+static inline int
+otg_start_srp(struct otg_transceiver *otg)
+{
+	return otg->start_srp(otg);
+}
+
+