usb ethernet gadget: split CDC Ethernet function

This is a "CDC Ethernet" (ECM) function driver, extracted from the
all-in-one Ethernet gadget driver.

This is a good example of how to implement interface altsettings.
In fact it's currently the only such example in the gadget stack,
pending addition of OBEX support.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/usb/gadget/u_ether.h b/drivers/usb/gadget/u_ether.h
index 0ef823447f28..8abf197ab402 100644
--- a/drivers/usb/gadget/u_ether.h
+++ b/drivers/usb/gadget/u_ether.h
@@ -28,6 +28,9 @@
 #include <linux/usb/composite.h>
 #include <linux/usb/cdc.h>
 
+#include "gadget_chips.h"
+
+
 /*
  * This represents the USB side of an "ethernet" link, managed by a USB
  * function which provides control and (maybe) framing.  Two functions
@@ -80,7 +83,28 @@ void gether_cleanup(void);
 struct net_device *gether_connect(struct gether *);
 void gether_disconnect(struct gether *);
 
+/* Some controllers can't support CDC Ethernet (ECM) ... */
+static inline bool can_support_ecm(struct usb_gadget *gadget)
+{
+        if (!gadget_supports_altsettings(gadget))
+                return false;
+
+        /* SA1100 can do ECM, *without* status endpoint ... but we'll
+         * only use it in non-ECM mode for backwards compatibility
+         * (and since we currently require a status endpoint)
+         */
+        if (gadget_is_sa1100(gadget))
+                return false;
+
+        /* Everything else is *presumably* fine ... but this is a bit
+         * chancy, so be **CERTAIN** there are no hardware issues with
+         * your controller.  Add it above if it can't handle CDC.
+         */
+        return true;
+}
+
 /* each configuration may bind one instance of an ethernet link */
 int geth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
+int ecm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
 
 #endif /* __U_ETHER_H */