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, 23 insertions, 0 deletions

diff --git a/drivers/usb/gadget/gadget_chips.h b/drivers/usb/gadget/gadget_chips.h
index ca5149ea731..5246e8fef2b 100644
--- a/drivers/usb/gadget/gadget_chips.h
+++ b/drivers/usb/gadget/gadget_chips.h
@@ -214,3 +214,26 @@ static inline int usb_gadget_controller_number(struct usb_gadget *gadget)
 		return 0x21;
 	return -ENOENT;
 }
+
+
+/**
+ * gadget_supports_altsettings - return true if altsettings work
+ * @gadget: the gadget in question
+ */
+static inline bool gadget_supports_altsettings(struct usb_gadget *gadget)
+{
+	/* PXA 21x/25x/26x has no altsettings at all */
+	if (gadget_is_pxa(gadget))
+		return false;
+
+	/* PXA 27x and 3xx have *broken* altsetting support */
+	if (gadget_is_pxa27x(gadget))
+		return false;
+
+	/* SH3 hardware just doesn't do altsettings */
+	if (gadget_is_sh(gadget))
+		return false;
+
+	/* Everything else is *presumably* fine ... */
+	return true;
+}