USB: gadget: Add EEM gadget driver
This patch adds a CDC EEM ethernet gadget driver. CDC EEM is a newer
USB ethernet specification that uses a simpler interface than the older
CDC ECM. This makes CDC EEM usable by a wider set of USB hardware.
By default the ethernet gadget will still use CDC ECM/Subset, but kernel
configuration and/or a module parameter will allow alternative use of
the CDC EEM protocol.
Changes since last version:
- Brought in missing RNDIS changes that caused compile error
- Modified 'sentinel CRC' checking to match EEM host driver
Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 3537d91..4d8ab47 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -628,8 +628,8 @@
tristate "Ethernet Gadget (with CDC Ethernet support)"
depends on NET
help
- This driver implements Ethernet style communication, in either
- of two ways:
+ This driver implements Ethernet style communication, in one of
+ several ways:
- The "Communication Device Class" (CDC) Ethernet Control Model.
That protocol is often avoided with pure Ethernet adapters, in
@@ -639,7 +639,11 @@
- On hardware can't implement that protocol, a simple CDC subset
is used, placing fewer demands on USB.
- RNDIS support is a third option, more demanding than that subset.
+ - CDC Ethernet Emulation Model (EEM) is a newer standard that has
+ a simpler interface that can be used by more USB hardware.
+
+ RNDIS support is an additional option, more demanding than than
+ subset.
Within the USB device, this gadget driver exposes a network device
"usbX", where X depends on what other networking devices you have.
@@ -672,6 +676,22 @@
XP, you'll need to download drivers from Microsoft's website; a URL
is given in comments found in that info file.
+config USB_ETH_EEM
+ bool "Ethernet Emulation Model (EEM) support"
+ depends on USB_ETH
+ default n
+ help
+ CDC EEM is a newer USB standard that is somewhat simpler than CDC ECM
+ and therefore can be supported by more hardware. Technically ECM and
+ EEM are designed for different applications. The ECM model extends
+ the network interface to the target (e.g. a USB cable modem), and the
+ EEM model is for mobile devices to communicate with hosts using
+ ethernet over USB. For Linux gadgets, however, the interface with
+ the host is the same (a usbX device), so the differences are minimal.
+
+ If you say "y" here, the Ethernet gadget driver will use the EEM
+ protocol rather than ECM. If unsure, say "n".
+
config USB_GADGETFS
tristate "Gadget Filesystem (EXPERIMENTAL)"
depends on EXPERIMENTAL