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>

1 files changed, 28 insertions, 3 deletions

diff --git a/drivers/usb/gadget/ether.c b/drivers/usb/gadget/ether.c
index bd102f5052ba..f37de283d0ab 100644
--- a/drivers/usb/gadget/ether.c
+++ b/drivers/usb/gadget/ether.c
@@ -61,6 +61,11 @@
  * simpler, Microsoft pushes their own approach: RNDIS.  The published
  * RNDIS specs are ambiguous and appear to be incomplete, and are also
  * needlessly complex.  They borrow more from CDC ACM than CDC ECM.
+ *
+ * While CDC ECM, CDC Subset, and RNDIS are designed to extend the ethernet
+ * interface to the target, CDC EEM was designed to use ethernet over the USB
+ * link between the host and target.  CDC EEM is implemented as an alternative
+ * to those other protocols when that communication model is more appropriate
  */
 
 #define DRIVER_DESC             "Ethernet Gadget"
@@ -114,6 +119,7 @@ static inline bool has_rndis(void)
 #include "f_rndis.c"
 #include "rndis.c"
 #endif
+#include "f_eem.c"
 #include "u_ether.c"
 
 /*-------------------------------------------------------------------------*/
@@ -150,6 +156,10 @@ static inline bool has_rndis(void)
 #define RNDIS_VENDOR_NUM        0x0525  /* NetChip */
 #define RNDIS_PRODUCT_NUM       0xa4a2  /* Ethernet/RNDIS Gadget */
 
+/* For EEM gadgets */
+#define EEM_VENDOR_NUM  0x0525  /* INVALID - NEEDS TO BE ALLOCATED */
+#define EEM_PRODUCT_NUM 0xa4a1  /* INVALID - NEEDS TO BE ALLOCATED */
+
 /*-------------------------------------------------------------------------*/
 
 static struct usb_device_descriptor device_desc = {
@@ -246,8 +256,16 @@ static struct usb_configuration rndis_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
+#ifdef CONFIG_USB_ETH_EEM
+static int use_eem = 1;
+#else
+static int use_eem;
+#endif
+module_param(use_eem, bool, 0);
+MODULE_PARM_DESC(use_eem, "use CDC EEM mode");
+
 /*
- * We _always_ have an ECM or CDC Subset configuration.
+ * We _always_ have an ECM, CDC Subset, or EEM configuration.
  */
 static int __init eth_do_config(struct usb_configuration *c)
 {
@@ -258,7 +276,9 @@ static int __init eth_do_config(struct usb_configuration *c)
                 c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
         }
 
-        if (can_support_ecm(c->cdev->gadget))
+        if (use_eem)
+                return eem_bind_config(c);
+        else if (can_support_ecm(c->cdev->gadget))
                 return ecm_bind_config(c, hostaddr);
         else
                 return geth_bind_config(c, hostaddr);
@@ -286,7 +306,12 @@ static int __init eth_bind(struct usb_composite_dev *cdev)
                 return status;
 
         /* set up main config label and device descriptor */
-        if (can_support_ecm(cdev->gadget)) {
+        if (use_eem) {
+                /* EEM */
+                eth_config_driver.label = "CDC Ethernet (EEM)";
+                device_desc.idVendor = cpu_to_le16(EEM_VENDOR_NUM);
+                device_desc.idProduct = cpu_to_le16(EEM_PRODUCT_NUM);
+        } else if (can_support_ecm(cdev->gadget)) {
                 /* ECM */
                 eth_config_driver.label = "CDC Ethernet (ECM)";
         } else {