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, 57 insertions, 28 deletions

diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index c665219..f8751ff 100644
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -37,8 +37,9 @@
  * one (!) network link through the USB gadget stack, normally "usb0".
  *
  * The control and data models are handled by the function driver which
- * connects to this code; such as CDC Ethernet, "CDC Subset", or RNDIS.
- * That includes all descriptor and endpoint management.
+ * connects to this code; such as CDC Ethernet (ECM or EEM),
+ * "CDC Subset", or RNDIS.  That includes all descriptor and endpoint
+ * management.
  *
  * Link level addressing is handled by this component using module
  * parameters; if no such parameters are provided, random link level
@@ -68,9 +69,13 @@ struct eth_dev {
 	struct list_head	tx_reqs, rx_reqs;
 	atomic_t		tx_qlen;
 
+	struct sk_buff_head	rx_frames;
+
 	unsigned		header_len;
-	struct sk_buff		*(*wrap)(struct sk_buff *skb);
-	int			(*unwrap)(struct sk_buff *skb);
+	struct sk_buff		*(*wrap)(struct gether *, struct sk_buff *skb);
+	int			(*unwrap)(struct gether *,
+						struct sk_buff *skb,
+						struct sk_buff_head *list);
 
 	struct work_struct	work;
 
@@ -269,7 +274,7 @@ enomem:
 
 static void rx_complete(struct usb_ep *ep, struct usb_request *req)
 {
-	struct sk_buff	*skb = req->context;
+	struct sk_buff	*skb = req->context, *skb2;
 	struct eth_dev	*dev = ep->driver_data;
 	int		status = req->status;
 
@@ -278,26 +283,47 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
 	/* normal completion */
 	case 0:
 		skb_put(skb, req->actual);
-		if (dev->unwrap)
-			status = dev->unwrap(skb);
-		if (status < 0
-				|| ETH_HLEN > skb->len
-				|| skb->len > ETH_FRAME_LEN) {
-			dev->net->stats.rx_errors++;
-			dev->net->stats.rx_length_errors++;
-			DBG(dev, "rx length %d\n", skb->len);
-			break;
-		}
 
-		skb->protocol = eth_type_trans(skb, dev->net);
-		dev->net->stats.rx_packets++;
-		dev->net->stats.rx_bytes += skb->len;
+		if (dev->unwrap) {
+			unsigned long	flags;
 
-		/* no buffer copies needed, unless hardware can't
-		 * use skb buffers.
-		 */
-		status = netif_rx(skb);
+			spin_lock_irqsave(&dev->lock, flags);
+			if (dev->port_usb) {
+				status = dev->unwrap(dev->port_usb,
+							skb,
+							&dev->rx_frames);
+			} else {
+				dev_kfree_skb_any(skb);
+				status = -ENOTCONN;
+			}
+			spin_unlock_irqrestore(&dev->lock, flags);
+		} else {
+			skb_queue_tail(&dev->rx_frames, skb);
+		}
 		skb = NULL;
+
+		skb2 = skb_dequeue(&dev->rx_frames);
+		while (skb2) {
+			if (status < 0
+					|| ETH_HLEN > skb2->len
+					|| skb2->len > ETH_FRAME_LEN) {
+				dev->net->stats.rx_errors++;
+				dev->net->stats.rx_length_errors++;
+				DBG(dev, "rx length %d\n", skb2->len);
+				dev_kfree_skb_any(skb2);
+				goto next_frame;
+			}
+			skb2->protocol = eth_type_trans(skb2, dev->net);
+			dev->net->stats.rx_packets++;
+			dev->net->stats.rx_bytes += skb2->len;
+
+			/* no buffer copies needed, unless hardware can't
+			 * use skb buffers.
+			 */
+			status = netif_rx(skb2);
+next_frame:
+			skb2 = skb_dequeue(&dev->rx_frames);
+		}
 		break;
 
 	/* software-driven interface shutdown */
@@ -537,14 +563,15 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
 	 * or there's not enough space for extra headers we need
 	 */
 	if (dev->wrap) {
-		struct sk_buff	*skb_new;
+		unsigned long	flags;
 
-		skb_new = dev->wrap(skb);
-		if (!skb_new)
+		spin_lock_irqsave(&dev->lock, flags);
+		if (dev->port_usb)
+			skb = dev->wrap(dev->port_usb, skb);
+		spin_unlock_irqrestore(&dev->lock, flags);
+		if (!skb)
 			goto drop;
 
-		dev_kfree_skb_any(skb);
-		skb = skb_new;
 		length = skb->len;
 	}
 	req->buf = skb->data;
@@ -578,9 +605,9 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
 	}
 
 	if (retval) {
+		dev_kfree_skb_any(skb);
 drop:
 		dev->net->stats.tx_dropped++;
-		dev_kfree_skb_any(skb);
 		spin_lock_irqsave(&dev->req_lock, flags);
 		if (list_empty(&dev->tx_reqs))
 			netif_start_queue(net);
@@ -753,6 +780,8 @@ int __init gether_setup(struct usb_gadget *g, u8 ethaddr[ETH_ALEN])
 	INIT_LIST_HEAD(&dev->tx_reqs);
 	INIT_LIST_HEAD(&dev->rx_reqs);
 
+	skb_queue_head_init(&dev->rx_frames);
+
 	/* network device setup */
 	dev->net = net;
 	strcpy(net->name, "usb%d");