[net-next,v2,2/2] usbnet: ipheth: add CDC NCM support

diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
index 8875a3d0e..6677ac700 100644
--- a/drivers/net/usb/ipheth.c
+++ b/drivers/net/usb/ipheth.c
@@ -52,6 +52,7 @@ 
 #include <linux/ethtool.h>
 #include <linux/usb.h>
 #include <linux/workqueue.h>
+#include <linux/usb/cdc.h>
 
 #define USB_VENDOR_APPLE        0x05ac
 
@@ -59,8 +60,11 @@ 
 #define IPHETH_USBINTF_SUBCLASS 253
 #define IPHETH_USBINTF_PROTO    1
 
-#define IPHETH_BUF_SIZE         1514
 #define IPHETH_IP_ALIGN		2	/* padding at front of URB */
+#define IPHETH_NCM_HEADER_SIZE  (12 + 96) /* NCMH + NCM0 */
+#define IPHETH_TX_BUF_SIZE      ETH_FRAME_LEN
+#define IPHETH_RX_BUF_SIZE      65536
+
 #define IPHETH_TX_TIMEOUT       (5 * HZ)
 
 #define IPHETH_INTFNUM          2
@@ -71,6 +75,7 @@ 
 #define IPHETH_CTRL_TIMEOUT     (5 * HZ)
 
 #define IPHETH_CMD_GET_MACADDR   0x00
+#define IPHETH_CMD_ENABLE_NCM    0x04
 #define IPHETH_CMD_CARRIER_CHECK 0x45
 
 #define IPHETH_CARRIER_CHECK_TIMEOUT round_jiffies_relative(1 * HZ)
@@ -84,6 +89,8 @@  static const struct usb_device_id ipheth_table[] = {
 };
 MODULE_DEVICE_TABLE(usb, ipheth_table);
 
+static const char ipheth_start_packet[] = { 0x00, 0x01, 0x01, 0x00 };
+
 struct ipheth_device {
 	struct usb_device *udev;
 	struct usb_interface *intf;
@@ -97,6 +104,7 @@  struct ipheth_device {
 	u8 bulk_out;
 	struct delayed_work carrier_work;
 	bool confirmed_pairing;
+	int (*rcvbulk_callback)(struct urb *urb);
 };
 
 static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags);
@@ -116,12 +124,12 @@  static int ipheth_alloc_urbs(struct ipheth_device *iphone)
 	if (rx_urb == NULL)
 		goto free_tx_urb;
 
-	tx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE,
+	tx_buf = usb_alloc_coherent(iphone->udev, IPHETH_TX_BUF_SIZE,
 				    GFP_KERNEL, &tx_urb->transfer_dma);
 	if (tx_buf == NULL)
 		goto free_rx_urb;
 
-	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
+	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_RX_BUF_SIZE,
 				    GFP_KERNEL, &rx_urb->transfer_dma);
 	if (rx_buf == NULL)
 		goto free_tx_buf;
@@ -134,7 +142,7 @@  static int ipheth_alloc_urbs(struct ipheth_device *iphone)
 	return 0;
 
 free_tx_buf:
-	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, tx_buf,
+	usb_free_coherent(iphone->udev, IPHETH_TX_BUF_SIZE, tx_buf,
 			  tx_urb->transfer_dma);
 free_rx_urb:
 	usb_free_urb(rx_urb);
@@ -146,9 +154,9 @@  static int ipheth_alloc_urbs(struct ipheth_device *iphone)
 
 static void ipheth_free_urbs(struct ipheth_device *iphone)
 {
-	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN, iphone->rx_buf,
+	usb_free_coherent(iphone->udev, IPHETH_RX_BUF_SIZE, iphone->rx_buf,
 			  iphone->rx_urb->transfer_dma);
-	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->tx_buf,
+	usb_free_coherent(iphone->udev, IPHETH_TX_BUF_SIZE, iphone->tx_buf,
 			  iphone->tx_urb->transfer_dma);
 	usb_free_urb(iphone->rx_urb);
 	usb_free_urb(iphone->tx_urb);
@@ -160,14 +168,105 @@  static void ipheth_kill_urbs(struct ipheth_device *dev)
 	usb_kill_urb(dev->rx_urb);
 }
 
-static void ipheth_rcvbulk_callback(struct urb *urb)
+static int ipheth_consume_skb(char *buf, int len, struct ipheth_device *dev)
 {
-	struct ipheth_device *dev;
 	struct sk_buff *skb;
-	int status;
+
+	skb = dev_alloc_skb(len);
+	if (!skb) {
+		dev->net->stats.rx_dropped++;
+		return -ENOMEM;
+	}
+
+	skb_put_data(skb, buf, len);
+	skb->dev = dev->net;
+	skb->protocol = eth_type_trans(skb, dev->net);
+
+	dev->net->stats.rx_packets++;
+	dev->net->stats.rx_bytes += len;
+	netif_rx(skb);
+
+	return 0;
+}
+
+static int ipheth_rcvbulk_callback_legacy(struct urb *urb)
+{
+	struct ipheth_device *dev;
 	char *buf;
 	int len;
 
+	dev = urb->context;
+
+	if (urb->actual_length <= IPHETH_IP_ALIGN) {
+		dev->net->stats.rx_length_errors++;
+		return -EINVAL;
+	}
+	len = urb->actual_length - IPHETH_IP_ALIGN;
+	buf = urb->transfer_buffer + IPHETH_IP_ALIGN;
+
+	return ipheth_consume_skb(buf, len, dev);
+}
+
+static int ipheth_rcvbulk_callback_ncm(struct urb *urb)
+{
+	struct usb_cdc_ncm_nth16 *ncmh;
+	struct usb_cdc_ncm_ndp16 *ncm0;
+	struct usb_cdc_ncm_dpe16 *dpe;
+	struct ipheth_device *dev;
+	int retval = -EINVAL;
+	char *buf;
+	int len;
+
+	dev = urb->context;
+
+	if (urb->actual_length < IPHETH_NCM_HEADER_SIZE) {
+		dev->net->stats.rx_length_errors++;
+		return retval;
+	}
+
+	ncmh = urb->transfer_buffer;
+	if (ncmh->dwSignature != cpu_to_le32(USB_CDC_NCM_NTH16_SIGN) ||
+	    le16_to_cpu(ncmh->wNdpIndex) >= urb->actual_length) {
+		dev->net->stats.rx_errors++;
+		return retval;
+	}
+
+	ncm0 = urb->transfer_buffer + le16_to_cpu(ncmh->wNdpIndex);
+	if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN) ||
+	    le16_to_cpu(ncmh->wHeaderLength) + le16_to_cpu(ncm0->wLength) >=
+	    urb->actual_length) {
+		dev->net->stats.rx_errors++;
+		return retval;
+	}
+
+	dpe = ncm0->dpe16;
+	while (le16_to_cpu(dpe->wDatagramIndex) != 0 &&
+	       le16_to_cpu(dpe->wDatagramLength) != 0) {
+		if (le16_to_cpu(dpe->wDatagramIndex) >= urb->actual_length ||
+		    le16_to_cpu(dpe->wDatagramIndex) +
+		    le16_to_cpu(dpe->wDatagramLength) > urb->actual_length) {
+			dev->net->stats.rx_length_errors++;
+			return retval;
+		}
+
+		buf = urb->transfer_buffer + le16_to_cpu(dpe->wDatagramIndex);
+		len = le16_to_cpu(dpe->wDatagramLength);
+
+		retval = ipheth_consume_skb(buf, len, dev);
+		if (retval != 0)
+			return retval;
+
+		dpe++;
+	}
+
+	return 0;
+}
+
+static void ipheth_rcvbulk_callback(struct urb *urb)
+{
+	struct ipheth_device *dev;
+	int retval, status;
+
 	dev = urb->context;
 	if (dev == NULL)
 		return;
@@ -187,29 +286,25 @@  static void ipheth_rcvbulk_callback(struct urb *urb)
 		return;
 	}
 
-	if (urb->actual_length <= IPHETH_IP_ALIGN) {
-		dev->net->stats.rx_length_errors++;
-		return;
-	}
-	len = urb->actual_length - IPHETH_IP_ALIGN;
-	buf = urb->transfer_buffer + IPHETH_IP_ALIGN;
-
-	skb = dev_alloc_skb(len);
-	if (!skb) {
-		dev_err(&dev->intf->dev, "%s: dev_alloc_skb: -ENOMEM\n",
-			__func__);
-		dev->net->stats.rx_dropped++;
+	/* The very first frame we receive from device has a fixed 4-byte value
+	 * We can safely skip it
+	 */
+	if (unlikely
+		(urb->actual_length == sizeof(ipheth_start_packet) &&
+		 memcmp(urb->transfer_buffer, ipheth_start_packet,
+			sizeof(ipheth_start_packet)) == 0
+	))
+		goto rx_submit;
+
+	retval = dev->rcvbulk_callback(urb);
+	if (retval != 0) {
+		dev_err(&dev->intf->dev, "%s: callback retval: %d\n",
+			__func__, retval);
 		return;
 	}
 
-	skb_put_data(skb, buf, len);
-	skb->dev = dev->net;
-	skb->protocol = eth_type_trans(skb, dev->net);
-
-	dev->net->stats.rx_packets++;
-	dev->net->stats.rx_bytes += len;
+rx_submit:
 	dev->confirmed_pairing = true;
-	netif_rx(skb);
 	ipheth_rx_submit(dev, GFP_ATOMIC);
 }
 
@@ -310,6 +405,27 @@  static int ipheth_get_macaddr(struct ipheth_device *dev)
 	return retval;
 }
 
+static int ipheth_enable_ncm(struct ipheth_device *dev)
+{
+	struct usb_device *udev = dev->udev;
+	int retval;
+
+	retval = usb_control_msg(udev,
+				 usb_sndctrlpipe(udev, IPHETH_CTRL_ENDP),
+				 IPHETH_CMD_ENABLE_NCM, /* request */
+				 0x40, /* request type */
+				 0x00, /* value */
+				 0x02, /* index */
+				 NULL,
+				 0,
+				 IPHETH_CTRL_TIMEOUT);
+
+	dev_info(&dev->intf->dev, "%s: usb_control_msg: %d\n",
+		 __func__, retval);
+
+	return retval;
+}
+
 static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags)
 {
 	struct usb_device *udev = dev->udev;
@@ -317,7 +433,7 @@  static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags)
 
 	usb_fill_bulk_urb(dev->rx_urb, udev,
 			  usb_rcvbulkpipe(udev, dev->bulk_in),
-			  dev->rx_buf, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
+			  dev->rx_buf, IPHETH_RX_BUF_SIZE,
 			  ipheth_rcvbulk_callback,
 			  dev);
 	dev->rx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
@@ -365,7 +481,7 @@  static netdev_tx_t ipheth_tx(struct sk_buff *skb, struct net_device *net)
 	int retval;
 
 	/* Paranoid */
-	if (skb->len > IPHETH_BUF_SIZE) {
+	if (skb->len > IPHETH_TX_BUF_SIZE) {
 		WARN(1, "%s: skb too large: %d bytes\n", __func__, skb->len);
 		dev->net->stats.tx_dropped++;
 		dev_kfree_skb_any(skb);
@@ -373,12 +489,10 @@  static netdev_tx_t ipheth_tx(struct sk_buff *skb, struct net_device *net)
 	}
 
 	memcpy(dev->tx_buf, skb->data, skb->len);
-	if (skb->len < IPHETH_BUF_SIZE)
-		memset(dev->tx_buf + skb->len, 0, IPHETH_BUF_SIZE - skb->len);
 
 	usb_fill_bulk_urb(dev->tx_urb, udev,
 			  usb_sndbulkpipe(udev, dev->bulk_out),
-			  dev->tx_buf, IPHETH_BUF_SIZE,
+			  dev->tx_buf, skb->len,
 			  ipheth_sndbulk_callback,
 			  dev);
 	dev->tx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
@@ -450,6 +564,7 @@  static int ipheth_probe(struct usb_interface *intf,
 	dev->net = netdev;
 	dev->intf = intf;
 	dev->confirmed_pairing = false;
+	dev->rcvbulk_callback = ipheth_rcvbulk_callback_legacy;
 	/* Set up endpoints */
 	hintf = usb_altnum_to_altsetting(intf, IPHETH_ALT_INTFNUM);
 	if (hintf == NULL) {
@@ -481,6 +596,10 @@  static int ipheth_probe(struct usb_interface *intf,
 	if (retval)
 		goto err_get_macaddr;
 
+	retval = ipheth_enable_ncm(dev);
+	if (!retval)
+		dev->rcvbulk_callback = ipheth_rcvbulk_callback_ncm;
+
 	INIT_DELAYED_WORK(&dev->carrier_work, ipheth_carrier_check_work);
 
 	retval = ipheth_alloc_urbs(dev);