[ecm] Add support for CDC-ECM USB Ethernet devices

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/ecm.c

@@ -21,8 +21,11 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <stdint.h>
 #include <errno.h>
+#include <ipxe/netdevice.h>
+#include <ipxe/ethernet.h>
 #include <ipxe/if_ether.h>
 #include <ipxe/base16.h>
+#include <ipxe/profile.h>
 #include <ipxe/usb.h>
 #include "ecm.h"
 
@@ -32,6 +35,29 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  */
 
+/** Refill profiler */
+static struct profiler ecm_refill_profiler __profiler =
+	{ .name = "ecm.refill" };
+
+/** Interrupt completion profiler */
+static struct profiler ecm_intr_profiler __profiler =
+	{ .name = "ecm.intr" };
+
+/** Bulk IN completion profiler */
+static struct profiler ecm_in_profiler __profiler =
+	{ .name = "ecm.in" };
+
+/** Bulk OUT profiler */
+static struct profiler ecm_out_profiler __profiler =
+	{ .name = "ecm.out" };
+
+/******************************************************************************
+ *
+ * Ethernet functional descriptor
+ *
+ ******************************************************************************
+ */
+
 /**
  * Locate Ethernet functional descriptor
  *
@@ -87,3 +113,634 @@ int ecm_fetch_mac ( struct usb_device *usb,
 
 	return 0;
 }
+
+/******************************************************************************
+ *
+ * Ring management
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Transcribe receive ring name (for debugging)
+ *
+ * @v ecm		CDC-ECM device
+ * @v ring		Receive ring
+ * @ret name		Receive ring name
+ */
+static inline const char * ecm_rx_name ( struct ecm_device *ecm,
+					 struct ecm_rx_ring *ring ) {
+	if ( ring == &ecm->intr ) {
+		return "interrupt";
+	} else if ( ring == &ecm->in ) {
+		return "bulk IN";
+	} else {
+		return "UNKNOWN";
+	}
+}
+
+/**
+ * Refill receive ring
+ *
+ * @v ecm		CDC-ECM device
+ * @v ring		Receive ring
+ */
+static void ecm_rx_refill ( struct ecm_device *ecm, struct ecm_rx_ring *ring ) {
+	struct net_device *netdev = ecm->netdev;
+	struct io_buffer *iobuf;
+	int rc;
+
+	/* Refill ring */
+	while ( ring->fill < ring->max ) {
+
+		/* Profile refill */
+		profile_start ( &ecm_refill_profiler );
+
+		/* Allocate I/O buffer */
+		iobuf = alloc_iob ( ring->mtu );
+		if ( ! iobuf ) {
+			/* Wait for next refill */
+			break;
+		}
+		iob_put ( iobuf, ring->mtu );
+
+		/* Enqueue I/O buffer */
+		if ( ( rc = usb_stream ( &ring->ep, iobuf, 0 ) ) != 0 ) {
+			netdev_rx_err ( netdev, iob_disown ( iobuf ), rc );
+			break;
+		}
+
+		/* Increment fill level */
+		ring->fill++;
+		profile_stop ( &ecm_refill_profiler );
+	}
+}
+
+/******************************************************************************
+ *
+ * CDC-ECM communications interface
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Complete interrupt transfer
+ *
+ * @v ep		USB endpoint
+ * @v iobuf		I/O buffer
+ * @v rc		Completion status code
+ */
+static void ecm_intr_complete ( struct usb_endpoint *ep,
+				struct io_buffer *iobuf, int rc ) {
+	struct ecm_device *ecm = container_of ( ep, struct ecm_device, intr.ep);
+	struct net_device *netdev = ecm->netdev;
+	struct usb_setup_packet *message;
+	size_t len = iob_len ( iobuf );
+
+	/* Profile completions */
+	profile_start ( &ecm_intr_profiler );
+
+	/* Decrement fill level */
+	assert ( ecm->intr.fill > 0 );
+	ecm->intr.fill--;
+
+	/* Ignore packets cancelled when the endpoint closes */
+	if ( ! ep->open )
+		goto ignore;
+
+	/* Drop packets with errors */
+	if ( rc != 0 ) {
+		DBGC ( ecm, "ECM %p interrupt failed: %s\n",
+		       ecm, strerror ( rc ) );
+		DBGC_HDA ( ecm, 0, iobuf->data, iob_len ( iobuf ) );
+		goto error;
+	}
+
+	/* Extract message header */
+	if ( len < sizeof ( *message ) ) {
+		DBGC ( ecm, "ECM %p underlength interrupt:\n", ecm );
+		DBGC_HDA ( ecm, 0, iobuf->data, iob_len ( iobuf ) );
+		goto error;
+	}
+	message = iobuf->data;
+
+	/* Parse message header */
+	switch ( message->request ) {
+
+	case cpu_to_le16 ( CDC_NETWORK_CONNECTION ) :
+		if ( message->value && ! netdev_link_ok ( netdev ) ) {
+			DBGC ( ecm, "ECM %p link up\n", ecm );
+			netdev_link_up ( netdev );
+		} else if ( netdev_link_ok ( netdev ) && ! message->value ) {
+			DBGC ( ecm, "ECM %p link down\n", ecm );
+			netdev_link_down ( netdev );
+		}
+		break;
+
+	case cpu_to_le16 ( CDC_CONNECTION_SPEED_CHANGE ) :
+		/* Ignore */
+		break;
+
+	default:
+		DBGC ( ecm, "ECM %p unrecognised interrupt:\n", ecm );
+		DBGC_HDA ( ecm, 0, iobuf->data, iob_len ( iobuf ) );
+		goto error;
+	}
+
+	/* Free I/O buffer */
+	free_iob ( iobuf );
+	profile_stop ( &ecm_intr_profiler );
+
+	return;
+
+ error:
+	netdev_rx_err ( netdev, iob_disown ( iobuf ), rc );
+ ignore:
+	free_iob ( iobuf );
+	return;
+}
+
+/** Interrupt endpoint operations */
+static struct usb_endpoint_driver_operations ecm_intr_operations = {
+	.complete = ecm_intr_complete,
+};
+
+/**
+ * Open communications interface
+ *
+ * @v ecm		CDC-ECM device
+ * @ret rc		Return status code
+ */
+static int ecm_comms_open ( struct ecm_device *ecm ) {
+	int rc;
+
+	/* Open interrupt endpoint */
+	if ( ( rc = usb_endpoint_open ( &ecm->intr.ep ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not open interrupt: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_open;
+	}
+
+	/* Refill interrupt ring */
+	ecm_rx_refill ( ecm, &ecm->intr );
+
+	return 0;
+
+	usb_endpoint_close ( &ecm->intr.ep );
+	assert ( ecm->intr.fill == 0 );
+ err_open:
+	return rc;
+}
+
+/**
+ * Close communications interface
+ *
+ * @v ecm		CDC-ECM device
+ */
+static void ecm_comms_close ( struct ecm_device *ecm ) {
+
+	/* Close interrupt endpoint */
+	usb_endpoint_close ( &ecm->intr.ep );
+	assert ( ecm->intr.fill == 0 );
+}
+
+/******************************************************************************
+ *
+ * CDC-ECM data interface
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Complete bulk IN transfer
+ *
+ * @v ep		USB endpoint
+ * @v iobuf		I/O buffer
+ * @v rc		Completion status code
+ */
+static void ecm_in_complete ( struct usb_endpoint *ep, struct io_buffer *iobuf,
+			      int rc ) {
+	struct ecm_device *ecm = container_of ( ep, struct ecm_device, in.ep );
+	struct net_device *netdev = ecm->netdev;
+
+	/* Profile receive completions */
+	profile_start ( &ecm_in_profiler );
+
+	/* Decrement fill level */
+	assert ( ecm->in.fill > 0 );
+	ecm->in.fill--;
+
+	/* Ignore packets cancelled when the endpoint closes */
+	if ( ! ep->open )
+		goto ignore;
+
+	/* Record USB errors against the network device */
+	if ( rc != 0 ) {
+		DBGC ( ecm, "ECM %p bulk IN failed: %s\n",
+		       ecm, strerror ( rc ) );
+		goto error;
+	}
+
+	/* Hand off to network stack */
+	netdev_rx ( netdev, iob_disown ( iobuf ) );
+
+	profile_stop ( &ecm_in_profiler );
+	return;
+
+ error:
+	netdev_rx_err ( netdev, iob_disown ( iobuf ), rc );
+ ignore:
+	free_iob ( iobuf );
+}
+
+/** Bulk IN endpoint operations */
+static struct usb_endpoint_driver_operations ecm_in_operations = {
+	.complete = ecm_in_complete,
+};
+
+/**
+ * Transmit packet
+ *
+ * @v ecm		CDC-ECM device
+ * @v iobuf		I/O buffer
+ * @ret rc		Return status code
+ */
+static int ecm_out_transmit ( struct ecm_device *ecm,
+			      struct io_buffer *iobuf ) {
+	int rc;
+
+	/* Profile transmissions */
+	profile_start ( &ecm_out_profiler );
+
+	/* Enqueue I/O buffer */
+	if ( ( rc = usb_stream ( &ecm->out.ep, iobuf, 1 ) ) != 0 )
+		return rc;
+
+	profile_stop ( &ecm_out_profiler );
+	return 0;
+}
+
+/**
+ * Complete bulk OUT transfer
+ *
+ * @v ep		USB endpoint
+ * @v iobuf		I/O buffer
+ * @v rc		Completion status code
+ */
+static void ecm_out_complete ( struct usb_endpoint *ep, struct io_buffer *iobuf,
+			       int rc ) {
+	struct ecm_device *ecm = container_of ( ep, struct ecm_device, out.ep );
+	struct net_device *netdev = ecm->netdev;
+
+	/* Report TX completion */
+	netdev_tx_complete_err ( netdev, iobuf, rc );
+}
+
+/** Bulk OUT endpoint operations */
+static struct usb_endpoint_driver_operations ecm_out_operations = {
+	.complete = ecm_out_complete,
+};
+
+/**
+ * Open data interface
+ *
+ * @v ecm		CDC-ECM device
+ * @ret rc		Return status code
+ */
+static int ecm_data_open ( struct ecm_device *ecm ) {
+	struct usb_device *usb = ecm->usb;
+	int rc;
+
+	/* Select alternate setting for data interface */
+	if ( ( rc = usb_set_interface ( usb, ecm->data,
+					ECM_DATA_ALTERNATE ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not set alternate interface: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_set_interface;
+	}
+
+	/* Open bulk IN endpoint */
+	if ( ( rc = usb_endpoint_open ( &ecm->in.ep ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not open bulk IN: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_open_in;
+	}
+
+	/* Open bulk OUT endpoint */
+	if ( ( rc = usb_endpoint_open ( &ecm->out.ep ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not open bulk OUT: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_open_out;
+	}
+
+	/* Refill bulk IN ring */
+	ecm_rx_refill ( ecm, &ecm->in );
+
+	return 0;
+
+	usb_endpoint_close ( &ecm->out.ep );
+ err_open_out:
+	usb_endpoint_close ( &ecm->in.ep );
+	assert ( ecm->in.fill == 0 );
+ err_open_in:
+	usb_set_interface ( usb, ecm->data, 0 );
+ err_set_interface:
+	return rc;
+}
+
+/**
+ * Close data interface
+ *
+ * @v ecm		CDC-ECM device
+ */
+static void ecm_data_close ( struct ecm_device *ecm ) {
+	struct usb_device *usb = ecm->usb;
+
+	/* Close endpoints */
+	usb_endpoint_close ( &ecm->out.ep );
+	usb_endpoint_close ( &ecm->in.ep );
+	assert ( ecm->in.fill == 0 );
+
+	/* Reset data interface */
+	usb_set_interface ( usb, ecm->data, 0 );
+}
+
+/******************************************************************************
+ *
+ * Network device interface
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Open network device
+ *
+ * @v netdev		Network device
+ * @ret rc		Return status code
+ */
+static int ecm_open ( struct net_device *netdev ) {
+	struct ecm_device *ecm = netdev->priv;
+	struct usb_device *usb = ecm->usb;
+	unsigned int filter;
+	int rc;
+
+	/* Open communications interface */
+	if ( ( rc = ecm_comms_open ( ecm ) ) != 0 )
+		goto err_comms_open;
+
+	/* Open data interface */
+	if ( ( rc = ecm_data_open ( ecm ) ) != 0 )
+		goto err_data_open;
+
+	/* Set packet filter */
+	filter = ( ECM_PACKET_TYPE_PROMISCUOUS |
+		   ECM_PACKET_TYPE_ALL_MULTICAST |
+		   ECM_PACKET_TYPE_DIRECTED |
+		   ECM_PACKET_TYPE_BROADCAST );
+	if ( ( rc = usb_control ( usb, ECM_SET_ETHERNET_PACKET_FILTER,
+				  filter, ecm->comms, NULL, 0 ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not set packet filter: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_set_filter;
+	}
+
+	return 0;
+
+ err_set_filter:
+	ecm_data_close ( ecm );
+ err_data_open:
+	ecm_comms_close ( ecm );
+ err_comms_open:
+	return rc;
+}
+
+/**
+ * Close network device
+ *
+ * @v netdev		Network device
+ */
+static void ecm_close ( struct net_device *netdev ) {
+	struct ecm_device *ecm = netdev->priv;
+
+	/* Close data interface */
+	ecm_data_close ( ecm );
+
+	/* Close communications interface */
+	ecm_comms_close ( ecm );
+}
+
+/**
+ * Transmit packet
+ *
+ * @v netdev		Network device
+ * @v iobuf		I/O buffer
+ * @ret rc		Return status code
+ */
+static int ecm_transmit ( struct net_device *netdev,
+			  struct io_buffer *iobuf ) {
+	struct ecm_device *ecm = netdev->priv;
+	int rc;
+
+	/* Transmit packet */
+	if ( ( rc = ecm_out_transmit ( ecm, iobuf ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/**
+ * Poll for completed and received packets
+ *
+ * @v netdev		Network device
+ */
+static void ecm_poll ( struct net_device *netdev ) {
+	struct ecm_device *ecm = netdev->priv;
+
+	/* Poll USB bus */
+	usb_poll ( ecm->bus );
+
+	/* Refill interrupt ring */
+	ecm_rx_refill ( ecm, &ecm->intr );
+
+	/* Refill bulk IN ring */
+	ecm_rx_refill ( ecm, &ecm->in );
+}
+
+/** CDC-ECM network device operations */
+static struct net_device_operations ecm_operations = {
+	.open		= ecm_open,
+	.close		= ecm_close,
+	.transmit	= ecm_transmit,
+	.poll		= ecm_poll,
+};
+
+/******************************************************************************
+ *
+ * USB interface
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Probe device
+ *
+ * @v func		USB function
+ * @v config		Configuration descriptor
+ * @ret rc		Return status code
+ */
+static int ecm_probe ( struct usb_function *func,
+		       struct usb_configuration_descriptor *config ) {
+	struct usb_device *usb = func->usb;
+	struct net_device *netdev;
+	struct ecm_device *ecm;
+	struct usb_interface_descriptor *comms;
+	struct usb_interface_descriptor *data;
+	struct ecm_ethernet_descriptor *ethernet;
+	int rc;
+
+	/* Allocate and initialise structure */
+	netdev = alloc_etherdev ( sizeof ( *ecm ) );
+	if ( ! netdev ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	netdev_init ( netdev, &ecm_operations );
+	netdev->dev = &func->dev;
+	ecm = netdev->priv;
+	memset ( ecm, 0, sizeof ( *ecm ) );
+	ecm->usb = usb;
+	ecm->bus = usb->port->hub->bus;
+	ecm->netdev = netdev;
+	usb_endpoint_init ( &ecm->intr.ep, usb, &ecm_intr_operations );
+	usb_endpoint_init ( &ecm->in.ep, usb, &ecm_in_operations );
+	usb_endpoint_init ( &ecm->out.ep, usb, &ecm_out_operations );
+	DBGC ( ecm, "ECM %p on %s\n", ecm, func->name );
+
+	/* Identify interfaces */
+	if ( func->count < ECM_INTERFACE_COUNT ) {
+		DBGC ( ecm, "ECM %p has only %d interfaces\n",
+		       ecm, func->count );
+		rc = -EINVAL;
+		goto err_count;
+	}
+	ecm->comms = func->interface[ECM_INTERFACE_COMMS];
+	ecm->data = func->interface[ECM_INTERFACE_DATA];
+
+	/* Locate communications interface descriptor */
+	comms = usb_interface_descriptor ( config, ecm->comms, 0 );
+	if ( ! comms ) {
+		DBGC ( ecm, "ECM %p has no communications interface\n", ecm );
+		rc = -EINVAL;
+		goto err_comms;
+	}
+
+	/* Locate data interface descriptor */
+	data = usb_interface_descriptor ( config, ecm->data,
+					  ECM_DATA_ALTERNATE );
+	if ( ! data ) {
+		DBGC ( ecm, "ECM %p has no data interface\n", ecm );
+		rc = -EINVAL;
+		goto err_data;
+	}
+
+	/* Describe interrupt endpoint */
+	if ( ( rc = usb_endpoint_described ( &ecm->intr.ep, config, comms,
+					     USB_INTERRUPT, 0 ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not describe interrupt endpoint: "
+		       "%s\n", ecm, strerror ( rc ) );
+		goto err_interrupt;
+	}
+	ecm->intr.mtu = ecm->intr.ep.mtu;
+	ecm->intr.max = ECM_INTR_MAX_FILL;
+
+	/* Describe bulk IN endpoint */
+	if ( ( rc = usb_endpoint_described ( &ecm->in.ep, config, data,
+					     USB_BULK_IN, 0 ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not describe bulk IN endpoint: "
+		       "%s\n", ecm, strerror ( rc ) );
+		goto err_bulk_in;
+	}
+	ecm->in.mtu = ECM_IN_MTU;
+	ecm->in.max = ECM_IN_MAX_FILL;
+
+	/* Describe bulk OUT endpoint */
+	if ( ( rc = usb_endpoint_described ( &ecm->out.ep, config, data,
+					     USB_BULK_OUT, 0 ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not describe bulk OUT endpoint: "
+		       "%s\n", ecm, strerror ( rc ) );
+		goto err_bulk_out;
+	}
+
+	/* Locate Ethernet descriptor */
+	ethernet = ecm_ethernet_descriptor ( config, comms );
+	if ( ! ethernet ) {
+		DBGC ( ecm, "ECM %p has no Ethernet descriptor\n", ecm );
+		rc = -EINVAL;
+		goto err_ethernet;
+	}
+
+	/* Fetch MAC address */
+	if ( ( rc = ecm_fetch_mac ( usb, ethernet, netdev->hw_addr ) ) != 0 ) {
+		DBGC ( ecm, "ECM %p could not fetch MAC address: %s\n",
+		       ecm, strerror ( rc ) );
+		goto err_fetch_mac;
+	}
+
+	/* Register network device */
+	if ( ( rc = register_netdev ( netdev ) ) != 0 )
+		goto err_register;
+
+	usb_func_set_drvdata ( func, ecm );
+	return 0;
+
+	unregister_netdev ( netdev );
+ err_register:
+ err_fetch_mac:
+ err_ethernet:
+ err_bulk_out:
+ err_bulk_in:
+ err_interrupt:
+ err_data:
+ err_comms:
+ err_count:
+	netdev_nullify ( netdev );
+	netdev_put ( netdev );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Remove device
+ *
+ * @v func		USB function
+ */
+static void ecm_remove ( struct usb_function *func ) {
+	struct ecm_device *ecm = usb_func_get_drvdata ( func );
+	struct net_device *netdev = ecm->netdev;
+
+	unregister_netdev ( netdev );
+	netdev_nullify ( netdev );
+	netdev_put ( netdev );
+}
+
+/** CDC-ECM device IDs */
+static struct usb_device_id ecm_ids[] = {
+	{
+		.name = "cdc-ecm",
+		.vendor = USB_ANY_ID,
+		.product = USB_ANY_ID,
+		.class = {
+			.class = USB_CLASS_CDC,
+			.subclass = USB_SUBCLASS_CDC_ECM,
+			.protocol = 0,
+		},
+	},
+};
+
+/** CDC-ECM driver */
+struct usb_driver ecm_driver __usb_driver = {
+	.ids = ecm_ids,
+	.id_count = ( sizeof ( ecm_ids ) / sizeof ( ecm_ids[0] ) ),
+	.probe = ecm_probe,
+	.remove = ecm_remove,
+};

src/drivers/net/ecm.h

@@ -12,13 +12,47 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/usb.h>
 #include <ipxe/cdc.h>
 
+/** CDC-ECM subclass */
+#define USB_SUBCLASS_CDC_ECM 0x06
+
+/** CDC-ECM interfaces */
+enum ecm_interfaces {
+	/** Communications interface */
+	ECM_INTERFACE_COMMS = 0,
+	/** Data interface */
+	ECM_INTERFACE_DATA,
+	ECM_INTERFACE_COUNT
+};
+
+/** Alternate setting for CDC-ECM data interface */
+#define ECM_DATA_ALTERNATE 1
+
+/** Set Ethernet packet filter */
+#define ECM_SET_ETHERNET_PACKET_FILTER					\
+	( USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE |		\
+	  USB_REQUEST_TYPE ( 0x43 ) )
+
+/** Ethernet packet types */
+enum ecm_ethernet_packet_filter {
+	/** Promiscuous mode */
+	ECM_PACKET_TYPE_PROMISCUOUS = 0x0001,
+	/** All multicast packets */
+	ECM_PACKET_TYPE_ALL_MULTICAST = 0x0002,
+	/** Unicast packets */
+	ECM_PACKET_TYPE_DIRECTED = 0x0004,
+	/** Broadcast packets */
+	ECM_PACKET_TYPE_BROADCAST = 0x0008,
+	/** Specified multicast packets */
+	ECM_PACKET_TYPE_MULTICAST = 0x0010,
+};
+
 /** An Ethernet Functional Descriptor */
 struct ecm_ethernet_descriptor {
 	/** Descriptor header */
 	struct usb_descriptor_header header;
 	/** Descriptor subtype */
 	uint8_t subtype;
-	/** MAC addres string */
+	/** MAC address string */
 	uint8_t mac;
 	/** Ethernet statistics bitmap */
 	uint32_t statistics;
@@ -30,6 +64,64 @@ struct ecm_ethernet_descriptor {
 	uint8_t wol;
 } __attribute__ (( packed ));
 
+/** A CDC-ECM receive ring */
+struct ecm_rx_ring {
+	/** USB endpoint */
+	struct usb_endpoint ep;
+	/** I/O buffer size */
+	size_t mtu;
+	/** Fill level */
+	unsigned int fill;
+	/** Maximum fill level */
+	unsigned int max;
+};
+
+/** A CDC-ECM transmit ring */
+struct ecm_tx_ring {
+	/** USB endpoint */
+	struct usb_endpoint ep;
+};
+
+/** A CDC-ECM network device */
+struct ecm_device {
+	/** USB device */
+	struct usb_device *usb;
+	/** USB bus */
+	struct usb_bus *bus;
+	/** Network device */
+	struct net_device *netdev;
+
+	/** Communications interface */
+	unsigned int comms;
+	/** Data interface */
+	unsigned int data;
+
+	/** Interrupt ring */
+	struct ecm_rx_ring intr;
+	/** Bulk IN ring */
+	struct ecm_rx_ring in;
+	/** Bulk OUT ring */
+	struct ecm_tx_ring out;
+};
+
+/** Interrupt maximum fill level
+ *
+ * This is a policy decision.
+ */
+#define ECM_INTR_MAX_FILL 2
+
+/** Bulk IN maximum fill level
+ *
+ * This is a policy decision.
+ */
+#define ECM_IN_MAX_FILL 8
+
+/** Bulk IN buffer size
+ *
+ * This is a policy decision.
+ */
+#define ECM_IN_MTU ( ETH_FRAME_LEN + 4 /* possible VLAN header */ )
+
 extern struct ecm_ethernet_descriptor *
 ecm_ethernet_descriptor ( struct usb_configuration_descriptor *config,
 			  struct usb_interface_descriptor *interface );