First sketch

src/include/gpxe/netdevice.h

@@ -0,0 +1,126 @@
+#ifndef _NETDEVICE_H
+#define _NETDEVICE_H
+
+/** @file
+ *
+ * Net device interface
+ *
+ */
+
+#include <stdint.h>
+#include <gpxe/llh.h>
+
+struct net_device;
+struct pk_buff;
+
+/**
+ * A network device
+ *
+ * Note that this structure must represent a generic network device,
+ * not just an Ethernet device.
+ */
+struct net_device {
+	/** Build media-specific link-layer header
+	 *
+	 * @v netdev	Network device
+	 * @v pkb	Packet buffer
+	 * @ret rc	Return status code
+	 *
+	 * This method should convert the packet buffer's generic
+	 * link-layer header (a struct gpxehdr) into a media-specific
+	 * link-layer header (e.g. a struct ethhdr).  The generic
+	 * header should be removed from the buffer (via pkb_pull())
+	 * and the media-specific header should be prepended (via
+	 * pkb_push()) in its place.
+	 *
+	 * If a link-layer header cannot be constructed (e.g. because
+	 * of a missing ARP cache entry), then this method should
+	 * replace the contents of the packet buffer with an
+	 * appropriate ARP request or equivalent, and return -ENOENT.
+	 */
+	int ( * make_media_header ) ( struct net_device *netdev,
+				      struct pk_buff *pkb );
+	/** Transmit packet
+	 *
+	 * @v netdev	Network device
+	 * @v pkb	Packet buffer
+	 * @ret rc	Return status code
+	 *
+	 * This method should cause the hardware to initiate
+	 * transmission of the packet buffer.  The buffer may be
+	 * reused immediately after the method returns, and so the
+	 * method should either wait for packet transmission to
+	 * complete, or take a copy of the buffer contents.
+	 */
+	int ( * transmit ) ( struct net_device *netdev,
+			     struct pk_buff *pkb );
+	/** Poll for received packet
+	 *
+	 * @v netdev	Network device
+	 * @v retrieve	Flag indicating whether or not to retrieve packet
+	 * @v pkb	Packet buffer to contain received packet
+	 * @ret rc	Return status code
+	 *
+	 * This method should cause the hardware to check for a
+	 * received packet.  If no packet is available, the method
+	 * should return -EAGAIN (i.e. this method is *always*
+	 * considered to be a non-blocking read).  If a packet is
+	 * available, but @c retrieve is false, the method should
+	 * return zero for success.  If a packet is available and @c
+	 * retrieve is true, the method should fill the packet buffer
+	 * and return zero for success.
+	 */
+	int ( * poll ) ( struct net_device *netdev, int retrieve,
+			 struct pk_buff *pkb );
+	/** Parse link-layer header
+	 *
+	 * @v netdev	Network device
+	 * @v pkb	Packet buffer
+	 * @ret rc	Return status code
+	 *
+	 * This method should convert the packet buffer's
+	 * media-specific link-layer header (e.g. a struct ethhdr)
+	 * into a generic link-layer header (a struct gpxehdr).  It
+	 * performs the converse function of make_media_header().
+	 *
+	 * Note that the gpxehdr::addr and gpxehdr::addrlen fields
+	 * will not be filled in by this function, since doing so
+	 * would require understanding the network-layer header.
+	 */
+	int ( * make_generic_header ) ( struct net_device *netdev,
+					struct pk_buff *pkb );
+	/** Link-layer protocol
+	 *
+	 * This is an ARPHRD_XXX constant, in network-byte order.
+	 */
+	uint16_t ll_proto;
+	/** Link-layer address length */
+	uint8_t ll_addr_len;
+	/** Link-layer address
+	 *
+	 * For Ethernet, this is the MAC address.
+	 */
+	uint8_t ll_addr[MAX_LLH_ADDR_LEN];
+	/** Driver private data */
+	void *priv;
+};
+
+extern struct net_device static_single_netdev;
+
+/* Must be a macro because priv_data[] is of variable size */
+#define alloc_netdevice( priv_size ) ( {		\
+	static char priv_data[priv_size];		\
+	static_single_netdev.priv = priv_data;	\
+	&static_single_netdev; } )
+
+extern int register_netdevice ( struct net_device *netdev );
+
+static inline void unregister_netdevice ( struct net_device *netdev __unused ){
+	/* Do nothing */
+}
+
+static inline void free_netdevice ( struct net_device *netdev __unused ) {
+	/* Do nothing */
+}
+
+#endif /* _NETDEVICE_H */