text: /*
   * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License, or any later version.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   */
  
  FILE_LICENCE ( GPL2_OR_LATER );
  
  #include <string.h>
  #include <unistd.h>
  #include <byteswap.h>
  #include <pxe.h>
  #include <realmode.h>
  #include <pic8259.h>
  #include <biosint.h>
  #include <pnpbios.h>
  #include <basemem_packet.h>
  #include <ipxe/io.h>
  #include <ipxe/iobuf.h>
  #include <ipxe/netdevice.h>
  #include <ipxe/if_ether.h>
  #include <ipxe/ethernet.h>
  #include <ipxe/profile.h>
  #include <undi.h>
  #include <undinet.h>
  
  /** @file
   *
   * UNDI network device driver
   *
   */
  
  /** An UNDI NIC */
  struct undi_nic {
  	/** Device supports IRQs */
  	int irq_supported;
  	/** Assigned IRQ number */
  	unsigned int irq;
  	/** Currently processing ISR */
  	int isr_processing;
  	/** Bug workarounds */
  	int hacks;
  };
  
  /* Disambiguate the various error causes */
  #define EINFO_EPXECALL							\
  	__einfo_uniqify ( EINFO_EPLATFORM, 0x01,			\
  			  "External PXE API error" )
  #define EPXECALL( status ) EPLATFORM ( EINFO_EPXECALL, status )
  
  /**
   * @defgroup undi_hacks UNDI workarounds
   * @{
   */
  
  /** Work around Etherboot 5.4 bugs */
  #define UNDI_HACK_EB54		0x0001
  
  /** @} */
  
  /** Maximum number of times to retry PXENV_UNDI_INITIALIZE */
  #define UNDI_INITIALIZE_RETRY_MAX 10
  
  /** Delay between retries of PXENV_UNDI_INITIALIZE */
  #define UNDI_INITIALIZE_RETRY_DELAY_MS 200
  
  /** Maximum number of received packets per poll */
  #define UNDI_RX_QUOTA 4
  
  /** Alignment of received frame payload */
  #define UNDI_RX_ALIGN 16
  
  static void undinet_close ( struct net_device *netdev );
  
  /**
   * UNDI parameter block
   *
   * Used as the parameter block for all UNDI API calls.  Resides in
   * base memory.
   */
  static union u_PXENV_ANY __bss16 ( undinet_params );
  #define undinet_params __use_data16 ( undinet_params )
  
  /**
   * UNDI entry point
   *
   * Used as the indirection vector for all UNDI API calls.  Resides in
   * base memory.
   */
  SEGOFF16_t __bss16 ( undinet_entry_point );
  #define undinet_entry_point __use_data16 ( undinet_entry_point )
  
  /** IRQ profiler */
  static struct profiler undinet_irq_profiler __profiler =
  	{ .name = "undinet.irq" };
  
  /** Receive profiler */
  static struct profiler undinet_rx_profiler __profiler =
  	{ .name = "undinet.rx" };
  
  /** A PXE API call breakdown profiler */
  struct undinet_profiler {
  	/** Total time spent performing REAL_CALL() */
  	struct profiler total;
  	/** Time spent transitioning to real mode */
  	struct profiler p2r;
  	/** Time spent in external code */
  	struct profiler ext;
  	/** Time spent transitioning back to protected mode */
  	struct profiler r2p;
  };
  
  /** PXENV_UNDI_TRANSMIT profiler */
  static struct undinet_profiler undinet_tx_profiler __profiler = {
  	{ .name = "undinet.tx" },
  	{ .name = "undinet.tx_p2r" },
  	{ .name = "undinet.tx_ext" },
  	{ .name = "undinet.tx_r2p" },
  };
  
  /** PXENV_UNDI_ISR profiler
   *
   * Note that this profiler will not see calls to
   * PXENV_UNDI_ISR_IN_START, which are handled by the UNDI ISR and do
   * not go via undinet_call().
   */
  static struct undinet_profiler undinet_isr_profiler __profiler = {
  	{ .name = "undinet.isr" },
  	{ .name = "undinet.isr_p2r" },
  	{ .name = "undinet.isr_ext" },
  	{ .name = "undinet.isr_r2p" },
  };
  
  /** PXE unknown API call profiler
   *
   * This profiler can be used to measure the overhead of a dummy PXE
   * API call.
   */
  static struct undinet_profiler undinet_unknown_profiler __profiler = {
  	{ .name = "undinet.unknown" },
  	{ .name = "undinet.unknown_p2r" },
  	{ .name = "undinet.unknown_ext" },
  	{ .name = "undinet.unknown_r2p" },
  };
  
  /** Miscellaneous PXE API call profiler */
  static struct undinet_profiler undinet_misc_profiler __profiler = {
  	{ .name = "undinet.misc" },
  	{ .name = "undinet.misc_p2r" },
  	{ .name = "undinet.misc_ext" },
  	{ .name = "undinet.misc_r2p" },
  };
  
  /*****************************************************************************
   *
   * UNDI API call
   *
   *****************************************************************************
   */
  
  /**
   * Name PXE API call
   *
   * @v function		API call number
   * @ret name		API call name
   */
  static inline __attribute__ (( always_inline )) const char *
  undinet_function_name ( unsigned int function ) {
  	switch ( function ) {
  	case PXENV_START_UNDI:
  		return "PXENV_START_UNDI";
  	case PXENV_STOP_UNDI:
  		return "PXENV_STOP_UNDI";
  	case PXENV_UNDI_STARTUP:
  		return "PXENV_UNDI_STARTUP";
  	case PXENV_UNDI_CLEANUP:
  		return "PXENV_UNDI_CLEANUP";
  	case PXENV_UNDI_INITIALIZE:
  		return "PXENV_UNDI_INITIALIZE";
  	case PXENV_UNDI_RESET_ADAPTER:
  		return "PXENV_UNDI_RESET_ADAPTER";
  	case PXENV_UNDI_SHUTDOWN:
  		return "PXENV_UNDI_SHUTDOWN";
  	case PXENV_UNDI_OPEN:
  		return "PXENV_UNDI_OPEN";
  	case PXENV_UNDI_CLOSE:
  		return "PXENV_UNDI_CLOSE";
  	case PXENV_UNDI_TRANSMIT:
  		return "PXENV_UNDI_TRANSMIT";
  	case PXENV_UNDI_SET_MCAST_ADDRESS:
  		return "PXENV_UNDI_SET_MCAST_ADDRESS";
  	case PXENV_UNDI_SET_STATION_ADDRESS:
  		return "PXENV_UNDI_SET_STATION_ADDRESS";
  	case PXENV_UNDI_SET_PACKET_FILTER:
  		return "PXENV_UNDI_SET_PACKET_FILTER";
  	case PXENV_UNDI_GET_INFORMATION:
  		return "PXENV_UNDI_GET_INFORMATION";
  	case PXENV_UNDI_GET_STATISTICS:
  		return "PXENV_UNDI_GET_STATISTICS";
  	case PXENV_UNDI_CLEAR_STATISTICS:
  		return "PXENV_UNDI_CLEAR_STATISTICS";
  	case PXENV_UNDI_INITIATE_DIAGS:
  		return "PXENV_UNDI_INITIATE_DIAGS";
  	case PXENV_UNDI_FORCE_INTERRUPT:
  		return "PXENV_UNDI_FORCE_INTERRUPT";
  	case PXENV_UNDI_GET_MCAST_ADDRESS:
  		return "PXENV_UNDI_GET_MCAST_ADDRESS";
  	case PXENV_UNDI_GET_NIC_TYPE:
  		return "PXENV_UNDI_GET_NIC_TYPE";
  	case PXENV_UNDI_GET_IFACE_INFO:
  		return "PXENV_UNDI_GET_IFACE_INFO";
  	/*
  	 * Duplicate case value; this is a bug in the PXE specification.
  	 *
  	 *	case PXENV_UNDI_GET_STATE:
  	 *		return "PXENV_UNDI_GET_STATE";
  	 */
  	case PXENV_UNDI_ISR:
  		return "PXENV_UNDI_ISR";
  	case PXENV_GET_CACHED_INFO:
  		return "PXENV_GET_CACHED_INFO";
  	default:
  		return "UNKNOWN API CALL";
  	}
  }
  
  /**
   * Determine applicable profiler pair (for debugging)
   *
   * @v function		API call number
   * @ret profiler	Profiler
   */
  static struct undinet_profiler * undinet_profiler ( unsigned int function ) {
  
  	/* Determine applicable profiler */
  	switch ( function ) {
  	case PXENV_UNDI_TRANSMIT:
  		return &undinet_tx_profiler;
  	case PXENV_UNDI_ISR:
  		return &undinet_isr_profiler;
  	case PXENV_UNKNOWN:
  		return &undinet_unknown_profiler;
  	default:
  		return &undinet_misc_profiler;
  	}
  }
  
  /**
   * Issue UNDI API call
   *
   * @v undinic		UNDI NIC
   * @v function		API call number
   * @v params		PXE parameter block
   * @v params_len	Length of PXE parameter block
   * @ret rc		Return status code
   */
  static int undinet_call ( struct undi_nic *undinic, unsigned int function,
  			  void *params, size_t params_len ) {
  	struct undinet_profiler *profiler = undinet_profiler ( function );
  	PXENV_EXIT_t exit;
  	uint32_t before;
  	uint32_t started;
  	uint32_t stopped;
  	uint32_t after;
  	int discard_D;
  	int rc;
  
  	/* Copy parameter block and entry point */
  	assert ( params_len <= sizeof ( undinet_params ) );
  	memcpy ( &undinet_params, params, params_len );
  
  	/* Call real-mode entry point.  This calling convention will
  	 * work with both the !PXE and the PXENV+ entry points.
  	 */
  	profile_start ( &profiler->total );
  	__asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t" /* gcc bug */
  					   "rdtsc\n\t"
  					   "pushl %%eax\n\t"
  					   "pushw %%es\n\t"
  					   "pushw %%di\n\t"
  					   "pushw %%bx\n\t"
  					   "lcall *undinet_entry_point\n\t"
  					   "movw %%ax, %%bx\n\t"
  					   "rdtsc\n\t"
  					   "addw $6, %%sp\n\t"
  					   "popl %%edx\n\t"
  					   "popl %%ebp\n\t" /* gcc bug */ )
  			       : "=a" ( stopped ), "=d" ( started ),
  				 "=b" ( exit ), "=D" ( discard_D )
  			       : "b" ( function ),
  			         "D" ( __from_data16 ( &undinet_params ) )
  			       : "ecx", "esi" );
  	profile_stop ( &profiler->total );
  	before = profile_started ( &profiler->total );
  	after = profile_stopped ( &profiler->total );
  	profile_start_at ( &profiler->p2r, before );
  	profile_stop_at ( &profiler->p2r, started );
  	profile_start_at ( &profiler->ext, started );
  	profile_stop_at ( &profiler->ext, stopped );
  	profile_start_at ( &profiler->r2p, stopped );
  	profile_stop_at ( &profiler->r2p, after );
  
  	/* Determine return status code based on PXENV_EXIT and
  	 * PXENV_STATUS
  	 */
  	rc = ( ( exit == PXENV_EXIT_SUCCESS ) ?
  	       0 : -EPXECALL ( undinet_params.Status ) );
  
  	/* If anything goes wrong, print as much debug information as
  	 * it's possible to give.
  	 */
  	if ( rc != 0 ) {
  		SEGOFF16_t rm_params = {
  			.segment = rm_ds,
  			.offset = __from_data16 ( &undinet_params ),
  		};
  
  		DBGC ( undinic, "UNDINIC %p %s failed: %s\n", undinic,
  		       undinet_function_name ( function ), strerror ( rc ) );
  		DBGC ( undinic, "UNDINIC %p parameters at %04x:%04x length "
  		       "%#02zx, entry point at %04x:%04x\n", undinic,
  		       rm_params.segment, rm_params.offset, params_len,
  		       undinet_entry_point.segment,
  		       undinet_entry_point.offset );
  		DBGC ( undinic, "UNDINIC %p parameters provided:\n", undinic );
  		DBGC_HDA ( undinic, rm_params, params, params_len );
  		DBGC ( undinic, "UNDINIC %p parameters returned:\n", undinic );
  		DBGC_HDA ( undinic, rm_params, &undinet_params, params_len );
  	}
  
  	/* Copy parameter block back */
  	memcpy ( params, &undinet_params, params_len );
  
  	return rc;
  }
  
  /*****************************************************************************
   *
   * UNDI interrupt service routine
   *
   *****************************************************************************
   */
  
  /**
   * UNDI interrupt service routine
   *
   * The UNDI ISR increments a counter (@c trigger_count) and exits.
   */
  extern void undiisr ( void );
  
  /** IRQ number */
  uint8_t __data16 ( undiisr_irq );
  #define undiisr_irq __use_data16 ( undiisr_irq )
  
  /** IRQ chain vector */
  struct segoff __data16 ( undiisr_next_handler );
  #define undiisr_next_handler __use_data16 ( undiisr_next_handler )
  
  /** IRQ trigger count */
  volatile uint8_t __data16 ( undiisr_trigger_count ) = 0;
  #define undiisr_trigger_count __use_data16 ( undiisr_trigger_count )
  
  /** Last observed trigger count */
  static unsigned int last_trigger_count = 0;
  
  /**
   * Hook UNDI interrupt service routine
   *
   * @v irq		IRQ number
   */
  static void undinet_hook_isr ( unsigned int irq ) {
  
  	assert ( irq <= IRQ_MAX );
  	assert ( undiisr_irq == 0 );
  
  	undiisr_irq = irq;
  	hook_bios_interrupt ( IRQ_INT ( irq ), ( ( intptr_t ) undiisr ),
  			      &undiisr_next_handler );
  }
  
  /**
   * Unhook UNDI interrupt service routine
   *
   * @v irq		IRQ number
   */
  static void undinet_unhook_isr ( unsigned int irq ) {
  
  	assert ( irq <= IRQ_MAX );
  
  	unhook_bios_interrupt ( IRQ_INT ( irq ), ( ( intptr_t ) undiisr ),
  				&undiisr_next_handler );
  	undiisr_irq = 0;
  }
  
  /**
   * Test to see if UNDI ISR has been triggered
   *
   * @ret triggered	ISR has been triggered since last check
   */
  static int undinet_isr_triggered ( void ) {
  	unsigned int this_trigger_count;
  
  	/* Read trigger_count.  Do this only once; it is volatile */
  	this_trigger_count = undiisr_trigger_count;
  
  	if ( this_trigger_count == last_trigger_count ) {
  		/* Not triggered */
  		return 0;
  	} else {
  		/* Triggered */
  		last_trigger_count = this_trigger_count;
  		return 1;
  	}
  }
  
  /*****************************************************************************
   *
   * UNDI network device interface
   *
   *****************************************************************************
   */
  
  /** UNDI transmit buffer descriptor */
  static struct s_PXENV_UNDI_TBD __data16 ( undinet_tbd );
  #define undinet_tbd __use_data16 ( undinet_tbd )
  
  /** UNDI transmit destination address */
  static uint8_t __data16_array ( undinet_destaddr, [ETH_ALEN] );
  #define undinet_destaddr __use_data16 ( undinet_destaddr )
  
  /**
   * Transmit packet
   *
   * @v netdev		Network device
   * @v iobuf		I/O buffer
   * @ret rc		Return status code
   */
  static int undinet_transmit ( struct net_device *netdev,
  			      struct io_buffer *iobuf ) {
  	struct undi_nic *undinic = netdev->priv;
  	struct s_PXENV_UNDI_TRANSMIT undi_transmit;
  	const void *ll_dest;
  	const void *ll_source;
  	uint16_t net_proto;
  	unsigned int flags;
  	uint8_t protocol;
  	size_t len;
  	int rc;
  
  	/* Technically, we ought to make sure that the previous
  	 * transmission has completed before we re-use the buffer.
  	 * However, many PXE stacks (including at least some Intel PXE
  	 * stacks and Etherboot 5.4) fail to generate TX completions.
  	 * In practice this won't be a problem, since our TX datapath
  	 * has a very low packet volume and we can get away with
  	 * assuming that a TX will be complete by the time we want to
  	 * transmit the next packet.
  	 */
  
  	/* Some PXE stacks are unable to cope with P_UNKNOWN, and will
  	 * always try to prepend a link-layer header.  Work around
  	 * these stacks by stripping the existing link-layer header
  	 * and allowing the PXE stack to (re)construct the link-layer
  	 * header itself.
  	 */
  	if ( ( rc = eth_pull ( netdev, iobuf, &ll_dest, &ll_source,
  			       &net_proto, &flags ) ) != 0 ) {
  		DBGC ( undinic, "UNDINIC %p could not strip Ethernet header: "
  		       "%s\n", undinic, strerror ( rc ) );
  		return rc;
  	}
  	memcpy ( undinet_destaddr, ll_dest, sizeof ( undinet_destaddr ) );
  	switch ( net_proto ) {
  	case htons ( ETH_P_IP ) :
  		protocol = P_IP;
  		break;
  	case htons ( ETH_P_ARP ) :
  		protocol = P_ARP;
  		break;
  	case htons ( ETH_P_RARP ) :
  		protocol = P_RARP;
  		break;
  	default:
  		/* Unknown protocol; restore the original link-layer header */
  		iob_push ( iobuf, sizeof ( struct ethhdr ) );
  		protocol = P_UNKNOWN;
  		break;
  	}
  
  	/* Copy packet to UNDI I/O buffer */
  	len = iob_len ( iobuf );
  	if ( len > sizeof ( basemem_packet ) )
  		len = sizeof ( basemem_packet );
  	memcpy ( &basemem_packet, iobuf->data, len );
  
  	/* Create PXENV_UNDI_TRANSMIT data structure */
  	memset ( &undi_transmit, 0, sizeof ( undi_transmit ) );
  	undi_transmit.Protocol = protocol;
  	undi_transmit.XmitFlag = ( ( flags & LL_BROADCAST ) ?
  				   XMT_BROADCAST : XMT_DESTADDR );
  	undi_transmit.DestAddr.segment = rm_ds;
  	undi_transmit.DestAddr.offset = __from_data16 ( &undinet_destaddr );
  	undi_transmit.TBD.segment = rm_ds;
  	undi_transmit.TBD.offset = __from_data16 ( &undinet_tbd );
  
  	/* Create PXENV_UNDI_TBD data structure */
  	undinet_tbd.ImmedLength = len;
  	undinet_tbd.Xmit.segment = rm_ds;
  	undinet_tbd.Xmit.offset = __from_data16 ( basemem_packet );
  
  	/* Issue PXE API call */
  	if ( ( rc = undinet_call ( undinic, PXENV_UNDI_TRANSMIT, &undi_transmit,
  				   sizeof ( undi_transmit ) ) ) != 0 )
  		goto done;
  
  	/* Free I/O buffer */
  	netdev_tx_complete ( netdev, iobuf );
   done:
  	return rc;
  }
  
  /** 
   * Poll for received packets
   *
   * @v netdev		Network device
   *
   * Fun, fun, fun.  UNDI drivers don't use polling; they use
   * interrupts.  We therefore cheat and pretend that an interrupt has
   * occurred every time undinet_poll() is called.  This isn't too much
   * of a hack; PCI devices share IRQs and so the first thing that a
   * proper ISR should do is call PXENV_UNDI_ISR to determine whether or
   * not the UNDI NIC generated the interrupt; there is no harm done by
   * spurious calls to PXENV_UNDI_ISR.  Similarly, we wouldn't be
   * handling them any more rapidly than the usual rate of
   * undinet_poll() being called even if we did implement a full ISR.
   * So it should work.  Ha!
   *
   * Addendum (21/10/03).  Some cards don't play nicely with this trick,
   * so instead of doing it the easy way we have to go to all the hassle
   * of installing a genuine interrupt service routine and dealing with
   * the wonderful 8259 Programmable Interrupt Controller.  Joy.
   *
   * Addendum (10/07/07).  When doing things such as iSCSI boot, in
   * which we have to co-operate with a running OS, we can't get away
   * with the "ISR-just-increments-a-counter-and-returns" trick at all,
   * because it involves tying up the PIC for far too long, and other
   * interrupt-dependent components (e.g. local disks) start breaking.
   * We therefore implement a "proper" ISR which calls PXENV_UNDI_ISR
   * from within interrupt context in order to deassert the device
   * interrupt, and sends EOI if applicable.
   */
  static void undinet_poll ( struct net_device *netdev ) {
  	struct undi_nic *undinic = netdev->priv;
  	struct s_PXENV_UNDI_ISR undi_isr;
  	struct io_buffer *iobuf = NULL;
  	unsigned int quota = UNDI_RX_QUOTA;
  	size_t len;
  	size_t reserve_len;
  	size_t frag_len;
  	size_t max_frag_len;
  	int rc;
  
  	if ( ! undinic->isr_processing ) {
  		/* Allow interrupt to occur.  Do this even if
  		 * interrupts are not known to be supported, since
  		 * some cards erroneously report that they do not
  		 * support interrupts.
  		 */
  		if ( ! undinet_isr_triggered() ) {
  			/* Allow interrupt to occur */
  			profile_start ( &undinet_irq_profiler );
  			__asm__ __volatile__ ( "sti\n\t"
  					       "nop\n\t"
  					       "nop\n\t"
  					       "cli\n\t" );
  			profile_stop ( &undinet_irq_profiler );
  
  			/* If interrupts are known to be supported,
  			 * then do nothing on this poll; wait for the
  			 * interrupt to be triggered.
  			 */
  			if ( undinic->irq_supported )
  				return;
  		}
  
  		/* Start ISR processing */
  		undinic->isr_processing = 1;
  		undi_isr.FuncFlag = PXENV_UNDI_ISR_IN_PROCESS;
  	} else {
  		/* Continue ISR processing */
  		undi_isr.FuncFlag = PXENV_UNDI_ISR_IN_GET_NEXT;
  	}
  
  	/* Run through the ISR loop */
  	while ( quota ) {
  		if ( ( rc = undinet_call ( undinic, PXENV_UNDI_ISR, &undi_isr,
  					   sizeof ( undi_isr ) ) ) != 0 ) {
  			netdev_rx_err ( netdev, NULL, rc );
  			break;
  		}
  		switch ( undi_isr.FuncFlag ) {
  		case PXENV_UNDI_ISR_OUT_TRANSMIT:
  			/* We don't care about transmit completions */
  			break;
  		case PXENV_UNDI_ISR_OUT_RECEIVE:
  			/* Packet fragment received */
  			profile_start ( &undinet_rx_profiler );
  			len = undi_isr.FrameLength;
  			frag_len = undi_isr.BufferLength;
  			reserve_len = ( -undi_isr.FrameHeaderLength &
  					( UNDI_RX_ALIGN - 1 ) );
  			if ( ( len == 0 ) || ( len < frag_len ) ) {
  				/* Don't laugh.  VMWare does it. */
  				DBGC ( undinic, "UNDINIC %p reported insane "
  				       "fragment (%zd of %zd bytes)\n",
  				       undinic, frag_len, len );
  				netdev_rx_err ( netdev, NULL, -EINVAL );
  				break;
  			}
  			if ( ! iobuf ) {
  				iobuf = alloc_iob ( reserve_len + len );
  				if ( ! iobuf ) {
  					DBGC ( undinic, "UNDINIC %p could not "
  					       "allocate %zd bytes for RX "
  					       "buffer\n", undinic, len );
  					/* Fragment will be dropped */
  					netdev_rx_err ( netdev, NULL, -ENOMEM );
  					goto done;
  				}
  				iob_reserve ( iobuf, reserve_len );
  			}
  			max_frag_len = iob_tailroom ( iobuf );
  			if ( frag_len > max_frag_len ) {
  				DBGC ( undinic, "UNDINIC %p fragment too big "
  				       "(%zd+%zd does not fit into %zd)\n",
  				       undinic, iob_len ( iobuf ), frag_len,
  				       ( iob_len ( iobuf ) + max_frag_len ) );
  				frag_len = max_frag_len;
  			}
  			copy_from_real ( iob_put ( iobuf, frag_len ),
  					 undi_isr.Frame.segment,
  					 undi_isr.Frame.offset, frag_len );
  			if ( iob_len ( iobuf ) == len ) {
  				/* Whole packet received; deliver it */
  				netdev_rx ( netdev, iob_disown ( iobuf ) );
  				quota--;
  				/* Etherboot 5.4 fails to return all packets
  				 * under mild load; pretend it retriggered.
  				 */
  				if ( undinic->hacks & UNDI_HACK_EB54 )
  					--last_trigger_count;
  			}
  			profile_stop ( &undinet_rx_profiler );
  			break;
  		case PXENV_UNDI_ISR_OUT_DONE:
  			/* Processing complete */
  			undinic->isr_processing = 0;
  			goto done;
  		default:
  			/* Should never happen.  VMWare does it routinely. */
  			DBGC ( undinic, "UNDINIC %p ISR returned invalid "
  			       "FuncFlag %04x\n", undinic, undi_isr.FuncFlag );
  			undinic->isr_processing = 0;
  			goto done;
  		}
  		undi_isr.FuncFlag = PXENV_UNDI_ISR_IN_GET_NEXT;
  	}
  
   done:
  	if ( iobuf ) {
  		DBGC ( undinic, "UNDINIC %p returned incomplete packet "
  		       "(%zd of %zd)\n", undinic, iob_len ( iobuf ),
  		       ( iob_len ( iobuf ) + iob_tailroom ( iobuf ) ) );
  		netdev_rx_err ( netdev, iobuf, -EINVAL );
  	}
  }
  
  /**
   * Open NIC
   *
   * @v netdev		Net device
   * @ret rc		Return status code
   */
  static int undinet_open ( struct net_device *netdev ) {
  	struct undi_nic *undinic = netdev->priv;
  	struct s_PXENV_UNDI_SET_STATION_ADDRESS undi_set_address;
  	struct s_PXENV_UNDI_OPEN undi_open;
  	int rc;
  
  	/* Hook interrupt service routine and enable interrupt if applicable */
  	if ( undinic->irq ) {
  		undinet_hook_isr ( undinic->irq );
  		enable_irq ( undinic->irq );
  		send_eoi ( undinic->irq );
  	}
  
  	/* Set station address.  Required for some PXE stacks; will
  	 * spuriously fail on others.  Ignore failures.  We only ever
  	 * use it to set the MAC address to the card's permanent value
  	 * anyway.
  	 */
  	memcpy ( undi_set_address.StationAddress, netdev->ll_addr,
  		 sizeof ( undi_set_address.StationAddress ) );
  	undinet_call ( undinic, PXENV_UNDI_SET_STATION_ADDRESS,
  		       &undi_set_address, sizeof ( undi_set_address ) );
  
  	/* Open NIC.  We ask for promiscuous operation, since it's the
  	 * only way to ask for all multicast addresses.  On any
  	 * switched network, it shouldn't really make a difference to
  	 * performance.
  	 */
  	memset ( &undi_open, 0, sizeof ( undi_open ) );
  	undi_open.PktFilter = ( FLTR_DIRECTED | FLTR_BRDCST | FLTR_PRMSCS );
  	if ( ( rc = undinet_call ( undinic, PXENV_UNDI_OPEN, &undi_open,
  				   sizeof ( undi_open ) ) ) != 0 )
  		goto err;
  
  	DBGC ( undinic, "UNDINIC %p opened\n", undinic );
  	return 0;
  
   err:
  	undinet_close ( netdev );
  	return rc;
  }
  
  /**
   * Close NIC
   *
   * @v netdev		Net device
   */
  static void undinet_close ( struct net_device *netdev ) {
  	struct undi_nic *undinic = netdev->priv;
  	struct s_PXENV_UNDI_ISR undi_isr;
  	struct s_PXENV_UNDI_CLOSE undi_close;
  	int rc;
  
  	/* Ensure ISR has exited cleanly */
  	while ( undinic->isr_processing ) {
  		undi_isr.FuncFlag = PXENV_UNDI_ISR_IN_GET_NEXT;
  		if ( ( rc = undinet_call ( undinic, PXENV_UNDI_ISR, &undi_isr,
  					   sizeof ( undi_isr ) ) ) != 0 )
  			break;
  		switch ( undi_isr.FuncFlag ) {
  		case PXENV_UNDI_ISR_OUT_TRANSMIT:
  		case PXENV_UNDI_ISR_OUT_RECEIVE:
  			/* Continue draining */
  			break;
  		default:
  			/* Stop processing */
  			undinic->isr_processing = 0;
  			break;
  		}
  	}
  
  	/* Close NIC */
  	undinet_call ( undinic, PXENV_UNDI_CLOSE, &undi_close,
  		       sizeof ( undi_close ) );
  
  	/* Disable interrupt and unhook ISR if applicable */
  	if ( undinic->irq ) {
  		disable_irq ( undinic->irq );
  		undinet_unhook_isr ( undinic->irq );
  	}
  
  	DBGC ( undinic, "UNDINIC %p closed\n", undinic );
  }
  
  /**
   * Enable/disable interrupts
   *
   * @v netdev		Net device
   * @v enable		Interrupts should be enabled
   */
  static void undinet_irq ( struct net_device *netdev, int enable ) {
  	struct undi_nic *undinic = netdev->priv;
  
  	/* Cannot support interrupts yet */
  	DBGC ( undinic, "UNDINIC %p cannot %s interrupts\n",
  	       undinic, ( enable ? "enable" : "disable" ) );
  }
  
  /** UNDI network device operations */
  static struct net_device_operations undinet_operations = {
  	.open		= undinet_open,
  	.close		= undinet_close,
  	.transmit	= undinet_transmit,
  	.poll		= undinet_poll,
  	.irq   		= undinet_irq,
  };
  
  /** A device with broken support for generating interrupts */
  struct undinet_irq_broken {
  	/** PCI vendor ID */
  	uint16_t pci_vendor;
  	/** PCI device ID */
  	uint16_t pci_device;
  };
  
  /**
   * List of devices with broken support for generating interrupts
   *
   * Some PXE stacks are known to claim that IRQs are supported, but
   * then never generate interrupts.  No satisfactory solution has been
   * found to this problem; the workaround is to add the PCI vendor and
   * device IDs to this list.  This is something of a hack, since it
   * will generate false positives for identical devices with a working
   * PXE stack (e.g. those that have been reflashed with iPXE), but it's
   * an improvement on the current situation.
   */
  static const struct undinet_irq_broken undinet_irq_broken_list[] = {
  	/* HP XX70x laptops */
  	{ .pci_vendor = 0x8086, .pci_device = 0x1502 },
  	{ .pci_vendor = 0x8086, .pci_device = 0x1503 },
  	/* HP 745 G3 laptop */
  	{ .pci_vendor = 0x14e4, .pci_device = 0x1687 },
  };
  
  /**
   * Check for devices with broken support for generating interrupts
   *
   * @v desc		Device description
   * @ret irq_is_broken	Interrupt support is broken; no interrupts are generated
   */
  static int undinet_irq_is_broken ( struct device_description *desc ) {
  	const struct undinet_irq_broken *broken;
  	unsigned int i;
  
  	for ( i = 0 ; i < ( sizeof ( undinet_irq_broken_list ) /
  			    sizeof ( undinet_irq_broken_list[0] ) ) ; i++ ) {
  		broken = &undinet_irq_broken_list[i];
  		if ( ( desc->bus_type == BUS_TYPE_PCI ) &&
  		     ( desc->vendor == broken->pci_vendor ) &&
  		     ( desc->device == broken->pci_device ) ) {
  			return 1;
  		}
  	}
  	return 0;
  }
  
  /**
   * Probe UNDI device
   *
   * @v undi		UNDI device
   * @v dev		Underlying generic device
   * @ret rc		Return status code
   */
  int undinet_probe ( struct undi_device *undi, struct device *dev ) {
  	struct net_device *netdev;
  	struct undi_nic *undinic;
  	struct s_PXENV_START_UNDI start_undi;
  	struct s_PXENV_UNDI_STARTUP undi_startup;
  	struct s_PXENV_UNDI_INITIALIZE undi_init;
  	struct s_PXENV_UNDI_GET_INFORMATION undi_info;
  	struct s_PXENV_UNDI_GET_IFACE_INFO undi_iface;
  	struct s_PXENV_UNDI_SHUTDOWN undi_shutdown;
  	struct s_PXENV_UNDI_CLEANUP undi_cleanup;
  	struct s_PXENV_STOP_UNDI stop_undi;
  	unsigned int retry;
  	int rc;
  
  	/* Allocate net device */
  	netdev = alloc_etherdev ( sizeof ( *undinic ) );
  	if ( ! netdev )
  		return -ENOMEM;
  	netdev_init ( netdev, &undinet_operations );
  	undinic = netdev->priv;
  	undi_set_drvdata ( undi, netdev );
  	netdev->dev = dev;
  	memset ( undinic, 0, sizeof ( *undinic ) );
  	undinet_entry_point = undi->entry;
  	DBGC ( undinic, "UNDINIC %p using UNDI %p\n", undinic, undi );
  
  	/* Hook in UNDI stack */
  	if ( ! ( undi->flags & UNDI_FL_STARTED ) ) {
  		memset ( &start_undi, 0, sizeof ( start_undi ) );
  		start_undi.AX = undi->pci_busdevfn;
  		start_undi.BX = undi->isapnp_csn;
  		start_undi.DX = undi->isapnp_read_port;
  		start_undi.ES = BIOS_SEG;
  		start_undi.DI = find_pnp_bios();
  		if ( ( rc = undinet_call ( undinic, PXENV_START_UNDI,
  					   &start_undi,
  					   sizeof ( start_undi ) ) ) != 0 )
  			goto err_start_undi;
  	}
  	undi->flags |= UNDI_FL_STARTED;
  
  	/* Bring up UNDI stack */
  	if ( ! ( undi->flags & UNDI_FL_INITIALIZED ) ) {
  		memset ( &undi_startup, 0, sizeof ( undi_startup ) );
  		if ( ( rc = undinet_call ( undinic, PXENV_UNDI_STARTUP,
  					   &undi_startup,
  					   sizeof ( undi_startup ) ) ) != 0 )
  			goto err_undi_startup;
  		/* On some PXE stacks, PXENV_UNDI_INITIALIZE may fail
  		 * due to a transient condition (e.g. media test
  		 * failing because the link has only just come out of
  		 * reset).  We may therefore need to retry this call
  		 * several times.
  		 */
  		for ( retry = 0 ; ; ) {
  			memset ( &undi_init, 0, sizeof ( undi_init ) );
  			if ( ( rc = undinet_call ( undinic,
  						   PXENV_UNDI_INITIALIZE,
  						   &undi_init,
  						   sizeof ( undi_init ) ) ) ==0)
  				break;
  			if ( ++retry > UNDI_INITIALIZE_RETRY_MAX )
  				goto err_undi_initialize;
  			DBGC ( undinic, "UNDINIC %p retrying "
  			       "PXENV_UNDI_INITIALIZE (retry %d)\n",
  			       undinic, retry );
  			/* Delay to allow link to settle if necessary */
  			mdelay ( UNDI_INITIALIZE_RETRY_DELAY_MS );
  		}
  	}
  	undi->flags |= UNDI_FL_INITIALIZED;
  
  	/* Get device information */
  	memset ( &undi_info, 0, sizeof ( undi_info ) );
  	if ( ( rc = undinet_call ( undinic, PXENV_UNDI_GET_INFORMATION,
  				   &undi_info, sizeof ( undi_info ) ) ) != 0 )
  		goto err_undi_get_information;
  	memcpy ( netdev->hw_addr, undi_info.PermNodeAddress, ETH_ALEN );
  	memcpy ( netdev->ll_addr, undi_info.CurrentNodeAddress, ETH_ALEN );
  	undinic->irq = undi_info.IntNumber;
  	if ( undinic->irq > IRQ_MAX ) {
  		DBGC ( undinic, "UNDINIC %p has invalid IRQ %d\n",
  		       undinic, undinic->irq );
  		rc = -EINVAL;
  		goto err_bad_irq;
  	}
  	DBGC ( undinic, "UNDINIC %p has MAC address %s and IRQ %d\n",
  	       undinic, eth_ntoa ( netdev->hw_addr ), undinic->irq );
  
  	/* Get interface information */
  	memset ( &undi_iface, 0, sizeof ( undi_iface ) );
  	if ( ( rc = undinet_call ( undinic, PXENV_UNDI_GET_IFACE_INFO,
  				   &undi_iface, sizeof ( undi_iface ) ) ) != 0 )
  		goto err_undi_get_iface_info;
  	DBGC ( undinic, "UNDINIC %p has type %s, speed %d, flags %08x\n",
  	       undinic, undi_iface.IfaceType, undi_iface.LinkSpeed,
  	       undi_iface.ServiceFlags );
  	if ( ( undi_iface.ServiceFlags & SUPPORTED_IRQ ) &&
  	     ( undinic->irq != 0 ) ) {
  		undinic->irq_supported = 1;
  	}
  	DBGC ( undinic, "UNDINIC %p using %s mode\n", undinic,
  	       ( undinic->irq_supported ? "interrupt" : "polling" ) );
  	if ( strncmp ( ( ( char * ) undi_iface.IfaceType ), "Etherboot",
  		       sizeof ( undi_iface.IfaceType ) ) == 0 ) {
  		DBGC ( undinic, "UNDINIC %p Etherboot 5.4 workaround enabled\n",
  		       undinic );
  		undinic->hacks |= UNDI_HACK_EB54;
  	}
  	if ( undinet_irq_is_broken ( &dev->desc ) ) {
  		DBGC ( undinic, "UNDINIC %p forcing polling mode due to "
  		       "broken interrupts\n", undinic );
  		undinic->irq_supported = 0;
  	}
  
  	/* Register network device */
  	if ( ( rc = register_netdev ( netdev ) ) != 0 )
  		goto err_register;
  
  	/* Mark as link up; we don't handle link state */
  	netdev_link_up ( netdev );
  
  	DBGC ( undinic, "UNDINIC %p added\n", undinic );
  	return 0;
  
   err_register:
   err_undi_get_iface_info:
   err_bad_irq:
   err_undi_get_information:
   err_undi_initialize:
  	/* Shut down UNDI stack */
  	memset ( &undi_shutdown, 0, sizeof ( undi_shutdown ) );
  	undinet_call ( undinic, PXENV_UNDI_SHUTDOWN, &undi_shutdown,
  		       sizeof ( undi_shutdown ) );
  	memset ( &undi_cleanup, 0, sizeof ( undi_cleanup ) );
  	undinet_call ( undinic, PXENV_UNDI_CLEANUP, &undi_cleanup,
  		       sizeof ( undi_cleanup ) );
  	undi->flags &= ~UNDI_FL_INITIALIZED;
   err_undi_startup:
  	/* Unhook UNDI stack */
  	memset ( &stop_undi, 0, sizeof ( stop_undi ) );
  	undinet_call ( undinic, PXENV_STOP_UNDI, &stop_undi,
  		       sizeof ( stop_undi ) );
  	undi->flags &= ~UNDI_FL_STARTED;
   err_start_undi:
  	netdev_nullify ( netdev );
  	netdev_put ( netdev );
  	undi_set_drvdata ( undi, NULL );
  	return rc;
  }
  
  /**
   * Remove UNDI device
   *
   * @v undi		UNDI device
   */
  void undinet_remove ( struct undi_device *undi ) {
  	struct net_device *netdev = undi_get_drvdata ( undi );
  	struct undi_nic *undinic = netdev->priv;
  	struct s_PXENV_UNDI_SHUTDOWN undi_shutdown;
  	struct s_PXENV_UNDI_CLEANUP undi_cleanup;
  	struct s_PXENV_STOP_UNDI stop_undi;
  
  	/* Unregister net device */
  	unregister_netdev ( netdev );
  
  	/* If we are preparing for an OS boot, or if we cannot exit
  	 * via the PXE stack, then shut down the PXE stack.
  	 */
  	if ( ! ( undi->flags & UNDI_FL_KEEP_ALL ) ) {
  
  		/* Shut down UNDI stack */
  		memset ( &undi_shutdown, 0, sizeof ( undi_shutdown ) );
  		undinet_call ( undinic, PXENV_UNDI_SHUTDOWN,
  			       &undi_shutdown, sizeof ( undi_shutdown ) );
  		memset ( &undi_cleanup, 0, sizeof ( undi_cleanup ) );
  		undinet_call ( undinic, PXENV_UNDI_CLEANUP,
  			       &undi_cleanup, sizeof ( undi_cleanup ) );
  		undi->flags &= ~UNDI_FL_INITIALIZED;
  
  		/* Unhook UNDI stack */
  		memset ( &stop_undi, 0, sizeof ( stop_undi ) );
  		undinet_call ( undinic, PXENV_STOP_UNDI, &stop_undi,
  			       sizeof ( stop_undi ) );
  		undi->flags &= ~UNDI_FL_STARTED;
  	}
  
  	/* Clear entry point */
  	memset ( &undinet_entry_point, 0, sizeof ( undinet_entry_point ) );
  
  	/* Free network device */
  	netdev_nullify ( netdev );
  	netdev_put ( netdev );
  
  	DBGC ( undinic, "UNDINIC %p removed\n", undinic );
  }
  