text: /**************************************************************************
  
  Copyright (c) 2001-2003, Intel Corporation
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
  
   1. Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
  
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
  
   3. Neither the name of the Intel Corporation nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE.
  
  ***************************************************************************/
  
  /* $OpenBSD: if_em.c,v 1.331 2016/04/13 10:34:32 mpi Exp $ */
  /* $FreeBSD: if_em.c,v 1.46 2004/09/29 18:28:28 mlaier Exp $ */
  
  #include <dev/pci/if_em.h>
  #include <dev/pci/if_em_soc.h>
  
  /*********************************************************************
   *  Driver version
   *********************************************************************/
  
  #define EM_DRIVER_VERSION	"6.2.9"
  
  /*********************************************************************
   *  PCI Device ID Table
   *********************************************************************/
  const struct pci_matchid em_devices[] = {
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_80003ES2LAN_CPR_DPT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_80003ES2LAN_SDS_DPT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_80003ES2LAN_CPR_SPT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_80003ES2LAN_SDS_SPT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82540EM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82540EM_LOM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82540EP },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82540EP_LOM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82540EP_LP },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541EI },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541EI_MOBILE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541ER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541ER_LOM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541GI },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541GI_LF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82541GI_MOBILE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82542 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82543GC_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82543GC_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82544EI_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82544EI_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82544GC_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82544GC_LOM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82545EM_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82545EM_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82545GM_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82545GM_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82545GM_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546EB_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546EB_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546EB_QUAD_CPR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_PCIE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_QUAD_CPR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_QUAD_CPR_K },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82546GB_2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82547EI },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82547EI_MOBILE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82547GI },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_AF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_AT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_QUAD_CPR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_QUAD_CPR_LP },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_QUAD_FBR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_SDS_DUAL },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571EB_SDS_QUAD },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82571PT_QUAD_CPR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82572EI_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82572EI_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82572EI_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82572EI },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573E },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573E_IAMT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573E_PM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573L },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573L_PL_1 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573L_PL_2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82573V_PM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82574L },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82574LA },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82575EB_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82575EB_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82575GB_QUAD_CPR },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82575GB_QP_PM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_QUAD_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_QUAD_CU_ET2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_NS },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_NS_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82576_SERDES_QUAD },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82577LC },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82577LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82578DC },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82578DM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82579LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82579V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_SGMII },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_COPPER_NF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I210_SERDES_NF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I211_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I217_LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I217_V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_LM_2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_LM_3 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_V_2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I218_V_3 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I219_LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I219_V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I219_LM2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I219_V2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_SGMII },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_COPPER_DUAL },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82580_QUAD_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_DH89XXCC_SGMII },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_DH89XXCC_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_DH89XXCC_BPLANE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_DH89XXCC_SFP },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82583V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I350_COPPER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I350_FIBER },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I350_SERDES },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I350_SGMII },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I354_BP_1GBPS },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I354_BP_2_5GBPS },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_I354_SGMII },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_82567V_3 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IFE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IFE_G },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IFE_GT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IGP_AMT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IGP_C },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IGP_M },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH8_IGP_M_AMT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_BM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IFE },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IFE_G },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IFE_GT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IGP_AMT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IGP_C },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IGP_M },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IGP_M_AMT },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH9_IGP_M_V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH10_D_BM_LF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH10_D_BM_LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH10_R_BM_LF },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH10_R_BM_LM },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_ICH10_R_BM_V },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_1 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_2 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_3 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_4 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_5 },
  	{ PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_EP80579_LAN_6 }
  };
  
  /*********************************************************************
   *  Function prototypes
   *********************************************************************/
  int  em_probe(struct device *, void *, void *);
  void em_attach(struct device *, struct device *, void *);
  void em_defer_attach(struct device*);
  int  em_detach(struct device *, int);
  int  em_activate(struct device *, int);
  int  em_intr(void *);
  void em_start(struct ifnet *);
  int  em_ioctl(struct ifnet *, u_long, caddr_t);
  void em_watchdog(struct ifnet *);
  void em_init(void *);
  void em_stop(void *, int);
  void em_media_status(struct ifnet *, struct ifmediareq *);
  int  em_media_change(struct ifnet *);
  uint64_t  em_flowstatus(struct em_softc *);
  void em_identify_hardware(struct em_softc *);
  int  em_allocate_pci_resources(struct em_softc *);
  void em_free_pci_resources(struct em_softc *);
  void em_local_timer(void *);
  int  em_hardware_init(struct em_softc *);
  void em_setup_interface(struct em_softc *);
  int  em_setup_transmit_structures(struct em_softc *);
  void em_initialize_transmit_unit(struct em_softc *);
  int  em_setup_receive_structures(struct em_softc *);
  void em_initialize_receive_unit(struct em_softc *);
  void em_enable_intr(struct em_softc *);
  void em_disable_intr(struct em_softc *);
  void em_free_transmit_structures(struct em_softc *);
  void em_free_receive_structures(struct em_softc *);
  void em_update_stats_counters(struct em_softc *);
  void em_disable_aspm(struct em_softc *);
  void em_txeof(struct em_softc *);
  int  em_allocate_receive_structures(struct em_softc *);
  int  em_allocate_transmit_structures(struct em_softc *);
  int  em_rxfill(struct em_softc *);
  int  em_rxeof(struct em_softc *);
  void em_receive_checksum(struct em_softc *, struct em_rx_desc *,
  			 struct mbuf *);
  u_int	em_transmit_checksum_setup(struct em_softc *, struct mbuf *, u_int,
  	    u_int32_t *, u_int32_t *);
  void em_iff(struct em_softc *);
  #ifdef EM_DEBUG
  void em_print_hw_stats(struct em_softc *);
  #endif
  void em_update_link_status(struct em_softc *);
  int  em_get_buf(struct em_softc *, int);
  void em_enable_hw_vlans(struct em_softc *);
  u_int em_encap(struct em_softc *, struct mbuf *);
  void em_smartspeed(struct em_softc *);
  int  em_82547_fifo_workaround(struct em_softc *, int);
  void em_82547_update_fifo_head(struct em_softc *, int);
  int  em_82547_tx_fifo_reset(struct em_softc *);
  void em_82547_move_tail(void *arg);
  void em_82547_move_tail_locked(struct em_softc *);
  int  em_dma_malloc(struct em_softc *, bus_size_t, struct em_dma_alloc *);
  void em_dma_free(struct em_softc *, struct em_dma_alloc *);
  u_int32_t em_fill_descriptors(u_int64_t address, u_int32_t length,
  			      PDESC_ARRAY desc_array);
  void em_flush_tx_ring(struct em_softc *);
  void em_flush_rx_ring(struct em_softc *);
  void em_flush_desc_rings(struct em_softc *);
  
  /*********************************************************************
   *  OpenBSD Device Interface Entry Points
   *********************************************************************/
  
  struct cfattach em_ca = {
  	sizeof(struct em_softc), em_probe, em_attach, em_detach,
  	em_activate
  };
  
  struct cfdriver em_cd = {
  	NULL, "em", DV_IFNET
  };
  
  static int em_smart_pwr_down = FALSE;
  
  /*********************************************************************
   *  Device identification routine
   *
   *  em_probe determines if the driver should be loaded on
   *  adapter based on PCI vendor/device id of the adapter.
   *
   *  return 0 on no match, positive on match
   *********************************************************************/
  
  int
  em_probe(struct device *parent, void *match, void *aux)
  {
  	INIT_DEBUGOUT("em_probe: begin");
  
  	return (pci_matchbyid((struct pci_attach_args *)aux, em_devices,
  	    nitems(em_devices)));
  }
  
  void
  em_defer_attach(struct device *self)
  {
  	struct em_softc *sc = (struct em_softc *)self;
  	struct pci_attach_args *pa = &sc->osdep.em_pa;
  	pci_chipset_tag_t	pc = pa->pa_pc;
  	void *gcu;
  
  	INIT_DEBUGOUT("em_defer_attach: begin");
  
  	if ((gcu = em_lookup_gcu(self)) == 0) {
  		printf("%s: No GCU found, defered attachment failed\n",
  		    DEVNAME(sc));
  
  		if (sc->sc_intrhand)
  			pci_intr_disestablish(pc, sc->sc_intrhand);
  		sc->sc_intrhand = 0;
  
  		em_stop(sc, 1);
  
  		em_free_pci_resources(sc);
  
  		sc->sc_rx_desc_ring = NULL;
  		em_dma_free(sc, &sc->sc_rx_dma);
  		sc->sc_tx_desc_ring = NULL;
  		em_dma_free(sc, &sc->sc_tx_dma);
  
  		return;
  	}
  	
  	sc->hw.gcu = gcu;
  	
  	em_attach_miibus(self);			
  
  	em_setup_interface(sc);			
  
  	em_setup_link(&sc->hw);			
  
  	em_update_link_status(sc);
  }
  
  /*********************************************************************
   *  Device initialization routine
   *
   *  The attach entry point is called when the driver is being loaded.
   *  This routine identifies the type of hardware, allocates all resources
   *  and initializes the hardware.
   *
   *********************************************************************/
  
  void 
  em_attach(struct device *parent, struct device *self, void *aux)
  {
  	struct pci_attach_args *pa = aux;
  	struct em_softc *sc;
  	int defer = 0;
      
  	INIT_DEBUGOUT("em_attach: begin");
  
  	sc = (struct em_softc *)self;
  	sc->sc_dmat = pa->pa_dmat;
  	sc->osdep.em_pa = *pa;
  
  	timeout_set(&sc->timer_handle, em_local_timer, sc);
  	timeout_set(&sc->tx_fifo_timer_handle, em_82547_move_tail, sc);
  
  	/* Determine hardware revision */
  	em_identify_hardware(sc);
  
  	/*
  	 * Only use MSI on the newer PCIe parts, with the exception
  	 * of 82571/82572 due to "Byte Enables 2 and 3 Are Not Set" errata
  	 */
  	if (sc->hw.mac_type <= em_82572)
  		sc->osdep.em_pa.pa_flags &= ~PCI_FLAGS_MSI_ENABLED;
  
  	/* Parameters (to be read from user) */
  	if (sc->hw.mac_type >= em_82544) {
  		sc->sc_tx_slots = EM_MAX_TXD;
  		sc->sc_rx_slots = EM_MAX_RXD;
  	} else {
  		sc->sc_tx_slots = EM_MAX_TXD_82543;
  		sc->sc_rx_slots = EM_MAX_RXD_82543;
  	}
  	sc->tx_int_delay = EM_TIDV;
  	sc->tx_abs_int_delay = EM_TADV;
  	sc->rx_int_delay = EM_RDTR;
  	sc->rx_abs_int_delay = EM_RADV;
  	sc->hw.autoneg = DO_AUTO_NEG;
  	sc->hw.wait_autoneg_complete = WAIT_FOR_AUTO_NEG_DEFAULT;
  	sc->hw.autoneg_advertised = AUTONEG_ADV_DEFAULT;
  	sc->hw.tbi_compatibility_en = TRUE;
  	sc->sc_rx_buffer_len = EM_RXBUFFER_2048;
  
  	sc->hw.phy_init_script = 1;
  	sc->hw.phy_reset_disable = FALSE;
  
  #ifndef EM_MASTER_SLAVE
  	sc->hw.master_slave = em_ms_hw_default;
  #else
  	sc->hw.master_slave = EM_MASTER_SLAVE;
  #endif
  
  	/*
  	 * This controls when hardware reports transmit completion
  	 * status.   
  	 */
  	sc->hw.report_tx_early = 1;
  
  	if (em_allocate_pci_resources(sc))
  		goto err_pci;
  
  	/* Initialize eeprom parameters */
  	em_init_eeprom_params(&sc->hw);
  
  	/*
  	 * Set the max frame size assuming standard Ethernet
  	 * sized frames.
  	 */
  	switch (sc->hw.mac_type) {
  		case em_82573:
  		{
  			uint16_t	eeprom_data = 0;
  
  			/*
  			 * 82573 only supports Jumbo frames
  			 * if ASPM is disabled.
  			 */
  			em_read_eeprom(&sc->hw, EEPROM_INIT_3GIO_3,
  			    1, &eeprom_data);
  			if (eeprom_data & EEPROM_WORD1A_ASPM_MASK) {
  				sc->hw.max_frame_size = ETHER_MAX_LEN;
  				break;
  			}
  			/* Allow Jumbo frames */
  			/* FALLTHROUGH */
  		}
  		case em_82571:
  		case em_82572:
  		case em_82574:
  		case em_82575:
  		case em_82580:
  		case em_i210:
  		case em_i350:
  		case em_ich9lan:
  		case em_ich10lan:
  		case em_pch2lan:
  		case em_pch_lpt:
  		case em_pch_spt:
  		case em_80003es2lan:
  			/* 9K Jumbo Frame size */
  			sc->hw.max_frame_size = 9234;
  			break;
  		case em_pchlan:
  			sc->hw.max_frame_size = 4096;
  			break;
  		case em_82542_rev2_0:
  		case em_82542_rev2_1:
  		case em_ich8lan:
  			/* Adapters that do not support Jumbo frames */
  			sc->hw.max_frame_size = ETHER_MAX_LEN;
  			break;
  		default:
  			sc->hw.max_frame_size =
  			    MAX_JUMBO_FRAME_SIZE;
  	}
  
  	sc->hw.min_frame_size = 
  	    ETHER_MIN_LEN + ETHER_CRC_LEN;
  
  	/* Allocate Transmit Descriptor ring */
  	if (em_dma_malloc(sc, sc->sc_tx_slots * sizeof(struct em_tx_desc),
  	    &sc->sc_tx_dma) != 0) {
  		printf("%s: Unable to allocate tx_desc memory\n", 
  		       DEVNAME(sc));
  		goto err_tx_desc;
  	}
  	sc->sc_tx_desc_ring = (struct em_tx_desc *)sc->sc_tx_dma.dma_vaddr;
  
  	/* Allocate Receive Descriptor ring */
  	if (em_dma_malloc(sc, sc->sc_rx_slots * sizeof(struct em_rx_desc),
  	    &sc->sc_rx_dma) != 0) {
  		printf("%s: Unable to allocate rx_desc memory\n",
  		       DEVNAME(sc));
  		goto err_rx_desc;
  	}
  	sc->sc_rx_desc_ring = (struct em_rx_desc *)sc->sc_rx_dma.dma_vaddr;
  
  	/* Initialize the hardware */
  	if ((defer = em_hardware_init(sc))) {
  		if (defer == EAGAIN)
  			config_defer(self, em_defer_attach);
  		else {
  			printf("%s: Unable to initialize the hardware\n",
  			    DEVNAME(sc));
  			goto err_hw_init;
  		}
  	}
  
  	if (sc->hw.mac_type == em_80003es2lan || sc->hw.mac_type == em_82575 ||
  	    sc->hw.mac_type == em_82580 || sc->hw.mac_type == em_i210 ||
  	    sc->hw.mac_type == em_i350) {
  		uint32_t reg = EM_READ_REG(&sc->hw, E1000_STATUS);
  		sc->hw.bus_func = (reg & E1000_STATUS_FUNC_MASK) >>
  		    E1000_STATUS_FUNC_SHIFT;
  
  		switch (sc->hw.bus_func) {
  		case 0:
  			sc->hw.swfw = E1000_SWFW_PHY0_SM;
  			break;
  		case 1:
  			sc->hw.swfw = E1000_SWFW_PHY1_SM;
  			break;
  		case 2:
  			sc->hw.swfw = E1000_SWFW_PHY2_SM;
  			break;
  		case 3:
  			sc->hw.swfw = E1000_SWFW_PHY3_SM;
  			break;
  		}
  	} else {
  		sc->hw.bus_func = 0;
  	}
  
  	/* Copy the permanent MAC address out of the EEPROM */
  	if (em_read_mac_addr(&sc->hw) < 0) {
  		printf("%s: EEPROM read error while reading mac address\n",
  		       DEVNAME(sc));
  		goto err_mac_addr;
  	}
  
  	bcopy(sc->hw.mac_addr, sc->sc_ac.ac_enaddr, ETHER_ADDR_LEN);
  
  	/* Setup OS specific network interface */
  	if (!defer)
  		em_setup_interface(sc);
  
  	/* Initialize statistics */
  	em_clear_hw_cntrs(&sc->hw);
  #ifndef SMALL_KERNEL
  	em_update_stats_counters(sc);
  #endif
  	sc->hw.get_link_status = 1;
  	if (!defer)
  		em_update_link_status(sc);
  
  	printf(", address %s\n", ether_sprintf(sc->sc_ac.ac_enaddr));
  
  	/* Indicate SOL/IDER usage */
  	if (em_check_phy_reset_block(&sc->hw))
  		printf("%s: PHY reset is blocked due to SOL/IDER session.\n",
  		    DEVNAME(sc));
  
  	/* Identify 82544 on PCI-X */
  	em_get_bus_info(&sc->hw);
  	if (sc->hw.bus_type == em_bus_type_pcix &&
  	    sc->hw.mac_type == em_82544)
  		sc->pcix_82544 = TRUE;
          else
  		sc->pcix_82544 = FALSE;
  
  	sc->hw.icp_xxxx_is_link_up = FALSE;
  
  	INIT_DEBUGOUT("em_attach: end");
  	return;
  
  err_mac_addr:
  err_hw_init:
  	sc->sc_rx_desc_ring = NULL;
  	em_dma_free(sc, &sc->sc_rx_dma);
  err_rx_desc:
  	sc->sc_tx_desc_ring = NULL;
  	em_dma_free(sc, &sc->sc_tx_dma);
  err_tx_desc:
  err_pci:
  	em_free_pci_resources(sc);
  }
  
  /*********************************************************************
   *  Transmit entry point
   *
   *  em_start is called by the stack to initiate a transmit.
   *  The driver will remain in this routine as long as there are
   *  packets to transmit and transmit resources are available.
   *  In case resources are not available stack is notified and
   *  the packet is requeued.
   **********************************************************************/
  
  void
  em_start(struct ifnet *ifp)
  {
  	struct em_softc *sc = ifp->if_softc;
  	u_int head, free, used;
  	struct mbuf *m;
  	int post = 0;
  
  	if (!sc->link_active) {
  		IFQ_PURGE(&ifp->if_snd);
  		return;
  	}
  
  	/* calculate free space */
  	head = sc->sc_tx_desc_head;
  	free = sc->sc_tx_desc_tail;
  	if (free <= head)
  		free += sc->sc_tx_slots;
  	free -= head;
  
  	if (sc->hw.mac_type != em_82547) {
  		bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  		    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
  	}
  
  	for (;;) {
  		/* use 2 because cksum setup can use an extra slot */
  		if (EM_MAX_SCATTER + 2 > free) {
  			ifq_set_oactive(&ifp->if_snd);
  			break;
  		}
  
  		m = ifq_dequeue(&ifp->if_snd);
  		if (m == NULL)
  			break;
  
  		used = em_encap(sc, m);
  		if (used == 0) {
  			m_freem(m);
  			continue;
  		}
  
  		KASSERT(used <= free);
  
  		free -= used;
  
  #if NBPFILTER > 0
  		/* Send a copy of the frame to the BPF listener */
  		if (ifp->if_bpf)
  			bpf_mtap_ether(ifp->if_bpf, m, BPF_DIRECTION_OUT);
  #endif
  
  		/* Set timeout in case hardware has problems transmitting */
  		ifp->if_timer = EM_TX_TIMEOUT;
  
  		if (sc->hw.mac_type == em_82547) {
  			int len = m->m_pkthdr.len;
  
  			if (sc->link_duplex == HALF_DUPLEX)
  				em_82547_move_tail_locked(sc);
  			else {
  				E1000_WRITE_REG(&sc->hw, TDT,
  				    sc->sc_tx_desc_head);
  				em_82547_update_fifo_head(sc, len);
  			}
  		}
  
  		post = 1;
  	}
  
  	if (sc->hw.mac_type != em_82547) {
  		bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  		    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
  		/* 
  		 * Advance the Transmit Descriptor Tail (Tdt),
  		 * this tells the E1000 that this frame is
  		 * available to transmit.
  		 */
  		if (post)
  			E1000_WRITE_REG(&sc->hw, TDT, sc->sc_tx_desc_head);
  	}
  }
  
  /*********************************************************************
   *  Ioctl entry point
   *
   *  em_ioctl is called when the user wants to configure the
   *  interface.
   *
   *  return 0 on success, positive on failure
   **********************************************************************/
  
  int
  em_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
  {
  	int		error = 0;
  	struct ifreq   *ifr = (struct ifreq *) data;
  	struct em_softc *sc = ifp->if_softc;
  	int s;
  
  	s = splnet();
  
  	switch (command) {
  	case SIOCSIFADDR:
  		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCSIFADDR (Set Interface "
  			       "Addr)");
  		if (!(ifp->if_flags & IFF_UP)) {
  			ifp->if_flags |= IFF_UP;
  			em_init(sc);
  		}
  		break;
  
  	case SIOCSIFFLAGS:
  		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCSIFFLAGS (Set Interface Flags)");
  		if (ifp->if_flags & IFF_UP) {
  			if (ifp->if_flags & IFF_RUNNING)
  				error = ENETRESET;
  			else
  				em_init(sc);
  		} else {
  			if (ifp->if_flags & IFF_RUNNING)
  				em_stop(sc, 0);
  		}
  		break;
  
  	case SIOCSIFMEDIA:
  		/* Check SOL/IDER usage */
  		if (em_check_phy_reset_block(&sc->hw)) {
  			printf("%s: Media change is blocked due to SOL/IDER session.\n",
  			    DEVNAME(sc));
  			break;
  		}
  	case SIOCGIFMEDIA:
  		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCxIFMEDIA (Get/Set Interface Media)");
  		error = ifmedia_ioctl(ifp, ifr, &sc->media, command);
  		break;
  
  	case SIOCGIFRXR:
  		error = if_rxr_ioctl((struct if_rxrinfo *)ifr->ifr_data,
  		    NULL, EM_MCLBYTES, &sc->sc_rx_ring);
  		break;
  
  	default:
  		error = ether_ioctl(ifp, &sc->sc_ac, command, data);
  	}
  
  	if (error == ENETRESET) {
  		if (ifp->if_flags & IFF_RUNNING) {
  			em_disable_intr(sc);
  			em_iff(sc);
  			if (sc->hw.mac_type == em_82542_rev2_0)
  				em_initialize_receive_unit(sc);
  			em_enable_intr(sc);
  		}
  		error = 0;
  	}
  
  	splx(s);
  	return (error);
  }
  
  /*********************************************************************
   *  Watchdog entry point
   *
   *  This routine is called whenever hardware quits transmitting.
   *
   **********************************************************************/
  
  void
  em_watchdog(struct ifnet *ifp)
  {
  	struct em_softc *sc = ifp->if_softc;
  
  	/* If we are in this routine because of pause frames, then
  	 * don't reset the hardware.
  	 */
  	if (E1000_READ_REG(&sc->hw, STATUS) & E1000_STATUS_TXOFF) {
  		ifp->if_timer = EM_TX_TIMEOUT;
  		return;
  	}
  	printf("%s: watchdog: head %u tail %u TDH %u TDT %u\n",
  	    DEVNAME(sc),
  	    sc->sc_tx_desc_head, sc->sc_tx_desc_tail,
  	    E1000_READ_REG(&sc->hw, TDH), E1000_READ_REG(&sc->hw, TDT));
  
  	em_init(sc);
  
  	sc->watchdog_events++;
  }
  
  /*********************************************************************
   *  Init entry point
   *
   *  This routine is used in two ways. It is used by the stack as
   *  init entry point in network interface structure. It is also used
   *  by the driver as a hw/sw initialization routine to get to a
   *  consistent state.
   *
   **********************************************************************/
  
  void
  em_init(void *arg)
  {
  	struct em_softc *sc = arg;
  	struct ifnet   *ifp = &sc->sc_ac.ac_if;
  	uint32_t	pba;
  	int s;
  
  	s = splnet();
  
  	INIT_DEBUGOUT("em_init: begin");
  
  	em_stop(sc, 0);
  
  	/*
  	 * Packet Buffer Allocation (PBA)
  	 * Writing PBA sets the receive portion of the buffer
  	 * the remainder is used for the transmit buffer.
  	 *
  	 * Devices before the 82547 had a Packet Buffer of 64K.
  	 *   Default allocation: PBA=48K for Rx, leaving 16K for Tx.
  	 * After the 82547 the buffer was reduced to 40K.
  	 *   Default allocation: PBA=30K for Rx, leaving 10K for Tx.
  	 *   Note: default does not leave enough room for Jumbo Frame >10k.
  	 */
  	switch (sc->hw.mac_type) {
  	case em_82547:
  	case em_82547_rev_2: /* 82547: Total Packet Buffer is 40K */
  		if (sc->hw.max_frame_size > EM_RXBUFFER_8192)
  			pba = E1000_PBA_22K; /* 22K for Rx, 18K for Tx */
  		else
  			pba = E1000_PBA_30K; /* 30K for Rx, 10K for Tx */
  		sc->tx_fifo_head = 0;
  		sc->tx_head_addr = pba << EM_TX_HEAD_ADDR_SHIFT;
  		sc->tx_fifo_size = (E1000_PBA_40K - pba) << EM_PBA_BYTES_SHIFT;
  		break;
  	case em_82571:
  	case em_82572: /* Total Packet Buffer on these is 48k */
  	case em_82575:
  	case em_82580:
  	case em_80003es2lan:
  	case em_i350:
  		pba = E1000_PBA_32K; /* 32K for Rx, 16K for Tx */
  		break;
  	case em_i210:
  		pba = E1000_PBA_34K;
  		break;
  	case em_82573: /* 82573: Total Packet Buffer is 32K */
  		/* Jumbo frames not supported */
  		pba = E1000_PBA_12K; /* 12K for Rx, 20K for Tx */
  		break;
  	case em_82574: /* Total Packet Buffer is 40k */
  		pba = E1000_PBA_20K; /* 20K for Rx, 20K for Tx */
  		break;
  	case em_ich8lan:
  		pba = E1000_PBA_8K;
  		break;
  	case em_ich9lan:
  	case em_ich10lan:
  		/* Boost Receive side for jumbo frames */
  		if (sc->hw.max_frame_size > EM_RXBUFFER_4096)
  			pba = E1000_PBA_14K;
  		else
  			pba = E1000_PBA_10K;
  		break;
  	case em_pchlan:
  	case em_pch2lan:
  	case em_pch_lpt:
  	case em_pch_spt:
  		pba = E1000_PBA_26K;
  		break;
  	default:
  		/* Devices before 82547 had a Packet Buffer of 64K.   */
  		if (sc->hw.max_frame_size > EM_RXBUFFER_8192)
  			pba = E1000_PBA_40K; /* 40K for Rx, 24K for Tx */
  		else
  			pba = E1000_PBA_48K; /* 48K for Rx, 16K for Tx */
  	}
  	INIT_DEBUGOUT1("em_init: pba=%dK",pba);
  	E1000_WRITE_REG(&sc->hw, PBA, pba);
  
  	/* Get the latest mac address, User can use a LAA */
  	bcopy(sc->sc_ac.ac_enaddr, sc->hw.mac_addr, ETHER_ADDR_LEN);
  
  	/* Initialize the hardware */
  	if (em_hardware_init(sc)) {
  		printf("%s: Unable to initialize the hardware\n", 
  		       DEVNAME(sc));
  		splx(s);
  		return;
  	}
  	em_update_link_status(sc);
  
  	E1000_WRITE_REG(&sc->hw, VET, ETHERTYPE_VLAN);
  	if (ifp->if_capabilities & IFCAP_VLAN_HWTAGGING)
  		em_enable_hw_vlans(sc);
  
  	/* Prepare transmit descriptors and buffers */
  	if (em_setup_transmit_structures(sc)) {
  		printf("%s: Could not setup transmit structures\n", 
  		       DEVNAME(sc));
  		em_stop(sc, 0);
  		splx(s);
  		return;
  	}
  	em_initialize_transmit_unit(sc);
  
  	/* Prepare receive descriptors and buffers */
  	if (em_setup_receive_structures(sc)) {
  		printf("%s: Could not setup receive structures\n", 
  		       DEVNAME(sc));
  		em_stop(sc, 0);
  		splx(s);
  		return;
  	}
  	em_initialize_receive_unit(sc);
  
  	/* Program promiscuous mode and multicast filters. */
  	em_iff(sc);
  
  	ifp->if_flags |= IFF_RUNNING;
  	ifq_clr_oactive(&ifp->if_snd);
  
  	timeout_add_sec(&sc->timer_handle, 1);
  	em_clear_hw_cntrs(&sc->hw);
  	em_enable_intr(sc);
  
  	/* Don't reset the phy next time init gets called */
  	sc->hw.phy_reset_disable = TRUE;
  
  	splx(s);
  }
  
  /*********************************************************************
   *
   *  Interrupt Service routine
   *
   **********************************************************************/
  int 
  em_intr(void *arg)
  {
  	struct em_softc	*sc = arg;
  	struct ifnet	*ifp = &sc->sc_ac.ac_if;
  	u_int32_t	reg_icr, test_icr;
  
  	test_icr = reg_icr = E1000_READ_REG(&sc->hw, ICR);
  	if (sc->hw.mac_type >= em_82571)
  		test_icr = (reg_icr & E1000_ICR_INT_ASSERTED);
  	if (!test_icr)
  		return (0);
  
  	if (ifp->if_flags & IFF_RUNNING) {
  		em_txeof(sc);
  
  		if (em_rxeof(sc) || ISSET(reg_icr, E1000_ICR_RXO)) {
  			if (em_rxfill(sc)) {
  				E1000_WRITE_REG(&sc->hw, RDT,
  				    sc->sc_rx_desc_head);
  			}
  		}
  	}
  
  	/* Link status change */
  	if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
  		KERNEL_LOCK();
  		sc->hw.get_link_status = 1;
  		em_check_for_link(&sc->hw);
  		em_update_link_status(sc);
  		KERNEL_UNLOCK();
  	}
  
  	return (1);
  }
  
  /*********************************************************************
   *
   *  Media Ioctl callback
   *
   *  This routine is called whenever the user queries the status of
   *  the interface using ifconfig.
   *
   **********************************************************************/
  void
  em_media_status(struct ifnet *ifp, struct ifmediareq *ifmr)
  {
  	struct em_softc *sc = ifp->if_softc;
  	uint64_t fiber_type = IFM_1000_SX;
  	u_int16_t gsr;
  
  	INIT_DEBUGOUT("em_media_status: begin");
  
  	em_check_for_link(&sc->hw);
  	em_update_link_status(sc);
  
  	ifmr->ifm_status = IFM_AVALID;
  	ifmr->ifm_active = IFM_ETHER;
  
  	if (!sc->link_active) {
  		ifmr->ifm_active |= IFM_NONE;
  		return;
  	}
  
  	ifmr->ifm_status |= IFM_ACTIVE;
  
  	if (sc->hw.media_type == em_media_type_fiber ||
  	    sc->hw.media_type == em_media_type_internal_serdes) {
  		if (sc->hw.mac_type == em_82545)
  			fiber_type = IFM_1000_LX;
  		ifmr->ifm_active |= fiber_type | IFM_FDX;
  	} else {
  		switch (sc->link_speed) {
  		case 10:
  			ifmr->ifm_active |= IFM_10_T;
  			break;
  		case 100:
  			ifmr->ifm_active |= IFM_100_TX;
  			break;
  		case 1000:
  			ifmr->ifm_active |= IFM_1000_T;
  			break;
  		}
  
  		if (sc->link_duplex == FULL_DUPLEX)
  			ifmr->ifm_active |= em_flowstatus(sc) | IFM_FDX;
  		else
  			ifmr->ifm_active |= IFM_HDX;
  
  		if (IFM_SUBTYPE(ifmr->ifm_active) == IFM_1000_T) {
  			em_read_phy_reg(&sc->hw, PHY_1000T_STATUS, &gsr);
  			if (gsr & SR_1000T_MS_CONFIG_RES)
  				ifmr->ifm_active |= IFM_ETH_MASTER;
  		}
  	}
  }
  
  /*********************************************************************
   *
   *  Media Ioctl callback
   *
   *  This routine is called when the user changes speed/duplex using
   *  media/mediopt option with ifconfig.
   *
   **********************************************************************/
  int
  em_media_change(struct ifnet *ifp)
  {
  	struct em_softc *sc = ifp->if_softc;
  	struct ifmedia	*ifm = &sc->media;
  
  	INIT_DEBUGOUT("em_media_change: begin");
  
  	if (IFM_TYPE(ifm->ifm_media) != IFM_ETHER)
  		return (EINVAL);
  
  	switch (IFM_SUBTYPE(ifm->ifm_media)) {
  	case IFM_AUTO:
  		sc->hw.autoneg = DO_AUTO_NEG;
  		sc->hw.autoneg_advertised = AUTONEG_ADV_DEFAULT;
  		break;
  	case IFM_1000_LX:
  	case IFM_1000_SX:
  	case IFM_1000_T:
  		sc->hw.autoneg = DO_AUTO_NEG;
  		sc->hw.autoneg_advertised = ADVERTISE_1000_FULL;
  		break;
  	case IFM_100_TX:
  		sc->hw.autoneg = FALSE;
  		sc->hw.autoneg_advertised = 0;
  		if ((ifm->ifm_media & IFM_GMASK) == IFM_FDX)
  			sc->hw.forced_speed_duplex = em_100_full;
  		else
  			sc->hw.forced_speed_duplex = em_100_half;
  		break;
  	case IFM_10_T:
  		sc->hw.autoneg = FALSE;
  		sc->hw.autoneg_advertised = 0;
  		if ((ifm->ifm_media & IFM_GMASK) == IFM_FDX)
  			sc->hw.forced_speed_duplex = em_10_full;
  		else
  			sc->hw.forced_speed_duplex = em_10_half;
  		break;
  	default:
  		printf("%s: Unsupported media type\n", DEVNAME(sc));
  	}
  
  	/*
  	 * As the speed/duplex settings may have changed we need to
  	 * reset the PHY.
  	 */
  	sc->hw.phy_reset_disable = FALSE;
  
  	em_init(sc);
  
  	return (0);
  }
  
  uint64_t
  em_flowstatus(struct em_softc *sc)
  {
  	u_int16_t ar, lpar;
  
  	if (sc->hw.media_type == em_media_type_fiber ||
  	    sc->hw.media_type == em_media_type_internal_serdes)
  		return (0);
  
  	em_read_phy_reg(&sc->hw, PHY_AUTONEG_ADV, &ar);
  	em_read_phy_reg(&sc->hw, PHY_LP_ABILITY, &lpar);
  
  	if ((ar & NWAY_AR_PAUSE) && (lpar & NWAY_LPAR_PAUSE))
  		return (IFM_FLOW|IFM_ETH_TXPAUSE|IFM_ETH_RXPAUSE);
  	else if (!(ar & NWAY_AR_PAUSE) && (ar & NWAY_AR_ASM_DIR) &&
  		(lpar & NWAY_LPAR_PAUSE) && (lpar & NWAY_LPAR_ASM_DIR))
  		return (IFM_FLOW|IFM_ETH_TXPAUSE);
  	else if ((ar & NWAY_AR_PAUSE) && (ar & NWAY_AR_ASM_DIR) &&
  		!(lpar & NWAY_LPAR_PAUSE) && (lpar & NWAY_LPAR_ASM_DIR))
  		return (IFM_FLOW|IFM_ETH_RXPAUSE);
  
  	return (0);
  }
  
  /*********************************************************************
   *
   *  This routine maps the mbufs to tx descriptors.
   *
   *  return 0 on success, positive on failure
   **********************************************************************/
  u_int
  em_encap(struct em_softc *sc, struct mbuf *m)
  {
  	struct em_packet *pkt;
  	struct em_tx_desc *desc;
  	bus_dmamap_t map;
  	u_int32_t txd_upper, txd_lower;
  	u_int head, last, used = 0;
  	int i, j;
  
  	/* For 82544 Workaround */
  	DESC_ARRAY		desc_array;
  	u_int32_t		array_elements;
  
  	/* get a dmamap for this packet from the next free slot */
  	head = sc->sc_tx_desc_head;
  	pkt = &sc->sc_tx_pkts_ring[head];
  	map = pkt->pkt_map;
  
  	switch (bus_dmamap_load_mbuf(sc->sc_dmat, map, m, BUS_DMA_NOWAIT)) {
  	case 0:
  		break;
  	case EFBIG:
  		if (m_defrag(m, M_DONTWAIT) == 0 &&
  		    bus_dmamap_load_mbuf(sc->sc_dmat, map, m,
  		     BUS_DMA_NOWAIT) == 0)
  			break;
  
  		/* FALLTHROUGH */
  	default:
  		sc->no_tx_dma_setup++;
  		return (0);
  	}
  
  	bus_dmamap_sync(sc->sc_dmat, map,
  	    0, map->dm_mapsize,
  	    BUS_DMASYNC_PREWRITE);
  
  	if (sc->hw.mac_type == em_82547) {
  		bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  		    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
  	}
  
  	if (sc->hw.mac_type >= em_82543 && sc->hw.mac_type != em_82575 &&
  	    sc->hw.mac_type != em_82580 && sc->hw.mac_type != em_i210 &&
  	    sc->hw.mac_type != em_i350) {
  		used += em_transmit_checksum_setup(sc, m, head,
  		    &txd_upper, &txd_lower);
  	} else {
  		txd_upper = txd_lower = 0;
  	}
  
  	head += used;
  	if (head >= sc->sc_tx_slots)
  		head -= sc->sc_tx_slots;
  
  	for (i = 0; i < map->dm_nsegs; i++) {
  		/* If sc is 82544 and on PCI-X bus */
  		if (sc->pcix_82544) {
  			/*
  			 * Check the Address and Length combination and
  			 * split the data accordingly
  			 */
  			array_elements = em_fill_descriptors(
  			    map->dm_segs[i].ds_addr, map->dm_segs[i].ds_len,
  			    &desc_array);
  			for (j = 0; j < array_elements; j++) {
  				desc = &sc->sc_tx_desc_ring[head];
  
  				desc->buffer_addr = htole64(
  					desc_array.descriptor[j].address);
  				desc->lower.data = htole32(
  					(sc->sc_txd_cmd | txd_lower |
  					 (u_int16_t)desc_array.descriptor[j].length));
  				desc->upper.data = htole32(txd_upper);
  
  				last = head;
  				if (++head == sc->sc_tx_slots)
  					head = 0;
  
  				used++;
  			}
  		} else {
  			desc = &sc->sc_tx_desc_ring[head];
  
  			desc->buffer_addr = htole64(map->dm_segs[i].ds_addr);
  			desc->lower.data = htole32(sc->sc_txd_cmd |
  			    txd_lower | map->dm_segs[i].ds_len);
  			desc->upper.data = htole32(txd_upper);
  
  			last = head;
  			if (++head == sc->sc_tx_slots)
  	        		head = 0;
  
  			used++;
  		}
  	}
  
  #if NVLAN > 0
  	/* Find out if we are in VLAN mode */
  	if (m->m_flags & M_VLANTAG) {
  		/* Set the VLAN id */
  		desc->upper.fields.special = htole16(m->m_pkthdr.ether_vtag);
  
  		/* Tell hardware to add tag */
  		desc->lower.data |= htole32(E1000_TXD_CMD_VLE);
  	}
  #endif
  
  	/* mark the packet with the mbuf and last desc slot */
  	pkt->pkt_m = m;
  	pkt->pkt_eop = last;
  
  	sc->sc_tx_desc_head = head;
  
  	/* 
  	 * Last Descriptor of Packet
  	 * needs End Of Packet (EOP)
  	 * and Report Status (RS)
  	 */
  	desc->lower.data |= htole32(E1000_TXD_CMD_EOP | E1000_TXD_CMD_RS);
  
  	if (sc->hw.mac_type == em_82547) {
  		bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  		    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
  	}
  
  	return (used);
  }
  
  /*********************************************************************
   *
   * 82547 workaround to avoid controller hang in half-duplex environment.
   * The workaround is to avoid queuing a large packet that would span
   * the internal Tx FIFO ring boundary. We need to reset the FIFO pointers
   * in this case. We do that only when FIFO is quiescent.
   *
   **********************************************************************/
  void
  em_82547_move_tail_locked(struct em_softc *sc)
  {
  	uint16_t hw_tdt;
  	uint16_t sw_tdt;
  	struct em_tx_desc *tx_desc;
  	uint16_t length = 0;
  	boolean_t eop = 0;
  
  	hw_tdt = E1000_READ_REG(&sc->hw, TDT);
  	sw_tdt = sc->sc_tx_desc_head;
  
  	while (hw_tdt != sw_tdt) {
  		tx_desc = &sc->sc_tx_desc_ring[hw_tdt];
  		length += tx_desc->lower.flags.length;
  		eop = tx_desc->lower.data & E1000_TXD_CMD_EOP;
  		if (++hw_tdt == sc->sc_tx_slots)
  			hw_tdt = 0;
  
  		if (eop) {
  			if (em_82547_fifo_workaround(sc, length)) {
  				sc->tx_fifo_wrk_cnt++;
  				timeout_add(&sc->tx_fifo_timer_handle, 1);
  				break;
  			}
  			E1000_WRITE_REG(&sc->hw, TDT, hw_tdt);
  			em_82547_update_fifo_head(sc, length);
  			length = 0;
  		}
  	}
  }
  
  void
  em_82547_move_tail(void *arg)
  {
  	struct em_softc *sc = arg;
  	int s;
  
  	s = splnet();
  	em_82547_move_tail_locked(sc);
  	splx(s);
  }
  
  int
  em_82547_fifo_workaround(struct em_softc *sc, int len)
  {
  	int fifo_space, fifo_pkt_len;
  
  	fifo_pkt_len = EM_ROUNDUP(len + EM_FIFO_HDR, EM_FIFO_HDR);
  
  	if (sc->link_duplex == HALF_DUPLEX) {
  		fifo_space = sc->tx_fifo_size - sc->tx_fifo_head;
  
  		if (fifo_pkt_len >= (EM_82547_PKT_THRESH + fifo_space)) {
  			if (em_82547_tx_fifo_reset(sc))
  				return (0);
  			else
  				return (1);
  		}
  	}
  
  	return (0);
  }
  
  void
  em_82547_update_fifo_head(struct em_softc *sc, int len)
  {
  	int fifo_pkt_len = EM_ROUNDUP(len + EM_FIFO_HDR, EM_FIFO_HDR);
  
  	/* tx_fifo_head is always 16 byte aligned */
  	sc->tx_fifo_head += fifo_pkt_len;
  	if (sc->tx_fifo_head >= sc->tx_fifo_size)
  		sc->tx_fifo_head -= sc->tx_fifo_size;
  }
  
  int
  em_82547_tx_fifo_reset(struct em_softc *sc)
  {
  	uint32_t tctl;
  
  	if ((E1000_READ_REG(&sc->hw, TDT) ==
  	     E1000_READ_REG(&sc->hw, TDH)) &&
  	    (E1000_READ_REG(&sc->hw, TDFT) ==
  	     E1000_READ_REG(&sc->hw, TDFH)) &&
  	    (E1000_READ_REG(&sc->hw, TDFTS) ==
  	     E1000_READ_REG(&sc->hw, TDFHS)) &&
  	    (E1000_READ_REG(&sc->hw, TDFPC) == 0)) {
  
  		/* Disable TX unit */
  		tctl = E1000_READ_REG(&sc->hw, TCTL);
  		E1000_WRITE_REG(&sc->hw, TCTL, tctl & ~E1000_TCTL_EN);
  
  		/* Reset FIFO pointers */
  		E1000_WRITE_REG(&sc->hw, TDFT, sc->tx_head_addr);
  		E1000_WRITE_REG(&sc->hw, TDFH, sc->tx_head_addr);
  		E1000_WRITE_REG(&sc->hw, TDFTS, sc->tx_head_addr);
  		E1000_WRITE_REG(&sc->hw, TDFHS, sc->tx_head_addr);
  
  		/* Re-enable TX unit */
  		E1000_WRITE_REG(&sc->hw, TCTL, tctl);
  		E1000_WRITE_FLUSH(&sc->hw);
  
  		sc->tx_fifo_head = 0;
  		sc->tx_fifo_reset_cnt++;
  
  		return (TRUE);
  	} else
  		return (FALSE);
  }
  
  void
  em_iff(struct em_softc *sc)
  {
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  	struct arpcom *ac = &sc->sc_ac;
  	u_int32_t reg_rctl = 0;
  	u_int8_t  mta[MAX_NUM_MULTICAST_ADDRESSES * ETH_LENGTH_OF_ADDRESS];
  	struct ether_multi *enm;
  	struct ether_multistep step;
  	int i = 0;
  
  	IOCTL_DEBUGOUT("em_iff: begin");
  
  	if (sc->hw.mac_type == em_82542_rev2_0) {
  		reg_rctl = E1000_READ_REG(&sc->hw, RCTL);
  		if (sc->hw.pci_cmd_word & CMD_MEM_WRT_INVALIDATE)
  			em_pci_clear_mwi(&sc->hw);
  		reg_rctl |= E1000_RCTL_RST;
  		E1000_WRITE_REG(&sc->hw, RCTL, reg_rctl);
  		msec_delay(5);
  	}
  
  	reg_rctl = E1000_READ_REG(&sc->hw, RCTL);
  	reg_rctl &= ~(E1000_RCTL_MPE | E1000_RCTL_UPE);
  	ifp->if_flags &= ~IFF_ALLMULTI;
  
  	if (ifp->if_flags & IFF_PROMISC || ac->ac_multirangecnt > 0 ||
  	    ac->ac_multicnt > MAX_NUM_MULTICAST_ADDRESSES) {
  		ifp->if_flags |= IFF_ALLMULTI;
  		reg_rctl |= E1000_RCTL_MPE;
  		if (ifp->if_flags & IFF_PROMISC)
  			reg_rctl |= E1000_RCTL_UPE;
  	} else {
  		ETHER_FIRST_MULTI(step, ac, enm);
  		while (enm != NULL) {
  			bcopy(enm->enm_addrlo, mta + i, ETH_LENGTH_OF_ADDRESS);
  			i += ETH_LENGTH_OF_ADDRESS;
  
  			ETHER_NEXT_MULTI(step, enm);
  		}
  
  		em_mc_addr_list_update(&sc->hw, mta, ac->ac_multicnt, 0, 1);
  	}
  
  	E1000_WRITE_REG(&sc->hw, RCTL, reg_rctl);
  
  	if (sc->hw.mac_type == em_82542_rev2_0) {
  		reg_rctl = E1000_READ_REG(&sc->hw, RCTL);
  		reg_rctl &= ~E1000_RCTL_RST;
  		E1000_WRITE_REG(&sc->hw, RCTL, reg_rctl);
  		msec_delay(5);
  		if (sc->hw.pci_cmd_word & CMD_MEM_WRT_INVALIDATE)
  			em_pci_set_mwi(&sc->hw);
  	}
  }
  
  /*********************************************************************
   *  Timer routine
   *
   *  This routine checks for link status and updates statistics.
   *
   **********************************************************************/
  
  void
  em_local_timer(void *arg)
  {
  	struct ifnet   *ifp;
  	struct em_softc *sc = arg;
  	int s;
  
  	ifp = &sc->sc_ac.ac_if;
  
  	s = splnet();
  
  #ifndef SMALL_KERNEL
  	em_update_stats_counters(sc);
  #ifdef EM_DEBUG
  	if (ifp->if_flags & IFF_DEBUG && ifp->if_flags & IFF_RUNNING)
  		em_print_hw_stats(sc);
  #endif
  #endif
  	em_smartspeed(sc);
  
  	timeout_add_sec(&sc->timer_handle, 1);
  
  	splx(s);
  }
  
  void
  em_update_link_status(struct em_softc *sc)
  {
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  
  	if (E1000_READ_REG(&sc->hw, STATUS) & E1000_STATUS_LU) {
  		if (sc->link_active == 0) {
  			em_get_speed_and_duplex(&sc->hw,
  						&sc->link_speed,
  						&sc->link_duplex);
  			/* Check if we may set SPEED_MODE bit on PCI-E */
  			if ((sc->link_speed == SPEED_1000) &&
  			    ((sc->hw.mac_type == em_82571) ||
  			    (sc->hw.mac_type == em_82572) ||
  			    (sc->hw.mac_type == em_82575) ||
  			    (sc->hw.mac_type == em_82580))) {
  				int tarc0;
  
  				tarc0 = E1000_READ_REG(&sc->hw, TARC0);
  				tarc0 |= SPEED_MODE_BIT;
  				E1000_WRITE_REG(&sc->hw, TARC0, tarc0);
  			}
  			sc->link_active = 1;
  			sc->smartspeed = 0;
  			ifp->if_baudrate = IF_Mbps(sc->link_speed);
  		}
  		if (!LINK_STATE_IS_UP(ifp->if_link_state)) {
  			if (sc->link_duplex == FULL_DUPLEX)
  				ifp->if_link_state = LINK_STATE_FULL_DUPLEX;
  			else
  				ifp->if_link_state = LINK_STATE_HALF_DUPLEX;
  			if_link_state_change(ifp);
  		}
  	} else {
  		if (sc->link_active == 1) {
  			ifp->if_baudrate = sc->link_speed = 0;
  			sc->link_duplex = 0;
  			sc->link_active = 0;
  		}
  		if (ifp->if_link_state != LINK_STATE_DOWN) {
  			ifp->if_link_state = LINK_STATE_DOWN;
  			if_link_state_change(ifp);
  		}
  	}
  }
  
  /*********************************************************************
   *
   *  This routine disables all traffic on the adapter by issuing a
   *  global reset on the MAC and deallocates TX/RX buffers. 
   *
   **********************************************************************/
  
  void
  em_stop(void *arg, int softonly)
  {
  	struct em_softc *sc = arg;
  	struct ifnet   *ifp = &sc->sc_ac.ac_if;
  
  	/* Tell the stack that the interface is no longer active */
  	ifp->if_flags &= ~IFF_RUNNING;
  
  	INIT_DEBUGOUT("em_stop: begin");
  
  	timeout_del(&sc->timer_handle);
  	timeout_del(&sc->tx_fifo_timer_handle);
  
  	if (!softonly)
  		em_disable_intr(sc);
  	if (sc->hw.mac_type == em_pch_spt)
  		em_flush_desc_rings(sc);
  	if (!softonly)
  		em_reset_hw(&sc->hw);
  
  	intr_barrier(sc->sc_intrhand);
  	ifq_barrier(&ifp->if_snd);
  
  	KASSERT((ifp->if_flags & IFF_RUNNING) == 0);
  
  	ifq_clr_oactive(&ifp->if_snd);
  	ifp->if_timer = 0;
  
  	em_free_transmit_structures(sc);
  	em_free_receive_structures(sc);
  }
  
  /*********************************************************************
   *
   *  Determine hardware revision.
   *
   **********************************************************************/
  void
  em_identify_hardware(struct em_softc *sc)
  {
  	u_int32_t reg;
  	struct pci_attach_args *pa = &sc->osdep.em_pa;
  
  	/* Make sure our PCI config space has the necessary stuff set */
  	sc->hw.pci_cmd_word = pci_conf_read(pa->pa_pc, pa->pa_tag,
  					    PCI_COMMAND_STATUS_REG);
  
  	/* Save off the information about this board */
  	sc->hw.vendor_id = PCI_VENDOR(pa->pa_id);
  	sc->hw.device_id = PCI_PRODUCT(pa->pa_id);
  
  	reg = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_CLASS_REG);
  	sc->hw.revision_id = PCI_REVISION(reg);
  
  	reg = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_SUBSYS_ID_REG);
  	sc->hw.subsystem_vendor_id = PCI_VENDOR(reg);
  	sc->hw.subsystem_id = PCI_PRODUCT(reg);
  
  	/* Identify the MAC */
  	if (em_set_mac_type(&sc->hw))
  		printf("%s: Unknown MAC Type\n", DEVNAME(sc));
  
  	if (sc->hw.mac_type == em_pchlan)
  		sc->hw.revision_id = PCI_PRODUCT(pa->pa_id) & 0x0f;
  
  	if (sc->hw.mac_type == em_82541 ||
  	    sc->hw.mac_type == em_82541_rev_2 ||
  	    sc->hw.mac_type == em_82547 ||
  	    sc->hw.mac_type == em_82547_rev_2)
  		sc->hw.phy_init_script = TRUE;
  }
  
  void
  em_legacy_irq_quirk_spt(struct em_softc *sc)
  {
  	uint32_t	reg;
  
  	/* Legacy interrupt: SPT needs a quirk. */
  	if (sc->hw.mac_type != em_pch_spt)
  		return;
  	if (sc->legacy_irq == 0)
  		return;
  
  	reg = EM_READ_REG(&sc->hw, E1000_FEXTNVM7);
  	reg |= E1000_FEXTNVM7_SIDE_CLK_UNGATE;
  	EM_WRITE_REG(&sc->hw, E1000_FEXTNVM7, reg);
  
  	reg = EM_READ_REG(&sc->hw, E1000_FEXTNVM9);
  	reg |= E1000_FEXTNVM9_IOSFSB_CLKGATE_DIS |
  	    E1000_FEXTNVM9_IOSFSB_CLKREQ_DIS;
  	EM_WRITE_REG(&sc->hw, E1000_FEXTNVM9, reg);
  }
  
  int
  em_allocate_pci_resources(struct em_softc *sc)
  {
  	int		val, rid;
  	pci_intr_handle_t	ih;
  	const char		*intrstr = NULL;
  	struct pci_attach_args *pa = &sc->osdep.em_pa;
  	pci_chipset_tag_t	pc = pa->pa_pc;
  
  	val = pci_conf_read(pa->pa_pc, pa->pa_tag, EM_MMBA);
  	if (PCI_MAPREG_TYPE(val) != PCI_MAPREG_TYPE_MEM) {
  		printf(": mmba is not mem space\n");
  		return (ENXIO);
  	}
  	if (pci_mapreg_map(pa, EM_MMBA, PCI_MAPREG_MEM_TYPE(val), 0,
  	    &sc->osdep.mem_bus_space_tag, &sc->osdep.mem_bus_space_handle,
  	    &sc->osdep.em_membase, &sc->osdep.em_memsize, 0)) {
  		printf(": cannot find mem space\n");
  		return (ENXIO);
  	}
  
  	switch (sc->hw.mac_type) {
  	case em_82544:
  	case em_82540:
  	case em_82545:
  	case em_82546:
  	case em_82541:
  	case em_82541_rev_2:
  		/* Figure out where our I/O BAR is ? */
  		for (rid = PCI_MAPREG_START; rid < PCI_MAPREG_END;) {
  			val = pci_conf_read(pa->pa_pc, pa->pa_tag, rid);
  			if (PCI_MAPREG_TYPE(val) == PCI_MAPREG_TYPE_IO) {
  				sc->io_rid = rid;
  				break;
  			}
  			rid += 4;
  			if (PCI_MAPREG_MEM_TYPE(val) ==
  			    PCI_MAPREG_MEM_TYPE_64BIT)
  				rid += 4;	/* skip high bits, too */
  		}
  
  		if (pci_mapreg_map(pa, rid, PCI_MAPREG_TYPE_IO, 0,
  		    &sc->osdep.io_bus_space_tag, &sc->osdep.io_bus_space_handle,
  		    &sc->osdep.em_iobase, &sc->osdep.em_iosize, 0)) {
  			printf(": cannot find i/o space\n");
  			return (ENXIO);
  		}
  
  		sc->hw.io_base = 0;
  		break;
  	default:
  		break;
  	}
  
  	sc->osdep.em_flashoffset = 0;
  	/* for ICH8 and family we need to find the flash memory */
  	if (sc->hw.mac_type == em_pch_spt) {
  		sc->osdep.flash_bus_space_tag = sc->osdep.mem_bus_space_tag;
  		sc->osdep.flash_bus_space_handle = sc->osdep.mem_bus_space_handle;
  		sc->osdep.em_flashbase = 0;
  		sc->osdep.em_flashsize = 0;
  		sc->osdep.em_flashoffset = 0xe000;
  	} else if (IS_ICH8(sc->hw.mac_type)) {
  		val = pci_conf_read(pa->pa_pc, pa->pa_tag, EM_FLASH);
  		if (PCI_MAPREG_TYPE(val) != PCI_MAPREG_TYPE_MEM) {
  			printf(": flash is not mem space\n");
  			return (ENXIO);
  		}
  
  		if (pci_mapreg_map(pa, EM_FLASH, PCI_MAPREG_MEM_TYPE(val), 0,
  		    &sc->osdep.flash_bus_space_tag, &sc->osdep.flash_bus_space_handle,
  		    &sc->osdep.em_flashbase, &sc->osdep.em_flashsize, 0)) {
  			printf(": cannot find mem space\n");
  			return (ENXIO);
  		}
          }
  
  	sc->legacy_irq = 0;
  	if (pci_intr_map_msi(pa, &ih)) {
  		if (pci_intr_map(pa, &ih)) {
  			printf(": couldn't map interrupt\n");
  			return (ENXIO);
  		}
  		sc->legacy_irq = 1;
  	}
  
  	sc->osdep.dev = (struct device *)sc;
  	sc->hw.back = &sc->osdep;
  
  	intrstr = pci_intr_string(pc, ih);
  	sc->sc_intrhand = pci_intr_establish(pc, ih, IPL_NET | IPL_MPSAFE,
  	    em_intr, sc, DEVNAME(sc));
  	if (sc->sc_intrhand == NULL) {
  		printf(": couldn't establish interrupt");
  		if (intrstr != NULL)
  			printf(" at %s", intrstr);
  		printf("\n");
  		return (ENXIO);
  	}
  	printf(": %s", intrstr);
  
  	/*
  	 * the ICP_xxxx device has multiple, duplicate register sets for
  	 * use when it is being used as a network processor. Disable those
  	 * registers here, as they are not necessary in this context and
  	 * can confuse the system
  	 */
  	if(sc->hw.mac_type == em_icp_xxxx) {
  		int offset;
  		pcireg_t val;
  		
  		if (!pci_get_capability(sc->osdep.em_pa.pa_pc, 
  		    sc->osdep.em_pa.pa_tag, PCI_CAP_ID_ST, &offset, &val)) {
  			return (0);
  		}
  		offset += PCI_ST_SMIA_OFFSET;
  		pci_conf_write(sc->osdep.em_pa.pa_pc, sc->osdep.em_pa.pa_tag,
  		    offset, 0x06);
  		E1000_WRITE_REG(&sc->hw, IMC1, ~0x0);
  		E1000_WRITE_REG(&sc->hw, IMC2, ~0x0);
  	}
  	return (0);
  }
  
  void
  em_free_pci_resources(struct em_softc *sc)
  {
  	struct pci_attach_args *pa = &sc->osdep.em_pa;
  	pci_chipset_tag_t	pc = pa->pa_pc;
  
  	if (sc->sc_intrhand)
  		pci_intr_disestablish(pc, sc->sc_intrhand);
  	sc->sc_intrhand = 0;
  
  	if (sc->osdep.em_flashbase)
  		bus_space_unmap(sc->osdep.flash_bus_space_tag, sc->osdep.flash_bus_space_handle,
  				sc->osdep.em_flashsize);
  	sc->osdep.em_flashbase = 0;
  
  	if (sc->osdep.em_iobase)
  		bus_space_unmap(sc->osdep.io_bus_space_tag, sc->osdep.io_bus_space_handle,
  				sc->osdep.em_iosize);
  	sc->osdep.em_iobase = 0;
  
  	if (sc->osdep.em_membase)
  		bus_space_unmap(sc->osdep.mem_bus_space_tag, sc->osdep.mem_bus_space_handle,
  				sc->osdep.em_memsize);
  	sc->osdep.em_membase = 0;
  }
  
  /*********************************************************************
   *
   *  Initialize the hardware to a configuration as specified by the
   *  em_softc structure. The controller is reset, the EEPROM is
   *  verified, the MAC address is set, then the shared initialization
   *  routines are called.
   *
   **********************************************************************/
  int
  em_hardware_init(struct em_softc *sc)
  {
  	uint32_t ret_val;
  	u_int16_t rx_buffer_size;
  
  	INIT_DEBUGOUT("em_hardware_init: begin");
  	if (sc->hw.mac_type == em_pch_spt)
  		em_flush_desc_rings(sc);
  	/* Issue a global reset */
  	em_reset_hw(&sc->hw);
  
  	/* When hardware is reset, fifo_head is also reset */
  	sc->tx_fifo_head = 0;
  
  	/* Make sure we have a good EEPROM before we read from it */
  	if (em_get_flash_presence_i210(&sc->hw) &&
  	    em_validate_eeprom_checksum(&sc->hw) < 0) {
  		/*
  		 * Some PCIe parts fail the first check due to
  		 * the link being in sleep state, call it again,
  		 * if it fails a second time its a real issue.
  		 */
  		if (em_validate_eeprom_checksum(&sc->hw) < 0) {
  			printf("%s: The EEPROM Checksum Is Not Valid\n",
  			       DEVNAME(sc));
  			return (EIO);
  		}
  	}
  
  	if (em_get_flash_presence_i210(&sc->hw) &&
  	    em_read_part_num(&sc->hw, &(sc->part_num)) < 0) {
  		printf("%s: EEPROM read error while reading part number\n",
  		       DEVNAME(sc));
  		return (EIO);
  	}
  
  	/* Set up smart power down as default off on newer adapters */
  	if (!em_smart_pwr_down &&
  	     (sc->hw.mac_type == em_82571 ||
  	      sc->hw.mac_type == em_82572 ||
  	      sc->hw.mac_type == em_82575 ||
  	      sc->hw.mac_type == em_82580 ||
  	      sc->hw.mac_type == em_i210 ||
  	      sc->hw.mac_type == em_i350 )) {
  		uint16_t phy_tmp = 0;
  
  		/* Speed up time to link by disabling smart power down */
  		em_read_phy_reg(&sc->hw, IGP02E1000_PHY_POWER_MGMT, &phy_tmp);
  		phy_tmp &= ~IGP02E1000_PM_SPD;
  		em_write_phy_reg(&sc->hw, IGP02E1000_PHY_POWER_MGMT, phy_tmp);
  	}
  
  	em_legacy_irq_quirk_spt(sc);
  
  	/*
  	 * These parameters control the automatic generation (Tx) and 
  	 * response (Rx) to Ethernet PAUSE frames.
  	 * - High water mark should allow for at least two frames to be
  	 *   received after sending an XOFF.
  	 * - Low water mark works best when it is very near the high water mark.
  	 *   This allows the receiver to restart by sending XON when it has
  	 *   drained a bit.  Here we use an arbitary value of 1500 which will
  	 *   restart after one full frame is pulled from the buffer.  There
  	 *   could be several smaller frames in the buffer and if so they will
  	 *   not trigger the XON until their total number reduces the buffer
  	 *   by 1500.
  	 * - The pause time is fairly large at 1000 x 512ns = 512 usec.
  	 */
  	rx_buffer_size = ((E1000_READ_REG(&sc->hw, PBA) & 0xffff) << 10 );
  
  	sc->hw.fc_high_water = rx_buffer_size -
  	    EM_ROUNDUP(sc->hw.max_frame_size, 1024);
  	sc->hw.fc_low_water = sc->hw.fc_high_water - 1500;
  	if (sc->hw.mac_type == em_80003es2lan)
  		sc->hw.fc_pause_time = 0xFFFF;
  	else
  		sc->hw.fc_pause_time = 1000;
  	sc->hw.fc_send_xon = TRUE;
  	sc->hw.fc = E1000_FC_FULL;
  
  	em_disable_aspm(sc);
  
  	if ((ret_val = em_init_hw(&sc->hw)) != 0) {
  		if (ret_val == E1000_DEFER_INIT) {
  			INIT_DEBUGOUT("\nHardware Initialization Deferred ");
  			return (EAGAIN);
  		}
  		printf("\n%s: Hardware Initialization Failed\n",
  		       DEVNAME(sc));
  		return (EIO);
  	}
  
  	em_check_for_link(&sc->hw);
  
  	return (0);
  }
  
  /*********************************************************************
   *
   *  Setup networking device structure and register an interface.
   *
   **********************************************************************/
  void
  em_setup_interface(struct em_softc *sc)
  {
  	struct ifnet   *ifp;
  	uint64_t fiber_type = IFM_1000_SX;
  
  	INIT_DEBUGOUT("em_setup_interface: begin");
  
  	ifp = &sc->sc_ac.ac_if;
  	strlcpy(ifp->if_xname, DEVNAME(sc), IFNAMSIZ);
  	ifp->if_softc = sc;
  	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
  	ifp->if_xflags = IFXF_MPSAFE;
  	ifp->if_ioctl = em_ioctl;
  	ifp->if_start = em_start;
  	ifp->if_watchdog = em_watchdog;
  	ifp->if_hardmtu =
  		sc->hw.max_frame_size - ETHER_HDR_LEN - ETHER_CRC_LEN;
  	IFQ_SET_MAXLEN(&ifp->if_snd, sc->sc_tx_slots - 1);
  
  	ifp->if_capabilities = IFCAP_VLAN_MTU;
  
  #if NVLAN > 0
  	if (sc->hw.mac_type != em_82575 && sc->hw.mac_type != em_82580 &&
  	    sc->hw.mac_type != em_i210 && sc->hw.mac_type != em_i350)
  		ifp->if_capabilities |= IFCAP_VLAN_HWTAGGING;
  #endif
  
  	if (sc->hw.mac_type >= em_82543 && sc->hw.mac_type != em_82575 &&
  	    sc->hw.mac_type != em_82580 && sc->hw.mac_type != em_i210 &&
  	    sc->hw.mac_type != em_i350)
  		ifp->if_capabilities |= IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4;
  
  	/* 
  	 * Specify the media types supported by this adapter and register
  	 * callbacks to update media and link information
  	 */
  	ifmedia_init(&sc->media, IFM_IMASK, em_media_change,
  		     em_media_status);
  	if (sc->hw.media_type == em_media_type_fiber ||
  	    sc->hw.media_type == em_media_type_internal_serdes) {
  		if (sc->hw.mac_type == em_82545)
  			fiber_type = IFM_1000_LX;
  		ifmedia_add(&sc->media, IFM_ETHER | fiber_type | IFM_FDX, 
  			    0, NULL);
  		ifmedia_add(&sc->media, IFM_ETHER | fiber_type, 
  			    0, NULL);
  	} else {
  		ifmedia_add(&sc->media, IFM_ETHER | IFM_10_T, 0, NULL);
  		ifmedia_add(&sc->media, IFM_ETHER | IFM_10_T | IFM_FDX, 
  			    0, NULL);
  		ifmedia_add(&sc->media, IFM_ETHER | IFM_100_TX, 
  			    0, NULL);
  		ifmedia_add(&sc->media, IFM_ETHER | IFM_100_TX | IFM_FDX, 
  			    0, NULL);
  		if (sc->hw.phy_type != em_phy_ife) {
  			ifmedia_add(&sc->media, IFM_ETHER | IFM_1000_T | IFM_FDX, 
  				    0, NULL);
  			ifmedia_add(&sc->media, IFM_ETHER | IFM_1000_T, 0, NULL);
  		}
  	}
  	ifmedia_add(&sc->media, IFM_ETHER | IFM_AUTO, 0, NULL);
  	ifmedia_set(&sc->media, IFM_ETHER | IFM_AUTO);
  
  	if_attach(ifp);
  	ether_ifattach(ifp);
  }
  
  int
  em_detach(struct device *self, int flags)
  {
  	struct em_softc *sc = (struct em_softc *)self;
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  	struct pci_attach_args *pa = &sc->osdep.em_pa;
  	pci_chipset_tag_t	pc = pa->pa_pc;
  
  	if (sc->sc_intrhand)
  		pci_intr_disestablish(pc, sc->sc_intrhand);
  	sc->sc_intrhand = 0;
  
  	em_stop(sc, 1);
  
  	em_free_pci_resources(sc);
  
  	if (sc->sc_rx_desc_ring != NULL) {
  		sc->sc_rx_desc_ring = NULL;
  		em_dma_free(sc, &sc->sc_rx_dma);
  	}
  	if (sc->sc_tx_desc_ring != NULL) {
  		sc->sc_tx_desc_ring = NULL;
  		em_dma_free(sc, &sc->sc_tx_dma);
  	}
  
  	ether_ifdetach(ifp);
  	if_detach(ifp);
  
  	return (0);
  }
  
  int
  em_activate(struct device *self, int act)
  {
  	struct em_softc *sc = (struct em_softc *)self;
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  	int rv = 0;
  
  	switch (act) {
  	case DVACT_SUSPEND:
  		if (ifp->if_flags & IFF_RUNNING)
  			em_stop(sc, 0);
  		/* We have no children atm, but we will soon */
  		rv = config_activate_children(self, act);
  		break;
  	case DVACT_RESUME:
  		if (ifp->if_flags & IFF_UP)
  			em_init(sc);
  		break;
  	default:
  		rv = config_activate_children(self, act);
  		break;
  	}
  	return (rv);
  }
  
  /*********************************************************************
   *
   *  Workaround for SmartSpeed on 82541 and 82547 controllers
   *
   **********************************************************************/	
  void
  em_smartspeed(struct em_softc *sc)
  {
  	uint16_t phy_tmp;
   
  	if (sc->link_active || (sc->hw.phy_type != em_phy_igp) || 
  	    !sc->hw.autoneg || !(sc->hw.autoneg_advertised & ADVERTISE_1000_FULL))
  		return;
  
  	if (sc->smartspeed == 0) {
  		/* If Master/Slave config fault is asserted twice,
  		 * we assume back-to-back */
  		em_read_phy_reg(&sc->hw, PHY_1000T_STATUS, &phy_tmp);
  		if (!(phy_tmp & SR_1000T_MS_CONFIG_FAULT))
  			return;
  		em_read_phy_reg(&sc->hw, PHY_1000T_STATUS, &phy_tmp);
  		if (phy_tmp & SR_1000T_MS_CONFIG_FAULT) {
  			em_read_phy_reg(&sc->hw, PHY_1000T_CTRL,
  					&phy_tmp);
  			if (phy_tmp & CR_1000T_MS_ENABLE) {
  				phy_tmp &= ~CR_1000T_MS_ENABLE;
  				em_write_phy_reg(&sc->hw,
  						    PHY_1000T_CTRL, phy_tmp);
  				sc->smartspeed++;
  				if (sc->hw.autoneg &&
  				    !em_phy_setup_autoneg(&sc->hw) &&
  				    !em_read_phy_reg(&sc->hw, PHY_CTRL,
  						       &phy_tmp)) {
  					phy_tmp |= (MII_CR_AUTO_NEG_EN |  
  						    MII_CR_RESTART_AUTO_NEG);
  					em_write_phy_reg(&sc->hw,
  							 PHY_CTRL, phy_tmp);
  				}
  			}
  		}
  		return;
  	} else if (sc->smartspeed == EM_SMARTSPEED_DOWNSHIFT) {
  		/* If still no link, perhaps using 2/3 pair cable */
  		em_read_phy_reg(&sc->hw, PHY_1000T_CTRL, &phy_tmp);
  		phy_tmp |= CR_1000T_MS_ENABLE;
  		em_write_phy_reg(&sc->hw, PHY_1000T_CTRL, phy_tmp);
  		if (sc->hw.autoneg &&
  		    !em_phy_setup_autoneg(&sc->hw) &&
  		    !em_read_phy_reg(&sc->hw, PHY_CTRL, &phy_tmp)) {
  			phy_tmp |= (MII_CR_AUTO_NEG_EN |
  				    MII_CR_RESTART_AUTO_NEG);
  			em_write_phy_reg(&sc->hw, PHY_CTRL, phy_tmp);
  		}
  	}
  	/* Restart process after EM_SMARTSPEED_MAX iterations */
  	if (sc->smartspeed++ == EM_SMARTSPEED_MAX)
  		sc->smartspeed = 0;
  }
  
  /*
   * Manage DMA'able memory.
   */
  int
  em_dma_malloc(struct em_softc *sc, bus_size_t size, struct em_dma_alloc *dma)
  {
  	int r;
  
  	r = bus_dmamap_create(sc->sc_dmat, size, 1,
  	    size, 0, BUS_DMA_WAITOK | BUS_DMA_ALLOCNOW, &dma->dma_map);
  	if (r != 0)
  		return (r);
  
  	r = bus_dmamem_alloc(sc->sc_dmat, size, PAGE_SIZE, 0, &dma->dma_seg,
  	    1, &dma->dma_nseg, BUS_DMA_WAITOK | BUS_DMA_ZERO);
  	if (r != 0)
  		goto destroy;
  
  	r = bus_dmamem_map(sc->sc_dmat, &dma->dma_seg, dma->dma_nseg, size,
  	    &dma->dma_vaddr, BUS_DMA_WAITOK);
  	if (r != 0)
  		goto free;
  
  	r = bus_dmamap_load(sc->sc_dmat, dma->dma_map, dma->dma_vaddr, size,
  	    NULL, BUS_DMA_WAITOK);
  	if (r != 0)
  		goto unmap;
  
  	dma->dma_size = size;
  	return (0);
  
  unmap:
  	bus_dmamem_unmap(sc->sc_dmat, dma->dma_vaddr, size);
  free:
  	bus_dmamem_free(sc->sc_dmat, &dma->dma_seg, dma->dma_nseg);
  destroy:
  	bus_dmamap_destroy(sc->sc_dmat, dma->dma_map);
  
  	return (r);
  }
  
  void
  em_dma_free(struct em_softc *sc, struct em_dma_alloc *dma)
  {
  	bus_dmamap_unload(sc->sc_dmat, dma->dma_map);
  	bus_dmamem_unmap(sc->sc_dmat, dma->dma_vaddr, dma->dma_size);
  	bus_dmamem_free(sc->sc_dmat, &dma->dma_seg, dma->dma_nseg);
  	bus_dmamap_destroy(sc->sc_dmat, dma->dma_map);
  }
  
  /*********************************************************************
   *
   *  Allocate memory for tx_buffer structures. The tx_buffer stores all
   *  the information needed to transmit a packet on the wire.
   *
   **********************************************************************/
  int
  em_allocate_transmit_structures(struct em_softc *sc)
  {
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  	    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
  
  	sc->sc_tx_pkts_ring = mallocarray(sc->sc_tx_slots,
  	    sizeof(*sc->sc_tx_pkts_ring), M_DEVBUF, M_NOWAIT | M_ZERO);
  	if (sc->sc_tx_pkts_ring == NULL) {
  		printf("%s: Unable to allocate tx_buffer memory\n", 
  		       DEVNAME(sc));
  		return (ENOMEM);
  	}
  
  	return (0);
  }
  
  /*********************************************************************
   *
   *  Allocate and initialize transmit structures. 
   *
   **********************************************************************/
  int
  em_setup_transmit_structures(struct em_softc *sc)
  {
  	struct em_packet *pkt;
  	int error, i;
  
  	if ((error = em_allocate_transmit_structures(sc)) != 0)
  		goto fail;
  
  	bzero((void *) sc->sc_tx_desc_ring,
  	      (sizeof(struct em_tx_desc)) * sc->sc_tx_slots);
  
  	for (i = 0; i < sc->sc_tx_slots; i++) {
  		pkt = &sc->sc_tx_pkts_ring[i];
  		error = bus_dmamap_create(sc->sc_dmat, MAX_JUMBO_FRAME_SIZE,
  		    EM_MAX_SCATTER / (sc->pcix_82544 ? 2 : 1),
  		    MAX_JUMBO_FRAME_SIZE, 0, BUS_DMA_NOWAIT, &pkt->pkt_map);
  		if (error != 0) {
  			printf("%s: Unable to create TX DMA map\n",
  			    DEVNAME(sc));
  			goto fail;
  		}
  	}
  
  	sc->sc_tx_desc_head = 0;
  	sc->sc_tx_desc_tail = 0;
  
  	/* Set checksum context */
  	sc->active_checksum_context = OFFLOAD_NONE;
  
  	return (0);
  
  fail:
  	em_free_transmit_structures(sc);
  	return (error);
  }
  
  /*********************************************************************
   *
   *  Enable transmit unit.
   *
   **********************************************************************/
  void
  em_initialize_transmit_unit(struct em_softc *sc)
  {
  	u_int32_t	reg_tctl, reg_tipg = 0;
  	u_int64_t	bus_addr;
  
  	INIT_DEBUGOUT("em_initialize_transmit_unit: begin");
  
  	/* Setup the Base and Length of the Tx Descriptor Ring */
  	bus_addr = sc->sc_tx_dma.dma_map->dm_segs[0].ds_addr;
  	E1000_WRITE_REG(&sc->hw, TDLEN, 
  			sc->sc_tx_slots *
  			sizeof(struct em_tx_desc));
  	E1000_WRITE_REG(&sc->hw, TDBAH, (u_int32_t)(bus_addr >> 32));
  	E1000_WRITE_REG(&sc->hw, TDBAL, (u_int32_t)bus_addr);
  
  	/* Setup the HW Tx Head and Tail descriptor pointers */
  	E1000_WRITE_REG(&sc->hw, TDT, 0);
  	E1000_WRITE_REG(&sc->hw, TDH, 0);
  
  	HW_DEBUGOUT2("Base = %x, Length = %x\n", 
  		     E1000_READ_REG(&sc->hw, TDBAL),
  		     E1000_READ_REG(&sc->hw, TDLEN));
  
  	/* Set the default values for the Tx Inter Packet Gap timer */
  	switch (sc->hw.mac_type) {
  	case em_82542_rev2_0:
  	case em_82542_rev2_1:
  		reg_tipg = DEFAULT_82542_TIPG_IPGT;
  		reg_tipg |= DEFAULT_82542_TIPG_IPGR1 << E1000_TIPG_IPGR1_SHIFT;
  		reg_tipg |= DEFAULT_82542_TIPG_IPGR2 << E1000_TIPG_IPGR2_SHIFT;
  		break;
  	case em_80003es2lan:
  		reg_tipg = DEFAULT_82543_TIPG_IPGR1;
  		reg_tipg |= DEFAULT_80003ES2LAN_TIPG_IPGR2 << E1000_TIPG_IPGR2_SHIFT;
  		break;
  	default:
  		if (sc->hw.media_type == em_media_type_fiber ||
  		    sc->hw.media_type == em_media_type_internal_serdes)
  			reg_tipg = DEFAULT_82543_TIPG_IPGT_FIBER;
  		else
  			reg_tipg = DEFAULT_82543_TIPG_IPGT_COPPER;
  		reg_tipg |= DEFAULT_82543_TIPG_IPGR1 << E1000_TIPG_IPGR1_SHIFT;
  		reg_tipg |= DEFAULT_82543_TIPG_IPGR2 << E1000_TIPG_IPGR2_SHIFT;
  	}
  
  
  	E1000_WRITE_REG(&sc->hw, TIPG, reg_tipg);
  	E1000_WRITE_REG(&sc->hw, TIDV, sc->tx_int_delay);
  	if (sc->hw.mac_type >= em_82540)
  		E1000_WRITE_REG(&sc->hw, TADV, sc->tx_abs_int_delay);
  
  	/* Setup Transmit Descriptor Base Settings */   
  	sc->sc_txd_cmd = E1000_TXD_CMD_IFCS;
  
  	if (sc->hw.mac_type == em_82575 || sc->hw.mac_type == em_82580 ||
  	    sc->hw.mac_type == em_i210 || sc->hw.mac_type == em_i350) {
  		/* 82575/6 need to enable the TX queue and lack the IDE bit */
  		reg_tctl = E1000_READ_REG(&sc->hw, TXDCTL);
  		reg_tctl |= E1000_TXDCTL_QUEUE_ENABLE;
  		E1000_WRITE_REG(&sc->hw, TXDCTL, reg_tctl);
  	} else if (sc->tx_int_delay > 0)
  		sc->sc_txd_cmd |= E1000_TXD_CMD_IDE;
  
  	/* Program the Transmit Control Register */
  	reg_tctl = E1000_TCTL_PSP | E1000_TCTL_EN |
  		   (E1000_COLLISION_THRESHOLD << E1000_CT_SHIFT);
  	if (sc->hw.mac_type >= em_82571)
  		reg_tctl |= E1000_TCTL_MULR;
  	if (sc->link_duplex == FULL_DUPLEX)
  		reg_tctl |= E1000_FDX_COLLISION_DISTANCE << E1000_COLD_SHIFT;
  	else
  		reg_tctl |= E1000_HDX_COLLISION_DISTANCE << E1000_COLD_SHIFT;
  	/* This write will effectively turn on the transmit unit */
  	E1000_WRITE_REG(&sc->hw, TCTL, reg_tctl);
  
  	/* SPT Si errata workaround to avoid data corruption */
  
  	if (sc->hw.mac_type == em_pch_spt) {
  		uint32_t	reg_val;
  
  		reg_val = EM_READ_REG(&sc->hw, E1000_IOSFPC);
  		reg_val |= E1000_RCTL_RDMTS_HEX;
  		EM_WRITE_REG(&sc->hw, E1000_IOSFPC, reg_val);
  
  		reg_val = E1000_READ_REG(&sc->hw, TARC0);
  		reg_val |= E1000_TARC0_CB_MULTIQ_3_REQ;
  		E1000_WRITE_REG(&sc->hw, TARC0, reg_val);
  	}
  }
  
  /*********************************************************************
   *
   *  Free all transmit related data structures.
   *
   **********************************************************************/
  void
  em_free_transmit_structures(struct em_softc *sc)
  {
  	struct em_packet *pkt;
  	int i;
  
  	INIT_DEBUGOUT("free_transmit_structures: begin");
  
  	if (sc->sc_tx_pkts_ring != NULL) {
  		for (i = 0; i < sc->sc_tx_slots; i++) {
  			pkt = &sc->sc_tx_pkts_ring[i];
  
  			if (pkt->pkt_m != NULL) {
  				bus_dmamap_sync(sc->sc_dmat, pkt->pkt_map,
  				    0, pkt->pkt_map->dm_mapsize,
  				    BUS_DMASYNC_POSTWRITE);
  				bus_dmamap_unload(sc->sc_dmat, pkt->pkt_map);
  
  				m_freem(pkt->pkt_m);
  				pkt->pkt_m = NULL;
  			}
  
  			if (pkt->pkt_map != NULL) {
  				bus_dmamap_destroy(sc->sc_dmat, pkt->pkt_map);
  				pkt->pkt_map = NULL;
  			}
  		}
  
  		free(sc->sc_tx_pkts_ring, M_DEVBUF,
  		    sc->sc_tx_slots * sizeof(*sc->sc_tx_pkts_ring));
  		sc->sc_tx_pkts_ring = NULL;
  	}
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  	    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
  }
  
  /*********************************************************************
   *
   *  The offload context needs to be set when we transfer the first
   *  packet of a particular protocol (TCP/UDP). We change the
   *  context only if the protocol type changes.
   *
   **********************************************************************/
  u_int
  em_transmit_checksum_setup(struct em_softc *sc, struct mbuf *mp, u_int head,
      u_int32_t *txd_upper, u_int32_t *txd_lower)
  {
  	struct em_context_desc *TXD;
  
  	if (mp->m_pkthdr.csum_flags & M_TCP_CSUM_OUT) {
  		*txd_upper = E1000_TXD_POPTS_TXSM << 8;
  		*txd_lower = E1000_TXD_CMD_DEXT | E1000_TXD_DTYP_D;
  		if (sc->active_checksum_context == OFFLOAD_TCP_IP)
  			return (0);
  		else
  			sc->active_checksum_context = OFFLOAD_TCP_IP;
  	} else if (mp->m_pkthdr.csum_flags & M_UDP_CSUM_OUT) {
  		*txd_upper = E1000_TXD_POPTS_TXSM << 8;
  		*txd_lower = E1000_TXD_CMD_DEXT | E1000_TXD_DTYP_D;
  		if (sc->active_checksum_context == OFFLOAD_UDP_IP)
  			return (0);
  		else
  			sc->active_checksum_context = OFFLOAD_UDP_IP;
  	} else {
  		*txd_upper = 0;
  		*txd_lower = 0;
  		return (0);
  	}
  
  	/* If we reach this point, the checksum offload context
  	 * needs to be reset.
  	 */
  	TXD = (struct em_context_desc *)&sc->sc_tx_desc_ring[head];
  
  	TXD->lower_setup.ip_fields.ipcss = ETHER_HDR_LEN;
  	TXD->lower_setup.ip_fields.ipcso = 
  	    ETHER_HDR_LEN + offsetof(struct ip, ip_sum);
  	TXD->lower_setup.ip_fields.ipcse = 
  	    htole16(ETHER_HDR_LEN + sizeof(struct ip) - 1);
  
  	TXD->upper_setup.tcp_fields.tucss = 
  	    ETHER_HDR_LEN + sizeof(struct ip);
  	TXD->upper_setup.tcp_fields.tucse = htole16(0);
  
  	if (sc->active_checksum_context == OFFLOAD_TCP_IP) {
  		TXD->upper_setup.tcp_fields.tucso = 
  		    ETHER_HDR_LEN + sizeof(struct ip) + 
  		    offsetof(struct tcphdr, th_sum);
  	} else if (sc->active_checksum_context == OFFLOAD_UDP_IP) {
  		TXD->upper_setup.tcp_fields.tucso = 
  		    ETHER_HDR_LEN + sizeof(struct ip) + 
  		    offsetof(struct udphdr, uh_sum);
  	}
  
  	TXD->tcp_seg_setup.data = htole32(0);
  	TXD->cmd_and_length = htole32(sc->sc_txd_cmd | E1000_TXD_CMD_DEXT);
  
  	return (1);
  }
  
  /**********************************************************************
   *
   *  Examine each tx_buffer in the used queue. If the hardware is done
   *  processing the packet then free associated resources. The
   *  tx_buffer is put back on the free queue. 
   *
   **********************************************************************/
  void
  em_txeof(struct em_softc *sc)
  {
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  	struct em_packet *pkt;
  	struct em_tx_desc *desc;
  	u_int head, tail;
  	u_int free = 0;
  
  	head = sc->sc_tx_desc_head;
  	tail = sc->sc_tx_desc_tail;
  
  	if (head == tail)
  		return;
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  	    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_POSTREAD);
  
  	do {
  		pkt = &sc->sc_tx_pkts_ring[tail];
  		desc = &sc->sc_tx_desc_ring[pkt->pkt_eop];
  
  		if (!ISSET(desc->upper.fields.status, E1000_TXD_STAT_DD))
  			break;
  
  		bus_dmamap_sync(sc->sc_dmat, pkt->pkt_map,
  		    0, pkt->pkt_map->dm_mapsize,
  		    BUS_DMASYNC_POSTWRITE);
  		bus_dmamap_unload(sc->sc_dmat, pkt->pkt_map);
  
  		KASSERT(pkt->pkt_m != NULL);
  
  		m_freem(pkt->pkt_m);
  		pkt->pkt_m = NULL;
  
  		tail = pkt->pkt_eop;
  
  		if (++tail == sc->sc_tx_slots)
  			tail = 0;
  
  		free++;
  	} while (tail != head);
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_tx_dma.dma_map,
  	    0, sc->sc_tx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_PREREAD);
  
  	if (free == 0)
  		return;
  
  	ifp->if_opackets += free;
  
  	sc->sc_tx_desc_tail = tail;
  
  	if (ifq_is_oactive(&ifp->if_snd))
  		ifq_restart(&ifp->if_snd);
  	else if (tail == head)
  		ifp->if_timer = 0;
  }
  
  /*********************************************************************
   *
   *  Get a buffer from system mbuf buffer pool.
   *
   **********************************************************************/
  int
  em_get_buf(struct em_softc *sc, int i)
  {
  	struct mbuf    *m;
  	struct em_packet *pkt;
  	struct em_rx_desc *desc;
  	int error;
  
  	pkt = &sc->sc_rx_pkts_ring[i];
  	desc = &sc->sc_rx_desc_ring[i];
  
  	KASSERT(pkt->pkt_m == NULL);
  
  	m = MCLGETI(NULL, M_DONTWAIT, NULL, EM_MCLBYTES);
  	if (m == NULL) {
  		sc->mbuf_cluster_failed++;
  		return (ENOBUFS);
  	}
  	m->m_len = m->m_pkthdr.len = EM_MCLBYTES;
  #ifdef __STRICT_ALIGNMENT
  	m_adj(m, ETHER_ALIGN);
  #endif
  
  	error = bus_dmamap_load_mbuf(sc->sc_dmat, pkt->pkt_map,
  	    m, BUS_DMA_NOWAIT);
  	if (error) {
  		m_freem(m);
  		return (error);
  	}
  
  	bus_dmamap_sync(sc->sc_dmat, pkt->pkt_map,
  	    0, pkt->pkt_map->dm_mapsize,
  	    BUS_DMASYNC_PREREAD);
  	pkt->pkt_m = m;
  
  	memset(desc, 0, sizeof(*desc));
  	htolem64(&desc->buffer_addr, pkt->pkt_map->dm_segs[0].ds_addr);
  
  	return (0);
  }
  
  /*********************************************************************
   *
   *  Allocate memory for rx_buffer structures. Since we use one 
   *  rx_buffer per received packet, the maximum number of rx_buffer's 
   *  that we'll need is equal to the number of receive descriptors 
   *  that we've allocated.
   *
   **********************************************************************/
  int
  em_allocate_receive_structures(struct em_softc *sc)
  {
  	struct em_packet *pkt;
  	int i;
  	int error;
  
  	sc->sc_rx_pkts_ring = mallocarray(sc->sc_rx_slots,
  	    sizeof(*sc->sc_rx_pkts_ring), M_DEVBUF, M_NOWAIT | M_ZERO);
  	if (sc->sc_rx_pkts_ring == NULL) {
  		printf("%s: Unable to allocate rx_buffer memory\n", 
  		    DEVNAME(sc));
  		return (ENOMEM);
  	}
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
  
  	for (i = 0; i < sc->sc_rx_slots; i++) {
  		pkt = &sc->sc_rx_pkts_ring[i];
  
  		error = bus_dmamap_create(sc->sc_dmat, EM_MCLBYTES, 1,
  		    EM_MCLBYTES, 0, BUS_DMA_NOWAIT, &pkt->pkt_map);
  		if (error != 0) {
  			printf("%s: em_allocate_receive_structures: "
  			    "bus_dmamap_create failed; error %u\n",
  			    DEVNAME(sc), error);
  			goto fail;
  		}
  
  		pkt->pkt_m = NULL;
  	}
  
          return (0);
  
  fail:
  	em_free_receive_structures(sc);
  	return (error);
  }
  
  /*********************************************************************
   *
   *  Allocate and initialize receive structures.
   *  
   **********************************************************************/
  int
  em_setup_receive_structures(struct em_softc *sc)
  {
  	struct ifnet *ifp = &sc->sc_ac.ac_if;
  	u_int lwm;
  
  	memset(sc->sc_rx_desc_ring, 0,
  	    sc->sc_rx_slots * sizeof(*sc->sc_rx_desc_ring));
  
  	if (em_allocate_receive_structures(sc))
  		return (ENOMEM);
  
  	/* Setup our descriptor pointers */
  	sc->sc_rx_desc_tail = 0;
  	sc->sc_rx_desc_head = sc->sc_rx_slots - 1;
  
  	lwm = max(4, 2 * ((ifp->if_hardmtu / MCLBYTES) + 1));
  	if_rxr_init(&sc->sc_rx_ring, lwm, sc->sc_rx_slots);
  
  	if (em_rxfill(sc) == 0) {
  		printf("%s: unable to fill any rx descriptors\n",
  		    DEVNAME(sc));
  	}
  
  	return (0);
  }
  
  /*********************************************************************
   *
   *  Enable receive unit.
   *  
   **********************************************************************/
  void
  em_initialize_receive_unit(struct em_softc *sc)
  {
  	u_int32_t	reg_rctl;
  	u_int32_t	reg_rxcsum;
  	u_int64_t	bus_addr;
  
  	INIT_DEBUGOUT("em_initialize_receive_unit: begin");
  
  	/* Make sure receives are disabled while setting up the descriptor ring */
  	E1000_WRITE_REG(&sc->hw, RCTL, 0);
  
  	/* Set the Receive Delay Timer Register */
  	E1000_WRITE_REG(&sc->hw, RDTR, 
  			sc->rx_int_delay | E1000_RDT_FPDB);
  
  	if (sc->hw.mac_type >= em_82540) {
  		if (sc->rx_int_delay)
  			E1000_WRITE_REG(&sc->hw, RADV, sc->rx_abs_int_delay);
  
  		/* Set the interrupt throttling rate.  Value is calculated
  		 * as DEFAULT_ITR = 1/(MAX_INTS_PER_SEC * 256ns) */
  		E1000_WRITE_REG(&sc->hw, ITR, DEFAULT_ITR);
  	}
  
  	/* Setup the Base and Length of the Rx Descriptor Ring */
  	bus_addr = sc->sc_rx_dma.dma_map->dm_segs[0].ds_addr;
  	E1000_WRITE_REG(&sc->hw, RDLEN,
  	    sc->sc_rx_slots * sizeof(*sc->sc_rx_desc_ring));
  	E1000_WRITE_REG(&sc->hw, RDBAH, (u_int32_t)(bus_addr >> 32));
  	E1000_WRITE_REG(&sc->hw, RDBAL, (u_int32_t)bus_addr);
  
  	/* Setup the Receive Control Register */
  	reg_rctl = E1000_RCTL_EN | E1000_RCTL_BAM | E1000_RCTL_LBM_NO |
  	    E1000_RCTL_RDMTS_HALF |
  	    (sc->hw.mc_filter_type << E1000_RCTL_MO_SHIFT);
  
  	if (sc->hw.tbi_compatibility_on == TRUE)
  		reg_rctl |= E1000_RCTL_SBP;
  
  	/*
  	 * The i350 has a bug where it always strips the CRC whether
  	 * asked to or not.  So ask for stripped CRC here and
  	 * cope in rxeof
  	 */
  	if (sc->hw.mac_type == em_i210 || sc->hw.mac_type == em_i350)
  		reg_rctl |= E1000_RCTL_SECRC;
  
  	switch (sc->sc_rx_buffer_len) {
  	default:
  	case EM_RXBUFFER_2048:
  		reg_rctl |= E1000_RCTL_SZ_2048;
  		break;
  	case EM_RXBUFFER_4096:
  		reg_rctl |= E1000_RCTL_SZ_4096|E1000_RCTL_BSEX|E1000_RCTL_LPE;
  		break;		  
  	case EM_RXBUFFER_8192:
  		reg_rctl |= E1000_RCTL_SZ_8192|E1000_RCTL_BSEX|E1000_RCTL_LPE;
  		break;
  	case EM_RXBUFFER_16384:
  		reg_rctl |= E1000_RCTL_SZ_16384|E1000_RCTL_BSEX|E1000_RCTL_LPE;
  		break;
  	}
  
  	if (sc->hw.max_frame_size != ETHER_MAX_LEN)
  		reg_rctl |= E1000_RCTL_LPE;
  
  	/* Enable 82543 Receive Checksum Offload for TCP and UDP */
  	if (sc->hw.mac_type >= em_82543) {
  		reg_rxcsum = E1000_READ_REG(&sc->hw, RXCSUM);
  		reg_rxcsum |= (E1000_RXCSUM_IPOFL | E1000_RXCSUM_TUOFL);
  		E1000_WRITE_REG(&sc->hw, RXCSUM, reg_rxcsum);
  	}
  
  	/*
  	 * XXX TEMPORARY WORKAROUND: on some systems with 82573
  	 * long latencies are observed, like Lenovo X60.
  	 */
  	if (sc->hw.mac_type == em_82573)
  		E1000_WRITE_REG(&sc->hw, RDTR, 0x20);
  
  	if (sc->hw.mac_type == em_82575 || sc->hw.mac_type == em_82580 ||
  	    sc->hw.mac_type == em_i210 || sc->hw.mac_type == em_i350) {
  		/* 82575/6 need to enable the RX queue */
  		uint32_t reg;
  		reg = E1000_READ_REG(&sc->hw, RXDCTL);
  		reg |= E1000_RXDCTL_QUEUE_ENABLE;
  		E1000_WRITE_REG(&sc->hw, RXDCTL, reg);
  	}
  
  	/* Enable Receives */
  	E1000_WRITE_REG(&sc->hw, RCTL, reg_rctl);
  
  	/* Setup the HW Rx Head and Tail Descriptor Pointers */
  	E1000_WRITE_REG(&sc->hw, RDH, 0);
  	E1000_WRITE_REG(&sc->hw, RDT, sc->sc_rx_desc_head);
  }
  
  /*********************************************************************
   *
   *  Free receive related data structures.
   *
   **********************************************************************/
  void
  em_free_receive_structures(struct em_softc *sc)
  {
  	struct em_packet *pkt;
  	int i;
  
  	INIT_DEBUGOUT("free_receive_structures: begin");
  
  	if_rxr_init(&sc->sc_rx_ring, 0, 0);
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
  
  	if (sc->sc_rx_pkts_ring != NULL) {
  		for (i = 0; i < sc->sc_rx_slots; i++) {
  			pkt = &sc->sc_rx_pkts_ring[i];
  			if (pkt->pkt_m != NULL) {
  				bus_dmamap_sync(sc->sc_dmat, pkt->pkt_map,
  				    0, pkt->pkt_map->dm_mapsize,
  				    BUS_DMASYNC_POSTREAD);
  				bus_dmamap_unload(sc->sc_dmat, pkt->pkt_map);
  				m_freem(pkt->pkt_m);
  				pkt->pkt_m = NULL;
  			}
  			bus_dmamap_destroy(sc->sc_dmat, pkt->pkt_map);
  		}
  
  		free(sc->sc_rx_pkts_ring, M_DEVBUF,
  		    sc->sc_rx_slots * sizeof(*sc->sc_rx_pkts_ring));
  		sc->sc_rx_pkts_ring = NULL;
  	}
  
  	if (sc->fmp != NULL) {
  		m_freem(sc->fmp);
  		sc->fmp = NULL;
  		sc->lmp = NULL;
  	}
  }
  
  int
  em_rxfill(struct em_softc *sc)
  {
  	u_int slots;
  	int post = 0;
  	int i;
  
  	i = sc->sc_rx_desc_head;
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_POSTWRITE);
  
  	for (slots = if_rxr_get(&sc->sc_rx_ring, sc->sc_rx_slots);
  	    slots > 0; slots--) {
  		if (++i == sc->sc_rx_slots)
  			i = 0;
  
  		if (em_get_buf(sc, i) != 0)
  			break;
  
  		sc->sc_rx_desc_head = i;
  		post = 1;
  	}
  
  	if_rxr_put(&sc->sc_rx_ring, slots);
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_PREWRITE);
  
  	return (post);
  }
  
  /*********************************************************************
   *
   *  This routine executes in interrupt context. It replenishes
   *  the mbufs in the descriptor and sends data which has been
   *  dma'ed into host memory to upper layer.
   *
   *********************************************************************/
  int
  em_rxeof(struct em_softc *sc)
  {
  	struct ifnet	    *ifp = &sc->sc_ac.ac_if;
  	struct mbuf_list    ml = MBUF_LIST_INITIALIZER();
  	struct mbuf	    *m;
  	u_int8_t	    accept_frame = 0;
  	u_int8_t	    eop = 0;
  	u_int16_t	    len, desc_len, prev_len_adj;
  	int		    i, rv = 0;
  
  	/* Pointer to the receive descriptor being examined. */
  	struct em_rx_desc   *desc;
  	struct em_packet    *pkt;
  	u_int8_t	    status;
  
  	if (if_rxr_inuse(&sc->sc_rx_ring) == 0)
  		return (0);
  
  	i = sc->sc_rx_desc_tail;
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_POSTREAD);
  
  	do {
  		m = NULL;
  
  		pkt = &sc->sc_rx_pkts_ring[i];
  		desc = &sc->sc_rx_desc_ring[i];
  
  		status = desc->status;
  		if (!ISSET(status, E1000_RXD_STAT_DD))
  			break;
  
  		/* pull the mbuf off the ring */
  		bus_dmamap_sync(sc->sc_dmat, pkt->pkt_map,
  		    0, pkt->pkt_map->dm_mapsize,
  		    BUS_DMASYNC_POSTREAD);
  		bus_dmamap_unload(sc->sc_dmat, pkt->pkt_map);
  		m = pkt->pkt_m;
  		pkt->pkt_m = NULL;
  
  		KASSERT(m != NULL);
  
  		if_rxr_put(&sc->sc_rx_ring, 1);
  		rv = 1;
  
  		accept_frame = 1;
  		prev_len_adj = 0;
  		desc_len = letoh16(desc->length);
  
  		if (status & E1000_RXD_STAT_EOP) {
  			eop = 1;
  			if (desc_len < ETHER_CRC_LEN) {
  				len = 0;
  				prev_len_adj = ETHER_CRC_LEN - desc_len;
  			} else if (sc->hw.mac_type == em_i210 ||
  			    sc->hw.mac_type == em_i350)
  				len = desc_len;
  			else
  				len = desc_len - ETHER_CRC_LEN;
  		} else {
  			eop = 0;
  			len = desc_len;
  		}
  
  		if (desc->errors & E1000_RXD_ERR_FRAME_ERR_MASK) {
  			u_int8_t last_byte;
  			u_int32_t pkt_len = desc_len;
  
  			if (sc->fmp != NULL)
  				pkt_len += sc->fmp->m_pkthdr.len; 
  
  			last_byte = *(mtod(m, caddr_t) + desc_len - 1);
  			if (TBI_ACCEPT(&sc->hw, status, desc->errors,
  			    pkt_len, last_byte)) {
  #ifndef SMALL_KERNEL
  				em_tbi_adjust_stats(&sc->hw, &sc->stats, 
  				    pkt_len, sc->hw.mac_addr);
  #endif
  				if (len > 0)
  					len--;
  			} else
  				accept_frame = 0;
  		}
  
  		if (accept_frame) {
  			/* Assign correct length to the current fragment */
  			m->m_len = len;
  
  			if (sc->fmp == NULL) {
  				m->m_pkthdr.len = m->m_len;
  				sc->fmp = m;	 /* Store the first mbuf */
  				sc->lmp = m;
  			} else {
  				/* Chain mbuf's together */
  				m->m_flags &= ~M_PKTHDR;
  				/*
  				 * Adjust length of previous mbuf in chain if
  				 * we received less than 4 bytes in the last
  				 * descriptor.
  				 */
  				if (prev_len_adj > 0) {
  					sc->lmp->m_len -= prev_len_adj;
  					sc->fmp->m_pkthdr.len -= prev_len_adj;
  				}
  				sc->lmp->m_next = m;
  				sc->lmp = m;
  				sc->fmp->m_pkthdr.len += m->m_len;
  			}
  
  			if (eop) {
  				m = sc->fmp;
  
  				em_receive_checksum(sc, desc, m);
  #if NVLAN > 0
  				if (desc->status & E1000_RXD_STAT_VP) {
  					m->m_pkthdr.ether_vtag =
  					    letoh16(desc->special);
  					m->m_flags |= M_VLANTAG;
  				}
  #endif
  				ml_enqueue(&ml, m);
  
  				sc->fmp = NULL;
  				sc->lmp = NULL;
  			}
  		} else {
  			sc->dropped_pkts++;
  
  			if (sc->fmp != NULL) {
  				m_freem(sc->fmp);
  				sc->fmp = NULL;
  				sc->lmp = NULL;
  			}
  
  			m_freem(m);
  		}
  
  		/* Advance our pointers to the next descriptor. */
  		if (++i == sc->sc_rx_slots)
  			i = 0;
  	} while (if_rxr_inuse(&sc->sc_rx_ring) > 0);
  
  	bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_dma.dma_map,
  	    0, sc->sc_rx_dma.dma_map->dm_mapsize,
  	    BUS_DMASYNC_PREREAD);
  
  	sc->sc_rx_desc_tail = i;
  
  	if_input(ifp, &ml);
  
  	return (rv);
  }
  
  /*********************************************************************
   *
   *  Verify that the hardware indicated that the checksum is valid. 
   *  Inform the stack about the status of checksum so that stack
   *  doesn't spend time verifying the checksum.
   *
   *********************************************************************/
  void
  em_receive_checksum(struct em_softc *sc, struct em_rx_desc *rx_desc,
      struct mbuf *mp)
  {
  	/* 82543 or newer only */
  	if ((sc->hw.mac_type < em_82543) ||
  	    /* Ignore Checksum bit is set */
  	    (rx_desc->status & E1000_RXD_STAT_IXSM)) {
  		mp->m_pkthdr.csum_flags = 0;
  		return;
  	}
  
  	if (rx_desc->status & E1000_RXD_STAT_IPCS) {
  		/* Did it pass? */
  		if (!(rx_desc->errors & E1000_RXD_ERR_IPE)) {
  			/* IP Checksum Good */
  			mp->m_pkthdr.csum_flags = M_IPV4_CSUM_IN_OK;
  
  		} else
  			mp->m_pkthdr.csum_flags = 0;
  	}
  
  	if (rx_desc->status & E1000_RXD_STAT_TCPCS) {
  		/* Did it pass? */        
  		if (!(rx_desc->errors & E1000_RXD_ERR_TCPE))
  			mp->m_pkthdr.csum_flags |=
  				M_TCP_CSUM_IN_OK | M_UDP_CSUM_IN_OK;
  	}
  }
  
  /*
   * This turns on the hardware offload of the VLAN
   * tag insertion and strip
   */
  void 
  em_enable_hw_vlans(struct em_softc *sc)
  {
  	uint32_t ctrl;
  
  	ctrl = E1000_READ_REG(&sc->hw, CTRL);
  	ctrl |= E1000_CTRL_VME;
  	E1000_WRITE_REG(&sc->hw, CTRL, ctrl);
  }
  
  void
  em_enable_intr(struct em_softc *sc)
  {
  	E1000_WRITE_REG(&sc->hw, IMS, (IMS_ENABLE_MASK));
  }
  
  void
  em_disable_intr(struct em_softc *sc)
  {
  	/*
  	 * The first version of 82542 had an errata where when link
  	 * was forced it would stay up even if the cable was disconnected
  	 * Sequence errors were used to detect the disconnect and then
  	 * the driver would unforce the link.  This code is in the ISR.
  	 * For this to work correctly the Sequence error interrupt had
  	 * to be enabled all the time.
  	 */
  
  	if (sc->hw.mac_type == em_82542_rev2_0)
  		E1000_WRITE_REG(&sc->hw, IMC, (0xffffffff & ~E1000_IMC_RXSEQ));
  	else
  		E1000_WRITE_REG(&sc->hw, IMC, 0xffffffff);
  }
  
  void
  em_write_pci_cfg(struct em_hw *hw, uint32_t reg, uint16_t *value)
  {
  	struct pci_attach_args *pa = &((struct em_osdep *)hw->back)->em_pa;
  	pcireg_t val;
  
  	val = pci_conf_read(pa->pa_pc, pa->pa_tag, reg & ~0x3);
  	if (reg & 0x2) {
  		val &= 0x0000ffff;
  		val |= (*value << 16);
  	} else {
  		val &= 0xffff0000;
  		val |= *value;
  	}
  	pci_conf_write(pa->pa_pc, pa->pa_tag, reg & ~0x3, val);
  }
  
  void
  em_read_pci_cfg(struct em_hw *hw, uint32_t reg, uint16_t *value)
  {
  	struct pci_attach_args *pa = &((struct em_osdep *)hw->back)->em_pa;
  	pcireg_t val;
  
  	val = pci_conf_read(pa->pa_pc, pa->pa_tag, reg & ~0x3);
  	if (reg & 0x2)
  		*value = (val >> 16) & 0xffff;
  	else
  		*value = val & 0xffff;
  }
  
  void
  em_pci_set_mwi(struct em_hw *hw)
  {
  	struct pci_attach_args *pa = &((struct em_osdep *)hw->back)->em_pa;
  
  	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
  		(hw->pci_cmd_word | CMD_MEM_WRT_INVALIDATE));
  }
  
  void
  em_pci_clear_mwi(struct em_hw *hw)
  {
  	struct pci_attach_args *pa = &((struct em_osdep *)hw->back)->em_pa;
  
  	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
  		(hw->pci_cmd_word & ~CMD_MEM_WRT_INVALIDATE));
  }
  
  /*
   * We may eventually really do this, but its unnecessary
   * for now so we just return unsupported.
   */
  int32_t
  em_read_pcie_cap_reg(struct em_hw *hw, uint32_t reg, uint16_t *value)
  {
  	return -E1000_NOT_IMPLEMENTED;
  }
  
  /*********************************************************************
  * 82544 Coexistence issue workaround.
  *    There are 2 issues.
  *       1. Transmit Hang issue.
  *    To detect this issue, following equation can be used...
  *          SIZE[3:0] + ADDR[2:0] = SUM[3:0].
  *          If SUM[3:0] is in between 1 to 4, we will have this issue.
  *
  *       2. DAC issue.
  *    To detect this issue, following equation can be used...
  *          SIZE[3:0] + ADDR[2:0] = SUM[3:0].
  *          If SUM[3:0] is in between 9 to c, we will have this issue.
  *
  *
  *    WORKAROUND:
  *          Make sure we do not have ending address as 1,2,3,4(Hang) or 9,a,b,c (DAC)
  *
  *** *********************************************************************/
  u_int32_t
  em_fill_descriptors(u_int64_t address, u_int32_t length,
      PDESC_ARRAY desc_array)
  {
          /* Since issue is sensitive to length and address.*/
          /* Let us first check the address...*/
          u_int32_t safe_terminator;
          if (length <= 4) {
                  desc_array->descriptor[0].address = address;
                  desc_array->descriptor[0].length = length;
                  desc_array->elements = 1;
                  return desc_array->elements;
          }
          safe_terminator = (u_int32_t)((((u_int32_t)address & 0x7) + (length & 0xF)) & 0xF);
          /* if it does not fall between 0x1 to 0x4 and 0x9 to 0xC then return */
          if (safe_terminator == 0   ||
          (safe_terminator > 4   &&
          safe_terminator < 9)   ||
          (safe_terminator > 0xC &&
          safe_terminator <= 0xF)) {
                  desc_array->descriptor[0].address = address;
                  desc_array->descriptor[0].length = length;
                  desc_array->elements = 1;
                  return desc_array->elements;
          }
  
          desc_array->descriptor[0].address = address;
          desc_array->descriptor[0].length = length - 4;
          desc_array->descriptor[1].address = address + (length - 4);
          desc_array->descriptor[1].length = 4;
          desc_array->elements = 2;
          return desc_array->elements;
  }
  
  /*
   * Disable the L0S and L1 LINK states.
   */
  void
  em_disable_aspm(struct em_softc *sc)
  {
  	int offset;
  	pcireg_t val;
  
  	switch (sc->hw.mac_type) {
  		case em_82571:
  		case em_82572:
  		case em_82573:
  		case em_82574:
  			break;
  		default:
  			return;
  	}
  
  	if (!pci_get_capability(sc->osdep.em_pa.pa_pc, sc->osdep.em_pa.pa_tag,
  	    PCI_CAP_PCIEXPRESS, &offset, NULL))
  		return;
  
  	/* Disable PCIe Active State Power Management (ASPM). */
  	val = pci_conf_read(sc->osdep.em_pa.pa_pc, sc->osdep.em_pa.pa_tag,
  	    offset + PCI_PCIE_LCSR);
  
  	switch (sc->hw.mac_type) {
  		case em_82571:
  		case em_82572:
  			val &= ~PCI_PCIE_LCSR_ASPM_L1;
  			break;
  		case em_82573:
  		case em_82574:
  			val &= ~(PCI_PCIE_LCSR_ASPM_L0S |
  			    PCI_PCIE_LCSR_ASPM_L1);
  			break;
  		default:
  			break;
  	}
  
  	pci_conf_write(sc->osdep.em_pa.pa_pc, sc->osdep.em_pa.pa_tag,
  	    offset + PCI_PCIE_LCSR, val);
  }
  
  /*
   * em_flush_tx_ring - remove all descriptors from the tx_ring
   *
   * We want to clear all pending descriptors from the TX ring.
   * zeroing happens when the HW reads the regs. We assign the ring itself as
   * the data of the next descriptor. We don't care about the data we are about
   * to reset the HW.
   */
  void
  em_flush_tx_ring(struct em_softc *sc)
  {
  	uint32_t		 tctl, txd_lower = E1000_TXD_CMD_IFCS;
  	uint16_t		 size = 512;
  	struct em_tx_desc	*txd;
  
  	KASSERT(sc->sc_tx_desc_ring != NULL);
  
  	tctl = EM_READ_REG(&sc->hw, E1000_TCTL);
  	EM_WRITE_REG(&sc->hw, E1000_TCTL, tctl | E1000_TCTL_EN);
  
  	KASSERT(EM_READ_REG(&sc->hw, E1000_TDT) == sc->sc_tx_desc_head);
  
  	txd = &sc->sc_tx_desc_ring[sc->sc_tx_desc_head];
  	txd->buffer_addr = sc->sc_tx_dma.dma_map->dm_segs[0].ds_addr;
  	txd->lower.data = htole32(txd_lower | size);
  	txd->upper.data = 0;
  
  	/* flush descriptors to memory before notifying the HW */
  	bus_space_barrier(sc->osdep.mem_bus_space_tag,
  	    sc->osdep.mem_bus_space_handle, 0, 0, BUS_SPACE_BARRIER_WRITE);
  
  	if (++sc->sc_tx_desc_head == sc->sc_tx_slots)
  		sc->sc_tx_desc_head = 0;
  
  	EM_WRITE_REG(&sc->hw, E1000_TDT, sc->sc_tx_desc_head);
  	bus_space_barrier(sc->osdep.mem_bus_space_tag, sc->osdep.mem_bus_space_handle,
  	    0, 0, BUS_SPACE_BARRIER_READ|BUS_SPACE_BARRIER_WRITE);
  	usec_delay(250);
  }
  
  /*
   * em_flush_rx_ring - remove all descriptors from the rx_ring
   *
   * Mark all descriptors in the RX ring as consumed and disable the rx ring
   */
  void
  em_flush_rx_ring(struct em_softc *sc)
  {
  	uint32_t	rctl, rxdctl;
  
  	rctl = EM_READ_REG(&sc->hw, E1000_RCTL);
  	EM_WRITE_REG(&sc->hw, E1000_RCTL, rctl & ~E1000_RCTL_EN);
  	E1000_WRITE_FLUSH(&sc->hw);
  	usec_delay(150);
  
  	rxdctl = EM_READ_REG(&sc->hw, E1000_RXDCTL);
  	/* zero the lower 14 bits (prefetch and host thresholds) */
  	rxdctl &= 0xffffc000;
  	/*
  	 * update thresholds: prefetch threshold to 31, host threshold to 1
  	 * and make sure the granularity is "descriptors" and not "cache lines"
  	 */
  	rxdctl |= (0x1F | (1 << 8) | E1000_RXDCTL_THRESH_UNIT_DESC);
  	EM_WRITE_REG(&sc->hw, E1000_RXDCTL, rxdctl);
  
  	/* momentarily enable the RX ring for the changes to take effect */
  	EM_WRITE_REG(&sc->hw, E1000_RCTL, rctl | E1000_RCTL_EN);
  	E1000_WRITE_FLUSH(&sc->hw);
  	usec_delay(150);
  	EM_WRITE_REG(&sc->hw, E1000_RCTL, rctl & ~E1000_RCTL_EN);
  }
  
  /*
   * em_flush_desc_rings - remove all descriptors from the descriptor rings
   *
   * In i219, the descriptor rings must be emptied before resetting the HW
   * or before changing the device state to D3 during runtime (runtime PM).
   *
   * Failure to do this will cause the HW to enter a unit hang state which can
   * only be released by PCI reset on the device
   *
   */
  void
  em_flush_desc_rings(struct em_softc *sc)
  {
  	struct pci_attach_args	*pa = &sc->osdep.em_pa;
  	uint32_t		 fextnvm11, tdlen;
  	uint16_t		 hang_state;
  
  	/* First, disable MULR fix in FEXTNVM11 */
  	fextnvm11 = EM_READ_REG(&sc->hw, E1000_FEXTNVM11);
  	fextnvm11 |= E1000_FEXTNVM11_DISABLE_MULR_FIX;
  	EM_WRITE_REG(&sc->hw, E1000_FEXTNVM11, fextnvm11);
  
  	/* do nothing if we're not in faulty state, or if the queue is empty */
  	tdlen = EM_READ_REG(&sc->hw, E1000_TDLEN);
  	hang_state = pci_conf_read(pa->pa_pc, pa->pa_tag, PCICFG_DESC_RING_STATUS);
  	if (!(hang_state & FLUSH_DESC_REQUIRED) || !tdlen)
  		return;
  	em_flush_tx_ring(sc);
  
  	/* recheck, maybe the fault is caused by the rx ring */
  	hang_state = pci_conf_read(pa->pa_pc, pa->pa_tag, PCICFG_DESC_RING_STATUS);
  	if (hang_state & FLUSH_DESC_REQUIRED)
  		em_flush_rx_ring(sc);
  }
  
  #ifndef SMALL_KERNEL
  /**********************************************************************
   *
   *  Update the board statistics counters. 
   *
   **********************************************************************/
  void
  em_update_stats_counters(struct em_softc *sc)
  {
  	struct ifnet   *ifp = &sc->sc_ac.ac_if;
  
  	sc->stats.crcerrs += E1000_READ_REG(&sc->hw, CRCERRS);
  	sc->stats.mpc += E1000_READ_REG(&sc->hw, MPC);
  	sc->stats.ecol += E1000_READ_REG(&sc->hw, ECOL);
  
  	sc->stats.latecol += E1000_READ_REG(&sc->hw, LATECOL);
  	sc->stats.colc += E1000_READ_REG(&sc->hw, COLC);
  
  	sc->stats.ruc += E1000_READ_REG(&sc->hw, RUC);
  	sc->stats.roc += E1000_READ_REG(&sc->hw, ROC);
  
  	if (sc->hw.mac_type >= em_82543) {
  		sc->stats.algnerrc += 
  		E1000_READ_REG(&sc->hw, ALGNERRC);
  		sc->stats.rxerrc += 
  		E1000_READ_REG(&sc->hw, RXERRC);
  		sc->stats.cexterr += 
  		E1000_READ_REG(&sc->hw, CEXTERR);
  	}
  
  #ifdef EM_DEBUG
  	if (sc->hw.media_type == em_media_type_copper ||
  	    (E1000_READ_REG(&sc->hw, STATUS) & E1000_STATUS_LU)) {
  		sc->stats.symerrs += E1000_READ_REG(&sc->hw, SYMERRS);
  		sc->stats.sec += E1000_READ_REG(&sc->hw, SEC);
  	}
  	sc->stats.scc += E1000_READ_REG(&sc->hw, SCC);
  
  	sc->stats.mcc += E1000_READ_REG(&sc->hw, MCC);
  	sc->stats.dc += E1000_READ_REG(&sc->hw, DC);
  	sc->stats.rlec += E1000_READ_REG(&sc->hw, RLEC);
  	sc->stats.xonrxc += E1000_READ_REG(&sc->hw, XONRXC);
  	sc->stats.xontxc += E1000_READ_REG(&sc->hw, XONTXC);
  	sc->stats.xoffrxc += E1000_READ_REG(&sc->hw, XOFFRXC);
  	sc->stats.xofftxc += E1000_READ_REG(&sc->hw, XOFFTXC);
  	sc->stats.fcruc += E1000_READ_REG(&sc->hw, FCRUC);
  	sc->stats.prc64 += E1000_READ_REG(&sc->hw, PRC64);
  	sc->stats.prc127 += E1000_READ_REG(&sc->hw, PRC127);
  	sc->stats.prc255 += E1000_READ_REG(&sc->hw, PRC255);
  	sc->stats.prc511 += E1000_READ_REG(&sc->hw, PRC511);
  	sc->stats.prc1023 += E1000_READ_REG(&sc->hw, PRC1023);
  	sc->stats.prc1522 += E1000_READ_REG(&sc->hw, PRC1522);
  	sc->stats.gprc += E1000_READ_REG(&sc->hw, GPRC);
  	sc->stats.bprc += E1000_READ_REG(&sc->hw, BPRC);
  	sc->stats.mprc += E1000_READ_REG(&sc->hw, MPRC);
  	sc->stats.gptc += E1000_READ_REG(&sc->hw, GPTC);
  
  	/* For the 64-bit byte counters the low dword must be read first. */
  	/* Both registers clear on the read of the high dword */
  
  	sc->stats.gorcl += E1000_READ_REG(&sc->hw, GORCL); 
  	sc->stats.gorch += E1000_READ_REG(&sc->hw, GORCH);
  	sc->stats.gotcl += E1000_READ_REG(&sc->hw, GOTCL);
  	sc->stats.gotch += E1000_READ_REG(&sc->hw, GOTCH);
  
  	sc->stats.rnbc += E1000_READ_REG(&sc->hw, RNBC);
  	sc->stats.rfc += E1000_READ_REG(&sc->hw, RFC);
  	sc->stats.rjc += E1000_READ_REG(&sc->hw, RJC);
  
  	sc->stats.torl += E1000_READ_REG(&sc->hw, TORL);
  	sc->stats.torh += E1000_READ_REG(&sc->hw, TORH);
  	sc->stats.totl += E1000_READ_REG(&sc->hw, TOTL);
  	sc->stats.toth += E1000_READ_REG(&sc->hw, TOTH);
  
  	sc->stats.tpr += E1000_READ_REG(&sc->hw, TPR);
  	sc->stats.tpt += E1000_READ_REG(&sc->hw, TPT);
  	sc->stats.ptc64 += E1000_READ_REG(&sc->hw, PTC64);
  	sc->stats.ptc127 += E1000_READ_REG(&sc->hw, PTC127);
  	sc->stats.ptc255 += E1000_READ_REG(&sc->hw, PTC255);
  	sc->stats.ptc511 += E1000_READ_REG(&sc->hw, PTC511);
  	sc->stats.ptc1023 += E1000_READ_REG(&sc->hw, PTC1023);
  	sc->stats.ptc1522 += E1000_READ_REG(&sc->hw, PTC1522);
  	sc->stats.mptc += E1000_READ_REG(&sc->hw, MPTC);
  	sc->stats.bptc += E1000_READ_REG(&sc->hw, BPTC);
  
  	if (sc->hw.mac_type >= em_82543) {
  		sc->stats.tncrs += 
  		E1000_READ_REG(&sc->hw, TNCRS);
  		sc->stats.tsctc += 
  		E1000_READ_REG(&sc->hw, TSCTC);
  		sc->stats.tsctfc += 
  		E1000_READ_REG(&sc->hw, TSCTFC);
  	}
  #endif
  
  	/* Fill out the OS statistics structure */
  	ifp->if_collisions = sc->stats.colc;
  
  	/* Rx Errors */
  	ifp->if_ierrors =
  	    sc->dropped_pkts +
  	    sc->stats.rxerrc +
  	    sc->stats.crcerrs +
  	    sc->stats.algnerrc +
  	    sc->stats.ruc + sc->stats.roc +
  	    sc->stats.mpc + sc->stats.cexterr +
  	    sc->rx_overruns;
  
  	/* Tx Errors */
  	ifp->if_oerrors = sc->stats.ecol + sc->stats.latecol +
  	    sc->watchdog_events;
  }
  
  #ifdef EM_DEBUG
  /**********************************************************************
   *
   *  This routine is called only when IFF_DEBUG is enabled.
   *  This routine provides a way to take a look at important statistics
   *  maintained by the driver and hardware.
   *
   **********************************************************************/
  void
  em_print_hw_stats(struct em_softc *sc)
  {
  	const char * const unit = DEVNAME(sc);
  
  	printf("%s: Excessive collisions = %lld\n", unit,
  		(long long)sc->stats.ecol);
  	printf("%s: Symbol errors = %lld\n", unit,
  		(long long)sc->stats.symerrs);
  	printf("%s: Sequence errors = %lld\n", unit,
  		(long long)sc->stats.sec);
  	printf("%s: Defer count = %lld\n", unit,
  		(long long)sc->stats.dc);
  
  	printf("%s: Missed Packets = %lld\n", unit,
  		(long long)sc->stats.mpc);
  	printf("%s: Receive No Buffers = %lld\n", unit,
  		(long long)sc->stats.rnbc);
  	/* RLEC is inaccurate on some hardware, calculate our own */
  	printf("%s: Receive Length Errors = %lld\n", unit,
  		((long long)sc->stats.roc +
  		(long long)sc->stats.ruc));
  	printf("%s: Receive errors = %lld\n", unit,
  		(long long)sc->stats.rxerrc);
  	printf("%s: Crc errors = %lld\n", unit,
  		(long long)sc->stats.crcerrs);
  	printf("%s: Alignment errors = %lld\n", unit,
  		(long long)sc->stats.algnerrc);
  	printf("%s: Carrier extension errors = %lld\n", unit,
  		(long long)sc->stats.cexterr);
  
  	printf("%s: RX overruns = %ld\n", unit,
  		sc->rx_overruns);
  	printf("%s: watchdog timeouts = %ld\n", unit,
  		sc->watchdog_events);
  
  	printf("%s: XON Rcvd = %lld\n", unit,
  		(long long)sc->stats.xonrxc);
  	printf("%s: XON Xmtd = %lld\n", unit,
  		(long long)sc->stats.xontxc);
  	printf("%s: XOFF Rcvd = %lld\n", unit,
  		(long long)sc->stats.xoffrxc);
  	printf("%s: XOFF Xmtd = %lld\n", unit,
  		(long long)sc->stats.xofftxc);
  
  	printf("%s: Good Packets Rcvd = %lld\n", unit,
  		(long long)sc->stats.gprc);
  	printf("%s: Good Packets Xmtd = %lld\n", unit,
  		(long long)sc->stats.gptc);
  }
  #endif
  #endif /* !SMALL_KERNEL */
  