freebsd-nq/sys/dev/em/if_em.c

/**************************************************************************

Copyright (c) 2001-2005, 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.

***************************************************************************/

/*$FreeBSD$*/

#ifdef HAVE_KERNEL_OPTION_HEADERS
#include "opt_device_polling.h"
#endif

#include <dev/em/if_em.h>

/*********************************************************************
 *  Set this to one to display debug statistics                                                   
 *********************************************************************/
int             em_display_debug_stats = 0;

/*********************************************************************
 *  Driver version
 *********************************************************************/

char em_driver_version[] = "Version - 3.2.18";


/*********************************************************************
 *  PCI Device ID Table
 *
 *  Used by probe to select devices to load on
 *  Last field stores an index into em_strings
 *  Last entry must be all 0s
 *
 *  { Vendor ID, Device ID, SubVendor ID, SubDevice ID, String Index }
 *********************************************************************/

static em_vendor_info_t em_vendor_info_array[] =
{
        /* Intel(R) PRO/1000 Network Connection */
        { 0x8086, E1000_DEV_ID_82540EM,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82540EM_LOM,         PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82540EP,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82540EP_LOM,         PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82540EP_LP,          PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82541EI,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541ER,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541ER_LOM,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541EI_MOBILE,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541GI,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541GI_LF,          PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82541GI_MOBILE,      PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82542,               PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82543GC_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82543GC_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82544EI_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82544EI_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82544GC_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82544GC_LOM,         PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82545EM_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82545EM_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82545GM_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82545GM_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82545GM_SERDES,      PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82546EB_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546EB_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546EB_QUAD_COPPER, PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546GB_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546GB_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546GB_SERDES,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546GB_PCIE,        PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82546GB_QUAD_COPPER, PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82547EI,             PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82547EI_MOBILE,      PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82547GI,             PCI_ANY_ID, PCI_ANY_ID, 0},

	{ 0x8086, E1000_DEV_ID_82571EB_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
	{ 0x8086, E1000_DEV_ID_82571EB_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
	{ 0x8086, E1000_DEV_ID_82571EB_SERDES,      PCI_ANY_ID, PCI_ANY_ID, 0},

	{ 0x8086, E1000_DEV_ID_82572EI_COPPER,      PCI_ANY_ID, PCI_ANY_ID, 0},
	{ 0x8086, E1000_DEV_ID_82572EI_FIBER,       PCI_ANY_ID, PCI_ANY_ID, 0},
	{ 0x8086, E1000_DEV_ID_82572EI_SERDES,      PCI_ANY_ID, PCI_ANY_ID, 0},

        { 0x8086, E1000_DEV_ID_82573E,              PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82573E_IAMT,         PCI_ANY_ID, PCI_ANY_ID, 0},
        { 0x8086, E1000_DEV_ID_82573L,              PCI_ANY_ID, PCI_ANY_ID, 0},

        /* required last entry */
        { 0, 0, 0, 0, 0}
};

/*********************************************************************
 *  Table of branding strings for all supported NICs.
 *********************************************************************/

static char *em_strings[] = {
	"Intel(R) PRO/1000 Network Connection"
};

/*********************************************************************
 *  Function prototypes            
 *********************************************************************/
static int  em_probe(device_t);
static int  em_attach(device_t);
static int  em_detach(device_t);
static int  em_shutdown(device_t);
static int  em_suspend(device_t);
static int  em_resume(device_t);
static void em_intr(void *);
#ifndef NO_EM_FASTINTR
static void em_intr_fast(void *);
#endif
static void em_start(struct ifnet *);
static void em_start_locked(struct ifnet *ifp);
static int  em_ioctl(struct ifnet *, u_long, caddr_t);
static void em_watchdog(struct ifnet *);
static void em_init(void *);
static void em_init_locked(struct adapter *);
static void em_stop(void *);
static void em_media_status(struct ifnet *, struct ifmediareq *);
static int  em_media_change(struct ifnet *);
static void em_identify_hardware(struct adapter *);
static int  em_allocate_pci_resources(struct adapter *);
static void em_free_pci_resources(struct adapter *);
static void em_local_timer(void *);
static int  em_hardware_init(struct adapter *);
static void em_setup_interface(device_t, struct adapter *);
static int  em_setup_transmit_structures(struct adapter *);
static void em_initialize_transmit_unit(struct adapter *);
static int  em_setup_receive_structures(struct adapter *);
static void em_initialize_receive_unit(struct adapter *);
static void em_enable_intr(struct adapter *);
static void em_disable_intr(struct adapter *);
static void em_free_transmit_structures(struct adapter *);
static void em_free_receive_structures(struct adapter *);
static void em_update_stats_counters(struct adapter *);
static void em_clean_transmit_interrupts(struct adapter *);
static int  em_allocate_receive_structures(struct adapter *);
static int  em_allocate_transmit_structures(struct adapter *);
static int em_process_receive_interrupts(struct adapter *, int);
#ifndef __NO_STRICT_ALIGNMENT
static int  em_fixup_rx(struct adapter *);
#endif
static void em_receive_checksum(struct adapter *, 
				struct em_rx_desc *,
				struct mbuf *);
static void em_transmit_checksum_setup(struct adapter *,
				       struct mbuf *,
				       u_int32_t *,
				       u_int32_t *);
static void em_set_promisc(struct adapter *);
static void em_disable_promisc(struct adapter *);
static void em_set_multi(struct adapter *);
static void em_print_hw_stats(struct adapter *);
static void em_print_link_status(struct adapter *);
static int  em_get_buf(int i, struct adapter *,
		       struct mbuf *);
static void em_enable_vlans(struct adapter *);
static void em_disable_vlans(struct adapter *);
static int  em_encap(struct adapter *, struct mbuf **);
static void em_smartspeed(struct adapter *);
static int  em_82547_fifo_workaround(struct adapter *, int);
static void em_82547_update_fifo_head(struct adapter *, int);
static int  em_82547_tx_fifo_reset(struct adapter *);
static void em_82547_move_tail(void *arg);
static void em_82547_move_tail_locked(struct adapter *);
static int  em_dma_malloc(struct adapter *, bus_size_t,
			  struct em_dma_alloc *, int);
static void em_dma_free(struct adapter *, struct em_dma_alloc *);
static void em_print_debug_info(struct adapter *);
static int  em_is_valid_ether_addr(u_int8_t *);
static int  em_sysctl_stats(SYSCTL_HANDLER_ARGS);
static int  em_sysctl_debug_info(SYSCTL_HANDLER_ARGS);
static u_int32_t em_fill_descriptors (bus_addr_t address, 
				      u_int32_t length, 
				      PDESC_ARRAY desc_array);
static int  em_sysctl_int_delay(SYSCTL_HANDLER_ARGS);
static void em_add_int_delay_sysctl(struct adapter *, const char *,
				    const char *, struct em_int_delay_info *,
				    int, int);
#ifndef NO_EM_FASTINTR
static void em_add_int_process_limit(struct adapter *, const char *,
				     const char *, int *, int);
static void em_handle_rxtx(void *context, int pending);
static void em_handle_link(void *context, int pending);
#endif
#ifdef DEVICE_POLLING
static poll_handler_t em_poll;
#endif

/*********************************************************************
 *  FreeBSD Device Interface Entry Points                    
 *********************************************************************/

static device_method_t em_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe, em_probe),
	DEVMETHOD(device_attach, em_attach),
	DEVMETHOD(device_detach, em_detach),
	DEVMETHOD(device_shutdown, em_shutdown),
	DEVMETHOD(device_suspend, em_suspend),
	DEVMETHOD(device_resume, em_resume),
	{0, 0}
};

static driver_t em_driver = {
	"em", em_methods, sizeof(struct adapter ),
};

static devclass_t em_devclass;
DRIVER_MODULE(em, pci, em_driver, em_devclass, 0, 0);
MODULE_DEPEND(em, pci, 1, 1, 1);
MODULE_DEPEND(em, ether, 1, 1, 1);

/*********************************************************************
 *  Tunable default values.
 *********************************************************************/

#define E1000_TICKS_TO_USECS(ticks)	((1024 * (ticks) + 500) / 1000)
#define E1000_USECS_TO_TICKS(usecs)	((1000 * (usecs) + 512) / 1024)

static int em_tx_int_delay_dflt = E1000_TICKS_TO_USECS(EM_TIDV);
static int em_rx_int_delay_dflt = E1000_TICKS_TO_USECS(EM_RDTR);
static int em_tx_abs_int_delay_dflt = E1000_TICKS_TO_USECS(EM_TADV);
static int em_rx_abs_int_delay_dflt = E1000_TICKS_TO_USECS(EM_RADV);
static int em_rxd = EM_DEFAULT_RXD;
static int em_txd = EM_DEFAULT_TXD;

TUNABLE_INT("hw.em.tx_int_delay", &em_tx_int_delay_dflt);
TUNABLE_INT("hw.em.rx_int_delay", &em_rx_int_delay_dflt);
TUNABLE_INT("hw.em.tx_abs_int_delay", &em_tx_abs_int_delay_dflt);
TUNABLE_INT("hw.em.rx_abs_int_delay", &em_rx_abs_int_delay_dflt);
TUNABLE_INT("hw.em.rxd", &em_rxd);
TUNABLE_INT("hw.em.txd", &em_txd);
#ifndef NO_EM_FASTINTR
static int em_rx_process_limit = 100;
TUNABLE_INT("hw.em.rx_process_limit", &em_rx_process_limit);
#endif

/*********************************************************************
 *  Device identification routine
 *
 *  em_probe determines if the driver should be loaded on
 *  adapter based on PCI vendor/device id of the adapter.
 *
 *  return BUS_PROBE_DEFAULT on success, positive on failure
 *********************************************************************/

static int
em_probe(device_t dev)
{
	em_vendor_info_t *ent;

	u_int16_t       pci_vendor_id = 0;
	u_int16_t       pci_device_id = 0;
	u_int16_t       pci_subvendor_id = 0;
	u_int16_t       pci_subdevice_id = 0;
	char            adapter_name[60];

	INIT_DEBUGOUT("em_probe: begin");

	pci_vendor_id = pci_get_vendor(dev);
	if (pci_vendor_id != EM_VENDOR_ID)
		return(ENXIO);

	pci_device_id = pci_get_device(dev);
	pci_subvendor_id = pci_get_subvendor(dev);
	pci_subdevice_id = pci_get_subdevice(dev);

	ent = em_vendor_info_array;
	while (ent->vendor_id != 0) {
		if ((pci_vendor_id == ent->vendor_id) &&
		    (pci_device_id == ent->device_id) &&

		    ((pci_subvendor_id == ent->subvendor_id) ||
		     (ent->subvendor_id == PCI_ANY_ID)) &&

		    ((pci_subdevice_id == ent->subdevice_id) ||
		     (ent->subdevice_id == PCI_ANY_ID))) {
			sprintf(adapter_name, "%s %s", 
				em_strings[ent->index], 
				em_driver_version);
			device_set_desc_copy(dev, adapter_name);
			return(BUS_PROBE_DEFAULT);
		}
		ent++;
	}

	return(ENXIO);
}

/*********************************************************************
 *  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.     
 *  
 *  return 0 on success, positive on failure
 *********************************************************************/

static int
em_attach(device_t dev)
{
	struct adapter * adapter;
	int             tsize, rsize;
	int		error = 0;

	INIT_DEBUGOUT("em_attach: begin");

	/* Allocate, clear, and link in our adapter structure */
	if (!(adapter = device_get_softc(dev))) {
		printf("em: adapter structure allocation failed\n");
		return(ENOMEM);
	}
	bzero(adapter, sizeof(struct adapter ));
	adapter->dev = dev;
	adapter->osdep.dev = dev;
	adapter->unit = device_get_unit(dev);
	EM_LOCK_INIT(adapter, device_get_nameunit(dev));

	/* SYSCTL stuff */
        SYSCTL_ADD_PROC(device_get_sysctl_ctx(dev),
                        SYSCTL_CHILDREN(device_get_sysctl_tree(dev)),
                        OID_AUTO, "debug_info", CTLTYPE_INT|CTLFLAG_RW,
                        (void *)adapter, 0,
                        em_sysctl_debug_info, "I", "Debug Information");
        
        SYSCTL_ADD_PROC(device_get_sysctl_ctx(dev),
                        SYSCTL_CHILDREN(device_get_sysctl_tree(dev)),
                        OID_AUTO, "stats", CTLTYPE_INT|CTLFLAG_RW,
                        (void *)adapter, 0,
                        em_sysctl_stats, "I", "Statistics");

	callout_init(&adapter->timer, CALLOUT_MPSAFE);
	callout_init(&adapter->tx_fifo_timer, CALLOUT_MPSAFE);

	/* Determine hardware revision */
	em_identify_hardware(adapter);

	/* Set up some sysctls for the tunable interrupt delays */
	em_add_int_delay_sysctl(adapter, "rx_int_delay",
	    "receive interrupt delay in usecs", &adapter->rx_int_delay,
	    E1000_REG_OFFSET(&adapter->hw, RDTR), em_rx_int_delay_dflt);
	em_add_int_delay_sysctl(adapter, "tx_int_delay",
	    "transmit interrupt delay in usecs", &adapter->tx_int_delay,
	    E1000_REG_OFFSET(&adapter->hw, TIDV), em_tx_int_delay_dflt);
	if (adapter->hw.mac_type >= em_82540) {
		em_add_int_delay_sysctl(adapter, "rx_abs_int_delay",
		    "receive interrupt delay limit in usecs",
		    &adapter->rx_abs_int_delay,
		    E1000_REG_OFFSET(&adapter->hw, RADV),
		    em_rx_abs_int_delay_dflt);
		em_add_int_delay_sysctl(adapter, "tx_abs_int_delay",
		    "transmit interrupt delay limit in usecs",
		    &adapter->tx_abs_int_delay,
		    E1000_REG_OFFSET(&adapter->hw, TADV),
		    em_tx_abs_int_delay_dflt);
	}

	/* Sysctls for limiting the amount of work done in the taskqueue */
#ifndef NO_EM_FASTINTR
	em_add_int_process_limit(adapter, "rx_processing_limit",
	    "max number of rx packets to process", &adapter->rx_process_limit,
	    em_rx_process_limit);
#endif

	/*
	 * Validate number of transmit and receive descriptors. It
	 * must not exceed hardware maximum, and must be multiple
	 * of E1000_DBA_ALIGN.
	 */
	if (((em_txd * sizeof(struct em_tx_desc)) % E1000_DBA_ALIGN) != 0 ||
	    (adapter->hw.mac_type >= em_82544 && em_txd > EM_MAX_TXD) ||
	    (adapter->hw.mac_type < em_82544 && em_txd > EM_MAX_TXD_82543) ||
	    (em_txd < EM_MIN_TXD)) {
		printf("em%d: Using %d TX descriptors instead of %d!\n",
		    adapter->unit, EM_DEFAULT_TXD, em_txd);
		adapter->num_tx_desc = EM_DEFAULT_TXD;
	} else
		adapter->num_tx_desc = em_txd;
	if (((em_rxd * sizeof(struct em_rx_desc)) % E1000_DBA_ALIGN) != 0 ||
	    (adapter->hw.mac_type >= em_82544 && em_rxd > EM_MAX_RXD) ||
	    (adapter->hw.mac_type < em_82544 && em_rxd > EM_MAX_RXD_82543) ||
	    (em_rxd < EM_MIN_RXD)) {
		printf("em%d: Using %d RX descriptors instead of %d!\n",
		    adapter->unit, EM_DEFAULT_RXD, em_rxd);
		adapter->num_rx_desc = EM_DEFAULT_RXD;
	} else
		adapter->num_rx_desc = em_rxd;

        adapter->hw.autoneg = DO_AUTO_NEG;
        adapter->hw.wait_autoneg_complete = WAIT_FOR_AUTO_NEG_DEFAULT;
        adapter->hw.autoneg_advertised = AUTONEG_ADV_DEFAULT;
        adapter->hw.tbi_compatibility_en = TRUE;
        adapter->rx_buffer_len = EM_RXBUFFER_2048;
                        
	adapter->hw.phy_init_script = 1;
	adapter->hw.phy_reset_disable = FALSE;

#ifndef EM_MASTER_SLAVE
	adapter->hw.master_slave = em_ms_hw_default;
#else
	adapter->hw.master_slave = EM_MASTER_SLAVE;
#endif
	/* 
	 * Set the max frame size assuming standard ethernet 
	 * sized frames 
	 */   
	adapter->hw.max_frame_size = 
		ETHERMTU + ETHER_HDR_LEN + ETHER_CRC_LEN;

	adapter->hw.min_frame_size = 
		MINIMUM_ETHERNET_PACKET_SIZE + ETHER_CRC_LEN;

	/* 
	 * This controls when hardware reports transmit completion 
	 * status. 
	 */
	adapter->hw.report_tx_early = 1;

	if (em_allocate_pci_resources(adapter)) {
		printf("em%d: Allocation of PCI resources failed\n", 
		       adapter->unit);
                error = ENXIO;
                goto err_pci;
	}
  
	
	/* Initialize eeprom parameters */
        em_init_eeprom_params(&adapter->hw);

	tsize = roundup2(adapter->num_tx_desc * sizeof(struct em_tx_desc),
	    E1000_DBA_ALIGN);

	/* Allocate Transmit Descriptor ring */
        if (em_dma_malloc(adapter, tsize, &adapter->txdma, BUS_DMA_NOWAIT)) {
                printf("em%d: Unable to allocate tx_desc memory\n",
                       adapter->unit);
		error = ENOMEM;
                goto err_tx_desc;
        }
        adapter->tx_desc_base = (struct em_tx_desc *) adapter->txdma.dma_vaddr;

	rsize = roundup2(adapter->num_rx_desc * sizeof(struct em_rx_desc),
	    E1000_DBA_ALIGN);

	/* Allocate Receive Descriptor ring */  
        if (em_dma_malloc(adapter, rsize, &adapter->rxdma, BUS_DMA_NOWAIT)) {
                printf("em%d: Unable to allocate rx_desc memory\n",
                        adapter->unit);
		error = ENOMEM;
                goto err_rx_desc;
        }
        adapter->rx_desc_base = (struct em_rx_desc *) adapter->rxdma.dma_vaddr;

	/* Initialize the hardware */
	if (em_hardware_init(adapter)) {
		printf("em%d: Unable to initialize the hardware\n",
		       adapter->unit);
		error = EIO;
                goto err_hw_init;
	}

	/* Copy the permanent MAC address out of the EEPROM */
	if (em_read_mac_addr(&adapter->hw) < 0) {
		printf("em%d: EEPROM read error while reading mac address\n",
		       adapter->unit);
		error = EIO;
                goto err_mac_addr;
	}

	if (!em_is_valid_ether_addr(adapter->hw.mac_addr)) {
                printf("em%d: Invalid mac address\n", adapter->unit);
                error = EIO;
                goto err_mac_addr;
        }

	/* Setup OS specific network interface */
	em_setup_interface(dev, adapter);

	/* Initialize statistics */
	em_clear_hw_cntrs(&adapter->hw);
	em_update_stats_counters(adapter);
	adapter->hw.get_link_status = 1;
	em_check_for_link(&adapter->hw);

	if (bootverbose) {
		/* Print the link status */
		if (adapter->link_active == 1) {
			em_get_speed_and_duplex(&adapter->hw,
			    &adapter->link_speed, &adapter->link_duplex);
			printf("em%d:  Speed:%d Mbps  Duplex:%s\n",
			       adapter->unit,
			       adapter->link_speed,
			       adapter->link_duplex == FULL_DUPLEX ? "Full" :
				"Half");
		} else
			printf("em%d:  Speed:N/A  Duplex:N/A\n",
			    adapter->unit);
	}

	/* Identify 82544 on PCIX */
        em_get_bus_info(&adapter->hw);
        if(adapter->hw.bus_type == em_bus_type_pcix &&
           adapter->hw.mac_type == em_82544) {
                adapter->pcix_82544 = TRUE;
        }
        else {
                adapter->pcix_82544 = FALSE;
        }
	INIT_DEBUGOUT("em_attach: end");
	return(0);

err_mac_addr:
err_hw_init:
        em_dma_free(adapter, &adapter->rxdma);
err_rx_desc:
        em_dma_free(adapter, &adapter->txdma);
err_tx_desc:
err_pci:
        em_free_pci_resources(adapter);
	EM_LOCK_DESTROY(adapter);
        return(error);

}

/*********************************************************************
 *  Device removal routine
 *
 *  The detach entry point is called when the driver is being removed.
 *  This routine stops the adapter and deallocates all the resources
 *  that were allocated for driver operation.
 *  
 *  return 0 on success, positive on failure
 *********************************************************************/

static int
em_detach(device_t dev)
{
	struct adapter * adapter = device_get_softc(dev);
	struct ifnet   *ifp = adapter->ifp;

	INIT_DEBUGOUT("em_detach: begin");

#ifdef DEVICE_POLLING
	if (ifp->if_capenable & IFCAP_POLLING)
		ether_poll_deregister(ifp);
#endif

	if (adapter->res_interrupt != NULL) {
		bus_teardown_intr(dev, adapter->res_interrupt, 
				  adapter->int_handler_tag);
		bus_release_resource(dev, SYS_RES_IRQ, 0, 
				     adapter->res_interrupt);
		adapter->res_interrupt = NULL;
		if (adapter->tq != NULL) {
			taskqueue_drain(adapter->tq, &adapter->rxtx_task);
			taskqueue_drain(taskqueue_fast, &adapter->link_task);
		}
	}
	EM_LOCK(adapter);
	adapter->in_detach = 1;
	em_stop(adapter);
	em_phy_hw_reset(&adapter->hw);
	EM_UNLOCK(adapter);
        ether_ifdetach(adapter->ifp);

	em_free_pci_resources(adapter);
	bus_generic_detach(dev);
	if_free(ifp);

	/* Free Transmit Descriptor ring */
        if (adapter->tx_desc_base) {
                em_dma_free(adapter, &adapter->txdma);
                adapter->tx_desc_base = NULL;
        }

        /* Free Receive Descriptor ring */
        if (adapter->rx_desc_base) {
                em_dma_free(adapter, &adapter->rxdma);
                adapter->rx_desc_base = NULL;
        }

	EM_LOCK_DESTROY(adapter);

	return(0);
}

/*********************************************************************
 *
 *  Shutdown entry point
 *
 **********************************************************************/ 

static int
em_shutdown(device_t dev)
{
	struct adapter *adapter = device_get_softc(dev);
	EM_LOCK(adapter);
	em_stop(adapter);
	EM_UNLOCK(adapter);
	return(0);
}

/*
 * Suspend/resume device methods.
 */
static int
em_suspend(device_t dev)
{
	struct adapter *adapter = device_get_softc(dev);

	EM_LOCK(adapter);
	em_stop(adapter);
	EM_UNLOCK(adapter);

	return bus_generic_suspend(dev);
}

static int
em_resume(device_t dev)
{
	struct adapter *adapter = device_get_softc(dev);
	struct ifnet *ifp = adapter->ifp;

	EM_LOCK(adapter);
	em_init_locked(adapter);
	if ((ifp->if_flags & IFF_UP) &&
	    (ifp->if_drv_flags & IFF_DRV_RUNNING))
		em_start_locked(ifp);
	EM_UNLOCK(adapter);

	return bus_generic_resume(dev);
}


/*********************************************************************
 *  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.
 **********************************************************************/

static void
em_start_locked(struct ifnet *ifp)
{
        struct mbuf    *m_head;
        struct adapter *adapter = ifp->if_softc;

	mtx_assert(&adapter->mtx, MA_OWNED);

        if (!adapter->link_active)
                return;

        while (!IFQ_DRV_IS_EMPTY(&ifp->if_snd)) {

                IFQ_DRV_DEQUEUE(&ifp->if_snd, m_head);
                
                if (m_head == NULL) break;

		/*
		 * em_encap() can modify our pointer, and or make it NULL on
		 * failure.  In that event, we can't requeue.
		 */
		if (em_encap(adapter, &m_head)) { 
			if (m_head == NULL)
				break;
			ifp->if_drv_flags |= IFF_DRV_OACTIVE;
			IFQ_DRV_PREPEND(&ifp->if_snd, m_head);
			break;
                }

		/* Send a copy of the frame to the BPF listener */
		BPF_MTAP(ifp, m_head);
        
                /* Set timeout in case hardware has problems transmitting */
                ifp->if_timer = EM_TX_TIMEOUT;
        
        }
        return;
}

static void
em_start(struct ifnet *ifp)
{
	struct adapter *adapter = ifp->if_softc;

	EM_LOCK(adapter);
	if (ifp->if_drv_flags & IFF_DRV_RUNNING)
		em_start_locked(ifp);
	EM_UNLOCK(adapter);
	return;
}

/*********************************************************************
 *  Ioctl entry point
 *
 *  em_ioctl is called when the user wants to configure the
 *  interface.
 *
 *  return 0 on success, positive on failure
 **********************************************************************/

static int
em_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
{
	struct ifreq   *ifr = (struct ifreq *) data;
	struct adapter * adapter = ifp->if_softc;
	int error = 0;

	if (adapter->in_detach) return(error);

	switch (command) {
	case SIOCSIFADDR:
	case SIOCGIFADDR:
		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCxIFADDR (Get/Set Interface Addr)");
		ether_ioctl(ifp, command, data);
		break;
	case SIOCSIFMTU:
	    {
		int max_frame_size;

		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCSIFMTU (Set Interface MTU)");

		switch (adapter->hw.mac_type) {
		case em_82571:
		case em_82572:
			max_frame_size = 10500;
			break;
		case em_82573:
			/* 82573 does not support jumbo frames. */
			max_frame_size = ETHER_MAX_LEN;
			break;
		default:
			max_frame_size = MAX_JUMBO_FRAME_SIZE;
		}
		if (ifr->ifr_mtu > max_frame_size - ETHER_HDR_LEN -
		    ETHER_CRC_LEN) {
			error = EINVAL;
			break;
		}

		EM_LOCK(adapter);
		ifp->if_mtu = ifr->ifr_mtu;
		adapter->hw.max_frame_size = 
		ifp->if_mtu + ETHER_HDR_LEN + ETHER_CRC_LEN;
		em_init_locked(adapter);
		EM_UNLOCK(adapter);
		break;
	    }
	case SIOCSIFFLAGS:
		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCSIFFLAGS (Set Interface Flags)");
		EM_LOCK(adapter);
		if (ifp->if_flags & IFF_UP) {
			if (!(ifp->if_drv_flags & IFF_DRV_RUNNING)) {
				em_init_locked(adapter);
			}

			em_disable_promisc(adapter);
			em_set_promisc(adapter);
		} else {
			if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
				em_stop(adapter);
			}
		}
		EM_UNLOCK(adapter);
		break;
	case SIOCADDMULTI:
	case SIOCDELMULTI:
		IOCTL_DEBUGOUT("ioctl rcv'd: SIOC(ADD|DEL)MULTI");
		if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
			EM_LOCK(adapter);
			em_disable_intr(adapter);
			em_set_multi(adapter);
			if (adapter->hw.mac_type == em_82542_rev2_0) {
				em_initialize_receive_unit(adapter);
			}
#ifdef DEVICE_POLLING
                        if (!(ifp->if_capenable & IFCAP_POLLING))
#endif
				em_enable_intr(adapter);
			EM_UNLOCK(adapter);
		}
		break;
	case SIOCSIFMEDIA:
	case SIOCGIFMEDIA:
		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCxIFMEDIA (Get/Set Interface Media)");
		error = ifmedia_ioctl(ifp, ifr, &adapter->media, command);
		break;
	case SIOCSIFCAP:
	    {
		int mask, reinit;

		IOCTL_DEBUGOUT("ioctl rcv'd: SIOCSIFCAP (Set Capabilities)");
		reinit = 0;
		mask = ifr->ifr_reqcap ^ ifp->if_capenable;
#ifdef DEVICE_POLLING
		if (mask & IFCAP_POLLING) {
			if (ifr->ifr_reqcap & IFCAP_POLLING) {
				error = ether_poll_register(em_poll, ifp);
				if (error)
					return(error);
				EM_LOCK(adapter);
				em_disable_intr(adapter);
				ifp->if_capenable |= IFCAP_POLLING;
				EM_UNLOCK(adapter);
			} else {
				error = ether_poll_deregister(ifp);
				/* Enable interrupt even in error case */
				EM_LOCK(adapter);
				em_enable_intr(adapter);
				ifp->if_capenable &= ~IFCAP_POLLING;
				EM_UNLOCK(adapter);
			}
		}
#endif
		if (mask & IFCAP_HWCSUM) {
			ifp->if_capenable ^= IFCAP_HWCSUM;
			reinit = 1;
		}
		if (mask & IFCAP_VLAN_HWTAGGING) {
			ifp->if_capenable ^= IFCAP_VLAN_HWTAGGING;
			reinit = 1;
		}
		if (reinit && (ifp->if_drv_flags & IFF_DRV_RUNNING))
			em_init(adapter);
		break;
	    }
	default:
		IOCTL_DEBUGOUT1("ioctl received: UNKNOWN (0x%x)", (int)command);
		error = EINVAL;
	}

	return(error);
}

/*********************************************************************
 *  Watchdog entry point
 *
 *  This routine is called whenever hardware quits transmitting.
 *
 **********************************************************************/

static void
em_watchdog(struct ifnet *ifp)
{
	struct adapter * adapter;
	adapter = ifp->if_softc;

	EM_LOCK(adapter);
	/* If we are in this routine because of pause frames, then
	 * don't reset the hardware.
	 */
	if (E1000_READ_REG(&adapter->hw, STATUS) & E1000_STATUS_TXOFF) {
		ifp->if_timer = EM_TX_TIMEOUT;
		EM_UNLOCK(adapter);
		return;
	}

	if (em_check_for_link(&adapter->hw))
		printf("em%d: watchdog timeout -- resetting\n", adapter->unit);

	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
	adapter->watchdog_events++;

	em_init_locked(adapter);
	EM_UNLOCK(adapter);
}

/*********************************************************************
 *  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.
 *
 *  return 0 on success, positive on failure
 **********************************************************************/

static void
em_init_locked(struct adapter * adapter)
{
	struct ifnet   *ifp;

	uint32_t	pba;
	ifp = adapter->ifp;

	INIT_DEBUGOUT("em_init: begin");

	mtx_assert(&adapter->mtx, MA_OWNED);

	em_stop(adapter);

	/*
	 * Packet Buffer Allocation (PBA)
	 * Writing PBA sets the receive portion of the buffer
	 * the remainder is used for the transmit buffer.
	 */
	switch (adapter->hw.mac_type) {
	case em_82547:
	case em_82547_rev_2: /* 82547: Total Packet Buffer is 40K */
		if (adapter->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 */
		adapter->tx_fifo_head = 0;
		adapter->tx_head_addr = pba << EM_TX_HEAD_ADDR_SHIFT;
		adapter->tx_fifo_size = (E1000_PBA_40K - pba) << EM_PBA_BYTES_SHIFT;
		break;
	case em_82571: /* 82571: Total Packet Buffer is 48K */
	case em_82572: /* 82572: Total Packet Buffer is 48K */
			pba = E1000_PBA_32K; /* 32K for Rx, 16K for Tx */
		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;
	default:
		/* Devices before 82547 had a Packet Buffer of 64K.   */
		if(adapter->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(&adapter->hw, PBA, pba);
	
	/* Get the latest mac address, User can use a LAA */
        bcopy(IF_LLADDR(adapter->ifp), adapter->hw.mac_addr,
              ETHER_ADDR_LEN);

	/* Initialize the hardware */
	if (em_hardware_init(adapter)) {
		printf("em%d: Unable to initialize the hardware\n", 
		       adapter->unit);
		return;
	}

	if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
		em_enable_vlans(adapter);

	/* Prepare transmit descriptors and buffers */
	if (em_setup_transmit_structures(adapter)) {
		printf("em%d: Could not setup transmit structures\n", 
		       adapter->unit);
		em_stop(adapter); 
		return;
	}
	em_initialize_transmit_unit(adapter);

	/* Setup Multicast table */
	em_set_multi(adapter);

	/* Prepare receive descriptors and buffers */
	if (em_setup_receive_structures(adapter)) {
		printf("em%d: Could not setup receive structures\n", 
		       adapter->unit);
		em_stop(adapter);
		return;
	}
	em_initialize_receive_unit(adapter);
 
	/* Don't loose promiscuous settings */
	em_set_promisc(adapter);

	ifp->if_drv_flags |= IFF_DRV_RUNNING;
	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;

	if (adapter->hw.mac_type >= em_82543) {
		if (ifp->if_capenable & IFCAP_TXCSUM)
			ifp->if_hwassist = EM_CHECKSUM_FEATURES;
		else
			ifp->if_hwassist = 0;
	}

	callout_reset(&adapter->timer, hz, em_local_timer, adapter);
	em_clear_hw_cntrs(&adapter->hw);
#ifdef DEVICE_POLLING
        /*
         * Only enable interrupts if we are not polling, make sure
         * they are off otherwise.
         */
        if (ifp->if_capenable & IFCAP_POLLING)
                em_disable_intr(adapter);
        else
#endif /* DEVICE_POLLING */
		em_enable_intr(adapter);

	/* Don't reset the phy next time init gets called */
	adapter->hw.phy_reset_disable = TRUE;
	
	return;
}

static void
em_init(void *arg)
{
	struct adapter * adapter = arg;

	EM_LOCK(adapter);
	em_init_locked(adapter);
	EM_UNLOCK(adapter);
	return;
}


#ifdef DEVICE_POLLING
static void     
em_poll_locked(struct ifnet *ifp, enum poll_cmd cmd, int count)
{
        struct adapter *adapter = ifp->if_softc;
        u_int32_t reg_icr;

	mtx_assert(&adapter->mtx, MA_OWNED);

        if (cmd == POLL_AND_CHECK_STATUS) {
                reg_icr = E1000_READ_REG(&adapter->hw, ICR);
                if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
			callout_stop(&adapter->timer);
                        adapter->hw.get_link_status = 1;
                        em_check_for_link(&adapter->hw);
                        em_print_link_status(adapter);
			callout_reset(&adapter->timer, hz, em_local_timer, adapter);
                }
        }
	em_process_receive_interrupts(adapter, count);
	em_clean_transmit_interrupts(adapter);
	
        if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd))
                em_start_locked(ifp);
}
        
static void     
em_poll(struct ifnet *ifp, enum poll_cmd cmd, int count)
{
        struct adapter *adapter = ifp->if_softc;

	EM_LOCK(adapter);
	if (ifp->if_drv_flags & IFF_DRV_RUNNING)
		em_poll_locked(ifp, cmd, count);
	EM_UNLOCK(adapter);
}
#endif /* DEVICE_POLLING */

#ifndef NO_EM_FASTINTR
static void
em_handle_link(void *context, int pending)
{
	struct adapter	*adapter = context;
	struct ifnet *ifp;

	ifp = adapter->ifp;

	EM_LOCK(adapter);

	callout_stop(&adapter->timer);
	adapter->hw.get_link_status = 1;
	em_check_for_link(&adapter->hw);
	em_print_link_status(adapter);
	callout_reset(&adapter->timer, hz, em_local_timer,
	    adapter);
	EM_UNLOCK(adapter);
}

static void
em_handle_rxtx(void *context, int pending)
{
	struct adapter	*adapter = context;
	struct ifnet	*ifp;

	ifp = adapter->ifp;

	/*
	 * TODO:
	 * It should be possible to run the tx clean loop without the lock.
	 */
	if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
		if (em_process_receive_interrupts(adapter,
		    adapter->rx_process_limit) != 0)
			taskqueue_enqueue(adapter->tq, &adapter->rxtx_task);
		EM_LOCK(adapter);
		em_clean_transmit_interrupts(adapter);

		if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd))
			em_start_locked(ifp);
		EM_UNLOCK(adapter);
	}

	em_enable_intr(adapter);
	return;
}
#endif

/*********************************************************************
 *
 *  Interrupt Service routine  
 *
 **********************************************************************/
#ifndef NO_EM_FASTINTR
static void
em_intr_fast(void *arg)
{
	struct adapter	*adapter = arg;
	struct ifnet	*ifp;
	uint32_t	reg_icr;

	ifp = adapter->ifp;  

#ifdef DEVICE_POLLING
	if (ifp->if_capenable & IFCAP_POLLING) {
		return;
	}
#endif /* DEVICE_POLLING */

	reg_icr = E1000_READ_REG(&adapter->hw, ICR);

	/* Hot eject?  */
	if (reg_icr == 0xffffffff)
		return;

	/* Definitely not our interrupt.  */
	if (reg_icr == 0x0)
		return;

	/*
	 * Starting with the 82571 chip, bit 31 should be used to
	 * determine whether the interrupt belongs to us.
	 */
	if (adapter->hw.mac_type >= em_82571 &&
	    (reg_icr & E1000_ICR_INT_ASSERTED) == 0)
		return;

	/*
	 * Mask interrupts until the taskqueue is finished running.  This is
	 * cheap, just assume that it is needed.  This also works around the
	 * MSI message reordering errata on certain systems.
	 */
	em_disable_intr(adapter);
	taskqueue_enqueue(adapter->tq, &adapter->rxtx_task);

	/* Link status change */
	if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC))
		taskqueue_enqueue(taskqueue_fast, &adapter->link_task);

	if (reg_icr & E1000_ICR_RXO) {
		adapter->rx_overruns++;
	}
	return;
}
#endif

static void
em_intr(void *arg)
{
	struct adapter	*adapter = arg;
	struct ifnet	*ifp;
	uint32_t	reg_icr;
	int		wantinit = 0;

	EM_LOCK(adapter);

	ifp = adapter->ifp;  

#ifdef DEVICE_POLLING
	if (ifp->if_capenable & IFCAP_POLLING) {
		EM_UNLOCK(adapter);
		return;
	}
#endif /* DEVICE_POLLING */

	for (;;) {
		reg_icr = E1000_READ_REG(&adapter->hw, ICR);
		if (adapter->hw.mac_type >= em_82571 &&
		    (reg_icr & E1000_ICR_INT_ASSERTED) == 0)
			break;
		else if (reg_icr == 0)
			break;

		/*
		 * XXX: some laptops trigger several spurious interrupts
		 * on em(4) when in the resume cycle. The ICR register
		 * reports all-ones value in this case. Processing such
		 * interrupts would lead to a freeze. I don't know why.
		 */
		if (reg_icr == 0xffffffff)
			break;

		if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
			em_process_receive_interrupts(adapter, -1);
			em_clean_transmit_interrupts(adapter);
		}
                 
		/* Link status change */
		if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
			callout_stop(&adapter->timer);
			adapter->hw.get_link_status = 1;
			em_check_for_link(&adapter->hw);
			em_print_link_status(adapter);
			callout_reset(&adapter->timer, hz, em_local_timer,
			    adapter);
		}

		if (reg_icr & E1000_ICR_RXO) {
			adapter->rx_overruns++;
			wantinit = 1;
		}
	}
#if 0
	if (wantinit)
		em_init_locked(adapter);
#endif
	if (ifp->if_drv_flags & IFF_DRV_RUNNING &&
	    !IFQ_DRV_IS_EMPTY(&ifp->if_snd))
		em_start_locked(ifp);

	EM_UNLOCK(adapter);
	return;
}



/*********************************************************************
 *
 *  Media Ioctl callback
 *
 *  This routine is called whenever the user queries the status of
 *  the interface using ifconfig.
 *
 **********************************************************************/
static void
em_media_status(struct ifnet *ifp, struct ifmediareq *ifmr)
{
	struct adapter * adapter = ifp->if_softc;

	INIT_DEBUGOUT("em_media_status: begin");

	em_check_for_link(&adapter->hw);
	if (E1000_READ_REG(&adapter->hw, STATUS) & E1000_STATUS_LU) {
		if (adapter->link_active == 0) {
			em_get_speed_and_duplex(&adapter->hw, 
						&adapter->link_speed, 
						&adapter->link_duplex);
			adapter->link_active = 1;
		}
	} else {
		if (adapter->link_active == 1) {
			adapter->link_speed = 0;
			adapter->link_duplex = 0;
			adapter->link_active = 0;
		}
	}

	ifmr->ifm_status = IFM_AVALID;
	ifmr->ifm_active = IFM_ETHER;

	if (!adapter->link_active)
		return;

	ifmr->ifm_status |= IFM_ACTIVE;

	if (adapter->hw.media_type == em_media_type_fiber) {
		ifmr->ifm_active |= IFM_1000_SX | IFM_FDX;
	} else {
		switch (adapter->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 (adapter->link_duplex == FULL_DUPLEX)
			ifmr->ifm_active |= IFM_FDX;
		else
			ifmr->ifm_active |= IFM_HDX;
	}
	return;
}

/*********************************************************************
 *
 *  Media Ioctl callback
 *
 *  This routine is called when the user changes speed/duplex using
 *  media/mediopt option with ifconfig.
 *
 **********************************************************************/
static int
em_media_change(struct ifnet *ifp)
{
	struct adapter * adapter = ifp->if_softc;
	struct ifmedia  *ifm = &adapter->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:
		adapter->hw.autoneg = DO_AUTO_NEG;
		adapter->hw.autoneg_advertised = AUTONEG_ADV_DEFAULT;
		break;
	case IFM_1000_SX:
	case IFM_1000_T:
		adapter->hw.autoneg = DO_AUTO_NEG;
		adapter->hw.autoneg_advertised = ADVERTISE_1000_FULL;
		break;
	case IFM_100_TX:
		adapter->hw.autoneg = FALSE;
		adapter->hw.autoneg_advertised = 0;
		if ((ifm->ifm_media & IFM_GMASK) == IFM_FDX)
			adapter->hw.forced_speed_duplex = em_100_full;
		else
			adapter->hw.forced_speed_duplex	= em_100_half;
		break;
	case IFM_10_T:
		adapter->hw.autoneg = FALSE;
		adapter->hw.autoneg_advertised = 0;
		if ((ifm->ifm_media & IFM_GMASK) == IFM_FDX)
			adapter->hw.forced_speed_duplex = em_10_full;
		else
			adapter->hw.forced_speed_duplex	= em_10_half;
		break;
	default:
		printf("em%d: Unsupported media type\n", adapter->unit);
	}

	/* As the speed/duplex settings my have changed we need to
	 * reset the PHY.
	 */
	adapter->hw.phy_reset_disable = FALSE;

	em_init(adapter);

	return(0);
}

/*********************************************************************
 *
 *  This routine maps the mbufs to tx descriptors.
 *
 *  return 0 on success, positive on failure
 **********************************************************************/
static int              
em_encap(struct adapter *adapter, struct mbuf **m_headp)
{
        u_int32_t       txd_upper;
        u_int32_t       txd_lower, txd_used = 0, txd_saved = 0;
        int             i, j, error = 0;
	bus_dmamap_t	map;

	struct mbuf	*m_head;

	/* For 82544 Workaround */
	DESC_ARRAY              desc_array;
	u_int32_t               array_elements;
	u_int32_t               counter;
        struct m_tag    *mtag;
	bus_dma_segment_t	segs[EM_MAX_SCATTER];
	int			nsegs;
        struct em_buffer   *tx_buffer;
        struct em_tx_desc *current_tx_desc = NULL;
        struct ifnet   *ifp = adapter->ifp;

	m_head = *m_headp;

        /*
         * Force a cleanup if number of TX descriptors
         * available hits the threshold
         */
        if (adapter->num_tx_desc_avail <= EM_TX_CLEANUP_THRESHOLD) {
                em_clean_transmit_interrupts(adapter);
                if (adapter->num_tx_desc_avail <= EM_TX_CLEANUP_THRESHOLD) {
                        adapter->no_tx_desc_avail1++;
                        return(ENOBUFS);
                }
        }

        /*
         * Map the packet for DMA.
         */
	tx_buffer = &adapter->tx_buffer_area[adapter->next_avail_tx_desc];
	error = bus_dmamap_load_mbuf_sg(adapter->txtag, tx_buffer->map, m_head,
	    segs, &nsegs, BUS_DMA_NOWAIT);
	map = tx_buffer->map;
        if (error != 0) {
                adapter->no_tx_dma_setup++;
                return (error);
        }
        KASSERT(nsegs != 0, ("em_encap: empty packet"));

        if (nsegs > adapter->num_tx_desc_avail) {
                adapter->no_tx_desc_avail2++;
		error = ENOBUFS;
		goto encap_fail;
        }


        if (ifp->if_hwassist > 0) {
                em_transmit_checksum_setup(adapter,  m_head,
                                           &txd_upper, &txd_lower);
        } else
                txd_upper = txd_lower = 0;


        /* Find out if we are in vlan mode */
        mtag = VLAN_OUTPUT_TAG(ifp, m_head);

	/*
	 * When operating in promiscuous mode, hardware encapsulation for
	 * packets is disabled.  This means we have to add the vlan
	 * encapsulation in the driver, since it will have come down from the
	 * VLAN layer with a tag instead of a VLAN header.
	 */
	if (mtag != NULL && adapter->em_insert_vlan_header) {
		struct ether_vlan_header *evl;
		struct ether_header eh;

		m_head = m_pullup(m_head, sizeof(eh));
		if (m_head == NULL) {
			*m_headp = NULL;
			error = ENOBUFS;
			goto encap_fail;
		}
		eh = *mtod(m_head, struct ether_header *);
		M_PREPEND(m_head, sizeof(*evl), M_DONTWAIT);
		if (m_head == NULL) {
			*m_headp = NULL;
			error = ENOBUFS;
			goto encap_fail;
		}
		m_head = m_pullup(m_head, sizeof(*evl));
		if (m_head == NULL) {
			*m_headp = NULL;
			error = ENOBUFS;
			goto encap_fail;
		}
		evl = mtod(m_head, struct ether_vlan_header *);
		bcopy(&eh, evl, sizeof(*evl));
		evl->evl_proto = evl->evl_encap_proto;
		evl->evl_encap_proto = htons(ETHERTYPE_VLAN);
		evl->evl_tag = htons(VLAN_TAG_VALUE(mtag));
		m_tag_delete(m_head, mtag);
		mtag = NULL;
		*m_headp = m_head;
	}

        i = adapter->next_avail_tx_desc;
	if (adapter->pcix_82544) {
		txd_saved = i;
		txd_used = 0;
	}
        for (j = 0; j < nsegs; j++) {
		/* If adapter is 82544 and on PCIX bus */
		if(adapter->pcix_82544) {
			/* 
			 * Check the Address and Length combination and 
			 * split the data accordingly 
			 */
                        array_elements = em_fill_descriptors(segs[j].ds_addr,
			    segs[j].ds_len, &desc_array);
			for (counter = 0; counter < array_elements; counter++) {
				if (txd_used == adapter->num_tx_desc_avail) {
					adapter->next_avail_tx_desc = txd_saved;
					adapter->no_tx_desc_avail2++;
					error = ENOBUFS;
					goto encap_fail;
                                }
                                tx_buffer = &adapter->tx_buffer_area[i];
                                current_tx_desc = &adapter->tx_desc_base[i];
                                current_tx_desc->buffer_addr = htole64(
					desc_array.descriptor[counter].address);
                                current_tx_desc->lower.data = htole32(
					(adapter->txd_cmd | txd_lower | 
					 (u_int16_t)desc_array.descriptor[counter].length));
                                current_tx_desc->upper.data = htole32((txd_upper));
                                if (++i == adapter->num_tx_desc)
                                         i = 0;

                                tx_buffer->m_head = NULL;
                                txd_used++;
                        }
		} else {
			tx_buffer = &adapter->tx_buffer_area[i];
			current_tx_desc = &adapter->tx_desc_base[i];

			current_tx_desc->buffer_addr = htole64(segs[j].ds_addr);
			current_tx_desc->lower.data = htole32(
				adapter->txd_cmd | txd_lower | segs[j].ds_len);
			current_tx_desc->upper.data = htole32(txd_upper);

			if (++i == adapter->num_tx_desc)
				i = 0;

			tx_buffer->m_head = NULL;
		}
        }

	adapter->next_avail_tx_desc = i;
	if (adapter->pcix_82544) {
		adapter->num_tx_desc_avail -= txd_used;
	}
	else {
		adapter->num_tx_desc_avail -= nsegs;
	}

        if (mtag != NULL) {
                /* Set the vlan id */
                current_tx_desc->upper.fields.special = htole16(VLAN_TAG_VALUE(mtag));

                /* Tell hardware to add tag */
                current_tx_desc->lower.data |= htole32(E1000_TXD_CMD_VLE);
        }

        tx_buffer->m_head = m_head;
        bus_dmamap_sync(adapter->txtag, map, BUS_DMASYNC_PREWRITE);

        /*
         * Last Descriptor of Packet needs End Of Packet (EOP)
         */
        current_tx_desc->lower.data |= htole32(E1000_TXD_CMD_EOP);

        /*
         * Advance the Transmit Descriptor Tail (Tdt), this tells the E1000
         * that this frame is available to transmit.
         */
        bus_dmamap_sync(adapter->txdma.dma_tag, adapter->txdma.dma_map,
            BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
        if (adapter->hw.mac_type == em_82547 &&
            adapter->link_duplex == HALF_DUPLEX) {
                em_82547_move_tail_locked(adapter);
        } else {
                E1000_WRITE_REG(&adapter->hw, TDT, i);
                if (adapter->hw.mac_type == em_82547) {
                        em_82547_update_fifo_head(adapter, m_head->m_pkthdr.len);
                }
        }

        return(0);

encap_fail:
	bus_dmamap_unload(adapter->txtag, tx_buffer->map);
	return (error);
}

/*********************************************************************
 *
 * 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.
 *
 **********************************************************************/
static void
em_82547_move_tail_locked(struct adapter *adapter)
{
	uint16_t hw_tdt;
	uint16_t sw_tdt;
	struct em_tx_desc *tx_desc;
	uint16_t length = 0;
	boolean_t eop = 0;

	EM_LOCK_ASSERT(adapter);

	hw_tdt = E1000_READ_REG(&adapter->hw, TDT);
	sw_tdt = adapter->next_avail_tx_desc;
	
	while (hw_tdt != sw_tdt) {
		tx_desc = &adapter->tx_desc_base[hw_tdt];
		length += tx_desc->lower.flags.length;
		eop = tx_desc->lower.data & E1000_TXD_CMD_EOP;
		if(++hw_tdt == adapter->num_tx_desc)
			hw_tdt = 0;

		if(eop) {
			if (em_82547_fifo_workaround(adapter, length)) {
				adapter->tx_fifo_wrk_cnt++;
				callout_reset(&adapter->tx_fifo_timer, 1,
					em_82547_move_tail, adapter);
				break;
			}
			E1000_WRITE_REG(&adapter->hw, TDT, hw_tdt);
			em_82547_update_fifo_head(adapter, length);
			length = 0;
		}
	}	
	return;
}

static void
em_82547_move_tail(void *arg)
{
        struct adapter *adapter = arg;

        EM_LOCK(adapter);
        em_82547_move_tail_locked(adapter);
        EM_UNLOCK(adapter);
}

static int
em_82547_fifo_workaround(struct adapter *adapter, int len)
{	
	int fifo_space, fifo_pkt_len;

	fifo_pkt_len = roundup2(len + EM_FIFO_HDR, EM_FIFO_HDR);

	if (adapter->link_duplex == HALF_DUPLEX) {
		fifo_space = adapter->tx_fifo_size - adapter->tx_fifo_head;

		if (fifo_pkt_len >= (EM_82547_PKT_THRESH + fifo_space)) {
			if (em_82547_tx_fifo_reset(adapter)) {
				return(0);
			}
			else {
				return(1);
			}
		}
	}

	return(0);
}

static void
em_82547_update_fifo_head(struct adapter *adapter, int len)
{
	int fifo_pkt_len = roundup2(len + EM_FIFO_HDR, EM_FIFO_HDR);
	
	/* tx_fifo_head is always 16 byte aligned */
	adapter->tx_fifo_head += fifo_pkt_len;
	if (adapter->tx_fifo_head >= adapter->tx_fifo_size) {
		adapter->tx_fifo_head -= adapter->tx_fifo_size;
	}

	return;
}


static int
em_82547_tx_fifo_reset(struct adapter *adapter)
{	
	uint32_t tctl;

	if ( (E1000_READ_REG(&adapter->hw, TDT) ==
	      E1000_READ_REG(&adapter->hw, TDH)) &&
	     (E1000_READ_REG(&adapter->hw, TDFT) == 
	      E1000_READ_REG(&adapter->hw, TDFH)) &&
	     (E1000_READ_REG(&adapter->hw, TDFTS) ==
	      E1000_READ_REG(&adapter->hw, TDFHS)) &&
	     (E1000_READ_REG(&adapter->hw, TDFPC) == 0)) {

		/* Disable TX unit */
		tctl = E1000_READ_REG(&adapter->hw, TCTL);
		E1000_WRITE_REG(&adapter->hw, TCTL, tctl & ~E1000_TCTL_EN);

		/* Reset FIFO pointers */
		E1000_WRITE_REG(&adapter->hw, TDFT,  adapter->tx_head_addr);
		E1000_WRITE_REG(&adapter->hw, TDFH,  adapter->tx_head_addr);
		E1000_WRITE_REG(&adapter->hw, TDFTS, adapter->tx_head_addr);
		E1000_WRITE_REG(&adapter->hw, TDFHS, adapter->tx_head_addr);

		/* Re-enable TX unit */
		E1000_WRITE_REG(&adapter->hw, TCTL, tctl);
		E1000_WRITE_FLUSH(&adapter->hw);

		adapter->tx_fifo_head = 0;
		adapter->tx_fifo_reset_cnt++;

		return(TRUE);
	}
	else {
		return(FALSE);
	}
}

static void
em_set_promisc(struct adapter * adapter)
{

	u_int32_t       reg_rctl;
	struct ifnet   *ifp = adapter->ifp;

	reg_rctl = E1000_READ_REG(&adapter->hw, RCTL);

	if (ifp->if_flags & IFF_PROMISC) {
		reg_rctl |= (E1000_RCTL_UPE | E1000_RCTL_MPE);
		E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);
		/* Disable VLAN stripping in promiscous mode 
		 * This enables bridging of vlan tagged frames to occur 
		 * and also allows vlan tags to be seen in tcpdump
		 */
		if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
			em_disable_vlans(adapter);
		adapter->em_insert_vlan_header = 1;
	} else if (ifp->if_flags & IFF_ALLMULTI) {
		reg_rctl |= E1000_RCTL_MPE;
		reg_rctl &= ~E1000_RCTL_UPE;
		E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);
		adapter->em_insert_vlan_header = 0;
	} else
		adapter->em_insert_vlan_header = 0;

	return;
}

static void
em_disable_promisc(struct adapter * adapter)
{
	u_int32_t       reg_rctl;
	struct ifnet   *ifp = adapter->ifp;

	reg_rctl = E1000_READ_REG(&adapter->hw, RCTL);

	reg_rctl &=  (~E1000_RCTL_UPE);
	reg_rctl &=  (~E1000_RCTL_MPE);
	E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);

	if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
		em_enable_vlans(adapter);
	adapter->em_insert_vlan_header = 0;

	return;
}


/*********************************************************************
 *  Multicast Update
 *
 *  This routine is called whenever multicast address list is updated.
 *
 **********************************************************************/

static void
em_set_multi(struct adapter * adapter)
{
        u_int32_t reg_rctl = 0;
        u_int8_t  mta[MAX_NUM_MULTICAST_ADDRESSES * ETH_LENGTH_OF_ADDRESS];
        struct ifmultiaddr  *ifma;
        int mcnt = 0;
        struct ifnet   *ifp = adapter->ifp;
    
        IOCTL_DEBUGOUT("em_set_multi: begin");
 
        if (adapter->hw.mac_type == em_82542_rev2_0) {
                reg_rctl = E1000_READ_REG(&adapter->hw, RCTL);
                if (adapter->hw.pci_cmd_word & CMD_MEM_WRT_INVALIDATE) { 
                        em_pci_clear_mwi(&adapter->hw);
                }
                reg_rctl |= E1000_RCTL_RST;
                E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);
                msec_delay(5);
        }

	IF_ADDR_LOCK(ifp);
        TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                if (ifma->ifma_addr->sa_family != AF_LINK)
                        continue;
 
		if (mcnt == MAX_NUM_MULTICAST_ADDRESSES) break;

                bcopy(LLADDR((struct sockaddr_dl *)ifma->ifma_addr),
                      &mta[mcnt*ETH_LENGTH_OF_ADDRESS], ETH_LENGTH_OF_ADDRESS);
                mcnt++;
        }
	IF_ADDR_UNLOCK(ifp);

        if (mcnt >= MAX_NUM_MULTICAST_ADDRESSES) {
                reg_rctl = E1000_READ_REG(&adapter->hw, RCTL);
                reg_rctl |= E1000_RCTL_MPE;
                E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);
        } else
                em_mc_addr_list_update(&adapter->hw, mta, mcnt, 0, 1);

        if (adapter->hw.mac_type == em_82542_rev2_0) {
                reg_rctl = E1000_READ_REG(&adapter->hw, RCTL);
                reg_rctl &= ~E1000_RCTL_RST;
                E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);
                msec_delay(5);
                if (adapter->hw.pci_cmd_word & CMD_MEM_WRT_INVALIDATE) {
                        em_pci_set_mwi(&adapter->hw);
                }
        }

        return;
}


/*********************************************************************
 *  Timer routine
 *
 *  This routine checks for link status and updates statistics.
 *
 **********************************************************************/

static void
em_local_timer(void *arg)
{
	struct ifnet   *ifp;
	struct adapter * adapter = arg;
	ifp = adapter->ifp;

	EM_LOCK(adapter);

	em_check_for_link(&adapter->hw);
	em_print_link_status(adapter);
	em_update_stats_counters(adapter);   
	if (em_display_debug_stats && ifp->if_drv_flags & IFF_DRV_RUNNING) {
		em_print_hw_stats(adapter);
	}
	em_smartspeed(adapter);

	callout_reset(&adapter->timer, hz, em_local_timer, adapter);

	EM_UNLOCK(adapter);
	return;
}

static void
em_print_link_status(struct adapter * adapter)
{
	struct ifnet *ifp = adapter->ifp;

	if (E1000_READ_REG(&adapter->hw, STATUS) & E1000_STATUS_LU) {
		if (adapter->link_active == 0) {
			em_get_speed_and_duplex(&adapter->hw, 
						&adapter->link_speed, 
						&adapter->link_duplex);
			if (bootverbose)
				printf("em%d: Link is up %d Mbps %s\n",
				       adapter->unit,
				       adapter->link_speed,
				       ((adapter->link_duplex == FULL_DUPLEX) ?
					"Full Duplex" : "Half Duplex"));
			adapter->link_active = 1;
			adapter->smartspeed = 0;
			if_link_state_change(ifp, LINK_STATE_UP);
		}
	} else {
		if (adapter->link_active == 1) {
			adapter->link_speed = 0;
			adapter->link_duplex = 0;
			if (bootverbose)
				printf("em%d: Link is Down\n", adapter->unit);
			adapter->link_active = 0;
			if_link_state_change(ifp, LINK_STATE_DOWN);
		}
	}

	return;
}

/*********************************************************************
 *
 *  This routine disables all traffic on the adapter by issuing a
 *  global reset on the MAC and deallocates TX/RX buffers. 
 *
 **********************************************************************/

static void
em_stop(void *arg)
{
	struct ifnet   *ifp;
	struct adapter * adapter = arg;
	ifp = adapter->ifp;

	mtx_assert(&adapter->mtx, MA_OWNED);

	INIT_DEBUGOUT("em_stop: begin");

	em_disable_intr(adapter);
	em_reset_hw(&adapter->hw);
	callout_stop(&adapter->timer);
	callout_stop(&adapter->tx_fifo_timer);
	em_free_transmit_structures(adapter);
	em_free_receive_structures(adapter);


	/* Tell the stack that the interface is no longer active */
	ifp->if_drv_flags &= ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE);

	return;
}


/*********************************************************************
 *
 *  Determine hardware revision.
 *
 **********************************************************************/
static void
em_identify_hardware(struct adapter * adapter)
{
	device_t dev = adapter->dev;

	/* Make sure our PCI config space has the necessary stuff set */
	adapter->hw.pci_cmd_word = pci_read_config(dev, PCIR_COMMAND, 2);
	if (!((adapter->hw.pci_cmd_word & PCIM_CMD_BUSMASTEREN) &&
	      (adapter->hw.pci_cmd_word & PCIM_CMD_MEMEN))) {
		printf("em%d: Memory Access and/or Bus Master bits were not set!\n", 
		       adapter->unit);
		adapter->hw.pci_cmd_word |= 
		(PCIM_CMD_BUSMASTEREN | PCIM_CMD_MEMEN);
		pci_write_config(dev, PCIR_COMMAND, adapter->hw.pci_cmd_word, 2);
	}

	/* Save off the information about this board */
	adapter->hw.vendor_id = pci_get_vendor(dev);
	adapter->hw.device_id = pci_get_device(dev);
	adapter->hw.revision_id = pci_read_config(dev, PCIR_REVID, 1);
	adapter->hw.subsystem_vendor_id = pci_read_config(dev, PCIR_SUBVEND_0, 2);
	adapter->hw.subsystem_id = pci_read_config(dev, PCIR_SUBDEV_0, 2);

	/* Identify the MAC */
        if (em_set_mac_type(&adapter->hw))
                printf("em%d: Unknown MAC Type\n", adapter->unit);
	
	if(adapter->hw.mac_type == em_82541 || 
	   adapter->hw.mac_type == em_82541_rev_2 ||
	   adapter->hw.mac_type == em_82547 || 
	   adapter->hw.mac_type == em_82547_rev_2)
		adapter->hw.phy_init_script = TRUE;

        return;
}

static int
em_allocate_pci_resources(struct adapter * adapter)
{
	int             val, rid;
	device_t        dev = adapter->dev;

	rid = PCIR_BAR(0);
	adapter->res_memory = bus_alloc_resource_any(dev, SYS_RES_MEMORY,
						     &rid, RF_ACTIVE);
	if (!(adapter->res_memory)) {
		printf("em%d: Unable to allocate bus resource: memory\n", 
		       adapter->unit);
		return(ENXIO);
	}
	adapter->osdep.mem_bus_space_tag = 
	rman_get_bustag(adapter->res_memory);
	adapter->osdep.mem_bus_space_handle = 
	rman_get_bushandle(adapter->res_memory);
	adapter->hw.hw_addr = (uint8_t *)&adapter->osdep.mem_bus_space_handle;


	if (adapter->hw.mac_type > em_82543) {
		/* Figure our where our IO BAR is ? */
		for (rid = PCIR_BAR(0); rid < PCIR_CIS;) {
			val = pci_read_config(dev, rid, 4);
			if (E1000_BAR_TYPE(val) == E1000_BAR_TYPE_IO) {
				adapter->io_rid = rid;
				break;
			}
			rid += 4;
			/* check for 64bit BAR */
			if (E1000_BAR_MEM_TYPE(val) == E1000_BAR_MEM_TYPE_64BIT)
				rid += 4;
		}
		if (rid >= PCIR_CIS) {
			printf("em%d: Unable to locate IO BAR\n", adapter->unit);
			return (ENXIO);
		}
		adapter->res_ioport = bus_alloc_resource_any(dev, 
							     SYS_RES_IOPORT,
							     &adapter->io_rid,
							     RF_ACTIVE);
		if (!(adapter->res_ioport)) {
			printf("em%d: Unable to allocate bus resource: ioport\n",
			       adapter->unit);
			return(ENXIO);  
		}
		adapter->hw.io_base = 0;
		adapter->osdep.io_bus_space_tag =
		    rman_get_bustag(adapter->res_ioport);
		adapter->osdep.io_bus_space_handle =
		    rman_get_bushandle(adapter->res_ioport);
	}

	rid = 0x0;
	adapter->res_interrupt = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
						        RF_SHAREABLE | 
							RF_ACTIVE);
	if (!(adapter->res_interrupt)) {
		printf("em%d: Unable to allocate bus resource: interrupt\n", 
		       adapter->unit);
		return(ENXIO);
	}

	/*
	 * XXX The interrupt shouldn't be set up until the driver and the
	 * chip is more initialized.
	 */
	em_disable_intr(adapter);

	/*
	 * Try allocating a fast interrupt and the associated deferred
	 * processing contexts.  If that doesn't work, try just using an
	 * ithread.
	 */
#ifndef NO_EM_FASTINTR
	if (bus_setup_intr(dev, adapter->res_interrupt,
			   INTR_TYPE_NET | INTR_FAST, em_intr_fast, adapter,
			   &adapter->int_handler_tag) == 0) {

		/* Init the deferred processing contexts. */
		TASK_INIT(&adapter->rxtx_task, 0, em_handle_rxtx, adapter);
		TASK_INIT(&adapter->link_task, 0, em_handle_link, adapter);
		adapter->tq = taskqueue_create_fast("em_taskq", M_NOWAIT,
			taskqueue_thread_enqueue,
			&adapter->tq, &adapter->tqproc);
		kthread_create(taskqueue_thread_loop,
			&adapter->tq, &adapter->tqproc,
			0, 0, "%s taskq", device_get_nameunit(adapter->dev));
		mtx_lock_spin(&sched_lock);
		sched_prio(FIRST_THREAD_IN_PROC(adapter->tqproc), PI_NET);
		mtx_unlock_spin(&sched_lock);
	}
#endif
	if (adapter->int_handler_tag == NULL) {
		if (bus_setup_intr(dev, adapter->res_interrupt,
				   INTR_TYPE_NET | INTR_MPSAFE,
				   em_intr, adapter,
				   &adapter->int_handler_tag)) {
			printf("em%d: Error registering interrupt handler!\n", 
			       adapter->unit);
			return(ENXIO);
		}
	}

	adapter->hw.back = &adapter->osdep;
	em_enable_intr(adapter);

	return(0);
}

static void
em_free_pci_resources(struct adapter * adapter)
{
	device_t dev = adapter->dev;

	if (adapter->tq != NULL) {
		taskqueue_free(adapter->tq);
	}
	if (adapter->res_interrupt != NULL) {
		bus_teardown_intr(dev, adapter->res_interrupt, 
				  adapter->int_handler_tag);
		bus_release_resource(dev, SYS_RES_IRQ, 0, 
				     adapter->res_interrupt);
	}
	if (adapter->res_memory != NULL) {
		bus_release_resource(dev, SYS_RES_MEMORY, PCIR_BAR(0), 
				     adapter->res_memory);
	}

	if (adapter->res_ioport != NULL) {
		bus_release_resource(dev, SYS_RES_IOPORT, adapter->io_rid, 
				     adapter->res_ioport);
	}
	return;
}

/*********************************************************************
 *
 *  Initialize the hardware to a configuration as specified by the
 *  adapter structure. The controller is reset, the EEPROM is
 *  verified, the MAC address is set, then the shared initialization
 *  routines are called.
 *
 **********************************************************************/
static int
em_hardware_init(struct adapter * adapter)
{
	uint16_t rx_buffer_size;

        INIT_DEBUGOUT("em_hardware_init: begin");
	/* Issue a global reset */
	em_reset_hw(&adapter->hw);

	/* When hardware is reset, fifo_head is also reset */
	adapter->tx_fifo_head = 0;

	/* Make sure we have a good EEPROM before we read from it */
	if (em_validate_eeprom_checksum(&adapter->hw) < 0) {
		printf("em%d: The EEPROM Checksum Is Not Valid\n",
		       adapter->unit);
		return(EIO);
	}

	if (em_read_part_num(&adapter->hw, &(adapter->part_num)) < 0) {
		printf("em%d: EEPROM read error while reading part number\n",
		       adapter->unit);
		return(EIO);
	}

	/*
	 * 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(&adapter->hw, PBA) & 0xffff) << 10 );

	adapter->hw.fc_high_water = rx_buffer_size -
	    roundup2(adapter->hw.max_frame_size, 1024);
	adapter->hw.fc_low_water = adapter->hw.fc_high_water - 1500;
	adapter->hw.fc_pause_time = 0x1000;
	adapter->hw.fc_send_xon = TRUE;
	adapter->hw.fc = em_fc_full;

	if (em_init_hw(&adapter->hw) < 0) {
		printf("em%d: Hardware Initialization Failed",
		       adapter->unit);
		return(EIO);
	}

	em_check_for_link(&adapter->hw);
	if (E1000_READ_REG(&adapter->hw, STATUS) & E1000_STATUS_LU)
		adapter->link_active = 1;
	else
		adapter->link_active = 0;

	if (adapter->link_active) {
		em_get_speed_and_duplex(&adapter->hw, 
					&adapter->link_speed, 
					&adapter->link_duplex);
	} else {
		adapter->link_speed = 0;
		adapter->link_duplex = 0;
	}

	return(0);
}

/*********************************************************************
 *
 *  Setup networking device structure and register an interface.
 *
 **********************************************************************/
static void
em_setup_interface(device_t dev, struct adapter * adapter)
{
	struct ifnet   *ifp;
	INIT_DEBUGOUT("em_setup_interface: begin");

	ifp = adapter->ifp = if_alloc(IFT_ETHER);
	if (ifp == NULL)
		panic("%s: can not if_alloc()", device_get_nameunit(dev));
	if_initname(ifp, device_get_name(dev), device_get_unit(dev));
	ifp->if_mtu = ETHERMTU;
	ifp->if_baudrate = 1000000000;
	ifp->if_init =  em_init;
	ifp->if_softc = adapter;
	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
	ifp->if_ioctl = em_ioctl;
	ifp->if_start = em_start;
	ifp->if_watchdog = em_watchdog;
	IFQ_SET_MAXLEN(&ifp->if_snd, adapter->num_tx_desc - 1);
	ifp->if_snd.ifq_drv_maxlen = adapter->num_tx_desc - 1;
	IFQ_SET_READY(&ifp->if_snd);

        ether_ifattach(ifp, adapter->hw.mac_addr);

	ifp->if_capabilities = ifp->if_capenable = 0;

	if (adapter->hw.mac_type >= em_82543) {
		ifp->if_capabilities |= IFCAP_HWCSUM;
		ifp->if_capenable |= IFCAP_HWCSUM;
	}

	/*
	 * Tell the upper layer(s) we support long frames.
	 */
	ifp->if_data.ifi_hdrlen = sizeof(struct ether_vlan_header);
	ifp->if_capabilities |= IFCAP_VLAN_HWTAGGING | IFCAP_VLAN_MTU;
	ifp->if_capenable |= IFCAP_VLAN_MTU;

#ifdef DEVICE_POLLING
	ifp->if_capabilities |= IFCAP_POLLING;
#endif

	/* 
	 * Specify the media types supported by this adapter and register
	 * callbacks to update media and link information
	 */
	ifmedia_init(&adapter->media, IFM_IMASK, em_media_change,
		     em_media_status);
	if (adapter->hw.media_type == em_media_type_fiber) {
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_1000_SX | IFM_FDX, 
			    0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_1000_SX, 
			    0, NULL);
	} else {
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_10_T, 0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_10_T | IFM_FDX, 
			    0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_100_TX, 
			    0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_100_TX | IFM_FDX, 
			    0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_1000_T | IFM_FDX, 
			    0, NULL);
		ifmedia_add(&adapter->media, IFM_ETHER | IFM_1000_T, 0, NULL);
	}
	ifmedia_add(&adapter->media, IFM_ETHER | IFM_AUTO, 0, NULL);
	ifmedia_set(&adapter->media, IFM_ETHER | IFM_AUTO);

	return;
}


/*********************************************************************
 *
 *  Workaround for SmartSpeed on 82541 and 82547 controllers
 *
 **********************************************************************/        
static void
em_smartspeed(struct adapter *adapter)
{
        uint16_t phy_tmp;
 
	if(adapter->link_active || (adapter->hw.phy_type != em_phy_igp) || 
	   !adapter->hw.autoneg || !(adapter->hw.autoneg_advertised & ADVERTISE_1000_FULL))
		return;

        if(adapter->smartspeed == 0) {
                /* If Master/Slave config fault is asserted twice,
                 * we assume back-to-back */
                em_read_phy_reg(&adapter->hw, PHY_1000T_STATUS, &phy_tmp);
                if(!(phy_tmp & SR_1000T_MS_CONFIG_FAULT)) return;
                em_read_phy_reg(&adapter->hw, PHY_1000T_STATUS, &phy_tmp);
                if(phy_tmp & SR_1000T_MS_CONFIG_FAULT) {
                        em_read_phy_reg(&adapter->hw, PHY_1000T_CTRL,
					&phy_tmp);
                        if(phy_tmp & CR_1000T_MS_ENABLE) {
                                phy_tmp &= ~CR_1000T_MS_ENABLE;
                                em_write_phy_reg(&adapter->hw,
                                                    PHY_1000T_CTRL, phy_tmp);
                                adapter->smartspeed++;
                                if(adapter->hw.autoneg &&
                                   !em_phy_setup_autoneg(&adapter->hw) &&
				   !em_read_phy_reg(&adapter->hw, PHY_CTRL,
                                                       &phy_tmp)) {
                                        phy_tmp |= (MII_CR_AUTO_NEG_EN |  
                                                    MII_CR_RESTART_AUTO_NEG);
                                        em_write_phy_reg(&adapter->hw,
							 PHY_CTRL, phy_tmp);
                                }
                        }
                }
                return;
        } else if(adapter->smartspeed == EM_SMARTSPEED_DOWNSHIFT) {
                /* If still no link, perhaps using 2/3 pair cable */
                em_read_phy_reg(&adapter->hw, PHY_1000T_CTRL, &phy_tmp);
                phy_tmp |= CR_1000T_MS_ENABLE;
                em_write_phy_reg(&adapter->hw, PHY_1000T_CTRL, phy_tmp);
                if(adapter->hw.autoneg &&
                   !em_phy_setup_autoneg(&adapter->hw) &&
                   !em_read_phy_reg(&adapter->hw, PHY_CTRL, &phy_tmp)) {
                        phy_tmp |= (MII_CR_AUTO_NEG_EN |
                                    MII_CR_RESTART_AUTO_NEG);
                        em_write_phy_reg(&adapter->hw, PHY_CTRL, phy_tmp);
                }
        }
        /* Restart process after EM_SMARTSPEED_MAX iterations */
        if(adapter->smartspeed++ == EM_SMARTSPEED_MAX)
                adapter->smartspeed = 0;

	return;
}


/*
 * Manage DMA'able memory.
 */
static void
em_dmamap_cb(void *arg, bus_dma_segment_t *segs, int nseg, int error)
{ 
        if (error)
                return;
        *(bus_addr_t *) arg = segs[0].ds_addr;
}

static int
em_dma_malloc(struct adapter *adapter, bus_size_t size,
        struct em_dma_alloc *dma, int mapflags)
{
        int r;
         
	r = bus_dma_tag_create(NULL,                    /* parent */
                               E1000_DBA_ALIGN, 0,      /* alignment, bounds */
                               BUS_SPACE_MAXADDR,       /* lowaddr */
                               BUS_SPACE_MAXADDR,       /* highaddr */
                               NULL, NULL,              /* filter, filterarg */
                               size,                    /* maxsize */
                               1,                       /* nsegments */
                               size,                    /* maxsegsize */
                               BUS_DMA_ALLOCNOW,        /* flags */
			       NULL,			/* lockfunc */
			       NULL,			/* lockarg */
                               &dma->dma_tag);
        if (r != 0) {
                printf("em%d: em_dma_malloc: bus_dma_tag_create failed; "
                        "error %u\n", adapter->unit, r);
                goto fail_0;
        }

        r = bus_dmamem_alloc(dma->dma_tag, (void**) &dma->dma_vaddr,
                             BUS_DMA_NOWAIT, &dma->dma_map);
        if (r != 0) {
                printf("em%d: em_dma_malloc: bus_dmammem_alloc failed; "
                        "size %ju, error %d\n", adapter->unit,
			(uintmax_t)size, r);
                goto fail_2;
        }

	dma->dma_paddr = 0;
        r = bus_dmamap_load(dma->dma_tag, dma->dma_map, dma->dma_vaddr,
                            size,
                            em_dmamap_cb,
                            &dma->dma_paddr,
                            mapflags | BUS_DMA_NOWAIT);
        if (r != 0 || dma->dma_paddr == 0) {
                printf("em%d: em_dma_malloc: bus_dmamap_load failed; "
                        "error %u\n", adapter->unit, r);
                goto fail_3;
        }

        return (0);

fail_3:
        bus_dmamap_unload(dma->dma_tag, dma->dma_map);
fail_2:
        bus_dmamem_free(dma->dma_tag, dma->dma_vaddr, dma->dma_map);
        bus_dma_tag_destroy(dma->dma_tag);
fail_0:
        dma->dma_map = NULL;
        dma->dma_tag = NULL;
        return (r);
}

static void
em_dma_free(struct adapter *adapter, struct em_dma_alloc *dma)
{
	if (dma->dma_tag == NULL)
		return;
	if (dma->dma_map != NULL) {
		bus_dmamap_sync(dma->dma_tag, dma->dma_map,
		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
		bus_dmamap_unload(dma->dma_tag, dma->dma_map);
		bus_dmamem_free(dma->dma_tag, dma->dma_vaddr, dma->dma_map);
		dma->dma_map = NULL;
	}
        bus_dma_tag_destroy(dma->dma_tag);
	dma->dma_tag = NULL;
}


/*********************************************************************
 *
 *  Allocate memory for tx_buffer structures. The tx_buffer stores all 
 *  the information needed to transmit a packet on the wire. 
 *
 **********************************************************************/
static int
em_allocate_transmit_structures(struct adapter * adapter)
{
	if (!(adapter->tx_buffer_area =
	      (struct em_buffer *) malloc(sizeof(struct em_buffer) *
					     adapter->num_tx_desc, M_DEVBUF,
					     M_NOWAIT))) {
		printf("em%d: Unable to allocate tx_buffer memory\n", 
		       adapter->unit);
		return ENOMEM;
	}

	bzero(adapter->tx_buffer_area,
	      sizeof(struct em_buffer) * adapter->num_tx_desc);

	return 0;
}

/*********************************************************************
 *
 *  Allocate and initialize transmit structures. 
 *
 **********************************************************************/
static int
em_setup_transmit_structures(struct adapter * adapter)
{
	struct em_buffer *tx_buffer;
	bus_size_t size;
	int error, i;

        /*
         * Setup DMA descriptor areas.
         */
	size = roundup2(adapter->hw.max_frame_size, MCLBYTES);
	if ((error = bus_dma_tag_create(NULL,           /* parent */
                               1, 0,                    /* alignment, bounds */
                               BUS_SPACE_MAXADDR,       /* lowaddr */ 
                               BUS_SPACE_MAXADDR,       /* highaddr */
                               NULL, NULL,              /* filter, filterarg */
                               size,                    /* maxsize */
                               EM_MAX_SCATTER,          /* nsegments */
                               size,                    /* maxsegsize */
                               0,                       /* flags */ 
			       NULL,			/* lockfunc */
			       NULL,			/* lockarg */
                               &adapter->txtag)) != 0) {
		printf("em%d: Unable to allocate TX DMA tag\n", adapter->unit);
		goto fail;
        }

        if ((error = em_allocate_transmit_structures(adapter)) != 0)
		goto fail;

        bzero((void *) adapter->tx_desc_base,
              (sizeof(struct em_tx_desc)) * adapter->num_tx_desc);
	tx_buffer = adapter->tx_buffer_area;
	for (i = 0; i < adapter->num_tx_desc; i++) {
		error = bus_dmamap_create(adapter->txtag, 0, &tx_buffer->map);
		if (error != 0) {
			printf("em%d: Unable to create TX DMA map\n",
			    adapter->unit);
			goto fail;
		}
		tx_buffer++;
	}

        adapter->next_avail_tx_desc = 0;
        adapter->oldest_used_tx_desc = 0;

        /* Set number of descriptors available */
        adapter->num_tx_desc_avail = adapter->num_tx_desc;

        /* Set checksum context */
        adapter->active_checksum_context = OFFLOAD_NONE;
	bus_dmamap_sync(adapter->txdma.dma_tag, adapter->txdma.dma_map,
	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

        return (0);

fail:
	em_free_transmit_structures(adapter);
	return (error);
}

/*********************************************************************
 *
 *  Enable transmit unit.
 *
 **********************************************************************/
static void
em_initialize_transmit_unit(struct adapter * adapter)
{
	u_int32_t       reg_tctl;
	u_int32_t       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 = adapter->txdma.dma_paddr;
	E1000_WRITE_REG(&adapter->hw, TDBAL, (u_int32_t)bus_addr);
	E1000_WRITE_REG(&adapter->hw, TDBAH, (u_int32_t)(bus_addr >> 32));
	E1000_WRITE_REG(&adapter->hw, TDLEN, 
			adapter->num_tx_desc *
			sizeof(struct em_tx_desc));

	/* Setup the HW Tx Head and Tail descriptor pointers */
	E1000_WRITE_REG(&adapter->hw, TDH, 0);
	E1000_WRITE_REG(&adapter->hw, TDT, 0);


	HW_DEBUGOUT2("Base = %x, Length = %x\n", 
		     E1000_READ_REG(&adapter->hw, TDBAL),
		     E1000_READ_REG(&adapter->hw, TDLEN));

	/* Set the default values for the Tx Inter Packet Gap timer */
	switch (adapter->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;
        default:
                if (adapter->hw.media_type == em_media_type_fiber)
                        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(&adapter->hw, TIPG, reg_tipg);
	E1000_WRITE_REG(&adapter->hw, TIDV, adapter->tx_int_delay.value);
	if(adapter->hw.mac_type >= em_82540)
		E1000_WRITE_REG(&adapter->hw, TADV,
		    adapter->tx_abs_int_delay.value);

	/* Program the Transmit Control Register */
	reg_tctl = E1000_TCTL_PSP | E1000_TCTL_EN |
		   (E1000_COLLISION_THRESHOLD << E1000_CT_SHIFT);
	if (adapter->hw.mac_type >= em_82571)
		reg_tctl |= E1000_TCTL_MULR;
	if (adapter->link_duplex == 1) {
		reg_tctl |= E1000_FDX_COLLISION_DISTANCE << E1000_COLD_SHIFT;
	} else {
		reg_tctl |= E1000_HDX_COLLISION_DISTANCE << E1000_COLD_SHIFT;
	}
	E1000_WRITE_REG(&adapter->hw, TCTL, reg_tctl);

	/* Setup Transmit Descriptor Settings for this adapter */   
	adapter->txd_cmd = E1000_TXD_CMD_IFCS | E1000_TXD_CMD_RS;

	if (adapter->tx_int_delay.value > 0)
		adapter->txd_cmd |= E1000_TXD_CMD_IDE;

	return;
}

/*********************************************************************
 *
 *  Free all transmit related data structures.
 *
 **********************************************************************/
static void
em_free_transmit_structures(struct adapter * adapter)
{
        struct em_buffer   *tx_buffer;
        int             i;

        INIT_DEBUGOUT("free_transmit_structures: begin");

        if (adapter->tx_buffer_area != NULL) {
                tx_buffer = adapter->tx_buffer_area;
                for (i = 0; i < adapter->num_tx_desc; i++, tx_buffer++) {
                        if (tx_buffer->m_head != NULL) {
				bus_dmamap_sync(adapter->txtag, tx_buffer->map,
				    BUS_DMASYNC_POSTWRITE);
				bus_dmamap_unload(adapter->txtag,
				    tx_buffer->map);
                                m_freem(tx_buffer->m_head);
				tx_buffer->m_head = NULL;
                        } else if (tx_buffer->map != NULL)
				bus_dmamap_unload(adapter->txtag,
				    tx_buffer->map);
			if (tx_buffer->map != NULL) {
				bus_dmamap_destroy(adapter->txtag,
				    tx_buffer->map);
				tx_buffer->map = NULL;
			}
                }
        }
        if (adapter->tx_buffer_area != NULL) {
                free(adapter->tx_buffer_area, M_DEVBUF);
                adapter->tx_buffer_area = NULL;
        }
        if (adapter->txtag != NULL) {
                bus_dma_tag_destroy(adapter->txtag);
                adapter->txtag = NULL;
        }
        return;
}

/*********************************************************************
 *
 *  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.
 *
 **********************************************************************/
static void
em_transmit_checksum_setup(struct adapter * adapter,
			   struct mbuf *mp,
			   u_int32_t *txd_upper,
			   u_int32_t *txd_lower) 
{
	struct em_context_desc *TXD;
	struct em_buffer *tx_buffer;
	int curr_txd;

	if (mp->m_pkthdr.csum_flags) {

		if (mp->m_pkthdr.csum_flags & CSUM_TCP) {
			*txd_upper = E1000_TXD_POPTS_TXSM << 8;
			*txd_lower = E1000_TXD_CMD_DEXT | E1000_TXD_DTYP_D;
			if (adapter->active_checksum_context == OFFLOAD_TCP_IP)
				return;
			else
				adapter->active_checksum_context = OFFLOAD_TCP_IP;

		} else if (mp->m_pkthdr.csum_flags & CSUM_UDP) {
			*txd_upper = E1000_TXD_POPTS_TXSM << 8;
			*txd_lower = E1000_TXD_CMD_DEXT | E1000_TXD_DTYP_D;
			if (adapter->active_checksum_context == OFFLOAD_UDP_IP)
				return;
			else
				adapter->active_checksum_context = OFFLOAD_UDP_IP;
		} else {
			*txd_upper = 0;
			*txd_lower = 0;
			return;
		}
	} else {
		*txd_upper = 0;
		*txd_lower = 0;
		return;
	}

	/* If we reach this point, the checksum offload context
	 * needs to be reset.
	 */
	curr_txd = adapter->next_avail_tx_desc;
	tx_buffer = &adapter->tx_buffer_area[curr_txd];
	TXD = (struct em_context_desc *) &adapter->tx_desc_base[curr_txd];

	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 (adapter->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 (adapter->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(adapter->txd_cmd | E1000_TXD_CMD_DEXT);

	tx_buffer->m_head = NULL;

	if (++curr_txd == adapter->num_tx_desc)
		curr_txd = 0;

	adapter->num_tx_desc_avail--;
	adapter->next_avail_tx_desc = curr_txd;

	return;
}

/**********************************************************************
 *
 *  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.
 *
 **********************************************************************/
static void
em_clean_transmit_interrupts(struct adapter * adapter)
{
        int i, num_avail;
        struct em_buffer *tx_buffer;
        struct em_tx_desc   *tx_desc;
	struct ifnet   *ifp = adapter->ifp;

	mtx_assert(&adapter->mtx, MA_OWNED);

        if (adapter->num_tx_desc_avail == adapter->num_tx_desc)
                return;

        num_avail = adapter->num_tx_desc_avail;
        i = adapter->oldest_used_tx_desc;

        tx_buffer = &adapter->tx_buffer_area[i];
        tx_desc = &adapter->tx_desc_base[i];

        bus_dmamap_sync(adapter->txdma.dma_tag, adapter->txdma.dma_map,
            BUS_DMASYNC_POSTREAD);
        while (tx_desc->upper.fields.status & E1000_TXD_STAT_DD) {

                tx_desc->upper.data = 0;
                num_avail++;

                if (tx_buffer->m_head) {
			ifp->if_opackets++;
			bus_dmamap_sync(adapter->txtag, tx_buffer->map,
			    BUS_DMASYNC_POSTWRITE);
			bus_dmamap_unload(adapter->txtag, tx_buffer->map);

                        m_freem(tx_buffer->m_head);
                        tx_buffer->m_head = NULL;
                }

                if (++i == adapter->num_tx_desc)
                        i = 0;

                tx_buffer = &adapter->tx_buffer_area[i];
                tx_desc = &adapter->tx_desc_base[i];
        }
        bus_dmamap_sync(adapter->txdma.dma_tag, adapter->txdma.dma_map,
            BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

        adapter->oldest_used_tx_desc = i;

        /*
         * If we have enough room, clear IFF_DRV_OACTIVE to tell the stack
         * that it is OK to send packets.
         * If there are no pending descriptors, clear the timeout. Otherwise,
         * if some descriptors have been freed, restart the timeout.
         */
        if (num_avail > EM_TX_CLEANUP_THRESHOLD) {                
                ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
                if (num_avail == adapter->num_tx_desc)
                        ifp->if_timer = 0;
                else if (num_avail == adapter->num_tx_desc_avail)
                        ifp->if_timer = EM_TX_TIMEOUT;
        }
        adapter->num_tx_desc_avail = num_avail;
        return;
}

/*********************************************************************
 *
 *  Get a buffer from system mbuf buffer pool.
 *
 **********************************************************************/
static int
em_get_buf(int i, struct adapter *adapter,
           struct mbuf *nmp)
{
        struct mbuf    *mp = nmp;
        struct em_buffer *rx_buffer;
        struct ifnet   *ifp;
	bus_dma_segment_t segs[1];
	int error, nsegs;

        ifp = adapter->ifp;

        if (mp == NULL) {
                mp = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
                if (mp == NULL) {
                        adapter->mbuf_cluster_failed++;
                        return(ENOBUFS);
                }
                mp->m_len = mp->m_pkthdr.len = MCLBYTES;
        } else {
                mp->m_len = mp->m_pkthdr.len = MCLBYTES;
                mp->m_data = mp->m_ext.ext_buf;
                mp->m_next = NULL;
        }

        if (ifp->if_mtu <= ETHERMTU) {
                m_adj(mp, ETHER_ALIGN);
        }

        rx_buffer = &adapter->rx_buffer_area[i];

        /*
         * Using memory from the mbuf cluster pool, invoke the
         * bus_dma machinery to arrange the memory mapping.
         */
        error = bus_dmamap_load_mbuf_sg(adapter->rxtag, rx_buffer->map,
	    mp, segs, &nsegs, 0);
        if (error != 0) {
                m_free(mp);
                return(error);
        }
	/* If nsegs is wrong then the stack is corrupt */
	KASSERT(nsegs == 1, ("Too many segments returned!"));
        rx_buffer->m_head = mp;
        adapter->rx_desc_base[i].buffer_addr = htole64(segs[0].ds_addr);
        bus_dmamap_sync(adapter->rxtag, rx_buffer->map, BUS_DMASYNC_PREREAD);

        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.
 *
 **********************************************************************/
static int
em_allocate_receive_structures(struct adapter * adapter)
{
        int             i, error;
        struct em_buffer *rx_buffer;

        if (!(adapter->rx_buffer_area =
              (struct em_buffer *) malloc(sizeof(struct em_buffer) *
                                          adapter->num_rx_desc, M_DEVBUF,
                                          M_NOWAIT))) {
                printf("em%d: Unable to allocate rx_buffer memory\n",
                       adapter->unit);
                return(ENOMEM);
        }

        bzero(adapter->rx_buffer_area,
              sizeof(struct em_buffer) * adapter->num_rx_desc);

        error = bus_dma_tag_create(NULL,                /* parent */
                               1, 0,                    /* alignment, bounds */
                               BUS_SPACE_MAXADDR,       /* lowaddr */
                               BUS_SPACE_MAXADDR,       /* highaddr */
                               NULL, NULL,              /* filter, filterarg */
                               MCLBYTES,                /* maxsize */
                               1,                       /* nsegments */
                               MCLBYTES,                /* maxsegsize */
                               BUS_DMA_ALLOCNOW,        /* flags */
			       NULL,			/* lockfunc */
			       NULL,			/* lockarg */
                               &adapter->rxtag);
        if (error != 0) {
                printf("em%d: em_allocate_receive_structures: "
                        "bus_dma_tag_create failed; error %u\n",
                       adapter->unit, error);
                goto fail;
        }

        rx_buffer = adapter->rx_buffer_area;
        for (i = 0; i < adapter->num_rx_desc; i++, rx_buffer++) {
                error = bus_dmamap_create(adapter->rxtag, BUS_DMA_NOWAIT,
                                          &rx_buffer->map);
                if (error != 0) {
                        printf("em%d: em_allocate_receive_structures: "
                                "bus_dmamap_create failed; error %u\n",
                                adapter->unit, error);
                        goto fail;
                }
        }

        for (i = 0; i < adapter->num_rx_desc; i++) {
                error = em_get_buf(i, adapter, NULL);
		if (error != 0)
			goto fail;
        }
        bus_dmamap_sync(adapter->rxdma.dma_tag, adapter->rxdma.dma_map,
            BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

        return(0);

fail:
	em_free_receive_structures(adapter);
        return (error);
}

/*********************************************************************
 *
 *  Allocate and initialize receive structures.
 *  
 **********************************************************************/
static int
em_setup_receive_structures(struct adapter * adapter)
{
	bzero((void *) adapter->rx_desc_base,
              (sizeof(struct em_rx_desc)) * adapter->num_rx_desc);

	if (em_allocate_receive_structures(adapter))
		return ENOMEM;

	/* Setup our descriptor pointers */
        adapter->next_rx_desc_to_check = 0;
	return(0);
}

/*********************************************************************
 *
 *  Enable receive unit.
 *  
 **********************************************************************/
static void
em_initialize_receive_unit(struct adapter * adapter)
{
	u_int32_t       reg_rctl;
	u_int32_t       reg_rxcsum;
	struct ifnet    *ifp;
	u_int64_t	bus_addr;

        INIT_DEBUGOUT("em_initialize_receive_unit: begin");
	ifp = adapter->ifp;

	/* Make sure receives are disabled while setting up the descriptor ring */
	E1000_WRITE_REG(&adapter->hw, RCTL, 0);

	/* Set the Receive Delay Timer Register */
	E1000_WRITE_REG(&adapter->hw, RDTR, 
			adapter->rx_int_delay.value | E1000_RDT_FPDB);

	if(adapter->hw.mac_type >= em_82540) {
		E1000_WRITE_REG(&adapter->hw, RADV,
		    adapter->rx_abs_int_delay.value);

                /* Set the interrupt throttling rate.  Value is calculated
                 * as DEFAULT_ITR = 1/(MAX_INTS_PER_SEC * 256ns) */
#define MAX_INTS_PER_SEC        8000
#define DEFAULT_ITR             1000000000/(MAX_INTS_PER_SEC * 256)
                E1000_WRITE_REG(&adapter->hw, ITR, DEFAULT_ITR);
        }       

	/* Setup the Base and Length of the Rx Descriptor Ring */
	bus_addr = adapter->rxdma.dma_paddr;
	E1000_WRITE_REG(&adapter->hw, RDBAL, (u_int32_t)bus_addr);
	E1000_WRITE_REG(&adapter->hw, RDBAH, (u_int32_t)(bus_addr >> 32));
	E1000_WRITE_REG(&adapter->hw, RDLEN, adapter->num_rx_desc *
			sizeof(struct em_rx_desc));

	/* Setup the HW Rx Head and Tail Descriptor Pointers */
	E1000_WRITE_REG(&adapter->hw, RDH, 0);
	E1000_WRITE_REG(&adapter->hw, RDT, adapter->num_rx_desc - 1);

	/* Setup the Receive Control Register */
	reg_rctl = E1000_RCTL_EN | E1000_RCTL_BAM | E1000_RCTL_LBM_NO |
		   E1000_RCTL_RDMTS_HALF |
		   (adapter->hw.mc_filter_type << E1000_RCTL_MO_SHIFT);

	if (adapter->hw.tbi_compatibility_on == TRUE)
		reg_rctl |= E1000_RCTL_SBP;


	switch (adapter->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 (ifp->if_mtu > ETHERMTU)
		reg_rctl |= E1000_RCTL_LPE;

	/* Enable 82543 Receive Checksum Offload for TCP and UDP */
	if ((adapter->hw.mac_type >= em_82543) && 
	    (ifp->if_capenable & IFCAP_RXCSUM)) {
		reg_rxcsum = E1000_READ_REG(&adapter->hw, RXCSUM);
		reg_rxcsum |= (E1000_RXCSUM_IPOFL | E1000_RXCSUM_TUOFL);
		E1000_WRITE_REG(&adapter->hw, RXCSUM, reg_rxcsum);
	}

	/* Enable Receives */
	E1000_WRITE_REG(&adapter->hw, RCTL, reg_rctl);

	return;
}

/*********************************************************************
 *
 *  Free receive related data structures.
 *
 **********************************************************************/
static void
em_free_receive_structures(struct adapter *adapter)
{
        struct em_buffer   *rx_buffer;
        int             i;

        INIT_DEBUGOUT("free_receive_structures: begin");

        if (adapter->rx_buffer_area != NULL) {
                rx_buffer = adapter->rx_buffer_area;
                for (i = 0; i < adapter->num_rx_desc; i++, rx_buffer++) {
			if (rx_buffer->m_head != NULL) {
				bus_dmamap_sync(adapter->rxtag, rx_buffer->map,
				    BUS_DMASYNC_POSTREAD);
				bus_dmamap_unload(adapter->rxtag,
				    rx_buffer->map);
				m_freem(rx_buffer->m_head);
				rx_buffer->m_head = NULL;
			} else if (rx_buffer->map != NULL)
				bus_dmamap_unload(adapter->rxtag,
				    rx_buffer->map);
                        if (rx_buffer->map != NULL) {
				bus_dmamap_destroy(adapter->rxtag,
				    rx_buffer->map);
				rx_buffer->map = NULL;
			}
                }
        }
        if (adapter->rx_buffer_area != NULL) {
                free(adapter->rx_buffer_area, M_DEVBUF);
                adapter->rx_buffer_area = NULL;
        }
        if (adapter->rxtag != NULL) {
                bus_dma_tag_destroy(adapter->rxtag);
                adapter->rxtag = NULL;
        }
        return;
}

/*********************************************************************
 *
 *  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.
 *
 *  We loop at most count times if count is > 0, or until done if
 *  count < 0.
 *
 *********************************************************************/
static int
em_process_receive_interrupts(struct adapter * adapter, int count)
{
	struct ifnet        *ifp;
	struct mbuf         *mp;
	u_int8_t            accept_frame = 0;
 	u_int8_t            eop = 0;
	u_int16_t           len, desc_len, prev_len_adj;
	int                 i;

	/* Pointer to the receive descriptor being examined. */
	struct em_rx_desc   *current_desc;

	ifp = adapter->ifp;
	i = adapter->next_rx_desc_to_check;
        current_desc = &adapter->rx_desc_base[i];
	bus_dmamap_sync(adapter->rxdma.dma_tag, adapter->rxdma.dma_map,
	    BUS_DMASYNC_POSTREAD);

	if (!((current_desc->status) & E1000_RXD_STAT_DD)) {
		return (0);
	}

	while ((current_desc->status & E1000_RXD_STAT_DD) &&
		    (count != 0) &&
		    (ifp->if_drv_flags & IFF_DRV_RUNNING)) {
		struct mbuf *m = NULL;

		mp = adapter->rx_buffer_area[i].m_head;
		bus_dmamap_sync(adapter->rxtag, adapter->rx_buffer_area[i].map,
		    BUS_DMASYNC_POSTREAD);
		bus_dmamap_unload(adapter->rxtag,
		    adapter->rx_buffer_area[i].map);

		accept_frame = 1;
		prev_len_adj = 0;
                desc_len = le16toh(current_desc->length);
		if (current_desc->status & E1000_RXD_STAT_EOP) {
			count--;
			eop = 1;
			if (desc_len < ETHER_CRC_LEN) {
                                len = 0;
                                prev_len_adj = ETHER_CRC_LEN - desc_len;
                        }
                        else {
                                len = desc_len - ETHER_CRC_LEN;
                        }
		} else {
			eop = 0;
			len = desc_len;
		}

		if (current_desc->errors & E1000_RXD_ERR_FRAME_ERR_MASK) {
			u_int8_t            last_byte;
			u_int32_t           pkt_len = desc_len;

			if (adapter->fmp != NULL)
				pkt_len += adapter->fmp->m_pkthdr.len; 
 
			last_byte = *(mtod(mp, caddr_t) + desc_len - 1);			

			if (TBI_ACCEPT(&adapter->hw, current_desc->status, 
				       current_desc->errors, 
				       pkt_len, last_byte)) {
				em_tbi_adjust_stats(&adapter->hw, 
						    &adapter->stats, 
						    pkt_len, 
						    adapter->hw.mac_addr);
				if (len > 0) len--;
			} 
			else {
				accept_frame = 0;
			}
		}

		if (accept_frame) {

			if (em_get_buf(i, adapter, NULL) == ENOBUFS) {
				adapter->dropped_pkts++;
				em_get_buf(i, adapter, mp);
				if (adapter->fmp != NULL) 
					m_freem(adapter->fmp);
				adapter->fmp = NULL;
				adapter->lmp = NULL;
				break;
			}

			/* Assign correct length to the current fragment */
			mp->m_len = len;

			if (adapter->fmp == NULL) {
				mp->m_pkthdr.len = len;
				adapter->fmp = mp;	 /* Store the first mbuf */
				adapter->lmp = mp;
			} else {
				/* Chain mbuf's together */
				mp->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) {
					adapter->lmp->m_len -= prev_len_adj;
					adapter->fmp->m_pkthdr.len -= prev_len_adj;
				}
				adapter->lmp->m_next = mp;
				adapter->lmp = adapter->lmp->m_next;
				adapter->fmp->m_pkthdr.len += len;
			}

                        if (eop) {
                                adapter->fmp->m_pkthdr.rcvif = ifp;
				ifp->if_ipackets++;
                                em_receive_checksum(adapter, current_desc,
                                                    adapter->fmp);
#ifndef __NO_STRICT_ALIGNMENT
				if (ifp->if_mtu > ETHERMTU &&
				    em_fixup_rx(adapter) != 0)
					goto skip;

#endif
                                if (current_desc->status & E1000_RXD_STAT_VP)
					VLAN_INPUT_TAG(ifp, adapter->fmp,
					    (le16toh(current_desc->special) &
					    E1000_RXD_SPC_VLAN_MASK));
#ifndef __NO_STRICT_ALIGNMENT
skip:
#endif
				m = adapter->fmp;
				adapter->fmp = NULL;
				adapter->lmp = NULL;
                        }
		} else {
			adapter->dropped_pkts++;
			em_get_buf(i, adapter, mp);
			if (adapter->fmp != NULL) 
				m_freem(adapter->fmp);
			adapter->fmp = NULL;
			adapter->lmp = NULL;
		}

		/* Zero out the receive descriptors status  */
		current_desc->status = 0;
		bus_dmamap_sync(adapter->rxdma.dma_tag, adapter->rxdma.dma_map,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
 
                /* Advance our pointers to the next descriptor */
		if (++i == adapter->num_rx_desc)
			i = 0;
		if (m != NULL) {
			adapter->next_rx_desc_to_check = i;
			(*ifp->if_input)(ifp, m);
			i = adapter->next_rx_desc_to_check;
		}
		current_desc = &adapter->rx_desc_base[i];
	}
	adapter->next_rx_desc_to_check = i;

	/* Advance the E1000's Receive Queue #0  "Tail Pointer". */
	if (--i < 0) i = adapter->num_rx_desc - 1;
	E1000_WRITE_REG(&adapter->hw, RDT, i);

	if (!((current_desc->status) & E1000_RXD_STAT_DD)) {
		return (0);
	}
	return (1);
}

#ifndef __NO_STRICT_ALIGNMENT
/*
 * When jumbo frames are enabled we should realign entire payload on
 * architecures with strict alignment. This is serious design mistake of 8254x
 * as it nullifies DMA operations. 8254x just allows RX buffer size to be
 * 2048/4096/8192/16384. What we really want is 2048 - ETHER_ALIGN to align its
 * payload. On architecures without strict alignment restrictions 8254x still
 * performs unaligned memory access which would reduce the performance too. 
 * To avoid copying over an entire frame to align, we allocate a new mbuf and
 * copy ethernet header to the new mbuf. The new mbuf is prepended into the
 * existing mbuf chain.
 *
 * Be aware, best performance of the 8254x is achived only when jumbo frame is
 * not used at all on architectures with strict alignment.
 */
static int
em_fixup_rx(struct adapter *adapter)
{
	struct mbuf *m, *n;
	int error;

	error = 0;
	m = adapter->fmp;
	if (m->m_len <= (MCLBYTES - ETHER_HDR_LEN)) {
		bcopy(m->m_data, m->m_data + ETHER_HDR_LEN, m->m_len);
		m->m_data += ETHER_HDR_LEN;
	} else {
		MGETHDR(n, M_DONTWAIT, MT_DATA);
		if (n != NULL) {
			bcopy(m->m_data, n->m_data, ETHER_HDR_LEN);
			m->m_data += ETHER_HDR_LEN;
			m->m_len -= ETHER_HDR_LEN;
			n->m_len = ETHER_HDR_LEN;
			M_MOVE_PKTHDR(n, m);
			n->m_next = m;
			adapter->fmp = n;
		} else {
			adapter->dropped_pkts++;
			m_freem(adapter->fmp);
			adapter->fmp = NULL;
			error = ENOMEM;
		}
	}

	return (error);
}
#endif

/*********************************************************************
 *
 *  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.
 *
 *********************************************************************/
static void
em_receive_checksum(struct adapter *adapter,
		    struct em_rx_desc *rx_desc,
		    struct mbuf *mp)
{
	/* 82543 or newer only */
	if ((adapter->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 = CSUM_IP_CHECKED;
			mp->m_pkthdr.csum_flags |= CSUM_IP_VALID;

		} 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 |= 
			(CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
			mp->m_pkthdr.csum_data = htons(0xffff);
		}
	}

	return;
}


static void 
em_enable_vlans(struct adapter *adapter)
{
	uint32_t ctrl;

	E1000_WRITE_REG(&adapter->hw, VET, ETHERTYPE_VLAN);

	ctrl = E1000_READ_REG(&adapter->hw, CTRL);
	ctrl |= E1000_CTRL_VME; 
	E1000_WRITE_REG(&adapter->hw, CTRL, ctrl);

	return;
}

static void
em_disable_vlans(struct adapter *adapter)
{
	uint32_t ctrl;

	ctrl = E1000_READ_REG(&adapter->hw, CTRL);
	ctrl &= ~E1000_CTRL_VME;
	E1000_WRITE_REG(&adapter->hw, CTRL, ctrl);

	return;
}

static void
em_enable_intr(struct adapter * adapter)
{
	E1000_WRITE_REG(&adapter->hw, IMS, (IMS_ENABLE_MASK));
	return;
}

static void
em_disable_intr(struct adapter *adapter)
{
	/*
	 * The first version of 82542 had an errata where when link was forced it
	 * would stay up even 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 in the in the ISR.  For this to work correctly the Sequence error 
	 * interrupt had to be enabled all the time.
	 */

	if (adapter->hw.mac_type == em_82542_rev2_0)
	    E1000_WRITE_REG(&adapter->hw, IMC,
	        (0xffffffff & ~E1000_IMC_RXSEQ));
	else
	    E1000_WRITE_REG(&adapter->hw, IMC,
	        0xffffffff);
	return;
}

static int
em_is_valid_ether_addr(u_int8_t *addr)
{
        char zero_addr[6] = { 0, 0, 0, 0, 0, 0 };
                                
        if ((addr[0] & 1) || (!bcmp(addr, zero_addr, ETHER_ADDR_LEN))) {
                return (FALSE);
        }

        return(TRUE);
}

void 
em_write_pci_cfg(struct em_hw *hw,
		      uint32_t reg,
		      uint16_t *value)
{
	pci_write_config(((struct em_osdep *)hw->back)->dev, reg, 
			 *value, 2);
}

void 
em_read_pci_cfg(struct em_hw *hw, uint32_t reg,
		     uint16_t *value)
{
	*value = pci_read_config(((struct em_osdep *)hw->back)->dev,
				 reg, 2);
	return;
}

void
em_pci_set_mwi(struct em_hw *hw)
{
        pci_write_config(((struct em_osdep *)hw->back)->dev,
                         PCIR_COMMAND,
                         (hw->pci_cmd_word | CMD_MEM_WRT_INVALIDATE), 2);
        return;
}

void
em_pci_clear_mwi(struct em_hw *hw)
{
        pci_write_config(((struct em_osdep *)hw->back)->dev,
                         PCIR_COMMAND,
                         (hw->pci_cmd_word & ~CMD_MEM_WRT_INVALIDATE), 2);
        return;
}

/*********************************************************************
* 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)
*
*** *********************************************************************/
static u_int32_t
em_fill_descriptors (bus_addr_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;
}

/**********************************************************************
 *
 *  Update the board statistics counters. 
 *
 **********************************************************************/
static void
em_update_stats_counters(struct adapter *adapter)
{
	struct ifnet   *ifp;

	if(adapter->hw.media_type == em_media_type_copper ||
	   (E1000_READ_REG(&adapter->hw, STATUS) & E1000_STATUS_LU)) {
		adapter->stats.symerrs += E1000_READ_REG(&adapter->hw, SYMERRS);
		adapter->stats.sec += E1000_READ_REG(&adapter->hw, SEC);
	}
	adapter->stats.crcerrs += E1000_READ_REG(&adapter->hw, CRCERRS);
	adapter->stats.mpc += E1000_READ_REG(&adapter->hw, MPC);
	adapter->stats.scc += E1000_READ_REG(&adapter->hw, SCC);
	adapter->stats.ecol += E1000_READ_REG(&adapter->hw, ECOL);

	adapter->stats.mcc += E1000_READ_REG(&adapter->hw, MCC);
	adapter->stats.latecol += E1000_READ_REG(&adapter->hw, LATECOL);
	adapter->stats.colc += E1000_READ_REG(&adapter->hw, COLC);
	adapter->stats.dc += E1000_READ_REG(&adapter->hw, DC);
	adapter->stats.rlec += E1000_READ_REG(&adapter->hw, RLEC);
	adapter->stats.xonrxc += E1000_READ_REG(&adapter->hw, XONRXC);
	adapter->stats.xontxc += E1000_READ_REG(&adapter->hw, XONTXC);
	adapter->stats.xoffrxc += E1000_READ_REG(&adapter->hw, XOFFRXC);
	adapter->stats.xofftxc += E1000_READ_REG(&adapter->hw, XOFFTXC);
	adapter->stats.fcruc += E1000_READ_REG(&adapter->hw, FCRUC);
	adapter->stats.prc64 += E1000_READ_REG(&adapter->hw, PRC64);
	adapter->stats.prc127 += E1000_READ_REG(&adapter->hw, PRC127);
	adapter->stats.prc255 += E1000_READ_REG(&adapter->hw, PRC255);
	adapter->stats.prc511 += E1000_READ_REG(&adapter->hw, PRC511);
	adapter->stats.prc1023 += E1000_READ_REG(&adapter->hw, PRC1023);
	adapter->stats.prc1522 += E1000_READ_REG(&adapter->hw, PRC1522);
	adapter->stats.gprc += E1000_READ_REG(&adapter->hw, GPRC);
	adapter->stats.bprc += E1000_READ_REG(&adapter->hw, BPRC);
	adapter->stats.mprc += E1000_READ_REG(&adapter->hw, MPRC);
	adapter->stats.gptc += E1000_READ_REG(&adapter->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 */

	adapter->stats.gorcl += E1000_READ_REG(&adapter->hw, GORCL); 
	adapter->stats.gorch += E1000_READ_REG(&adapter->hw, GORCH);
	adapter->stats.gotcl += E1000_READ_REG(&adapter->hw, GOTCL);
	adapter->stats.gotch += E1000_READ_REG(&adapter->hw, GOTCH);

	adapter->stats.rnbc += E1000_READ_REG(&adapter->hw, RNBC);
	adapter->stats.ruc += E1000_READ_REG(&adapter->hw, RUC);
	adapter->stats.rfc += E1000_READ_REG(&adapter->hw, RFC);
	adapter->stats.roc += E1000_READ_REG(&adapter->hw, ROC);
	adapter->stats.rjc += E1000_READ_REG(&adapter->hw, RJC);

	adapter->stats.torl += E1000_READ_REG(&adapter->hw, TORL);
	adapter->stats.torh += E1000_READ_REG(&adapter->hw, TORH);
	adapter->stats.totl += E1000_READ_REG(&adapter->hw, TOTL);
	adapter->stats.toth += E1000_READ_REG(&adapter->hw, TOTH);

	adapter->stats.tpr += E1000_READ_REG(&adapter->hw, TPR);
	adapter->stats.tpt += E1000_READ_REG(&adapter->hw, TPT);
	adapter->stats.ptc64 += E1000_READ_REG(&adapter->hw, PTC64);
	adapter->stats.ptc127 += E1000_READ_REG(&adapter->hw, PTC127);
	adapter->stats.ptc255 += E1000_READ_REG(&adapter->hw, PTC255);
	adapter->stats.ptc511 += E1000_READ_REG(&adapter->hw, PTC511);
	adapter->stats.ptc1023 += E1000_READ_REG(&adapter->hw, PTC1023);
	adapter->stats.ptc1522 += E1000_READ_REG(&adapter->hw, PTC1522);
	adapter->stats.mptc += E1000_READ_REG(&adapter->hw, MPTC);
	adapter->stats.bptc += E1000_READ_REG(&adapter->hw, BPTC);

	if (adapter->hw.mac_type >= em_82543) {
		adapter->stats.algnerrc += 
		E1000_READ_REG(&adapter->hw, ALGNERRC);
		adapter->stats.rxerrc += 
		E1000_READ_REG(&adapter->hw, RXERRC);
		adapter->stats.tncrs += 
		E1000_READ_REG(&adapter->hw, TNCRS);
		adapter->stats.cexterr += 
		E1000_READ_REG(&adapter->hw, CEXTERR);
		adapter->stats.tsctc += 
		E1000_READ_REG(&adapter->hw, TSCTC);
		adapter->stats.tsctfc += 
		E1000_READ_REG(&adapter->hw, TSCTFC);
	}
	ifp = adapter->ifp;

	ifp->if_collisions = adapter->stats.colc;

	/* Rx Errors */
	ifp->if_ierrors =
	adapter->dropped_pkts +
	adapter->stats.rxerrc +
	adapter->stats.crcerrs +
	adapter->stats.algnerrc +
	adapter->stats.rlec +
	adapter->stats.mpc + adapter->stats.cexterr;

	/* Tx Errors */
	ifp->if_oerrors = adapter->stats.ecol + adapter->stats.latecol +
	    adapter->watchdog_events;

}


/**********************************************************************
 *
 *  This routine is called only when em_display_debug_stats is enabled.
 *  This routine provides a way to take a look at important statistics
 *  maintained by the driver and hardware.
 *
 **********************************************************************/
static void
em_print_debug_info(struct adapter *adapter)
{
	int unit = adapter->unit;
	uint8_t *hw_addr = adapter->hw.hw_addr;
 
	printf("em%d: Adapter hardware address = %p \n", unit, hw_addr);
	printf("em%d: CTRL = 0x%x RCTL = 0x%x \n", unit, 
	    E1000_READ_REG(&adapter->hw, CTRL),
	    E1000_READ_REG(&adapter->hw, RCTL)); 
	printf("em%d: Packet buffer = Tx=%dk Rx=%dk \n", unit, 
	    ((E1000_READ_REG(&adapter->hw, PBA) & 0xffff0000) >> 16),\
	    (E1000_READ_REG(&adapter->hw, PBA) & 0xffff) );
	printf("em%d: Flow control watermarks high = %d low = %d\n", unit, 
	    adapter->hw.fc_high_water,
	    adapter->hw.fc_low_water);
	printf("em%d: tx_int_delay = %d, tx_abs_int_delay = %d\n", unit, 
	    E1000_READ_REG(&adapter->hw, TIDV),
	    E1000_READ_REG(&adapter->hw, TADV));
	printf("em%d: rx_int_delay = %d, rx_abs_int_delay = %d\n", unit, 
	    E1000_READ_REG(&adapter->hw, RDTR),
	    E1000_READ_REG(&adapter->hw, RADV));
	printf("em%d: fifo workaround = %lld, fifo_reset_count = %lld\n",
	    unit, (long long)adapter->tx_fifo_wrk_cnt, 
	    (long long)adapter->tx_fifo_reset_cnt);
	printf("em%d: hw tdh = %d, hw tdt = %d\n", unit,
	    E1000_READ_REG(&adapter->hw, TDH),
	    E1000_READ_REG(&adapter->hw, TDT));
	printf("em%d: Num Tx descriptors avail = %d\n", unit,
	    adapter->num_tx_desc_avail);
	printf("em%d: Tx Descriptors not avail1 = %ld\n", unit,
	    adapter->no_tx_desc_avail1);
	printf("em%d: Tx Descriptors not avail2 = %ld\n", unit,
	    adapter->no_tx_desc_avail2);
	printf("em%d: Std mbuf failed = %ld\n", unit,
	    adapter->mbuf_alloc_failed);
	printf("em%d: Std mbuf cluster failed = %ld\n", unit,
	    adapter->mbuf_cluster_failed);
	printf("em%d: Driver dropped packets = %ld\n", unit,
	    adapter->dropped_pkts);

	return;
}

static void
em_print_hw_stats(struct adapter *adapter)
{
        int unit = adapter->unit;

        printf("em%d: Excessive collisions = %lld\n", unit,
               (long long)adapter->stats.ecol);
        printf("em%d: Symbol errors = %lld\n", unit,
               (long long)adapter->stats.symerrs);
        printf("em%d: Sequence errors = %lld\n", unit,
               (long long)adapter->stats.sec);
        printf("em%d: Defer count = %lld\n", unit,
               (long long)adapter->stats.dc);

        printf("em%d: Missed Packets = %lld\n", unit,
               (long long)adapter->stats.mpc);
        printf("em%d: Receive No Buffers = %lld\n", unit,
               (long long)adapter->stats.rnbc);
        printf("em%d: Receive length errors = %lld\n", unit,
               (long long)adapter->stats.rlec);
        printf("em%d: Receive errors = %lld\n", unit,
               (long long)adapter->stats.rxerrc);
        printf("em%d: Crc errors = %lld\n", unit,
               (long long)adapter->stats.crcerrs);
        printf("em%d: Alignment errors = %lld\n", unit,
               (long long)adapter->stats.algnerrc);
        printf("em%d: Carrier extension errors = %lld\n", unit,
               (long long)adapter->stats.cexterr);
	printf("em%d: RX overruns = %ld\n", unit, adapter->rx_overruns);
	printf("em%d: watchdog timeouts = %ld\n", unit,
		adapter->watchdog_events);

        printf("em%d: XON Rcvd = %lld\n", unit,
               (long long)adapter->stats.xonrxc);
        printf("em%d: XON Xmtd = %lld\n", unit,
               (long long)adapter->stats.xontxc);
        printf("em%d: XOFF Rcvd = %lld\n", unit,
               (long long)adapter->stats.xoffrxc);
        printf("em%d: XOFF Xmtd = %lld\n", unit,
               (long long)adapter->stats.xofftxc);

        printf("em%d: Good Packets Rcvd = %lld\n", unit,
               (long long)adapter->stats.gprc);
        printf("em%d: Good Packets Xmtd = %lld\n", unit,
               (long long)adapter->stats.gptc);

        return;
}

static int
em_sysctl_debug_info(SYSCTL_HANDLER_ARGS)
{
        int error;
        int result;
        struct adapter *adapter;

        result = -1;
        error = sysctl_handle_int(oidp, &result, 0, req);

        if (error || !req->newptr)
                return (error);

        if (result == 1) {
                adapter = (struct adapter *)arg1;
                em_print_debug_info(adapter);
        }

        return error;
}


static int
em_sysctl_stats(SYSCTL_HANDLER_ARGS)
{
        int error;
        int result;
        struct adapter *adapter;

        result = -1;
        error = sysctl_handle_int(oidp, &result, 0, req);

        if (error || !req->newptr)
                return (error);

        if (result == 1) {
                adapter = (struct adapter *)arg1;
                em_print_hw_stats(adapter);
        }

        return error;
}

static int
em_sysctl_int_delay(SYSCTL_HANDLER_ARGS)
{
	struct em_int_delay_info *info;
	struct adapter *adapter;
	u_int32_t regval;
	int error;
	int usecs;
	int ticks;

	info = (struct em_int_delay_info *)arg1;
	usecs = info->value;
	error = sysctl_handle_int(oidp, &usecs, 0, req);
	if (error != 0 || req->newptr == NULL)
		return error;
	if (usecs < 0 || usecs > E1000_TICKS_TO_USECS(65535))
		return EINVAL;
	info->value = usecs;
	ticks = E1000_USECS_TO_TICKS(usecs);

	adapter = info->adapter;
	
	EM_LOCK(adapter);
	regval = E1000_READ_OFFSET(&adapter->hw, info->offset);
	regval = (regval & ~0xffff) | (ticks & 0xffff);
	/* Handle a few special cases. */
	switch (info->offset) {
	case E1000_RDTR:
	case E1000_82542_RDTR:
		regval |= E1000_RDT_FPDB;
		break;
	case E1000_TIDV:
	case E1000_82542_TIDV:
		if (ticks == 0) {
			adapter->txd_cmd &= ~E1000_TXD_CMD_IDE;
			/* Don't write 0 into the TIDV register. */
			regval++;
		} else
			adapter->txd_cmd |= E1000_TXD_CMD_IDE;
		break;
	}
	E1000_WRITE_OFFSET(&adapter->hw, info->offset, regval);
	EM_UNLOCK(adapter);
	return 0;
}

static void
em_add_int_delay_sysctl(struct adapter *adapter, const char *name,
    const char *description, struct em_int_delay_info *info,
    int offset, int value)
{
	info->adapter = adapter;
	info->offset = offset;
	info->value = value;
	SYSCTL_ADD_PROC(device_get_sysctl_ctx(adapter->dev),
	    SYSCTL_CHILDREN(device_get_sysctl_tree(adapter->dev)),
	    OID_AUTO, name, CTLTYPE_INT|CTLFLAG_RW,
	    info, 0, em_sysctl_int_delay, "I", description);
}

#ifndef NO_EM_FASTINTR
static void
em_add_int_process_limit(struct adapter *adapter, const char *name,
    const char *description, int *limit, int value)
{
	*limit = value;
	SYSCTL_ADD_INT(device_get_sysctl_ctx(adapter->dev),
	    SYSCTL_CHILDREN(device_get_sysctl_tree(adapter->dev)),
	    OID_AUTO, name, CTLTYPE_INT|CTLFLAG_RW, limit, value, description);
}
#endif