drivers/net/ixgb/ixgb_main.c

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

  Intel PRO/10GbE Linux driver
  Copyright(c) 1999 - 2006 Intel Corporation.

  This program is free software; you can redistribute it and/or modify it
  under the terms and conditions of the GNU General Public License,
  version 2, as published by the Free Software Foundation.

  This program is distributed in the hope it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  more details.

  You should have received a copy of the GNU General Public License along with
  this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.

  The full GNU General Public License is included in this distribution in
  the file called "COPYING".

  Contact Information:
  Linux NICS <linux.nics@intel.com>
  e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
  Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497

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

#include "ixgb.h"

char ixgb_driver_name[] = "ixgb";
static char ixgb_driver_string[] = "Intel(R) PRO/10GbE Network Driver";

#ifndef CONFIG_IXGB_NAPI
#define DRIVERNAPI
#else
#define DRIVERNAPI "-NAPI"
#endif
#define DRV_VERSION		"1.0.126-k4"DRIVERNAPI
const char ixgb_driver_version[] = DRV_VERSION;
static const char ixgb_copyright[] = "Copyright (c) 1999-2006 Intel Corporation.";

#define IXGB_CB_LENGTH 256
static unsigned int copybreak __read_mostly = IXGB_CB_LENGTH;
module_param(copybreak, uint, 0644);
MODULE_PARM_DESC(copybreak,
	"Maximum size of packet that is copied to a new buffer on receive");

/* ixgb_pci_tbl - PCI Device ID Table
 *
 * Wildcard entries (PCI_ANY_ID) should come last
 * Last entry must be all 0s
 *
 * { Vendor ID, Device ID, SubVendor ID, SubDevice ID,
 *   Class, Class Mask, private data (not used) }
 */
static struct pci_device_id ixgb_pci_tbl[] = {
	{INTEL_VENDOR_ID, IXGB_DEVICE_ID_82597EX,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{INTEL_VENDOR_ID, IXGB_DEVICE_ID_82597EX_CX4,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{INTEL_VENDOR_ID, IXGB_DEVICE_ID_82597EX_SR,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{INTEL_VENDOR_ID, IXGB_DEVICE_ID_82597EX_LR,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},

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

MODULE_DEVICE_TABLE(pci, ixgb_pci_tbl);

/* Local Function Prototypes */
static int ixgb_init_module(void);
static void ixgb_exit_module(void);
static int ixgb_probe(struct pci_dev *pdev, const struct pci_device_id *ent);
static void __devexit ixgb_remove(struct pci_dev *pdev);
static int ixgb_sw_init(struct ixgb_adapter *adapter);
static int ixgb_open(struct net_device *netdev);
static int ixgb_close(struct net_device *netdev);
static void ixgb_configure_tx(struct ixgb_adapter *adapter);
static void ixgb_configure_rx(struct ixgb_adapter *adapter);
static void ixgb_setup_rctl(struct ixgb_adapter *adapter);
static void ixgb_clean_tx_ring(struct ixgb_adapter *adapter);
static void ixgb_clean_rx_ring(struct ixgb_adapter *adapter);
static void ixgb_set_multi(struct net_device *netdev);
static void ixgb_watchdog(unsigned long data);
static int ixgb_xmit_frame(struct sk_buff *skb, struct net_device *netdev);
static struct net_device_stats *ixgb_get_stats(struct net_device *netdev);
static int ixgb_change_mtu(struct net_device *netdev, int new_mtu);
static int ixgb_set_mac(struct net_device *netdev, void *p);
static irqreturn_t ixgb_intr(int irq, void *data);
static bool ixgb_clean_tx_irq(struct ixgb_adapter *adapter);

#ifdef CONFIG_IXGB_NAPI
static int ixgb_clean(struct napi_struct *, int);
static bool ixgb_clean_rx_irq(struct ixgb_adapter *, int *, int);
#else
static bool ixgb_clean_rx_irq(struct ixgb_adapter *);
#endif
static void ixgb_alloc_rx_buffers(struct ixgb_adapter *);

static void ixgb_tx_timeout(struct net_device *dev);
static void ixgb_tx_timeout_task(struct work_struct *work);

static void ixgb_vlan_rx_register(struct net_device *netdev,
                                  struct vlan_group *grp);
static void ixgb_vlan_rx_add_vid(struct net_device *netdev, u16 vid);
static void ixgb_vlan_rx_kill_vid(struct net_device *netdev, u16 vid);
static void ixgb_restore_vlan(struct ixgb_adapter *adapter);

#ifdef CONFIG_NET_POLL_CONTROLLER
/* for netdump / net console */
static void ixgb_netpoll(struct net_device *dev);
#endif

static pci_ers_result_t ixgb_io_error_detected (struct pci_dev *pdev,
                             enum pci_channel_state state);
static pci_ers_result_t ixgb_io_slot_reset (struct pci_dev *pdev);
static void ixgb_io_resume (struct pci_dev *pdev);

static struct pci_error_handlers ixgb_err_handler = {
	.error_detected = ixgb_io_error_detected,
	.slot_reset = ixgb_io_slot_reset,
	.resume = ixgb_io_resume,
};

static struct pci_driver ixgb_driver = {
	.name     = ixgb_driver_name,
	.id_table = ixgb_pci_tbl,
	.probe    = ixgb_probe,
	.remove   = __devexit_p(ixgb_remove),
	.err_handler = &ixgb_err_handler
};

MODULE_AUTHOR("Intel Corporation, <linux.nics@intel.com>");
MODULE_DESCRIPTION("Intel(R) PRO/10GbE Network Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

#define DEFAULT_DEBUG_LEVEL_SHIFT 3
static int debug = DEFAULT_DEBUG_LEVEL_SHIFT;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");

/**
 * ixgb_init_module - Driver Registration Routine
 *
 * ixgb_init_module is the first routine called when the driver is
 * loaded. All it does is register with the PCI subsystem.
 **/

static int __init
ixgb_init_module(void)
{
	printk(KERN_INFO "%s - version %s\n",
	       ixgb_driver_string, ixgb_driver_version);

	printk(KERN_INFO "%s\n", ixgb_copyright);

	return pci_register_driver(&ixgb_driver);
}

module_init(ixgb_init_module);

/**
 * ixgb_exit_module - Driver Exit Cleanup Routine
 *
 * ixgb_exit_module is called just before the driver is removed
 * from memory.
 **/

static void __exit
ixgb_exit_module(void)
{
	pci_unregister_driver(&ixgb_driver);
}

module_exit(ixgb_exit_module);

/**
 * ixgb_irq_disable - Mask off interrupt generation on the NIC
 * @adapter: board private structure
 **/

static void
ixgb_irq_disable(struct ixgb_adapter *adapter)
{
	IXGB_WRITE_REG(&adapter->hw, IMC, ~0);
	IXGB_WRITE_FLUSH(&adapter->hw);
	synchronize_irq(adapter->pdev->irq);
}

/**
 * ixgb_irq_enable - Enable default interrupt generation settings
 * @adapter: board private structure
 **/

static void
ixgb_irq_enable(struct ixgb_adapter *adapter)
{
	u32 val = IXGB_INT_RXT0 | IXGB_INT_RXDMT0 |
		  IXGB_INT_TXDW | IXGB_INT_LSC;
	if (adapter->hw.subsystem_vendor_id == SUN_SUBVENDOR_ID)
		val |= IXGB_INT_GPI0;
	IXGB_WRITE_REG(&adapter->hw, IMS, val);
	IXGB_WRITE_FLUSH(&adapter->hw);
}

int
ixgb_up(struct ixgb_adapter *adapter)
{
	struct net_device *netdev = adapter->netdev;
	int err, irq_flags = IRQF_SHARED;
	int max_frame = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
	struct ixgb_hw *hw = &adapter->hw;

	/* hardware has been reset, we need to reload some things */

	ixgb_rar_set(hw, netdev->dev_addr, 0);
	ixgb_set_multi(netdev);

	ixgb_restore_vlan(adapter);

	ixgb_configure_tx(adapter);
	ixgb_setup_rctl(adapter);
	ixgb_configure_rx(adapter);
	ixgb_alloc_rx_buffers(adapter);

	/* disable interrupts and get the hardware into a known state */
	IXGB_WRITE_REG(&adapter->hw, IMC, 0xffffffff);

	/* only enable MSI if bus is in PCI-X mode */
	if (IXGB_READ_REG(&adapter->hw, STATUS) & IXGB_STATUS_PCIX_MODE) {
		err = pci_enable_msi(adapter->pdev);
		if (!err) {
			adapter->have_msi = 1;
			irq_flags = 0;
		}
		/* proceed to try to request regular interrupt */
	}

	err = request_irq(adapter->pdev->irq, &ixgb_intr, irq_flags,
	                  netdev->name, netdev);
	if (err) {
		if (adapter->have_msi)
			pci_disable_msi(adapter->pdev);
		DPRINTK(PROBE, ERR,
		 "Unable to allocate interrupt Error: %d\n", err);
		return err;
	}

	if ((hw->max_frame_size != max_frame) ||
		(hw->max_frame_size !=
		(IXGB_READ_REG(hw, MFS) >> IXGB_MFS_SHIFT))) {

		hw->max_frame_size = max_frame;

		IXGB_WRITE_REG(hw, MFS, hw->max_frame_size << IXGB_MFS_SHIFT);

		if (hw->max_frame_size >
		   IXGB_MAX_ENET_FRAME_SIZE_WITHOUT_FCS + ENET_FCS_LENGTH) {
			u32 ctrl0 = IXGB_READ_REG(hw, CTRL0);

			if (!(ctrl0 & IXGB_CTRL0_JFE)) {
				ctrl0 |= IXGB_CTRL0_JFE;
				IXGB_WRITE_REG(hw, CTRL0, ctrl0);
			}
		}
	}

	clear_bit(__IXGB_DOWN, &adapter->flags);

#ifdef CONFIG_IXGB_NAPI
	napi_enable(&adapter->napi);
#endif
	ixgb_irq_enable(adapter);

	mod_timer(&adapter->watchdog_timer, jiffies);

	return 0;
}

void
ixgb_down(struct ixgb_adapter *adapter, bool kill_watchdog)
{
	struct net_device *netdev = adapter->netdev;

	/* prevent the interrupt handler from restarting watchdog */
	set_bit(__IXGB_DOWN, &adapter->flags);

#ifdef CONFIG_IXGB_NAPI
	napi_disable(&adapter->napi);
#endif
	/* waiting for NAPI to complete can re-enable interrupts */
	ixgb_irq_disable(adapter);
	free_irq(adapter->pdev->irq, netdev);

	if (adapter->have_msi)
		pci_disable_msi(adapter->pdev);

	if (kill_watchdog)
		del_timer_sync(&adapter->watchdog_timer);

	adapter->link_speed = 0;
	adapter->link_duplex = 0;
	netif_carrier_off(netdev);
	netif_stop_queue(netdev);

	ixgb_reset(adapter);
	ixgb_clean_tx_ring(adapter);
	ixgb_clean_rx_ring(adapter);
}

void
ixgb_reset(struct ixgb_adapter *adapter)
{
	struct ixgb_hw *hw = &adapter->hw;

	ixgb_adapter_stop(hw);
	if (!ixgb_init_hw(hw))
		DPRINTK(PROBE, ERR, "ixgb_init_hw failed.\n");

	/* restore frame size information */
	IXGB_WRITE_REG(hw, MFS, hw->max_frame_size << IXGB_MFS_SHIFT);
	if (hw->max_frame_size >
	    IXGB_MAX_ENET_FRAME_SIZE_WITHOUT_FCS + ENET_FCS_LENGTH) {
		u32 ctrl0 = IXGB_READ_REG(hw, CTRL0);
		if (!(ctrl0 & IXGB_CTRL0_JFE)) {
			ctrl0 |= IXGB_CTRL0_JFE;
			IXGB_WRITE_REG(hw, CTRL0, ctrl0);
		}
	}
}

/**
 * ixgb_probe - Device Initialization Routine
 * @pdev: PCI device information struct
 * @ent: entry in ixgb_pci_tbl
 *
 * Returns 0 on success, negative on failure
 *
 * ixgb_probe initializes an adapter identified by a pci_dev structure.
 * The OS initialization, configuring of the adapter private structure,
 * and a hardware reset occur.
 **/

static int __devinit
ixgb_probe(struct pci_dev *pdev,
		const struct pci_device_id *ent)
{
	struct net_device *netdev = NULL;
	struct ixgb_adapter *adapter;
	static int cards_found = 0;
	int pci_using_dac;
	int i;
	int err;

	if ((err = pci_enable_device(pdev)))
		return err;

	if (!(err = pci_set_dma_mask(pdev, DMA_64BIT_MASK)) &&
	   !(err = pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK))) {
		pci_using_dac = 1;
	} else {
		if ((err = pci_set_dma_mask(pdev, DMA_32BIT_MASK)) ||
		   (err = pci_set_consistent_dma_mask(pdev, DMA_32BIT_MASK))) {
			printk(KERN_ERR
			 "ixgb: No usable DMA configuration, aborting\n");
			goto err_dma_mask;
		}
		pci_using_dac = 0;
	}

	if ((err = pci_request_regions(pdev, ixgb_driver_name)))
		goto err_request_regions;

	pci_set_master(pdev);

	netdev = alloc_etherdev(sizeof(struct ixgb_adapter));
	if (!netdev) {
		err = -ENOMEM;
		goto err_alloc_etherdev;
	}

	SET_NETDEV_DEV(netdev, &pdev->dev);

	pci_set_drvdata(pdev, netdev);
	adapter = netdev_priv(netdev);
	adapter->netdev = netdev;
	adapter->pdev = pdev;
	adapter->hw.back = adapter;
	adapter->msg_enable = netif_msg_init(debug, DEFAULT_DEBUG_LEVEL_SHIFT);

	adapter->hw.hw_addr = ioremap(pci_resource_start(pdev, BAR_0),
	                              pci_resource_len(pdev, BAR_0));
	if (!adapter->hw.hw_addr) {
		err = -EIO;
		goto err_ioremap;
	}

	for(i = BAR_1; i <= BAR_5; i++) {
		if (pci_resource_len(pdev, i) == 0)
			continue;
		if (pci_resource_flags(pdev, i) & IORESOURCE_IO) {
			adapter->hw.io_base = pci_resource_start(pdev, i);
			break;
		}
	}

	netdev->open = &ixgb_open;
	netdev->stop = &ixgb_close;
	netdev->hard_start_xmit = &ixgb_xmit_frame;
	netdev->get_stats = &ixgb_get_stats;
	netdev->set_multicast_list = &ixgb_set_multi;
	netdev->set_mac_address = &ixgb_set_mac;
	netdev->change_mtu = &ixgb_change_mtu;
	ixgb_set_ethtool_ops(netdev);
	netdev->tx_timeout = &ixgb_tx_timeout;
	netdev->watchdog_timeo = 5 * HZ;
#ifdef CONFIG_IXGB_NAPI
	netif_napi_add(netdev, &adapter->napi, ixgb_clean, 64);
#endif
	netdev->vlan_rx_register = ixgb_vlan_rx_register;
	netdev->vlan_rx_add_vid = ixgb_vlan_rx_add_vid;
	netdev->vlan_rx_kill_vid = ixgb_vlan_rx_kill_vid;
#ifdef CONFIG_NET_POLL_CONTROLLER
	netdev->poll_controller = ixgb_netpoll;
#endif

	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);

	adapter->bd_number = cards_found;
	adapter->link_speed = 0;
	adapter->link_duplex = 0;

	/* setup the private structure */

	if ((err = ixgb_sw_init(adapter)))
		goto err_sw_init;

	netdev->features = NETIF_F_SG |
			   NETIF_F_HW_CSUM |
			   NETIF_F_HW_VLAN_TX |
			   NETIF_F_HW_VLAN_RX |
			   NETIF_F_HW_VLAN_FILTER;
	netdev->features |= NETIF_F_TSO;

	if (pci_using_dac)
		netdev->features |= NETIF_F_HIGHDMA;

	/* make sure the EEPROM is good */

	if (!ixgb_validate_eeprom_checksum(&adapter->hw)) {
		DPRINTK(PROBE, ERR, "The EEPROM Checksum Is Not Valid\n");
		err = -EIO;
		goto err_eeprom;
	}

	ixgb_get_ee_mac_addr(&adapter->hw, netdev->dev_addr);
	memcpy(netdev->perm_addr, netdev->dev_addr, netdev->addr_len);

	if (!is_valid_ether_addr(netdev->perm_addr)) {
		DPRINTK(PROBE, ERR, "Invalid MAC Address\n");
		err = -EIO;
		goto err_eeprom;
	}

	adapter->part_num = ixgb_get_ee_pba_number(&adapter->hw);

	init_timer(&adapter->watchdog_timer);
	adapter->watchdog_timer.function = &ixgb_watchdog;
	adapter->watchdog_timer.data = (unsigned long)adapter;

	INIT_WORK(&adapter->tx_timeout_task, ixgb_tx_timeout_task);

	strcpy(netdev->name, "eth%d");
	if ((err = register_netdev(netdev)))
		goto err_register;

	/* we're going to reset, so assume we have no link for now */

	netif_carrier_off(netdev);
	netif_stop_queue(netdev);

	DPRINTK(PROBE, INFO, "Intel(R) PRO/10GbE Network Connection\n");
	ixgb_check_options(adapter);
	/* reset the hardware with the new settings */

	ixgb_reset(adapter);

	cards_found++;
	return 0;

err_register:
err_sw_init:
err_eeprom:
	iounmap(adapter->hw.hw_addr);
err_ioremap:
	free_netdev(netdev);
err_alloc_etherdev:
	pci_release_regions(pdev);
err_request_regions:
err_dma_mask:
	pci_disable_device(pdev);
	return err;
}

/**
 * ixgb_remove - Device Removal Routine
 * @pdev: PCI device information struct
 *
 * ixgb_remove is called by the PCI subsystem to alert the driver
 * that it should release a PCI device.  The could be caused by a
 * Hot-Plug event, or because the driver is going to be removed from
 * memory.
 **/

static void __devexit
ixgb_remove(struct pci_dev *pdev)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	flush_scheduled_work();

	unregister_netdev(netdev);

	iounmap(adapter->hw.hw_addr);
	pci_release_regions(pdev);

	free_netdev(netdev);
}

/**
 * ixgb_sw_init - Initialize general software structures (struct ixgb_adapter)
 * @adapter: board private structure to initialize
 *
 * ixgb_sw_init initializes the Adapter private data structure.
 * Fields are initialized based on PCI device information and
 * OS network device settings (MTU size).
 **/

static int __devinit
ixgb_sw_init(struct ixgb_adapter *adapter)
{
	struct ixgb_hw *hw = &adapter->hw;
	struct net_device *netdev = adapter->netdev;
	struct pci_dev *pdev = adapter->pdev;

	/* PCI config space info */

	hw->vendor_id = pdev->vendor;
	hw->device_id = pdev->device;
	hw->subsystem_vendor_id = pdev->subsystem_vendor;
	hw->subsystem_id = pdev->subsystem_device;

	hw->max_frame_size = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
	adapter->rx_buffer_len = hw->max_frame_size + 8; /* + 8 for errata */

	if ((hw->device_id == IXGB_DEVICE_ID_82597EX)
	   || (hw->device_id == IXGB_DEVICE_ID_82597EX_CX4)
	   || (hw->device_id == IXGB_DEVICE_ID_82597EX_LR)
	   || (hw->device_id == IXGB_DEVICE_ID_82597EX_SR))
			hw->mac_type = ixgb_82597;
	else {
		/* should never have loaded on this device */
		DPRINTK(PROBE, ERR, "unsupported device id\n");
	}

	/* enable flow control to be programmed */
	hw->fc.send_xon = 1;

	set_bit(__IXGB_DOWN, &adapter->flags);
	return 0;
}

/**
 * ixgb_open - Called when a network interface is made active
 * @netdev: network interface device structure
 *
 * Returns 0 on success, negative value on failure
 *
 * The open entry point is called when a network interface is made
 * active by the system (IFF_UP).  At this point all resources needed
 * for transmit and receive operations are allocated, the interrupt
 * handler is registered with the OS, the watchdog timer is started,
 * and the stack is notified that the interface is ready.
 **/

static int
ixgb_open(struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	int err;

	/* allocate transmit descriptors */

	if ((err = ixgb_setup_tx_resources(adapter)))
		goto err_setup_tx;

	/* allocate receive descriptors */

	if ((err = ixgb_setup_rx_resources(adapter)))
		goto err_setup_rx;

	if ((err = ixgb_up(adapter)))
		goto err_up;

	return 0;

err_up:
	ixgb_free_rx_resources(adapter);
err_setup_rx:
	ixgb_free_tx_resources(adapter);
err_setup_tx:
	ixgb_reset(adapter);

	return err;
}

/**
 * ixgb_close - Disables a network interface
 * @netdev: network interface device structure
 *
 * Returns 0, this is not allowed to fail
 *
 * The close entry point is called when an interface is de-activated
 * by the OS.  The hardware is still under the drivers control, but
 * needs to be disabled.  A global MAC reset is issued to stop the
 * hardware, and all transmit and receive resources are freed.
 **/

static int
ixgb_close(struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	ixgb_down(adapter, true);

	ixgb_free_tx_resources(adapter);
	ixgb_free_rx_resources(adapter);

	return 0;
}

/**
 * ixgb_setup_tx_resources - allocate Tx resources (Descriptors)
 * @adapter: board private structure
 *
 * Return 0 on success, negative on failure
 **/

int
ixgb_setup_tx_resources(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *txdr = &adapter->tx_ring;
	struct pci_dev *pdev = adapter->pdev;
	int size;

	size = sizeof(struct ixgb_buffer) * txdr->count;
	txdr->buffer_info = vmalloc(size);
	if (!txdr->buffer_info) {
		DPRINTK(PROBE, ERR,
		 "Unable to allocate transmit descriptor ring memory\n");
		return -ENOMEM;
	}
	memset(txdr->buffer_info, 0, size);

	/* round up to nearest 4K */

	txdr->size = txdr->count * sizeof(struct ixgb_tx_desc);
	txdr->size = ALIGN(txdr->size, 4096);

	txdr->desc = pci_alloc_consistent(pdev, txdr->size, &txdr->dma);
	if (!txdr->desc) {
		vfree(txdr->buffer_info);
		DPRINTK(PROBE, ERR,
		 "Unable to allocate transmit descriptor memory\n");
		return -ENOMEM;
	}
	memset(txdr->desc, 0, txdr->size);

	txdr->next_to_use = 0;
	txdr->next_to_clean = 0;

	return 0;
}

/**
 * ixgb_configure_tx - Configure 82597 Transmit Unit after Reset.
 * @adapter: board private structure
 *
 * Configure the Tx unit of the MAC after a reset.
 **/

static void
ixgb_configure_tx(struct ixgb_adapter *adapter)
{
	u64 tdba = adapter->tx_ring.dma;
	u32 tdlen = adapter->tx_ring.count * sizeof(struct ixgb_tx_desc);
	u32 tctl;
	struct ixgb_hw *hw = &adapter->hw;

	/* Setup the Base and Length of the Tx Descriptor Ring 
	 * tx_ring.dma can be either a 32 or 64 bit value 
	 */

	IXGB_WRITE_REG(hw, TDBAL, (tdba & 0x00000000ffffffffULL));
	IXGB_WRITE_REG(hw, TDBAH, (tdba >> 32));

	IXGB_WRITE_REG(hw, TDLEN, tdlen);

	/* Setup the HW Tx Head and Tail descriptor pointers */

	IXGB_WRITE_REG(hw, TDH, 0);
	IXGB_WRITE_REG(hw, TDT, 0);

	/* don't set up txdctl, it induces performance problems if configured
	 * incorrectly */
	/* Set the Tx Interrupt Delay register */

	IXGB_WRITE_REG(hw, TIDV, adapter->tx_int_delay);

	/* Program the Transmit Control Register */

	tctl = IXGB_TCTL_TCE | IXGB_TCTL_TXEN | IXGB_TCTL_TPDE;
	IXGB_WRITE_REG(hw, TCTL, tctl);

	/* Setup Transmit Descriptor Settings for this adapter */
	adapter->tx_cmd_type =
		IXGB_TX_DESC_TYPE 
		| (adapter->tx_int_delay_enable ? IXGB_TX_DESC_CMD_IDE : 0);
}

/**
 * ixgb_setup_rx_resources - allocate Rx resources (Descriptors)
 * @adapter: board private structure
 *
 * Returns 0 on success, negative on failure
 **/

int
ixgb_setup_rx_resources(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *rxdr = &adapter->rx_ring;
	struct pci_dev *pdev = adapter->pdev;
	int size;

	size = sizeof(struct ixgb_buffer) * rxdr->count;
	rxdr->buffer_info = vmalloc(size);
	if (!rxdr->buffer_info) {
		DPRINTK(PROBE, ERR,
		 "Unable to allocate receive descriptor ring\n");
		return -ENOMEM;
	}
	memset(rxdr->buffer_info, 0, size);

	/* Round up to nearest 4K */

	rxdr->size = rxdr->count * sizeof(struct ixgb_rx_desc);
	rxdr->size = ALIGN(rxdr->size, 4096);

	rxdr->desc = pci_alloc_consistent(pdev, rxdr->size, &rxdr->dma);

	if (!rxdr->desc) {
		vfree(rxdr->buffer_info);
		DPRINTK(PROBE, ERR,
		 "Unable to allocate receive descriptors\n");
		return -ENOMEM;
	}
	memset(rxdr->desc, 0, rxdr->size);

	rxdr->next_to_clean = 0;
	rxdr->next_to_use = 0;

	return 0;
}

/**
 * ixgb_setup_rctl - configure the receive control register
 * @adapter: Board private structure
 **/

static void
ixgb_setup_rctl(struct ixgb_adapter *adapter)
{
	u32 rctl;

	rctl = IXGB_READ_REG(&adapter->hw, RCTL);

	rctl &= ~(3 << IXGB_RCTL_MO_SHIFT);

	rctl |=
		IXGB_RCTL_BAM | IXGB_RCTL_RDMTS_1_2 | 
		IXGB_RCTL_RXEN | IXGB_RCTL_CFF | 
		(adapter->hw.mc_filter_type << IXGB_RCTL_MO_SHIFT);

	rctl |= IXGB_RCTL_SECRC;

	if (adapter->rx_buffer_len <= IXGB_RXBUFFER_2048)
		rctl |= IXGB_RCTL_BSIZE_2048;
	else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_4096)
		rctl |= IXGB_RCTL_BSIZE_4096;
	else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_8192)
		rctl |= IXGB_RCTL_BSIZE_8192;
	else if (adapter->rx_buffer_len <= IXGB_RXBUFFER_16384)
		rctl |= IXGB_RCTL_BSIZE_16384;

	IXGB_WRITE_REG(&adapter->hw, RCTL, rctl);
}

/**
 * ixgb_configure_rx - Configure 82597 Receive Unit after Reset.
 * @adapter: board private structure
 *
 * Configure the Rx unit of the MAC after a reset.
 **/

static void
ixgb_configure_rx(struct ixgb_adapter *adapter)
{
	u64 rdba = adapter->rx_ring.dma;
	u32 rdlen = adapter->rx_ring.count * sizeof(struct ixgb_rx_desc);
	struct ixgb_hw *hw = &adapter->hw;
	u32 rctl;
	u32 rxcsum;

	/* make sure receives are disabled while setting up the descriptors */

	rctl = IXGB_READ_REG(hw, RCTL);
	IXGB_WRITE_REG(hw, RCTL, rctl & ~IXGB_RCTL_RXEN);

	/* set the Receive Delay Timer Register */

	IXGB_WRITE_REG(hw, RDTR, adapter->rx_int_delay);

	/* Setup the Base and Length of the Rx Descriptor Ring */

	IXGB_WRITE_REG(hw, RDBAL, (rdba & 0x00000000ffffffffULL));
	IXGB_WRITE_REG(hw, RDBAH, (rdba >> 32));

	IXGB_WRITE_REG(hw, RDLEN, rdlen);

	/* Setup the HW Rx Head and Tail Descriptor Pointers */
	IXGB_WRITE_REG(hw, RDH, 0);
	IXGB_WRITE_REG(hw, RDT, 0);

	/* due to the hardware errata with RXDCTL, we are unable to use any of
	 * the performance enhancing features of it without causing other
	 * subtle bugs, some of the bugs could include receive length
	 * corruption at high data rates (WTHRESH > 0) and/or receive
	 * descriptor ring irregularites (particularly in hardware cache) */
	IXGB_WRITE_REG(hw, RXDCTL, 0);

	/* Enable Receive Checksum Offload for TCP and UDP */
	if (adapter->rx_csum) {
		rxcsum = IXGB_READ_REG(hw, RXCSUM);
		rxcsum |= IXGB_RXCSUM_TUOFL;
		IXGB_WRITE_REG(hw, RXCSUM, rxcsum);
	}

	/* Enable Receives */

	IXGB_WRITE_REG(hw, RCTL, rctl);
}

/**
 * ixgb_free_tx_resources - Free Tx Resources
 * @adapter: board private structure
 *
 * Free all transmit software resources
 **/

void
ixgb_free_tx_resources(struct ixgb_adapter *adapter)
{
	struct pci_dev *pdev = adapter->pdev;

	ixgb_clean_tx_ring(adapter);

	vfree(adapter->tx_ring.buffer_info);
	adapter->tx_ring.buffer_info = NULL;

	pci_free_consistent(pdev, adapter->tx_ring.size,
			    adapter->tx_ring.desc, adapter->tx_ring.dma);

	adapter->tx_ring.desc = NULL;
}

static void
ixgb_unmap_and_free_tx_resource(struct ixgb_adapter *adapter,
					struct ixgb_buffer *buffer_info)
{
	struct pci_dev *pdev = adapter->pdev;

	if (buffer_info->dma)
		pci_unmap_page(pdev, buffer_info->dma, buffer_info->length,
		               PCI_DMA_TODEVICE);

	if (buffer_info->skb)
		dev_kfree_skb_any(buffer_info->skb);

	buffer_info->skb = NULL;
	buffer_info->dma = 0;
	buffer_info->time_stamp = 0;
	/* these fields must always be initialized in tx
	 * buffer_info->length = 0;
	 * buffer_info->next_to_watch = 0; */
}

/**
 * ixgb_clean_tx_ring - Free Tx Buffers
 * @adapter: board private structure
 **/

static void
ixgb_clean_tx_ring(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
	struct ixgb_buffer *buffer_info;
	unsigned long size;
	unsigned int i;

	/* Free all the Tx ring sk_buffs */

	for(i = 0; i < tx_ring->count; i++) {
		buffer_info = &tx_ring->buffer_info[i];
		ixgb_unmap_and_free_tx_resource(adapter, buffer_info);
	}

	size = sizeof(struct ixgb_buffer) * tx_ring->count;
	memset(tx_ring->buffer_info, 0, size);

	/* Zero out the descriptor ring */

	memset(tx_ring->desc, 0, tx_ring->size);

	tx_ring->next_to_use = 0;
	tx_ring->next_to_clean = 0;

	IXGB_WRITE_REG(&adapter->hw, TDH, 0);
	IXGB_WRITE_REG(&adapter->hw, TDT, 0);
}

/**
 * ixgb_free_rx_resources - Free Rx Resources
 * @adapter: board private structure
 *
 * Free all receive software resources
 **/

void
ixgb_free_rx_resources(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
	struct pci_dev *pdev = adapter->pdev;

	ixgb_clean_rx_ring(adapter);

	vfree(rx_ring->buffer_info);
	rx_ring->buffer_info = NULL;

	pci_free_consistent(pdev, rx_ring->size, rx_ring->desc, rx_ring->dma);

	rx_ring->desc = NULL;
}

/**
 * ixgb_clean_rx_ring - Free Rx Buffers
 * @adapter: board private structure
 **/

static void
ixgb_clean_rx_ring(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
	struct ixgb_buffer *buffer_info;
	struct pci_dev *pdev = adapter->pdev;
	unsigned long size;
	unsigned int i;

	/* Free all the Rx ring sk_buffs */

	for(i = 0; i < rx_ring->count; i++) {
		buffer_info = &rx_ring->buffer_info[i];
		if (buffer_info->skb) {

			pci_unmap_single(pdev,
					 buffer_info->dma,
					 buffer_info->length,
					 PCI_DMA_FROMDEVICE);

			dev_kfree_skb(buffer_info->skb);

			buffer_info->skb = NULL;
		}
	}

	size = sizeof(struct ixgb_buffer) * rx_ring->count;
	memset(rx_ring->buffer_info, 0, size);

	/* Zero out the descriptor ring */

	memset(rx_ring->desc, 0, rx_ring->size);

	rx_ring->next_to_clean = 0;
	rx_ring->next_to_use = 0;

	IXGB_WRITE_REG(&adapter->hw, RDH, 0);
	IXGB_WRITE_REG(&adapter->hw, RDT, 0);
}

/**
 * ixgb_set_mac - Change the Ethernet Address of the NIC
 * @netdev: network interface device structure
 * @p: pointer to an address structure
 *
 * Returns 0 on success, negative on failure
 **/

static int
ixgb_set_mac(struct net_device *netdev, void *p)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	struct sockaddr *addr = p;

	if (!is_valid_ether_addr(addr->sa_data))
		return -EADDRNOTAVAIL;

	memcpy(netdev->dev_addr, addr->sa_data, netdev->addr_len);

	ixgb_rar_set(&adapter->hw, addr->sa_data, 0);

	return 0;
}

/**
 * ixgb_set_multi - Multicast and Promiscuous mode set
 * @netdev: network interface device structure
 *
 * The set_multi entry point is called whenever the multicast address
 * list or the network interface flags are updated.  This routine is
 * responsible for configuring the hardware for proper multicast,
 * promiscuous mode, and all-multi behavior.
 **/

static void
ixgb_set_multi(struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	struct ixgb_hw *hw = &adapter->hw;
	struct dev_mc_list *mc_ptr;
	u32 rctl;
	int i;

	/* Check for Promiscuous and All Multicast modes */

	rctl = IXGB_READ_REG(hw, RCTL);

	if (netdev->flags & IFF_PROMISC) {
		rctl |= (IXGB_RCTL_UPE | IXGB_RCTL_MPE);
	} else if (netdev->flags & IFF_ALLMULTI) {
		rctl |= IXGB_RCTL_MPE;
		rctl &= ~IXGB_RCTL_UPE;
	} else {
		rctl &= ~(IXGB_RCTL_UPE | IXGB_RCTL_MPE);
	}

	if (netdev->mc_count > IXGB_MAX_NUM_MULTICAST_ADDRESSES) {
		rctl |= IXGB_RCTL_MPE;
		IXGB_WRITE_REG(hw, RCTL, rctl);
	} else {
		u8 mta[IXGB_MAX_NUM_MULTICAST_ADDRESSES *
			    IXGB_ETH_LENGTH_OF_ADDRESS];

		IXGB_WRITE_REG(hw, RCTL, rctl);

		for(i = 0, mc_ptr = netdev->mc_list; mc_ptr;
			i++, mc_ptr = mc_ptr->next)
			memcpy(&mta[i * IXGB_ETH_LENGTH_OF_ADDRESS],
				   mc_ptr->dmi_addr, IXGB_ETH_LENGTH_OF_ADDRESS);

		ixgb_mc_addr_list_update(hw, mta, netdev->mc_count, 0);
	}
}

/**
 * ixgb_watchdog - Timer Call-back
 * @data: pointer to netdev cast into an unsigned long
 **/

static void
ixgb_watchdog(unsigned long data)
{
	struct ixgb_adapter *adapter = (struct ixgb_adapter *)data;
	struct net_device *netdev = adapter->netdev;
	struct ixgb_desc_ring *txdr = &adapter->tx_ring;

	ixgb_check_for_link(&adapter->hw);

	if (ixgb_check_for_bad_link(&adapter->hw)) {
		/* force the reset path */
		netif_stop_queue(netdev);
	}

	if (adapter->hw.link_up) {
		if (!netif_carrier_ok(netdev)) {
			DPRINTK(LINK, INFO,
			        "NIC Link is Up 10000 Mbps Full Duplex\n");
			adapter->link_speed = 10000;
			adapter->link_duplex = FULL_DUPLEX;
			netif_carrier_on(netdev);
			netif_wake_queue(netdev);
		}
	} else {
		if (netif_carrier_ok(netdev)) {
			adapter->link_speed = 0;
			adapter->link_duplex = 0;
			DPRINTK(LINK, INFO, "NIC Link is Down\n");
			netif_carrier_off(netdev);
			netif_stop_queue(netdev);

		}
	}

	ixgb_update_stats(adapter);

	if (!netif_carrier_ok(netdev)) {
		if (IXGB_DESC_UNUSED(txdr) + 1 < txdr->count) {
			/* We've lost link, so the controller stops DMA,
			 * but we've got queued Tx work that's never going
			 * to get done, so reset controller to flush Tx.
			 * (Do the reset outside of interrupt context). */
			schedule_work(&adapter->tx_timeout_task);
		}
	}

	/* Force detection of hung controller every watchdog period */
	adapter->detect_tx_hung = true;

	/* generate an interrupt to force clean up of any stragglers */
	IXGB_WRITE_REG(&adapter->hw, ICS, IXGB_INT_TXDW);

	/* Reset the timer */
	mod_timer(&adapter->watchdog_timer, jiffies + 2 * HZ);
}

#define IXGB_TX_FLAGS_CSUM		0x00000001
#define IXGB_TX_FLAGS_VLAN		0x00000002
#define IXGB_TX_FLAGS_TSO		0x00000004

static int
ixgb_tso(struct ixgb_adapter *adapter, struct sk_buff *skb)
{
	struct ixgb_context_desc *context_desc;
	unsigned int i;
	u8 ipcss, ipcso, tucss, tucso, hdr_len;
	u16 ipcse, tucse, mss;
	int err;

	if (likely(skb_is_gso(skb))) {
		struct ixgb_buffer *buffer_info;
		struct iphdr *iph;

		if (skb_header_cloned(skb)) {
			err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
			if (err)
				return err;
		}

		hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
		mss = skb_shinfo(skb)->gso_size;
		iph = ip_hdr(skb);
		iph->tot_len = 0;
		iph->check = 0;
		tcp_hdr(skb)->check = ~csum_tcpudp_magic(iph->saddr,
							 iph->daddr, 0,
							 IPPROTO_TCP, 0);
		ipcss = skb_network_offset(skb);
		ipcso = (void *)&(iph->check) - (void *)skb->data;
		ipcse = skb_transport_offset(skb) - 1;
		tucss = skb_transport_offset(skb);
		tucso = (void *)&(tcp_hdr(skb)->check) - (void *)skb->data;
		tucse = 0;

		i = adapter->tx_ring.next_to_use;
		context_desc = IXGB_CONTEXT_DESC(adapter->tx_ring, i);
		buffer_info = &adapter->tx_ring.buffer_info[i];
		WARN_ON(buffer_info->dma != 0);

		context_desc->ipcss = ipcss;
		context_desc->ipcso = ipcso;
		context_desc->ipcse = cpu_to_le16(ipcse);
		context_desc->tucss = tucss;
		context_desc->tucso = tucso;
		context_desc->tucse = cpu_to_le16(tucse);
		context_desc->mss = cpu_to_le16(mss);
		context_desc->hdr_len = hdr_len;
		context_desc->status = 0;
		context_desc->cmd_type_len = cpu_to_le32(
						  IXGB_CONTEXT_DESC_TYPE 
						| IXGB_CONTEXT_DESC_CMD_TSE
						| IXGB_CONTEXT_DESC_CMD_IP
						| IXGB_CONTEXT_DESC_CMD_TCP
						| IXGB_CONTEXT_DESC_CMD_IDE
						| (skb->len - (hdr_len)));


		if (++i == adapter->tx_ring.count) i = 0;
		adapter->tx_ring.next_to_use = i;

		return 1;
	}

	return 0;
}

static bool
ixgb_tx_csum(struct ixgb_adapter *adapter, struct sk_buff *skb)
{
	struct ixgb_context_desc *context_desc;
	unsigned int i;
	u8 css, cso;

	if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
		struct ixgb_buffer *buffer_info;
		css = skb_transport_offset(skb);
		cso = css + skb->csum_offset;

		i = adapter->tx_ring.next_to_use;
		context_desc = IXGB_CONTEXT_DESC(adapter->tx_ring, i);
		buffer_info = &adapter->tx_ring.buffer_info[i];
		WARN_ON(buffer_info->dma != 0);

		context_desc->tucss = css;
		context_desc->tucso = cso;
		context_desc->tucse = 0;
		/* zero out any previously existing data in one instruction */
		*(u32 *)&(context_desc->ipcss) = 0;
		context_desc->status = 0;
		context_desc->hdr_len = 0;
		context_desc->mss = 0;
		context_desc->cmd_type_len =
			cpu_to_le32(IXGB_CONTEXT_DESC_TYPE
				    | IXGB_TX_DESC_CMD_IDE);

		if (++i == adapter->tx_ring.count) i = 0;
		adapter->tx_ring.next_to_use = i;

		return true;
	}

	return false;
}

#define IXGB_MAX_TXD_PWR	14
#define IXGB_MAX_DATA_PER_TXD	(1<<IXGB_MAX_TXD_PWR)

static int
ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb,
	    unsigned int first)
{
	struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
	struct ixgb_buffer *buffer_info;
	int len = skb->len;
	unsigned int offset = 0, size, count = 0, i;
	unsigned int mss = skb_shinfo(skb)->gso_size;

	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
	unsigned int f;

	len -= skb->data_len;

	i = tx_ring->next_to_use;

	while (len) {
		buffer_info = &tx_ring->buffer_info[i];
		size = min(len, IXGB_MAX_DATA_PER_TXD);
		/* Workaround for premature desc write-backs
		 * in TSO mode.  Append 4-byte sentinel desc */
		if (unlikely(mss && !nr_frags && size == len && size > 8))
			size -= 4;

		buffer_info->length = size;
		WARN_ON(buffer_info->dma != 0);
		buffer_info->time_stamp = jiffies;
		buffer_info->dma =
			pci_map_single(adapter->pdev,
				skb->data + offset,
				size,
				PCI_DMA_TODEVICE);
		buffer_info->next_to_watch = 0;

		len -= size;
		offset += size;
		count++;
		if (++i == tx_ring->count) i = 0;
	}

	for(f = 0; f < nr_frags; f++) {
		struct skb_frag_struct *frag;

		frag = &skb_shinfo(skb)->frags[f];
		len = frag->size;
		offset = 0;

		while (len) {
			buffer_info = &tx_ring->buffer_info[i];
			size = min(len, IXGB_MAX_DATA_PER_TXD);

			/* Workaround for premature desc write-backs
			 * in TSO mode.  Append 4-byte sentinel desc */
			if (unlikely(mss && (f == (nr_frags - 1))
				     && size == len && size > 8))
				size -= 4;

			buffer_info->length = size;
			buffer_info->time_stamp = jiffies;
			buffer_info->dma =
				pci_map_page(adapter->pdev,
					frag->page,
					frag->page_offset + offset,
					size,
					PCI_DMA_TODEVICE);
			buffer_info->next_to_watch = 0;

			len -= size;
			offset += size;
			count++;
			if (++i == tx_ring->count) i = 0;
		}
	}
	i = (i == 0) ? tx_ring->count - 1 : i - 1;
	tx_ring->buffer_info[i].skb = skb;
	tx_ring->buffer_info[first].next_to_watch = i;

	return count;
}

static void
ixgb_tx_queue(struct ixgb_adapter *adapter, int count, int vlan_id,int tx_flags)
{
	struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
	struct ixgb_tx_desc *tx_desc = NULL;
	struct ixgb_buffer *buffer_info;
	u32 cmd_type_len = adapter->tx_cmd_type;
	u8 status = 0;
	u8 popts = 0;
	unsigned int i;

	if (tx_flags & IXGB_TX_FLAGS_TSO) {
		cmd_type_len |= IXGB_TX_DESC_CMD_TSE;
		popts |= (IXGB_TX_DESC_POPTS_IXSM | IXGB_TX_DESC_POPTS_TXSM);
	}

	if (tx_flags & IXGB_TX_FLAGS_CSUM)
		popts |= IXGB_TX_DESC_POPTS_TXSM;

	if (tx_flags & IXGB_TX_FLAGS_VLAN)
		cmd_type_len |= IXGB_TX_DESC_CMD_VLE;

	i = tx_ring->next_to_use;

	while (count--) {
		buffer_info = &tx_ring->buffer_info[i];
		tx_desc = IXGB_TX_DESC(*tx_ring, i);
		tx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
		tx_desc->cmd_type_len =
			cpu_to_le32(cmd_type_len | buffer_info->length);
		tx_desc->status = status;
		tx_desc->popts = popts;
		tx_desc->vlan = cpu_to_le16(vlan_id);

		if (++i == tx_ring->count) i = 0;
	}

	tx_desc->cmd_type_len |= cpu_to_le32(IXGB_TX_DESC_CMD_EOP 
				| IXGB_TX_DESC_CMD_RS );

	/* Force memory writes to complete before letting h/w
	 * know there are new descriptors to fetch.  (Only
	 * applicable for weak-ordered memory model archs,
	 * such as IA-64). */
	wmb();

	tx_ring->next_to_use = i;
	IXGB_WRITE_REG(&adapter->hw, TDT, i);
}

static int __ixgb_maybe_stop_tx(struct net_device *netdev, int size)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;

	netif_stop_queue(netdev);
	/* Herbert's original patch had:
	 *  smp_mb__after_netif_stop_queue();
	 * but since that doesn't exist yet, just open code it. */
	smp_mb();

	/* We need to check again in a case another CPU has just
	 * made room available. */
	if (likely(IXGB_DESC_UNUSED(tx_ring) < size))
		return -EBUSY;

	/* A reprieve! */
	netif_start_queue(netdev);
	++adapter->restart_queue;
	return 0;
}

static int ixgb_maybe_stop_tx(struct net_device *netdev,
                              struct ixgb_desc_ring *tx_ring, int size)
{
	if (likely(IXGB_DESC_UNUSED(tx_ring) >= size))
		return 0;
	return __ixgb_maybe_stop_tx(netdev, size);
}


/* Tx Descriptors needed, worst case */
#define TXD_USE_COUNT(S) (((S) >> IXGB_MAX_TXD_PWR) + \
			 (((S) & (IXGB_MAX_DATA_PER_TXD - 1)) ? 1 : 0))
#define DESC_NEEDED TXD_USE_COUNT(IXGB_MAX_DATA_PER_TXD) /* skb->date */ + \
	MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1 /* for context */ \
	+ 1 /* one more needed for sentinel TSO workaround */

static int
ixgb_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	unsigned int first;
	unsigned int tx_flags = 0;
	int vlan_id = 0;
	int tso;

	if (test_bit(__IXGB_DOWN, &adapter->flags)) {
		dev_kfree_skb(skb);
		return NETDEV_TX_OK;
	}

	if (skb->len <= 0) {
		dev_kfree_skb_any(skb);
		return 0;
	}

	if (unlikely(ixgb_maybe_stop_tx(netdev, &adapter->tx_ring,
                     DESC_NEEDED)))
		return NETDEV_TX_BUSY;

	if (adapter->vlgrp && vlan_tx_tag_present(skb)) {
		tx_flags |= IXGB_TX_FLAGS_VLAN;
		vlan_id = vlan_tx_tag_get(skb);
	}

	first = adapter->tx_ring.next_to_use;
	
	tso = ixgb_tso(adapter, skb);
	if (tso < 0) {
		dev_kfree_skb_any(skb);
		return NETDEV_TX_OK;
	}

	if (likely(tso))
		tx_flags |= IXGB_TX_FLAGS_TSO;
	else if (ixgb_tx_csum(adapter, skb))
		tx_flags |= IXGB_TX_FLAGS_CSUM;

	ixgb_tx_queue(adapter, ixgb_tx_map(adapter, skb, first), vlan_id,
			tx_flags);

	netdev->trans_start = jiffies;

	/* Make sure there is space in the ring for the next send. */
	ixgb_maybe_stop_tx(netdev, &adapter->tx_ring, DESC_NEEDED);

	return NETDEV_TX_OK;
}

/**
 * ixgb_tx_timeout - Respond to a Tx Hang
 * @netdev: network interface device structure
 **/

static void
ixgb_tx_timeout(struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	/* Do the reset outside of interrupt context */
	schedule_work(&adapter->tx_timeout_task);
}

static void
ixgb_tx_timeout_task(struct work_struct *work)
{
	struct ixgb_adapter *adapter =
		container_of(work, struct ixgb_adapter, tx_timeout_task);

	adapter->tx_timeout_count++;
	ixgb_down(adapter, true);
	ixgb_up(adapter);
}

/**
 * ixgb_get_stats - Get System Network Statistics
 * @netdev: network interface device structure
 *
 * Returns the address of the device statistics structure.
 * The statistics are actually updated from the timer callback.
 **/

static struct net_device_stats *
ixgb_get_stats(struct net_device *netdev)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	return &adapter->net_stats;
}

/**
 * ixgb_change_mtu - Change the Maximum Transfer Unit
 * @netdev: network interface device structure
 * @new_mtu: new value for maximum frame size
 *
 * Returns 0 on success, negative on failure
 **/

static int
ixgb_change_mtu(struct net_device *netdev, int new_mtu)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	int max_frame = new_mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
	int old_max_frame = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;

	/* MTU < 68 is an error for IPv4 traffic, just don't allow it */
	if ((new_mtu < 68) ||
	    (max_frame > IXGB_MAX_JUMBO_FRAME_SIZE + ENET_FCS_LENGTH)) {
		DPRINTK(PROBE, ERR, "Invalid MTU setting %d\n", new_mtu);
		return -EINVAL;
	}

	if (old_max_frame == max_frame)
		return 0;

	if (netif_running(netdev))
		ixgb_down(adapter, true);

	adapter->rx_buffer_len = max_frame + 8; /* + 8 for errata */

	netdev->mtu = new_mtu;

	if (netif_running(netdev))
		ixgb_up(adapter);

	return 0;
}

/**
 * ixgb_update_stats - Update the board statistics counters.
 * @adapter: board private structure
 **/

void
ixgb_update_stats(struct ixgb_adapter *adapter)
{
	struct net_device *netdev = adapter->netdev;
	struct pci_dev *pdev = adapter->pdev;

	/* Prevent stats update while adapter is being reset */
	if (pci_channel_offline(pdev))
		return;

	if ((netdev->flags & IFF_PROMISC) || (netdev->flags & IFF_ALLMULTI) ||
	   (netdev->mc_count > IXGB_MAX_NUM_MULTICAST_ADDRESSES)) {
		u64 multi = IXGB_READ_REG(&adapter->hw, MPRCL);
		u32 bcast_l = IXGB_READ_REG(&adapter->hw, BPRCL);
		u32 bcast_h = IXGB_READ_REG(&adapter->hw, BPRCH);
		u64 bcast = ((u64)bcast_h << 32) | bcast_l; 

		multi |= ((u64)IXGB_READ_REG(&adapter->hw, MPRCH) << 32);
		/* fix up multicast stats by removing broadcasts */
		if (multi >= bcast)
			multi -= bcast;
		
		adapter->stats.mprcl += (multi & 0xFFFFFFFF);
		adapter->stats.mprch += (multi >> 32);
		adapter->stats.bprcl += bcast_l; 
		adapter->stats.bprch += bcast_h;
	} else {
		adapter->stats.mprcl += IXGB_READ_REG(&adapter->hw, MPRCL);
		adapter->stats.mprch += IXGB_READ_REG(&adapter->hw, MPRCH);
		adapter->stats.bprcl += IXGB_READ_REG(&adapter->hw, BPRCL);
		adapter->stats.bprch += IXGB_READ_REG(&adapter->hw, BPRCH);
	}
	adapter->stats.tprl += IXGB_READ_REG(&adapter->hw, TPRL);
	adapter->stats.tprh += IXGB_READ_REG(&adapter->hw, TPRH);
	adapter->stats.gprcl += IXGB_READ_REG(&adapter->hw, GPRCL);
	adapter->stats.gprch += IXGB_READ_REG(&adapter->hw, GPRCH);
	adapter->stats.uprcl += IXGB_READ_REG(&adapter->hw, UPRCL);
	adapter->stats.uprch += IXGB_READ_REG(&adapter->hw, UPRCH);
	adapter->stats.vprcl += IXGB_READ_REG(&adapter->hw, VPRCL);
	adapter->stats.vprch += IXGB_READ_REG(&adapter->hw, VPRCH);
	adapter->stats.jprcl += IXGB_READ_REG(&adapter->hw, JPRCL);
	adapter->stats.jprch += IXGB_READ_REG(&adapter->hw, JPRCH);
	adapter->stats.gorcl += IXGB_READ_REG(&adapter->hw, GORCL);
	adapter->stats.gorch += IXGB_READ_REG(&adapter->hw, GORCH);
	adapter->stats.torl += IXGB_READ_REG(&adapter->hw, TORL);
	adapter->stats.torh += IXGB_READ_REG(&adapter->hw, TORH);
	adapter->stats.rnbc += IXGB_READ_REG(&adapter->hw, RNBC);
	adapter->stats.ruc += IXGB_READ_REG(&adapter->hw, RUC);
	adapter->stats.roc += IXGB_READ_REG(&adapter->hw, ROC);
	adapter->stats.rlec += IXGB_READ_REG(&adapter->hw, RLEC);
	adapter->stats.crcerrs += IXGB_READ_REG(&adapter->hw, CRCERRS);
	adapter->stats.icbc += IXGB_READ_REG(&adapter->hw, ICBC);
	adapter->stats.ecbc += IXGB_READ_REG(&adapter->hw, ECBC);
	adapter->stats.mpc += IXGB_READ_REG(&adapter->hw, MPC);
	adapter->stats.tptl += IXGB_READ_REG(&adapter->hw, TPTL);
	adapter->stats.tpth += IXGB_READ_REG(&adapter->hw, TPTH);
	adapter->stats.gptcl += IXGB_READ_REG(&adapter->hw, GPTCL);
	adapter->stats.gptch += IXGB_READ_REG(&adapter->hw, GPTCH);
	adapter->stats.bptcl += IXGB_READ_REG(&adapter->hw, BPTCL);
	adapter->stats.bptch += IXGB_READ_REG(&adapter->hw, BPTCH);
	adapter->stats.mptcl += IXGB_READ_REG(&adapter->hw, MPTCL);
	adapter->stats.mptch += IXGB_READ_REG(&adapter->hw, MPTCH);
	adapter->stats.uptcl += IXGB_READ_REG(&adapter->hw, UPTCL);
	adapter->stats.uptch += IXGB_READ_REG(&adapter->hw, UPTCH);
	adapter->stats.vptcl += IXGB_READ_REG(&adapter->hw, VPTCL);
	adapter->stats.vptch += IXGB_READ_REG(&adapter->hw, VPTCH);
	adapter->stats.jptcl += IXGB_READ_REG(&adapter->hw, JPTCL);
	adapter->stats.jptch += IXGB_READ_REG(&adapter->hw, JPTCH);
	adapter->stats.gotcl += IXGB_READ_REG(&adapter->hw, GOTCL);
	adapter->stats.gotch += IXGB_READ_REG(&adapter->hw, GOTCH);
	adapter->stats.totl += IXGB_READ_REG(&adapter->hw, TOTL);
	adapter->stats.toth += IXGB_READ_REG(&adapter->hw, TOTH);
	adapter->stats.dc += IXGB_READ_REG(&adapter->hw, DC);
	adapter->stats.plt64c += IXGB_READ_REG(&adapter->hw, PLT64C);
	adapter->stats.tsctc += IXGB_READ_REG(&adapter->hw, TSCTC);
	adapter->stats.tsctfc += IXGB_READ_REG(&adapter->hw, TSCTFC);
	adapter->stats.ibic += IXGB_READ_REG(&adapter->hw, IBIC);
	adapter->stats.rfc += IXGB_READ_REG(&adapter->hw, RFC);
	adapter->stats.lfc += IXGB_READ_REG(&adapter->hw, LFC);
	adapter->stats.pfrc += IXGB_READ_REG(&adapter->hw, PFRC);
	adapter->stats.pftc += IXGB_READ_REG(&adapter->hw, PFTC);
	adapter->stats.mcfrc += IXGB_READ_REG(&adapter->hw, MCFRC);
	adapter->stats.mcftc += IXGB_READ_REG(&adapter->hw, MCFTC);
	adapter->stats.xonrxc += IXGB_READ_REG(&adapter->hw, XONRXC);
	adapter->stats.xontxc += IXGB_READ_REG(&adapter->hw, XONTXC);
	adapter->stats.xoffrxc += IXGB_READ_REG(&adapter->hw, XOFFRXC);
	adapter->stats.xofftxc += IXGB_READ_REG(&adapter->hw, XOFFTXC);
	adapter->stats.rjc += IXGB_READ_REG(&adapter->hw, RJC);

	/* Fill out the OS statistics structure */

	adapter->net_stats.rx_packets = adapter->stats.gprcl;
	adapter->net_stats.tx_packets = adapter->stats.gptcl;
	adapter->net_stats.rx_bytes = adapter->stats.gorcl;
	adapter->net_stats.tx_bytes = adapter->stats.gotcl;
	adapter->net_stats.multicast = adapter->stats.mprcl;
	adapter->net_stats.collisions = 0;

	/* ignore RLEC as it reports errors for padded (<64bytes) frames
	 * with a length in the type/len field */
	adapter->net_stats.rx_errors =
	    /* adapter->stats.rnbc + */ adapter->stats.crcerrs +
	    adapter->stats.ruc +
	    adapter->stats.roc /*+ adapter->stats.rlec */  +
	    adapter->stats.icbc +
	    adapter->stats.ecbc + adapter->stats.mpc;

	/* see above
	 * adapter->net_stats.rx_length_errors = adapter->stats.rlec;
	 */

	adapter->net_stats.rx_crc_errors = adapter->stats.crcerrs;
	adapter->net_stats.rx_fifo_errors = adapter->stats.mpc;
	adapter->net_stats.rx_missed_errors = adapter->stats.mpc;
	adapter->net_stats.rx_over_errors = adapter->stats.mpc;

	adapter->net_stats.tx_errors = 0;
	adapter->net_stats.rx_frame_errors = 0;
	adapter->net_stats.tx_aborted_errors = 0;
	adapter->net_stats.tx_carrier_errors = 0;
	adapter->net_stats.tx_fifo_errors = 0;
	adapter->net_stats.tx_heartbeat_errors = 0;
	adapter->net_stats.tx_window_errors = 0;
}

#define IXGB_MAX_INTR 10
/**
 * ixgb_intr - Interrupt Handler
 * @irq: interrupt number
 * @data: pointer to a network interface device structure
 **/

static irqreturn_t
ixgb_intr(int irq, void *data)
{
	struct net_device *netdev = data;
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	struct ixgb_hw *hw = &adapter->hw;
	u32 icr = IXGB_READ_REG(hw, ICR);
#ifndef CONFIG_IXGB_NAPI
	unsigned int i;
#endif

	if (unlikely(!icr))
		return IRQ_NONE;  /* Not our interrupt */

	if (unlikely(icr & (IXGB_INT_RXSEQ | IXGB_INT_LSC)))
		if (!test_bit(__IXGB_DOWN, &adapter->flags))
			mod_timer(&adapter->watchdog_timer, jiffies);

#ifdef CONFIG_IXGB_NAPI
	if (netif_rx_schedule_prep(netdev, &adapter->napi)) {

		/* Disable interrupts and register for poll. The flush 
		  of the posted write is intentionally left out.
		*/

		IXGB_WRITE_REG(&adapter->hw, IMC, ~0);
		__netif_rx_schedule(netdev, &adapter->napi);
	}
#else
	/* yes, that is actually a & and it is meant to make sure that
	 * every pass through this for loop checks both receive and
	 * transmit queues for completed descriptors, intended to
	 * avoid starvation issues and assist tx/rx fairness. */
	for(i = 0; i < IXGB_MAX_INTR; i++)
		if (!ixgb_clean_rx_irq(adapter) &
		   !ixgb_clean_tx_irq(adapter))
			break;
#endif 
	return IRQ_HANDLED;
}

#ifdef CONFIG_IXGB_NAPI
/**
 * ixgb_clean - NAPI Rx polling callback
 * @adapter: board private structure
 **/

static int
ixgb_clean(struct napi_struct *napi, int budget)
{
	struct ixgb_adapter *adapter = container_of(napi, struct ixgb_adapter, napi);
	struct net_device *netdev = adapter->netdev;
	int work_done = 0;

	ixgb_clean_tx_irq(adapter);
	ixgb_clean_rx_irq(adapter, &work_done, budget);

	/* If budget not fully consumed, exit the polling mode */
	if (work_done < budget) {
		netif_rx_complete(netdev, napi);
		if (!test_bit(__IXGB_DOWN, &adapter->flags))
			ixgb_irq_enable(adapter);
	}

	return work_done;
}
#endif

/**
 * ixgb_clean_tx_irq - Reclaim resources after transmit completes
 * @adapter: board private structure
 **/

static bool
ixgb_clean_tx_irq(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *tx_ring = &adapter->tx_ring;
	struct net_device *netdev = adapter->netdev;
	struct ixgb_tx_desc *tx_desc, *eop_desc;
	struct ixgb_buffer *buffer_info;
	unsigned int i, eop;
	bool cleaned = false;

	i = tx_ring->next_to_clean;
	eop = tx_ring->buffer_info[i].next_to_watch;
	eop_desc = IXGB_TX_DESC(*tx_ring, eop);

	while (eop_desc->status & IXGB_TX_DESC_STATUS_DD) {

		for (cleaned = false; !cleaned; ) {
			tx_desc = IXGB_TX_DESC(*tx_ring, i);
			buffer_info = &tx_ring->buffer_info[i];

			if (tx_desc->popts
			    & (IXGB_TX_DESC_POPTS_TXSM |
			       IXGB_TX_DESC_POPTS_IXSM))
				adapter->hw_csum_tx_good++;

			ixgb_unmap_and_free_tx_resource(adapter, buffer_info);

			*(u32 *)&(tx_desc->status) = 0;

			cleaned = (i == eop);
			if (++i == tx_ring->count) i = 0;
		}

		eop = tx_ring->buffer_info[i].next_to_watch;
		eop_desc = IXGB_TX_DESC(*tx_ring, eop);
	}

	tx_ring->next_to_clean = i;

	if (unlikely(cleaned && netif_carrier_ok(netdev) &&
		     IXGB_DESC_UNUSED(tx_ring) >= DESC_NEEDED)) {
		/* Make sure that anybody stopping the queue after this
		 * sees the new next_to_clean. */
		smp_mb();

		if (netif_queue_stopped(netdev) &&
		    !(test_bit(__IXGB_DOWN, &adapter->flags))) {
			netif_wake_queue(netdev);
			++adapter->restart_queue;
		}
	}

	if (adapter->detect_tx_hung) {
		/* detect a transmit hang in hardware, this serializes the
		 * check with the clearing of time_stamp and movement of i */
		adapter->detect_tx_hung = false;
		if (tx_ring->buffer_info[eop].dma &&
		   time_after(jiffies, tx_ring->buffer_info[eop].time_stamp + HZ)
		   && !(IXGB_READ_REG(&adapter->hw, STATUS) &
		        IXGB_STATUS_TXOFF)) {
			/* detected Tx unit hang */
			DPRINTK(DRV, ERR, "Detected Tx Unit Hang\n"
					"  TDH                  <%x>\n"
					"  TDT                  <%x>\n"
					"  next_to_use          <%x>\n"
					"  next_to_clean        <%x>\n"
					"buffer_info[next_to_clean]\n"
					"  time_stamp           <%lx>\n"
					"  next_to_watch        <%x>\n"
					"  jiffies              <%lx>\n"
					"  next_to_watch.status <%x>\n",
				IXGB_READ_REG(&adapter->hw, TDH),
				IXGB_READ_REG(&adapter->hw, TDT),
				tx_ring->next_to_use,
				tx_ring->next_to_clean,
				tx_ring->buffer_info[eop].time_stamp,
				eop,
				jiffies,
				eop_desc->status);
			netif_stop_queue(netdev);
		}
	}

	return cleaned;
}

/**
 * ixgb_rx_checksum - Receive Checksum Offload for 82597.
 * @adapter: board private structure
 * @rx_desc: receive descriptor
 * @sk_buff: socket buffer with received data
 **/

static void
ixgb_rx_checksum(struct ixgb_adapter *adapter,
		 struct ixgb_rx_desc *rx_desc,
		 struct sk_buff *skb)
{
	/* Ignore Checksum bit is set OR
	 * TCP Checksum has not been calculated
	 */
	if ((rx_desc->status & IXGB_RX_DESC_STATUS_IXSM) ||
	   (!(rx_desc->status & IXGB_RX_DESC_STATUS_TCPCS))) {
		skb->ip_summed = CHECKSUM_NONE;
		return;
	}

	/* At this point we know the hardware did the TCP checksum */
	/* now look at the TCP checksum error bit */
	if (rx_desc->errors & IXGB_RX_DESC_ERRORS_TCPE) {
		/* let the stack verify checksum errors */
		skb->ip_summed = CHECKSUM_NONE;
		adapter->hw_csum_rx_error++;
	} else {
		/* TCP checksum is good */
		skb->ip_summed = CHECKSUM_UNNECESSARY;
		adapter->hw_csum_rx_good++;
	}
}

/**
 * ixgb_clean_rx_irq - Send received data up the network stack,
 * @adapter: board private structure
 **/

static bool
#ifdef CONFIG_IXGB_NAPI
ixgb_clean_rx_irq(struct ixgb_adapter *adapter, int *work_done, int work_to_do)
#else
ixgb_clean_rx_irq(struct ixgb_adapter *adapter)
#endif
{
	struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
	struct net_device *netdev = adapter->netdev;
	struct pci_dev *pdev = adapter->pdev;
	struct ixgb_rx_desc *rx_desc, *next_rxd;
	struct ixgb_buffer *buffer_info, *next_buffer, *next2_buffer;
	u32 length;
	unsigned int i, j;
	bool cleaned = false;

	i = rx_ring->next_to_clean;
	rx_desc = IXGB_RX_DESC(*rx_ring, i);
	buffer_info = &rx_ring->buffer_info[i];

	while (rx_desc->status & IXGB_RX_DESC_STATUS_DD) {
		struct sk_buff *skb, *next_skb;
		u8 status;

#ifdef CONFIG_IXGB_NAPI
		if (*work_done >= work_to_do)
			break;

		(*work_done)++;
#endif
		status = rx_desc->status;
		skb = buffer_info->skb;
		buffer_info->skb = NULL;

		prefetch(skb->data);

		if (++i == rx_ring->count) i = 0;
		next_rxd = IXGB_RX_DESC(*rx_ring, i);
		prefetch(next_rxd);

		if ((j = i + 1) == rx_ring->count) j = 0;
		next2_buffer = &rx_ring->buffer_info[j];
		prefetch(next2_buffer);

		next_buffer = &rx_ring->buffer_info[i];
		next_skb = next_buffer->skb;
		prefetch(next_skb);

		cleaned = true;

		pci_unmap_single(pdev,
				 buffer_info->dma,
				 buffer_info->length,
				 PCI_DMA_FROMDEVICE);

		length = le16_to_cpu(rx_desc->length);

		if (unlikely(!(status & IXGB_RX_DESC_STATUS_EOP))) {

			/* All receives must fit into a single buffer */

			IXGB_DBG("Receive packet consumed multiple buffers "
					 "length<%x>\n", length);

			dev_kfree_skb_irq(skb);
			goto rxdesc_done;
		}

		if (unlikely(rx_desc->errors
			     & (IXGB_RX_DESC_ERRORS_CE | IXGB_RX_DESC_ERRORS_SE
				| IXGB_RX_DESC_ERRORS_P |
				IXGB_RX_DESC_ERRORS_RXE))) {

			dev_kfree_skb_irq(skb);
			goto rxdesc_done;
		}

		/* code added for copybreak, this should improve
		 * performance for small packets with large amounts
		 * of reassembly being done in the stack */
		if (length < copybreak) {
			struct sk_buff *new_skb =
			    netdev_alloc_skb(netdev, length + NET_IP_ALIGN);
			if (new_skb) {
				skb_reserve(new_skb, NET_IP_ALIGN);
				skb_copy_to_linear_data_offset(new_skb,
							       -NET_IP_ALIGN,
							       (skb->data -
							        NET_IP_ALIGN),
							       (length +
							        NET_IP_ALIGN));
				/* save the skb in buffer_info as good */
				buffer_info->skb = skb;
				skb = new_skb;
			}
		}
		/* end copybreak code */

		/* Good Receive */
		skb_put(skb, length);

		/* Receive Checksum Offload */
		ixgb_rx_checksum(adapter, rx_desc, skb);

		skb->protocol = eth_type_trans(skb, netdev);
#ifdef CONFIG_IXGB_NAPI
		if (adapter->vlgrp && (status & IXGB_RX_DESC_STATUS_VP)) {
			vlan_hwaccel_receive_skb(skb, adapter->vlgrp,
				le16_to_cpu(rx_desc->special));
		} else {
			netif_receive_skb(skb);
		}
#else /* CONFIG_IXGB_NAPI */
		if (adapter->vlgrp && (status & IXGB_RX_DESC_STATUS_VP)) {
			vlan_hwaccel_rx(skb, adapter->vlgrp,
				le16_to_cpu(rx_desc->special));
		} else {
			netif_rx(skb);
		}
#endif /* CONFIG_IXGB_NAPI */
		netdev->last_rx = jiffies;

rxdesc_done:
		/* clean up descriptor, might be written over by hw */
		rx_desc->status = 0;

		/* use prefetched values */
		rx_desc = next_rxd;
		buffer_info = next_buffer;
	}

	rx_ring->next_to_clean = i;

	ixgb_alloc_rx_buffers(adapter);

	return cleaned;
}

/**
 * ixgb_alloc_rx_buffers - Replace used receive buffers
 * @adapter: address of board private structure
 **/

static void
ixgb_alloc_rx_buffers(struct ixgb_adapter *adapter)
{
	struct ixgb_desc_ring *rx_ring = &adapter->rx_ring;
	struct net_device *netdev = adapter->netdev;
	struct pci_dev *pdev = adapter->pdev;
	struct ixgb_rx_desc *rx_desc;
	struct ixgb_buffer *buffer_info;
	struct sk_buff *skb;
	unsigned int i;
	long cleancount;

	i = rx_ring->next_to_use;
	buffer_info = &rx_ring->buffer_info[i];
	cleancount = IXGB_DESC_UNUSED(rx_ring);


	/* leave three descriptors unused */
	while (--cleancount > 2) {
		/* recycle! its good for you */
		skb = buffer_info->skb;
		if (skb) {
			skb_trim(skb, 0);
			goto map_skb;
		}

		skb = netdev_alloc_skb(netdev, adapter->rx_buffer_len
			               + NET_IP_ALIGN);
		if (unlikely(!skb)) {
			/* Better luck next round */
			adapter->alloc_rx_buff_failed++;
			break;
		}

		/* Make buffer alignment 2 beyond a 16 byte boundary
		 * this will result in a 16 byte aligned IP header after
		 * the 14 byte MAC header is removed
		 */
		skb_reserve(skb, NET_IP_ALIGN);

		buffer_info->skb = skb;
		buffer_info->length = adapter->rx_buffer_len;
map_skb:
		buffer_info->dma = pci_map_single(pdev,
		                                  skb->data,
		                                  adapter->rx_buffer_len,
		                                  PCI_DMA_FROMDEVICE);

		rx_desc = IXGB_RX_DESC(*rx_ring, i);
		rx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
		/* guarantee DD bit not set now before h/w gets descriptor
		 * this is the rest of the workaround for h/w double 
		 * writeback. */
		rx_desc->status = 0;


		if (++i == rx_ring->count) i = 0;
		buffer_info = &rx_ring->buffer_info[i];
	}

	if (likely(rx_ring->next_to_use != i)) {
		rx_ring->next_to_use = i;
		if (unlikely(i-- == 0))
			i = (rx_ring->count - 1);

		/* Force memory writes to complete before letting h/w
		 * know there are new descriptors to fetch.  (Only
		 * applicable for weak-ordered memory model archs, such
		 * as IA-64). */
		wmb();
		IXGB_WRITE_REG(&adapter->hw, RDT, i);
	}
}

/**
 * ixgb_vlan_rx_register - enables or disables vlan tagging/stripping.
 * 
 * @param netdev network interface device structure
 * @param grp indicates to enable or disable tagging/stripping
 **/
static void
ixgb_vlan_rx_register(struct net_device *netdev, struct vlan_group *grp)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	u32 ctrl, rctl;

	ixgb_irq_disable(adapter);
	adapter->vlgrp = grp;

	if (grp) {
		/* enable VLAN tag insert/strip */
		ctrl = IXGB_READ_REG(&adapter->hw, CTRL0);
		ctrl |= IXGB_CTRL0_VME;
		IXGB_WRITE_REG(&adapter->hw, CTRL0, ctrl);

		/* enable VLAN receive filtering */

		rctl = IXGB_READ_REG(&adapter->hw, RCTL);
		rctl |= IXGB_RCTL_VFE;
		rctl &= ~IXGB_RCTL_CFIEN;
		IXGB_WRITE_REG(&adapter->hw, RCTL, rctl);
	} else {
		/* disable VLAN tag insert/strip */

		ctrl = IXGB_READ_REG(&adapter->hw, CTRL0);
		ctrl &= ~IXGB_CTRL0_VME;
		IXGB_WRITE_REG(&adapter->hw, CTRL0, ctrl);

		/* disable VLAN filtering */

		rctl = IXGB_READ_REG(&adapter->hw, RCTL);
		rctl &= ~IXGB_RCTL_VFE;
		IXGB_WRITE_REG(&adapter->hw, RCTL, rctl);
	}

	/* don't enable interrupts unless we are UP */
	if (adapter->netdev->flags & IFF_UP)
		ixgb_irq_enable(adapter);
}

static void
ixgb_vlan_rx_add_vid(struct net_device *netdev, u16 vid)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	u32 vfta, index;

	/* add VID to filter table */

	index = (vid >> 5) & 0x7F;
	vfta = IXGB_READ_REG_ARRAY(&adapter->hw, VFTA, index);
	vfta |= (1 << (vid & 0x1F));
	ixgb_write_vfta(&adapter->hw, index, vfta);
}

static void
ixgb_vlan_rx_kill_vid(struct net_device *netdev, u16 vid)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	u32 vfta, index;

	ixgb_irq_disable(adapter);

	vlan_group_set_device(adapter->vlgrp, vid, NULL);

	/* don't enable interrupts unless we are UP */
	if (adapter->netdev->flags & IFF_UP)
		ixgb_irq_enable(adapter);

	/* remove VID from filter table */

	index = (vid >> 5) & 0x7F;
	vfta = IXGB_READ_REG_ARRAY(&adapter->hw, VFTA, index);
	vfta &= ~(1 << (vid & 0x1F));
	ixgb_write_vfta(&adapter->hw, index, vfta);
}

static void
ixgb_restore_vlan(struct ixgb_adapter *adapter)
{
	ixgb_vlan_rx_register(adapter->netdev, adapter->vlgrp);

	if (adapter->vlgrp) {
		u16 vid;
		for(vid = 0; vid < VLAN_GROUP_ARRAY_LEN; vid++) {
			if (!vlan_group_get_device(adapter->vlgrp, vid))
				continue;
			ixgb_vlan_rx_add_vid(adapter->netdev, vid);
		}
	}
}

#ifdef CONFIG_NET_POLL_CONTROLLER
/*
 * Polling 'interrupt' - used by things like netconsole to send skbs
 * without having to re-enable interrupts. It's not called while
 * the interrupt routine is executing.
 */

static void ixgb_netpoll(struct net_device *dev)
{
	struct ixgb_adapter *adapter = netdev_priv(dev);

	disable_irq(adapter->pdev->irq);
	ixgb_intr(adapter->pdev->irq, dev);
	enable_irq(adapter->pdev->irq);
}
#endif

/**
 * ixgb_io_error_detected() - called when PCI error is detected
 * @pdev    pointer to pci device with error
 * @state   pci channel state after error
 *
 * This callback is called by the PCI subsystem whenever
 * a PCI bus error is detected.
 */
static pci_ers_result_t ixgb_io_error_detected (struct pci_dev *pdev,
			             enum pci_channel_state state)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	if (netif_running(netdev))
		ixgb_down(adapter, true);

	pci_disable_device(pdev);

	/* Request a slot reset. */
	return PCI_ERS_RESULT_NEED_RESET;
}

/**
 * ixgb_io_slot_reset - called after the pci bus has been reset.
 * @pdev    pointer to pci device with error
 *
 * This callback is called after the PCI buss has been reset.
 * Basically, this tries to restart the card from scratch.
 * This is a shortened version of the device probe/discovery code,
 * it resembles the first-half of the ixgb_probe() routine.
 */
static pci_ers_result_t ixgb_io_slot_reset (struct pci_dev *pdev)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	if (pci_enable_device(pdev)) {
		DPRINTK(PROBE, ERR, "Cannot re-enable PCI device after reset.\n");
		return PCI_ERS_RESULT_DISCONNECT;
	}

	/* Perform card reset only on one instance of the card */
	if (0 != PCI_FUNC (pdev->devfn))
		return PCI_ERS_RESULT_RECOVERED;

	pci_set_master(pdev);

	netif_carrier_off(netdev);
	netif_stop_queue(netdev);
	ixgb_reset(adapter);

	/* Make sure the EEPROM is good */
	if (!ixgb_validate_eeprom_checksum(&adapter->hw)) {
		DPRINTK(PROBE, ERR, "After reset, the EEPROM checksum is not valid.\n");
		return PCI_ERS_RESULT_DISCONNECT;
	}
	ixgb_get_ee_mac_addr(&adapter->hw, netdev->dev_addr);
	memcpy(netdev->perm_addr, netdev->dev_addr, netdev->addr_len);

	if (!is_valid_ether_addr(netdev->perm_addr)) {
		DPRINTK(PROBE, ERR, "After reset, invalid MAC address.\n");
		return PCI_ERS_RESULT_DISCONNECT;
	}

	return PCI_ERS_RESULT_RECOVERED;
}

/**
 * ixgb_io_resume - called when its OK to resume normal operations
 * @pdev    pointer to pci device with error
 *
 * The error recovery driver tells us that its OK to resume
 * normal operation. Implementation resembles the second-half
 * of the ixgb_probe() routine.
 */
static void ixgb_io_resume (struct pci_dev *pdev)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	pci_set_master(pdev);

	if (netif_running(netdev)) {
		if (ixgb_up(adapter)) {
			printk ("ixgb: can't bring device back up after reset\n");
			return;
		}
	}

	netif_device_attach(netdev);
	mod_timer(&adapter->watchdog_timer, jiffies);
}

/* ixgb_main.c */