xref: /OK3568_Linux_fs/kernel/drivers/net/ethernet/intel/ixgb/ixgb_main.c (revision 4882a59341e53eb6f0b4789bf948001014eff981)

// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 1999 - 2008 Intel Corporation. */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/prefetch.h>
#include "ixgb.h"

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

static const char ixgb_copyright[] = "Copyright (c) 1999-2008 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 const struct pci_device_id ixgb_pci_tbl[] = {
	{PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX_CX4,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{PCI_VENDOR_ID_INTEL, IXGB_DEVICE_ID_82597EX_SR,
	 PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
	{PCI_VENDOR_ID_INTEL, 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 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(struct timer_list *t);
static netdev_tx_t ixgb_xmit_frame(struct sk_buff *skb,
				   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);

static int ixgb_clean(struct napi_struct *, int);
static bool ixgb_clean_rx_irq(struct ixgb_adapter *, int *, int);
static void ixgb_alloc_rx_buffers(struct ixgb_adapter *, int);

static void ixgb_tx_timeout(struct net_device *dev, unsigned int txqueue);
static void ixgb_tx_timeout_task(struct work_struct *work);

static void ixgb_vlan_strip_enable(struct ixgb_adapter *adapter);
static void ixgb_vlan_strip_disable(struct ixgb_adapter *adapter);
static int ixgb_vlan_rx_add_vid(struct net_device *netdev,
				__be16 proto, u16 vid);
static int ixgb_vlan_rx_kill_vid(struct net_device *netdev,
				 __be16 proto, u16 vid);
static void ixgb_restore_vlan(struct ixgb_adapter *adapter);

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

static const 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   = 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 v2");

#define DEFAULT_MSG_ENABLE (NETIF_MSG_DRV|NETIF_MSG_PROBE|NETIF_MSG_LINK)
static int debug = -1;
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)
{
	pr_info("%s\n", ixgb_driver_string);
	pr_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 == PCI_VENDOR_ID_SUN)
		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, IXGB_DESC_UNUSED(&adapter->rx_ring));

	/* 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 = true;
			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);
		netif_err(adapter, probe, adapter->netdev,
			  "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);

	napi_enable(&adapter->napi);
	ixgb_irq_enable(adapter);

	netif_wake_queue(netdev);

	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);

	netif_carrier_off(netdev);

	napi_disable(&adapter->napi);
	/* 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_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))
		netif_err(adapter, probe, adapter->netdev, "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);
		}
	}
}

static netdev_features_t
ixgb_fix_features(struct net_device *netdev, netdev_features_t features)
{
	/*
	 * Tx VLAN insertion does not work per HW design when Rx stripping is
	 * disabled.
	 */
	if (!(features & NETIF_F_HW_VLAN_CTAG_RX))
		features &= ~NETIF_F_HW_VLAN_CTAG_TX;

	return features;
}

static int
ixgb_set_features(struct net_device *netdev, netdev_features_t features)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	netdev_features_t changed = features ^ netdev->features;

	if (!(changed & (NETIF_F_RXCSUM|NETIF_F_HW_VLAN_CTAG_RX)))
		return 0;

	adapter->rx_csum = !!(features & NETIF_F_RXCSUM);

	if (netif_running(netdev)) {
		ixgb_down(adapter, true);
		ixgb_up(adapter);
		ixgb_set_speed_duplex(netdev);
	} else
		ixgb_reset(adapter);

	return 0;
}


static const struct net_device_ops ixgb_netdev_ops = {
	.ndo_open 		= ixgb_open,
	.ndo_stop		= ixgb_close,
	.ndo_start_xmit		= ixgb_xmit_frame,
	.ndo_set_rx_mode	= ixgb_set_multi,
	.ndo_validate_addr	= eth_validate_addr,
	.ndo_set_mac_address	= ixgb_set_mac,
	.ndo_change_mtu		= ixgb_change_mtu,
	.ndo_tx_timeout		= ixgb_tx_timeout,
	.ndo_vlan_rx_add_vid	= ixgb_vlan_rx_add_vid,
	.ndo_vlan_rx_kill_vid	= ixgb_vlan_rx_kill_vid,
	.ndo_fix_features       = ixgb_fix_features,
	.ndo_set_features       = ixgb_set_features,
};

/**
 * 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
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;

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

	pci_using_dac = 0;
	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
	if (!err) {
		pci_using_dac = 1;
	} else {
		err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
		if (err) {
			pr_err("No usable DMA configuration, aborting\n");
			goto err_dma_mask;
		}
	}

	err = pci_request_regions(pdev, ixgb_driver_name);
	if (err)
		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_MSG_ENABLE);

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

	for (i = BAR_1; i < PCI_STD_NUM_BARS; 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->netdev_ops = &ixgb_netdev_ops;
	ixgb_set_ethtool_ops(netdev);
	netdev->watchdog_timeo = 5 * HZ;
	netif_napi_add(netdev, &adapter->napi, ixgb_clean, 64);

	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 */

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

	netdev->hw_features = NETIF_F_SG |
			   NETIF_F_TSO |
			   NETIF_F_HW_CSUM |
			   NETIF_F_HW_VLAN_CTAG_TX |
			   NETIF_F_HW_VLAN_CTAG_RX;
	netdev->features = netdev->hw_features |
			   NETIF_F_HW_VLAN_CTAG_FILTER;
	netdev->hw_features |= NETIF_F_RXCSUM;

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

	/* MTU range: 68 - 16114 */
	netdev->min_mtu = ETH_MIN_MTU;
	netdev->max_mtu = IXGB_MAX_JUMBO_FRAME_SIZE - ETH_HLEN;

	/* make sure the EEPROM is good */

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

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

	if (!is_valid_ether_addr(netdev->dev_addr)) {
		netif_err(adapter, probe, adapter->netdev, "Invalid MAC Address\n");
		err = -EIO;
		goto err_eeprom;
	}

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

	timer_setup(&adapter->watchdog_timer, ixgb_watchdog, 0);

	INIT_WORK(&adapter->tx_timeout_task, ixgb_tx_timeout_task);

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

	/* carrier off reporting is important to ethtool even BEFORE open */
	netif_carrier_off(netdev);

	netif_info(adapter, probe, adapter->netdev,
		   "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
ixgb_remove(struct pci_dev *pdev)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	cancel_work_sync(&adapter->tx_timeout_task);

	unregister_netdev(netdev);

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

	free_netdev(netdev);
	pci_disable_device(pdev);
}

/**
 * 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
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 */
		netif_err(adapter, probe, adapter->netdev, "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 */
	err = ixgb_setup_tx_resources(adapter);
	if (err)
		goto err_setup_tx;

	netif_carrier_off(netdev);

	/* allocate receive descriptors */

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

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

	netif_start_queue(netdev);

	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 = vzalloc(size);
	if (!txdr->buffer_info)
		return -ENOMEM;

	/* round up to nearest 4K */

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

	txdr->desc = dma_alloc_coherent(&pdev->dev, txdr->size, &txdr->dma,
					GFP_KERNEL);
	if (!txdr->desc) {
		vfree(txdr->buffer_info);
		return -ENOMEM;
	}

	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 = vzalloc(size);
	if (!rxdr->buffer_info)
		return -ENOMEM;

	/* Round up to nearest 4K */

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

	rxdr->desc = dma_alloc_coherent(&pdev->dev, rxdr->size, &rxdr->dma,
					GFP_KERNEL);

	if (!rxdr->desc) {
		vfree(rxdr->buffer_info);
		return -ENOMEM;
	}

	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;

	dma_free_coherent(&pdev->dev, 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)
{
	if (buffer_info->dma) {
		if (buffer_info->mapped_as_page)
			dma_unmap_page(&adapter->pdev->dev, buffer_info->dma,
				       buffer_info->length, DMA_TO_DEVICE);
		else
			dma_unmap_single(&adapter->pdev->dev, buffer_info->dma,
					 buffer_info->length, DMA_TO_DEVICE);
		buffer_info->dma = 0;
	}

	if (buffer_info->skb) {
		dev_kfree_skb_any(buffer_info->skb);
		buffer_info->skb = NULL;
	}
	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;

	dma_free_coherent(&pdev->dev, 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->dma) {
			dma_unmap_single(&pdev->dev,
					 buffer_info->dma,
					 buffer_info->length,
					 DMA_FROM_DEVICE);
			buffer_info->dma = 0;
			buffer_info->length = 0;
		}

		if (buffer_info->skb) {
			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 netdev_hw_addr *ha;
	u32 rctl;

	/* 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);
		/* disable VLAN filtering */
		rctl &= ~IXGB_RCTL_CFIEN;
		rctl &= ~IXGB_RCTL_VFE;
	} else {
		if (netdev->flags & IFF_ALLMULTI) {
			rctl |= IXGB_RCTL_MPE;
			rctl &= ~IXGB_RCTL_UPE;
		} else {
			rctl &= ~(IXGB_RCTL_UPE | IXGB_RCTL_MPE);
		}
		/* enable VLAN filtering */
		rctl |= IXGB_RCTL_VFE;
		rctl &= ~IXGB_RCTL_CFIEN;
	}

	if (netdev_mc_count(netdev) > IXGB_MAX_NUM_MULTICAST_ADDRESSES) {
		rctl |= IXGB_RCTL_MPE;
		IXGB_WRITE_REG(hw, RCTL, rctl);
	} else {
		u8 *mta = kmalloc_array(ETH_ALEN,
				        IXGB_MAX_NUM_MULTICAST_ADDRESSES,
				        GFP_ATOMIC);
		u8 *addr;
		if (!mta)
			goto alloc_failed;

		IXGB_WRITE_REG(hw, RCTL, rctl);

		addr = mta;
		netdev_for_each_mc_addr(ha, netdev) {
			memcpy(addr, ha->addr, ETH_ALEN);
			addr += ETH_ALEN;
		}

		ixgb_mc_addr_list_update(hw, mta, netdev_mc_count(netdev), 0);
		kfree(mta);
	}

alloc_failed:
	if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX)
		ixgb_vlan_strip_enable(adapter);
	else
		ixgb_vlan_strip_disable(adapter);

}

/**
 * ixgb_watchdog - Timer Call-back
 * @t: pointer to timer_list containing our private info pointer
 **/

static void
ixgb_watchdog(struct timer_list *t)
{
	struct ixgb_adapter *adapter = from_timer(adapter, t, watchdog_timer);
	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)) {
			netdev_info(netdev,
				    "NIC Link is Up 10 Gbps Full Duplex, Flow Control: %s\n",
				    (adapter->hw.fc.type == ixgb_fc_full) ?
				    "RX/TX" :
				    (adapter->hw.fc.type == ixgb_fc_rx_pause) ?
				     "RX" :
				    (adapter->hw.fc.type == ixgb_fc_tx_pause) ?
				    "TX" : "None");
			adapter->link_speed = 10000;
			adapter->link_duplex = FULL_DUPLEX;
			netif_carrier_on(netdev);
		}
	} else {
		if (netif_carrier_ok(netdev)) {
			adapter->link_speed = 0;
			adapter->link_duplex = 0;
			netdev_info(netdev, "NIC Link is Down\n");
			netif_carrier_off(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);
			/* return immediately since reset is imminent */
			return;
		}
	}

	/* 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;

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

		err = skb_cow_head(skb, 0);
		if (err < 0)
			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_checksum_start_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 pci_dev *pdev = adapter->pdev;
	struct ixgb_buffer *buffer_info;
	int len = skb_headlen(skb);
	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;

	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->mapped_as_page = false;
		buffer_info->dma = dma_map_single(&pdev->dev,
						  skb->data + offset,
						  size, DMA_TO_DEVICE);
		if (dma_mapping_error(&pdev->dev, buffer_info->dma))
			goto dma_error;
		buffer_info->next_to_watch = 0;

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

	for (f = 0; f < nr_frags; f++) {
		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
		len = skb_frag_size(frag);
		offset = 0;

		while (len) {
			i++;
			if (i == tx_ring->count)
				i = 0;

			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->mapped_as_page = true;
			buffer_info->dma =
				skb_frag_dma_map(&pdev->dev, frag, offset, size,
						 DMA_TO_DEVICE);
			if (dma_mapping_error(&pdev->dev, buffer_info->dma))
				goto dma_error;
			buffer_info->next_to_watch = 0;

			len -= size;
			offset += size;
			count++;
		}
	}
	tx_ring->buffer_info[i].skb = skb;
	tx_ring->buffer_info[first].next_to_watch = i;

	return count;

dma_error:
	dev_err(&pdev->dev, "TX DMA map failed\n");
	buffer_info->dma = 0;
	if (count)
		count--;

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

	return 0;
}

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 netdev_tx_t
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 count = 0;
	int tso;

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

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

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

	if (skb_vlan_tag_present(skb)) {
		tx_flags |= IXGB_TX_FLAGS_VLAN;
		vlan_id = skb_vlan_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;

	count = ixgb_tx_map(adapter, skb, first);

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

	} else {
		dev_kfree_skb_any(skb);
		adapter->tx_ring.buffer_info[first].time_stamp = 0;
		adapter->tx_ring.next_to_use = first;
	}

	return NETDEV_TX_OK;
}

/**
 * ixgb_tx_timeout - Respond to a Tx Hang
 * @netdev: network interface device structure
 * @txqueue: queue hanging (unused)
 **/

static void
ixgb_tx_timeout(struct net_device *netdev, unsigned int __always_unused txqueue)
{
	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_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;

	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(netdev) > 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 */

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

	/* ignore RLEC as it reports errors for padded (<64bytes) frames
	 * with a length in the type/len field */
	netdev->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
	 * netdev->stats.rx_length_errors = adapter->stats.rlec;
	 */

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

	netdev->stats.tx_errors = 0;
	netdev->stats.rx_frame_errors = 0;
	netdev->stats.tx_aborted_errors = 0;
	netdev->stats.tx_carrier_errors = 0;
	netdev->stats.tx_fifo_errors = 0;
	netdev->stats.tx_heartbeat_errors = 0;
	netdev->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);

	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);

	if (napi_schedule_prep(&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);
		__napi_schedule(&adapter->napi);
	}
	return IRQ_HANDLED;
}

/**
 * ixgb_clean - NAPI Rx polling callback
 * @napi: napi struct pointer
 * @budget: max number of receives to clean
 **/

static int
ixgb_clean(struct napi_struct *napi, int budget)
{
	struct ixgb_adapter *adapter = container_of(napi, struct ixgb_adapter, napi);
	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) {
		napi_complete_done(napi, work_done);
		if (!test_bit(__IXGB_DOWN, &adapter->flags))
			ixgb_irq_enable(adapter);
	}

	return work_done;
}

/**
 * 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) {

		rmb(); /* read buffer_info after eop_desc */
		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].time_stamp &&
		   time_after(jiffies, tx_ring->buffer_info[eop].time_stamp + HZ)
		   && !(IXGB_READ_REG(&adapter->hw, STATUS) &
		        IXGB_STATUS_TXOFF)) {
			/* detected Tx unit hang */
			netif_err(adapter, drv, adapter->netdev,
				  "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
 * @skb: 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_checksum_none_assert(skb);
		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_checksum_none_assert(skb);
		adapter->hw_csum_rx_error++;
	} else {
		/* TCP checksum is good */
		skb->ip_summed = CHECKSUM_UNNECESSARY;
		adapter->hw_csum_rx_good++;
	}
}

/*
 * this should improve performance for small packets with large amounts
 * of reassembly being done in the stack
 */
static void ixgb_check_copybreak(struct napi_struct *napi,
				 struct ixgb_buffer *buffer_info,
				 u32 length, struct sk_buff **skb)
{
	struct sk_buff *new_skb;

	if (length > copybreak)
		return;

	new_skb = napi_alloc_skb(napi, length);
	if (!new_skb)
		return;

	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;
}

/**
 * ixgb_clean_rx_irq - Send received data up the network stack,
 * @adapter: board private structure
 * @work_done: output pointer to amount of packets cleaned
 * @work_to_do: how much work we can complete
 **/

static bool
ixgb_clean_rx_irq(struct ixgb_adapter *adapter, int *work_done, int work_to_do)
{
	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;
	int cleaned_count = 0;
	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;
		u8 status;

		if (*work_done >= work_to_do)
			break;

		(*work_done)++;
		rmb();	/* read descriptor and rx_buffer_info after status DD */
		status = rx_desc->status;
		skb = buffer_info->skb;
		buffer_info->skb = NULL;

		prefetch(skb->data - NET_IP_ALIGN);

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

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

		next_buffer = &rx_ring->buffer_info[i];

		cleaned = true;
		cleaned_count++;

		dma_unmap_single(&pdev->dev,
				 buffer_info->dma,
				 buffer_info->length,
				 DMA_FROM_DEVICE);
		buffer_info->dma = 0;

		length = le16_to_cpu(rx_desc->length);
		rx_desc->length = 0;

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

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

			pr_debug("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;
		}

		ixgb_check_copybreak(&adapter->napi, buffer_info, length, &skb);

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

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

		skb->protocol = eth_type_trans(skb, netdev);
		if (status & IXGB_RX_DESC_STATUS_VP)
			__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
				       le16_to_cpu(rx_desc->special));

		netif_receive_skb(skb);

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

		/* return some buffers to hardware, one at a time is too slow */
		if (unlikely(cleaned_count >= IXGB_RX_BUFFER_WRITE)) {
			ixgb_alloc_rx_buffers(adapter, cleaned_count);
			cleaned_count = 0;
		}

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

	rx_ring->next_to_clean = i;

	cleaned_count = IXGB_DESC_UNUSED(rx_ring);
	if (cleaned_count)
		ixgb_alloc_rx_buffers(adapter, cleaned_count);

	return cleaned;
}

/**
 * ixgb_alloc_rx_buffers - Replace used receive buffers
 * @adapter: address of board private structure
 * @cleaned_count: how many buffers to allocate
 **/

static void
ixgb_alloc_rx_buffers(struct ixgb_adapter *adapter, int cleaned_count)
{
	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 && cleaned_count--) {
		/* recycle! its good for you */
		skb = buffer_info->skb;
		if (skb) {
			skb_trim(skb, 0);
			goto map_skb;
		}

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

		buffer_info->skb = skb;
		buffer_info->length = adapter->rx_buffer_len;
map_skb:
		buffer_info->dma = dma_map_single(&pdev->dev,
		                                  skb->data,
		                                  adapter->rx_buffer_len,
						  DMA_FROM_DEVICE);
		if (dma_mapping_error(&pdev->dev, buffer_info->dma)) {
			adapter->alloc_rx_buff_failed++;
			break;
		}

		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);
	}
}

static void
ixgb_vlan_strip_enable(struct ixgb_adapter *adapter)
{
	u32 ctrl;

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

static void
ixgb_vlan_strip_disable(struct ixgb_adapter *adapter)
{
	u32 ctrl;

	/* disable VLAN tag insert/strip */
	ctrl = IXGB_READ_REG(&adapter->hw, CTRL0);
	ctrl &= ~IXGB_CTRL0_VME;
	IXGB_WRITE_REG(&adapter->hw, CTRL0, ctrl);
}

static int
ixgb_vlan_rx_add_vid(struct net_device *netdev, __be16 proto, 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);
	set_bit(vid, adapter->active_vlans);

	return 0;
}

static int
ixgb_vlan_rx_kill_vid(struct net_device *netdev, __be16 proto, u16 vid)
{
	struct ixgb_adapter *adapter = netdev_priv(netdev);
	u32 vfta, index;

	/* 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);
	clear_bit(vid, adapter->active_vlans);

	return 0;
}

static void
ixgb_restore_vlan(struct ixgb_adapter *adapter)
{
	u16 vid;

	for_each_set_bit(vid, adapter->active_vlans, VLAN_N_VID)
		ixgb_vlan_rx_add_vid(adapter->netdev, htons(ETH_P_8021Q), vid);
}

/**
 * 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,
                                               pci_channel_state_t state)
{
	struct net_device *netdev = pci_get_drvdata(pdev);
	struct ixgb_adapter *adapter = netdev_priv(netdev);

	netif_device_detach(netdev);

	if (state == pci_channel_io_perm_failure)
		return PCI_ERS_RESULT_DISCONNECT;

	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 bus 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)) {
		netif_err(adapter, probe, adapter->netdev,
			  "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)) {
		netif_err(adapter, probe, adapter->netdev,
			  "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)) {
		netif_err(adapter, probe, adapter->netdev,
			  "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)) {
			pr_err("can't bring device back up after reset\n");
			return;
		}
	}

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

/* ixgb_main.c */