igc: Add interrupt support

This patch set adds interrupt support for the igc interfaces.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igc/igc.h

@@ -28,6 +28,17 @@
 extern char igc_driver_name[];
 extern char igc_driver_version[];
 
+/* Interrupt defines */
+#define IGC_START_ITR			648 /* ~6000 ints/sec */
+#define IGC_FLAG_HAS_MSI		BIT(0)
+#define IGC_FLAG_QUEUE_PAIRS		BIT(4)
+#define IGC_FLAG_HAS_MSIX		BIT(13)
+
+#define IGC_START_ITR			648 /* ~6000 ints/sec */
+#define IGC_4K_ITR			980
+#define IGC_20K_ITR			196
+#define IGC_70K_ITR			56
+
 /* Transmit and receive queues */
 #define IGC_MAX_RX_QUEUES		4
 #define IGC_MAX_TX_QUEUES		4
@@ -42,10 +53,96 @@ enum igc_state_t {
 	__IGC_PTP_TX_IN_PROGRESS,
 };
 
+struct igc_tx_queue_stats {
+	u64 packets;
+	u64 bytes;
+	u64 restart_queue;
+};
+
+struct igc_rx_queue_stats {
+	u64 packets;
+	u64 bytes;
+	u64 drops;
+	u64 csum_err;
+	u64 alloc_failed;
+};
+
+struct igc_rx_packet_stats {
+	u64 ipv4_packets;      /* IPv4 headers processed */
+	u64 ipv4e_packets;     /* IPv4E headers with extensions processed */
+	u64 ipv6_packets;      /* IPv6 headers processed */
+	u64 ipv6e_packets;     /* IPv6E headers with extensions processed */
+	u64 tcp_packets;       /* TCP headers processed */
+	u64 udp_packets;       /* UDP headers processed */
+	u64 sctp_packets;      /* SCTP headers processed */
+	u64 nfs_packets;       /* NFS headers processe */
+	u64 other_packets;
+};
+
+struct igc_ring_container {
+	struct igc_ring *ring;          /* pointer to linked list of rings */
+	unsigned int total_bytes;       /* total bytes processed this int */
+	unsigned int total_packets;     /* total packets processed this int */
+	u16 work_limit;                 /* total work allowed per interrupt */
+	u8 count;                       /* total number of rings in vector */
+	u8 itr;                         /* current ITR setting for ring */
+};
+
+struct igc_ring {
+	struct igc_q_vector *q_vector;  /* backlink to q_vector */
+	struct net_device *netdev;      /* back pointer to net_device */
+	struct device *dev;             /* device for dma mapping */
+	union {                         /* array of buffer info structs */
+		struct igc_tx_buffer *tx_buffer_info;
+		struct igc_rx_buffer *rx_buffer_info;
+	};
+	void *desc;                     /* descriptor ring memory */
+	unsigned long flags;            /* ring specific flags */
+	void __iomem *tail;             /* pointer to ring tail register */
+	dma_addr_t dma;                 /* phys address of the ring */
+	unsigned int size;              /* length of desc. ring in bytes */
+
+	u16 count;                      /* number of desc. in the ring */
+	u8 queue_index;                 /* logical index of the ring*/
+	u8 reg_idx;                     /* physical index of the ring */
+
+	/* everything past this point are written often */
+	u16 next_to_clean;
+	u16 next_to_use;
+	u16 next_to_alloc;
+
+	union {
+		/* TX */
+		struct {
+			struct igc_tx_queue_stats tx_stats;
+		};
+		/* RX */
+		struct {
+			struct igc_rx_queue_stats rx_stats;
+			struct igc_rx_packet_stats pkt_stats;
+			struct sk_buff *skb;
+		};
+	};
+} ____cacheline_internodealigned_in_smp;
+
 struct igc_q_vector {
 	struct igc_adapter *adapter;    /* backlink */
+	void __iomem *itr_register;
+	u32 eims_value;                 /* EIMS mask value */
+
+	u16 itr_val;
+	u8 set_itr;
+
+	struct igc_ring_container rx, tx;
 
 	struct napi_struct napi;
+
+	struct rcu_head rcu;    /* to avoid race with update stats on free */
+	char name[IFNAMSIZ + 9];
+	struct net_device poll_dev;
+
+	/* for dynamic allocation of rings associated with this q_vector */
+	struct igc_ring ring[0] ____cacheline_internodealigned_in_smp;
 };
 
 struct igc_mac_addr {
@@ -65,13 +162,35 @@ struct igc_adapter {
 	unsigned long state;
 	unsigned int flags;
 	unsigned int num_q_vectors;
+
+	struct msix_entry *msix_entries;
+
+	/* TX */
+	u16 tx_work_limit;
+	int num_tx_queues;
+	struct igc_ring *tx_ring[IGC_MAX_TX_QUEUES];
+
+	/* RX */
+	int num_rx_queues;
+	struct igc_ring *rx_ring[IGC_MAX_RX_QUEUES];
+
+	struct timer_list watchdog_timer;
+	struct timer_list dma_err_timer;
+	struct timer_list phy_info_timer;
+
 	u16 link_speed;
 	u16 link_duplex;
 
 	u8 port_num;
 
 	u8 __iomem *io_addr;
+	/* Interrupt Throttle Rate */
+	u32 rx_itr_setting;
+	u32 tx_itr_setting;
+
+	struct work_struct reset_task;
 	struct work_struct watchdog_task;
+	struct work_struct dma_err_task;
 
 	int msg_enable;
 	u32 max_frame_size;
@@ -81,8 +200,16 @@ struct igc_adapter {
 
 	/* structs defined in igc_hw.h */
 	struct igc_hw hw;
+	struct igc_hw_stats stats;
 
 	struct igc_q_vector *q_vector[MAX_Q_VECTORS];
+	u32 eims_enable_mask;
+	u32 eims_other;
+
+	u16 tx_ring_count;
+	u16 rx_ring_count;
+
+	u32 rss_queues;
 
 	struct igc_mac_addr *mac_table;
 };

drivers/net/ethernet/intel/igc/igc_defines.h

@@ -42,4 +42,44 @@
 #define IGC_STATUS_SPEED_100	0x00000040      /* Speed 100Mb/s */
 #define IGC_STATUS_SPEED_1000	0x00000080      /* Speed 1000Mb/s */
 
+/* Interrupt Cause Read */
+#define IGC_ICR_TXDW		BIT(0)	/* Transmit desc written back */
+#define IGC_ICR_TXQE		BIT(1)	/* Transmit Queue empty */
+#define IGC_ICR_LSC		BIT(2)	/* Link Status Change */
+#define IGC_ICR_RXSEQ		BIT(3)	/* Rx sequence error */
+#define IGC_ICR_RXDMT0		BIT(4)	/* Rx desc min. threshold (0) */
+#define IGC_ICR_RXO		BIT(6)	/* Rx overrun */
+#define IGC_ICR_RXT0		BIT(7)	/* Rx timer intr (ring 0) */
+#define IGC_ICR_DRSTA		BIT(30)	/* Device Reset Asserted */
+#define IGC_ICS_RXT0		IGC_ICR_RXT0 /* Rx timer intr */
+
+#define IMS_ENABLE_MASK ( \
+	IGC_IMS_RXT0   |    \
+	IGC_IMS_TXDW   |    \
+	IGC_IMS_RXDMT0 |    \
+	IGC_IMS_RXSEQ  |    \
+	IGC_IMS_LSC)
+
+/* Interrupt Mask Set */
+#define IGC_IMS_TXDW		IGC_ICR_TXDW	/* Tx desc written back */
+#define IGC_IMS_RXSEQ		IGC_ICR_RXSEQ	/* Rx sequence error */
+#define IGC_IMS_LSC		IGC_ICR_LSC	/* Link Status Change */
+#define IGC_IMS_DOUTSYNC	IGC_ICR_DOUTSYNC /* NIC DMA out of sync */
+#define IGC_IMS_DRSTA		IGC_ICR_DRSTA	/* Device Reset Asserted */
+#define IGC_IMS_RXT0		IGC_ICR_RXT0	/* Rx timer intr */
+#define IGC_IMS_RXDMT0		IGC_ICR_RXDMT0	/* Rx desc min. threshold */
+
+#define IGC_QVECTOR_MASK	0x7FFC		/* Q-vector mask */
+#define IGC_ITR_VAL_MASK	0x04		/* ITR value mask */
+
+#define IGC_ICR_DOUTSYNC	0x10000000 /* NIC DMA out of sync */
+#define IGC_EITR_CNT_IGNR	0x80000000 /* Don't reset counters on write */
+#define IGC_IVAR_VALID		0x80
+#define IGC_GPIE_NSICR		0x00000001
+#define IGC_GPIE_MSIX_MODE	0x00000010
+#define IGC_GPIE_EIAME		0x40000000
+#define IGC_GPIE_PBA		0x80000000
+
+#define IGC_N0_QUEUE -1
+
 #endif /* _IGC_DEFINES_H_ */

drivers/net/ethernet/intel/igc/igc_hw.h

@@ -85,6 +85,90 @@ struct igc_hw {
 	u8 revision_id;
 };
 
+/* Statistics counters collected by the MAC */
+struct igc_hw_stats {
+	u64 crcerrs;
+	u64 algnerrc;
+	u64 symerrs;
+	u64 rxerrc;
+	u64 mpc;
+	u64 scc;
+	u64 ecol;
+	u64 mcc;
+	u64 latecol;
+	u64 colc;
+	u64 dc;
+	u64 tncrs;
+	u64 sec;
+	u64 cexterr;
+	u64 rlec;
+	u64 xonrxc;
+	u64 xontxc;
+	u64 xoffrxc;
+	u64 xofftxc;
+	u64 fcruc;
+	u64 prc64;
+	u64 prc127;
+	u64 prc255;
+	u64 prc511;
+	u64 prc1023;
+	u64 prc1522;
+	u64 gprc;
+	u64 bprc;
+	u64 mprc;
+	u64 gptc;
+	u64 gorc;
+	u64 gotc;
+	u64 rnbc;
+	u64 ruc;
+	u64 rfc;
+	u64 roc;
+	u64 rjc;
+	u64 mgprc;
+	u64 mgpdc;
+	u64 mgptc;
+	u64 tor;
+	u64 tot;
+	u64 tpr;
+	u64 tpt;
+	u64 ptc64;
+	u64 ptc127;
+	u64 ptc255;
+	u64 ptc511;
+	u64 ptc1023;
+	u64 ptc1522;
+	u64 mptc;
+	u64 bptc;
+	u64 tsctc;
+	u64 tsctfc;
+	u64 iac;
+	u64 icrxptc;
+	u64 icrxatc;
+	u64 ictxptc;
+	u64 ictxatc;
+	u64 ictxqec;
+	u64 ictxqmtc;
+	u64 icrxdmtc;
+	u64 icrxoc;
+	u64 cbtmpc;
+	u64 htdpmc;
+	u64 cbrdpc;
+	u64 cbrmpc;
+	u64 rpthc;
+	u64 hgptc;
+	u64 htcbdpc;
+	u64 hgorc;
+	u64 hgotc;
+	u64 lenerrs;
+	u64 scvpc;
+	u64 hrmpc;
+	u64 doosync;
+	u64 o2bgptc;
+	u64 o2bspc;
+	u64 b2ospc;
+	u64 b2ogprc;
+};
+
 s32  igc_read_pcie_cap_reg(struct igc_hw *hw, u32 reg, u16 *value);
 s32  igc_write_pcie_cap_reg(struct igc_hw *hw, u32 reg, u16 *value);
 void igc_read_pci_cfg(struct igc_hw *hw, u32 reg, u16 *value);

drivers/net/ethernet/intel/igc/igc_main.c

@@ -41,6 +41,22 @@ static int igc_sw_init(struct igc_adapter *);
 static void igc_configure(struct igc_adapter *adapter);
 static void igc_power_down_link(struct igc_adapter *adapter);
 static void igc_set_default_mac_filter(struct igc_adapter *adapter);
+static void igc_write_itr(struct igc_q_vector *q_vector);
+static void igc_assign_vector(struct igc_q_vector *q_vector, int msix_vector);
+static void igc_free_q_vector(struct igc_adapter *adapter, int v_idx);
+static void igc_set_interrupt_capability(struct igc_adapter *adapter,
+					 bool msix);
+static void igc_free_q_vectors(struct igc_adapter *adapter);
+static void igc_irq_disable(struct igc_adapter *adapter);
+static void igc_irq_enable(struct igc_adapter *adapter);
+static void igc_configure_msix(struct igc_adapter *adapter);
+
+enum latency_range {
+	lowest_latency = 0,
+	low_latency = 1,
+	bulk_latency = 2,
+	latency_invalid = 255
+};
 
 static void igc_reset(struct igc_adapter *adapter)
 {
@@ -154,6 +170,7 @@ static int igc_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd)
  */
 static void igc_up(struct igc_adapter *adapter)
 {
+	struct igc_hw *hw = &adapter->hw;
 	int i = 0;
 
 	/* hardware has been reset, we need to reload some things */
@@ -163,6 +180,15 @@ static void igc_up(struct igc_adapter *adapter)
 
 	for (i = 0; i < adapter->num_q_vectors; i++)
 		napi_enable(&adapter->q_vector[i]->napi);
+
+	if (adapter->msix_entries)
+		igc_configure_msix(adapter);
+	else
+		igc_assign_vector(adapter->q_vector[0], 0);
+
+	/* Clear any pending interrupts. */
+	rd32(IGC_ICR);
+	igc_irq_enable(adapter);
 }
 
 /**
@@ -309,6 +335,958 @@ static void igc_set_default_mac_filter(struct igc_adapter *adapter)
 	igc_rar_set_index(adapter, 0);
 }
 
+/**
+ * igc_msix_other - msix other interrupt handler
+ * @irq: interrupt number
+ * @data: pointer to a q_vector
+ */
+static irqreturn_t igc_msix_other(int irq, void *data)
+{
+	struct igc_adapter *adapter = data;
+	struct igc_hw *hw = &adapter->hw;
+	u32 icr = rd32(IGC_ICR);
+
+	/* reading ICR causes bit 31 of EICR to be cleared */
+	if (icr & IGC_ICR_DRSTA)
+		schedule_work(&adapter->reset_task);
+
+	if (icr & IGC_ICR_DOUTSYNC) {
+		/* HW is reporting DMA is out of sync */
+		adapter->stats.doosync++;
+	}
+
+	if (icr & IGC_ICR_LSC) {
+		hw->mac.get_link_status = 1;
+		/* guard against interrupt when we're going down */
+		if (!test_bit(__IGC_DOWN, &adapter->state))
+			mod_timer(&adapter->watchdog_timer, jiffies + 1);
+	}
+
+	wr32(IGC_EIMS, adapter->eims_other);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * igc_write_ivar - configure ivar for given MSI-X vector
+ * @hw: pointer to the HW structure
+ * @msix_vector: vector number we are allocating to a given ring
+ * @index: row index of IVAR register to write within IVAR table
+ * @offset: column offset of in IVAR, should be multiple of 8
+ *
+ * The IVAR table consists of 2 columns,
+ * each containing an cause allocation for an Rx and Tx ring, and a
+ * variable number of rows depending on the number of queues supported.
+ */
+static void igc_write_ivar(struct igc_hw *hw, int msix_vector,
+			   int index, int offset)
+{
+	u32 ivar = array_rd32(IGC_IVAR0, index);
+
+	/* clear any bits that are currently set */
+	ivar &= ~((u32)0xFF << offset);
+
+	/* write vector and valid bit */
+	ivar |= (msix_vector | IGC_IVAR_VALID) << offset;
+
+	array_wr32(IGC_IVAR0, index, ivar);
+}
+
+static void igc_assign_vector(struct igc_q_vector *q_vector, int msix_vector)
+{
+	struct igc_adapter *adapter = q_vector->adapter;
+	struct igc_hw *hw = &adapter->hw;
+	int rx_queue = IGC_N0_QUEUE;
+	int tx_queue = IGC_N0_QUEUE;
+
+	if (q_vector->rx.ring)
+		rx_queue = q_vector->rx.ring->reg_idx;
+	if (q_vector->tx.ring)
+		tx_queue = q_vector->tx.ring->reg_idx;
+
+	switch (hw->mac.type) {
+	case igc_i225:
+		if (rx_queue > IGC_N0_QUEUE)
+			igc_write_ivar(hw, msix_vector,
+				       rx_queue >> 1,
+				       (rx_queue & 0x1) << 4);
+		if (tx_queue > IGC_N0_QUEUE)
+			igc_write_ivar(hw, msix_vector,
+				       tx_queue >> 1,
+				       ((tx_queue & 0x1) << 4) + 8);
+		q_vector->eims_value = BIT(msix_vector);
+		break;
+	default:
+		WARN_ONCE(hw->mac.type != igc_i225, "Wrong MAC type\n");
+		break;
+	}
+
+	/* add q_vector eims value to global eims_enable_mask */
+	adapter->eims_enable_mask |= q_vector->eims_value;
+
+	/* configure q_vector to set itr on first interrupt */
+	q_vector->set_itr = 1;
+}
+
+/**
+ * igc_configure_msix - Configure MSI-X hardware
+ * @adapter: Pointer to adapter structure
+ *
+ * igc_configure_msix sets up the hardware to properly
+ * generate MSI-X interrupts.
+ */
+static void igc_configure_msix(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	int i, vector = 0;
+	u32 tmp;
+
+	adapter->eims_enable_mask = 0;
+
+	/* set vector for other causes, i.e. link changes */
+	switch (hw->mac.type) {
+	case igc_i225:
+		/* Turn on MSI-X capability first, or our settings
+		 * won't stick.  And it will take days to debug.
+		 */
+		wr32(IGC_GPIE, IGC_GPIE_MSIX_MODE |
+		     IGC_GPIE_PBA | IGC_GPIE_EIAME |
+		     IGC_GPIE_NSICR);
+
+		/* enable msix_other interrupt */
+		adapter->eims_other = BIT(vector);
+		tmp = (vector++ | IGC_IVAR_VALID) << 8;
+
+		wr32(IGC_IVAR_MISC, tmp);
+		break;
+	default:
+		/* do nothing, since nothing else supports MSI-X */
+		break;
+	} /* switch (hw->mac.type) */
+
+	adapter->eims_enable_mask |= adapter->eims_other;
+
+	for (i = 0; i < adapter->num_q_vectors; i++)
+		igc_assign_vector(adapter->q_vector[i], vector++);
+
+	wrfl();
+}
+
+static irqreturn_t igc_msix_ring(int irq, void *data)
+{
+	struct igc_q_vector *q_vector = data;
+
+	/* Write the ITR value calculated from the previous interrupt. */
+	igc_write_itr(q_vector);
+
+	napi_schedule(&q_vector->napi);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * igc_request_msix - Initialize MSI-X interrupts
+ * @adapter: Pointer to adapter structure
+ *
+ * igc_request_msix allocates MSI-X vectors and requests interrupts from the
+ * kernel.
+ */
+static int igc_request_msix(struct igc_adapter *adapter)
+{
+	int i = 0, err = 0, vector = 0, free_vector = 0;
+	struct net_device *netdev = adapter->netdev;
+
+	err = request_irq(adapter->msix_entries[vector].vector,
+			  &igc_msix_other, 0, netdev->name, adapter);
+	if (err)
+		goto err_out;
+
+	for (i = 0; i < adapter->num_q_vectors; i++) {
+		struct igc_q_vector *q_vector = adapter->q_vector[i];
+
+		vector++;
+
+		q_vector->itr_register = adapter->io_addr + IGC_EITR(vector);
+
+		if (q_vector->rx.ring && q_vector->tx.ring)
+			sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
+				q_vector->rx.ring->queue_index);
+		else if (q_vector->tx.ring)
+			sprintf(q_vector->name, "%s-tx-%u", netdev->name,
+				q_vector->tx.ring->queue_index);
+		else if (q_vector->rx.ring)
+			sprintf(q_vector->name, "%s-rx-%u", netdev->name,
+				q_vector->rx.ring->queue_index);
+		else
+			sprintf(q_vector->name, "%s-unused", netdev->name);
+
+		err = request_irq(adapter->msix_entries[vector].vector,
+				  igc_msix_ring, 0, q_vector->name,
+				  q_vector);
+		if (err)
+			goto err_free;
+	}
+
+	igc_configure_msix(adapter);
+	return 0;
+
+err_free:
+	/* free already assigned IRQs */
+	free_irq(adapter->msix_entries[free_vector++].vector, adapter);
+
+	vector--;
+	for (i = 0; i < vector; i++) {
+		free_irq(adapter->msix_entries[free_vector++].vector,
+			 adapter->q_vector[i]);
+	}
+err_out:
+	return err;
+}
+
+/**
+ * igc_reset_q_vector - Reset config for interrupt vector
+ * @adapter: board private structure to initialize
+ * @v_idx: Index of vector to be reset
+ *
+ * If NAPI is enabled it will delete any references to the
+ * NAPI struct. This is preparation for igc_free_q_vector.
+ */
+static void igc_reset_q_vector(struct igc_adapter *adapter, int v_idx)
+{
+	struct igc_q_vector *q_vector = adapter->q_vector[v_idx];
+
+	/* if we're coming from igc_set_interrupt_capability, the vectors are
+	 * not yet allocated
+	 */
+	if (!q_vector)
+		return;
+
+	if (q_vector->tx.ring)
+		adapter->tx_ring[q_vector->tx.ring->queue_index] = NULL;
+
+	if (q_vector->rx.ring)
+		adapter->rx_ring[q_vector->rx.ring->queue_index] = NULL;
+
+	netif_napi_del(&q_vector->napi);
+}
+
+static void igc_reset_interrupt_capability(struct igc_adapter *adapter)
+{
+	int v_idx = adapter->num_q_vectors;
+
+	if (adapter->msix_entries) {
+		pci_disable_msix(adapter->pdev);
+		kfree(adapter->msix_entries);
+		adapter->msix_entries = NULL;
+	} else if (adapter->flags & IGC_FLAG_HAS_MSI) {
+		pci_disable_msi(adapter->pdev);
+	}
+
+	while (v_idx--)
+		igc_reset_q_vector(adapter, v_idx);
+}
+
+/**
+ * igc_clear_interrupt_scheme - reset the device to a state of no interrupts
+ * @adapter: Pointer to adapter structure
+ *
+ * This function resets the device so that it has 0 rx queues, tx queues, and
+ * MSI-X interrupts allocated.
+ */
+static void igc_clear_interrupt_scheme(struct igc_adapter *adapter)
+{
+	igc_free_q_vectors(adapter);
+	igc_reset_interrupt_capability(adapter);
+}
+
+/**
+ * igc_free_q_vectors - Free memory allocated for interrupt vectors
+ * @adapter: board private structure to initialize
+ *
+ * This function frees the memory allocated to the q_vectors.  In addition if
+ * NAPI is enabled it will delete any references to the NAPI struct prior
+ * to freeing the q_vector.
+ */
+static void igc_free_q_vectors(struct igc_adapter *adapter)
+{
+	int v_idx = adapter->num_q_vectors;
+
+	adapter->num_tx_queues = 0;
+	adapter->num_rx_queues = 0;
+	adapter->num_q_vectors = 0;
+
+	while (v_idx--) {
+		igc_reset_q_vector(adapter, v_idx);
+		igc_free_q_vector(adapter, v_idx);
+	}
+}
+
+/**
+ * igc_free_q_vector - Free memory allocated for specific interrupt vector
+ * @adapter: board private structure to initialize
+ * @v_idx: Index of vector to be freed
+ *
+ * This function frees the memory allocated to the q_vector.
+ */
+static void igc_free_q_vector(struct igc_adapter *adapter, int v_idx)
+{
+	struct igc_q_vector *q_vector = adapter->q_vector[v_idx];
+
+	adapter->q_vector[v_idx] = NULL;
+
+	/* igc_get_stats64() might access the rings on this vector,
+	 * we must wait a grace period before freeing it.
+	 */
+	if (q_vector)
+		kfree_rcu(q_vector, rcu);
+}
+
+/**
+ * igc_update_ring_itr - update the dynamic ITR value based on packet size
+ * @q_vector: pointer to q_vector
+ *
+ * Stores a new ITR value based on strictly on packet size.  This
+ * algorithm is less sophisticated than that used in igc_update_itr,
+ * due to the difficulty of synchronizing statistics across multiple
+ * receive rings.  The divisors and thresholds used by this function
+ * were determined based on theoretical maximum wire speed and testing
+ * data, in order to minimize response time while increasing bulk
+ * throughput.
+ * NOTE: This function is called only when operating in a multiqueue
+ * receive environment.
+ */
+static void igc_update_ring_itr(struct igc_q_vector *q_vector)
+{
+	struct igc_adapter *adapter = q_vector->adapter;
+	int new_val = q_vector->itr_val;
+	int avg_wire_size = 0;
+	unsigned int packets;
+
+	/* For non-gigabit speeds, just fix the interrupt rate at 4000
+	 * ints/sec - ITR timer value of 120 ticks.
+	 */
+	switch (adapter->link_speed) {
+	case SPEED_10:
+	case SPEED_100:
+		new_val = IGC_4K_ITR;
+		goto set_itr_val;
+	default:
+		break;
+	}
+
+	packets = q_vector->rx.total_packets;
+	if (packets)
+		avg_wire_size = q_vector->rx.total_bytes / packets;
+
+	packets = q_vector->tx.total_packets;
+	if (packets)
+		avg_wire_size = max_t(u32, avg_wire_size,
+				      q_vector->tx.total_bytes / packets);
+
+	/* if avg_wire_size isn't set no work was done */
+	if (!avg_wire_size)
+		goto clear_counts;
+
+	/* Add 24 bytes to size to account for CRC, preamble, and gap */
+	avg_wire_size += 24;
+
+	/* Don't starve jumbo frames */
+	avg_wire_size = min(avg_wire_size, 3000);
+
+	/* Give a little boost to mid-size frames */
+	if (avg_wire_size > 300 && avg_wire_size < 1200)
+		new_val = avg_wire_size / 3;
+	else
+		new_val = avg_wire_size / 2;
+
+	/* conservative mode (itr 3) eliminates the lowest_latency setting */
+	if (new_val < IGC_20K_ITR &&
+	    ((q_vector->rx.ring && adapter->rx_itr_setting == 3) ||
+	    (!q_vector->rx.ring && adapter->tx_itr_setting == 3)))
+		new_val = IGC_20K_ITR;
+
+set_itr_val:
+	if (new_val != q_vector->itr_val) {
+		q_vector->itr_val = new_val;
+		q_vector->set_itr = 1;
+	}
+clear_counts:
+	q_vector->rx.total_bytes = 0;
+	q_vector->rx.total_packets = 0;
+	q_vector->tx.total_bytes = 0;
+	q_vector->tx.total_packets = 0;
+}
+
+/**
+ * igc_update_itr - update the dynamic ITR value based on statistics
+ * @q_vector: pointer to q_vector
+ * @ring_container: ring info to update the itr for
+ *
+ * Stores a new ITR value based on packets and byte
+ * counts during the last interrupt.  The advantage of per interrupt
+ * computation is faster updates and more accurate ITR for the current
+ * traffic pattern.  Constants in this function were computed
+ * based on theoretical maximum wire speed and thresholds were set based
+ * on testing data as well as attempting to minimize response time
+ * while increasing bulk throughput.
+ * NOTE: These calculations are only valid when operating in a single-
+ * queue environment.
+ */
+static void igc_update_itr(struct igc_q_vector *q_vector,
+			   struct igc_ring_container *ring_container)
+{
+	unsigned int packets = ring_container->total_packets;
+	unsigned int bytes = ring_container->total_bytes;
+	u8 itrval = ring_container->itr;
+
+	/* no packets, exit with status unchanged */
+	if (packets == 0)
+		return;
+
+	switch (itrval) {
+	case lowest_latency:
+		/* handle TSO and jumbo frames */
+		if (bytes / packets > 8000)
+			itrval = bulk_latency;
+		else if ((packets < 5) && (bytes > 512))
+			itrval = low_latency;
+		break;
+	case low_latency:  /* 50 usec aka 20000 ints/s */
+		if (bytes > 10000) {
+			/* this if handles the TSO accounting */
+			if (bytes / packets > 8000)
+				itrval = bulk_latency;
+			else if ((packets < 10) || ((bytes / packets) > 1200))
+				itrval = bulk_latency;
+			else if ((packets > 35))
+				itrval = lowest_latency;
+		} else if (bytes / packets > 2000) {
+			itrval = bulk_latency;
+		} else if (packets <= 2 && bytes < 512) {
+			itrval = lowest_latency;
+		}
+		break;
+	case bulk_latency: /* 250 usec aka 4000 ints/s */
+		if (bytes > 25000) {
+			if (packets > 35)
+				itrval = low_latency;
+		} else if (bytes < 1500) {
+			itrval = low_latency;
+		}
+		break;
+	}
+
+	/* clear work counters since we have the values we need */
+	ring_container->total_bytes = 0;
+	ring_container->total_packets = 0;
+
+	/* write updated itr to ring container */
+	ring_container->itr = itrval;
+}
+
+static void igc_set_itr(struct igc_q_vector *q_vector)
+{
+	struct igc_adapter *adapter = q_vector->adapter;
+	u32 new_itr = q_vector->itr_val;
+	u8 current_itr = 0;
+
+	/* for non-gigabit speeds, just fix the interrupt rate at 4000 */
+	switch (adapter->link_speed) {
+	case SPEED_10:
+	case SPEED_100:
+		current_itr = 0;
+		new_itr = IGC_4K_ITR;
+		goto set_itr_now;
+	default:
+		break;
+	}
+
+	igc_update_itr(q_vector, &q_vector->tx);
+	igc_update_itr(q_vector, &q_vector->rx);
+
+	current_itr = max(q_vector->rx.itr, q_vector->tx.itr);
+
+	/* conservative mode (itr 3) eliminates the lowest_latency setting */
+	if (current_itr == lowest_latency &&
+	    ((q_vector->rx.ring && adapter->rx_itr_setting == 3) ||
+	    (!q_vector->rx.ring && adapter->tx_itr_setting == 3)))
+		current_itr = low_latency;
+
+	switch (current_itr) {
+	/* counts and packets in update_itr are dependent on these numbers */
+	case lowest_latency:
+		new_itr = IGC_70K_ITR; /* 70,000 ints/sec */
+		break;
+	case low_latency:
+		new_itr = IGC_20K_ITR; /* 20,000 ints/sec */
+		break;
+	case bulk_latency:
+		new_itr = IGC_4K_ITR;  /* 4,000 ints/sec */
+		break;
+	default:
+		break;
+	}
+
+set_itr_now:
+	if (new_itr != q_vector->itr_val) {
+		/* this attempts to bias the interrupt rate towards Bulk
+		 * by adding intermediate steps when interrupt rate is
+		 * increasing
+		 */
+		new_itr = new_itr > q_vector->itr_val ?
+			  max((new_itr * q_vector->itr_val) /
+			  (new_itr + (q_vector->itr_val >> 2)),
+			  new_itr) : new_itr;
+		/* Don't write the value here; it resets the adapter's
+		 * internal timer, and causes us to delay far longer than
+		 * we should between interrupts.  Instead, we write the ITR
+		 * value at the beginning of the next interrupt so the timing
+		 * ends up being correct.
+		 */
+		q_vector->itr_val = new_itr;
+		q_vector->set_itr = 1;
+	}
+}
+
+static void igc_ring_irq_enable(struct igc_q_vector *q_vector)
+{
+	struct igc_adapter *adapter = q_vector->adapter;
+	struct igc_hw *hw = &adapter->hw;
+
+	if ((q_vector->rx.ring && (adapter->rx_itr_setting & 3)) ||
+	    (!q_vector->rx.ring && (adapter->tx_itr_setting & 3))) {
+		if (adapter->num_q_vectors == 1)
+			igc_set_itr(q_vector);
+		else
+			igc_update_ring_itr(q_vector);
+	}
+
+	if (!test_bit(__IGC_DOWN, &adapter->state)) {
+		if (adapter->msix_entries)
+			wr32(IGC_EIMS, q_vector->eims_value);
+		else
+			igc_irq_enable(adapter);
+	}
+}
+
+/**
+ * igc_poll - NAPI Rx polling callback
+ * @napi: napi polling structure
+ * @budget: count of how many packets we should handle
+ */
+static int igc_poll(struct napi_struct *napi, int budget)
+{
+	struct igc_q_vector *q_vector = container_of(napi,
+						     struct igc_q_vector,
+						     napi);
+	bool clean_complete = true;
+	int work_done = 0;
+	int cleaned = 0;
+
+	if (q_vector->rx.ring) {
+		work_done += cleaned;
+		if (cleaned >= budget)
+			clean_complete = false;
+	}
+
+	/* If all work not completed, return budget and keep polling */
+	if (!clean_complete)
+		return budget;
+
+	/* If not enough Rx work done, exit the polling mode */
+	napi_complete_done(napi, work_done);
+	igc_ring_irq_enable(q_vector);
+
+	return 0;
+}
+
+/**
+ * igc_set_interrupt_capability - set MSI or MSI-X if supported
+ * @adapter: Pointer to adapter structure
+ *
+ * Attempt to configure interrupts using the best available
+ * capabilities of the hardware and kernel.
+ */
+static void igc_set_interrupt_capability(struct igc_adapter *adapter,
+					 bool msix)
+{
+	int numvecs, i;
+	int err;
+
+	if (!msix)
+		goto msi_only;
+	adapter->flags |= IGC_FLAG_HAS_MSIX;
+
+	/* Number of supported queues. */
+	adapter->num_rx_queues = adapter->rss_queues;
+
+	adapter->num_tx_queues = adapter->rss_queues;
+
+	/* start with one vector for every Rx queue */
+	numvecs = adapter->num_rx_queues;
+
+	/* if Tx handler is separate add 1 for every Tx queue */
+	if (!(adapter->flags & IGC_FLAG_QUEUE_PAIRS))
+		numvecs += adapter->num_tx_queues;
+
+	/* store the number of vectors reserved for queues */
+	adapter->num_q_vectors = numvecs;
+
+	/* add 1 vector for link status interrupts */
+	numvecs++;
+
+	adapter->msix_entries = kcalloc(numvecs, sizeof(struct msix_entry),
+					GFP_KERNEL);
+
+	if (!adapter->msix_entries)
+		return;
+
+	/* populate entry values */
+	for (i = 0; i < numvecs; i++)
+		adapter->msix_entries[i].entry = i;
+
+	err = pci_enable_msix_range(adapter->pdev,
+				    adapter->msix_entries,
+				    numvecs,
+				    numvecs);
+	if (err > 0)
+		return;
+
+	kfree(adapter->msix_entries);
+	adapter->msix_entries = NULL;
+
+	igc_reset_interrupt_capability(adapter);
+
+msi_only:
+	adapter->flags &= ~IGC_FLAG_HAS_MSIX;
+
+	adapter->rss_queues = 1;
+	adapter->flags |= IGC_FLAG_QUEUE_PAIRS;
+	adapter->num_rx_queues = 1;
+	adapter->num_tx_queues = 1;
+	adapter->num_q_vectors = 1;
+	if (!pci_enable_msi(adapter->pdev))
+		adapter->flags |= IGC_FLAG_HAS_MSI;
+}
+
+static void igc_add_ring(struct igc_ring *ring,
+			 struct igc_ring_container *head)
+{
+	head->ring = ring;
+	head->count++;
+}
+
+/**
+ * igc_alloc_q_vector - Allocate memory for a single interrupt vector
+ * @adapter: board private structure to initialize
+ * @v_count: q_vectors allocated on adapter, used for ring interleaving
+ * @v_idx: index of vector in adapter struct
+ * @txr_count: total number of Tx rings to allocate
+ * @txr_idx: index of first Tx ring to allocate
+ * @rxr_count: total number of Rx rings to allocate
+ * @rxr_idx: index of first Rx ring to allocate
+ *
+ * We allocate one q_vector.  If allocation fails we return -ENOMEM.
+ */
+static int igc_alloc_q_vector(struct igc_adapter *adapter,
+			      unsigned int v_count, unsigned int v_idx,
+			      unsigned int txr_count, unsigned int txr_idx,
+			      unsigned int rxr_count, unsigned int rxr_idx)
+{
+	struct igc_q_vector *q_vector;
+	struct igc_ring *ring;
+	int ring_count, size;
+
+	/* igc only supports 1 Tx and/or 1 Rx queue per vector */
+	if (txr_count > 1 || rxr_count > 1)
+		return -ENOMEM;
+
+	ring_count = txr_count + rxr_count;
+	size = sizeof(struct igc_q_vector) +
+		(sizeof(struct igc_ring) * ring_count);
+
+	/* allocate q_vector and rings */
+	q_vector = adapter->q_vector[v_idx];
+	if (!q_vector)
+		q_vector = kzalloc(size, GFP_KERNEL);
+	else
+		memset(q_vector, 0, size);
+	if (!q_vector)
+		return -ENOMEM;
+
+	/* initialize NAPI */
+	netif_napi_add(adapter->netdev, &q_vector->napi,
+		       igc_poll, 64);
+
+	/* tie q_vector and adapter together */
+	adapter->q_vector[v_idx] = q_vector;
+	q_vector->adapter = adapter;
+
+	/* initialize work limits */
+	q_vector->tx.work_limit = adapter->tx_work_limit;
+
+	/* initialize ITR configuration */
+	q_vector->itr_register = adapter->io_addr + IGC_EITR(0);
+	q_vector->itr_val = IGC_START_ITR;
+
+	/* initialize pointer to rings */
+	ring = q_vector->ring;
+
+	/* initialize ITR */
+	if (rxr_count) {
+		/* rx or rx/tx vector */
+		if (!adapter->rx_itr_setting || adapter->rx_itr_setting > 3)
+			q_vector->itr_val = adapter->rx_itr_setting;
+	} else {
+		/* tx only vector */
+		if (!adapter->tx_itr_setting || adapter->tx_itr_setting > 3)
+			q_vector->itr_val = adapter->tx_itr_setting;
+	}
+
+	if (txr_count) {
+		/* assign generic ring traits */
+		ring->dev = &adapter->pdev->dev;
+		ring->netdev = adapter->netdev;
+
+		/* configure backlink on ring */
+		ring->q_vector = q_vector;
+
+		/* update q_vector Tx values */
+		igc_add_ring(ring, &q_vector->tx);
+
+		/* apply Tx specific ring traits */
+		ring->count = adapter->tx_ring_count;
+		ring->queue_index = txr_idx;
+
+		/* assign ring to adapter */
+		adapter->tx_ring[txr_idx] = ring;
+
+		/* push pointer to next ring */
+		ring++;
+	}
+
+	if (rxr_count) {
+		/* assign generic ring traits */
+		ring->dev = &adapter->pdev->dev;
+		ring->netdev = adapter->netdev;
+
+		/* configure backlink on ring */
+		ring->q_vector = q_vector;
+
+		/* update q_vector Rx values */
+		igc_add_ring(ring, &q_vector->rx);
+
+		/* apply Rx specific ring traits */
+		ring->count = adapter->rx_ring_count;
+		ring->queue_index = rxr_idx;
+
+		/* assign ring to adapter */
+		adapter->rx_ring[rxr_idx] = ring;
+	}
+
+	return 0;
+}
+
+/**
+ * igc_alloc_q_vectors - Allocate memory for interrupt vectors
+ * @adapter: board private structure to initialize
+ *
+ * We allocate one q_vector per queue interrupt.  If allocation fails we
+ * return -ENOMEM.
+ */
+static int igc_alloc_q_vectors(struct igc_adapter *adapter)
+{
+	int rxr_remaining = adapter->num_rx_queues;
+	int txr_remaining = adapter->num_tx_queues;
+	int rxr_idx = 0, txr_idx = 0, v_idx = 0;
+	int q_vectors = adapter->num_q_vectors;
+	int err;
+
+	if (q_vectors >= (rxr_remaining + txr_remaining)) {
+		for (; rxr_remaining; v_idx++) {
+			err = igc_alloc_q_vector(adapter, q_vectors, v_idx,
+						 0, 0, 1, rxr_idx);
+
+			if (err)
+				goto err_out;
+
+			/* update counts and index */
+			rxr_remaining--;
+			rxr_idx++;
+		}
+	}
+
+	for (; v_idx < q_vectors; v_idx++) {
+		int rqpv = DIV_ROUND_UP(rxr_remaining, q_vectors - v_idx);
+		int tqpv = DIV_ROUND_UP(txr_remaining, q_vectors - v_idx);
+
+		err = igc_alloc_q_vector(adapter, q_vectors, v_idx,
+					 tqpv, txr_idx, rqpv, rxr_idx);
+
+		if (err)
+			goto err_out;
+
+		/* update counts and index */
+		rxr_remaining -= rqpv;
+		txr_remaining -= tqpv;
+		rxr_idx++;
+		txr_idx++;
+	}
+
+	return 0;
+
+err_out:
+	adapter->num_tx_queues = 0;
+	adapter->num_rx_queues = 0;
+	adapter->num_q_vectors = 0;
+
+	while (v_idx--)
+		igc_free_q_vector(adapter, v_idx);
+
+	return -ENOMEM;
+}
+
+/**
+ * igc_init_interrupt_scheme - initialize interrupts, allocate queues/vectors
+ * @adapter: Pointer to adapter structure
+ *
+ * This function initializes the interrupts and allocates all of the queues.
+ */
+static int igc_init_interrupt_scheme(struct igc_adapter *adapter, bool msix)
+{
+	struct pci_dev *pdev = adapter->pdev;
+	int err = 0;
+
+	igc_set_interrupt_capability(adapter, msix);
+
+	err = igc_alloc_q_vectors(adapter);
+	if (err) {
+		dev_err(&pdev->dev, "Unable to allocate memory for vectors\n");
+		goto err_alloc_q_vectors;
+	}
+
+	return 0;
+
+err_alloc_q_vectors:
+	igc_reset_interrupt_capability(adapter);
+	return err;
+}
+
+static void igc_free_irq(struct igc_adapter *adapter)
+{
+	if (adapter->msix_entries) {
+		int vector = 0, i;
+
+		free_irq(adapter->msix_entries[vector++].vector, adapter);
+
+		for (i = 0; i < adapter->num_q_vectors; i++)
+			free_irq(adapter->msix_entries[vector++].vector,
+				 adapter->q_vector[i]);
+	} else {
+		free_irq(adapter->pdev->irq, adapter);
+	}
+}
+
+/**
+ * igc_irq_disable - Mask off interrupt generation on the NIC
+ * @adapter: board private structure
+ */
+static void igc_irq_disable(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+
+	if (adapter->msix_entries) {
+		u32 regval = rd32(IGC_EIAM);
+
+		wr32(IGC_EIAM, regval & ~adapter->eims_enable_mask);
+		wr32(IGC_EIMC, adapter->eims_enable_mask);
+		regval = rd32(IGC_EIAC);
+		wr32(IGC_EIAC, regval & ~adapter->eims_enable_mask);
+	}
+
+	wr32(IGC_IAM, 0);
+	wr32(IGC_IMC, ~0);
+	wrfl();
+
+	if (adapter->msix_entries) {
+		int vector = 0, i;
+
+		synchronize_irq(adapter->msix_entries[vector++].vector);
+
+		for (i = 0; i < adapter->num_q_vectors; i++)
+			synchronize_irq(adapter->msix_entries[vector++].vector);
+	} else {
+		synchronize_irq(adapter->pdev->irq);
+	}
+}
+
+/**
+ * igc_irq_enable - Enable default interrupt generation settings
+ * @adapter: board private structure
+ */
+static void igc_irq_enable(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+
+	if (adapter->msix_entries) {
+		u32 ims = IGC_IMS_LSC | IGC_IMS_DOUTSYNC | IGC_IMS_DRSTA;
+		u32 regval = rd32(IGC_EIAC);
+
+		wr32(IGC_EIAC, regval | adapter->eims_enable_mask);
+		regval = rd32(IGC_EIAM);
+		wr32(IGC_EIAM, regval | adapter->eims_enable_mask);
+		wr32(IGC_EIMS, adapter->eims_enable_mask);
+		wr32(IGC_IMS, ims);
+	} else {
+		wr32(IGC_IMS, IMS_ENABLE_MASK | IGC_IMS_DRSTA);
+		wr32(IGC_IAM, IMS_ENABLE_MASK | IGC_IMS_DRSTA);
+	}
+}
+
+/**
+ * igc_request_irq - initialize interrupts
+ * @adapter: Pointer to adapter structure
+ *
+ * Attempts to configure interrupts using the best available
+ * capabilities of the hardware and kernel.
+ */
+static int igc_request_irq(struct igc_adapter *adapter)
+{
+	int err = 0;
+
+	if (adapter->flags & IGC_FLAG_HAS_MSIX) {
+		err = igc_request_msix(adapter);
+		if (!err)
+			goto request_done;
+		/* fall back to MSI */
+
+		igc_clear_interrupt_scheme(adapter);
+		err = igc_init_interrupt_scheme(adapter, false);
+		if (err)
+			goto request_done;
+		igc_configure(adapter);
+	}
+
+request_done:
+	return err;
+}
+
+static void igc_write_itr(struct igc_q_vector *q_vector)
+{
+	u32 itr_val = q_vector->itr_val & IGC_QVECTOR_MASK;
+
+	if (!q_vector->set_itr)
+		return;
+
+	if (!itr_val)
+		itr_val = IGC_ITR_VAL_MASK;
+
+	itr_val |= IGC_EITR_CNT_IGNR;
+
+	writel(itr_val, q_vector->itr_register);
+	q_vector->set_itr = 0;
+}
+
 /**
  * igc_open - Called when a network interface is made active
  * @netdev: network interface device structure
@@ -325,6 +1303,7 @@ static int __igc_open(struct net_device *netdev, bool resuming)
 {
 	struct igc_adapter *adapter = netdev_priv(netdev);
 	struct igc_hw *hw = &adapter->hw;
+	int err = 0;
 	int i = 0;
 
 	/* disallow open during test */
@@ -340,15 +1319,40 @@ static int __igc_open(struct net_device *netdev, bool resuming)
 
 	igc_configure(adapter);
 
+	err = igc_request_irq(adapter);
+	if (err)
+		goto err_req_irq;
+
+	/* Notify the stack of the actual queue counts. */
+	netif_set_real_num_tx_queues(netdev, adapter->num_tx_queues);
+	if (err)
+		goto err_set_queues;
+
+	err = netif_set_real_num_rx_queues(netdev, adapter->num_rx_queues);
+	if (err)
+		goto err_set_queues;
+
 	clear_bit(__IGC_DOWN, &adapter->state);
 
 	for (i = 0; i < adapter->num_q_vectors; i++)
 		napi_enable(&adapter->q_vector[i]->napi);
 
+	/* Clear any pending interrupts. */
+	rd32(IGC_ICR);
+	igc_irq_enable(adapter);
+
 	/* start the watchdog. */
 	hw->mac.get_link_status = 1;
 
 	return IGC_SUCCESS;
+
+err_set_queues:
+	igc_free_irq(adapter);
+err_req_irq:
+	igc_release_hw_control(adapter);
+	igc_power_down_link(adapter);
+
+	return err;
 }
 
 static int igc_open(struct net_device *netdev)
@@ -377,6 +1381,8 @@ static int __igc_close(struct net_device *netdev, bool suspending)
 
 	igc_release_hw_control(adapter);
 
+	igc_free_irq(adapter);
+
 	return 0;
 }
 
@@ -595,6 +1601,8 @@ static int igc_probe(struct pci_dev *pdev,
 err_register:
 	igc_release_hw_control(adapter);
 err_sw_init:
+	igc_clear_interrupt_scheme(adapter);
+	iounmap(adapter->io_addr);
 err_ioremap:
 	free_netdev(netdev);
 err_alloc_etherdev:
@@ -672,6 +1680,14 @@ static int igc_sw_init(struct igc_adapter *adapter)
 	adapter->max_frame_size = netdev->mtu + ETH_HLEN + ETH_FCS_LEN +
 					VLAN_HLEN;
 
+	if (igc_init_interrupt_scheme(adapter, true)) {
+		dev_err(&pdev->dev, "Unable to allocate memory for queues\n");
+		return -ENOMEM;
+	}
+
+	/* Explicitly disable IRQ since the NIC can be in any state. */
+	igc_irq_disable(adapter);
+
 	set_bit(__IGC_DOWN, &adapter->state);
 
 	return 0;