// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2013 - 2018 Intel Corporation. */

#include <linux/bitfield.h>
#include <linux/net/intel/libie/rx.h>
#include <linux/prefetch.h>

#include "iavf.h"
#include "iavf_trace.h"
#include "iavf_prototype.h"
#include "iavf_ptp.h"

/**
 * iavf_is_descriptor_done - tests DD bit in Rx descriptor
 * @qw1: quad word 1 from descriptor to get Descriptor Done field from
 * @flex: is the descriptor flex or legacy
 *
 * This function tests the descriptor done bit in specified descriptor. Because
 * there are two types of descriptors (legacy and flex) the parameter rx_ring
 * is used to distinguish.
 *
 * Return: true or false based on the state of DD bit in Rx descriptor.
 */
static bool iavf_is_descriptor_done(u64 qw1, bool flex)
{
        if (flex)
                return FIELD_GET(IAVF_RXD_FLEX_DD_M, qw1);
        else
                return FIELD_GET(IAVF_RXD_LEGACY_DD_M, qw1);
}

static __le64 build_ctob(u32 td_cmd, u32 td_offset, unsigned int size,
                         u32 td_tag)
{
        return cpu_to_le64(IAVF_TX_DESC_DTYPE_DATA |
                           ((u64)td_cmd  << IAVF_TXD_QW1_CMD_SHIFT) |
                           ((u64)td_offset << IAVF_TXD_QW1_OFFSET_SHIFT) |
                           ((u64)size  << IAVF_TXD_QW1_TX_BUF_SZ_SHIFT) |
                           ((u64)td_tag  << IAVF_TXD_QW1_L2TAG1_SHIFT));
}

#define IAVF_TXD_CMD (IAVF_TX_DESC_CMD_EOP | IAVF_TX_DESC_CMD_RS)

/**
 * iavf_unmap_and_free_tx_resource - Release a Tx buffer
 * @ring:      the ring that owns the buffer
 * @tx_buffer: the buffer to free
 **/
static void iavf_unmap_and_free_tx_resource(struct iavf_ring *ring,
                                            struct iavf_tx_buffer *tx_buffer)
{
        if (tx_buffer->skb) {
                if (tx_buffer->tx_flags & IAVF_TX_FLAGS_FD_SB)
                        kfree(tx_buffer->raw_buf);
                else
                        dev_kfree_skb_any(tx_buffer->skb);
                if (dma_unmap_len(tx_buffer, len))
                        dma_unmap_single(ring->dev,
                                         dma_unmap_addr(tx_buffer, dma),
                                         dma_unmap_len(tx_buffer, len),
                                         DMA_TO_DEVICE);
        } else if (dma_unmap_len(tx_buffer, len)) {
                dma_unmap_page(ring->dev,
                               dma_unmap_addr(tx_buffer, dma),
                               dma_unmap_len(tx_buffer, len),
                               DMA_TO_DEVICE);
        }

        tx_buffer->next_to_watch = NULL;
        tx_buffer->skb = NULL;
        dma_unmap_len_set(tx_buffer, len, 0);
        /* tx_buffer must be completely set up in the transmit path */
}

/**
 * iavf_clean_tx_ring - Free any empty Tx buffers
 * @tx_ring: ring to be cleaned
 **/
static void iavf_clean_tx_ring(struct iavf_ring *tx_ring)
{
        unsigned long bi_size;
        u16 i;

        /* ring already cleared, nothing to do */
        if (!tx_ring->tx_bi)
                return;

        /* Free all the Tx ring sk_buffs */
        for (i = 0; i < tx_ring->count; i++)
                iavf_unmap_and_free_tx_resource(tx_ring, &tx_ring->tx_bi[i]);

        bi_size = sizeof(struct iavf_tx_buffer) * tx_ring->count;
        memset(tx_ring->tx_bi, 0, bi_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;

        if (!tx_ring->netdev)
                return;

        /* cleanup Tx queue statistics */
        netdev_tx_reset_queue(txring_txq(tx_ring));
}

/**
 * iavf_free_tx_resources - Free Tx resources per queue
 * @tx_ring: Tx descriptor ring for a specific queue
 *
 * Free all transmit software resources
 **/
void iavf_free_tx_resources(struct iavf_ring *tx_ring)
{
        iavf_clean_tx_ring(tx_ring);
        kfree(tx_ring->tx_bi);
        tx_ring->tx_bi = NULL;

        if (tx_ring->desc) {
                dma_free_coherent(tx_ring->dev, tx_ring->size,
                                  tx_ring->desc, tx_ring->dma);
                tx_ring->desc = NULL;
        }
}

/**
 * iavf_get_tx_pending - how many Tx descriptors not processed
 * @ring: the ring of descriptors
 * @in_sw: is tx_pending being checked in SW or HW
 *
 * Since there is no access to the ring head register
 * in XL710, we need to use our local copies
 **/
static u32 iavf_get_tx_pending(struct iavf_ring *ring, bool in_sw)
{
        u32 head, tail;

        /* underlying hardware might not allow access and/or always return
         * 0 for the head/tail registers so just use the cached values
         */
        head = ring->next_to_clean;
        tail = ring->next_to_use;

        if (head != tail)
                return (head < tail) ?
                        tail - head : (tail + ring->count - head);

        return 0;
}

/**
 * iavf_force_wb - Issue SW Interrupt so HW does a wb
 * @vsi: the VSI we care about
 * @q_vector: the vector on which to force writeback
 **/
static void iavf_force_wb(struct iavf_vsi *vsi, struct iavf_q_vector *q_vector)
{
        u32 val = IAVF_VFINT_DYN_CTLN1_INTENA_MASK |
                  IAVF_VFINT_DYN_CTLN1_ITR_INDX_MASK | /* set noitr */
                  IAVF_VFINT_DYN_CTLN1_SWINT_TRIG_MASK |
                  IAVF_VFINT_DYN_CTLN1_SW_ITR_INDX_ENA_MASK
                  /* allow 00 to be written to the index */;

        wr32(&vsi->back->hw,
             IAVF_VFINT_DYN_CTLN1(q_vector->reg_idx),
             val);
}

/**
 * iavf_detect_recover_hung - Function to detect and recover hung_queues
 * @vsi:  pointer to vsi struct with tx queues
 *
 * VSI has netdev and netdev has TX queues. This function is to check each of
 * those TX queues if they are hung, trigger recovery by issuing SW interrupt.
 **/
void iavf_detect_recover_hung(struct iavf_vsi *vsi)
{
        struct iavf_ring *tx_ring = NULL;
        struct net_device *netdev;
        unsigned int i;
        int packets;

        if (!vsi)
                return;

        if (test_bit(__IAVF_VSI_DOWN, vsi->state))
                return;

        netdev = vsi->netdev;
        if (!netdev)
                return;

        if (!netif_carrier_ok(netdev))
                return;

        for (i = 0; i < vsi->back->num_active_queues; i++) {
                tx_ring = &vsi->back->tx_rings[i];
                if (tx_ring && tx_ring->desc) {
                        /* If packet counter has not changed the queue is
                         * likely stalled, so force an interrupt for this
                         * queue.
                         *
                         * prev_pkt_ctr would be negative if there was no
                         * pending work.
                         */
                        packets = tx_ring->stats.packets & INT_MAX;
                        if (tx_ring->prev_pkt_ctr == packets) {
                                iavf_force_wb(vsi, tx_ring->q_vector);
                                continue;
                        }

                        /* Memory barrier between read of packet count and call
                         * to iavf_get_tx_pending()
                         */
                        smp_rmb();
                        tx_ring->prev_pkt_ctr =
                          iavf_get_tx_pending(tx_ring, true) ? packets : -1;
                }
        }
}

#define WB_STRIDE 4

/**
 * iavf_clean_tx_irq - Reclaim resources after transmit completes
 * @vsi: the VSI we care about
 * @tx_ring: Tx ring to clean
 * @napi_budget: Used to determine if we are in netpoll
 *
 * Returns true if there's any budget left (e.g. the clean is finished)
 **/
static bool iavf_clean_tx_irq(struct iavf_vsi *vsi,
                              struct iavf_ring *tx_ring, int napi_budget)
{
        int i = tx_ring->next_to_clean;
        struct iavf_tx_buffer *tx_buf;
        struct iavf_tx_desc *tx_desc;
        unsigned int total_bytes = 0, total_packets = 0;
        unsigned int budget = IAVF_DEFAULT_IRQ_WORK;

        tx_buf = &tx_ring->tx_bi[i];
        tx_desc = IAVF_TX_DESC(tx_ring, i);
        i -= tx_ring->count;

        do {
                struct iavf_tx_desc *eop_desc = tx_buf->next_to_watch;

                /* if next_to_watch is not set then there is no work pending */
                if (!eop_desc)
                        break;

                /* prevent any other reads prior to eop_desc */
                smp_rmb();

                iavf_trace(clean_tx_irq, tx_ring, tx_desc, tx_buf);
                /* if the descriptor isn't done, no work yet to do */
                if (!(eop_desc->cmd_type_offset_bsz &
                      cpu_to_le64(IAVF_TX_DESC_DTYPE_DESC_DONE)))
                        break;

                /* clear next_to_watch to prevent false hangs */
                tx_buf->next_to_watch = NULL;

                /* update the statistics for this packet */
                total_bytes += tx_buf->bytecount;
                total_packets += tx_buf->gso_segs;

                /* free the skb */
                napi_consume_skb(tx_buf->skb, napi_budget);

                /* unmap skb header data */
                dma_unmap_single(tx_ring->dev,
                                 dma_unmap_addr(tx_buf, dma),
                                 dma_unmap_len(tx_buf, len),
                                 DMA_TO_DEVICE);

                /* clear tx_buffer data */
                tx_buf->skb = NULL;
                dma_unmap_len_set(tx_buf, len, 0);

                /* unmap remaining buffers */
                while (tx_desc != eop_desc) {
                        iavf_trace(clean_tx_irq_unmap,
                                   tx_ring, tx_desc, tx_buf);

                        tx_buf++;
                        tx_desc++;
                        i++;
                        if (unlikely(!i)) {
                                i -= tx_ring->count;
                                tx_buf = tx_ring->tx_bi;
                                tx_desc = IAVF_TX_DESC(tx_ring, 0);
                        }

                        /* unmap any remaining paged data */
                        if (dma_unmap_len(tx_buf, len)) {
                                dma_unmap_page(tx_ring->dev,
                                               dma_unmap_addr(tx_buf, dma),
                                               dma_unmap_len(tx_buf, len),
                                               DMA_TO_DEVICE);
                                dma_unmap_len_set(tx_buf, len, 0);
                        }
                }

                /* move us one more past the eop_desc for start of next pkt */
                tx_buf++;
                tx_desc++;
                i++;
                if (unlikely(!i)) {
                        i -= tx_ring->count;
                        tx_buf = tx_ring->tx_bi;
                        tx_desc = IAVF_TX_DESC(tx_ring, 0);
                }

                prefetch(tx_desc);

                /* update budget accounting */
                budget--;
        } while (likely(budget));

        i += tx_ring->count;
        tx_ring->next_to_clean = i;
        u64_stats_update_begin(&tx_ring->syncp);
        tx_ring->stats.bytes += total_bytes;
        tx_ring->stats.packets += total_packets;
        u64_stats_update_end(&tx_ring->syncp);
        tx_ring->q_vector->tx.total_bytes += total_bytes;
        tx_ring->q_vector->tx.total_packets += total_packets;

        if (tx_ring->flags & IAVF_TXR_FLAGS_WB_ON_ITR) {
                /* check to see if there are < 4 descriptors
                 * waiting to be written back, then kick the hardware to force
                 * them to be written back in case we stay in NAPI.
                 * In this mode on X722 we do not enable Interrupt.
                 */
                unsigned int j = iavf_get_tx_pending(tx_ring, false);

                if (budget &&
                    ((j / WB_STRIDE) == 0) && (j > 0) &&
                    !test_bit(__IAVF_VSI_DOWN, vsi->state) &&
                    (IAVF_DESC_UNUSED(tx_ring) != tx_ring->count))
                        tx_ring->flags |= IAVF_TXR_FLAGS_ARM_WB;
        }

        /* notify netdev of completed buffers */
        netdev_tx_completed_queue(txring_txq(tx_ring),
                                  total_packets, total_bytes);

#define TX_WAKE_THRESHOLD ((s16)(DESC_NEEDED * 2))
        if (unlikely(total_packets && netif_carrier_ok(tx_ring->netdev) &&
                     (IAVF_DESC_UNUSED(tx_ring) >= TX_WAKE_THRESHOLD))) {
                /* Make sure that anybody stopping the queue after this
                 * sees the new next_to_clean.
                 */
                smp_mb();
                if (__netif_subqueue_stopped(tx_ring->netdev,
                                             tx_ring->queue_index) &&
                   !test_bit(__IAVF_VSI_DOWN, vsi->state)) {
                        netif_wake_subqueue(tx_ring->netdev,
                                            tx_ring->queue_index);
                        ++tx_ring->tx_stats.restart_queue;
                }
        }

        return !!budget;
}

/**
 * iavf_enable_wb_on_itr - Arm hardware to do a wb, interrupts are not enabled
 * @vsi: the VSI we care about
 * @q_vector: the vector on which to enable writeback
 *
 **/
static void iavf_enable_wb_on_itr(struct iavf_vsi *vsi,
                                  struct iavf_q_vector *q_vector)
{
        u16 flags = q_vector->tx.ring[0].flags;
        u32 val;

        if (!(flags & IAVF_TXR_FLAGS_WB_ON_ITR))
                return;

        if (q_vector->arm_wb_state)
                return;

        val = IAVF_VFINT_DYN_CTLN1_WB_ON_ITR_MASK |
              IAVF_VFINT_DYN_CTLN1_ITR_INDX_MASK; /* set noitr */

        wr32(&vsi->back->hw,
             IAVF_VFINT_DYN_CTLN1(q_vector->reg_idx), val);
        q_vector->arm_wb_state = true;
}

static bool iavf_container_is_rx(struct iavf_q_vector *q_vector,
                                 struct iavf_ring_container *rc)
{
        return &q_vector->rx == rc;
}

#define IAVF_AIM_MULTIPLIER_100G        2560
#define IAVF_AIM_MULTIPLIER_50G         1280
#define IAVF_AIM_MULTIPLIER_40G         1024
#define IAVF_AIM_MULTIPLIER_20G         512
#define IAVF_AIM_MULTIPLIER_10G         256
#define IAVF_AIM_MULTIPLIER_1G          32

static unsigned int iavf_mbps_itr_multiplier(u32 speed_mbps)
{
        switch (speed_mbps) {
        case SPEED_100000:
                return IAVF_AIM_MULTIPLIER_100G;
        case SPEED_50000:
                return IAVF_AIM_MULTIPLIER_50G;
        case SPEED_40000:
                return IAVF_AIM_MULTIPLIER_40G;
        case SPEED_25000:
        case SPEED_20000:
                return IAVF_AIM_MULTIPLIER_20G;
        case SPEED_10000:
        default:
                return IAVF_AIM_MULTIPLIER_10G;
        case SPEED_1000:
        case SPEED_100:
                return IAVF_AIM_MULTIPLIER_1G;
        }
}

static unsigned int
iavf_virtchnl_itr_multiplier(enum virtchnl_link_speed speed_virtchnl)
{
        switch (speed_virtchnl) {
        case VIRTCHNL_LINK_SPEED_40GB:
                return IAVF_AIM_MULTIPLIER_40G;
        case VIRTCHNL_LINK_SPEED_25GB:
        case VIRTCHNL_LINK_SPEED_20GB:
                return IAVF_AIM_MULTIPLIER_20G;
        case VIRTCHNL_LINK_SPEED_10GB:
        default:
                return IAVF_AIM_MULTIPLIER_10G;
        case VIRTCHNL_LINK_SPEED_1GB:
        case VIRTCHNL_LINK_SPEED_100MB:
                return IAVF_AIM_MULTIPLIER_1G;
        }
}

static unsigned int iavf_itr_divisor(struct iavf_adapter *adapter)
{
        if (ADV_LINK_SUPPORT(adapter))
                return IAVF_ITR_ADAPTIVE_MIN_INC *
                        iavf_mbps_itr_multiplier(adapter->link_speed_mbps);
        else
                return IAVF_ITR_ADAPTIVE_MIN_INC *
                        iavf_virtchnl_itr_multiplier(adapter->link_speed);
}

/**
 * iavf_update_itr - update the dynamic ITR value based on statistics
 * @q_vector: structure containing interrupt and ring information
 * @rc: structure containing ring performance data
 *
 * 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.
 **/
static void iavf_update_itr(struct iavf_q_vector *q_vector,
                            struct iavf_ring_container *rc)
{
        unsigned int avg_wire_size, packets, bytes, itr;
        unsigned long next_update = jiffies;

        /* If we don't have any rings just leave ourselves set for maximum
         * possible latency so we take ourselves out of the equation.
         */
        if (!rc->ring || !ITR_IS_DYNAMIC(rc->ring->itr_setting))
                return;

        /* For Rx we want to push the delay up and default to low latency.
         * for Tx we want to pull the delay down and default to high latency.
         */
        itr = iavf_container_is_rx(q_vector, rc) ?
              IAVF_ITR_ADAPTIVE_MIN_USECS | IAVF_ITR_ADAPTIVE_LATENCY :
              IAVF_ITR_ADAPTIVE_MAX_USECS | IAVF_ITR_ADAPTIVE_LATENCY;

        /* If we didn't update within up to 1 - 2 jiffies we can assume
         * that either packets are coming in so slow there hasn't been
         * any work, or that there is so much work that NAPI is dealing
         * with interrupt moderation and we don't need to do anything.
         */
        if (time_after(next_update, rc->next_update))
                goto clear_counts;

        /* If itr_countdown is set it means we programmed an ITR within
         * the last 4 interrupt cycles. This has a side effect of us
         * potentially firing an early interrupt. In order to work around
         * this we need to throw out any data received for a few
         * interrupts following the update.
         */
        if (q_vector->itr_countdown) {
                itr = rc->target_itr;
                goto clear_counts;
        }

        packets = rc->total_packets;
        bytes = rc->total_bytes;

        if (iavf_container_is_rx(q_vector, rc)) {
                /* If Rx there are 1 to 4 packets and bytes are less than
                 * 9000 assume insufficient data to use bulk rate limiting
                 * approach unless Tx is already in bulk rate limiting. We
                 * are likely latency driven.
                 */
                if (packets && packets < 4 && bytes < 9000 &&
                    (q_vector->tx.target_itr & IAVF_ITR_ADAPTIVE_LATENCY)) {
                        itr = IAVF_ITR_ADAPTIVE_LATENCY;
                        goto adjust_by_size;
                }
        } else if (packets < 4) {
                /* If we have Tx and Rx ITR maxed and Tx ITR is running in
                 * bulk mode and we are receiving 4 or fewer packets just
                 * reset the ITR_ADAPTIVE_LATENCY bit for latency mode so
                 * that the Rx can relax.
                 */
                if (rc->target_itr == IAVF_ITR_ADAPTIVE_MAX_USECS &&
                    (q_vector->rx.target_itr & IAVF_ITR_MASK) ==
                     IAVF_ITR_ADAPTIVE_MAX_USECS)
                        goto clear_counts;
        } else if (packets > 32) {
                /* If we have processed over 32 packets in a single interrupt
                 * for Tx assume we need to switch over to "bulk" mode.
                 */
                rc->target_itr &= ~IAVF_ITR_ADAPTIVE_LATENCY;
        }

        /* We have no packets to actually measure against. This means
         * either one of the other queues on this vector is active or
         * we are a Tx queue doing TSO with too high of an interrupt rate.
         *
         * Between 4 and 56 we can assume that our current interrupt delay
         * is only slightly too low. As such we should increase it by a small
         * fixed amount.
         */
        if (packets < 56) {
                itr = rc->target_itr + IAVF_ITR_ADAPTIVE_MIN_INC;
                if ((itr & IAVF_ITR_MASK) > IAVF_ITR_ADAPTIVE_MAX_USECS) {
                        itr &= IAVF_ITR_ADAPTIVE_LATENCY;
                        itr += IAVF_ITR_ADAPTIVE_MAX_USECS;
                }
                goto clear_counts;
        }

        if (packets <= 256) {
                itr = min(q_vector->tx.current_itr, q_vector->rx.current_itr);
                itr &= IAVF_ITR_MASK;

                /* Between 56 and 112 is our "goldilocks" zone where we are
                 * working out "just right". Just report that our current
                 * ITR is good for us.
                 */
                if (packets <= 112)
                        goto clear_counts;

                /* If packet count is 128 or greater we are likely looking
                 * at a slight overrun of the delay we want. Try halving
                 * our delay to see if that will cut the number of packets
                 * in half per interrupt.
                 */
                itr /= 2;
                itr &= IAVF_ITR_MASK;
                if (itr < IAVF_ITR_ADAPTIVE_MIN_USECS)
                        itr = IAVF_ITR_ADAPTIVE_MIN_USECS;

                goto clear_counts;
        }

        /* The paths below assume we are dealing with a bulk ITR since
         * number of packets is greater than 256. We are just going to have
         * to compute a value and try to bring the count under control,
         * though for smaller packet sizes there isn't much we can do as
         * NAPI polling will likely be kicking in sooner rather than later.
         */
        itr = IAVF_ITR_ADAPTIVE_BULK;

adjust_by_size:
        /* If packet counts are 256 or greater we can assume we have a gross
         * overestimation of what the rate should be. Instead of trying to fine
         * tune it just use the formula below to try and dial in an exact value
         * give the current packet size of the frame.
         */
        avg_wire_size = bytes / packets;

        /* The following is a crude approximation of:
         *  wmem_default / (size + overhead) = desired_pkts_per_int
         *  rate / bits_per_byte / (size + ethernet overhead) = pkt_rate
         *  (desired_pkt_rate / pkt_rate) * usecs_per_sec = ITR value
         *
         * Assuming wmem_default is 212992 and overhead is 640 bytes per
         * packet, (256 skb, 64 headroom, 320 shared info), we can reduce the
         * formula down to
         *
         *  (170 * (size + 24)) / (size + 640) = ITR
         *
         * We first do some math on the packet size and then finally bitshift
         * by 8 after rounding up. We also have to account for PCIe link speed
         * difference as ITR scales based on this.
         */
        if (avg_wire_size <= 60) {
                /* Start at 250k ints/sec */
                avg_wire_size = 4096;
        } else if (avg_wire_size <= 380) {
                /* 250K ints/sec to 60K ints/sec */
                avg_wire_size *= 40;
                avg_wire_size += 1696;
        } else if (avg_wire_size <= 1084) {
                /* 60K ints/sec to 36K ints/sec */
                avg_wire_size *= 15;
                avg_wire_size += 11452;
        } else if (avg_wire_size <= 1980) {
                /* 36K ints/sec to 30K ints/sec */
                avg_wire_size *= 5;
                avg_wire_size += 22420;
        } else {
                /* plateau at a limit of 30K ints/sec */
                avg_wire_size = 32256;
        }

        /* If we are in low latency mode halve our delay which doubles the
         * rate to somewhere between 100K to 16K ints/sec
         */
        if (itr & IAVF_ITR_ADAPTIVE_LATENCY)
                avg_wire_size /= 2;

        /* Resultant value is 256 times larger than it needs to be. This
         * gives us room to adjust the value as needed to either increase
         * or decrease the value based on link speeds of 10G, 2.5G, 1G, etc.
         *
         * Use addition as we have already recorded the new latency flag
         * for the ITR value.
         */
        itr += DIV_ROUND_UP(avg_wire_size,
                            iavf_itr_divisor(q_vector->adapter)) *
                IAVF_ITR_ADAPTIVE_MIN_INC;

        if ((itr & IAVF_ITR_MASK) > IAVF_ITR_ADAPTIVE_MAX_USECS) {
                itr &= IAVF_ITR_ADAPTIVE_LATENCY;
                itr += IAVF_ITR_ADAPTIVE_MAX_USECS;
        }

clear_counts:
        /* write back value */
        rc->target_itr = itr;

        /* next update should occur within next jiffy */
        rc->next_update = next_update + 1;

        rc->total_bytes = 0;
        rc->total_packets = 0;
}

/**
 * iavf_setup_tx_descriptors - Allocate the Tx descriptors
 * @tx_ring: the tx ring to set up
 *
 * Return 0 on success, negative on error
 **/
int iavf_setup_tx_descriptors(struct iavf_ring *tx_ring)
{
        struct device *dev = tx_ring->dev;
        int bi_size;

        if (!dev)
                return -ENOMEM;

        /* warn if we are about to overwrite the pointer */
        WARN_ON(tx_ring->tx_bi);
        bi_size = sizeof(struct iavf_tx_buffer) * tx_ring->count;
        tx_ring->tx_bi = kzalloc(bi_size, GFP_KERNEL);
        if (!tx_ring->tx_bi)
                goto err;

        /* round up to nearest 4K */
        tx_ring->size = tx_ring->count * sizeof(struct iavf_tx_desc);
        tx_ring->size = ALIGN(tx_ring->size, 4096);
        tx_ring->desc = dma_alloc_coherent(dev, tx_ring->size,
                                           &tx_ring->dma, GFP_KERNEL);
        if (!tx_ring->desc) {
                dev_info(dev, "Unable to allocate memory for the Tx descriptor ring, size=%d\n",
                         tx_ring->size);
                goto err;
        }

        tx_ring->next_to_use = 0;
        tx_ring->next_to_clean = 0;
        tx_ring->prev_pkt_ctr = -1;
        return 0;

err:
        kfree(tx_ring->tx_bi);
        tx_ring->tx_bi = NULL;
        return -ENOMEM;
}

/**
 * iavf_clean_rx_ring - Free Rx buffers
 * @rx_ring: ring to be cleaned
 **/
static void iavf_clean_rx_ring(struct iavf_ring *rx_ring)
{
        /* ring already cleared, nothing to do */
        if (!rx_ring->rx_fqes)
                return;

        if (rx_ring->skb) {
                dev_kfree_skb(rx_ring->skb);
                rx_ring->skb = NULL;
        }

        /* Free all the Rx ring buffers */
        for (u32 i = rx_ring->next_to_clean; i != rx_ring->next_to_use; ) {
                const struct libeth_fqe *rx_fqes = &rx_ring->rx_fqes[i];

                libeth_rx_recycle_slow(rx_fqes->netmem);

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

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

/**
 * iavf_free_rx_resources - Free Rx resources
 * @rx_ring: ring to clean the resources from
 *
 * Free all receive software resources
 **/
void iavf_free_rx_resources(struct iavf_ring *rx_ring)
{
        struct libeth_fq fq = {
                .fqes   = rx_ring->rx_fqes,
                .pp     = rx_ring->pp,
        };

        iavf_clean_rx_ring(rx_ring);

        if (rx_ring->desc) {
                dma_free_coherent(rx_ring->pp->p.dev, rx_ring->size,
                                  rx_ring->desc, rx_ring->dma);
                rx_ring->desc = NULL;
        }

        libeth_rx_fq_destroy(&fq);
        rx_ring->rx_fqes = NULL;
        rx_ring->pp = NULL;
}

/**
 * iavf_setup_rx_descriptors - Allocate Rx descriptors
 * @rx_ring: Rx descriptor ring (for a specific queue) to setup
 *
 * Returns 0 on success, negative on failure
 **/
int iavf_setup_rx_descriptors(struct iavf_ring *rx_ring)
{
        struct libeth_fq fq = {
                .count          = rx_ring->count,
                .buf_len        = LIBIE_MAX_RX_BUF_LEN,
                .nid            = NUMA_NO_NODE,
        };
        int ret;

        ret = libeth_rx_fq_create(&fq, &rx_ring->q_vector->napi);
        if (ret)
                return ret;

        rx_ring->pp = fq.pp;
        rx_ring->rx_fqes = fq.fqes;
        rx_ring->truesize = fq.truesize;
        rx_ring->rx_buf_len = fq.buf_len;

        u64_stats_init(&rx_ring->syncp);

        /* Round up to nearest 4K */
        rx_ring->size = rx_ring->count * sizeof(struct iavf_rx_desc);
        rx_ring->size = ALIGN(rx_ring->size, 4096);
        rx_ring->desc = dma_alloc_coherent(fq.pp->p.dev, rx_ring->size,
                                           &rx_ring->dma, GFP_KERNEL);

        if (!rx_ring->desc) {
                dev_info(fq.pp->p.dev, "Unable to allocate memory for the Rx descriptor ring, size=%d\n",
                         rx_ring->size);
                goto err;
        }

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

        return 0;

err:
        libeth_rx_fq_destroy(&fq);
        rx_ring->rx_fqes = NULL;
        rx_ring->pp = NULL;

        return -ENOMEM;
}

/**
 * iavf_release_rx_desc - Store the new tail and head values
 * @rx_ring: ring to bump
 * @val: new head index
 **/
static void iavf_release_rx_desc(struct iavf_ring *rx_ring, u32 val)
{
        rx_ring->next_to_use = val;

        /* 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();
        writel(val, rx_ring->tail);
}

/**
 * iavf_receive_skb - Send a completed packet up the stack
 * @rx_ring:  rx ring in play
 * @skb: packet to send up
 * @vlan_tag: vlan tag for packet
 **/
static void iavf_receive_skb(struct iavf_ring *rx_ring,
                             struct sk_buff *skb, u16 vlan_tag)
{
        struct iavf_q_vector *q_vector = rx_ring->q_vector;

        if ((rx_ring->netdev->features & NETIF_F_HW_VLAN_CTAG_RX) &&
            (vlan_tag & VLAN_VID_MASK))
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tag);
        else if ((rx_ring->netdev->features & NETIF_F_HW_VLAN_STAG_RX) &&
                 vlan_tag & VLAN_VID_MASK)
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021AD), vlan_tag);

        napi_gro_receive(&q_vector->napi, skb);
}

/**
 * iavf_alloc_rx_buffers - Replace used receive buffers
 * @rx_ring: ring to place buffers on
 * @cleaned_count: number of buffers to replace
 *
 * Returns false if all allocations were successful, true if any fail
 **/
bool iavf_alloc_rx_buffers(struct iavf_ring *rx_ring, u16 cleaned_count)
{
        const struct libeth_fq_fp fq = {
                .pp             = rx_ring->pp,
                .fqes           = rx_ring->rx_fqes,
                .truesize       = rx_ring->truesize,
                .count          = rx_ring->count,
        };
        u16 ntu = rx_ring->next_to_use;
        struct iavf_rx_desc *rx_desc;

        /* do nothing if no valid netdev defined */
        if (!rx_ring->netdev || !cleaned_count)
                return false;

        rx_desc = IAVF_RX_DESC(rx_ring, ntu);

        do {
                dma_addr_t addr;

                addr = libeth_rx_alloc(&fq, ntu);
                if (addr == DMA_MAPPING_ERROR)
                        goto no_buffers;

                /* Refresh the desc even if buffer_addrs didn't change
                 * because each write-back erases this info.
                 */
                rx_desc->qw0 = cpu_to_le64(addr);

                rx_desc++;
                ntu++;
                if (unlikely(ntu == rx_ring->count)) {
                        rx_desc = IAVF_RX_DESC(rx_ring, 0);
                        ntu = 0;
                }

                /* clear the status bits for the next_to_use descriptor */
                rx_desc->qw1 = 0;

                cleaned_count--;
        } while (cleaned_count);

        if (rx_ring->next_to_use != ntu)
                iavf_release_rx_desc(rx_ring, ntu);

        return false;

no_buffers:
        if (rx_ring->next_to_use != ntu)
                iavf_release_rx_desc(rx_ring, ntu);

        rx_ring->rx_stats.alloc_page_failed++;

        /* make sure to come back via polling to try again after
         * allocation failure
         */
        return true;
}

/**
 * iavf_rx_csum - Indicate in skb if hw indicated a good checksum
 * @vsi: the VSI we care about
 * @skb: skb currently being received and modified
 * @decoded_pt: decoded ptype information
 * @csum_bits: decoded Rx descriptor information
 **/
static void iavf_rx_csum(const struct iavf_vsi *vsi, struct sk_buff *skb,
                         struct libeth_rx_pt decoded_pt,
                         struct libeth_rx_csum csum_bits)
{
        bool ipv4, ipv6;

        skb->ip_summed = CHECKSUM_NONE;

        /* did the hardware decode the packet and checksum? */
        if (unlikely(!csum_bits.l3l4p))
                return;

        ipv4 = libeth_rx_pt_get_ip_ver(decoded_pt) == LIBETH_RX_PT_OUTER_IPV4;
        ipv6 = libeth_rx_pt_get_ip_ver(decoded_pt) == LIBETH_RX_PT_OUTER_IPV6;

        if (unlikely(ipv4 && (csum_bits.ipe || csum_bits.eipe)))
                goto checksum_fail;

        /* likely incorrect csum if alternate IP extension headers found */
        if (unlikely(ipv6 && csum_bits.ipv6exadd))
                return;

        /* there was some L4 error, count error and punt packet to the stack */
        if (unlikely(csum_bits.l4e))
                goto checksum_fail;

        /* handle packets that were not able to be checksummed due
         * to arrival speed, in this case the stack can compute
         * the csum.
         */
        if (unlikely(csum_bits.pprs))
                return;

        skb->ip_summed = CHECKSUM_UNNECESSARY;
        return;

checksum_fail:
        vsi->back->hw_csum_rx_error++;
}

/**
 * iavf_legacy_rx_csum - Indicate in skb if hw indicated a good checksum
 * @vsi: the VSI we care about
 * @qw1: quad word 1
 * @decoded_pt: decoded packet type
 *
 * This function only operates on the VIRTCHNL_RXDID_1_32B_BASE legacy 32byte
 * descriptor writeback format.
 *
 * Return: decoded checksum bits.
 **/
static struct libeth_rx_csum
iavf_legacy_rx_csum(const struct iavf_vsi *vsi, u64 qw1,
                    const struct libeth_rx_pt decoded_pt)
{
        struct libeth_rx_csum csum_bits = {};

        if (!libeth_rx_pt_has_checksum(vsi->netdev, decoded_pt))
                return csum_bits;

        csum_bits.ipe = FIELD_GET(IAVF_RXD_LEGACY_IPE_M, qw1);
        csum_bits.eipe = FIELD_GET(IAVF_RXD_LEGACY_EIPE_M, qw1);
        csum_bits.l4e = FIELD_GET(IAVF_RXD_LEGACY_L4E_M, qw1);
        csum_bits.pprs = FIELD_GET(IAVF_RXD_LEGACY_PPRS_M, qw1);
        csum_bits.l3l4p = FIELD_GET(IAVF_RXD_LEGACY_L3L4P_M, qw1);
        csum_bits.ipv6exadd = FIELD_GET(IAVF_RXD_LEGACY_IPV6EXADD_M, qw1);

        return csum_bits;
}

/**
 * iavf_flex_rx_csum - Indicate in skb if hw indicated a good checksum
 * @vsi: the VSI we care about
 * @qw1: quad word 1
 * @decoded_pt: decoded packet type
 *
 * This function only operates on the VIRTCHNL_RXDID_2_FLEX_SQ_NIC flexible
 * descriptor writeback format.
 *
 * Return: decoded checksum bits.
 **/
static struct libeth_rx_csum
iavf_flex_rx_csum(const struct iavf_vsi *vsi, u64 qw1,
                  const struct libeth_rx_pt decoded_pt)
{
        struct libeth_rx_csum csum_bits = {};

        if (!libeth_rx_pt_has_checksum(vsi->netdev, decoded_pt))
                return csum_bits;

        csum_bits.ipe = FIELD_GET(IAVF_RXD_FLEX_XSUM_IPE_M, qw1);
        csum_bits.eipe = FIELD_GET(IAVF_RXD_FLEX_XSUM_EIPE_M, qw1);
        csum_bits.l4e = FIELD_GET(IAVF_RXD_FLEX_XSUM_L4E_M, qw1);
        csum_bits.eudpe = FIELD_GET(IAVF_RXD_FLEX_XSUM_EUDPE_M, qw1);
        csum_bits.l3l4p = FIELD_GET(IAVF_RXD_FLEX_L3L4P_M, qw1);
        csum_bits.ipv6exadd = FIELD_GET(IAVF_RXD_FLEX_IPV6EXADD_M, qw1);
        csum_bits.nat = FIELD_GET(IAVF_RXD_FLEX_NAT_M, qw1);

        return csum_bits;
}

/**
 * iavf_legacy_rx_hash - set the hash value in the skb
 * @ring: descriptor ring
 * @qw0: quad word 0
 * @qw1: quad word 1
 * @skb: skb currently being received and modified
 * @decoded_pt: decoded packet type
 *
 * This function only operates on the VIRTCHNL_RXDID_1_32B_BASE legacy 32byte
 * descriptor writeback format.
 **/
static void iavf_legacy_rx_hash(const struct iavf_ring *ring, __le64 qw0,
                                __le64 qw1, struct sk_buff *skb,
                                const struct libeth_rx_pt decoded_pt)
{
        const __le64 rss_mask = cpu_to_le64(IAVF_RXD_LEGACY_FLTSTAT_M);
        u32 hash;

        if (!libeth_rx_pt_has_hash(ring->netdev, decoded_pt))
                return;

        if ((qw1 & rss_mask) == rss_mask) {
                hash = le64_get_bits(qw0, IAVF_RXD_LEGACY_RSS_M);
                libeth_rx_pt_set_hash(skb, hash, decoded_pt);
        }
}

/**
 * iavf_flex_rx_hash - set the hash value in the skb
 * @ring: descriptor ring
 * @qw1: quad word 1
 * @skb: skb currently being received and modified
 * @decoded_pt: decoded packet type
 *
 * This function only operates on the VIRTCHNL_RXDID_2_FLEX_SQ_NIC flexible
 * descriptor writeback format.
 **/
static void iavf_flex_rx_hash(const struct iavf_ring *ring, __le64 qw1,
                              struct sk_buff *skb,
                              const struct libeth_rx_pt decoded_pt)
{
        bool rss_valid;
        u32 hash;

        if (!libeth_rx_pt_has_hash(ring->netdev, decoded_pt))
                return;

        rss_valid = le64_get_bits(qw1, IAVF_RXD_FLEX_RSS_VALID_M);
        if (rss_valid) {
                hash = le64_get_bits(qw1, IAVF_RXD_FLEX_RSS_HASH_M);
                libeth_rx_pt_set_hash(skb, hash, decoded_pt);
        }
}

/**
 * iavf_flex_rx_tstamp - Capture Rx timestamp from the descriptor
 * @rx_ring: descriptor ring
 * @qw2: quad word 2 of descriptor
 * @qw3: quad word 3 of descriptor
 * @skb: skb currently being received
 *
 * Read the Rx timestamp value from the descriptor and pass it to the stack.
 *
 * This function only operates on the VIRTCHNL_RXDID_2_FLEX_SQ_NIC flexible
 * descriptor writeback format.
 */
static void iavf_flex_rx_tstamp(const struct iavf_ring *rx_ring, __le64 qw2,
                                __le64 qw3, struct sk_buff *skb)
{
        u32 tstamp;
        u64 ns;

        /* Skip processing if timestamps aren't enabled */
        if (!(rx_ring->flags & IAVF_TXRX_FLAGS_HW_TSTAMP))
                return;

        /* Check if this Rx descriptor has a valid timestamp */
        if (!le64_get_bits(qw2, IAVF_PTP_40B_TSTAMP_VALID))
                return;

        /* the ts_low field only contains the valid bit and sub-nanosecond
         * precision, so we don't need to extract it.
         */
        tstamp = le64_get_bits(qw3, IAVF_RXD_FLEX_QW3_TSTAMP_HIGH_M);

        ns = iavf_ptp_extend_32b_timestamp(rx_ring->ptp->cached_phc_time,
                                           tstamp);

        *skb_hwtstamps(skb) = (struct skb_shared_hwtstamps) {
                .hwtstamp = ns_to_ktime(ns),
        };
}

/**
 * iavf_process_skb_fields - Populate skb header fields from Rx descriptor
 * @rx_ring: rx descriptor ring packet is being transacted on
 * @rx_desc: pointer to the EOP Rx descriptor
 * @skb: pointer to current skb being populated
 * @ptype: the packet type decoded by hardware
 * @flex: is the descriptor flex or legacy
 *
 * This function checks the ring, descriptor, and packet information in
 * order to populate the hash, checksum, VLAN, protocol, and
 * other fields within the skb.
 **/
static void iavf_process_skb_fields(const struct iavf_ring *rx_ring,
                                    const struct iavf_rx_desc *rx_desc,
                                    struct sk_buff *skb, u32 ptype,
                                    bool flex)
{
        struct libeth_rx_csum csum_bits;
        struct libeth_rx_pt decoded_pt;
        __le64 qw0 = rx_desc->qw0;
        __le64 qw1 = rx_desc->qw1;
        __le64 qw2 = rx_desc->qw2;
        __le64 qw3 = rx_desc->qw3;

        decoded_pt = libie_rx_pt_parse(ptype);

        if (flex) {
                iavf_flex_rx_hash(rx_ring, qw1, skb, decoded_pt);
                iavf_flex_rx_tstamp(rx_ring, qw2, qw3, skb);
                csum_bits = iavf_flex_rx_csum(rx_ring->vsi, le64_to_cpu(qw1),
                                              decoded_pt);
        } else {
                iavf_legacy_rx_hash(rx_ring, qw0, qw1, skb, decoded_pt);
                csum_bits = iavf_legacy_rx_csum(rx_ring->vsi, le64_to_cpu(qw1),
                                                decoded_pt);
        }
        iavf_rx_csum(rx_ring->vsi, skb, decoded_pt, csum_bits);

        skb_record_rx_queue(skb, rx_ring->queue_index);

        /* modifies the skb - consumes the enet header */
        skb->protocol = eth_type_trans(skb, rx_ring->netdev);
}

/**
 * iavf_cleanup_headers - Correct empty headers
 * @rx_ring: rx descriptor ring packet is being transacted on
 * @skb: pointer to current skb being fixed
 *
 * Also address the case where we are pulling data in on pages only
 * and as such no data is present in the skb header.
 *
 * In addition if skb is not at least 60 bytes we need to pad it so that
 * it is large enough to qualify as a valid Ethernet frame.
 *
 * Returns true if an error was encountered and skb was freed.
 **/
static bool iavf_cleanup_headers(struct iavf_ring *rx_ring, struct sk_buff *skb)
{
        /* if eth_skb_pad returns an error the skb was freed */
        if (eth_skb_pad(skb))
                return true;

        return false;
}

/**
 * iavf_add_rx_frag - Add contents of Rx buffer to sk_buff
 * @skb: sk_buff to place the data into
 * @rx_buffer: buffer containing page to add
 * @size: packet length from rx_desc
 *
 * This function will add the data contained in rx_buffer->page to the skb.
 * It will just attach the page as a frag to the skb.
 *
 * The function will then update the page offset.
 **/
static void iavf_add_rx_frag(struct sk_buff *skb,
                             const struct libeth_fqe *rx_buffer,
                             unsigned int size)
{
        u32 hr = netmem_get_pp(rx_buffer->netmem)->p.offset;

        skb_add_rx_frag_netmem(skb, skb_shinfo(skb)->nr_frags,
                               rx_buffer->netmem, rx_buffer->offset + hr,
                               size, rx_buffer->truesize);
}

/**
 * iavf_build_skb - Build skb around an existing buffer
 * @rx_buffer: Rx buffer to pull data from
 * @size: size of buffer to add to skb
 *
 * This function builds an skb around an existing Rx buffer, taking care
 * to set up the skb correctly and avoid any memcpy overhead.
 */
static struct sk_buff *iavf_build_skb(const struct libeth_fqe *rx_buffer,
                                      unsigned int size)
{
        struct page *buf_page = __netmem_to_page(rx_buffer->netmem);
        u32 hr = pp_page_to_nmdesc(buf_page)->pp->p.offset;
        struct sk_buff *skb;
        void *va;

        /* prefetch first cache line of first page */
        va = page_address(buf_page) + rx_buffer->offset;
        net_prefetch(va + hr);

        /* build an skb around the page buffer */
        skb = napi_build_skb(va, rx_buffer->truesize);
        if (unlikely(!skb))
                return NULL;

        skb_mark_for_recycle(skb);

        /* update pointers within the skb to store the data */
        skb_reserve(skb, hr);
        __skb_put(skb, size);

        return skb;
}

/**
 * iavf_is_non_eop - process handling of non-EOP buffers
 * @rx_ring: Rx ring being processed
 * @fields: Rx descriptor extracted fields
 *
 * This function updates next to clean.  If the buffer is an EOP buffer
 * this function exits returning false, otherwise it will place the
 * sk_buff in the next buffer to be chained and return true indicating
 * that this is in fact a non-EOP buffer.
 **/
static bool iavf_is_non_eop(struct iavf_ring *rx_ring,
                            struct libeth_rqe_info fields)
{
        u32 ntc = rx_ring->next_to_clean + 1;

        /* fetch, update, and store next to clean */
        ntc = (ntc < rx_ring->count) ? ntc : 0;
        rx_ring->next_to_clean = ntc;

        prefetch(IAVF_RX_DESC(rx_ring, ntc));

        /* if we are the last buffer then there is nothing else to do */
        if (likely(fields.eop))
                return false;

        rx_ring->rx_stats.non_eop_descs++;

        return true;
}

/**
 * iavf_extract_legacy_rx_fields - Extract fields from the Rx descriptor
 * @rx_ring: rx descriptor ring
 * @rx_desc: the descriptor to process
 *
 * Decode the Rx descriptor and extract relevant information including the
 * size, VLAN tag, Rx packet type, end of packet field and RXE field value.
 *
 * This function only operates on the VIRTCHNL_RXDID_1_32B_BASE legacy 32byte
 * descriptor writeback format.
 *
 * Return: fields extracted from the Rx descriptor.
 */
static struct libeth_rqe_info
iavf_extract_legacy_rx_fields(const struct iavf_ring *rx_ring,
                              const struct iavf_rx_desc *rx_desc)
{
        u64 qw0 = le64_to_cpu(rx_desc->qw0);
        u64 qw1 = le64_to_cpu(rx_desc->qw1);
        u64 qw2 = le64_to_cpu(rx_desc->qw2);
        struct libeth_rqe_info fields;
        bool l2tag1p, l2tag2p;

        fields.eop = FIELD_GET(IAVF_RXD_LEGACY_EOP_M, qw1);
        fields.len = FIELD_GET(IAVF_RXD_LEGACY_LENGTH_M, qw1);

        if (!fields.eop)
                return fields;

        fields.rxe = FIELD_GET(IAVF_RXD_LEGACY_RXE_M, qw1);
        fields.ptype = FIELD_GET(IAVF_RXD_LEGACY_PTYPE_M, qw1);
        fields.vlan = 0;

        if (rx_ring->flags & IAVF_TXRX_FLAGS_VLAN_TAG_LOC_L2TAG1) {
                l2tag1p = FIELD_GET(IAVF_RXD_LEGACY_L2TAG1P_M, qw1);
                if (l2tag1p)
                        fields.vlan = FIELD_GET(IAVF_RXD_LEGACY_L2TAG1_M, qw0);
        } else if (rx_ring->flags & IAVF_RXR_FLAGS_VLAN_TAG_LOC_L2TAG2_2) {
                l2tag2p = FIELD_GET(IAVF_RXD_LEGACY_L2TAG2P_M, qw2);
                if (l2tag2p)
                        fields.vlan = FIELD_GET(IAVF_RXD_LEGACY_L2TAG2_M, qw2);
        }

        return fields;
}

/**
 * iavf_extract_flex_rx_fields - Extract fields from the Rx descriptor
 * @rx_ring: rx descriptor ring
 * @rx_desc: the descriptor to process
 *
 * Decode the Rx descriptor and extract relevant information including the
 * size, VLAN tag, Rx packet type, end of packet field and RXE field value.
 *
 * This function only operates on the VIRTCHNL_RXDID_2_FLEX_SQ_NIC flexible
 * descriptor writeback format.
 *
 * Return: fields extracted from the Rx descriptor.
 */
static struct libeth_rqe_info
iavf_extract_flex_rx_fields(const struct iavf_ring *rx_ring,
                            const struct iavf_rx_desc *rx_desc)
{
        struct libeth_rqe_info fields = {};
        u64 qw0 = le64_to_cpu(rx_desc->qw0);
        u64 qw1 = le64_to_cpu(rx_desc->qw1);
        u64 qw2 = le64_to_cpu(rx_desc->qw2);
        bool l2tag1p, l2tag2p;

        fields.eop = FIELD_GET(IAVF_RXD_FLEX_EOP_M, qw1);
        fields.len = FIELD_GET(IAVF_RXD_FLEX_PKT_LEN_M, qw0);

        if (!fields.eop)
                return fields;

        fields.rxe = FIELD_GET(IAVF_RXD_FLEX_RXE_M, qw1);
        fields.ptype = FIELD_GET(IAVF_RXD_FLEX_PTYPE_M, qw0);
        fields.vlan = 0;

        if (rx_ring->flags & IAVF_TXRX_FLAGS_VLAN_TAG_LOC_L2TAG1) {
                l2tag1p = FIELD_GET(IAVF_RXD_FLEX_L2TAG1P_M, qw1);
                if (l2tag1p)
                        fields.vlan = FIELD_GET(IAVF_RXD_FLEX_L2TAG1_M, qw1);
        } else if (rx_ring->flags & IAVF_RXR_FLAGS_VLAN_TAG_LOC_L2TAG2_2) {
                l2tag2p = FIELD_GET(IAVF_RXD_FLEX_L2TAG2P_M, qw2);
                if (l2tag2p)
                        fields.vlan = FIELD_GET(IAVF_RXD_FLEX_L2TAG2_2_M, qw2);
        }

        return fields;
}

static struct libeth_rqe_info
iavf_extract_rx_fields(const struct iavf_ring *rx_ring,
                       const struct iavf_rx_desc *rx_desc,
                       bool flex)
{
        if (flex)
                return iavf_extract_flex_rx_fields(rx_ring, rx_desc);
        else
                return iavf_extract_legacy_rx_fields(rx_ring, rx_desc);
}

/**
 * iavf_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
 * @rx_ring: rx descriptor ring to transact packets on
 * @budget: Total limit on number of packets to process
 *
 * This function provides a "bounce buffer" approach to Rx interrupt
 * processing.  The advantage to this is that on systems that have
 * expensive overhead for IOMMU access this provides a means of avoiding
 * it by maintaining the mapping of the page to the system.
 *
 * Returns amount of work completed
 **/
static int iavf_clean_rx_irq(struct iavf_ring *rx_ring, int budget)
{
        bool flex = rx_ring->rxdid == VIRTCHNL_RXDID_2_FLEX_SQ_NIC;
        unsigned int total_rx_bytes = 0, total_rx_packets = 0;
        struct sk_buff *skb = rx_ring->skb;
        u16 cleaned_count = IAVF_DESC_UNUSED(rx_ring);
        bool failure = false;

        while (likely(total_rx_packets < (unsigned int)budget)) {
                struct libeth_rqe_info fields;
                struct libeth_fqe *rx_buffer;
                struct iavf_rx_desc *rx_desc;
                u64 qw1;

                /* return some buffers to hardware, one at a time is too slow */
                if (cleaned_count >= IAVF_RX_BUFFER_WRITE) {
                        failure = failure ||
                                  iavf_alloc_rx_buffers(rx_ring, cleaned_count);
                        cleaned_count = 0;
                }

                rx_desc = IAVF_RX_DESC(rx_ring, rx_ring->next_to_clean);

                /* This memory barrier is needed to keep us from reading
                 * any other fields out of the rx_desc until we have
                 * verified the descriptor has been written back.
                 */
                dma_rmb();

                qw1 = le64_to_cpu(rx_desc->qw1);
                /* If DD field (descriptor done) is unset then other fields are
                 * not valid
                 */
                if (!iavf_is_descriptor_done(qw1, flex))
                        break;

                fields = iavf_extract_rx_fields(rx_ring, rx_desc, flex);

                iavf_trace(clean_rx_irq, rx_ring, rx_desc, skb);

                rx_buffer = &rx_ring->rx_fqes[rx_ring->next_to_clean];
                if (!libeth_rx_sync_for_cpu(rx_buffer, fields.len))
                        goto skip_data;

                /* retrieve a buffer from the ring */
                if (skb)
                        iavf_add_rx_frag(skb, rx_buffer, fields.len);
                else
                        skb = iavf_build_skb(rx_buffer, fields.len);

                /* exit if we failed to retrieve a buffer */
                if (!skb) {
                        rx_ring->rx_stats.alloc_buff_failed++;
                        break;
                }

skip_data:
                cleaned_count++;

                if (iavf_is_non_eop(rx_ring, fields) || unlikely(!skb))
                        continue;

                /* RXE field in descriptor is an indication of the MAC errors
                 * (like CRC, alignment, oversize etc). If it is set then iavf
                 * should finish.
                 */
                if (unlikely(fields.rxe)) {
                        dev_kfree_skb_any(skb);
                        skb = NULL;
                        continue;
                }

                if (iavf_cleanup_headers(rx_ring, skb)) {
                        skb = NULL;
                        continue;
                }

                /* probably a little skewed due to removing CRC */
                total_rx_bytes += skb->len;

                /* populate checksum, VLAN, and protocol */
                iavf_process_skb_fields(rx_ring, rx_desc, skb, fields.ptype, flex);

                iavf_trace(clean_rx_irq_rx, rx_ring, rx_desc, skb);
                iavf_receive_skb(rx_ring, skb, fields.vlan);
                skb = NULL;

                /* update budget accounting */
                total_rx_packets++;
        }

        rx_ring->skb = skb;

        u64_stats_update_begin(&rx_ring->syncp);
        rx_ring->stats.packets += total_rx_packets;
        rx_ring->stats.bytes += total_rx_bytes;
        u64_stats_update_end(&rx_ring->syncp);
        rx_ring->q_vector->rx.total_packets += total_rx_packets;
        rx_ring->q_vector->rx.total_bytes += total_rx_bytes;

        /* guarantee a trip back through this routine if there was a failure */
        return failure ? budget : (int)total_rx_packets;
}

static inline u32 iavf_buildreg_itr(const int type, u16 itr)
{
        u32 val;

        /* We don't bother with setting the CLEARPBA bit as the data sheet
         * points out doing so is "meaningless since it was already
         * auto-cleared". The auto-clearing happens when the interrupt is
         * asserted.
         *
         * Hardware errata 28 for also indicates that writing to a
         * xxINT_DYN_CTLx CSR with INTENA_MSK (bit 31) set to 0 will clear
         * an event in the PBA anyway so we need to rely on the automask
         * to hold pending events for us until the interrupt is re-enabled
         *
         * The itr value is reported in microseconds, and the register
         * value is recorded in 2 microsecond units. For this reason we
         * only need to shift by the interval shift - 1 instead of the
         * full value.
         */
        itr &= IAVF_ITR_MASK;

        val = IAVF_VFINT_DYN_CTLN1_INTENA_MASK |
              (type << IAVF_VFINT_DYN_CTLN1_ITR_INDX_SHIFT) |
              (itr << (IAVF_VFINT_DYN_CTLN1_INTERVAL_SHIFT - 1));

        return val;
}

/* a small macro to shorten up some long lines */
#define INTREG IAVF_VFINT_DYN_CTLN1

/* The act of updating the ITR will cause it to immediately trigger. In order
 * to prevent this from throwing off adaptive update statistics we defer the
 * update so that it can only happen so often. So after either Tx or Rx are
 * updated we make the adaptive scheme wait until either the ITR completely
 * expires via the next_update expiration or we have been through at least
 * 3 interrupts.
 */
#define ITR_COUNTDOWN_START 3

/**
 * iavf_update_enable_itr - Update itr and re-enable MSIX interrupt
 * @vsi: the VSI we care about
 * @q_vector: q_vector for which itr is being updated and interrupt enabled
 *
 **/
static void iavf_update_enable_itr(struct iavf_vsi *vsi,
                                   struct iavf_q_vector *q_vector)
{
        struct iavf_hw *hw = &vsi->back->hw;
        u32 intval;

        /* These will do nothing if dynamic updates are not enabled */
        iavf_update_itr(q_vector, &q_vector->tx);
        iavf_update_itr(q_vector, &q_vector->rx);

        /* This block of logic allows us to get away with only updating
         * one ITR value with each interrupt. The idea is to perform a
         * pseudo-lazy update with the following criteria.
         *
         * 1. Rx is given higher priority than Tx if both are in same state
         * 2. If we must reduce an ITR that is given highest priority.
         * 3. We then give priority to increasing ITR based on amount.
         */
        if (q_vector->rx.target_itr < q_vector->rx.current_itr) {
                /* Rx ITR needs to be reduced, this is highest priority */
                intval = iavf_buildreg_itr(IAVF_RX_ITR,
                                           q_vector->rx.target_itr);
                q_vector->rx.current_itr = q_vector->rx.target_itr;
                q_vector->itr_countdown = ITR_COUNTDOWN_START;
        } else if ((q_vector->tx.target_itr < q_vector->tx.current_itr) ||
                   ((q_vector->rx.target_itr - q_vector->rx.current_itr) <
                    (q_vector->tx.target_itr - q_vector->tx.current_itr))) {
                /* Tx ITR needs to be reduced, this is second priority
                 * Tx ITR needs to be increased more than Rx, fourth priority
                 */
                intval = iavf_buildreg_itr(IAVF_TX_ITR,
                                           q_vector->tx.target_itr);
                q_vector->tx.current_itr = q_vector->tx.target_itr;
                q_vector->itr_countdown = ITR_COUNTDOWN_START;
        } else if (q_vector->rx.current_itr != q_vector->rx.target_itr) {
                /* Rx ITR needs to be increased, third priority */
                intval = iavf_buildreg_itr(IAVF_RX_ITR,
                                           q_vector->rx.target_itr);
                q_vector->rx.current_itr = q_vector->rx.target_itr;
                q_vector->itr_countdown = ITR_COUNTDOWN_START;
        } else {
                /* No ITR update, lowest priority */
                intval = iavf_buildreg_itr(IAVF_ITR_NONE, 0);
                if (q_vector->itr_countdown)
                        q_vector->itr_countdown--;
        }

        if (!test_bit(__IAVF_VSI_DOWN, vsi->state))
                wr32(hw, INTREG(q_vector->reg_idx), intval);
}

/**
 * iavf_napi_poll - NAPI polling Rx/Tx cleanup routine
 * @napi: napi struct with our devices info in it
 * @budget: amount of work driver is allowed to do this pass, in packets
 *
 * This function will clean all queues associated with a q_vector.
 *
 * Returns the amount of work done
 **/
int iavf_napi_poll(struct napi_struct *napi, int budget)
{
        struct iavf_q_vector *q_vector =
                               container_of(napi, struct iavf_q_vector, napi);
        struct iavf_vsi *vsi = q_vector->vsi;
        struct iavf_ring *ring;
        bool clean_complete = true;
        bool arm_wb = false;
        int budget_per_ring;
        int work_done = 0;

        if (test_bit(__IAVF_VSI_DOWN, vsi->state)) {
                napi_complete(napi);
                return 0;
        }

        /* Since the actual Tx work is minimal, we can give the Tx a larger
         * budget and be more aggressive about cleaning up the Tx descriptors.
         */
        iavf_for_each_ring(ring, q_vector->tx) {
                if (!iavf_clean_tx_irq(vsi, ring, budget)) {
                        clean_complete = false;
                        continue;
                }
                arm_wb |= !!(ring->flags & IAVF_TXR_FLAGS_ARM_WB);
                ring->flags &= ~IAVF_TXR_FLAGS_ARM_WB;
        }

        /* Handle case where we are called by netpoll with a budget of 0 */
        if (budget <= 0)
                goto tx_only;

        /* We attempt to distribute budget to each Rx queue fairly, but don't
         * allow the budget to go below 1 because that would exit polling early.
         */
        budget_per_ring = max(budget/q_vector->num_ringpairs, 1);

        iavf_for_each_ring(ring, q_vector->rx) {
                int cleaned = iavf_clean_rx_irq(ring, budget_per_ring);

                work_done += cleaned;
                /* if we clean as many as budgeted, we must not be done */
                if (cleaned >= budget_per_ring)
                        clean_complete = false;
        }

        /* If work not completed, return budget and polling will return */
        if (!clean_complete) {
                int cpu_id = smp_processor_id();

                /* It is possible that the interrupt affinity has changed but,
                 * if the cpu is pegged at 100%, polling will never exit while
                 * traffic continues and the interrupt will be stuck on this
                 * cpu.  We check to make sure affinity is correct before we
                 * continue to poll, otherwise we must stop polling so the
                 * interrupt can move to the correct cpu.
                 */
                if (!cpumask_test_cpu(cpu_id,
                                      &q_vector->napi.config->affinity_mask)) {
                        /* Tell napi that we are done polling */
                        napi_complete_done(napi, work_done);

                        /* Force an interrupt */
                        iavf_force_wb(vsi, q_vector);

                        /* Return budget-1 so that polling stops */
                        return budget - 1;
                }
tx_only:
                if (arm_wb) {
                        q_vector->tx.ring[0].tx_stats.tx_force_wb++;
                        iavf_enable_wb_on_itr(vsi, q_vector);
                }
                return budget;
        }

        if (vsi->back->flags & IAVF_TXR_FLAGS_WB_ON_ITR)
                q_vector->arm_wb_state = false;

        /* Exit the polling mode, but don't re-enable interrupts if stack might
         * poll us due to busy-polling
         */
        if (likely(napi_complete_done(napi, work_done)))
                iavf_update_enable_itr(vsi, q_vector);

        return min_t(int, work_done, budget - 1);
}

/**
 * iavf_tx_prepare_vlan_flags - prepare generic TX VLAN tagging flags for HW
 * @skb:     send buffer
 * @tx_ring: ring to send buffer on
 * @flags:   the tx flags to be set
 *
 * Checks the skb and set up correspondingly several generic transmit flags
 * related to VLAN tagging for the HW, such as VLAN, DCB, etc.
 *
 * Returns error code indicate the frame should be dropped upon error and the
 * otherwise  returns 0 to indicate the flags has been set properly.
 **/
static void iavf_tx_prepare_vlan_flags(struct sk_buff *skb,
                                       struct iavf_ring *tx_ring, u32 *flags)
{
        u32  tx_flags = 0;


        /* stack will only request hardware VLAN insertion offload for protocols
         * that the driver supports and has enabled
         */
        if (!skb_vlan_tag_present(skb))
                return;

        tx_flags |= skb_vlan_tag_get(skb) << IAVF_TX_FLAGS_VLAN_SHIFT;
        if (tx_ring->flags & IAVF_TXR_FLAGS_VLAN_TAG_LOC_L2TAG2) {
                tx_flags |= IAVF_TX_FLAGS_HW_OUTER_SINGLE_VLAN;
        } else if (tx_ring->flags & IAVF_TXRX_FLAGS_VLAN_TAG_LOC_L2TAG1) {
                tx_flags |= IAVF_TX_FLAGS_HW_VLAN;
        } else {
                dev_dbg(tx_ring->dev, "Unsupported Tx VLAN tag location requested\n");
                return;
        }

        *flags = tx_flags;
}

/**
 * iavf_tso - set up the tso context descriptor
 * @first:    pointer to first Tx buffer for xmit
 * @hdr_len:  ptr to the size of the packet header
 * @cd_type_cmd_tso_mss: Quad Word 1
 *
 * Returns 0 if no TSO can happen, 1 if tso is going, or error
 **/
static int iavf_tso(struct iavf_tx_buffer *first, u8 *hdr_len,
                    u64 *cd_type_cmd_tso_mss)
{
        struct sk_buff *skb = first->skb;
        u64 cd_cmd, cd_tso_len, cd_mss;
        union {
                struct iphdr *v4;
                struct ipv6hdr *v6;
                unsigned char *hdr;
        } ip;
        union {
                struct tcphdr *tcp;
                struct udphdr *udp;
                unsigned char *hdr;
        } l4;
        u32 paylen, l4_offset;
        u16 gso_segs, gso_size;
        int err;

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                return 0;

        if (!skb_is_gso(skb))
                return 0;

        err = skb_cow_head(skb, 0);
        if (err < 0)
                return err;

        ip.hdr = skb_network_header(skb);
        l4.hdr = skb_transport_header(skb);

        /* initialize outer IP header fields */
        if (ip.v4->version == 4) {
                ip.v4->tot_len = 0;
                ip.v4->check = 0;
        } else {
                ip.v6->payload_len = 0;
        }

        if (skb_shinfo(skb)->gso_type & (SKB_GSO_GRE |
                                         SKB_GSO_GRE_CSUM |
                                         SKB_GSO_IPXIP4 |
                                         SKB_GSO_IPXIP6 |
                                         SKB_GSO_UDP_TUNNEL |
                                         SKB_GSO_UDP_TUNNEL_CSUM)) {
                if (!(skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) &&
                    (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM)) {
                        l4.udp->len = 0;

                        /* determine offset of outer transport header */
                        l4_offset = l4.hdr - skb->data;

                        /* remove payload length from outer checksum */
                        paylen = skb->len - l4_offset;
                        csum_replace_by_diff(&l4.udp->check,
                                             (__force __wsum)htonl(paylen));
                }

                /* reset pointers to inner headers */
                ip.hdr = skb_inner_network_header(skb);
                l4.hdr = skb_inner_transport_header(skb);

                /* initialize inner IP header fields */
                if (ip.v4->version == 4) {
                        ip.v4->tot_len = 0;
                        ip.v4->check = 0;
                } else {
                        ip.v6->payload_len = 0;
                }
        }

        /* determine offset of inner transport header */
        l4_offset = l4.hdr - skb->data;
        /* remove payload length from inner checksum */
        paylen = skb->len - l4_offset;

        if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) {
                csum_replace_by_diff(&l4.udp->check,
                                     (__force __wsum)htonl(paylen));
                /* compute length of UDP segmentation header */
                *hdr_len = (u8)sizeof(l4.udp) + l4_offset;
        } else {
                csum_replace_by_diff(&l4.tcp->check,
                                     (__force __wsum)htonl(paylen));
                /* compute length of TCP segmentation header */
                *hdr_len = (u8)((l4.tcp->doff * 4) + l4_offset);
        }

        /* pull values out of skb_shinfo */
        gso_size = skb_shinfo(skb)->gso_size;
        gso_segs = skb_shinfo(skb)->gso_segs;

        /* update GSO size and bytecount with header size */
        first->gso_segs = gso_segs;
        first->bytecount += (first->gso_segs - 1) * *hdr_len;

        /* find the field values */
        cd_cmd = IAVF_TX_CTX_DESC_TSO;
        cd_tso_len = skb->len - *hdr_len;
        cd_mss = gso_size;
        *cd_type_cmd_tso_mss |= (cd_cmd << IAVF_TXD_CTX_QW1_CMD_SHIFT) |
                                (cd_tso_len << IAVF_TXD_CTX_QW1_TSO_LEN_SHIFT) |
                                (cd_mss << IAVF_TXD_CTX_QW1_MSS_SHIFT);
        return 1;
}

/**
 * iavf_tx_enable_csum - Enable Tx checksum offloads
 * @skb: send buffer
 * @tx_flags: pointer to Tx flags currently set
 * @td_cmd: Tx descriptor command bits to set
 * @td_offset: Tx descriptor header offsets to set
 * @tx_ring: Tx descriptor ring
 * @cd_tunneling: ptr to context desc bits
 **/
static int iavf_tx_enable_csum(struct sk_buff *skb, u32 *tx_flags,
                               u32 *td_cmd, u32 *td_offset,
                               struct iavf_ring *tx_ring,
                               u32 *cd_tunneling)
{
        union {
                struct iphdr *v4;
                struct ipv6hdr *v6;
                unsigned char *hdr;
        } ip;
        union {
                struct tcphdr *tcp;
                struct udphdr *udp;
                unsigned char *hdr;
        } l4;
        unsigned char *exthdr;
        u32 offset, cmd = 0;
        __be16 frag_off;
        u8 l4_proto = 0;

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                return 0;

        ip.hdr = skb_network_header(skb);
        l4.hdr = skb_transport_header(skb);

        /* compute outer L2 header size */
        offset = ((ip.hdr - skb->data) / 2) << IAVF_TX_DESC_LENGTH_MACLEN_SHIFT;

        if (skb->encapsulation) {
                u32 tunnel = 0;
                /* define outer network header type */
                if (*tx_flags & IAVF_TX_FLAGS_IPV4) {
                        tunnel |= (*tx_flags & IAVF_TX_FLAGS_TSO) ?
                                  IAVF_TX_CTX_EXT_IP_IPV4 :
                                  IAVF_TX_CTX_EXT_IP_IPV4_NO_CSUM;

                        l4_proto = ip.v4->protocol;
                } else if (*tx_flags & IAVF_TX_FLAGS_IPV6) {
                        tunnel |= IAVF_TX_CTX_EXT_IP_IPV6;

                        exthdr = ip.hdr + sizeof(*ip.v6);
                        l4_proto = ip.v6->nexthdr;
                        if (l4.hdr != exthdr)
                                ipv6_skip_exthdr(skb, exthdr - skb->data,
                                                 &l4_proto, &frag_off);
                }

                /* define outer transport */
                switch (l4_proto) {
                case IPPROTO_UDP:
                        tunnel |= IAVF_TXD_CTX_UDP_TUNNELING;
                        *tx_flags |= IAVF_TX_FLAGS_VXLAN_TUNNEL;
                        break;
                case IPPROTO_GRE:
                        tunnel |= IAVF_TXD_CTX_GRE_TUNNELING;
                        *tx_flags |= IAVF_TX_FLAGS_VXLAN_TUNNEL;
                        break;
                case IPPROTO_IPIP:
                case IPPROTO_IPV6:
                        *tx_flags |= IAVF_TX_FLAGS_VXLAN_TUNNEL;
                        l4.hdr = skb_inner_network_header(skb);
                        break;
                default:
                        if (*tx_flags & IAVF_TX_FLAGS_TSO)
                                return -1;

                        skb_checksum_help(skb);
                        return 0;
                }

                /* compute outer L3 header size */
                tunnel |= ((l4.hdr - ip.hdr) / 4) <<
                          IAVF_TXD_CTX_QW0_EXT_IPLEN_SHIFT;

                /* switch IP header pointer from outer to inner header */
                ip.hdr = skb_inner_network_header(skb);

                /* compute tunnel header size */
                tunnel |= ((ip.hdr - l4.hdr) / 2) <<
                          IAVF_TXD_CTX_QW0_NATLEN_SHIFT;

                /* indicate if we need to offload outer UDP header */
                if ((*tx_flags & IAVF_TX_FLAGS_TSO) &&
                    !(skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) &&
                    (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM))
                        tunnel |= IAVF_TXD_CTX_QW0_L4T_CS_MASK;

                /* record tunnel offload values */
                *cd_tunneling |= tunnel;

                /* switch L4 header pointer from outer to inner */
                l4.hdr = skb_inner_transport_header(skb);
                l4_proto = 0;

                /* reset type as we transition from outer to inner headers */
                *tx_flags &= ~(IAVF_TX_FLAGS_IPV4 | IAVF_TX_FLAGS_IPV6);
                if (ip.v4->version == 4)
                        *tx_flags |= IAVF_TX_FLAGS_IPV4;
                if (ip.v6->version == 6)
                        *tx_flags |= IAVF_TX_FLAGS_IPV6;
        }

        /* Enable IP checksum offloads */
        if (*tx_flags & IAVF_TX_FLAGS_IPV4) {
                l4_proto = ip.v4->protocol;
                /* the stack computes the IP header already, the only time we
                 * need the hardware to recompute it is in the case of TSO.
                 */
                cmd |= (*tx_flags & IAVF_TX_FLAGS_TSO) ?
                       IAVF_TX_DESC_CMD_IIPT_IPV4_CSUM :
                       IAVF_TX_DESC_CMD_IIPT_IPV4;
        } else if (*tx_flags & IAVF_TX_FLAGS_IPV6) {
                cmd |= IAVF_TX_DESC_CMD_IIPT_IPV6;

                exthdr = ip.hdr + sizeof(*ip.v6);
                l4_proto = ip.v6->nexthdr;
                if (l4.hdr != exthdr)
                        ipv6_skip_exthdr(skb, exthdr - skb->data,
                                         &l4_proto, &frag_off);
        }

        /* compute inner L3 header size */
        offset |= ((l4.hdr - ip.hdr) / 4) << IAVF_TX_DESC_LENGTH_IPLEN_SHIFT;

        /* Enable L4 checksum offloads */
        switch (l4_proto) {
        case IPPROTO_TCP:
                /* enable checksum offloads */
                cmd |= IAVF_TX_DESC_CMD_L4T_EOFT_TCP;
                offset |= l4.tcp->doff << IAVF_TX_DESC_LENGTH_L4_FC_LEN_SHIFT;
                break;
        case IPPROTO_SCTP:
                /* enable SCTP checksum offload */
                cmd |= IAVF_TX_DESC_CMD_L4T_EOFT_SCTP;
                offset |= (sizeof(struct sctphdr) >> 2) <<
                          IAVF_TX_DESC_LENGTH_L4_FC_LEN_SHIFT;
                break;
        case IPPROTO_UDP:
                /* enable UDP checksum offload */
                cmd |= IAVF_TX_DESC_CMD_L4T_EOFT_UDP;
                offset |= (sizeof(struct udphdr) >> 2) <<
                          IAVF_TX_DESC_LENGTH_L4_FC_LEN_SHIFT;
                break;
        default:
                if (*tx_flags & IAVF_TX_FLAGS_TSO)
                        return -1;
                skb_checksum_help(skb);
                return 0;
        }

        *td_cmd |= cmd;
        *td_offset |= offset;

        return 1;
}

/**
 * iavf_create_tx_ctx - Build the Tx context descriptor
 * @tx_ring:  ring to create the descriptor on
 * @cd_type_cmd_tso_mss: Quad Word 1
 * @cd_tunneling: Quad Word 0 - bits 0-31
 * @cd_l2tag2: Quad Word 0 - bits 32-63
 **/
static void iavf_create_tx_ctx(struct iavf_ring *tx_ring,
                               const u64 cd_type_cmd_tso_mss,
                               const u32 cd_tunneling, const u32 cd_l2tag2)
{
        struct iavf_tx_context_desc *context_desc;
        int i = tx_ring->next_to_use;

        if ((cd_type_cmd_tso_mss == IAVF_TX_DESC_DTYPE_CONTEXT) &&
            !cd_tunneling && !cd_l2tag2)
                return;

        /* grab the next descriptor */
        context_desc = IAVF_TX_CTXTDESC(tx_ring, i);

        i++;
        tx_ring->next_to_use = (i < tx_ring->count) ? i : 0;

        /* cpu_to_le32 and assign to struct fields */
        context_desc->tunneling_params = cpu_to_le32(cd_tunneling);
        context_desc->l2tag2 = cpu_to_le16(cd_l2tag2);
        context_desc->rsvd = cpu_to_le16(0);
        context_desc->type_cmd_tso_mss = cpu_to_le64(cd_type_cmd_tso_mss);
}

/**
 * __iavf_chk_linearize - Check if there are more than 8 buffers per packet
 * @skb:      send buffer
 *
 * Note: Our HW can't DMA more than 8 buffers to build a packet on the wire
 * and so we need to figure out the cases where we need to linearize the skb.
 *
 * For TSO we need to count the TSO header and segment payload separately.
 * As such we need to check cases where we have 7 fragments or more as we
 * can potentially require 9 DMA transactions, 1 for the TSO header, 1 for
 * the segment payload in the first descriptor, and another 7 for the
 * fragments.
 **/
bool __iavf_chk_linearize(struct sk_buff *skb)
{
        const skb_frag_t *frag, *stale;
        int nr_frags, sum;

        /* no need to check if number of frags is less than 7 */
        nr_frags = skb_shinfo(skb)->nr_frags;
        if (nr_frags < (IAVF_MAX_BUFFER_TXD - 1))
                return false;

        /* We need to walk through the list and validate that each group
         * of 6 fragments totals at least gso_size.
         */
        nr_frags -= IAVF_MAX_BUFFER_TXD - 2;
        frag = &skb_shinfo(skb)->frags[0];

        /* Initialize size to the negative value of gso_size minus 1.  We
         * use this as the worst case scenerio in which the frag ahead
         * of us only provides one byte which is why we are limited to 6
         * descriptors for a single transmit as the header and previous
         * fragment are already consuming 2 descriptors.
         */
        sum = 1 - skb_shinfo(skb)->gso_size;

        /* Add size of frags 0 through 4 to create our initial sum */
        sum += skb_frag_size(frag++);
        sum += skb_frag_size(frag++);
        sum += skb_frag_size(frag++);
        sum += skb_frag_size(frag++);
        sum += skb_frag_size(frag++);

        /* Walk through fragments adding latest fragment, testing it, and
         * then removing stale fragments from the sum.
         */
        for (stale = &skb_shinfo(skb)->frags[0];; stale++) {
                int stale_size = skb_frag_size(stale);

                sum += skb_frag_size(frag++);

                /* The stale fragment may present us with a smaller
                 * descriptor than the actual fragment size. To account
                 * for that we need to remove all the data on the front and
                 * figure out what the remainder would be in the last
                 * descriptor associated with the fragment.
                 */
                if (stale_size > IAVF_MAX_DATA_PER_TXD) {
                        int align_pad = -(skb_frag_off(stale)) &
                                        (IAVF_MAX_READ_REQ_SIZE - 1);

                        sum -= align_pad;
                        stale_size -= align_pad;

                        do {
                                sum -= IAVF_MAX_DATA_PER_TXD_ALIGNED;
                                stale_size -= IAVF_MAX_DATA_PER_TXD_ALIGNED;
                        } while (stale_size > IAVF_MAX_DATA_PER_TXD);
                }

                /* if sum is negative we failed to make sufficient progress */
                if (sum < 0)
                        return true;

                if (!nr_frags--)
                        break;

                sum -= stale_size;
        }

        return false;
}

/**
 * __iavf_maybe_stop_tx - 2nd level check for tx stop conditions
 * @tx_ring: the ring to be checked
 * @size:    the size buffer we want to assure is available
 *
 * Returns -EBUSY if a stop is needed, else 0
 **/
int __iavf_maybe_stop_tx(struct iavf_ring *tx_ring, int size)
{
        netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);
        /* Memory barrier before checking head and tail */
        smp_mb();

        /* Check again in a case another CPU has just made room available. */
        if (likely(IAVF_DESC_UNUSED(tx_ring) < size))
                return -EBUSY;

        /* A reprieve! - use start_queue because it doesn't call schedule */
        netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index);
        ++tx_ring->tx_stats.restart_queue;
        return 0;
}

/**
 * iavf_tx_map - Build the Tx descriptor
 * @tx_ring:  ring to send buffer on
 * @skb:      send buffer
 * @first:    first buffer info buffer to use
 * @tx_flags: collected send information
 * @hdr_len:  size of the packet header
 * @td_cmd:   the command field in the descriptor
 * @td_offset: offset for checksum or crc
 **/
static void iavf_tx_map(struct iavf_ring *tx_ring, struct sk_buff *skb,
                        struct iavf_tx_buffer *first, u32 tx_flags,
                        const u8 hdr_len, u32 td_cmd, u32 td_offset)
{
        unsigned int data_len = skb->data_len;
        unsigned int size = skb_headlen(skb);
        skb_frag_t *frag;
        struct iavf_tx_buffer *tx_bi;
        struct iavf_tx_desc *tx_desc;
        u16 i = tx_ring->next_to_use;
        u32 td_tag = 0;
        dma_addr_t dma;

        if (tx_flags & IAVF_TX_FLAGS_HW_VLAN) {
                td_cmd |= IAVF_TX_DESC_CMD_IL2TAG1;
                td_tag = FIELD_GET(IAVF_TX_FLAGS_VLAN_MASK, tx_flags);
        }

        first->tx_flags = tx_flags;

        dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);

        tx_desc = IAVF_TX_DESC(tx_ring, i);
        tx_bi = first;

        for (frag = &skb_shinfo(skb)->frags[0];; frag++) {
                unsigned int max_data = IAVF_MAX_DATA_PER_TXD_ALIGNED;

                if (dma_mapping_error(tx_ring->dev, dma))
                        goto dma_error;

                /* record length, and DMA address */
                dma_unmap_len_set(tx_bi, len, size);
                dma_unmap_addr_set(tx_bi, dma, dma);

                /* align size to end of page */
                max_data += -dma & (IAVF_MAX_READ_REQ_SIZE - 1);
                tx_desc->buffer_addr = cpu_to_le64(dma);

                while (unlikely(size > IAVF_MAX_DATA_PER_TXD)) {
                        tx_desc->cmd_type_offset_bsz =
                                build_ctob(td_cmd, td_offset,
                                           max_data, td_tag);

                        tx_desc++;
                        i++;

                        if (i == tx_ring->count) {
                                tx_desc = IAVF_TX_DESC(tx_ring, 0);
                                i = 0;
                        }

                        dma += max_data;
                        size -= max_data;

                        max_data = IAVF_MAX_DATA_PER_TXD_ALIGNED;
                        tx_desc->buffer_addr = cpu_to_le64(dma);
                }

                if (likely(!data_len))
                        break;

                tx_desc->cmd_type_offset_bsz = build_ctob(td_cmd, td_offset,
                                                          size, td_tag);

                tx_desc++;
                i++;

                if (i == tx_ring->count) {
                        tx_desc = IAVF_TX_DESC(tx_ring, 0);
                        i = 0;
                }

                size = skb_frag_size(frag);
                data_len -= size;

                dma = skb_frag_dma_map(tx_ring->dev, frag, 0, size,
                                       DMA_TO_DEVICE);

                tx_bi = &tx_ring->tx_bi[i];
        }

        netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);

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

        tx_ring->next_to_use = i;

        iavf_maybe_stop_tx(tx_ring, DESC_NEEDED);

        /* write last descriptor with RS and EOP bits */
        td_cmd |= IAVF_TXD_CMD;
        tx_desc->cmd_type_offset_bsz =
                        build_ctob(td_cmd, td_offset, size, td_tag);

        skb_tx_timestamp(skb);

        /* Force memory writes to complete before letting h/w know there
         * are new descriptors to fetch.
         *
         * We also use this memory barrier to make certain all of the
         * status bits have been updated before next_to_watch is written.
         */
        wmb();

        /* set next_to_watch value indicating a packet is present */
        first->next_to_watch = tx_desc;

        /* notify HW of packet */
        if (netif_xmit_stopped(txring_txq(tx_ring)) || !netdev_xmit_more()) {
                writel(i, tx_ring->tail);
        }

        return;

dma_error:
        dev_info(tx_ring->dev, "TX DMA map failed\n");

        /* clear dma mappings for failed tx_bi map */
        for (;;) {
                tx_bi = &tx_ring->tx_bi[i];
                iavf_unmap_and_free_tx_resource(tx_ring, tx_bi);
                if (tx_bi == first)
                        break;
                if (i == 0)
                        i = tx_ring->count;
                i--;
        }

        tx_ring->next_to_use = i;
}

/**
 * iavf_xmit_frame_ring - Sends buffer on Tx ring
 * @skb:     send buffer
 * @tx_ring: ring to send buffer on
 *
 * Returns NETDEV_TX_OK if sent, else an error code
 **/
static netdev_tx_t iavf_xmit_frame_ring(struct sk_buff *skb,
                                        struct iavf_ring *tx_ring)
{
        u64 cd_type_cmd_tso_mss = IAVF_TX_DESC_DTYPE_CONTEXT;
        u32 cd_tunneling = 0, cd_l2tag2 = 0;
        struct iavf_tx_buffer *first;
        u32 td_offset = 0;
        u32 tx_flags = 0;
        __be16 protocol;
        u32 td_cmd = 0;
        u8 hdr_len = 0;
        int tso, count;

        /* prefetch the data, we'll need it later */
        prefetch(skb->data);

        iavf_trace(xmit_frame_ring, skb, tx_ring);

        count = iavf_xmit_descriptor_count(skb);
        if (iavf_chk_linearize(skb, count)) {
                if (__skb_linearize(skb)) {
                        dev_kfree_skb_any(skb);
                        return NETDEV_TX_OK;
                }
                count = iavf_txd_use_count(skb->len);
                tx_ring->tx_stats.tx_linearize++;
        }

        /* need: 1 descriptor per page * PAGE_SIZE/IAVF_MAX_DATA_PER_TXD,
         *       + 1 desc for skb_head_len/IAVF_MAX_DATA_PER_TXD,
         *       + 4 desc gap to avoid the cache line where head is,
         *       + 1 desc for context descriptor,
         * otherwise try next time
         */
        if (iavf_maybe_stop_tx(tx_ring, count + 4 + 1)) {
                tx_ring->tx_stats.tx_busy++;
                return NETDEV_TX_BUSY;
        }

        /* record the location of the first descriptor for this packet */
        first = &tx_ring->tx_bi[tx_ring->next_to_use];
        first->skb = skb;
        first->bytecount = skb->len;
        first->gso_segs = 1;

        /* prepare the xmit flags */
        iavf_tx_prepare_vlan_flags(skb, tx_ring, &tx_flags);
        if (tx_flags & IAVF_TX_FLAGS_HW_OUTER_SINGLE_VLAN) {
                cd_type_cmd_tso_mss |= IAVF_TX_CTX_DESC_IL2TAG2 <<
                        IAVF_TXD_CTX_QW1_CMD_SHIFT;
                cd_l2tag2 = FIELD_GET(IAVF_TX_FLAGS_VLAN_MASK, tx_flags);
        }

        /* obtain protocol of skb */
        protocol = vlan_get_protocol(skb);

        /* setup IPv4/IPv6 offloads */
        if (protocol == htons(ETH_P_IP))
                tx_flags |= IAVF_TX_FLAGS_IPV4;
        else if (protocol == htons(ETH_P_IPV6))
                tx_flags |= IAVF_TX_FLAGS_IPV6;

        tso = iavf_tso(first, &hdr_len, &cd_type_cmd_tso_mss);

        if (tso < 0)
                goto out_drop;
        else if (tso)
                tx_flags |= IAVF_TX_FLAGS_TSO;

        /* Always offload the checksum, since it's in the data descriptor */
        tso = iavf_tx_enable_csum(skb, &tx_flags, &td_cmd, &td_offset,
                                  tx_ring, &cd_tunneling);
        if (tso < 0)
                goto out_drop;

        /* always enable CRC insertion offload */
        td_cmd |= IAVF_TX_DESC_CMD_ICRC;

        iavf_create_tx_ctx(tx_ring, cd_type_cmd_tso_mss,
                           cd_tunneling, cd_l2tag2);

        iavf_tx_map(tx_ring, skb, first, tx_flags, hdr_len,
                    td_cmd, td_offset);

        return NETDEV_TX_OK;

out_drop:
        iavf_trace(xmit_frame_ring_drop, first->skb, tx_ring);
        dev_kfree_skb_any(first->skb);
        first->skb = NULL;
        return NETDEV_TX_OK;
}

/**
 * iavf_xmit_frame - Selects the correct VSI and Tx queue to send buffer
 * @skb:    send buffer
 * @netdev: network interface device structure
 *
 * Returns NETDEV_TX_OK if sent, else an error code
 **/
netdev_tx_t iavf_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
{
        struct iavf_adapter *adapter = netdev_priv(netdev);
        struct iavf_ring *tx_ring = &adapter->tx_rings[skb->queue_mapping];

        /* hardware can't handle really short frames, hardware padding works
         * beyond this point
         */
        if (unlikely(skb->len < IAVF_MIN_TX_LEN)) {
                if (skb_pad(skb, IAVF_MIN_TX_LEN - skb->len))
                        return NETDEV_TX_OK;
                skb->len = IAVF_MIN_TX_LEN;
                skb_set_tail_pointer(skb, IAVF_MIN_TX_LEN);
        }

        return iavf_xmit_frame_ring(skb, tx_ring);
}