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

#include <linux/types.h>
#include <linux/module.h>
#include <net/ipv6.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <linux/if_macvlan.h>
#include <linux/prefetch.h>

#include "fm10k.h"

#define DRV_VERSION     "0.26.1-k"
#define DRV_SUMMARY     "Intel(R) Ethernet Switch Host Interface Driver"
const char fm10k_driver_version[] = DRV_VERSION;
char fm10k_driver_name[] = "fm10k";
static const char fm10k_driver_string[] = DRV_SUMMARY;
static const char fm10k_copyright[] =
        "Copyright(c) 2013 - 2018 Intel Corporation.";

MODULE_AUTHOR("Intel Corporation, <linux.nics@intel.com>");
MODULE_DESCRIPTION(DRV_SUMMARY);
MODULE_LICENSE("GPL v2");
MODULE_VERSION(DRV_VERSION);

/* single workqueue for entire fm10k driver */
struct workqueue_struct *fm10k_workqueue;

/**
 * fm10k_init_module - Driver Registration Routine
 *
 * fm10k_init_module is the first routine called when the driver is
 * loaded.  All it does is register with the PCI subsystem.
 **/
static int __init fm10k_init_module(void)
{
        pr_info("%s - version %s\n", fm10k_driver_string, fm10k_driver_version);
        pr_info("%s\n", fm10k_copyright);

        /* create driver workqueue */
        fm10k_workqueue = alloc_workqueue("%s", WQ_MEM_RECLAIM, 0,
                                          fm10k_driver_name);

        fm10k_dbg_init();

        return fm10k_register_pci_driver();
}
module_init(fm10k_init_module);

/**
 * fm10k_exit_module - Driver Exit Cleanup Routine
 *
 * fm10k_exit_module is called just before the driver is removed
 * from memory.
 **/
static void __exit fm10k_exit_module(void)
{
        fm10k_unregister_pci_driver();

        fm10k_dbg_exit();

        /* destroy driver workqueue */
        destroy_workqueue(fm10k_workqueue);
}
module_exit(fm10k_exit_module);

static bool fm10k_alloc_mapped_page(struct fm10k_ring *rx_ring,
                                    struct fm10k_rx_buffer *bi)
{
        struct page *page = bi->page;
        dma_addr_t dma;

        /* Only page will be NULL if buffer was consumed */
        if (likely(page))
                return true;

        /* alloc new page for storage */
        page = dev_alloc_page();
        if (unlikely(!page)) {
                rx_ring->rx_stats.alloc_failed++;
                return false;
        }

        /* map page for use */
        dma = dma_map_page(rx_ring->dev, page, 0, PAGE_SIZE, DMA_FROM_DEVICE);

        /* if mapping failed free memory back to system since
         * there isn't much point in holding memory we can't use
         */
        if (dma_mapping_error(rx_ring->dev, dma)) {
                __free_page(page);

                rx_ring->rx_stats.alloc_failed++;
                return false;
        }

        bi->dma = dma;
        bi->page = page;
        bi->page_offset = 0;

        return true;
}

/**
 * fm10k_alloc_rx_buffers - Replace used receive buffers
 * @rx_ring: ring to place buffers on
 * @cleaned_count: number of buffers to replace
 **/
void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count)
{
        union fm10k_rx_desc *rx_desc;
        struct fm10k_rx_buffer *bi;
        u16 i = rx_ring->next_to_use;

        /* nothing to do */
        if (!cleaned_count)
                return;

        rx_desc = FM10K_RX_DESC(rx_ring, i);
        bi = &rx_ring->rx_buffer[i];
        i -= rx_ring->count;

        do {
                if (!fm10k_alloc_mapped_page(rx_ring, bi))
                        break;

                /* Refresh the desc even if buffer_addrs didn't change
                 * because each write-back erases this info.
                 */
                rx_desc->q.pkt_addr = cpu_to_le64(bi->dma + bi->page_offset);

                rx_desc++;
                bi++;
                i++;
                if (unlikely(!i)) {
                        rx_desc = FM10K_RX_DESC(rx_ring, 0);
                        bi = rx_ring->rx_buffer;
                        i -= rx_ring->count;
                }

                /* clear the status bits for the next_to_use descriptor */
                rx_desc->d.staterr = 0;

                cleaned_count--;
        } while (cleaned_count);

        i += rx_ring->count;

        if (rx_ring->next_to_use != i) {
                /* record the next descriptor to use */
                rx_ring->next_to_use = i;

                /* update next to alloc since we have filled the ring */
                rx_ring->next_to_alloc = i;

                /* 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();

                /* notify hardware of new descriptors */
                writel(i, rx_ring->tail);
        }
}

/**
 * fm10k_reuse_rx_page - page flip buffer and store it back on the ring
 * @rx_ring: rx descriptor ring to store buffers on
 * @old_buff: donor buffer to have page reused
 *
 * Synchronizes page for reuse by the interface
 **/
static void fm10k_reuse_rx_page(struct fm10k_ring *rx_ring,
                                struct fm10k_rx_buffer *old_buff)
{
        struct fm10k_rx_buffer *new_buff;
        u16 nta = rx_ring->next_to_alloc;

        new_buff = &rx_ring->rx_buffer[nta];

        /* update, and store next to alloc */
        nta++;
        rx_ring->next_to_alloc = (nta < rx_ring->count) ? nta : 0;

        /* transfer page from old buffer to new buffer */
        *new_buff = *old_buff;

        /* sync the buffer for use by the device */
        dma_sync_single_range_for_device(rx_ring->dev, old_buff->dma,
                                         old_buff->page_offset,
                                         FM10K_RX_BUFSZ,
                                         DMA_FROM_DEVICE);
}

static inline bool fm10k_page_is_reserved(struct page *page)
{
        return (page_to_nid(page) != numa_mem_id()) || page_is_pfmemalloc(page);
}

static bool fm10k_can_reuse_rx_page(struct fm10k_rx_buffer *rx_buffer,
                                    struct page *page,
                                    unsigned int __maybe_unused truesize)
{
        /* avoid re-using remote pages */
        if (unlikely(fm10k_page_is_reserved(page)))
                return false;

#if (PAGE_SIZE < 8192)
        /* if we are only owner of page we can reuse it */
        if (unlikely(page_count(page) != 1))
                return false;

        /* flip page offset to other buffer */
        rx_buffer->page_offset ^= FM10K_RX_BUFSZ;
#else
        /* move offset up to the next cache line */
        rx_buffer->page_offset += truesize;

        if (rx_buffer->page_offset > (PAGE_SIZE - FM10K_RX_BUFSZ))
                return false;
#endif

        /* Even if we own the page, we are not allowed to use atomic_set()
         * This would break get_page_unless_zero() users.
         */
        page_ref_inc(page);

        return true;
}

/**
 * fm10k_add_rx_frag - Add contents of Rx buffer to sk_buff
 * @rx_buffer: buffer containing page to add
 * @size: packet size from rx_desc
 * @rx_desc: descriptor containing length of buffer written by hardware
 * @skb: sk_buff to place the data into
 *
 * This function will add the data contained in rx_buffer->page to the skb.
 * This is done either through a direct copy if the data in the buffer is
 * less than the skb header size, otherwise it will just attach the page as
 * a frag to the skb.
 *
 * The function will then update the page offset if necessary and return
 * true if the buffer can be reused by the interface.
 **/
static bool fm10k_add_rx_frag(struct fm10k_rx_buffer *rx_buffer,
                              unsigned int size,
                              union fm10k_rx_desc *rx_desc,
                              struct sk_buff *skb)
{
        struct page *page = rx_buffer->page;
        unsigned char *va = page_address(page) + rx_buffer->page_offset;
#if (PAGE_SIZE < 8192)
        unsigned int truesize = FM10K_RX_BUFSZ;
#else
        unsigned int truesize = ALIGN(size, 512);
#endif
        unsigned int pull_len;

        if (unlikely(skb_is_nonlinear(skb)))
                goto add_tail_frag;

        if (likely(size <= FM10K_RX_HDR_LEN)) {
                memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));

                /* page is not reserved, we can reuse buffer as-is */
                if (likely(!fm10k_page_is_reserved(page)))
                        return true;

                /* this page cannot be reused so discard it */
                __free_page(page);
                return false;
        }

        /* we need the header to contain the greater of either ETH_HLEN or
         * 60 bytes if the skb->len is less than 60 for skb_pad.
         */
        pull_len = eth_get_headlen(va, FM10K_RX_HDR_LEN);

        /* align pull length to size of long to optimize memcpy performance */
        memcpy(__skb_put(skb, pull_len), va, ALIGN(pull_len, sizeof(long)));

        /* update all of the pointers */
        va += pull_len;
        size -= pull_len;

add_tail_frag:
        skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
                        (unsigned long)va & ~PAGE_MASK, size, truesize);

        return fm10k_can_reuse_rx_page(rx_buffer, page, truesize);
}

static struct sk_buff *fm10k_fetch_rx_buffer(struct fm10k_ring *rx_ring,
                                             union fm10k_rx_desc *rx_desc,
                                             struct sk_buff *skb)
{
        unsigned int size = le16_to_cpu(rx_desc->w.length);
        struct fm10k_rx_buffer *rx_buffer;
        struct page *page;

        rx_buffer = &rx_ring->rx_buffer[rx_ring->next_to_clean];
        page = rx_buffer->page;
        prefetchw(page);

        if (likely(!skb)) {
                void *page_addr = page_address(page) +
                                  rx_buffer->page_offset;

                /* prefetch first cache line of first page */
                prefetch(page_addr);
#if L1_CACHE_BYTES < 128
                prefetch(page_addr + L1_CACHE_BYTES);
#endif

                /* allocate a skb to store the frags */
                skb = napi_alloc_skb(&rx_ring->q_vector->napi,
                                     FM10K_RX_HDR_LEN);
                if (unlikely(!skb)) {
                        rx_ring->rx_stats.alloc_failed++;
                        return NULL;
                }

                /* we will be copying header into skb->data in
                 * pskb_may_pull so it is in our interest to prefetch
                 * it now to avoid a possible cache miss
                 */
                prefetchw(skb->data);
        }

        /* we are reusing so sync this buffer for CPU use */
        dma_sync_single_range_for_cpu(rx_ring->dev,
                                      rx_buffer->dma,
                                      rx_buffer->page_offset,
                                      size,
                                      DMA_FROM_DEVICE);

        /* pull page into skb */
        if (fm10k_add_rx_frag(rx_buffer, size, rx_desc, skb)) {
                /* hand second half of page back to the ring */
                fm10k_reuse_rx_page(rx_ring, rx_buffer);
        } else {
                /* we are not reusing the buffer so unmap it */
                dma_unmap_page(rx_ring->dev, rx_buffer->dma,
                               PAGE_SIZE, DMA_FROM_DEVICE);
        }

        /* clear contents of rx_buffer */
        rx_buffer->page = NULL;

        return skb;
}

static inline void fm10k_rx_checksum(struct fm10k_ring *ring,
                                     union fm10k_rx_desc *rx_desc,
                                     struct sk_buff *skb)
{
        skb_checksum_none_assert(skb);

        /* Rx checksum disabled via ethtool */
        if (!(ring->netdev->features & NETIF_F_RXCSUM))
                return;

        /* TCP/UDP checksum error bit is set */
        if (fm10k_test_staterr(rx_desc,
                               FM10K_RXD_STATUS_L4E |
                               FM10K_RXD_STATUS_L4E2 |
                               FM10K_RXD_STATUS_IPE |
                               FM10K_RXD_STATUS_IPE2)) {
                ring->rx_stats.csum_err++;
                return;
        }

        /* It must be a TCP or UDP packet with a valid checksum */
        if (fm10k_test_staterr(rx_desc, FM10K_RXD_STATUS_L4CS2))
                skb->encapsulation = true;
        else if (!fm10k_test_staterr(rx_desc, FM10K_RXD_STATUS_L4CS))
                return;

        skb->ip_summed = CHECKSUM_UNNECESSARY;

        ring->rx_stats.csum_good++;
}

#define FM10K_RSS_L4_TYPES_MASK \
        (BIT(FM10K_RSSTYPE_IPV4_TCP) | \
         BIT(FM10K_RSSTYPE_IPV4_UDP) | \
         BIT(FM10K_RSSTYPE_IPV6_TCP) | \
         BIT(FM10K_RSSTYPE_IPV6_UDP))

static inline void fm10k_rx_hash(struct fm10k_ring *ring,
                                 union fm10k_rx_desc *rx_desc,
                                 struct sk_buff *skb)
{
        u16 rss_type;

        if (!(ring->netdev->features & NETIF_F_RXHASH))
                return;

        rss_type = le16_to_cpu(rx_desc->w.pkt_info) & FM10K_RXD_RSSTYPE_MASK;
        if (!rss_type)
                return;

        skb_set_hash(skb, le32_to_cpu(rx_desc->d.rss),
                     (BIT(rss_type) & FM10K_RSS_L4_TYPES_MASK) ?
                     PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
}

static void fm10k_type_trans(struct fm10k_ring *rx_ring,
                             union fm10k_rx_desc __maybe_unused *rx_desc,
                             struct sk_buff *skb)
{
        struct net_device *dev = rx_ring->netdev;
        struct fm10k_l2_accel *l2_accel = rcu_dereference_bh(rx_ring->l2_accel);

        /* check to see if DGLORT belongs to a MACVLAN */
        if (l2_accel) {
                u16 idx = le16_to_cpu(FM10K_CB(skb)->fi.w.dglort) - 1;

                idx -= l2_accel->dglort;
                if (idx < l2_accel->size && l2_accel->macvlan[idx])
                        dev = l2_accel->macvlan[idx];
                else
                        l2_accel = NULL;
        }

        /* Record Rx queue, or update macvlan statistics */
        if (!l2_accel)
                skb_record_rx_queue(skb, rx_ring->queue_index);
        else
                macvlan_count_rx(netdev_priv(dev), skb->len + ETH_HLEN, true,
                                 false);

        skb->protocol = eth_type_trans(skb, dev);
}

/**
 * fm10k_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
 *
 * This function checks the ring, descriptor, and packet information in
 * order to populate the hash, checksum, VLAN, timestamp, protocol, and
 * other fields within the skb.
 **/
static unsigned int fm10k_process_skb_fields(struct fm10k_ring *rx_ring,
                                             union fm10k_rx_desc *rx_desc,
                                             struct sk_buff *skb)
{
        unsigned int len = skb->len;

        fm10k_rx_hash(rx_ring, rx_desc, skb);

        fm10k_rx_checksum(rx_ring, rx_desc, skb);

        FM10K_CB(skb)->tstamp = rx_desc->q.timestamp;

        FM10K_CB(skb)->fi.w.vlan = rx_desc->w.vlan;

        FM10K_CB(skb)->fi.d.glort = rx_desc->d.glort;

        if (rx_desc->w.vlan) {
                u16 vid = le16_to_cpu(rx_desc->w.vlan);

                if ((vid & VLAN_VID_MASK) != rx_ring->vid)
                        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vid);
                else if (vid & VLAN_PRIO_MASK)
                        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                               vid & VLAN_PRIO_MASK);
        }

        fm10k_type_trans(rx_ring, rx_desc, skb);

        return len;
}

/**
 * fm10k_is_non_eop - process handling of non-EOP buffers
 * @rx_ring: Rx ring being processed
 * @rx_desc: Rx descriptor for current buffer
 *
 * 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 fm10k_is_non_eop(struct fm10k_ring *rx_ring,
                             union fm10k_rx_desc *rx_desc)
{
        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(FM10K_RX_DESC(rx_ring, ntc));

        if (likely(fm10k_test_staterr(rx_desc, FM10K_RXD_STATUS_EOP)))
                return false;

        return true;
}

/**
 * fm10k_cleanup_headers - Correct corrupted or empty headers
 * @rx_ring: rx descriptor ring packet is being transacted on
 * @rx_desc: pointer to the EOP Rx descriptor
 * @skb: pointer to current skb being fixed
 *
 * 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 fm10k_cleanup_headers(struct fm10k_ring *rx_ring,
                                  union fm10k_rx_desc *rx_desc,
                                  struct sk_buff *skb)
{
        if (unlikely((fm10k_test_staterr(rx_desc,
                                         FM10K_RXD_STATUS_RXE)))) {
#define FM10K_TEST_RXD_BIT(rxd, bit) \
        ((rxd)->w.csum_err & cpu_to_le16(bit))
                if (FM10K_TEST_RXD_BIT(rx_desc, FM10K_RXD_ERR_SWITCH_ERROR))
                        rx_ring->rx_stats.switch_errors++;
                if (FM10K_TEST_RXD_BIT(rx_desc, FM10K_RXD_ERR_NO_DESCRIPTOR))
                        rx_ring->rx_stats.drops++;
                if (FM10K_TEST_RXD_BIT(rx_desc, FM10K_RXD_ERR_PP_ERROR))
                        rx_ring->rx_stats.pp_errors++;
                if (FM10K_TEST_RXD_BIT(rx_desc, FM10K_RXD_ERR_SWITCH_READY))
                        rx_ring->rx_stats.link_errors++;
                if (FM10K_TEST_RXD_BIT(rx_desc, FM10K_RXD_ERR_TOO_BIG))
                        rx_ring->rx_stats.length_errors++;
                dev_kfree_skb_any(skb);
                rx_ring->rx_stats.errors++;
                return true;
        }

        /* if eth_skb_pad returns an error the skb was freed */
        if (eth_skb_pad(skb))
                return true;

        return false;
}

/**
 * fm10k_receive_skb - helper function to handle rx indications
 * @q_vector: structure containing interrupt and ring information
 * @skb: packet to send up
 **/
static void fm10k_receive_skb(struct fm10k_q_vector *q_vector,
                              struct sk_buff *skb)
{
        napi_gro_receive(&q_vector->napi, skb);
}

static int fm10k_clean_rx_irq(struct fm10k_q_vector *q_vector,
                              struct fm10k_ring *rx_ring,
                              int budget)
{
        struct sk_buff *skb = rx_ring->skb;
        unsigned int total_bytes = 0, total_packets = 0;
        u16 cleaned_count = fm10k_desc_unused(rx_ring);

        while (likely(total_packets < budget)) {
                union fm10k_rx_desc *rx_desc;

                /* return some buffers to hardware, one at a time is too slow */
                if (cleaned_count >= FM10K_RX_BUFFER_WRITE) {
                        fm10k_alloc_rx_buffers(rx_ring, cleaned_count);
                        cleaned_count = 0;
                }

                rx_desc = FM10K_RX_DESC(rx_ring, rx_ring->next_to_clean);

                if (!rx_desc->d.staterr)
                        break;

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

                /* retrieve a buffer from the ring */
                skb = fm10k_fetch_rx_buffer(rx_ring, rx_desc, skb);

                /* exit if we failed to retrieve a buffer */
                if (!skb)
                        break;

                cleaned_count++;

                /* fetch next buffer in frame if non-eop */
                if (fm10k_is_non_eop(rx_ring, rx_desc))
                        continue;

                /* verify the packet layout is correct */
                if (fm10k_cleanup_headers(rx_ring, rx_desc, skb)) {
                        skb = NULL;
                        continue;
                }

                /* populate checksum, timestamp, VLAN, and protocol */
                total_bytes += fm10k_process_skb_fields(rx_ring, rx_desc, skb);

                fm10k_receive_skb(q_vector, skb);

                /* reset skb pointer */
                skb = NULL;

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

        /* place incomplete frames back on ring for completion */
        rx_ring->skb = skb;

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

        return total_packets;
}

#define VXLAN_HLEN (sizeof(struct udphdr) + 8)
static struct ethhdr *fm10k_port_is_vxlan(struct sk_buff *skb)
{
        struct fm10k_intfc *interface = netdev_priv(skb->dev);
        struct fm10k_udp_port *vxlan_port;

        /* we can only offload a vxlan if we recognize it as such */
        vxlan_port = list_first_entry_or_null(&interface->vxlan_port,
                                              struct fm10k_udp_port, list);

        if (!vxlan_port)
                return NULL;
        if (vxlan_port->port != udp_hdr(skb)->dest)
                return NULL;

        /* return offset of udp_hdr plus 8 bytes for VXLAN header */
        return (struct ethhdr *)(skb_transport_header(skb) + VXLAN_HLEN);
}

#define FM10K_NVGRE_RESERVED0_FLAGS htons(0x9FFF)
#define NVGRE_TNI htons(0x2000)
struct fm10k_nvgre_hdr {
        __be16 flags;
        __be16 proto;
        __be32 tni;
};

static struct ethhdr *fm10k_gre_is_nvgre(struct sk_buff *skb)
{
        struct fm10k_nvgre_hdr *nvgre_hdr;
        int hlen = ip_hdrlen(skb);

        /* currently only IPv4 is supported due to hlen above */
        if (vlan_get_protocol(skb) != htons(ETH_P_IP))
                return NULL;

        /* our transport header should be NVGRE */
        nvgre_hdr = (struct fm10k_nvgre_hdr *)(skb_network_header(skb) + hlen);

        /* verify all reserved flags are 0 */
        if (nvgre_hdr->flags & FM10K_NVGRE_RESERVED0_FLAGS)
                return NULL;

        /* report start of ethernet header */
        if (nvgre_hdr->flags & NVGRE_TNI)
                return (struct ethhdr *)(nvgre_hdr + 1);

        return (struct ethhdr *)(&nvgre_hdr->tni);
}

__be16 fm10k_tx_encap_offload(struct sk_buff *skb)
{
        u8 l4_hdr = 0, inner_l4_hdr = 0, inner_l4_hlen;
        struct ethhdr *eth_hdr;

        if (skb->inner_protocol_type != ENCAP_TYPE_ETHER ||
            skb->inner_protocol != htons(ETH_P_TEB))
                return 0;

        switch (vlan_get_protocol(skb)) {
        case htons(ETH_P_IP):
                l4_hdr = ip_hdr(skb)->protocol;
                break;
        case htons(ETH_P_IPV6):
                l4_hdr = ipv6_hdr(skb)->nexthdr;
                break;
        default:
                return 0;
        }

        switch (l4_hdr) {
        case IPPROTO_UDP:
                eth_hdr = fm10k_port_is_vxlan(skb);
                break;
        case IPPROTO_GRE:
                eth_hdr = fm10k_gre_is_nvgre(skb);
                break;
        default:
                return 0;
        }

        if (!eth_hdr)
                return 0;

        switch (eth_hdr->h_proto) {
        case htons(ETH_P_IP):
                inner_l4_hdr = inner_ip_hdr(skb)->protocol;
                break;
        case htons(ETH_P_IPV6):
                inner_l4_hdr = inner_ipv6_hdr(skb)->nexthdr;
                break;
        default:
                return 0;
        }

        switch (inner_l4_hdr) {
        case IPPROTO_TCP:
                inner_l4_hlen = inner_tcp_hdrlen(skb);
                break;
        case IPPROTO_UDP:
                inner_l4_hlen = 8;
                break;
        default:
                return 0;
        }

        /* The hardware allows tunnel offloads only if the combined inner and
         * outer header is 184 bytes or less
         */
        if (skb_inner_transport_header(skb) + inner_l4_hlen -
            skb_mac_header(skb) > FM10K_TUNNEL_HEADER_LENGTH)
                return 0;

        return eth_hdr->h_proto;
}

static int fm10k_tso(struct fm10k_ring *tx_ring,
                     struct fm10k_tx_buffer *first)
{
        struct sk_buff *skb = first->skb;
        struct fm10k_tx_desc *tx_desc;
        unsigned char *th;
        u8 hdrlen;

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

        if (!skb_is_gso(skb))
                return 0;

        /* compute header lengths */
        if (skb->encapsulation) {
                if (!fm10k_tx_encap_offload(skb))
                        goto err_vxlan;
                th = skb_inner_transport_header(skb);
        } else {
                th = skb_transport_header(skb);
        }

        /* compute offset from SOF to transport header and add header len */
        hdrlen = (th - skb->data) + (((struct tcphdr *)th)->doff << 2);

        first->tx_flags |= FM10K_TX_FLAGS_CSUM;

        /* update gso size and bytecount with header size */
        first->gso_segs = skb_shinfo(skb)->gso_segs;
        first->bytecount += (first->gso_segs - 1) * hdrlen;

        /* populate Tx descriptor header size and mss */
        tx_desc = FM10K_TX_DESC(tx_ring, tx_ring->next_to_use);
        tx_desc->hdrlen = hdrlen;
        tx_desc->mss = cpu_to_le16(skb_shinfo(skb)->gso_size);

        return 1;

err_vxlan:
        tx_ring->netdev->features &= ~NETIF_F_GSO_UDP_TUNNEL;
        if (net_ratelimit())
                netdev_err(tx_ring->netdev,
                           "TSO requested for unsupported tunnel, disabling offload\n");
        return -1;
}

static void fm10k_tx_csum(struct fm10k_ring *tx_ring,
                          struct fm10k_tx_buffer *first)
{
        struct sk_buff *skb = first->skb;
        struct fm10k_tx_desc *tx_desc;
        union {
                struct iphdr *ipv4;
                struct ipv6hdr *ipv6;
                u8 *raw;
        } network_hdr;
        u8 *transport_hdr;
        __be16 frag_off;
        __be16 protocol;
        u8 l4_hdr = 0;

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                goto no_csum;

        if (skb->encapsulation) {
                protocol = fm10k_tx_encap_offload(skb);
                if (!protocol) {
                        if (skb_checksum_help(skb)) {
                                dev_warn(tx_ring->dev,
                                         "failed to offload encap csum!\n");
                                tx_ring->tx_stats.csum_err++;
                        }
                        goto no_csum;
                }
                network_hdr.raw = skb_inner_network_header(skb);
                transport_hdr = skb_inner_transport_header(skb);
        } else {
                protocol = vlan_get_protocol(skb);
                network_hdr.raw = skb_network_header(skb);
                transport_hdr = skb_transport_header(skb);
        }

        switch (protocol) {
        case htons(ETH_P_IP):
                l4_hdr = network_hdr.ipv4->protocol;
                break;
        case htons(ETH_P_IPV6):
                l4_hdr = network_hdr.ipv6->nexthdr;
                if (likely((transport_hdr - network_hdr.raw) ==
                           sizeof(struct ipv6hdr)))
                        break;
                ipv6_skip_exthdr(skb, network_hdr.raw - skb->data +
                                      sizeof(struct ipv6hdr),
                                 &l4_hdr, &frag_off);
                if (unlikely(frag_off))
                        l4_hdr = NEXTHDR_FRAGMENT;
                break;
        default:
                break;
        }

        switch (l4_hdr) {
        case IPPROTO_TCP:
        case IPPROTO_UDP:
                break;
        case IPPROTO_GRE:
                if (skb->encapsulation)
                        break;
                /* fall through */
        default:
                if (unlikely(net_ratelimit())) {
                        dev_warn(tx_ring->dev,
                                 "partial checksum, version=%d l4 proto=%x\n",
                                 protocol, l4_hdr);
                }
                skb_checksum_help(skb);
                tx_ring->tx_stats.csum_err++;
                goto no_csum;
        }

        /* update TX checksum flag */
        first->tx_flags |= FM10K_TX_FLAGS_CSUM;
        tx_ring->tx_stats.csum_good++;

no_csum:
        /* populate Tx descriptor header size and mss */
        tx_desc = FM10K_TX_DESC(tx_ring, tx_ring->next_to_use);
        tx_desc->hdrlen = 0;
        tx_desc->mss = 0;
}

#define FM10K_SET_FLAG(_input, _flag, _result) \
        ((_flag <= _result) ? \
         ((u32)(_input & _flag) * (_result / _flag)) : \
         ((u32)(_input & _flag) / (_flag / _result)))

static u8 fm10k_tx_desc_flags(struct sk_buff *skb, u32 tx_flags)
{
        /* set type for advanced descriptor with frame checksum insertion */
        u32 desc_flags = 0;

        /* set checksum offload bits */
        desc_flags |= FM10K_SET_FLAG(tx_flags, FM10K_TX_FLAGS_CSUM,
                                     FM10K_TXD_FLAG_CSUM);

        return desc_flags;
}

static bool fm10k_tx_desc_push(struct fm10k_ring *tx_ring,
                               struct fm10k_tx_desc *tx_desc, u16 i,
                               dma_addr_t dma, unsigned int size, u8 desc_flags)
{
        /* set RS and INT for last frame in a cache line */
        if ((++i & (FM10K_TXD_WB_FIFO_SIZE - 1)) == 0)
                desc_flags |= FM10K_TXD_FLAG_RS | FM10K_TXD_FLAG_INT;

        /* record values to descriptor */
        tx_desc->buffer_addr = cpu_to_le64(dma);
        tx_desc->flags = desc_flags;
        tx_desc->buflen = cpu_to_le16(size);

        /* return true if we just wrapped the ring */
        return i == tx_ring->count;
}

static int __fm10k_maybe_stop_tx(struct fm10k_ring *tx_ring, u16 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(fm10k_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;
}

static inline int fm10k_maybe_stop_tx(struct fm10k_ring *tx_ring, u16 size)
{
        if (likely(fm10k_desc_unused(tx_ring) >= size))
                return 0;
        return __fm10k_maybe_stop_tx(tx_ring, size);
}

static void fm10k_tx_map(struct fm10k_ring *tx_ring,
                         struct fm10k_tx_buffer *first)
{
        struct sk_buff *skb = first->skb;
        struct fm10k_tx_buffer *tx_buffer;
        struct fm10k_tx_desc *tx_desc;
        struct skb_frag_struct *frag;
        unsigned char *data;
        dma_addr_t dma;
        unsigned int data_len, size;
        u32 tx_flags = first->tx_flags;
        u16 i = tx_ring->next_to_use;
        u8 flags = fm10k_tx_desc_flags(skb, tx_flags);

        tx_desc = FM10K_TX_DESC(tx_ring, i);

        /* add HW VLAN tag */
        if (skb_vlan_tag_present(skb))
                tx_desc->vlan = cpu_to_le16(skb_vlan_tag_get(skb));
        else
                tx_desc->vlan = 0;

        size = skb_headlen(skb);
        data = skb->data;

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

        data_len = skb->data_len;
        tx_buffer = first;

        for (frag = &skb_shinfo(skb)->frags[0];; frag++) {
                if (dma_mapping_error(tx_ring->dev, dma))
                        goto dma_error;

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

                while (unlikely(size > FM10K_MAX_DATA_PER_TXD)) {
                        if (fm10k_tx_desc_push(tx_ring, tx_desc++, i++, dma,
                                               FM10K_MAX_DATA_PER_TXD, flags)) {
                                tx_desc = FM10K_TX_DESC(tx_ring, 0);
                                i = 0;
                        }

                        dma += FM10K_MAX_DATA_PER_TXD;
                        size -= FM10K_MAX_DATA_PER_TXD;
                }

                if (likely(!data_len))
                        break;

                if (fm10k_tx_desc_push(tx_ring, tx_desc++, i++,
                                       dma, size, flags)) {
                        tx_desc = FM10K_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_buffer = &tx_ring->tx_buffer[i];
        }

        /* write last descriptor with LAST bit set */
        flags |= FM10K_TXD_FLAG_LAST;

        if (fm10k_tx_desc_push(tx_ring, tx_desc, i++, dma, size, flags))
                i = 0;

        /* record bytecount for BQL */
        netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);

        /* record SW timestamp if HW timestamp is not available */
        skb_tx_timestamp(first->skb);

        /* 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).
         *
         * We also need 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;

        tx_ring->next_to_use = i;

        /* Make sure there is space in the ring for the next send. */
        fm10k_maybe_stop_tx(tx_ring, DESC_NEEDED);

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

                /* we need this if more than one processor can write to our tail
                 * at a time, it synchronizes IO on IA64/Altix systems
                 */
                mmiowb();
        }

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

        /* clear dma mappings for failed tx_buffer map */
        for (;;) {
                tx_buffer = &tx_ring->tx_buffer[i];
                fm10k_unmap_and_free_tx_resource(tx_ring, tx_buffer);
                if (tx_buffer == first)
                        break;
                if (i == 0)
                        i = tx_ring->count;
                i--;
        }

        tx_ring->next_to_use = i;
}

netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb,
                                  struct fm10k_ring *tx_ring)
{
        u16 count = TXD_USE_COUNT(skb_headlen(skb));
        struct fm10k_tx_buffer *first;
        unsigned short f;
        u32 tx_flags = 0;
        int tso;

        /* need: 1 descriptor per page * PAGE_SIZE/FM10K_MAX_DATA_PER_TXD,
         *       + 1 desc for skb_headlen/FM10K_MAX_DATA_PER_TXD,
         *       + 2 desc gap to keep tail from touching head
         * otherwise try next time
         */
        for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
                count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size);

        if (fm10k_maybe_stop_tx(tx_ring, count + 3)) {
                tx_ring->tx_stats.tx_busy++;
                return NETDEV_TX_BUSY;
        }

        /* record the location of the first descriptor for this packet */
        first = &tx_ring->tx_buffer[tx_ring->next_to_use];
        first->skb = skb;
        first->bytecount = max_t(unsigned int, skb->len, ETH_ZLEN);
        first->gso_segs = 1;

        /* record initial flags and protocol */
        first->tx_flags = tx_flags;

        tso = fm10k_tso(tx_ring, first);
        if (tso < 0)
                goto out_drop;
        else if (!tso)
                fm10k_tx_csum(tx_ring, first);

        fm10k_tx_map(tx_ring, first);

        return NETDEV_TX_OK;

out_drop:
        dev_kfree_skb_any(first->skb);
        first->skb = NULL;

        return NETDEV_TX_OK;
}

static u64 fm10k_get_tx_completed(struct fm10k_ring *ring)
{
        return ring->stats.packets;
}

/**
 * fm10k_get_tx_pending - how many Tx descriptors not processed
 * @ring: the ring structure
 * @in_sw: is tx_pending being checked in SW or in HW?
 */
u64 fm10k_get_tx_pending(struct fm10k_ring *ring, bool in_sw)
{
        struct fm10k_intfc *interface = ring->q_vector->interface;
        struct fm10k_hw *hw = &interface->hw;
        u32 head, tail;

        if (likely(in_sw)) {
                head = ring->next_to_clean;
                tail = ring->next_to_use;
        } else {
                head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx));
                tail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx));
        }

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

bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring)
{
        u32 tx_done = fm10k_get_tx_completed(tx_ring);
        u32 tx_done_old = tx_ring->tx_stats.tx_done_old;
        u32 tx_pending = fm10k_get_tx_pending(tx_ring, true);

        clear_check_for_tx_hang(tx_ring);

        /* Check for a hung queue, but be thorough. This verifies
         * that a transmit has been completed since the previous
         * check AND there is at least one packet pending. By
         * requiring this to fail twice we avoid races with
         * clearing the ARMED bit and conditions where we
         * run the check_tx_hang logic with a transmit completion
         * pending but without time to complete it yet.
         */
        if (!tx_pending || (tx_done_old != tx_done)) {
                /* update completed stats and continue */
                tx_ring->tx_stats.tx_done_old = tx_done;
                /* reset the countdown */
                clear_bit(__FM10K_HANG_CHECK_ARMED, tx_ring->state);

                return false;
        }

        /* make sure it is true for two checks in a row */
        return test_and_set_bit(__FM10K_HANG_CHECK_ARMED, tx_ring->state);
}

/**
 * fm10k_tx_timeout_reset - initiate reset due to Tx timeout
 * @interface: driver private struct
 **/
void fm10k_tx_timeout_reset(struct fm10k_intfc *interface)
{
        /* Do the reset outside of interrupt context */
        if (!test_bit(__FM10K_DOWN, interface->state)) {
                interface->tx_timeout_count++;
                set_bit(FM10K_FLAG_RESET_REQUESTED, interface->flags);
                fm10k_service_event_schedule(interface);
        }
}

/**
 * fm10k_clean_tx_irq - Reclaim resources after transmit completes
 * @q_vector: structure containing interrupt and ring information
 * @tx_ring: tx ring to clean
 * @napi_budget: Used to determine if we are in netpoll
 **/
static bool fm10k_clean_tx_irq(struct fm10k_q_vector *q_vector,
                               struct fm10k_ring *tx_ring, int napi_budget)
{
        struct fm10k_intfc *interface = q_vector->interface;
        struct fm10k_tx_buffer *tx_buffer;
        struct fm10k_tx_desc *tx_desc;
        unsigned int total_bytes = 0, total_packets = 0;
        unsigned int budget = q_vector->tx.work_limit;
        unsigned int i = tx_ring->next_to_clean;

        if (test_bit(__FM10K_DOWN, interface->state))
                return true;

        tx_buffer = &tx_ring->tx_buffer[i];
        tx_desc = FM10K_TX_DESC(tx_ring, i);
        i -= tx_ring->count;

        do {
                struct fm10k_tx_desc *eop_desc = tx_buffer->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();

                /* if DD is not set pending work has not been completed */
                if (!(eop_desc->flags & FM10K_TXD_FLAG_DONE))
                        break;

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

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

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

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

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

                /* unmap remaining buffers */
                while (tx_desc != eop_desc) {
                        tx_buffer++;
                        tx_desc++;
                        i++;
                        if (unlikely(!i)) {
                                i -= tx_ring->count;
                                tx_buffer = tx_ring->tx_buffer;
                                tx_desc = FM10K_TX_DESC(tx_ring, 0);
                        }

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

                /* move us one more past the eop_desc for start of next pkt */
                tx_buffer++;
                tx_desc++;
                i++;
                if (unlikely(!i)) {
                        i -= tx_ring->count;
                        tx_buffer = tx_ring->tx_buffer;
                        tx_desc = FM10K_TX_DESC(tx_ring, 0);
                }

                /* issue prefetch for next Tx descriptor */
                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);
        q_vector->tx.total_bytes += total_bytes;
        q_vector->tx.total_packets += total_packets;

        if (check_for_tx_hang(tx_ring) && fm10k_check_tx_hang(tx_ring)) {
                /* schedule immediate reset if we believe we hung */
                struct fm10k_hw *hw = &interface->hw;

                netif_err(interface, drv, tx_ring->netdev,
                          "Detected Tx Unit Hang\n"
                          "  Tx Queue             <%d>\n"
                          "  TDH, TDT             <%x>, <%x>\n"
                          "  next_to_use          <%x>\n"
                          "  next_to_clean        <%x>\n",
                          tx_ring->queue_index,
                          fm10k_read_reg(hw, FM10K_TDH(tx_ring->reg_idx)),
                          fm10k_read_reg(hw, FM10K_TDT(tx_ring->reg_idx)),
                          tx_ring->next_to_use, i);

                netif_stop_subqueue(tx_ring->netdev,
                                    tx_ring->queue_index);

                netif_info(interface, probe, tx_ring->netdev,
                           "tx hang %d detected on queue %d, resetting interface\n",
                           interface->tx_timeout_count + 1,
                           tx_ring->queue_index);

                fm10k_tx_timeout_reset(interface);

                /* the netdev is about to reset, no point in enabling stuff */
                return true;
        }

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

#define TX_WAKE_THRESHOLD min_t(u16, FM10K_MIN_TXD - 1, DESC_NEEDED * 2)
        if (unlikely(total_packets && netif_carrier_ok(tx_ring->netdev) &&
                     (fm10k_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(__FM10K_DOWN, interface->state)) {
                        netif_wake_subqueue(tx_ring->netdev,
                                            tx_ring->queue_index);
                        ++tx_ring->tx_stats.restart_queue;
                }
        }

        return !!budget;
}

/**
 * fm10k_update_itr - update the dynamic ITR value based on packet size
 *
 *      Stores a new ITR value based on strictly on packet size.  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.
 *
 * @ring_container: Container for rings to have ITR updated
 **/
static void fm10k_update_itr(struct fm10k_ring_container *ring_container)
{
        unsigned int avg_wire_size, packets, itr_round;

        /* Only update ITR if we are using adaptive setting */
        if (!ITR_IS_ADAPTIVE(ring_container->itr))
                goto clear_counts;

        packets = ring_container->total_packets;
        if (!packets)
                goto clear_counts;

        avg_wire_size = ring_container->total_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
         *
         *  (34 * (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 <= 360) {
                /* Start at 250K ints/sec and gradually drop to 77K ints/sec */
                avg_wire_size *= 8;
                avg_wire_size += 376;
        } else if (avg_wire_size <= 1152) {
                /* 77K ints/sec to 45K ints/sec */
                avg_wire_size *= 3;
                avg_wire_size += 2176;
        } else if (avg_wire_size <= 1920) {
                /* 45K ints/sec to 38K ints/sec */
                avg_wire_size += 4480;
        } else {
                /* plateau at a limit of 38K ints/sec */
                avg_wire_size = 6656;
        }

        /* Perform final bitshift for division after rounding up to ensure
         * that the calculation will never get below a 1. The bit shift
         * accounts for changes in the ITR due to PCIe link speed.
         */
        itr_round = READ_ONCE(ring_container->itr_scale) + 8;
        avg_wire_size += BIT(itr_round) - 1;
        avg_wire_size >>= itr_round;

        /* write back value and retain adaptive flag */
        ring_container->itr = avg_wire_size | FM10K_ITR_ADAPTIVE;

clear_counts:
        ring_container->total_bytes = 0;
        ring_container->total_packets = 0;
}

static void fm10k_qv_enable(struct fm10k_q_vector *q_vector)
{
        /* Enable auto-mask and clear the current mask */
        u32 itr = FM10K_ITR_ENABLE;

        /* Update Tx ITR */
        fm10k_update_itr(&q_vector->tx);

        /* Update Rx ITR */
        fm10k_update_itr(&q_vector->rx);

        /* Store Tx itr in timer slot 0 */
        itr |= (q_vector->tx.itr & FM10K_ITR_MAX);

        /* Shift Rx itr to timer slot 1 */
        itr |= (q_vector->rx.itr & FM10K_ITR_MAX) << FM10K_ITR_INTERVAL1_SHIFT;

        /* Write the final value to the ITR register */
        writel(itr, q_vector->itr);
}

static int fm10k_poll(struct napi_struct *napi, int budget)
{
        struct fm10k_q_vector *q_vector =
                               container_of(napi, struct fm10k_q_vector, napi);
        struct fm10k_ring *ring;
        int per_ring_budget, work_done = 0;
        bool clean_complete = true;

        fm10k_for_each_ring(ring, q_vector->tx) {
                if (!fm10k_clean_tx_irq(q_vector, ring, budget))
                        clean_complete = false;
        }

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

        /* attempt to distribute budget to each queue fairly, but don't
         * allow the budget to go below 1 because we'll exit polling
         */
        if (q_vector->rx.count > 1)
                per_ring_budget = max(budget / q_vector->rx.count, 1);
        else
                per_ring_budget = budget;

        fm10k_for_each_ring(ring, q_vector->rx) {
                int work = fm10k_clean_rx_irq(q_vector, ring, per_ring_budget);

                work_done += work;
                if (work >= per_ring_budget)
                        clean_complete = false;
        }

        /* If all work not completed, return budget and keep polling */
        if (!clean_complete)
                return budget;

        /* all work done, exit the polling mode */
        napi_complete_done(napi, work_done);

        /* re-enable the q_vector */
        fm10k_qv_enable(q_vector);

        return min(work_done, budget - 1);
}

/**
 * fm10k_set_qos_queues: Allocate queues for a QOS-enabled device
 * @interface: board private structure to initialize
 *
 * When QoS (Quality of Service) is enabled, allocate queues for
 * each traffic class.  If multiqueue isn't available,then abort QoS
 * initialization.
 *
 * This function handles all combinations of Qos and RSS.
 *
 **/
static bool fm10k_set_qos_queues(struct fm10k_intfc *interface)
{
        struct net_device *dev = interface->netdev;
        struct fm10k_ring_feature *f;
        int rss_i, i;
        int pcs;

        /* Map queue offset and counts onto allocated tx queues */
        pcs = netdev_get_num_tc(dev);

        if (pcs <= 1)
                return false;

        /* set QoS mask and indices */
        f = &interface->ring_feature[RING_F_QOS];
        f->indices = pcs;
        f->mask = BIT(fls(pcs - 1)) - 1;

        /* determine the upper limit for our current DCB mode */
        rss_i = interface->hw.mac.max_queues / pcs;
        rss_i = BIT(fls(rss_i) - 1);

        /* set RSS mask and indices */
        f = &interface->ring_feature[RING_F_RSS];
        rss_i = min_t(u16, rss_i, f->limit);
        f->indices = rss_i;
        f->mask = BIT(fls(rss_i - 1)) - 1;

        /* configure pause class to queue mapping */
        for (i = 0; i < pcs; i++)
                netdev_set_tc_queue(dev, i, rss_i, rss_i * i);

        interface->num_rx_queues = rss_i * pcs;
        interface->num_tx_queues = rss_i * pcs;

        return true;
}

/**
 * fm10k_set_rss_queues: Allocate queues for RSS
 * @interface: board private structure to initialize
 *
 * This is our "base" multiqueue mode.  RSS (Receive Side Scaling) will try
 * to allocate one Rx queue per CPU, and if available, one Tx queue per CPU.
 *
 **/
static bool fm10k_set_rss_queues(struct fm10k_intfc *interface)
{
        struct fm10k_ring_feature *f;
        u16 rss_i;

        f = &interface->ring_feature[RING_F_RSS];
        rss_i = min_t(u16, interface->hw.mac.max_queues, f->limit);

        /* record indices and power of 2 mask for RSS */
        f->indices = rss_i;
        f->mask = BIT(fls(rss_i - 1)) - 1;

        interface->num_rx_queues = rss_i;
        interface->num_tx_queues = rss_i;

        return true;
}

/**
 * fm10k_set_num_queues: Allocate queues for device, feature dependent
 * @interface: board private structure to initialize
 *
 * This is the top level queue allocation routine.  The order here is very
 * important, starting with the "most" number of features turned on at once,
 * and ending with the smallest set of features.  This way large combinations
 * can be allocated if they're turned on, and smaller combinations are the
 * fallthrough conditions.
 *
 **/
static void fm10k_set_num_queues(struct fm10k_intfc *interface)
{
        /* Attempt to setup QoS and RSS first */
        if (fm10k_set_qos_queues(interface))
                return;

        /* If we don't have QoS, just fallback to only RSS. */
        fm10k_set_rss_queues(interface);
}

/**
 * fm10k_reset_num_queues - Reset the number of queues to zero
 * @interface: board private structure
 *
 * This function should be called whenever we need to reset the number of
 * queues after an error condition.
 */
static void fm10k_reset_num_queues(struct fm10k_intfc *interface)
{
        interface->num_tx_queues = 0;
        interface->num_rx_queues = 0;
        interface->num_q_vectors = 0;
}

/**
 * fm10k_alloc_q_vector - Allocate memory for a single interrupt vector
 * @interface: board private structure to initialize
 * @v_count: q_vectors allocated on interface, used for ring interleaving
 * @v_idx: index of vector in interface 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 fm10k_alloc_q_vector(struct fm10k_intfc *interface,
                                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 fm10k_q_vector *q_vector;
        struct fm10k_ring *ring;
        int ring_count, size;

        ring_count = txr_count + rxr_count;
        size = sizeof(struct fm10k_q_vector) +
               (sizeof(struct fm10k_ring) * ring_count);

        /* allocate q_vector and rings */
        q_vector = kzalloc(size, GFP_KERNEL);
        if (!q_vector)
                return -ENOMEM;

        /* initialize NAPI */
        netif_napi_add(interface->netdev, &q_vector->napi,
                       fm10k_poll, NAPI_POLL_WEIGHT);

        /* tie q_vector and interface together */
        interface->q_vector[v_idx] = q_vector;
        q_vector->interface = interface;
        q_vector->v_idx = v_idx;

        /* initialize pointer to rings */
        ring = q_vector->ring;

        /* save Tx ring container info */
        q_vector->tx.ring = ring;
        q_vector->tx.work_limit = FM10K_DEFAULT_TX_WORK;
        q_vector->tx.itr = interface->tx_itr;
        q_vector->tx.itr_scale = interface->hw.mac.itr_scale;
        q_vector->tx.count = txr_count;

        while (txr_count) {
                /* assign generic ring traits */
                ring->dev = &interface->pdev->dev;
                ring->netdev = interface->netdev;

                /* configure backlink on ring */
                ring->q_vector = q_vector;

                /* apply Tx specific ring traits */
                ring->count = interface->tx_ring_count;
                ring->queue_index = txr_idx;

                /* assign ring to interface */
                interface->tx_ring[txr_idx] = ring;

                /* update count and index */
                txr_count--;
                txr_idx += v_count;

                /* push pointer to next ring */
                ring++;
        }

        /* save Rx ring container info */
        q_vector->rx.ring = ring;
        q_vector->rx.itr = interface->rx_itr;
        q_vector->rx.itr_scale = interface->hw.mac.itr_scale;
        q_vector->rx.count = rxr_count;

        while (rxr_count) {
                /* assign generic ring traits */
                ring->dev = &interface->pdev->dev;
                ring->netdev = interface->netdev;
                rcu_assign_pointer(ring->l2_accel, interface->l2_accel);

                /* configure backlink on ring */
                ring->q_vector = q_vector;

                /* apply Rx specific ring traits */
                ring->count = interface->rx_ring_count;
                ring->queue_index = rxr_idx;

                /* assign ring to interface */
                interface->rx_ring[rxr_idx] = ring;

                /* update count and index */
                rxr_count--;
                rxr_idx += v_count;

                /* push pointer to next ring */
                ring++;
        }

        fm10k_dbg_q_vector_init(q_vector);

        return 0;
}

/**
 * fm10k_free_q_vector - Free memory allocated for specific interrupt vector
 * @interface: board private structure to initialize
 * @v_idx: Index of vector to be freed
 *
 * This function frees the memory allocated to the q_vector.  In addition if
 * NAPI is enabled it will delete any references to the NAPI struct prior
 * to freeing the q_vector.
 **/
static void fm10k_free_q_vector(struct fm10k_intfc *interface, int v_idx)
{
        struct fm10k_q_vector *q_vector = interface->q_vector[v_idx];
        struct fm10k_ring *ring;

        fm10k_dbg_q_vector_exit(q_vector);

        fm10k_for_each_ring(ring, q_vector->tx)
                interface->tx_ring[ring->queue_index] = NULL;

        fm10k_for_each_ring(ring, q_vector->rx)
                interface->rx_ring[ring->queue_index] = NULL;

        interface->q_vector[v_idx] = NULL;
        netif_napi_del(&q_vector->napi);
        kfree_rcu(q_vector, rcu);
}

/**
 * fm10k_alloc_q_vectors - Allocate memory for interrupt vectors
 * @interface: board private structure to initialize
 *
 * We allocate one q_vector per queue interrupt.  If allocation fails we
 * return -ENOMEM.
 **/
static int fm10k_alloc_q_vectors(struct fm10k_intfc *interface)
{
        unsigned int q_vectors = interface->num_q_vectors;
        unsigned int rxr_remaining = interface->num_rx_queues;
        unsigned int txr_remaining = interface->num_tx_queues;
        unsigned int rxr_idx = 0, txr_idx = 0, v_idx = 0;
        int err;

        if (q_vectors >= (rxr_remaining + txr_remaining)) {
                for (; rxr_remaining; v_idx++) {
                        err = fm10k_alloc_q_vector(interface, 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 = fm10k_alloc_q_vector(interface, 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:
        fm10k_reset_num_queues(interface);

        while (v_idx--)
                fm10k_free_q_vector(interface, v_idx);

        return -ENOMEM;
}

/**
 * fm10k_free_q_vectors - Free memory allocated for interrupt vectors
 * @interface: 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 fm10k_free_q_vectors(struct fm10k_intfc *interface)
{
        int v_idx = interface->num_q_vectors;

        fm10k_reset_num_queues(interface);

        while (v_idx--)
                fm10k_free_q_vector(interface, v_idx);
}

/**
 * f10k_reset_msix_capability - reset MSI-X capability
 * @interface: board private structure to initialize
 *
 * Reset the MSI-X capability back to its starting state
 **/
static void fm10k_reset_msix_capability(struct fm10k_intfc *interface)
{
        pci_disable_msix(interface->pdev);
        kfree(interface->msix_entries);
        interface->msix_entries = NULL;
}

/**
 * f10k_init_msix_capability - configure MSI-X capability
 * @interface: board private structure to initialize
 *
 * Attempt to configure the interrupts using the best available
 * capabilities of the hardware and the kernel.
 **/
static int fm10k_init_msix_capability(struct fm10k_intfc *interface)
{
        struct fm10k_hw *hw = &interface->hw;
        int v_budget, vector;

        /* It's easy to be greedy for MSI-X vectors, but it really
         * doesn't do us much good if we have a lot more vectors
         * than CPU's.  So let's be conservative and only ask for
         * (roughly) the same number of vectors as there are CPU's.
         * the default is to use pairs of vectors
         */
        v_budget = max(interface->num_rx_queues, interface->num_tx_queues);
        v_budget = min_t(u16, v_budget, num_online_cpus());

        /* account for vectors not related to queues */
        v_budget += NON_Q_VECTORS(hw);

        /* At the same time, hardware can only support a maximum of
         * hw.mac->max_msix_vectors vectors.  With features
         * such as RSS and VMDq, we can easily surpass the number of Rx and Tx
         * descriptor queues supported by our device.  Thus, we cap it off in
         * those rare cases where the cpu count also exceeds our vector limit.
         */
        v_budget = min_t(int, v_budget, hw->mac.max_msix_vectors);

        /* A failure in MSI-X entry allocation is fatal. */
        interface->msix_entries = kcalloc(v_budget, sizeof(struct msix_entry),
                                          GFP_KERNEL);
        if (!interface->msix_entries)
                return -ENOMEM;

        /* populate entry values */
        for (vector = 0; vector < v_budget; vector++)
                interface->msix_entries[vector].entry = vector;

        /* Attempt to enable MSI-X with requested value */
        v_budget = pci_enable_msix_range(interface->pdev,
                                         interface->msix_entries,
                                         MIN_MSIX_COUNT(hw),
                                         v_budget);
        if (v_budget < 0) {
                kfree(interface->msix_entries);
                interface->msix_entries = NULL;
                return v_budget;
        }

        /* record the number of queues available for q_vectors */
        interface->num_q_vectors = v_budget - NON_Q_VECTORS(hw);

        return 0;
}

/**
 * fm10k_cache_ring_qos - Descriptor ring to register mapping for QoS
 * @interface: Interface structure continaining rings and devices
 *
 * Cache the descriptor ring offsets for Qos
 **/
static bool fm10k_cache_ring_qos(struct fm10k_intfc *interface)
{
        struct net_device *dev = interface->netdev;
        int pc, offset, rss_i, i, q_idx;
        u16 pc_stride = interface->ring_feature[RING_F_QOS].mask + 1;
        u8 num_pcs = netdev_get_num_tc(dev);

        if (num_pcs <= 1)
                return false;

        rss_i = interface->ring_feature[RING_F_RSS].indices;

        for (pc = 0, offset = 0; pc < num_pcs; pc++, offset += rss_i) {
                q_idx = pc;
                for (i = 0; i < rss_i; i++) {
                        interface->tx_ring[offset + i]->reg_idx = q_idx;
                        interface->tx_ring[offset + i]->qos_pc = pc;
                        interface->rx_ring[offset + i]->reg_idx = q_idx;
                        interface->rx_ring[offset + i]->qos_pc = pc;
                        q_idx += pc_stride;
                }
        }

        return true;
}

/**
 * fm10k_cache_ring_rss - Descriptor ring to register mapping for RSS
 * @interface: Interface structure continaining rings and devices
 *
 * Cache the descriptor ring offsets for RSS
 **/
static void fm10k_cache_ring_rss(struct fm10k_intfc *interface)
{
        int i;

        for (i = 0; i < interface->num_rx_queues; i++)
                interface->rx_ring[i]->reg_idx = i;

        for (i = 0; i < interface->num_tx_queues; i++)
                interface->tx_ring[i]->reg_idx = i;
}

/**
 * fm10k_assign_rings - Map rings to network devices
 * @interface: Interface structure containing rings and devices
 *
 * This function is meant to go though and configure both the network
 * devices so that they contain rings, and configure the rings so that
 * they function with their network devices.
 **/
static void fm10k_assign_rings(struct fm10k_intfc *interface)
{
        if (fm10k_cache_ring_qos(interface))
                return;

        fm10k_cache_ring_rss(interface);
}

static void fm10k_init_reta(struct fm10k_intfc *interface)
{
        u16 i, rss_i = interface->ring_feature[RING_F_RSS].indices;
        u32 reta;

        /* If the Rx flow indirection table has been configured manually, we
         * need to maintain it when possible.
         */
        if (netif_is_rxfh_configured(interface->netdev)) {
                for (i = FM10K_RETA_SIZE; i--;) {
                        reta = interface->reta[i];
                        if ((((reta << 24) >> 24) < rss_i) &&
                            (((reta << 16) >> 24) < rss_i) &&
                            (((reta <<  8) >> 24) < rss_i) &&
                            (((reta)       >> 24) < rss_i))
                                continue;

                        /* this should never happen */
                        dev_err(&interface->pdev->dev,
                                "RSS indirection table assigned flows out of queue bounds. Reconfiguring.\n");
                        goto repopulate_reta;
                }

                /* do nothing if all of the elements are in bounds */
                return;
        }

repopulate_reta:
        fm10k_write_reta(interface, NULL);
}

/**
 * fm10k_init_queueing_scheme - Determine proper queueing scheme
 * @interface: board private structure to initialize
 *
 * We determine which queueing scheme to use based on...
 * - Hardware queue count (num_*_queues)
 *   - defined by miscellaneous hardware support/features (RSS, etc.)
 **/
int fm10k_init_queueing_scheme(struct fm10k_intfc *interface)
{
        int err;

        /* Number of supported queues */
        fm10k_set_num_queues(interface);

        /* Configure MSI-X capability */
        err = fm10k_init_msix_capability(interface);
        if (err) {
                dev_err(&interface->pdev->dev,
                        "Unable to initialize MSI-X capability\n");
                goto err_init_msix;
        }

        /* Allocate memory for queues */
        err = fm10k_alloc_q_vectors(interface);
        if (err) {
                dev_err(&interface->pdev->dev,
                        "Unable to allocate queue vectors\n");
                goto err_alloc_q_vectors;
        }

        /* Map rings to devices, and map devices to physical queues */
        fm10k_assign_rings(interface);

        /* Initialize RSS redirection table */
        fm10k_init_reta(interface);

        return 0;

err_alloc_q_vectors:
        fm10k_reset_msix_capability(interface);
err_init_msix:
        fm10k_reset_num_queues(interface);
        return err;
}

/**
 * fm10k_clear_queueing_scheme - Clear the current queueing scheme settings
 * @interface: board private structure to clear queueing scheme on
 *
 * We go through and clear queueing specific resources and reset the structure
 * to pre-load conditions
 **/
void fm10k_clear_queueing_scheme(struct fm10k_intfc *interface)
{
        fm10k_free_q_vectors(interface);
        fm10k_reset_msix_capability(interface);
}