[deliverable/linux.git] / drivers / net / ethernet / intel / fm10k / fm10k_main.c

/* Intel Ethernet Switch Host Interface Driver
 * Copyright(c) 2013 - 2014 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 * Contact Information:
 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 */

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

MODULE_AUTHOR("Intel Corporation, <linux.nics@intel.com>");
MODULE_DESCRIPTION("Intel(R) Ethernet Switch Host Interface Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

/**
 * 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);

        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();
}
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 = alloc_page(GFP_ATOMIC | __GFP_COLD);
        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);
                bi->page = NULL;

                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 hdr_addr for the next_to_use descriptor */
                rx_desc->q.hdr_addr = 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 */
        memcpy(new_buff, old_buff, sizeof(struct fm10k_rx_buffer));

        /* 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 bool fm10k_can_reuse_rx_page(struct fm10k_rx_buffer *rx_buffer,
                                    struct page *page,
                                    unsigned int truesize)
{
        /* avoid re-using remote pages */
        if (unlikely(page_to_nid(page) != numa_mem_id()))
                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;

        /* since we are the only owner of the page and we need to
         * increment it, just set the value to 2 in order to avoid
         * an unnecessary locked operation
         */
        atomic_set(&page->_count, 2);
#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;

        /* bump ref count on page before it is given to the stack */
        get_page(page);
#endif

        return true;
}

/**
 * fm10k_add_rx_frag - Add contents of Rx buffer to sk_buff
 * @rx_ring: rx descriptor ring to transact packets on
 * @rx_buffer: buffer containing page to add
 * @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_ring *rx_ring,
                              struct fm10k_rx_buffer *rx_buffer,
                              union fm10k_rx_desc *rx_desc,
                              struct sk_buff *skb)
{
        struct page *page = rx_buffer->page;
        unsigned int size = le16_to_cpu(rx_desc->w.length);
#if (PAGE_SIZE < 8192)
        unsigned int truesize = FM10K_RX_BUFSZ;
#else
        unsigned int truesize = ALIGN(size, L1_CACHE_BYTES);
#endif

        if ((size <= FM10K_RX_HDR_LEN) && !skb_is_nonlinear(skb)) {
                unsigned char *va = page_address(page) + rx_buffer->page_offset;

                memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));

                /* we can reuse buffer as-is, just make sure it is local */
                if (likely(page_to_nid(page) == numa_mem_id()))
                        return true;

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

        skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
                        rx_buffer->page_offset, 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)
{
        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 = netdev_alloc_skb_ip_align(rx_ring->netdev,
                                                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,
                                      FM10K_RX_BUFSZ,
                                      DMA_FROM_DEVICE);

        /* pull page into skb */
        if (fm10k_add_rx_frag(rx_ring, rx_buffer, 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;
}

/**
 * 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_CB(skb)->fi.w.vlan = rx_desc->w.vlan;

        skb_record_rx_queue(skb, rx_ring->queue_index);

        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 != rx_ring->vid)
                        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vid);
        }

        skb->protocol = eth_type_trans(skb, rx_ring->netdev);

        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_pull_tail - fm10k specific version of skb_pull_tail
 * @rx_ring: rx descriptor ring packet is being transacted on
 * @rx_desc: pointer to the EOP Rx descriptor
 * @skb: pointer to current skb being adjusted
 *
 * This function is an fm10k specific version of __pskb_pull_tail.  The
 * main difference between this version and the original function is that
 * this function can make several assumptions about the state of things
 * that allow for significant optimizations versus the standard function.
 * As a result we can do things like drop a frag and maintain an accurate
 * truesize for the skb.
 */
static void fm10k_pull_tail(struct fm10k_ring *rx_ring,
                            union fm10k_rx_desc *rx_desc,
                            struct sk_buff *skb)
{
        struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
        unsigned char *va;
        unsigned int pull_len;

        /* it is valid to use page_address instead of kmap since we are
         * working with pages allocated out of the lomem pool per
         * alloc_page(GFP_ATOMIC)
         */
        va = skb_frag_address(frag);

        /* 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 */
        skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));

        /* update all of the pointers */
        skb_frag_size_sub(frag, pull_len);
        frag->page_offset += pull_len;
        skb->data_len -= pull_len;
        skb->tail += pull_len;
}

/**
 * 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)))) {
                dev_kfree_skb_any(skb);
                rx_ring->rx_stats.errors++;
                return true;
        }

        /* place header in linear portion of buffer */
        if (skb_is_nonlinear(skb))
                fm10k_pull_tail(rx_ring, rx_desc, skb);

        /* if skb_pad returns an error the skb was freed */
        if (unlikely(skb->len < 60)) {
                int pad_len = 60 - skb->len;

                if (skb_pad(skb, pad_len))
                        return true;
                __skb_put(skb, pad_len);
        }

        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 bool 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);

        do {
                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 (!fm10k_test_staterr(rx_desc, FM10K_RXD_STATUS_DD))
                        break;

                /* This memory barrier is needed to keep us from reading
                 * any other fields out of the rx_desc until we know the
                 * RXD_STATUS_DD bit is set
                 */
                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++;
        } while (likely(total_packets < budget));

        /* 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 < budget;
}

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 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;
        u16 i = tx_ring->next_to_use;
        u8 flags = 0;

        tx_desc = FM10K_TX_DESC(tx_ring, i);

        /* add HW VLAN tag */
        if (vlan_tx_tag_present(skb))
                tx_desc->vlan = cpu_to_le16(vlan_tx_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;

        /* notify HW of packet */
        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;
}

static int __fm10k_maybe_stop_tx(struct fm10k_ring *tx_ring, u16 size)
{
        netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);

        smp_mb();

        /* We need to 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);
}

netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb,
                                  struct fm10k_ring *tx_ring)
{
        struct fm10k_tx_buffer *first;
        u32 tx_flags = 0;
#if PAGE_SIZE > FM10K_MAX_DATA_PER_TXD
        unsigned short f;
#endif
        u16 count = TXD_USE_COUNT(skb_headlen(skb));

        /* 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
         */
#if PAGE_SIZE > FM10K_MAX_DATA_PER_TXD
        for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
                count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size);
#else
        count += skb_shinfo(skb)->nr_frags;
#endif
        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;

        fm10k_tx_map(tx_ring, first);

        fm10k_maybe_stop_tx(tx_ring, DESC_NEEDED);

        return NETDEV_TX_OK;
}

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

static u64 fm10k_get_tx_pending(struct fm10k_ring *ring)
{
        /* use SW head and tail until we have real hardware */
        u32 head = ring->next_to_clean;
        u32 tail = ring->next_to_use;

        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);

        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)) {
                netdev_err(interface->netdev, "Reset interface\n");
                interface->tx_timeout_count++;
                interface->flags |= FM10K_FLAG_RESET_REQUESTED;
                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
 **/
static bool fm10k_clean_tx_irq(struct fm10k_q_vector *q_vector,
                               struct fm10k_ring *tx_ring)
{
        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 */
                read_barrier_depends();

                /* 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 */
                dev_consume_skb_any(tx_buffer->skb);

                /* 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;

        /* Only update ITR if we are using adaptive setting */
        if (!(ring_container->itr & FM10K_ITR_ADAPTIVE))
                goto clear_counts;

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

        avg_wire_size = ring_container->total_bytes / packets;

        /* Add 24 bytes to size to account for CRC, preamble, and gap */
        avg_wire_size += 24;

        /* Don't starve jumbo frames */
        if (avg_wire_size > 3000)
                avg_wire_size = 3000;

        /* Give a little boost to mid-size frames */
        if ((avg_wire_size > 300) && (avg_wire_size < 1200))
                avg_wire_size /= 3;
        else
                avg_wire_size /= 2;

        /* 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;
        bool clean_complete = true;

        fm10k_for_each_ring(ring, q_vector->tx)
                clean_complete &= fm10k_clean_tx_irq(q_vector, ring);

        /* 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)
                clean_complete &= fm10k_clean_rx_irq(q_vector, ring,
                                                     per_ring_budget);

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

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

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

        return 0;
}

/**
 * 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)
{
        /* Start with base case */
        interface->num_rx_queues = 1;
        interface->num_tx_queues = 1;
}

/**
 * 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.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.count = rxr_count;

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

                /* 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++;
        }

        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_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:
        interface->num_tx_queues = 0;
        interface->num_rx_queues = 0;
        interface->num_q_vectors = 0;

        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;

        interface->num_tx_queues = 0;
        interface->num_rx_queues = 0;
        interface->num_q_vectors = 0;

        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 -ENOMEM;
        }

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

        return 0;
}

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

        /* If the netdev is initialized we have to maintain table if possible */
        if (interface->netdev->reg_state) {
                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;
                        goto repopulate_reta;
                }

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

repopulate_reta:
        /* Populate the redirection table 4 entries at a time.  To do this
         * we are generating the results for n and n+2 and then interleaving
         * those with the results with n+1 and n+3.
         */
        for (i = FM10K_RETA_SIZE; i--;) {
                /* first pass generates n and n+2 */
                base = ((i * 0x00040004) + 0x00020000) * rss_i;
                reta = (base & 0x3F803F80) >> 7;

                /* second pass generates n+1 and n+3 */
                base += 0x00010001 * rss_i;
                reta |= (base & 0x3F803F80) << 1;

                interface->reta[i] = reta;
        }
}

/**
 * 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");
                return err;
        }

        /* Allocate memory for queues */
        err = fm10k_alloc_q_vectors(interface);
        if (err)
                return err;

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

        return 0;
}

/**
 * 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);
}