/****************************************************************************
 * Driver for Solarflare network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2013 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

#include <linux/pci.h>
#include <linux/tcp.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/ipv6.h>
#include <linux/slab.h>
#include <net/ipv6.h>
#include <linux/if_ether.h>
#include <linux/highmem.h>
#include <linux/cache.h>
#include "net_driver.h"
#include "efx.h"
#include "io.h"
#include "nic.h"
#include "tx.h"
#include "workarounds.h"

static inline u8 *ef4_tx_get_copy_buffer(struct ef4_tx_queue *tx_queue,
                                         struct ef4_tx_buffer *buffer)
{
        unsigned int index = ef4_tx_queue_get_insert_index(tx_queue);
        struct ef4_buffer *page_buf =
                &tx_queue->cb_page[index >> (PAGE_SHIFT - EF4_TX_CB_ORDER)];
        unsigned int offset =
                ((index << EF4_TX_CB_ORDER) + NET_IP_ALIGN) & (PAGE_SIZE - 1);

        if (unlikely(!page_buf->addr) &&
            ef4_nic_alloc_buffer(tx_queue->efx, page_buf, PAGE_SIZE,
                                 GFP_ATOMIC))
                return NULL;
        buffer->dma_addr = page_buf->dma_addr + offset;
        buffer->unmap_len = 0;
        return (u8 *)page_buf->addr + offset;
}

u8 *ef4_tx_get_copy_buffer_limited(struct ef4_tx_queue *tx_queue,
                                   struct ef4_tx_buffer *buffer, size_t len)
{
        if (len > EF4_TX_CB_SIZE)
                return NULL;
        return ef4_tx_get_copy_buffer(tx_queue, buffer);
}

static void ef4_dequeue_buffer(struct ef4_tx_queue *tx_queue,
                               struct ef4_tx_buffer *buffer,
                               unsigned int *pkts_compl,
                               unsigned int *bytes_compl)
{
        if (buffer->unmap_len) {
                struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
                dma_addr_t unmap_addr = buffer->dma_addr - buffer->dma_offset;
                if (buffer->flags & EF4_TX_BUF_MAP_SINGLE)
                        dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
                                         DMA_TO_DEVICE);
                else
                        dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
                                       DMA_TO_DEVICE);
                buffer->unmap_len = 0;
        }

        if (buffer->flags & EF4_TX_BUF_SKB) {
                (*pkts_compl)++;
                (*bytes_compl) += buffer->skb->len;
                dev_consume_skb_any((struct sk_buff *)buffer->skb);
                netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
                           "TX queue %d transmission id %x complete\n",
                           tx_queue->queue, tx_queue->read_count);
        }

        buffer->len = 0;
        buffer->flags = 0;
}

unsigned int ef4_tx_max_skb_descs(struct ef4_nic *efx)
{
        /* This is probably too much since we don't have any TSO support;
         * it's a left-over from when we had Software TSO.  But it's safer
         * to leave it as-is than try to determine a new bound.
         */
        /* Header and payload descriptor for each output segment, plus
         * one for every input fragment boundary within a segment
         */
        unsigned int max_descs = EF4_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;

        /* Possibly one more per segment for the alignment workaround,
         * or for option descriptors
         */
        if (EF4_WORKAROUND_5391(efx))
                max_descs += EF4_TSO_MAX_SEGS;

        /* Possibly more for PCIe page boundaries within input fragments */
        if (PAGE_SIZE > EF4_PAGE_SIZE)
                max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
                                   DIV_ROUND_UP(GSO_MAX_SIZE, EF4_PAGE_SIZE));

        return max_descs;
}

static void ef4_tx_maybe_stop_queue(struct ef4_tx_queue *txq1)
{
        /* We need to consider both queues that the net core sees as one */
        struct ef4_tx_queue *txq2 = ef4_tx_queue_partner(txq1);
        struct ef4_nic *efx = txq1->efx;
        unsigned int fill_level;

        fill_level = max(txq1->insert_count - txq1->old_read_count,
                         txq2->insert_count - txq2->old_read_count);
        if (likely(fill_level < efx->txq_stop_thresh))
                return;

        /* We used the stale old_read_count above, which gives us a
         * pessimistic estimate of the fill level (which may even
         * validly be >= efx->txq_entries).  Now try again using
         * read_count (more likely to be a cache miss).
         *
         * If we read read_count and then conditionally stop the
         * queue, it is possible for the completion path to race with
         * us and complete all outstanding descriptors in the middle,
         * after which there will be no more completions to wake it.
         * Therefore we stop the queue first, then read read_count
         * (with a memory barrier to ensure the ordering), then
         * restart the queue if the fill level turns out to be low
         * enough.
         */
        netif_tx_stop_queue(txq1->core_txq);
        smp_mb();
        txq1->old_read_count = ACCESS_ONCE(txq1->read_count);
        txq2->old_read_count = ACCESS_ONCE(txq2->read_count);

        fill_level = max(txq1->insert_count - txq1->old_read_count,
                         txq2->insert_count - txq2->old_read_count);
        EF4_BUG_ON_PARANOID(fill_level >= efx->txq_entries);
        if (likely(fill_level < efx->txq_stop_thresh)) {
                smp_mb();
                if (likely(!efx->loopback_selftest))
                        netif_tx_start_queue(txq1->core_txq);
        }
}

static int ef4_enqueue_skb_copy(struct ef4_tx_queue *tx_queue,
                                struct sk_buff *skb)
{
        unsigned int min_len = tx_queue->tx_min_size;
        unsigned int copy_len = skb->len;
        struct ef4_tx_buffer *buffer;
        u8 *copy_buffer;
        int rc;

        EF4_BUG_ON_PARANOID(copy_len > EF4_TX_CB_SIZE);

        buffer = ef4_tx_queue_get_insert_buffer(tx_queue);

        copy_buffer = ef4_tx_get_copy_buffer(tx_queue, buffer);
        if (unlikely(!copy_buffer))
                return -ENOMEM;

        rc = skb_copy_bits(skb, 0, copy_buffer, copy_len);
        EF4_WARN_ON_PARANOID(rc);
        if (unlikely(copy_len < min_len)) {
                memset(copy_buffer + copy_len, 0, min_len - copy_len);
                buffer->len = min_len;
        } else {
                buffer->len = copy_len;
        }

        buffer->skb = skb;
        buffer->flags = EF4_TX_BUF_SKB;

        ++tx_queue->insert_count;
        return rc;
}

static struct ef4_tx_buffer *ef4_tx_map_chunk(struct ef4_tx_queue *tx_queue,
                                              dma_addr_t dma_addr,
                                              size_t len)
{
        const struct ef4_nic_type *nic_type = tx_queue->efx->type;
        struct ef4_tx_buffer *buffer;
        unsigned int dma_len;

        /* Map the fragment taking account of NIC-dependent DMA limits. */
        do {
                buffer = ef4_tx_queue_get_insert_buffer(tx_queue);
                dma_len = nic_type->tx_limit_len(tx_queue, dma_addr, len);

                buffer->len = dma_len;
                buffer->dma_addr = dma_addr;
                buffer->flags = EF4_TX_BUF_CONT;
                len -= dma_len;
                dma_addr += dma_len;
                ++tx_queue->insert_count;
        } while (len);

        return buffer;
}

/* Map all data from an SKB for DMA and create descriptors on the queue.
 */
static int ef4_tx_map_data(struct ef4_tx_queue *tx_queue, struct sk_buff *skb)
{
        struct ef4_nic *efx = tx_queue->efx;
        struct device *dma_dev = &efx->pci_dev->dev;
        unsigned int frag_index, nr_frags;
        dma_addr_t dma_addr, unmap_addr;
        unsigned short dma_flags;
        size_t len, unmap_len;

        nr_frags = skb_shinfo(skb)->nr_frags;
        frag_index = 0;

        /* Map header data. */
        len = skb_headlen(skb);
        dma_addr = dma_map_single(dma_dev, skb->data, len, DMA_TO_DEVICE);
        dma_flags = EF4_TX_BUF_MAP_SINGLE;
        unmap_len = len;
        unmap_addr = dma_addr;

        if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
                return -EIO;

        /* Add descriptors for each fragment. */
        do {
                struct ef4_tx_buffer *buffer;
                skb_frag_t *fragment;

                buffer = ef4_tx_map_chunk(tx_queue, dma_addr, len);

                /* The final descriptor for a fragment is responsible for
                 * unmapping the whole fragment.
                 */
                buffer->flags = EF4_TX_BUF_CONT | dma_flags;
                buffer->unmap_len = unmap_len;
                buffer->dma_offset = buffer->dma_addr - unmap_addr;

                if (frag_index >= nr_frags) {
                        /* Store SKB details with the final buffer for
                         * the completion.
                         */
                        buffer->skb = skb;
                        buffer->flags = EF4_TX_BUF_SKB | dma_flags;
                        return 0;
                }

                /* Move on to the next fragment. */
                fragment = &skb_shinfo(skb)->frags[frag_index++];
                len = skb_frag_size(fragment);
                dma_addr = skb_frag_dma_map(dma_dev, fragment,
                                0, len, DMA_TO_DEVICE);
                dma_flags = 0;
                unmap_len = len;
                unmap_addr = dma_addr;

                if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
                        return -EIO;
        } while (1);
}

/* Remove buffers put into a tx_queue.  None of the buffers must have
 * an skb attached.
 */
static void ef4_enqueue_unwind(struct ef4_tx_queue *tx_queue)
{
        struct ef4_tx_buffer *buffer;

        /* Work backwards until we hit the original insert pointer value */
        while (tx_queue->insert_count != tx_queue->write_count) {
                --tx_queue->insert_count;
                buffer = __ef4_tx_queue_get_insert_buffer(tx_queue);
                ef4_dequeue_buffer(tx_queue, buffer, NULL, NULL);
        }
}

/*
 * Add a socket buffer to a TX queue
 *
 * This maps all fragments of a socket buffer for DMA and adds them to
 * the TX queue.  The queue's insert pointer will be incremented by
 * the number of fragments in the socket buffer.
 *
 * If any DMA mapping fails, any mapped fragments will be unmapped,
 * the queue's insert pointer will be restored to its original value.
 *
 * This function is split out from ef4_hard_start_xmit to allow the
 * loopback test to direct packets via specific TX queues.
 *
 * Returns NETDEV_TX_OK.
 * You must hold netif_tx_lock() to call this function.
 */
netdev_tx_t ef4_enqueue_skb(struct ef4_tx_queue *tx_queue, struct sk_buff *skb)
{
        bool data_mapped = false;
        unsigned int skb_len;

        skb_len = skb->len;
        EF4_WARN_ON_PARANOID(skb_is_gso(skb));

        if (skb_len < tx_queue->tx_min_size ||
                        (skb->data_len && skb_len <= EF4_TX_CB_SIZE)) {
                /* Pad short packets or coalesce short fragmented packets. */
                if (ef4_enqueue_skb_copy(tx_queue, skb))
                        goto err;
                tx_queue->cb_packets++;
                data_mapped = true;
        }

        /* Map for DMA and create descriptors if we haven't done so already. */
        if (!data_mapped && (ef4_tx_map_data(tx_queue, skb)))
                goto err;

        /* Update BQL */
        netdev_tx_sent_queue(tx_queue->core_txq, skb_len);

        /* Pass off to hardware */
        if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
                struct ef4_tx_queue *txq2 = ef4_tx_queue_partner(tx_queue);

                /* There could be packets left on the partner queue if those
                 * SKBs had skb->xmit_more set. If we do not push those they
                 * could be left for a long time and cause a netdev watchdog.
                 */
                if (txq2->xmit_more_available)
                        ef4_nic_push_buffers(txq2);

                ef4_nic_push_buffers(tx_queue);
        } else {
                tx_queue->xmit_more_available = skb->xmit_more;
        }

        tx_queue->tx_packets++;

        ef4_tx_maybe_stop_queue(tx_queue);

        return NETDEV_TX_OK;


err:
        ef4_enqueue_unwind(tx_queue);
        dev_kfree_skb_any(skb);
        return NETDEV_TX_OK;
}

/* Remove packets from the TX queue
 *
 * This removes packets from the TX queue, up to and including the
 * specified index.
 */
static void ef4_dequeue_buffers(struct ef4_tx_queue *tx_queue,
                                unsigned int index,
                                unsigned int *pkts_compl,
                                unsigned int *bytes_compl)
{
        struct ef4_nic *efx = tx_queue->efx;
        unsigned int stop_index, read_ptr;

        stop_index = (index + 1) & tx_queue->ptr_mask;
        read_ptr = tx_queue->read_count & tx_queue->ptr_mask;

        while (read_ptr != stop_index) {
                struct ef4_tx_buffer *buffer = &tx_queue->buffer[read_ptr];

                if (!(buffer->flags & EF4_TX_BUF_OPTION) &&
                    unlikely(buffer->len == 0)) {
                        netif_err(efx, tx_err, efx->net_dev,
                                  "TX queue %d spurious TX completion id %x\n",
                                  tx_queue->queue, read_ptr);
                        ef4_schedule_reset(efx, RESET_TYPE_TX_SKIP);
                        return;
                }

                ef4_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);

                ++tx_queue->read_count;
                read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
        }
}

/* Initiate a packet transmission.  We use one channel per CPU
 * (sharing when we have more CPUs than channels).  On Falcon, the TX
 * completion events will be directed back to the CPU that transmitted
 * the packet, which should be cache-efficient.
 *
 * Context: non-blocking.
 * Note that returning anything other than NETDEV_TX_OK will cause the
 * OS to free the skb.
 */
netdev_tx_t ef4_hard_start_xmit(struct sk_buff *skb,
                                struct net_device *net_dev)
{
        struct ef4_nic *efx = netdev_priv(net_dev);
        struct ef4_tx_queue *tx_queue;
        unsigned index, type;

        EF4_WARN_ON_PARANOID(!netif_device_present(net_dev));

        index = skb_get_queue_mapping(skb);
        type = skb->ip_summed == CHECKSUM_PARTIAL ? EF4_TXQ_TYPE_OFFLOAD : 0;
        if (index >= efx->n_tx_channels) {
                index -= efx->n_tx_channels;
                type |= EF4_TXQ_TYPE_HIGHPRI;
        }
        tx_queue = ef4_get_tx_queue(efx, index, type);

        return ef4_enqueue_skb(tx_queue, skb);
}

void ef4_init_tx_queue_core_txq(struct ef4_tx_queue *tx_queue)
{
        struct ef4_nic *efx = tx_queue->efx;

        /* Must be inverse of queue lookup in ef4_hard_start_xmit() */
        tx_queue->core_txq =
                netdev_get_tx_queue(efx->net_dev,
                                    tx_queue->queue / EF4_TXQ_TYPES +
                                    ((tx_queue->queue & EF4_TXQ_TYPE_HIGHPRI) ?
                                     efx->n_tx_channels : 0));
}

int ef4_setup_tc(struct net_device *net_dev, u32 handle, __be16 proto,
                 struct tc_to_netdev *ntc)
{
        struct ef4_nic *efx = netdev_priv(net_dev);
        struct ef4_channel *channel;
        struct ef4_tx_queue *tx_queue;
        unsigned tc, num_tc;
        int rc;

        if (ntc->type != TC_SETUP_MQPRIO)
                return -EINVAL;

        num_tc = ntc->tc;

        if (ef4_nic_rev(efx) < EF4_REV_FALCON_B0 || num_tc > EF4_MAX_TX_TC)
                return -EINVAL;

        if (num_tc == net_dev->num_tc)
                return 0;

        for (tc = 0; tc < num_tc; tc++) {
                net_dev->tc_to_txq[tc].offset = tc * efx->n_tx_channels;
                net_dev->tc_to_txq[tc].count = efx->n_tx_channels;
        }

        if (num_tc > net_dev->num_tc) {
                /* Initialise high-priority queues as necessary */
                ef4_for_each_channel(channel, efx) {
                        ef4_for_each_possible_channel_tx_queue(tx_queue,
                                                               channel) {
                                if (!(tx_queue->queue & EF4_TXQ_TYPE_HIGHPRI))
                                        continue;
                                if (!tx_queue->buffer) {
                                        rc = ef4_probe_tx_queue(tx_queue);
                                        if (rc)
                                                return rc;
                                }
                                if (!tx_queue->initialised)
                                        ef4_init_tx_queue(tx_queue);
                                ef4_init_tx_queue_core_txq(tx_queue);
                        }
                }
        } else {
                /* Reduce number of classes before number of queues */
                net_dev->num_tc = num_tc;
        }

        rc = netif_set_real_num_tx_queues(net_dev,
                                          max_t(int, num_tc, 1) *
                                          efx->n_tx_channels);
        if (rc)
                return rc;

        /* Do not destroy high-priority queues when they become
         * unused.  We would have to flush them first, and it is
         * fairly difficult to flush a subset of TX queues.  Leave
         * it to ef4_fini_channels().
         */

        net_dev->num_tc = num_tc;
        return 0;
}

void ef4_xmit_done(struct ef4_tx_queue *tx_queue, unsigned int index)
{
        unsigned fill_level;
        struct ef4_nic *efx = tx_queue->efx;
        struct ef4_tx_queue *txq2;
        unsigned int pkts_compl = 0, bytes_compl = 0;

        EF4_BUG_ON_PARANOID(index > tx_queue->ptr_mask);

        ef4_dequeue_buffers(tx_queue, index, &pkts_compl, &bytes_compl);
        tx_queue->pkts_compl += pkts_compl;
        tx_queue->bytes_compl += bytes_compl;

        if (pkts_compl > 1)
                ++tx_queue->merge_events;

        /* See if we need to restart the netif queue.  This memory
         * barrier ensures that we write read_count (inside
         * ef4_dequeue_buffers()) before reading the queue status.
         */
        smp_mb();
        if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
            likely(efx->port_enabled) &&
            likely(netif_device_present(efx->net_dev))) {
                txq2 = ef4_tx_queue_partner(tx_queue);
                fill_level = max(tx_queue->insert_count - tx_queue->read_count,
                                 txq2->insert_count - txq2->read_count);
                if (fill_level <= efx->txq_wake_thresh)
                        netif_tx_wake_queue(tx_queue->core_txq);
        }

        /* Check whether the hardware queue is now empty */
        if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
                tx_queue->old_write_count = ACCESS_ONCE(tx_queue->write_count);
                if (tx_queue->read_count == tx_queue->old_write_count) {
                        smp_mb();
                        tx_queue->empty_read_count =
                                tx_queue->read_count | EF4_EMPTY_COUNT_VALID;
                }
        }
}

static unsigned int ef4_tx_cb_page_count(struct ef4_tx_queue *tx_queue)
{
        return DIV_ROUND_UP(tx_queue->ptr_mask + 1, PAGE_SIZE >> EF4_TX_CB_ORDER);
}

int ef4_probe_tx_queue(struct ef4_tx_queue *tx_queue)
{
        struct ef4_nic *efx = tx_queue->efx;
        unsigned int entries;
        int rc;

        /* Create the smallest power-of-two aligned ring */
        entries = max(roundup_pow_of_two(efx->txq_entries), EF4_MIN_DMAQ_SIZE);
        EF4_BUG_ON_PARANOID(entries > EF4_MAX_DMAQ_SIZE);
        tx_queue->ptr_mask = entries - 1;

        netif_dbg(efx, probe, efx->net_dev,
                  "creating TX queue %d size %#x mask %#x\n",
                  tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask);

        /* Allocate software ring */
        tx_queue->buffer = kcalloc(entries, sizeof(*tx_queue->buffer),
                                   GFP_KERNEL);
        if (!tx_queue->buffer)
                return -ENOMEM;

        tx_queue->cb_page = kcalloc(ef4_tx_cb_page_count(tx_queue),
                                    sizeof(tx_queue->cb_page[0]), GFP_KERNEL);
        if (!tx_queue->cb_page) {
                rc = -ENOMEM;
                goto fail1;
        }

        /* Allocate hardware ring */
        rc = ef4_nic_probe_tx(tx_queue);
        if (rc)
                goto fail2;

        return 0;

fail2:
        kfree(tx_queue->cb_page);
        tx_queue->cb_page = NULL;
fail1:
        kfree(tx_queue->buffer);
        tx_queue->buffer = NULL;
        return rc;
}

void ef4_init_tx_queue(struct ef4_tx_queue *tx_queue)
{
        struct ef4_nic *efx = tx_queue->efx;

        netif_dbg(efx, drv, efx->net_dev,
                  "initialising TX queue %d\n", tx_queue->queue);

        tx_queue->insert_count = 0;
        tx_queue->write_count = 0;
        tx_queue->old_write_count = 0;
        tx_queue->read_count = 0;
        tx_queue->old_read_count = 0;
        tx_queue->empty_read_count = 0 | EF4_EMPTY_COUNT_VALID;
        tx_queue->xmit_more_available = false;

        /* Some older hardware requires Tx writes larger than 32. */
        tx_queue->tx_min_size = EF4_WORKAROUND_15592(efx) ? 33 : 0;

        /* Set up TX descriptor ring */
        ef4_nic_init_tx(tx_queue);

        tx_queue->initialised = true;
}

void ef4_fini_tx_queue(struct ef4_tx_queue *tx_queue)
{
        struct ef4_tx_buffer *buffer;

        netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
                  "shutting down TX queue %d\n", tx_queue->queue);

        if (!tx_queue->buffer)
                return;

        /* Free any buffers left in the ring */
        while (tx_queue->read_count != tx_queue->write_count) {
                unsigned int pkts_compl = 0, bytes_compl = 0;
                buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
                ef4_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);

                ++tx_queue->read_count;
        }
        tx_queue->xmit_more_available = false;
        netdev_tx_reset_queue(tx_queue->core_txq);
}

void ef4_remove_tx_queue(struct ef4_tx_queue *tx_queue)
{
        int i;

        if (!tx_queue->buffer)
                return;

        netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
                  "destroying TX queue %d\n", tx_queue->queue);
        ef4_nic_remove_tx(tx_queue);

        if (tx_queue->cb_page) {
                for (i = 0; i < ef4_tx_cb_page_count(tx_queue); i++)
                        ef4_nic_free_buffer(tx_queue->efx,
                                            &tx_queue->cb_page[i]);
                kfree(tx_queue->cb_page);
                tx_queue->cb_page = NULL;
        }

        kfree(tx_queue->buffer);
        tx_queue->buffer = NULL;
}