// SPDX-License-Identifier: GPL-2.0
/*
 * Networking over Thunderbolt cable using Apple ThunderboltIP protocol
 *
 * Copyright (C) 2017, Intel Corporation
 * Authors: Amir Levy <amir.jer.levy@intel.com>
 *          Michael Jamet <michael.jamet@intel.com>
 *          Mika Westerberg <mika.westerberg@linux.intel.com>
 */

#include <linux/atomic.h>
#include <linux/highmem.h>
#include <linux/if_vlan.h>
#include <linux/jhash.h>
#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/sizes.h>
#include <linux/thunderbolt.h>
#include <linux/uuid.h>
#include <linux/workqueue.h>

#include <net/ip6_checksum.h>

/* Protocol timeouts in ms */
#define TBNET_LOGIN_DELAY       4500
#define TBNET_LOGIN_TIMEOUT     500
#define TBNET_LOGOUT_TIMEOUT    100

#define TBNET_RING_SIZE         256
#define TBNET_LOCAL_PATH        0xf
#define TBNET_LOGIN_RETRIES     60
#define TBNET_LOGOUT_RETRIES    5
#define TBNET_MATCH_FRAGS_ID    BIT(1)
#define TBNET_MAX_MTU           SZ_64K
#define TBNET_FRAME_SIZE        SZ_4K
#define TBNET_MAX_PAYLOAD_SIZE  \
        (TBNET_FRAME_SIZE - sizeof(struct thunderbolt_ip_frame_header))
/* Rx packets need to hold space for skb_shared_info */
#define TBNET_RX_MAX_SIZE       \
        (TBNET_FRAME_SIZE + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
#define TBNET_RX_PAGE_ORDER     get_order(TBNET_RX_MAX_SIZE)
#define TBNET_RX_PAGE_SIZE      (PAGE_SIZE << TBNET_RX_PAGE_ORDER)

#define TBNET_L0_PORT_NUM(route) ((route) & GENMASK(5, 0))

/**
 * struct thunderbolt_ip_frame_header - Header for each Thunderbolt frame
 * @frame_size: size of the data with the frame
 * @frame_index: running index on the frames
 * @frame_id: ID of the frame to match frames to specific packet
 * @frame_count: how many frames assembles a full packet
 *
 * Each data frame passed to the high-speed DMA ring has this header. If
 * the XDomain network directory announces that %TBNET_MATCH_FRAGS_ID is
 * supported then @frame_id is filled, otherwise it stays %0.
 */
struct thunderbolt_ip_frame_header {
        u32 frame_size;
        u16 frame_index;
        u16 frame_id;
        u32 frame_count;
};

enum thunderbolt_ip_frame_pdf {
        TBIP_PDF_FRAME_START = 1,
        TBIP_PDF_FRAME_END,
};

enum thunderbolt_ip_type {
        TBIP_LOGIN,
        TBIP_LOGIN_RESPONSE,
        TBIP_LOGOUT,
        TBIP_STATUS,
};

struct thunderbolt_ip_header {
        u32 route_hi;
        u32 route_lo;
        u32 length_sn;
        uuid_t uuid;
        uuid_t initiator_uuid;
        uuid_t target_uuid;
        u32 type;
        u32 command_id;
};

#define TBIP_HDR_LENGTH_MASK            GENMASK(5, 0)
#define TBIP_HDR_SN_MASK                GENMASK(28, 27)
#define TBIP_HDR_SN_SHIFT               27

struct thunderbolt_ip_login {
        struct thunderbolt_ip_header hdr;
        u32 proto_version;
        u32 transmit_path;
        u32 reserved[4];
};

#define TBIP_LOGIN_PROTO_VERSION        1

struct thunderbolt_ip_login_response {
        struct thunderbolt_ip_header hdr;
        u32 status;
        u32 receiver_mac[2];
        u32 receiver_mac_len;
        u32 reserved[4];
};

struct thunderbolt_ip_logout {
        struct thunderbolt_ip_header hdr;
};

struct thunderbolt_ip_status {
        struct thunderbolt_ip_header hdr;
        u32 status;
};

struct tbnet_stats {
        u64 tx_packets;
        u64 rx_packets;
        u64 tx_bytes;
        u64 rx_bytes;
        u64 rx_errors;
        u64 tx_errors;
        u64 rx_length_errors;
        u64 rx_over_errors;
        u64 rx_crc_errors;
        u64 rx_missed_errors;
};

struct tbnet_frame {
        struct net_device *dev;
        struct page *page;
        struct ring_frame frame;
};

struct tbnet_ring {
        struct tbnet_frame frames[TBNET_RING_SIZE];
        unsigned int cons;
        unsigned int prod;
        struct tb_ring *ring;
};

/**
 * struct tbnet - ThunderboltIP network driver private data
 * @svc: XDomain service the driver is bound to
 * @xd: XDomain the service blongs to
 * @handler: ThunderboltIP configuration protocol handler
 * @dev: Networking device
 * @napi: NAPI structure for Rx polling
 * @stats: Network statistics
 * @skb: Network packet that is currently processed on Rx path
 * @command_id: ID used for next configuration protocol packet
 * @login_sent: ThunderboltIP login message successfully sent
 * @login_received: ThunderboltIP login message received from the remote
 *                  host
 * @transmit_path: HopID the other end needs to use building the
 *                 opposite side path.
 * @connection_lock: Lock serializing access to @login_sent,
 *                   @login_received and @transmit_path.
 * @login_retries: Number of login retries currently done
 * @login_work: Worker to send ThunderboltIP login packets
 * @connected_work: Worker that finalizes the ThunderboltIP connection
 *                  setup and enables DMA paths for high speed data
 *                  transfers
 * @disconnect_work: Worker that handles tearing down the ThunderboltIP
 *                   connection
 * @rx_hdr: Copy of the currently processed Rx frame. Used when a
 *          network packet consists of multiple Thunderbolt frames.
 *          In host byte order.
 * @rx_ring: Software ring holding Rx frames
 * @frame_id: Frame ID use for next Tx packet
 *            (if %TBNET_MATCH_FRAGS_ID is supported in both ends)
 * @tx_ring: Software ring holding Tx frames
 */
struct tbnet {
        const struct tb_service *svc;
        struct tb_xdomain *xd;
        struct tb_protocol_handler handler;
        struct net_device *dev;
        struct napi_struct napi;
        struct tbnet_stats stats;
        struct sk_buff *skb;
        atomic_t command_id;
        bool login_sent;
        bool login_received;
        u32 transmit_path;
        struct mutex connection_lock;
        int login_retries;
        struct delayed_work login_work;
        struct work_struct connected_work;
        struct work_struct disconnect_work;
        struct thunderbolt_ip_frame_header rx_hdr;
        struct tbnet_ring rx_ring;
        atomic_t frame_id;
        struct tbnet_ring tx_ring;
};

/* Network property directory UUID: c66189ca-1cce-4195-bdb8-49592e5f5a4f */
static const uuid_t tbnet_dir_uuid =
        UUID_INIT(0xc66189ca, 0x1cce, 0x4195,
                  0xbd, 0xb8, 0x49, 0x59, 0x2e, 0x5f, 0x5a, 0x4f);

/* ThunderboltIP protocol UUID: 798f589e-3616-8a47-97c6-5664a920c8dd */
static const uuid_t tbnet_svc_uuid =
        UUID_INIT(0x798f589e, 0x3616, 0x8a47,
                  0x97, 0xc6, 0x56, 0x64, 0xa9, 0x20, 0xc8, 0xdd);

static struct tb_property_dir *tbnet_dir;

static void tbnet_fill_header(struct thunderbolt_ip_header *hdr, u64 route,
        u8 sequence, const uuid_t *initiator_uuid, const uuid_t *target_uuid,
        enum thunderbolt_ip_type type, size_t size, u32 command_id)
{
        u32 length_sn;

        /* Length does not include route_hi/lo and length_sn fields */
        length_sn = (size - 3 * 4) / 4;
        length_sn |= (sequence << TBIP_HDR_SN_SHIFT) & TBIP_HDR_SN_MASK;

        hdr->route_hi = upper_32_bits(route);
        hdr->route_lo = lower_32_bits(route);
        hdr->length_sn = length_sn;
        uuid_copy(&hdr->uuid, &tbnet_svc_uuid);
        uuid_copy(&hdr->initiator_uuid, initiator_uuid);
        uuid_copy(&hdr->target_uuid, target_uuid);
        hdr->type = type;
        hdr->command_id = command_id;
}

static int tbnet_login_response(struct tbnet *net, u64 route, u8 sequence,
                                u32 command_id)
{
        struct thunderbolt_ip_login_response reply;
        struct tb_xdomain *xd = net->xd;

        memset(&reply, 0, sizeof(reply));
        tbnet_fill_header(&reply.hdr, route, sequence, xd->local_uuid,
                          xd->remote_uuid, TBIP_LOGIN_RESPONSE, sizeof(reply),
                          command_id);
        memcpy(reply.receiver_mac, net->dev->dev_addr, ETH_ALEN);
        reply.receiver_mac_len = ETH_ALEN;

        return tb_xdomain_response(xd, &reply, sizeof(reply),
                                   TB_CFG_PKG_XDOMAIN_RESP);
}

static int tbnet_login_request(struct tbnet *net, u8 sequence)
{
        struct thunderbolt_ip_login_response reply;
        struct thunderbolt_ip_login request;
        struct tb_xdomain *xd = net->xd;

        memset(&request, 0, sizeof(request));
        tbnet_fill_header(&request.hdr, xd->route, sequence, xd->local_uuid,
                          xd->remote_uuid, TBIP_LOGIN, sizeof(request),
                          atomic_inc_return(&net->command_id));

        request.proto_version = TBIP_LOGIN_PROTO_VERSION;
        request.transmit_path = TBNET_LOCAL_PATH;

        return tb_xdomain_request(xd, &request, sizeof(request),
                                  TB_CFG_PKG_XDOMAIN_RESP, &reply,
                                  sizeof(reply), TB_CFG_PKG_XDOMAIN_RESP,
                                  TBNET_LOGIN_TIMEOUT);
}

static int tbnet_logout_response(struct tbnet *net, u64 route, u8 sequence,
                                 u32 command_id)
{
        struct thunderbolt_ip_status reply;
        struct tb_xdomain *xd = net->xd;

        memset(&reply, 0, sizeof(reply));
        tbnet_fill_header(&reply.hdr, route, sequence, xd->local_uuid,
                          xd->remote_uuid, TBIP_STATUS, sizeof(reply),
                          atomic_inc_return(&net->command_id));
        return tb_xdomain_response(xd, &reply, sizeof(reply),
                                   TB_CFG_PKG_XDOMAIN_RESP);
}

static int tbnet_logout_request(struct tbnet *net)
{
        struct thunderbolt_ip_logout request;
        struct thunderbolt_ip_status reply;
        struct tb_xdomain *xd = net->xd;

        memset(&request, 0, sizeof(request));
        tbnet_fill_header(&request.hdr, xd->route, 0, xd->local_uuid,
                          xd->remote_uuid, TBIP_LOGOUT, sizeof(request),
                          atomic_inc_return(&net->command_id));

        return tb_xdomain_request(xd, &request, sizeof(request),
                                  TB_CFG_PKG_XDOMAIN_RESP, &reply,
                                  sizeof(reply), TB_CFG_PKG_XDOMAIN_RESP,
                                  TBNET_LOGOUT_TIMEOUT);
}

static void start_login(struct tbnet *net)
{
        mutex_lock(&net->connection_lock);
        net->login_sent = false;
        net->login_received = false;
        mutex_unlock(&net->connection_lock);

        queue_delayed_work(system_long_wq, &net->login_work,
                           msecs_to_jiffies(1000));
}

static void stop_login(struct tbnet *net)
{
        cancel_delayed_work_sync(&net->login_work);
        cancel_work_sync(&net->connected_work);
}

static inline unsigned int tbnet_frame_size(const struct tbnet_frame *tf)
{
        return tf->frame.size ? : TBNET_FRAME_SIZE;
}

static void tbnet_free_buffers(struct tbnet_ring *ring)
{
        unsigned int i;

        for (i = 0; i < TBNET_RING_SIZE; i++) {
                struct device *dma_dev = tb_ring_dma_device(ring->ring);
                struct tbnet_frame *tf = &ring->frames[i];
                enum dma_data_direction dir;
                unsigned int order;
                size_t size;

                if (!tf->page)
                        continue;

                if (ring->ring->is_tx) {
                        dir = DMA_TO_DEVICE;
                        order = 0;
                        size = TBNET_FRAME_SIZE;
                } else {
                        dir = DMA_FROM_DEVICE;
                        order = TBNET_RX_PAGE_ORDER;
                        size = TBNET_RX_PAGE_SIZE;
                }

                if (tf->frame.buffer_phy)
                        dma_unmap_page(dma_dev, tf->frame.buffer_phy, size,
                                       dir);

                __free_pages(tf->page, order);
                tf->page = NULL;
        }

        ring->cons = 0;
        ring->prod = 0;
}

static void tbnet_tear_down(struct tbnet *net, bool send_logout)
{
        netif_carrier_off(net->dev);
        netif_stop_queue(net->dev);

        stop_login(net);

        mutex_lock(&net->connection_lock);

        if (net->login_sent && net->login_received) {
                int retries = TBNET_LOGOUT_RETRIES;

                while (send_logout && retries-- > 0) {
                        int ret = tbnet_logout_request(net);
                        if (ret != -ETIMEDOUT)
                                break;
                }

                tb_ring_stop(net->rx_ring.ring);
                tb_ring_stop(net->tx_ring.ring);
                tbnet_free_buffers(&net->rx_ring);
                tbnet_free_buffers(&net->tx_ring);

                if (tb_xdomain_disable_paths(net->xd))
                        netdev_warn(net->dev, "failed to disable DMA paths\n");
        }

        net->login_retries = 0;
        net->login_sent = false;
        net->login_received = false;

        mutex_unlock(&net->connection_lock);
}

static int tbnet_handle_packet(const void *buf, size_t size, void *data)
{
        const struct thunderbolt_ip_login *pkg = buf;
        struct tbnet *net = data;
        u32 command_id;
        int ret = 0;
        u32 sequence;
        u64 route;

        /* Make sure the packet is for us */
        if (size < sizeof(struct thunderbolt_ip_header))
                return 0;
        if (!uuid_equal(&pkg->hdr.initiator_uuid, net->xd->remote_uuid))
                return 0;
        if (!uuid_equal(&pkg->hdr.target_uuid, net->xd->local_uuid))
                return 0;

        route = ((u64)pkg->hdr.route_hi << 32) | pkg->hdr.route_lo;
        route &= ~BIT_ULL(63);
        if (route != net->xd->route)
                return 0;

        sequence = pkg->hdr.length_sn & TBIP_HDR_SN_MASK;
        sequence >>= TBIP_HDR_SN_SHIFT;
        command_id = pkg->hdr.command_id;

        switch (pkg->hdr.type) {
        case TBIP_LOGIN:
                if (!netif_running(net->dev))
                        break;

                ret = tbnet_login_response(net, route, sequence,
                                           pkg->hdr.command_id);
                if (!ret) {
                        mutex_lock(&net->connection_lock);
                        net->login_received = true;
                        net->transmit_path = pkg->transmit_path;

                        /* If we reached the number of max retries or
                         * previous logout, schedule another round of
                         * login retries
                         */
                        if (net->login_retries >= TBNET_LOGIN_RETRIES ||
                            !net->login_sent) {
                                net->login_retries = 0;
                                queue_delayed_work(system_long_wq,
                                                   &net->login_work, 0);
                        }
                        mutex_unlock(&net->connection_lock);

                        queue_work(system_long_wq, &net->connected_work);
                }
                break;

        case TBIP_LOGOUT:
                ret = tbnet_logout_response(net, route, sequence, command_id);
                if (!ret)
                        queue_work(system_long_wq, &net->disconnect_work);
                break;

        default:
                return 0;
        }

        if (ret)
                netdev_warn(net->dev, "failed to send ThunderboltIP response\n");

        return 1;
}

static unsigned int tbnet_available_buffers(const struct tbnet_ring *ring)
{
        return ring->prod - ring->cons;
}

static int tbnet_alloc_rx_buffers(struct tbnet *net, unsigned int nbuffers)
{
        struct tbnet_ring *ring = &net->rx_ring;
        int ret;

        while (nbuffers--) {
                struct device *dma_dev = tb_ring_dma_device(ring->ring);
                unsigned int index = ring->prod & (TBNET_RING_SIZE - 1);
                struct tbnet_frame *tf = &ring->frames[index];
                dma_addr_t dma_addr;

                if (tf->page)
                        break;

                /* Allocate page (order > 0) so that it can hold maximum
                 * ThunderboltIP frame (4kB) and the additional room for
                 * SKB shared info required by build_skb().
                 */
                tf->page = dev_alloc_pages(TBNET_RX_PAGE_ORDER);
                if (!tf->page) {
                        ret = -ENOMEM;
                        goto err_free;
                }

                dma_addr = dma_map_page(dma_dev, tf->page, 0,
                                        TBNET_RX_PAGE_SIZE, DMA_FROM_DEVICE);
                if (dma_mapping_error(dma_dev, dma_addr)) {
                        ret = -ENOMEM;
                        goto err_free;
                }

                tf->frame.buffer_phy = dma_addr;
                tf->dev = net->dev;

                tb_ring_rx(ring->ring, &tf->frame);

                ring->prod++;
        }

        return 0;

err_free:
        tbnet_free_buffers(ring);
        return ret;
}

static struct tbnet_frame *tbnet_get_tx_buffer(struct tbnet *net)
{
        struct tbnet_ring *ring = &net->tx_ring;
        struct device *dma_dev = tb_ring_dma_device(ring->ring);
        struct tbnet_frame *tf;
        unsigned int index;

        if (!tbnet_available_buffers(ring))
                return NULL;

        index = ring->cons++ & (TBNET_RING_SIZE - 1);

        tf = &ring->frames[index];
        tf->frame.size = 0;

        dma_sync_single_for_cpu(dma_dev, tf->frame.buffer_phy,
                                tbnet_frame_size(tf), DMA_TO_DEVICE);

        return tf;
}

static void tbnet_tx_callback(struct tb_ring *ring, struct ring_frame *frame,
                              bool canceled)
{
        struct tbnet_frame *tf = container_of(frame, typeof(*tf), frame);
        struct tbnet *net = netdev_priv(tf->dev);

        /* Return buffer to the ring */
        net->tx_ring.prod++;

        if (tbnet_available_buffers(&net->tx_ring) >= TBNET_RING_SIZE / 2)
                netif_wake_queue(net->dev);
}

static int tbnet_alloc_tx_buffers(struct tbnet *net)
{
        struct tbnet_ring *ring = &net->tx_ring;
        struct device *dma_dev = tb_ring_dma_device(ring->ring);
        unsigned int i;

        for (i = 0; i < TBNET_RING_SIZE; i++) {
                struct tbnet_frame *tf = &ring->frames[i];
                dma_addr_t dma_addr;

                tf->page = alloc_page(GFP_KERNEL);
                if (!tf->page) {
                        tbnet_free_buffers(ring);
                        return -ENOMEM;
                }

                dma_addr = dma_map_page(dma_dev, tf->page, 0, TBNET_FRAME_SIZE,
                                        DMA_TO_DEVICE);
                if (dma_mapping_error(dma_dev, dma_addr)) {
                        __free_page(tf->page);
                        tf->page = NULL;
                        tbnet_free_buffers(ring);
                        return -ENOMEM;
                }

                tf->dev = net->dev;
                tf->frame.buffer_phy = dma_addr;
                tf->frame.callback = tbnet_tx_callback;
                tf->frame.sof = TBIP_PDF_FRAME_START;
                tf->frame.eof = TBIP_PDF_FRAME_END;
        }

        ring->cons = 0;
        ring->prod = TBNET_RING_SIZE - 1;

        return 0;
}

static void tbnet_connected_work(struct work_struct *work)
{
        struct tbnet *net = container_of(work, typeof(*net), connected_work);
        bool connected;
        int ret;

        if (netif_carrier_ok(net->dev))
                return;

        mutex_lock(&net->connection_lock);
        connected = net->login_sent && net->login_received;
        mutex_unlock(&net->connection_lock);

        if (!connected)
                return;

        /* Both logins successful so enable the high-speed DMA paths and
         * start the network device queue.
         */
        ret = tb_xdomain_enable_paths(net->xd, TBNET_LOCAL_PATH,
                                      net->rx_ring.ring->hop,
                                      net->transmit_path,
                                      net->tx_ring.ring->hop);
        if (ret) {
                netdev_err(net->dev, "failed to enable DMA paths\n");
                return;
        }

        tb_ring_start(net->tx_ring.ring);
        tb_ring_start(net->rx_ring.ring);

        ret = tbnet_alloc_rx_buffers(net, TBNET_RING_SIZE);
        if (ret)
                goto err_stop_rings;

        ret = tbnet_alloc_tx_buffers(net);
        if (ret)
                goto err_free_rx_buffers;

        netif_carrier_on(net->dev);
        netif_start_queue(net->dev);
        return;

err_free_rx_buffers:
        tbnet_free_buffers(&net->rx_ring);
err_stop_rings:
        tb_ring_stop(net->rx_ring.ring);
        tb_ring_stop(net->tx_ring.ring);
}

static void tbnet_login_work(struct work_struct *work)
{
        struct tbnet *net = container_of(work, typeof(*net), login_work.work);
        unsigned long delay = msecs_to_jiffies(TBNET_LOGIN_DELAY);
        int ret;

        if (netif_carrier_ok(net->dev))
                return;

        ret = tbnet_login_request(net, net->login_retries % 4);
        if (ret) {
                if (net->login_retries++ < TBNET_LOGIN_RETRIES) {
                        queue_delayed_work(system_long_wq, &net->login_work,
                                           delay);
                } else {
                        netdev_info(net->dev, "ThunderboltIP login timed out\n");
                }
        } else {
                net->login_retries = 0;

                mutex_lock(&net->connection_lock);
                net->login_sent = true;
                mutex_unlock(&net->connection_lock);

                queue_work(system_long_wq, &net->connected_work);
        }
}

static void tbnet_disconnect_work(struct work_struct *work)
{
        struct tbnet *net = container_of(work, typeof(*net), disconnect_work);

        tbnet_tear_down(net, false);
}

static bool tbnet_check_frame(struct tbnet *net, const struct tbnet_frame *tf,
                              const struct thunderbolt_ip_frame_header *hdr)
{
        u32 frame_id, frame_count, frame_size, frame_index;
        unsigned int size;

        if (tf->frame.flags & RING_DESC_CRC_ERROR) {
                net->stats.rx_crc_errors++;
                return false;
        } else if (tf->frame.flags & RING_DESC_BUFFER_OVERRUN) {
                net->stats.rx_over_errors++;
                return false;
        }

        /* Should be greater than just header i.e. contains data */
        size = tbnet_frame_size(tf);
        if (size <= sizeof(*hdr)) {
                net->stats.rx_length_errors++;
                return false;
        }

        frame_count = le32_to_cpu(hdr->frame_count);
        frame_size = le32_to_cpu(hdr->frame_size);
        frame_index = le16_to_cpu(hdr->frame_index);
        frame_id = le16_to_cpu(hdr->frame_id);

        if ((frame_size > size - sizeof(*hdr)) || !frame_size) {
                net->stats.rx_length_errors++;
                return false;
        }

        /* In case we're in the middle of packet, validate the frame
         * header based on first fragment of the packet.
         */
        if (net->skb && net->rx_hdr.frame_count) {
                /* Check the frame count fits the count field */
                if (frame_count != net->rx_hdr.frame_count) {
                        net->stats.rx_length_errors++;
                        return false;
                }

                /* Check the frame identifiers are incremented correctly,
                 * and id is matching.
                 */
                if (frame_index != net->rx_hdr.frame_index + 1 ||
                    frame_id != net->rx_hdr.frame_id) {
                        net->stats.rx_missed_errors++;
                        return false;
                }

                if (net->skb->len + frame_size > TBNET_MAX_MTU) {
                        net->stats.rx_length_errors++;
                        return false;
                }

                return true;
        }

        /* Start of packet, validate the frame header */
        if (frame_count == 0 || frame_count > TBNET_RING_SIZE / 4) {
                net->stats.rx_length_errors++;
                return false;
        }
        if (frame_index != 0) {
                net->stats.rx_missed_errors++;
                return false;
        }

        return true;
}

static int tbnet_poll(struct napi_struct *napi, int budget)
{
        struct tbnet *net = container_of(napi, struct tbnet, napi);
        unsigned int cleaned_count = tbnet_available_buffers(&net->rx_ring);
        struct device *dma_dev = tb_ring_dma_device(net->rx_ring.ring);
        unsigned int rx_packets = 0;

        while (rx_packets < budget) {
                const struct thunderbolt_ip_frame_header *hdr;
                unsigned int hdr_size = sizeof(*hdr);
                struct sk_buff *skb = NULL;
                struct ring_frame *frame;
                struct tbnet_frame *tf;
                struct page *page;
                bool last = true;
                u32 frame_size;

                /* Return some buffers to hardware, one at a time is too
                 * slow so allocate MAX_SKB_FRAGS buffers at the same
                 * time.
                 */
                if (cleaned_count >= MAX_SKB_FRAGS) {
                        tbnet_alloc_rx_buffers(net, cleaned_count);
                        cleaned_count = 0;
                }

                frame = tb_ring_poll(net->rx_ring.ring);
                if (!frame)
                        break;

                dma_unmap_page(dma_dev, frame->buffer_phy,
                               TBNET_RX_PAGE_SIZE, DMA_FROM_DEVICE);

                tf = container_of(frame, typeof(*tf), frame);

                page = tf->page;
                tf->page = NULL;
                net->rx_ring.cons++;
                cleaned_count++;

                hdr = page_address(page);
                if (!tbnet_check_frame(net, tf, hdr)) {
                        __free_pages(page, TBNET_RX_PAGE_ORDER);
                        dev_kfree_skb_any(net->skb);
                        net->skb = NULL;
                        continue;
                }

                frame_size = le32_to_cpu(hdr->frame_size);

                skb = net->skb;
                if (!skb) {
                        skb = build_skb(page_address(page),
                                        TBNET_RX_PAGE_SIZE);
                        if (!skb) {
                                __free_pages(page, TBNET_RX_PAGE_ORDER);
                                net->stats.rx_errors++;
                                break;
                        }

                        skb_reserve(skb, hdr_size);
                        skb_put(skb, frame_size);

                        net->skb = skb;
                } else {
                        skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
                                        page, hdr_size, frame_size,
                                        TBNET_RX_PAGE_SIZE - hdr_size);
                }

                net->rx_hdr.frame_size = frame_size;
                net->rx_hdr.frame_count = le32_to_cpu(hdr->frame_count);
                net->rx_hdr.frame_index = le16_to_cpu(hdr->frame_index);
                net->rx_hdr.frame_id = le16_to_cpu(hdr->frame_id);
                last = net->rx_hdr.frame_index == net->rx_hdr.frame_count - 1;

                rx_packets++;
                net->stats.rx_bytes += frame_size;

                if (last) {
                        skb->protocol = eth_type_trans(skb, net->dev);
                        napi_gro_receive(&net->napi, skb);
                        net->skb = NULL;
                }
        }

        net->stats.rx_packets += rx_packets;

        if (cleaned_count)
                tbnet_alloc_rx_buffers(net, cleaned_count);

        if (rx_packets >= budget)
                return budget;

        napi_complete_done(napi, rx_packets);
        /* Re-enable the ring interrupt */
        tb_ring_poll_complete(net->rx_ring.ring);

        return rx_packets;
}

static void tbnet_start_poll(void *data)
{
        struct tbnet *net = data;

        napi_schedule(&net->napi);
}

static int tbnet_open(struct net_device *dev)
{
        struct tbnet *net = netdev_priv(dev);
        struct tb_xdomain *xd = net->xd;
        u16 sof_mask, eof_mask;
        struct tb_ring *ring;

        netif_carrier_off(dev);

        ring = tb_ring_alloc_tx(xd->tb->nhi, -1, TBNET_RING_SIZE,
                                RING_FLAG_FRAME);
        if (!ring) {
                netdev_err(dev, "failed to allocate Tx ring\n");
                return -ENOMEM;
        }
        net->tx_ring.ring = ring;

        sof_mask = BIT(TBIP_PDF_FRAME_START);
        eof_mask = BIT(TBIP_PDF_FRAME_END);

        ring = tb_ring_alloc_rx(xd->tb->nhi, -1, TBNET_RING_SIZE,
                                RING_FLAG_FRAME | RING_FLAG_E2E, sof_mask,
                                eof_mask, tbnet_start_poll, net);
        if (!ring) {
                netdev_err(dev, "failed to allocate Rx ring\n");
                tb_ring_free(net->tx_ring.ring);
                net->tx_ring.ring = NULL;
                return -ENOMEM;
        }
        net->rx_ring.ring = ring;

        napi_enable(&net->napi);
        start_login(net);

        return 0;
}

static int tbnet_stop(struct net_device *dev)
{
        struct tbnet *net = netdev_priv(dev);

        napi_disable(&net->napi);

        cancel_work_sync(&net->disconnect_work);
        tbnet_tear_down(net, true);

        tb_ring_free(net->rx_ring.ring);
        net->rx_ring.ring = NULL;
        tb_ring_free(net->tx_ring.ring);
        net->tx_ring.ring = NULL;

        return 0;
}

static bool tbnet_xmit_csum_and_map(struct tbnet *net, struct sk_buff *skb,
        struct tbnet_frame **frames, u32 frame_count)
{
        struct thunderbolt_ip_frame_header *hdr = page_address(frames[0]->page);
        struct device *dma_dev = tb_ring_dma_device(net->tx_ring.ring);
        __wsum wsum = htonl(skb->len - skb_transport_offset(skb));
        unsigned int i, len, offset = skb_transport_offset(skb);
        __be16 protocol = skb->protocol;
        void *data = skb->data;
        void *dest = hdr + 1;
        __sum16 *tucso;

        if (skb->ip_summed != CHECKSUM_PARTIAL) {
                /* No need to calculate checksum so we just update the
                 * total frame count and sync the frames for DMA.
                 */
                for (i = 0; i < frame_count; i++) {
                        hdr = page_address(frames[i]->page);
                        hdr->frame_count = cpu_to_le32(frame_count);
                        dma_sync_single_for_device(dma_dev,
                                frames[i]->frame.buffer_phy,
                                tbnet_frame_size(frames[i]), DMA_TO_DEVICE);
                }

                return true;
        }

        if (protocol == htons(ETH_P_8021Q)) {
                struct vlan_hdr *vhdr, vh;

                vhdr = skb_header_pointer(skb, ETH_HLEN, sizeof(vh), &vh);
                if (!vhdr)
                        return false;

                protocol = vhdr->h_vlan_encapsulated_proto;
        }

        /* Data points on the beginning of packet.
         * Check is the checksum absolute place in the packet.
         * ipcso will update IP checksum.
         * tucso will update TCP/UPD checksum.
         */
        if (protocol == htons(ETH_P_IP)) {
                __sum16 *ipcso = dest + ((void *)&(ip_hdr(skb)->check) - data);

                *ipcso = 0;
                *ipcso = ip_fast_csum(dest + skb_network_offset(skb),
                                      ip_hdr(skb)->ihl);

                if (ip_hdr(skb)->protocol == IPPROTO_TCP)
                        tucso = dest + ((void *)&(tcp_hdr(skb)->check) - data);
                else if (ip_hdr(skb)->protocol == IPPROTO_UDP)
                        tucso = dest + ((void *)&(udp_hdr(skb)->check) - data);
                else
                        return false;

                *tucso = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
                                            ip_hdr(skb)->daddr, 0,
                                            ip_hdr(skb)->protocol, 0);
        } else if (skb_is_gso_v6(skb)) {
                tucso = dest + ((void *)&(tcp_hdr(skb)->check) - data);
                *tucso = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                          &ipv6_hdr(skb)->daddr, 0,
                                          IPPROTO_TCP, 0);
                return false;
        } else if (protocol == htons(ETH_P_IPV6)) {
                tucso = dest + skb_checksum_start_offset(skb) + skb->csum_offset;
                *tucso = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                          &ipv6_hdr(skb)->daddr, 0,
                                          ipv6_hdr(skb)->nexthdr, 0);
        } else {
                return false;
        }

        /* First frame was headers, rest of the frames contain data.
         * Calculate checksum over each frame.
         */
        for (i = 0; i < frame_count; i++) {
                hdr = page_address(frames[i]->page);
                dest = (void *)(hdr + 1) + offset;
                len = le32_to_cpu(hdr->frame_size) - offset;
                wsum = csum_partial(dest, len, wsum);
                hdr->frame_count = cpu_to_le32(frame_count);

                offset = 0;
        }

        *tucso = csum_fold(wsum);

        /* Checksum is finally calculated and we don't touch the memory
         * anymore, so DMA sync the frames now.
         */
        for (i = 0; i < frame_count; i++) {
                dma_sync_single_for_device(dma_dev, frames[i]->frame.buffer_phy,
                        tbnet_frame_size(frames[i]), DMA_TO_DEVICE);
        }

        return true;
}

static void *tbnet_kmap_frag(struct sk_buff *skb, unsigned int frag_num,
                             unsigned int *len)
{
        const skb_frag_t *frag = &skb_shinfo(skb)->frags[frag_num];

        *len = skb_frag_size(frag);
        return kmap_atomic(skb_frag_page(frag)) + frag->page_offset;
}

static netdev_tx_t tbnet_start_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
{
        struct tbnet *net = netdev_priv(dev);
        struct tbnet_frame *frames[MAX_SKB_FRAGS];
        u16 frame_id = atomic_read(&net->frame_id);
        struct thunderbolt_ip_frame_header *hdr;
        unsigned int len = skb_headlen(skb);
        unsigned int data_len = skb->len;
        unsigned int nframes, i;
        unsigned int frag = 0;
        void *src = skb->data;
        u32 frame_index = 0;
        bool unmap = false;
        void *dest;

        nframes = DIV_ROUND_UP(data_len, TBNET_MAX_PAYLOAD_SIZE);
        if (tbnet_available_buffers(&net->tx_ring) < nframes) {
                netif_stop_queue(net->dev);
                return NETDEV_TX_BUSY;
        }

        frames[frame_index] = tbnet_get_tx_buffer(net);
        if (!frames[frame_index])
                goto err_drop;

        hdr = page_address(frames[frame_index]->page);
        dest = hdr + 1;

        /* If overall packet is bigger than the frame data size */
        while (data_len > TBNET_MAX_PAYLOAD_SIZE) {
                unsigned int size_left = TBNET_MAX_PAYLOAD_SIZE;

                hdr->frame_size = cpu_to_le32(TBNET_MAX_PAYLOAD_SIZE);
                hdr->frame_index = cpu_to_le16(frame_index);
                hdr->frame_id = cpu_to_le16(frame_id);

                do {
                        if (len > size_left) {
                                /* Copy data onto Tx buffer data with
                                 * full frame size then break and go to
                                 * next frame
                                 */
                                memcpy(dest, src, size_left);
                                len -= size_left;
                                dest += size_left;
                                src += size_left;
                                break;
                        }

                        memcpy(dest, src, len);
                        size_left -= len;
                        dest += len;

                        if (unmap) {
                                kunmap_atomic(src);
                                unmap = false;
                        }

                        /* Ensure all fragments have been processed */
                        if (frag < skb_shinfo(skb)->nr_frags) {
                                /* Map and then unmap quickly */
                                src = tbnet_kmap_frag(skb, frag++, &len);
                                unmap = true;
                        } else if (unlikely(size_left > 0)) {
                                goto err_drop;
                        }
                } while (size_left > 0);

                data_len -= TBNET_MAX_PAYLOAD_SIZE;
                frame_index++;

                frames[frame_index] = tbnet_get_tx_buffer(net);
                if (!frames[frame_index])
                        goto err_drop;

                hdr = page_address(frames[frame_index]->page);
                dest = hdr + 1;
        }

        hdr->frame_size = cpu_to_le32(data_len);
        hdr->frame_index = cpu_to_le16(frame_index);
        hdr->frame_id = cpu_to_le16(frame_id);

        frames[frame_index]->frame.size = data_len + sizeof(*hdr);

        /* In case the remaining data_len is smaller than a frame */
        while (len < data_len) {
                memcpy(dest, src, len);
                data_len -= len;
                dest += len;

                if (unmap) {
                        kunmap_atomic(src);
                        unmap = false;
                }

                if (frag < skb_shinfo(skb)->nr_frags) {
                        src = tbnet_kmap_frag(skb, frag++, &len);
                        unmap = true;
                } else if (unlikely(data_len > 0)) {
                        goto err_drop;
                }
        }

        memcpy(dest, src, data_len);

        if (unmap)
                kunmap_atomic(src);

        if (!tbnet_xmit_csum_and_map(net, skb, frames, frame_index + 1))
                goto err_drop;

        for (i = 0; i < frame_index + 1; i++)
                tb_ring_tx(net->tx_ring.ring, &frames[i]->frame);

        if (net->svc->prtcstns & TBNET_MATCH_FRAGS_ID)
                atomic_inc(&net->frame_id);

        net->stats.tx_packets++;
        net->stats.tx_bytes += skb->len;

        dev_consume_skb_any(skb);

        return NETDEV_TX_OK;

err_drop:
        /* We can re-use the buffers */
        net->tx_ring.cons -= frame_index;

        dev_kfree_skb_any(skb);
        net->stats.tx_errors++;

        return NETDEV_TX_OK;
}

static void tbnet_get_stats64(struct net_device *dev,
                              struct rtnl_link_stats64 *stats)
{
        struct tbnet *net = netdev_priv(dev);

        stats->tx_packets = net->stats.tx_packets;
        stats->rx_packets = net->stats.rx_packets;
        stats->tx_bytes = net->stats.tx_bytes;
        stats->rx_bytes = net->stats.rx_bytes;
        stats->rx_errors = net->stats.rx_errors + net->stats.rx_length_errors +
                net->stats.rx_over_errors + net->stats.rx_crc_errors +
                net->stats.rx_missed_errors;
        stats->tx_errors = net->stats.tx_errors;
        stats->rx_length_errors = net->stats.rx_length_errors;
        stats->rx_over_errors = net->stats.rx_over_errors;
        stats->rx_crc_errors = net->stats.rx_crc_errors;
        stats->rx_missed_errors = net->stats.rx_missed_errors;
}

static const struct net_device_ops tbnet_netdev_ops = {
        .ndo_open = tbnet_open,
        .ndo_stop = tbnet_stop,
        .ndo_start_xmit = tbnet_start_xmit,
        .ndo_get_stats64 = tbnet_get_stats64,
};

static void tbnet_generate_mac(struct net_device *dev)
{
        const struct tbnet *net = netdev_priv(dev);
        const struct tb_xdomain *xd = net->xd;
        u8 phy_port;
        u32 hash;

        phy_port = tb_phy_port_from_link(TBNET_L0_PORT_NUM(xd->route));

        /* Unicast and locally administered MAC */
        dev->dev_addr[0] = phy_port << 4 | 0x02;
        hash = jhash2((u32 *)xd->local_uuid, 4, 0);
        memcpy(dev->dev_addr + 1, &hash, sizeof(hash));
        hash = jhash2((u32 *)xd->local_uuid, 4, hash);
        dev->dev_addr[5] = hash & 0xff;
}

static int tbnet_probe(struct tb_service *svc, const struct tb_service_id *id)
{
        struct tb_xdomain *xd = tb_service_parent(svc);
        struct net_device *dev;
        struct tbnet *net;
        int ret;

        dev = alloc_etherdev(sizeof(*net));
        if (!dev)
                return -ENOMEM;

        SET_NETDEV_DEV(dev, &svc->dev);

        net = netdev_priv(dev);
        INIT_DELAYED_WORK(&net->login_work, tbnet_login_work);
        INIT_WORK(&net->connected_work, tbnet_connected_work);
        INIT_WORK(&net->disconnect_work, tbnet_disconnect_work);
        mutex_init(&net->connection_lock);
        atomic_set(&net->command_id, 0);
        atomic_set(&net->frame_id, 0);
        net->svc = svc;
        net->dev = dev;
        net->xd = xd;

        tbnet_generate_mac(dev);

        strcpy(dev->name, "thunderbolt%d");
        dev->netdev_ops = &tbnet_netdev_ops;

        /* ThunderboltIP takes advantage of TSO packets but instead of
         * segmenting them we just split the packet into Thunderbolt
         * frames (maximum payload size of each frame is 4084 bytes) and
         * calculate checksum over the whole packet here.
         *
         * The receiving side does the opposite if the host OS supports
         * LRO, otherwise it needs to split the large packet into MTU
         * sized smaller packets.
         *
         * In order to receive large packets from the networking stack,
         * we need to announce support for most of the offloading
         * features here.
         */
        dev->hw_features = NETIF_F_SG | NETIF_F_ALL_TSO | NETIF_F_GRO |
                           NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
        dev->features = dev->hw_features | NETIF_F_HIGHDMA;
        dev->hard_header_len += sizeof(struct thunderbolt_ip_frame_header);

        netif_napi_add(dev, &net->napi, tbnet_poll, NAPI_POLL_WEIGHT);

        /* MTU range: 68 - 65522 */
        dev->min_mtu = ETH_MIN_MTU;
        dev->max_mtu = TBNET_MAX_MTU - ETH_HLEN;

        net->handler.uuid = &tbnet_svc_uuid;
        net->handler.callback = tbnet_handle_packet,
        net->handler.data = net;
        tb_register_protocol_handler(&net->handler);

        tb_service_set_drvdata(svc, net);

        ret = register_netdev(dev);
        if (ret) {
                tb_unregister_protocol_handler(&net->handler);
                free_netdev(dev);
                return ret;
        }

        return 0;
}

static void tbnet_remove(struct tb_service *svc)
{
        struct tbnet *net = tb_service_get_drvdata(svc);

        unregister_netdev(net->dev);
        tb_unregister_protocol_handler(&net->handler);
        free_netdev(net->dev);
}

static void tbnet_shutdown(struct tb_service *svc)
{
        tbnet_tear_down(tb_service_get_drvdata(svc), true);
}

static int __maybe_unused tbnet_suspend(struct device *dev)
{
        struct tb_service *svc = tb_to_service(dev);
        struct tbnet *net = tb_service_get_drvdata(svc);

        stop_login(net);
        if (netif_running(net->dev)) {
                netif_device_detach(net->dev);
                tbnet_tear_down(net, true);
        }

        tb_unregister_protocol_handler(&net->handler);
        return 0;
}

static int __maybe_unused tbnet_resume(struct device *dev)
{
        struct tb_service *svc = tb_to_service(dev);
        struct tbnet *net = tb_service_get_drvdata(svc);

        tb_register_protocol_handler(&net->handler);

        netif_carrier_off(net->dev);
        if (netif_running(net->dev)) {
                netif_device_attach(net->dev);
                start_login(net);
        }

        return 0;
}

static const struct dev_pm_ops tbnet_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(tbnet_suspend, tbnet_resume)
};

static const struct tb_service_id tbnet_ids[] = {
        { TB_SERVICE("network", 1) },
        { },
};
MODULE_DEVICE_TABLE(tbsvc, tbnet_ids);

static struct tb_service_driver tbnet_driver = {
        .driver = {
                .owner = THIS_MODULE,
                .name = "thunderbolt-net",
                .pm = &tbnet_pm_ops,
        },
        .probe = tbnet_probe,
        .remove = tbnet_remove,
        .shutdown = tbnet_shutdown,
        .id_table = tbnet_ids,
};

static int __init tbnet_init(void)
{
        int ret;

        tbnet_dir = tb_property_create_dir(&tbnet_dir_uuid);
        if (!tbnet_dir)
                return -ENOMEM;

        tb_property_add_immediate(tbnet_dir, "prtcid", 1);
        tb_property_add_immediate(tbnet_dir, "prtcvers", 1);
        tb_property_add_immediate(tbnet_dir, "prtcrevs", 1);
        tb_property_add_immediate(tbnet_dir, "prtcstns",
                                  TBNET_MATCH_FRAGS_ID);

        ret = tb_register_property_dir("network", tbnet_dir);
        if (ret) {
                tb_property_free_dir(tbnet_dir);
                return ret;
        }

        return tb_register_service_driver(&tbnet_driver);
}
module_init(tbnet_init);

static void __exit tbnet_exit(void)
{
        tb_unregister_service_driver(&tbnet_driver);
        tb_unregister_property_dir("network", tbnet_dir);
        tb_property_free_dir(tbnet_dir);
}
module_exit(tbnet_exit);

MODULE_AUTHOR("Amir Levy <amir.jer.levy@intel.com>");
MODULE_AUTHOR("Michael Jamet <michael.jamet@intel.com>");
MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
MODULE_DESCRIPTION("Thunderbolt network driver");
MODULE_LICENSE("GPL v2");