/*
 *  Shared Memory Communications over RDMA (SMC-R) and RoCE
 *
 *  IB infrastructure:
 *  Establish SMC-R as an Infiniband Client to be notified about added and
 *  removed IB devices of type RDMA.
 *  Determine device and port characteristics for these IB devices.
 *
 *  Copyright IBM Corp. 2016
 *
 *  Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
 */

#include <linux/random.h>
#include <linux/workqueue.h>
#include <rdma/ib_verbs.h>

#include "smc_pnet.h"
#include "smc_ib.h"
#include "smc_core.h"
#include "smc_wr.h"
#include "smc.h"

#define SMC_QP_MIN_RNR_TIMER            5
#define SMC_QP_TIMEOUT                  15 /* 4096 * 2 ** timeout usec */
#define SMC_QP_RETRY_CNT                        7 /* 7: infinite */
#define SMC_QP_RNR_RETRY                        7 /* 7: infinite */

struct smc_ib_devices smc_ib_devices = {        /* smc-registered ib devices */
        .lock = __SPIN_LOCK_UNLOCKED(smc_ib_devices.lock),
        .list = LIST_HEAD_INIT(smc_ib_devices.list),
};

#define SMC_LOCAL_SYSTEMID_RESET        "%%%%%%%"

u8 local_systemid[SMC_SYSTEMID_LEN] = SMC_LOCAL_SYSTEMID_RESET; /* unique system
                                                                 * identifier
                                                                 */

int smc_ib_get_memory_region(struct ib_pd *pd, int access_flags,
                             struct ib_mr **mr)
{
        int rc;

        if (*mr)
                return 0; /* already done */

        /* obtain unique key -
         * next invocation of get_dma_mr returns a different key!
         */
        *mr = pd->device->get_dma_mr(pd, access_flags);
        rc = PTR_ERR_OR_ZERO(*mr);
        if (IS_ERR(*mr))
                *mr = NULL;
        return rc;
}

static int smc_ib_modify_qp_init(struct smc_link *lnk)
{
        struct ib_qp_attr qp_attr;

        memset(&qp_attr, 0, sizeof(qp_attr));
        qp_attr.qp_state = IB_QPS_INIT;
        qp_attr.pkey_index = 0;
        qp_attr.port_num = lnk->ibport;
        qp_attr.qp_access_flags = IB_ACCESS_LOCAL_WRITE
                                | IB_ACCESS_REMOTE_WRITE;
        return ib_modify_qp(lnk->roce_qp, &qp_attr,
                            IB_QP_STATE | IB_QP_PKEY_INDEX |
                            IB_QP_ACCESS_FLAGS | IB_QP_PORT);
}

static int smc_ib_modify_qp_rtr(struct smc_link *lnk)
{
        enum ib_qp_attr_mask qp_attr_mask =
                IB_QP_STATE | IB_QP_AV | IB_QP_PATH_MTU | IB_QP_DEST_QPN |
                IB_QP_RQ_PSN | IB_QP_MAX_DEST_RD_ATOMIC | IB_QP_MIN_RNR_TIMER;
        struct ib_qp_attr qp_attr;

        memset(&qp_attr, 0, sizeof(qp_attr));
        qp_attr.qp_state = IB_QPS_RTR;
        qp_attr.path_mtu = min(lnk->path_mtu, lnk->peer_mtu);
        qp_attr.ah_attr.port_num = lnk->ibport;
        qp_attr.ah_attr.ah_flags = IB_AH_GRH;
        qp_attr.ah_attr.grh.hop_limit = 1;
        memcpy(&qp_attr.ah_attr.grh.dgid, lnk->peer_gid,
               sizeof(lnk->peer_gid));
        memcpy(&qp_attr.ah_attr.dmac, lnk->peer_mac,
               sizeof(lnk->peer_mac));
        qp_attr.dest_qp_num = lnk->peer_qpn;
        qp_attr.rq_psn = lnk->peer_psn; /* starting receive packet seq # */
        qp_attr.max_dest_rd_atomic = 1; /* max # of resources for incoming
                                         * requests
                                         */
        qp_attr.min_rnr_timer = SMC_QP_MIN_RNR_TIMER;

        return ib_modify_qp(lnk->roce_qp, &qp_attr, qp_attr_mask);
}

int smc_ib_modify_qp_rts(struct smc_link *lnk)
{
        struct ib_qp_attr qp_attr;

        memset(&qp_attr, 0, sizeof(qp_attr));
        qp_attr.qp_state = IB_QPS_RTS;
        qp_attr.timeout = SMC_QP_TIMEOUT;       /* local ack timeout */
        qp_attr.retry_cnt = SMC_QP_RETRY_CNT;   /* retry count */
        qp_attr.rnr_retry = SMC_QP_RNR_RETRY;   /* RNR retries, 7=infinite */
        qp_attr.sq_psn = lnk->psn_initial;      /* starting send packet seq # */
        qp_attr.max_rd_atomic = 1;      /* # of outstanding RDMA reads and
                                         * atomic ops allowed
                                         */
        return ib_modify_qp(lnk->roce_qp, &qp_attr,
                            IB_QP_STATE | IB_QP_TIMEOUT | IB_QP_RETRY_CNT |
                            IB_QP_SQ_PSN | IB_QP_RNR_RETRY |
                            IB_QP_MAX_QP_RD_ATOMIC);
}

int smc_ib_modify_qp_reset(struct smc_link *lnk)
{
        struct ib_qp_attr qp_attr;

        memset(&qp_attr, 0, sizeof(qp_attr));
        qp_attr.qp_state = IB_QPS_RESET;
        return ib_modify_qp(lnk->roce_qp, &qp_attr, IB_QP_STATE);
}

int smc_ib_ready_link(struct smc_link *lnk)
{
        struct smc_link_group *lgr =
                container_of(lnk, struct smc_link_group, lnk[0]);
        int rc = 0;

        rc = smc_ib_modify_qp_init(lnk);
        if (rc)
                goto out;

        rc = smc_ib_modify_qp_rtr(lnk);
        if (rc)
                goto out;
        smc_wr_remember_qp_attr(lnk);
        rc = ib_req_notify_cq(lnk->smcibdev->roce_cq_recv,
                              IB_CQ_SOLICITED_MASK);
        if (rc)
                goto out;
        rc = smc_wr_rx_post_init(lnk);
        if (rc)
                goto out;
        smc_wr_remember_qp_attr(lnk);

        if (lgr->role == SMC_SERV) {
                rc = smc_ib_modify_qp_rts(lnk);
                if (rc)
                        goto out;
                smc_wr_remember_qp_attr(lnk);
        }
out:
        return rc;
}

/* process context wrapper for might_sleep smc_ib_remember_port_attr */
static void smc_ib_port_event_work(struct work_struct *work)
{
        struct smc_ib_device *smcibdev = container_of(
                work, struct smc_ib_device, port_event_work);
        u8 port_idx;

        for_each_set_bit(port_idx, &smcibdev->port_event_mask, SMC_MAX_PORTS) {
                smc_ib_remember_port_attr(smcibdev, port_idx + 1);
                clear_bit(port_idx, &smcibdev->port_event_mask);
        }
}

/* can be called in IRQ context */
static void smc_ib_global_event_handler(struct ib_event_handler *handler,
                                        struct ib_event *ibevent)
{
        struct smc_ib_device *smcibdev;
        u8 port_idx;

        smcibdev = container_of(handler, struct smc_ib_device, event_handler);
        if (!smc_pnet_find_ib(smcibdev->ibdev->name))
                return;

        switch (ibevent->event) {
        case IB_EVENT_PORT_ERR:
                port_idx = ibevent->element.port_num - 1;
                set_bit(port_idx, &smcibdev->port_event_mask);
                schedule_work(&smcibdev->port_event_work);
                /* fall through */
        case IB_EVENT_DEVICE_FATAL:
                /* tbd in follow-on patch:
                 * abnormal close of corresponding connections
                 */
                break;
        case IB_EVENT_PORT_ACTIVE:
                port_idx = ibevent->element.port_num - 1;
                set_bit(port_idx, &smcibdev->port_event_mask);
                schedule_work(&smcibdev->port_event_work);
                break;
        default:
                break;
        }
}

void smc_ib_dealloc_protection_domain(struct smc_link *lnk)
{
        ib_dealloc_pd(lnk->roce_pd);
        lnk->roce_pd = NULL;
}

int smc_ib_create_protection_domain(struct smc_link *lnk)
{
        int rc;

        lnk->roce_pd = ib_alloc_pd(lnk->smcibdev->ibdev, 0);
        rc = PTR_ERR_OR_ZERO(lnk->roce_pd);
        if (IS_ERR(lnk->roce_pd))
                lnk->roce_pd = NULL;
        return rc;
}

static void smc_ib_qp_event_handler(struct ib_event *ibevent, void *priv)
{
        switch (ibevent->event) {
        case IB_EVENT_DEVICE_FATAL:
        case IB_EVENT_GID_CHANGE:
        case IB_EVENT_PORT_ERR:
        case IB_EVENT_QP_ACCESS_ERR:
                /* tbd in follow-on patch:
                 * abnormal close of corresponding connections
                 */
                break;
        default:
                break;
        }
}

void smc_ib_destroy_queue_pair(struct smc_link *lnk)
{
        ib_destroy_qp(lnk->roce_qp);
        lnk->roce_qp = NULL;
}

/* create a queue pair within the protection domain for a link */
int smc_ib_create_queue_pair(struct smc_link *lnk)
{
        struct ib_qp_init_attr qp_attr = {
                .event_handler = smc_ib_qp_event_handler,
                .qp_context = lnk,
                .send_cq = lnk->smcibdev->roce_cq_send,
                .recv_cq = lnk->smcibdev->roce_cq_recv,
                .srq = NULL,
                .cap = {
                        .max_send_wr = SMC_WR_BUF_CNT,
                                /* include unsolicited rdma_writes as well,
                                 * there are max. 2 RDMA_WRITE per 1 WR_SEND
                                 */
                        .max_recv_wr = SMC_WR_BUF_CNT * 3,
                        .max_send_sge = SMC_IB_MAX_SEND_SGE,
                        .max_recv_sge = 1,
                        .max_inline_data = SMC_WR_TX_SIZE,
                },
                .sq_sig_type = IB_SIGNAL_REQ_WR,
                .qp_type = IB_QPT_RC,
        };
        int rc;

        lnk->roce_qp = ib_create_qp(lnk->roce_pd, &qp_attr);
        rc = PTR_ERR_OR_ZERO(lnk->roce_qp);
        if (IS_ERR(lnk->roce_qp))
                lnk->roce_qp = NULL;
        else
                smc_wr_remember_qp_attr(lnk);
        return rc;
}

/* map a new TX or RX buffer to DMA */
int smc_ib_buf_map(struct smc_ib_device *smcibdev, int buf_size,
                   struct smc_buf_desc *buf_slot,
                   enum dma_data_direction data_direction)
{
        int rc = 0;

        if (buf_slot->dma_addr[SMC_SINGLE_LINK])
                return rc; /* already mapped */
        buf_slot->dma_addr[SMC_SINGLE_LINK] =
                ib_dma_map_single(smcibdev->ibdev, buf_slot->cpu_addr,
                                  buf_size, data_direction);
        if (ib_dma_mapping_error(smcibdev->ibdev,
                                 buf_slot->dma_addr[SMC_SINGLE_LINK]))
                rc = -EIO;
        return rc;
}

void smc_ib_buf_unmap(struct smc_ib_device *smcibdev, int buf_size,
                      struct smc_buf_desc *buf_slot,
                      enum dma_data_direction data_direction)
{
        if (!buf_slot->dma_addr[SMC_SINGLE_LINK])
                return; /* already unmapped */
        ib_dma_unmap_single(smcibdev->ibdev, *buf_slot->dma_addr, buf_size,
                            data_direction);
        buf_slot->dma_addr[SMC_SINGLE_LINK] = 0;
}

static int smc_ib_fill_gid_and_mac(struct smc_ib_device *smcibdev, u8 ibport)
{
        struct net_device *ndev;
        int rc;

        rc = ib_query_gid(smcibdev->ibdev, ibport, 0,
                          &smcibdev->gid[ibport - 1], NULL);
        /* the SMC protocol requires specification of the roce MAC address;
         * if net_device cannot be determined, it can be derived from gid 0
         */
        ndev = smcibdev->ibdev->get_netdev(smcibdev->ibdev, ibport);
        if (ndev) {
                memcpy(&smcibdev->mac, ndev->dev_addr, ETH_ALEN);
        } else if (!rc) {
                memcpy(&smcibdev->mac[ibport - 1][0],
                       &smcibdev->gid[ibport - 1].raw[8], 3);
                memcpy(&smcibdev->mac[ibport - 1][3],
                       &smcibdev->gid[ibport - 1].raw[13], 3);
                smcibdev->mac[ibport - 1][0] &= ~0x02;
        }
        return rc;
}

/* Create an identifier unique for this instance of SMC-R.
 * The MAC-address of the first active registered IB device
 * plus a random 2-byte number is used to create this identifier.
 * This name is delivered to the peer during connection initialization.
 */
static inline void smc_ib_define_local_systemid(struct smc_ib_device *smcibdev,
                                                u8 ibport)
{
        memcpy(&local_systemid[2], &smcibdev->mac[ibport - 1],
               sizeof(smcibdev->mac[ibport - 1]));
        get_random_bytes(&local_systemid[0], 2);
}

bool smc_ib_port_active(struct smc_ib_device *smcibdev, u8 ibport)
{
        return smcibdev->pattr[ibport - 1].state == IB_PORT_ACTIVE;
}

int smc_ib_remember_port_attr(struct smc_ib_device *smcibdev, u8 ibport)
{
        int rc;

        memset(&smcibdev->pattr[ibport - 1], 0,
               sizeof(smcibdev->pattr[ibport - 1]));
        rc = ib_query_port(smcibdev->ibdev, ibport,
                           &smcibdev->pattr[ibport - 1]);
        if (rc)
                goto out;
        rc = smc_ib_fill_gid_and_mac(smcibdev, ibport);
        if (rc)
                goto out;
        if (!strncmp(local_systemid, SMC_LOCAL_SYSTEMID_RESET,
                     sizeof(local_systemid)) &&
            smc_ib_port_active(smcibdev, ibport))
                /* create unique system identifier */
                smc_ib_define_local_systemid(smcibdev, ibport);
out:
        return rc;
}

long smc_ib_setup_per_ibdev(struct smc_ib_device *smcibdev)
{
        struct ib_cq_init_attr cqattr = {
                .cqe = SMC_WR_MAX_CQE, .comp_vector = 0 };
        long rc;

        smcibdev->roce_cq_send = ib_create_cq(smcibdev->ibdev,
                                              smc_wr_tx_cq_handler, NULL,
                                              smcibdev, &cqattr);
        rc = PTR_ERR_OR_ZERO(smcibdev->roce_cq_send);
        if (IS_ERR(smcibdev->roce_cq_send)) {
                smcibdev->roce_cq_send = NULL;
                return rc;
        }
        smcibdev->roce_cq_recv = ib_create_cq(smcibdev->ibdev,
                                              smc_wr_rx_cq_handler, NULL,
                                              smcibdev, &cqattr);
        rc = PTR_ERR_OR_ZERO(smcibdev->roce_cq_recv);
        if (IS_ERR(smcibdev->roce_cq_recv)) {
                smcibdev->roce_cq_recv = NULL;
                goto err;
        }
        INIT_IB_EVENT_HANDLER(&smcibdev->event_handler, smcibdev->ibdev,
                              smc_ib_global_event_handler);
        ib_register_event_handler(&smcibdev->event_handler);
        smc_wr_add_dev(smcibdev);
        smcibdev->initialized = 1;
        return rc;

err:
        ib_destroy_cq(smcibdev->roce_cq_send);
        return rc;
}

static void smc_ib_cleanup_per_ibdev(struct smc_ib_device *smcibdev)
{
        if (!smcibdev->initialized)
                return;
        smc_wr_remove_dev(smcibdev);
        ib_unregister_event_handler(&smcibdev->event_handler);
        ib_destroy_cq(smcibdev->roce_cq_recv);
        ib_destroy_cq(smcibdev->roce_cq_send);
}

static struct ib_client smc_ib_client;

/* callback function for ib_register_client() */
static void smc_ib_add_dev(struct ib_device *ibdev)
{
        struct smc_ib_device *smcibdev;

        if (ibdev->node_type != RDMA_NODE_IB_CA)
                return;

        smcibdev = kzalloc(sizeof(*smcibdev), GFP_KERNEL);
        if (!smcibdev)
                return;

        smcibdev->ibdev = ibdev;
        INIT_WORK(&smcibdev->port_event_work, smc_ib_port_event_work);

        spin_lock(&smc_ib_devices.lock);
        list_add_tail(&smcibdev->list, &smc_ib_devices.list);
        spin_unlock(&smc_ib_devices.lock);
        ib_set_client_data(ibdev, &smc_ib_client, smcibdev);
}

/* callback function for ib_register_client() */
static void smc_ib_remove_dev(struct ib_device *ibdev, void *client_data)
{
        struct smc_ib_device *smcibdev;

        smcibdev = ib_get_client_data(ibdev, &smc_ib_client);
        ib_set_client_data(ibdev, &smc_ib_client, NULL);
        spin_lock(&smc_ib_devices.lock);
        list_del_init(&smcibdev->list); /* remove from smc_ib_devices */
        spin_unlock(&smc_ib_devices.lock);
        smc_pnet_remove_by_ibdev(smcibdev);
        smc_ib_cleanup_per_ibdev(smcibdev);
        kfree(smcibdev);
}

static struct ib_client smc_ib_client = {
        .name   = "smc_ib",
        .add    = smc_ib_add_dev,
        .remove = smc_ib_remove_dev,
};

int __init smc_ib_register_client(void)
{
        return ib_register_client(&smc_ib_client);
}

void smc_ib_unregister_client(void)
{
        ib_unregister_client(&smc_ib_client);
}