// SPDX-License-Identifier: GPL-2.0
/* Shared Memory Communications Direct over ISM devices (SMC-D)
 *
 * Functions for ISM device.
 *
 * Copyright IBM Corp. 2018
 */

#include <linux/spinlock.h>
#include <linux/slab.h>
#include <asm/page.h>

#include "smc.h"
#include "smc_core.h"
#include "smc_ism.h"
#include "smc_pnet.h"

struct smcd_dev_list smcd_dev_list = {
        .list = LIST_HEAD_INIT(smcd_dev_list.list),
        .lock = __SPIN_LOCK_UNLOCKED(smcd_dev_list.lock)
};

/* Test if an ISM communication is possible. */
int smc_ism_cantalk(u64 peer_gid, unsigned short vlan_id, struct smcd_dev *smcd)
{
        return smcd->ops->query_remote_gid(smcd, peer_gid, vlan_id ? 1 : 0,
                                           vlan_id);
}

int smc_ism_write(struct smcd_dev *smcd, const struct smc_ism_position *pos,
                  void *data, size_t len)
{
        int rc;

        rc = smcd->ops->move_data(smcd, pos->token, pos->index, pos->signal,
                                  pos->offset, data, len);

        return rc < 0 ? rc : 0;
}

/* Set a connection using this DMBE. */
void smc_ism_set_conn(struct smc_connection *conn)
{
        unsigned long flags;

        spin_lock_irqsave(&conn->lgr->smcd->lock, flags);
        conn->lgr->smcd->conn[conn->rmb_desc->sba_idx] = conn;
        spin_unlock_irqrestore(&conn->lgr->smcd->lock, flags);
}

/* Unset a connection using this DMBE. */
void smc_ism_unset_conn(struct smc_connection *conn)
{
        unsigned long flags;

        if (!conn->rmb_desc)
                return;

        spin_lock_irqsave(&conn->lgr->smcd->lock, flags);
        conn->lgr->smcd->conn[conn->rmb_desc->sba_idx] = NULL;
        spin_unlock_irqrestore(&conn->lgr->smcd->lock, flags);
}

/* Register a VLAN identifier with the ISM device. Use a reference count
 * and add a VLAN identifier only when the first DMB using this VLAN is
 * registered.
 */
int smc_ism_get_vlan(struct smcd_dev *smcd, unsigned short vlanid)
{
        struct smc_ism_vlanid *new_vlan, *vlan;
        unsigned long flags;
        int rc = 0;

        if (!vlanid)                    /* No valid vlan id */
                return -EINVAL;

        /* create new vlan entry, in case we need it */
        new_vlan = kzalloc(sizeof(*new_vlan), GFP_KERNEL);
        if (!new_vlan)
                return -ENOMEM;
        new_vlan->vlanid = vlanid;
        refcount_set(&new_vlan->refcnt, 1);

        /* if there is an existing entry, increase count and return */
        spin_lock_irqsave(&smcd->lock, flags);
        list_for_each_entry(vlan, &smcd->vlan, list) {
                if (vlan->vlanid == vlanid) {
                        refcount_inc(&vlan->refcnt);
                        kfree(new_vlan);
                        goto out;
                }
        }

        /* no existing entry found.
         * add new entry to device; might fail, e.g., if HW limit reached
         */
        if (smcd->ops->add_vlan_id(smcd, vlanid)) {
                kfree(new_vlan);
                rc = -EIO;
                goto out;
        }
        list_add_tail(&new_vlan->list, &smcd->vlan);
out:
        spin_unlock_irqrestore(&smcd->lock, flags);
        return rc;
}

/* Unregister a VLAN identifier with the ISM device. Use a reference count
 * and remove a VLAN identifier only when the last DMB using this VLAN is
 * unregistered.
 */
int smc_ism_put_vlan(struct smcd_dev *smcd, unsigned short vlanid)
{
        struct smc_ism_vlanid *vlan;
        unsigned long flags;
        bool found = false;
        int rc = 0;

        if (!vlanid)                    /* No valid vlan id */
                return -EINVAL;

        spin_lock_irqsave(&smcd->lock, flags);
        list_for_each_entry(vlan, &smcd->vlan, list) {
                if (vlan->vlanid == vlanid) {
                        if (!refcount_dec_and_test(&vlan->refcnt))
                                goto out;
                        found = true;
                        break;
                }
        }
        if (!found) {
                rc = -ENOENT;
                goto out;               /* VLAN id not in table */
        }

        /* Found and the last reference just gone */
        if (smcd->ops->del_vlan_id(smcd, vlanid))
                rc = -EIO;
        list_del(&vlan->list);
        kfree(vlan);
out:
        spin_unlock_irqrestore(&smcd->lock, flags);
        return rc;
}

int smc_ism_unregister_dmb(struct smcd_dev *smcd, struct smc_buf_desc *dmb_desc)
{
        struct smcd_dmb dmb;
        int rc = 0;

        if (!dmb_desc->dma_addr)
                return rc;

        memset(&dmb, 0, sizeof(dmb));
        dmb.dmb_tok = dmb_desc->token;
        dmb.sba_idx = dmb_desc->sba_idx;
        dmb.cpu_addr = dmb_desc->cpu_addr;
        dmb.dma_addr = dmb_desc->dma_addr;
        dmb.dmb_len = dmb_desc->len;
        rc = smcd->ops->unregister_dmb(smcd, &dmb);
        if (!rc || rc == ISM_ERROR) {
                dmb_desc->cpu_addr = NULL;
                dmb_desc->dma_addr = 0;
        }

        return rc;
}

int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
                         struct smc_buf_desc *dmb_desc)
{
        struct smcd_dmb dmb;
        int rc;

        memset(&dmb, 0, sizeof(dmb));
        dmb.dmb_len = dmb_len;
        dmb.sba_idx = dmb_desc->sba_idx;
        dmb.vlan_id = lgr->vlan_id;
        dmb.rgid = lgr->peer_gid;
        rc = lgr->smcd->ops->register_dmb(lgr->smcd, &dmb);
        if (!rc) {
                dmb_desc->sba_idx = dmb.sba_idx;
                dmb_desc->token = dmb.dmb_tok;
                dmb_desc->cpu_addr = dmb.cpu_addr;
                dmb_desc->dma_addr = dmb.dma_addr;
                dmb_desc->len = dmb.dmb_len;
        }
        return rc;
}

struct smc_ism_event_work {
        struct work_struct work;
        struct smcd_dev *smcd;
        struct smcd_event event;
};

#define ISM_EVENT_REQUEST               0x0001
#define ISM_EVENT_RESPONSE              0x0002
#define ISM_EVENT_REQUEST_IR            0x00000001
#define ISM_EVENT_CODE_SHUTDOWN         0x80
#define ISM_EVENT_CODE_TESTLINK         0x83

union smcd_sw_event_info {
        u64     info;
        struct {
                u8              uid[SMC_LGR_ID_SIZE];
                unsigned short  vlan_id;
                u16             code;
        };
};

static void smcd_handle_sw_event(struct smc_ism_event_work *wrk)
{
        union smcd_sw_event_info ev_info;

        ev_info.info = wrk->event.info;
        switch (wrk->event.code) {
        case ISM_EVENT_CODE_SHUTDOWN:   /* Peer shut down DMBs */
                smc_smcd_terminate(wrk->smcd, wrk->event.tok, ev_info.vlan_id);
                break;
        case ISM_EVENT_CODE_TESTLINK:   /* Activity timer */
                if (ev_info.code == ISM_EVENT_REQUEST) {
                        ev_info.code = ISM_EVENT_RESPONSE;
                        wrk->smcd->ops->signal_event(wrk->smcd,
                                                     wrk->event.tok,
                                                     ISM_EVENT_REQUEST_IR,
                                                     ISM_EVENT_CODE_TESTLINK,
                                                     ev_info.info);
                        }
                break;
        }
}

int smc_ism_signal_shutdown(struct smc_link_group *lgr)
{
        int rc;
        union smcd_sw_event_info ev_info;

        if (lgr->peer_shutdown)
                return 0;

        memcpy(ev_info.uid, lgr->id, SMC_LGR_ID_SIZE);
        ev_info.vlan_id = lgr->vlan_id;
        ev_info.code = ISM_EVENT_REQUEST;
        rc = lgr->smcd->ops->signal_event(lgr->smcd, lgr->peer_gid,
                                          ISM_EVENT_REQUEST_IR,
                                          ISM_EVENT_CODE_SHUTDOWN,
                                          ev_info.info);
        return rc;
}

/* worker for SMC-D events */
static void smc_ism_event_work(struct work_struct *work)
{
        struct smc_ism_event_work *wrk =
                container_of(work, struct smc_ism_event_work, work);

        switch (wrk->event.type) {
        case ISM_EVENT_GID:     /* GID event, token is peer GID */
                smc_smcd_terminate(wrk->smcd, wrk->event.tok, VLAN_VID_MASK);
                break;
        case ISM_EVENT_DMB:
                break;
        case ISM_EVENT_SWR:     /* Software defined event */
                smcd_handle_sw_event(wrk);
                break;
        }
        kfree(wrk);
}

static void smcd_release(struct device *dev)
{
        struct smcd_dev *smcd = container_of(dev, struct smcd_dev, dev);

        kfree(smcd->conn);
        kfree(smcd);
}

struct smcd_dev *smcd_alloc_dev(struct device *parent, const char *name,
                                const struct smcd_ops *ops, int max_dmbs)
{
        struct smcd_dev *smcd;

        smcd = kzalloc(sizeof(*smcd), GFP_KERNEL);
        if (!smcd)
                return NULL;
        smcd->conn = kcalloc(max_dmbs, sizeof(struct smc_connection *),
                             GFP_KERNEL);
        if (!smcd->conn) {
                kfree(smcd);
                return NULL;
        }

        smcd->dev.parent = parent;
        smcd->dev.release = smcd_release;
        device_initialize(&smcd->dev);
        dev_set_name(&smcd->dev, name);
        smcd->ops = ops;
        smc_pnetid_by_dev_port(parent, 0, smcd->pnetid);

        spin_lock_init(&smcd->lock);
        spin_lock_init(&smcd->lgr_lock);
        INIT_LIST_HEAD(&smcd->vlan);
        INIT_LIST_HEAD(&smcd->lgr_list);
        init_waitqueue_head(&smcd->lgrs_deleted);
        smcd->event_wq = alloc_ordered_workqueue("ism_evt_wq-%s)",
                                                 WQ_MEM_RECLAIM, name);
        if (!smcd->event_wq) {
                kfree(smcd->conn);
                kfree(smcd);
                return NULL;
        }
        return smcd;
}
EXPORT_SYMBOL_GPL(smcd_alloc_dev);

int smcd_register_dev(struct smcd_dev *smcd)
{
        spin_lock(&smcd_dev_list.lock);
        list_add_tail(&smcd->list, &smcd_dev_list.list);
        spin_unlock(&smcd_dev_list.lock);

        return device_add(&smcd->dev);
}
EXPORT_SYMBOL_GPL(smcd_register_dev);

void smcd_unregister_dev(struct smcd_dev *smcd)
{
        spin_lock(&smcd_dev_list.lock);
        list_del_init(&smcd->list);
        spin_unlock(&smcd_dev_list.lock);
        smcd->going_away = 1;
        smc_smcd_terminate_all(smcd);
        flush_workqueue(smcd->event_wq);
        destroy_workqueue(smcd->event_wq);

        device_del(&smcd->dev);
}
EXPORT_SYMBOL_GPL(smcd_unregister_dev);

void smcd_free_dev(struct smcd_dev *smcd)
{
        put_device(&smcd->dev);
}
EXPORT_SYMBOL_GPL(smcd_free_dev);

/* SMCD Device event handler. Called from ISM device interrupt handler.
 * Parameters are smcd device pointer,
 * - event->type (0 --> DMB, 1 --> GID),
 * - event->code (event code),
 * - event->tok (either DMB token when event type 0, or GID when event type 1)
 * - event->time (time of day)
 * - event->info (debug info).
 *
 * Context:
 * - Function called in IRQ context from ISM device driver event handler.
 */
void smcd_handle_event(struct smcd_dev *smcd, struct smcd_event *event)
{
        struct smc_ism_event_work *wrk;

        if (smcd->going_away)
                return;
        /* copy event to event work queue, and let it be handled there */
        wrk = kmalloc(sizeof(*wrk), GFP_ATOMIC);
        if (!wrk)
                return;
        INIT_WORK(&wrk->work, smc_ism_event_work);
        wrk->smcd = smcd;
        wrk->event = *event;
        queue_work(smcd->event_wq, &wrk->work);
}
EXPORT_SYMBOL_GPL(smcd_handle_event);

/* SMCD Device interrupt handler. Called from ISM device interrupt handler.
 * Parameters are smcd device pointer and DMB number. Find the connection and
 * schedule the tasklet for this connection.
 *
 * Context:
 * - Function called in IRQ context from ISM device driver IRQ handler.
 */
void smcd_handle_irq(struct smcd_dev *smcd, unsigned int dmbno)
{
        struct smc_connection *conn = NULL;
        unsigned long flags;

        spin_lock_irqsave(&smcd->lock, flags);
        conn = smcd->conn[dmbno];
        if (conn && !conn->killed)
                tasklet_schedule(&conn->rx_tsklet);
        spin_unlock_irqrestore(&smcd->lock, flags);
}
EXPORT_SYMBOL_GPL(smcd_handle_irq);