/*
 * Copyright (C) 2013 Universita` di Pisa. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/param.h>  /* defines used in kernel.h */
#include <sys/kernel.h> /* types used in module initialization */
#include <sys/conf.h>   /* DEV_MODULE */

#include <sys/devfs.h>

#include <vm/vm.h>      /* vtophys */
#include <vm/pmap.h>    /* vtophys */
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_page2.h>
#include <vm/vm_pager.h>


#include <sys/malloc.h>
#include <sys/socket.h> /* sockaddrs */
#include <sys/event.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/ifq_var.h>
#include <sys/bus.h>    /* bus_dmamap_* */

#include <net/netmap/netmap.h>
#include <net/netmap/netmap_kern.h>
#include <net/netmap/netmap_mem2.h>


/* ======================== FREEBSD-SPECIFIC ROUTINES ================== */

/*
 * Intercept the rx routine in the standard device driver.
 * Second argument is non-zero to intercept, 0 to restore
 */
int
netmap_catch_rx(struct netmap_adapter *na, int intercept)
{
        struct netmap_generic_adapter *gna = (struct netmap_generic_adapter *)na;
        struct ifnet *ifp = na->ifp;

        if (intercept) {
                if (gna->save_if_input) {
                        D("cannot intercept again");
                        return EINVAL; /* already set */
                }
                gna->save_if_input = ifp->if_input;
                ifp->if_input = generic_rx_handler;
        } else {
                if (!gna->save_if_input){
                        D("cannot restore");
                        return EINVAL;  /* not saved */
                }
                ifp->if_input = gna->save_if_input;
                gna->save_if_input = NULL;
        }

        return 0;
}

/*
 * Intercept the packet steering routine in the tx path,
 * so that we can decide which queue is used for an mbuf.
 * Second argument is non-zero to intercept, 0 to restore.
 *
 * XXX see if FreeBSD has such a mechanism
 */
void
netmap_catch_packet_steering(struct netmap_generic_adapter *na, int enable)
{
        if (enable) {
        } else {
        }
}

/* Transmit routine used by generic_netmap_txsync(). Returns 0 on success
 * and non-zero on error (which may be packet drops or other errors).
 * addr and len identify the netmap buffer, m is the (preallocated)
 * mbuf to use for transmissions.
 *
 * We should add a reference to the mbuf so the m_freem() at the end
 * of the transmission does not consume resources.
 *
 * On FreeBSD, and on multiqueue cards, we can force the queue using
 *      if ((m->m_flags & M_FLOWID) != 0)
 *              i = m->m_pkthdr.flowid % adapter->num_queues;
 *      else
 *              i = curcpu % adapter->num_queues;
 *
 */
int
generic_xmit_frame(struct ifnet *ifp, struct mbuf *m,
        void *addr, u_int len, u_int ring_nr)
{
        int ret;

        m->m_len = m->m_pkthdr.len = 0;

        // copy data to the mbuf
        ret = m_copyback2(m, 0, len, addr, M_NOWAIT);
        if (ret != 0)
                return ret;

#if 0
        // inc refcount. We are alone, so we can skip the atomic
        atomic_fetchadd_int(m->m_ext.ref_cnt, 1);
        m->m_flags |= M_FLOWID;
#endif
        m->m_pkthdr.hash = ring_nr;     /* XXX probably not accurate */
        m->m_pkthdr.rcvif = ifp; /* used for tx notification */
        ret = ifq_dispatch(ifp, m, NULL);
        return ret;
}

/*
 * The following two functions are empty until we have a generic
 * way to extract the info from the ifp
 */
int
generic_find_num_desc(struct ifnet *ifp, unsigned int *tx, unsigned int *rx)
{
        D("called");
        return 0;
}

void
generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq)
{
        D("called");
        *txq = 1;
        *rxq = 1;
}

void netmap_mitigation_init(struct netmap_generic_adapter *na)
{
        ND("called");
        na->mit_pending = 0;
}


void netmap_mitigation_start(struct netmap_generic_adapter *na)
{
        ND("called");
}

void netmap_mitigation_restart(struct netmap_generic_adapter *na)
{
        ND("called");
}

int netmap_mitigation_active(struct netmap_generic_adapter *na)
{
        ND("called");
        return 0;
}

void netmap_mitigation_cleanup(struct netmap_generic_adapter *na)
{
        ND("called");
}


/*
 * In order to track whether pages are still mapped, we hook into
 * the standard cdev_pager and intercept the constructor and
 * destructor.
 */

struct netmap_vm_handle_t {
        struct cdev             *dev;
        struct netmap_priv_d    *priv;
};

static int
netmap_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
        struct netmap_vm_handle_t *vmh = handle;
        (void)vmh;
        D("handle %p size %jd prot %d foff %jd",
                handle, (intmax_t)size, prot, (intmax_t)foff);
#if 0
        dev_ref(vmh->dev);
#endif
        return 0;
}


static void
netmap_dev_pager_dtor(void *handle)
{
        struct netmap_vm_handle_t *vmh = handle;
        struct cdev *dev = vmh->dev;
        struct netmap_priv_d *priv = vmh->priv;
        (void)dev;
        D("handle %p", handle);
        netmap_dtor(priv);
        kfree(vmh, M_DEVBUF);
#if 0
        dev_rel(dev);
#endif
}

MALLOC_DEFINE(M_FICT_PAGES, "", "");

static inline vm_page_t
vm_page_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
{
        vm_page_t m;

        m = kmalloc(sizeof(struct vm_page), M_FICT_PAGES, M_WAITOK | M_ZERO);
        vm_page_initfake(m, paddr, memattr);
        return (m);
}

static inline void
vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
{
        KASSERT((m->flags & PG_FICTITIOUS) != 0,
            ("vm_page_updatefake: bad page %p", m));
        m->phys_addr = paddr;
        pmap_page_set_memattr(m, memattr);
}

static int
netmap_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
        int prot, vm_page_t *mres)
{
        struct netmap_vm_handle_t *vmh = object->handle;
        struct netmap_priv_d *priv = vmh->priv;
        vm_paddr_t paddr;
        vm_page_t page;
        vm_memattr_t memattr;
        vm_pindex_t pidx;

        ND("object %p offset %jd prot %d mres %p",
                        object, (intmax_t)offset, prot, mres);
        memattr = object->memattr;
        pidx = OFF_TO_IDX(offset);
        paddr = netmap_mem_ofstophys(priv->np_mref, offset);
        if (paddr == 0)
                return VM_PAGER_FAIL;

        if (((*mres)->flags & PG_FICTITIOUS) != 0) {
                /*
                 * If the passed in result page is a fake page, update it with
                 * the new physical address.
                 */
                page = *mres;
                vm_page_updatefake(page, paddr, memattr);
        } else {
                /*
                 * Replace the passed in reqpage page with our own fake page and
                 * free up the all of the original pages.
                 */
#ifndef VM_OBJECT_WUNLOCK       /* FreeBSD < 10.x */
#define VM_OBJECT_WUNLOCK VM_OBJECT_UNLOCK
#define VM_OBJECT_WLOCK VM_OBJECT_LOCK
#endif /* VM_OBJECT_WUNLOCK */

                VM_OBJECT_WUNLOCK(object);
                page = vm_page_getfake(paddr, memattr);
                VM_OBJECT_WLOCK(object);
                vm_page_free(*mres);
                *mres = page;
                vm_page_insert(page, object, pidx);
        }
        page->valid = VM_PAGE_BITS_ALL;
        return (VM_PAGER_OK);
}


static struct cdev_pager_ops netmap_cdev_pager_ops = {
        .cdev_pg_ctor = netmap_dev_pager_ctor,
        .cdev_pg_dtor = netmap_dev_pager_dtor,
        .cdev_pg_fault = netmap_dev_pager_fault,
};


static int
netmap_mmap_single(struct dev_mmap_single_args *ap)
{
        int error;
        struct cdev *cdev = ap->a_head.a_dev;
        vm_ooffset_t *foff = ap->a_offset;
        vm_object_t *objp = ap->a_object;
        vm_size_t objsize = ap->a_size;
        struct netmap_vm_handle_t *vmh;
        struct netmap_priv_d *priv;
        int prot = ap->a_nprot;
        vm_object_t obj;

        D("cdev %p foff %jd size %jd objp %p prot %d", cdev,
            (intmax_t )*foff, (intmax_t )objsize, objp, prot);

        vmh = kmalloc(sizeof(struct netmap_vm_handle_t), M_DEVBUF,
                              M_NOWAIT | M_ZERO);
        if (vmh == NULL)
                return ENOMEM;
        vmh->dev = cdev;

        NMG_LOCK();
        error = devfs_get_cdevpriv(ap->a_fp, (void**)&priv);
        if (error)
                goto err_unlock;
        vmh->priv = priv;
        priv->np_refcount++;
        NMG_UNLOCK();

        error = netmap_get_memory(priv);
        if (error)
                goto err_deref;

        obj = cdev_pager_allocate(vmh, OBJT_DEVICE,
                &netmap_cdev_pager_ops, objsize, prot,
                *foff, NULL);
        if (obj == NULL) {
                D("cdev_pager_allocate failed");
                error = EINVAL;
                goto err_deref;
        }

        *objp = obj;
        return 0;

err_deref:
        NMG_LOCK();
        priv->np_refcount--;
err_unlock:
        NMG_UNLOCK();
// err:
        kfree(vmh, M_DEVBUF);
        return error;
}


// XXX can we remove this ?
static int
netmap_close(struct dev_close_args *ap)
{
        if (netmap_verbose)
                D("dev %p fflag 0x%x devtype %d",
                        ap->a_head.a_dev, ap->a_fflag, ap->a_devtype);
        return 0;
}


static int
netmap_open(struct dev_open_args *ap)
{
        struct netmap_priv_d *priv;
        int error;

        // XXX wait or nowait ?
        priv = kmalloc(sizeof(struct netmap_priv_d), M_DEVBUF,
                              M_NOWAIT | M_ZERO);
        if (priv == NULL)
                return ENOMEM;

        error = devfs_set_cdevpriv(ap->a_fp, priv, netmap_dtor);
        if (error)
                return error;

        priv->np_refcount = 1;

        return 0;
}


struct dev_ops netmap_cdevsw = {
        { "netmap", 0, 0 },
        .d_open = netmap_open,
        .d_mmap_single = netmap_mmap_single,
        .d_ioctl = netmap_ioctl,
        .d_kqfilter = netmap_kqfilter,
        .d_close = netmap_close,
};


/*
 * Kernel entry point.
 *
 * Initialize/finalize the module and return.
 *
 * Return 0 on success, errno on failure.
 */
static int
netmap_loader(__unused struct module *module, int event, __unused void *arg)
{
        int error = 0;

        switch (event) {
        case MOD_LOAD:
                error = netmap_init();
                break;

        case MOD_UNLOAD:
                netmap_fini();
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}


DEV_MODULE(netmap, netmap_loader, NULL);