/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include "rge.h"

#define U32TOPTR(x)     ((void *)(uintptr_t)(uint32_t)(x))
#define PTRTOU32(x)     ((uint32_t)(uintptr_t)(void *)(x))

/*
 * ========== RX side routines ==========
 */

#define RGE_DBG         RGE_DBG_RECV    /* debug flag for this code     */

static uint32_t
rge_atomic_reserve(uint32_t *count_p, uint32_t n)
{
        uint32_t oldval;
        uint32_t newval;

        /* ATOMICALLY */
        do {
                oldval = *count_p;
                newval = oldval - n;
                if (oldval <= n)
                        return (0);             /* no resources left    */
        } while (atomic_cas_32(count_p, oldval, newval) != oldval);

        return (newval);
}

/*
 * Atomically increment a counter
 */
static void
rge_atomic_renounce(uint32_t *count_p, uint32_t n)
{
        uint32_t oldval;
        uint32_t newval;

        /* ATOMICALLY */
        do {
                oldval = *count_p;
                newval = oldval + n;
        } while (atomic_cas_32(count_p, oldval, newval) != oldval);
}

/*
 * Callback code invoked from STREAMs when the recv data buffer is free
 * for recycling.
 */
void
rge_rx_recycle(caddr_t arg)
{
        rge_t *rgep;
        dma_buf_t *rx_buf;
        sw_rbd_t *free_srbdp;
        uint32_t slot_recy;

        rx_buf = (dma_buf_t *)arg;
        rgep = (rge_t *)rx_buf->private;

        /*
         * In rge_unattach() and rge_attach(), this callback function will
         * also be called to free mp in rge_fini_rings() and rge_init_rings().
         * In such situation, we shouldn't do below desballoc(), otherwise,
         * there'll be memory leak.
         */
        if (rgep->rge_mac_state == RGE_MAC_UNATTACH ||
            rgep->rge_mac_state == RGE_MAC_ATTACH)
                return;

        /*
         * Recycle the data buffer again
         * and fill them in free ring
         */
        rx_buf->mp = desballoc(DMA_VPTR(rx_buf->pbuf),
            rgep->rxbuf_size, 0, &rx_buf->rx_recycle);
        if (rx_buf->mp == NULL) {
                rge_problem(rgep, "rge_rx_recycle: desballoc() failed");
                return;
        }
        mutex_enter(rgep->rc_lock);
        slot_recy = rgep->rc_next;
        free_srbdp = &rgep->free_srbds[slot_recy];

        ASSERT(free_srbdp->rx_buf == NULL);
        free_srbdp->rx_buf = rx_buf;
        rgep->rc_next = NEXT(slot_recy, RGE_BUF_SLOTS);
        rge_atomic_renounce(&rgep->rx_free, 1);
        if (rgep->rx_bcopy && rgep->rx_free == RGE_BUF_SLOTS)
                rgep->rx_bcopy = B_FALSE;
        ASSERT(rgep->rx_free <= RGE_BUF_SLOTS);

        mutex_exit(rgep->rc_lock);
}

static int
rge_rx_refill(rge_t *rgep, uint32_t slot)
{
        dma_buf_t *free_buf;
        rge_bd_t *hw_rbd_p;
        sw_rbd_t *srbdp;
        uint32_t free_slot;

        srbdp = &rgep->sw_rbds[slot];
        hw_rbd_p = &rgep->rx_ring[slot];
        free_slot = rgep->rf_next;
        free_buf = rgep->free_srbds[free_slot].rx_buf;
        if (free_buf != NULL) {
                srbdp->rx_buf = free_buf;
                rgep->free_srbds[free_slot].rx_buf = NULL;
                hw_rbd_p->host_buf_addr = RGE_BSWAP_32(rgep->head_room +
                    + free_buf->pbuf.cookie.dmac_laddress);
                hw_rbd_p->host_buf_addr_hi =
                    RGE_BSWAP_32(free_buf->pbuf.cookie.dmac_laddress >> 32);
                rgep->rf_next = NEXT(free_slot, RGE_BUF_SLOTS);
                return (1);
        } else {
                /*
                 * This situation shouldn't happen
                 */
                rge_problem(rgep, "rge_rx_refill: free buffer %d is NULL",
                    free_slot);
                rgep->rx_bcopy = B_TRUE;
                return (0);
        }
}

static mblk_t *
rge_receive_packet(rge_t *rgep, uint32_t slot)
{
        rge_bd_t *hw_rbd_p;
        sw_rbd_t *srbdp;
        uchar_t *dp;
        mblk_t *mp;
        uint8_t *rx_ptr;
        uint32_t rx_status;
        uint_t packet_len;
        uint_t minsize;
        uint_t maxsize;
        uint32_t proto;
        uint32_t pflags;
        struct ether_vlan_header *ehp;
        uint16_t vtag = 0;

        hw_rbd_p = &rgep->rx_ring[slot];
        srbdp = &rgep->sw_rbds[slot];

        /*
         * Read receive status
         */
        rx_status = RGE_BSWAP_32(hw_rbd_p->flags_len) & RBD_FLAGS_MASK;

        /*
         * Handle error packet
         */
        if (!(rx_status & BD_FLAG_PKT_END)) {
                RGE_DEBUG(("rge_receive_packet: not a complete packat"));
                return (NULL);
        }
        if (rx_status & RBD_FLAG_ERROR) {
                if (rx_status & RBD_FLAG_CRC_ERR)
                        rgep->stats.crc_err++;
                if (rx_status & RBD_FLAG_RUNT)
                        rgep->stats.in_short++;
                /*
                 * Set chip_error flag to reset chip:
                 * (suggested in Realtek programming guide.)
                 */
                RGE_DEBUG(("rge_receive_packet: error packet, status = %x",
                    rx_status));
                mutex_enter(rgep->genlock);
                rgep->rge_chip_state = RGE_CHIP_ERROR;
                mutex_exit(rgep->genlock);
                return (NULL);
        }

        /*
         * Handle size error packet
         */
        packet_len = RGE_BSWAP_32(hw_rbd_p->flags_len) & RBD_LEN_MASK;
        packet_len -= ETHERFCSL;
        minsize = ETHERMIN;
        pflags = RGE_BSWAP_32(hw_rbd_p->vlan_tag);
        if (pflags & RBD_VLAN_PKT)
                minsize -= VLAN_TAGSZ;
        maxsize = rgep->ethmax_size;
        if (packet_len < minsize || packet_len > maxsize) {
                RGE_DEBUG(("rge_receive_packet: len err = %d", packet_len));
                return (NULL);
        }

        DMA_SYNC(srbdp->rx_buf->pbuf, DDI_DMA_SYNC_FORKERNEL);
        if (rgep->rx_bcopy || packet_len <= RGE_RECV_COPY_SIZE ||
            !rge_atomic_reserve(&rgep->rx_free, 1)) {
                /*
                 * Allocate buffer to receive this good packet
                 */
                mp = allocb(packet_len + RGE_HEADROOM, 0);
                if (mp == NULL) {
                        RGE_DEBUG(("rge_receive_packet: allocate buffer fail"));
                        rgep->stats.no_rcvbuf++;
                        return (NULL);
                }

                /*
                 * Copy the data found into the new cluster
                 */
                rx_ptr = DMA_VPTR(srbdp->rx_buf->pbuf);
                mp->b_rptr = dp = mp->b_rptr + RGE_HEADROOM;
                bcopy(rx_ptr + rgep->head_room, dp, packet_len);
                mp->b_wptr = dp + packet_len;
        } else {
                mp = srbdp->rx_buf->mp;
                mp->b_rptr += rgep->head_room;
                mp->b_wptr = mp->b_rptr + packet_len;
                mp->b_next = mp->b_cont = NULL;
                /*
                 * Refill the current receive bd buffer
                 *   if fails, will just keep the mp.
                 */
                if (!rge_rx_refill(rgep, slot))
                        return (NULL);
        }
        rgep->stats.rbytes += packet_len;
        rgep->stats.rpackets ++;

        /*
         * VLAN packet ?
         */
        if (pflags & RBD_VLAN_PKT)
                vtag = pflags & RBD_VLAN_TAG;
        if (vtag) {
                vtag = TCI_CHIP2OS(vtag);
                /*
                 * As h/w strips the VLAN tag from incoming packet, we need
                 * insert VLAN tag into this packet before send up here.
                 */
                (void) memmove(mp->b_rptr - VLAN_TAGSZ, mp->b_rptr,
                    2 * ETHERADDRL);
                mp->b_rptr -= VLAN_TAGSZ;
                ehp = (struct ether_vlan_header *)mp->b_rptr;
                ehp->ether_tpid = htons(ETHERTYPE_VLAN);
                ehp->ether_tci = htons(vtag);
                rgep->stats.rbytes += VLAN_TAGSZ;
        }

        /*
         * Check h/w checksum offload status
         */
        pflags = 0;
        proto = rx_status & RBD_FLAG_PROTOCOL;
        if ((proto == RBD_FLAG_TCP && !(rx_status & RBD_TCP_CKSUM_ERR)) ||
            (proto == RBD_FLAG_UDP && !(rx_status & RBD_UDP_CKSUM_ERR)))
                pflags |= HCK_FULLCKSUM_OK;
        if (proto != RBD_FLAG_NONE_IP && !(rx_status & RBD_IP_CKSUM_ERR))
                pflags |= HCK_IPV4_HDRCKSUM_OK;
        if (pflags != 0)  {
                mac_hcksum_set(mp, 0, 0, 0, 0, pflags);
        }

        return (mp);
}

/*
 * Accept the packets received in rx ring.
 *
 * Returns a chain of mblks containing the received data, to be
 * passed up to mac_rx().
 * The routine returns only when a complete scan has been performed
 * without finding any packets to receive.
 * This function must SET the OWN bit of BD to indicate the packets
 * it has accepted from the ring.
 */
static mblk_t *
rge_receive_ring(rge_t *rgep)
{
        rge_bd_t *hw_rbd_p;
        mblk_t *head;
        mblk_t **tail;
        mblk_t *mp;
        uint32_t slot;

        ASSERT(mutex_owned(rgep->rx_lock));

        /*
         * Sync (all) the receive ring descriptors
         * before accepting the packets they describe
         */
        DMA_SYNC(rgep->rx_desc, DDI_DMA_SYNC_FORKERNEL);
        slot = rgep->rx_next;
        hw_rbd_p = &rgep->rx_ring[slot];
        head = NULL;
        tail = &head;

        while (!(hw_rbd_p->flags_len & RGE_BSWAP_32(BD_FLAG_HW_OWN))) {
                if ((mp = rge_receive_packet(rgep, slot)) != NULL) {
                        *tail = mp;
                        tail = &mp->b_next;
                }

                /*
                 * Clear RBD flags
                 */
                hw_rbd_p->flags_len =
                    RGE_BSWAP_32(rgep->rxbuf_size - rgep->head_room);
                HW_RBD_INIT(hw_rbd_p, slot);
                slot = NEXT(slot, RGE_RECV_SLOTS);
                hw_rbd_p = &rgep->rx_ring[slot];
        }

        rgep->rx_next = slot;
        return (head);
}

/*
 * Receive all ready packets.
 */
void
rge_receive(rge_t *rgep)
{
        mblk_t *mp;

        mutex_enter(rgep->rx_lock);
        mp = rge_receive_ring(rgep);
        mutex_exit(rgep->rx_lock);

        if (mp != NULL)
                mac_rx(rgep->mh, NULL, mp);
}


#undef  RGE_DBG
#define RGE_DBG         RGE_DBG_SEND    /* debug flag for this code     */


/*
 * ========== Send-side recycle routines ==========
 */
static uint32_t
rge_send_claim(rge_t *rgep)
{
        uint32_t slot;
        uint32_t next;

        mutex_enter(rgep->tx_lock);
        slot = rgep->tx_next;
        next = NEXT(slot, RGE_SEND_SLOTS);
        rgep->tx_next = next;
        rgep->tx_flow++;
        mutex_exit(rgep->tx_lock);

        /*
         * We check that our invariants still hold:
         * +    the slot and next indexes are in range
         * +    the slot must not be the last one (i.e. the *next*
         *      index must not match the next-recycle index), 'cos
         *      there must always be at least one free slot in a ring
         */
        ASSERT(slot < RGE_SEND_SLOTS);
        ASSERT(next < RGE_SEND_SLOTS);
        ASSERT(next != rgep->tc_next);

        return (slot);
}

/*
 * We don't want to call this function every time after a successful
 * h/w transmit done in ISR.  Instead, we call this function in the
 * rge_send() when there're few or no free tx BDs remained.
 */
void
rge_send_recycle(rge_t *rgep)
{
        rge_bd_t *hw_sbd_p;
        uint32_t tc_tail;
        uint32_t tc_head;
        uint32_t n;

        mutex_enter(rgep->tc_lock);
        tc_head = rgep->tc_next;
        tc_tail = rgep->tc_tail;
        if (tc_head == tc_tail)
                goto resched;

        do {
                tc_tail = LAST(tc_tail, RGE_SEND_SLOTS);
                hw_sbd_p = &rgep->tx_ring[tc_tail];
                if (tc_tail == tc_head) {
                        if (hw_sbd_p->flags_len &
                            RGE_BSWAP_32(BD_FLAG_HW_OWN)) {
                                /*
                                 * Recyled nothing: bump the watchdog counter,
                                 * thus guaranteeing that it's nonzero
                                 * (watchdog activated).
                                 */
                                if (rgep->watchdog == 0)
                                        rgep->watchdog = 1;
                                mutex_exit(rgep->tc_lock);
                                return;
                        }
                        break;
                }
        } while (hw_sbd_p->flags_len & RGE_BSWAP_32(BD_FLAG_HW_OWN));

        /*
         * Recyled something :-)
         */
        rgep->tc_next = NEXT(tc_tail, RGE_SEND_SLOTS);
        n = rgep->tc_next - tc_head;
        if (rgep->tc_next < tc_head)
                n += RGE_SEND_SLOTS;
        rge_atomic_renounce(&rgep->tx_free, n);
        rgep->watchdog = 0;
        ASSERT(rgep->tx_free <= RGE_SEND_SLOTS);

resched:
        mutex_exit(rgep->tc_lock);
        if (rgep->resched_needed &&
            rgep->rge_mac_state == RGE_MAC_STARTED) {
                rgep->resched_needed = B_FALSE;
                mac_tx_update(rgep->mh);
        }
}

/*
 * Send a message by copying it into a preallocated (and premapped) buffer
 */
static void
rge_send_copy(rge_t *rgep, mblk_t *mp, uint16_t tci)
{
        rge_bd_t *hw_sbd_p;
        sw_sbd_t *ssbdp;
        mblk_t *bp;
        char *txb;
        uint32_t slot;
        size_t totlen;
        size_t mblen;
        uint32_t pflags;
        struct ether_header *ethhdr;
        struct ip *ip_hdr;

        /*
         * IMPORTANT:
         *      Up to the point where it claims a place, a send_msg()
         *      routine can indicate failure by returning B_FALSE.  Once it's
         *      claimed a place, it mustn't fail.
         *
         * In this version, there's no setup to be done here, and there's
         * nothing that can fail, so we can go straight to claiming our
         * already-reserved place on the train.
         *
         * This is the point of no return!
         */
        slot = rge_send_claim(rgep);
        ssbdp = &rgep->sw_sbds[slot];

        /*
         * Copy the data into a pre-mapped buffer, which avoids the
         * overhead (and complication) of mapping/unmapping STREAMS
         * buffers and keeping hold of them until the DMA has completed.
         *
         * Because all buffers are the same size, and larger than the
         * longest single valid message, we don't have to bother about
         * splitting the message across multiple buffers either.
         */
        txb = DMA_VPTR(ssbdp->pbuf);
        totlen = 0;
        bp = mp;
        if (tci != 0) {
                /*
                 * Do not copy the vlan tag
                 */
                bcopy(bp->b_rptr, txb, 2 * ETHERADDRL);
                txb += 2 * ETHERADDRL;
                totlen += 2 * ETHERADDRL;
                mblen = MBLKL(bp);
                ASSERT(mblen >= 2 * ETHERADDRL + VLAN_TAGSZ);
                mblen -= 2 * ETHERADDRL + VLAN_TAGSZ;
                if ((totlen += mblen) <= rgep->ethmax_size) {
                        bcopy(bp->b_rptr + 2 * ETHERADDRL + VLAN_TAGSZ,
                            txb, mblen);
                        txb += mblen;
                }
                bp = bp->b_cont;
                rgep->stats.obytes += VLAN_TAGSZ;
        }
        for (; bp != NULL; bp = bp->b_cont) {
                mblen = MBLKL(bp);
                if ((totlen += mblen) <= rgep->ethmax_size) {
                        bcopy(bp->b_rptr, txb, mblen);
                        txb += mblen;
                }
        }
        rgep->stats.obytes += totlen;
        rgep->stats.tx_pre_ismax = rgep->stats.tx_cur_ismax;
        if (totlen == rgep->ethmax_size)
                rgep->stats.tx_cur_ismax = B_TRUE;
        else
                rgep->stats.tx_cur_ismax = B_FALSE;

        /*
         * We'e reached the end of the chain; and we should have
         * collected no more than ETHERMAX bytes into our buffer.
         */
        ASSERT(bp == NULL);
        ASSERT(totlen <= rgep->ethmax_size);
        DMA_SYNC(ssbdp->pbuf, DDI_DMA_SYNC_FORDEV);

        /*
         * Update the hardware send buffer descriptor flags
         */
        hw_sbd_p = &rgep->tx_ring[slot];
        ASSERT(hw_sbd_p == ssbdp->desc.mem_va);
        hw_sbd_p->flags_len = RGE_BSWAP_32(totlen & SBD_LEN_MASK);
        if (tci != 0) {
                tci = TCI_OS2CHIP(tci);
                hw_sbd_p->vlan_tag = RGE_BSWAP_32(tci);
                hw_sbd_p->vlan_tag |= RGE_BSWAP_32(SBD_VLAN_PKT);
        } else {
                hw_sbd_p->vlan_tag = 0;
        }

        /*
         * h/w checksum offload flags
         */
        mac_hcksum_get(mp, NULL, NULL, NULL, NULL, &pflags);
        if (pflags & HCK_FULLCKSUM) {
                ASSERT(totlen >= sizeof (struct ether_header) +
                    sizeof (struct ip));
                ethhdr = (struct ether_header *)(DMA_VPTR(ssbdp->pbuf));
                /*
                 * Is the packet an IP(v4) packet?
                 */
                if (ntohs(ethhdr->ether_type) == ETHERTYPE_IP) {
                        ip_hdr = (struct ip *)
                            ((uint8_t *)DMA_VPTR(ssbdp->pbuf) +
                            sizeof (struct ether_header));
                        if (ip_hdr->ip_p == IPPROTO_TCP)
                                hw_sbd_p->flags_len |=
                                    RGE_BSWAP_32(SBD_FLAG_TCP_CKSUM);
                        else if (ip_hdr->ip_p == IPPROTO_UDP)
                                hw_sbd_p->flags_len |=
                                    RGE_BSWAP_32(SBD_FLAG_UDP_CKSUM);
                }
        }
        if (pflags & HCK_IPV4_HDRCKSUM)
                hw_sbd_p->flags_len |= RGE_BSWAP_32(SBD_FLAG_IP_CKSUM);

        HW_SBD_SET(hw_sbd_p, slot);

        /*
         * We're done.
         * The message can be freed right away, as we've already
         * copied the contents ...
         */
        freemsg(mp);
}

static boolean_t
rge_send(rge_t *rgep, mblk_t *mp)
{
        struct ether_vlan_header *ehp;
        uint16_t tci;

        ASSERT(mp->b_next == NULL);

        /*
         * Try to reserve a place in the transmit ring.
         */
        if (!rge_atomic_reserve(&rgep->tx_free, 1)) {
                RGE_DEBUG(("rge_send: no free slots"));
                rgep->stats.defer++;
                rgep->resched_needed = B_TRUE;
                return (B_FALSE);
        }

        /*
         * Determine if the packet is VLAN tagged.
         */
        ASSERT(MBLKL(mp) >= sizeof (struct ether_header));
        tci = 0;
        ehp = (struct ether_vlan_header *)mp->b_rptr;
        if (ehp->ether_tpid == htons(ETHERTYPE_VLAN))
                tci = ntohs(ehp->ether_tci);

        /*
         * We've reserved a place :-)
         * These ASSERTions check that our invariants still hold:
         *      there must still be at least one free place
         *      there must be at least one place NOT free (ours!)
         */
        ASSERT(rgep->tx_free < RGE_SEND_SLOTS);
        rge_send_copy(rgep, mp, tci);

        /*
         * Trigger chip h/w transmit ...
         */
        mutex_enter(rgep->tx_lock);
        if (--rgep->tx_flow == 0) {
                DMA_SYNC(rgep->tx_desc, DDI_DMA_SYNC_FORDEV);
                rgep->tc_tail = rgep->tx_next;
        }
        rgep->stats.opackets++;
        mutex_exit(rgep->tx_lock);

        return (B_TRUE);
}

uint_t
rge_reschedule(caddr_t arg1, caddr_t arg2)
{
        rge_t *rgep;

        rgep = (rge_t *)arg1;
        _NOTE(ARGUNUSED(arg2))

        rge_send_recycle(rgep);

        if (rgep->chipid.is_pcie && rgep->tx_free != RGE_SEND_SLOTS) {
                /*
                 * It's observed that in current Realtek PCI-E chips, tx
                 * request of the second fragment for upper layer packets
                 * will be ignored if the hardware transmission is in
                 * progress and will not be processed when the tx engine
                 * is idle. So one solution is to re-issue the requests
                 * if there are untransmitted packets after tx interrupts
                 * occur.
                 */
                rge_tx_trigger(rgep);
        }

        return (DDI_INTR_CLAIMED);
}

/*
 * rge_m_tx() - send a chain of packets
 */
mblk_t *
rge_m_tx(void *arg, mblk_t *mp)
{
        rge_t *rgep = arg;              /* private device info  */
        mblk_t *next;
        mblk_t *mp_org = mp;

        ASSERT(mp != NULL);

        rw_enter(rgep->errlock, RW_READER);
        if ((rgep->rge_mac_state != RGE_MAC_STARTED) ||
            (rgep->rge_chip_state != RGE_CHIP_RUNNING) ||
            (rgep->param_link_up != LINK_STATE_UP)) {
                rw_exit(rgep->errlock);
                RGE_DEBUG(("rge_m_tx: tx doesn't work"));
                freemsgchain(mp);
                return (NULL);
        }

        while (mp != NULL) {
                next = mp->b_next;
                mp->b_next = NULL;

                if (!rge_send(rgep, mp)) {
                        mp->b_next = next;
                        break;
                }

                mp = next;
        }
        if (mp != mp_org) {
                rge_tx_trigger(rgep);
        }
        rw_exit(rgep->errlock);

        return (mp);
}