/*
 * Copyright (c) 2007, 2008, 2009 QLogic Corporation. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/delay.h>

#include "qib.h"
#include "qib_user_sdma.h"

/* minimum size of header */
#define QIB_USER_SDMA_MIN_HEADER_LENGTH 64
/* expected size of headers (for dma_pool) */
#define QIB_USER_SDMA_EXP_HEADER_LENGTH 64
/* attempt to drain the queue for 5secs */
#define QIB_USER_SDMA_DRAIN_TIMEOUT 500

struct qib_user_sdma_pkt {
        struct list_head list;  /* list element */

        u8  tiddma;             /* if this is NEW tid-sdma */
        u8  largepkt;           /* this is large pkt from kmalloc */
        u16 frag_size;          /* frag size used by PSM */
        u16 index;              /* last header index or push index */
        u16 naddr;              /* dimension of addr (1..3) ... */
        u16 addrlimit;          /* addr array size */
        u16 tidsmidx;           /* current tidsm index */
        u16 tidsmcount;         /* tidsm array item count */
        u16 payload_size;       /* payload size so far for header */
        u32 bytes_togo;         /* bytes for processing */
        u32 counter;            /* sdma pkts queued counter for this entry */
        struct qib_tid_session_member *tidsm;   /* tid session member array */
        struct qib_user_sdma_queue *pq; /* which pq this pkt belongs to */
        u64 added;              /* global descq number of entries */

        struct {
                u16 offset;                     /* offset for kvaddr, addr */
                u16 length;                     /* length in page */
                u16 first_desc;                 /* first desc */
                u16 last_desc;                  /* last desc */
                u16 put_page;                   /* should we put_page? */
                u16 dma_mapped;                 /* is page dma_mapped? */
                u16 dma_length;                 /* for dma_unmap_page() */
                u16 padding;
                struct page *page;              /* may be NULL (coherent mem) */
                void *kvaddr;                   /* FIXME: only for pio hack */
                dma_addr_t addr;
        } addr[4];   /* max pages, any more and we coalesce */
};

struct qib_user_sdma_queue {
        /*
         * pkts sent to dma engine are queued on this
         * list head.  the type of the elements of this
         * list are struct qib_user_sdma_pkt...
         */
        struct list_head sent;

        /*
         * Because above list will be accessed by both process and
         * signal handler, we need a spinlock for it.
         */
        spinlock_t sent_lock ____cacheline_aligned_in_smp;

        /* headers with expected length are allocated from here... */
        char header_cache_name[64];
        struct dma_pool *header_cache;

        /* packets are allocated from the slab cache... */
        char pkt_slab_name[64];
        struct kmem_cache *pkt_slab;

        /* as packets go on the queued queue, they are counted... */
        u32 counter;
        u32 sent_counter;
        /* pending packets, not sending yet */
        u32 num_pending;
        /* sending packets, not complete yet */
        u32 num_sending;
        /* global descq number of entry of last sending packet */
        u64 added;

        /* dma page table */
        struct rb_root dma_pages_root;

        /* protect everything above... */
        struct mutex lock;
};

struct qib_user_sdma_queue *
qib_user_sdma_queue_create(struct device *dev, int unit, int ctxt, int sctxt)
{
        struct qib_user_sdma_queue *pq =
                kmalloc(sizeof(struct qib_user_sdma_queue), GFP_KERNEL);

        if (!pq)
                goto done;

        pq->counter = 0;
        pq->sent_counter = 0;
        pq->num_pending = 0;
        pq->num_sending = 0;
        pq->added = 0;

        INIT_LIST_HEAD(&pq->sent);
        spin_lock_init(&pq->sent_lock);
        mutex_init(&pq->lock);

        snprintf(pq->pkt_slab_name, sizeof(pq->pkt_slab_name),
                 "qib-user-sdma-pkts-%u-%02u.%02u", unit, ctxt, sctxt);
        pq->pkt_slab = kmem_cache_create(pq->pkt_slab_name,
                                         sizeof(struct qib_user_sdma_pkt),
                                         0, 0, NULL);

        if (!pq->pkt_slab)
                goto err_kfree;

        snprintf(pq->header_cache_name, sizeof(pq->header_cache_name),
                 "qib-user-sdma-headers-%u-%02u.%02u", unit, ctxt, sctxt);
        pq->header_cache = dma_pool_create(pq->header_cache_name,
                                           dev,
                                           QIB_USER_SDMA_EXP_HEADER_LENGTH,
                                           4, 0);
        if (!pq->header_cache)
                goto err_slab;

        pq->dma_pages_root = RB_ROOT;

        goto done;

err_slab:
        kmem_cache_destroy(pq->pkt_slab);
err_kfree:
        kfree(pq);
        pq = NULL;

done:
        return pq;
}

static void qib_user_sdma_init_frag(struct qib_user_sdma_pkt *pkt,
                                    int i, u16 offset, u16 len,
                                    u16 first_desc, u16 last_desc,
                                    u16 put_page, u16 dma_mapped,
                                    struct page *page, void *kvaddr,
                                    dma_addr_t dma_addr, u16 dma_length)
{
        pkt->addr[i].offset = offset;
        pkt->addr[i].length = len;
        pkt->addr[i].first_desc = first_desc;
        pkt->addr[i].last_desc = last_desc;
        pkt->addr[i].put_page = put_page;
        pkt->addr[i].dma_mapped = dma_mapped;
        pkt->addr[i].page = page;
        pkt->addr[i].kvaddr = kvaddr;
        pkt->addr[i].addr = dma_addr;
        pkt->addr[i].dma_length = dma_length;
}

static void *qib_user_sdma_alloc_header(struct qib_user_sdma_queue *pq,
                                size_t len, dma_addr_t *dma_addr)
{
        void *hdr;

        if (len == QIB_USER_SDMA_EXP_HEADER_LENGTH)
                hdr = dma_pool_alloc(pq->header_cache, GFP_KERNEL,
                                             dma_addr);
        else
                hdr = NULL;

        if (!hdr) {
                hdr = kmalloc(len, GFP_KERNEL);
                if (!hdr)
                        return NULL;

                *dma_addr = 0;
        }

        return hdr;
}

static int qib_user_sdma_page_to_frags(const struct qib_devdata *dd,
                                       struct qib_user_sdma_queue *pq,
                                       struct qib_user_sdma_pkt *pkt,
                                       struct page *page, u16 put,
                                       u16 offset, u16 len, void *kvaddr)
{
        __le16 *pbc16;
        void *pbcvaddr;
        struct qib_message_header *hdr;
        u16 newlen, pbclen, lastdesc, dma_mapped;
        u32 vcto;
        union qib_seqnum seqnum;
        dma_addr_t pbcdaddr;
        dma_addr_t dma_addr =
                dma_map_page(&dd->pcidev->dev,
                        page, offset, len, DMA_TO_DEVICE);
        int ret = 0;

        if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
                /*
                 * dma mapping error, pkt has not managed
                 * this page yet, return the page here so
                 * the caller can ignore this page.
                 */
                if (put) {
                        put_page(page);
                } else {
                        /* coalesce case */
                        kunmap(page);
                        __free_page(page);
                }
                ret = -ENOMEM;
                goto done;
        }
        offset = 0;
        dma_mapped = 1;


next_fragment:

        /*
         * In tid-sdma, the transfer length is restricted by
         * receiver side current tid page length.
         */
        if (pkt->tiddma && len > pkt->tidsm[pkt->tidsmidx].length)
                newlen = pkt->tidsm[pkt->tidsmidx].length;
        else
                newlen = len;

        /*
         * Then the transfer length is restricted by MTU.
         * the last descriptor flag is determined by:
         * 1. the current packet is at frag size length.
         * 2. the current tid page is done if tid-sdma.
         * 3. there is no more byte togo if sdma.
         */
        lastdesc = 0;
        if ((pkt->payload_size + newlen) >= pkt->frag_size) {
                newlen = pkt->frag_size - pkt->payload_size;
                lastdesc = 1;
        } else if (pkt->tiddma) {
                if (newlen == pkt->tidsm[pkt->tidsmidx].length)
                        lastdesc = 1;
        } else {
                if (newlen == pkt->bytes_togo)
                        lastdesc = 1;
        }

        /* fill the next fragment in this page */
        qib_user_sdma_init_frag(pkt, pkt->naddr, /* index */
                offset, newlen,         /* offset, len */
                0, lastdesc,            /* first last desc */
                put, dma_mapped,        /* put page, dma mapped */
                page, kvaddr,           /* struct page, virt addr */
                dma_addr, len);         /* dma addr, dma length */
        pkt->bytes_togo -= newlen;
        pkt->payload_size += newlen;
        pkt->naddr++;
        if (pkt->naddr == pkt->addrlimit) {
                ret = -EFAULT;
                goto done;
        }

        /* If there is no more byte togo. (lastdesc==1) */
        if (pkt->bytes_togo == 0) {
                /* The packet is done, header is not dma mapped yet.
                 * it should be from kmalloc */
                if (!pkt->addr[pkt->index].addr) {
                        pkt->addr[pkt->index].addr =
                                dma_map_single(&dd->pcidev->dev,
                                        pkt->addr[pkt->index].kvaddr,
                                        pkt->addr[pkt->index].dma_length,
                                        DMA_TO_DEVICE);
                        if (dma_mapping_error(&dd->pcidev->dev,
                                        pkt->addr[pkt->index].addr)) {
                                ret = -ENOMEM;
                                goto done;
                        }
                        pkt->addr[pkt->index].dma_mapped = 1;
                }

                goto done;
        }

        /* If tid-sdma, advance tid info. */
        if (pkt->tiddma) {
                pkt->tidsm[pkt->tidsmidx].length -= newlen;
                if (pkt->tidsm[pkt->tidsmidx].length) {
                        pkt->tidsm[pkt->tidsmidx].offset += newlen;
                } else {
                        pkt->tidsmidx++;
                        if (pkt->tidsmidx == pkt->tidsmcount) {
                                ret = -EFAULT;
                                goto done;
                        }
                }
        }

        /*
         * If this is NOT the last descriptor. (newlen==len)
         * the current packet is not done yet, but the current
         * send side page is done.
         */
        if (lastdesc == 0)
                goto done;

        /*
         * If running this driver under PSM with message size
         * fitting into one transfer unit, it is not possible
         * to pass this line. otherwise, it is a buggggg.
         */

        /*
         * Since the current packet is done, and there are more
         * bytes togo, we need to create a new sdma header, copying
         * from previous sdma header and modify both.
         */
        pbclen = pkt->addr[pkt->index].length;
        pbcvaddr = qib_user_sdma_alloc_header(pq, pbclen, &pbcdaddr);
        if (!pbcvaddr) {
                ret = -ENOMEM;
                goto done;
        }
        /* Copy the previous sdma header to new sdma header */
        pbc16 = (__le16 *)pkt->addr[pkt->index].kvaddr;
        memcpy(pbcvaddr, pbc16, pbclen);

        /* Modify the previous sdma header */
        hdr = (struct qib_message_header *)&pbc16[4];

        /* New pbc length */
        pbc16[0] = cpu_to_le16(le16_to_cpu(pbc16[0])-(pkt->bytes_togo>>2));

        /* New packet length */
        hdr->lrh[2] = cpu_to_be16(le16_to_cpu(pbc16[0]));

        if (pkt->tiddma) {
                /* turn on the header suppression */
                hdr->iph.pkt_flags =
                        cpu_to_le16(le16_to_cpu(hdr->iph.pkt_flags)|0x2);
                /* turn off ACK_REQ: 0x04 and EXPECTED_DONE: 0x20 */
                hdr->flags &= ~(0x04|0x20);
        } else {
                /* turn off extra bytes: 20-21 bits */
                hdr->bth[0] = cpu_to_be32(be32_to_cpu(hdr->bth[0])&0xFFCFFFFF);
                /* turn off ACK_REQ: 0x04 */
                hdr->flags &= ~(0x04);
        }

        /* New kdeth checksum */
        vcto = le32_to_cpu(hdr->iph.ver_ctxt_tid_offset);
        hdr->iph.chksum = cpu_to_le16(QIB_LRH_BTH +
                be16_to_cpu(hdr->lrh[2]) -
                ((vcto>>16)&0xFFFF) - (vcto&0xFFFF) -
                le16_to_cpu(hdr->iph.pkt_flags));

        /* The packet is done, header is not dma mapped yet.
         * it should be from kmalloc */
        if (!pkt->addr[pkt->index].addr) {
                pkt->addr[pkt->index].addr =
                        dma_map_single(&dd->pcidev->dev,
                                pkt->addr[pkt->index].kvaddr,
                                pkt->addr[pkt->index].dma_length,
                                DMA_TO_DEVICE);
                if (dma_mapping_error(&dd->pcidev->dev,
                                pkt->addr[pkt->index].addr)) {
                        ret = -ENOMEM;
                        goto done;
                }
                pkt->addr[pkt->index].dma_mapped = 1;
        }

        /* Modify the new sdma header */
        pbc16 = (__le16 *)pbcvaddr;
        hdr = (struct qib_message_header *)&pbc16[4];

        /* New pbc length */
        pbc16[0] = cpu_to_le16(le16_to_cpu(pbc16[0])-(pkt->payload_size>>2));

        /* New packet length */
        hdr->lrh[2] = cpu_to_be16(le16_to_cpu(pbc16[0]));

        if (pkt->tiddma) {
                /* Set new tid and offset for new sdma header */
                hdr->iph.ver_ctxt_tid_offset = cpu_to_le32(
                        (le32_to_cpu(hdr->iph.ver_ctxt_tid_offset)&0xFF000000) +
                        (pkt->tidsm[pkt->tidsmidx].tid<<QLOGIC_IB_I_TID_SHIFT) +
                        (pkt->tidsm[pkt->tidsmidx].offset>>2));
        } else {
                /* Middle protocol new packet offset */
                hdr->uwords[2] += pkt->payload_size;
        }

        /* New kdeth checksum */
        vcto = le32_to_cpu(hdr->iph.ver_ctxt_tid_offset);
        hdr->iph.chksum = cpu_to_le16(QIB_LRH_BTH +
                be16_to_cpu(hdr->lrh[2]) -
                ((vcto>>16)&0xFFFF) - (vcto&0xFFFF) -
                le16_to_cpu(hdr->iph.pkt_flags));

        /* Next sequence number in new sdma header */
        seqnum.val = be32_to_cpu(hdr->bth[2]);
        if (pkt->tiddma)
                seqnum.seq++;
        else
                seqnum.pkt++;
        hdr->bth[2] = cpu_to_be32(seqnum.val);

        /* Init new sdma header. */
        qib_user_sdma_init_frag(pkt, pkt->naddr, /* index */
                0, pbclen,              /* offset, len */
                1, 0,                   /* first last desc */
                0, 0,                   /* put page, dma mapped */
                NULL, pbcvaddr,         /* struct page, virt addr */
                pbcdaddr, pbclen);      /* dma addr, dma length */
        pkt->index = pkt->naddr;
        pkt->payload_size = 0;
        pkt->naddr++;
        if (pkt->naddr == pkt->addrlimit) {
                ret = -EFAULT;
                goto done;
        }

        /* Prepare for next fragment in this page */
        if (newlen != len) {
                if (dma_mapped) {
                        put = 0;
                        dma_mapped = 0;
                        page = NULL;
                        kvaddr = NULL;
                }
                len -= newlen;
                offset += newlen;

                goto next_fragment;
        }

done:
        return ret;
}

/* we've too many pages in the iovec, coalesce to a single page */
static int qib_user_sdma_coalesce(const struct qib_devdata *dd,
                                  struct qib_user_sdma_queue *pq,
                                  struct qib_user_sdma_pkt *pkt,
                                  const struct iovec *iov,
                                  unsigned long niov)
{
        int ret = 0;
        struct page *page = alloc_page(GFP_KERNEL);
        void *mpage_save;
        char *mpage;
        int i;
        int len = 0;

        if (!page) {
                ret = -ENOMEM;
                goto done;
        }

        mpage = kmap(page);
        mpage_save = mpage;
        for (i = 0; i < niov; i++) {
                int cfur;

                cfur = copy_from_user(mpage,
                                      iov[i].iov_base, iov[i].iov_len);
                if (cfur) {
                        ret = -EFAULT;
                        goto free_unmap;
                }

                mpage += iov[i].iov_len;
                len += iov[i].iov_len;
        }

        ret = qib_user_sdma_page_to_frags(dd, pq, pkt,
                        page, 0, 0, len, mpage_save);
        goto done;

free_unmap:
        kunmap(page);
        __free_page(page);
done:
        return ret;
}

/*
 * How many pages in this iovec element?
 */
static int qib_user_sdma_num_pages(const struct iovec *iov)
{
        const unsigned long addr  = (unsigned long) iov->iov_base;
        const unsigned long  len  = iov->iov_len;
        const unsigned long spage = addr & PAGE_MASK;
        const unsigned long epage = (addr + len - 1) & PAGE_MASK;

        return 1 + ((epage - spage) >> PAGE_SHIFT);
}

static void qib_user_sdma_free_pkt_frag(struct device *dev,
                                        struct qib_user_sdma_queue *pq,
                                        struct qib_user_sdma_pkt *pkt,
                                        int frag)
{
        const int i = frag;

        if (pkt->addr[i].page) {
                /* only user data has page */
                if (pkt->addr[i].dma_mapped)
                        dma_unmap_page(dev,
                                       pkt->addr[i].addr,
                                       pkt->addr[i].dma_length,
                                       DMA_TO_DEVICE);

                if (pkt->addr[i].kvaddr)
                        kunmap(pkt->addr[i].page);

                if (pkt->addr[i].put_page)
                        put_page(pkt->addr[i].page);
                else
                        __free_page(pkt->addr[i].page);
        } else if (pkt->addr[i].kvaddr) {
                /* for headers */
                if (pkt->addr[i].dma_mapped) {
                        /* from kmalloc & dma mapped */
                        dma_unmap_single(dev,
                                       pkt->addr[i].addr,
                                       pkt->addr[i].dma_length,
                                       DMA_TO_DEVICE);
                        kfree(pkt->addr[i].kvaddr);
                } else if (pkt->addr[i].addr) {
                        /* free coherent mem from cache... */
                        dma_pool_free(pq->header_cache,
                              pkt->addr[i].kvaddr, pkt->addr[i].addr);
                } else {
                        /* from kmalloc but not dma mapped */
                        kfree(pkt->addr[i].kvaddr);
                }
        }
}

/* return number of pages pinned... */
static int qib_user_sdma_pin_pages(const struct qib_devdata *dd,
                                   struct qib_user_sdma_queue *pq,
                                   struct qib_user_sdma_pkt *pkt,
                                   unsigned long addr, int tlen, int npages)
{
        struct page *pages[8];
        int i, j;
        int ret = 0;

        while (npages) {
                if (npages > 8)
                        j = 8;
                else
                        j = npages;

                ret = get_user_pages_fast(addr, j, 0, pages);
                if (ret != j) {
                        i = 0;
                        j = ret;
                        ret = -ENOMEM;
                        goto free_pages;
                }

                for (i = 0; i < j; i++) {
                        /* map the pages... */
                        unsigned long fofs = addr & ~PAGE_MASK;
                        int flen = ((fofs + tlen) > PAGE_SIZE) ?
                                (PAGE_SIZE - fofs) : tlen;

                        ret = qib_user_sdma_page_to_frags(dd, pq, pkt,
                                pages[i], 1, fofs, flen, NULL);
                        if (ret < 0) {
                                /* current page has beed taken
                                 * care of inside above call.
                                 */
                                i++;
                                goto free_pages;
                        }

                        addr += flen;
                        tlen -= flen;
                }

                npages -= j;
        }

        goto done;

        /* if error, return all pages not managed by pkt */
free_pages:
        while (i < j)
                put_page(pages[i++]);

done:
        return ret;
}

static int qib_user_sdma_pin_pkt(const struct qib_devdata *dd,
                                 struct qib_user_sdma_queue *pq,
                                 struct qib_user_sdma_pkt *pkt,
                                 const struct iovec *iov,
                                 unsigned long niov)
{
        int ret = 0;
        unsigned long idx;

        for (idx = 0; idx < niov; idx++) {
                const int npages = qib_user_sdma_num_pages(iov + idx);
                const unsigned long addr = (unsigned long) iov[idx].iov_base;

                ret = qib_user_sdma_pin_pages(dd, pq, pkt, addr,
                                              iov[idx].iov_len, npages);
                if (ret < 0)
                        goto free_pkt;
        }

        goto done;

free_pkt:
        /* we need to ignore the first entry here */
        for (idx = 1; idx < pkt->naddr; idx++)
                qib_user_sdma_free_pkt_frag(&dd->pcidev->dev, pq, pkt, idx);

        /* need to dma unmap the first entry, this is to restore to
         * the original state so that caller can free the memory in
         * error condition. Caller does not know if dma mapped or not*/
        if (pkt->addr[0].dma_mapped) {
                dma_unmap_single(&dd->pcidev->dev,
                       pkt->addr[0].addr,
                       pkt->addr[0].dma_length,
                       DMA_TO_DEVICE);
                pkt->addr[0].addr = 0;
                pkt->addr[0].dma_mapped = 0;
        }

done:
        return ret;
}

static int qib_user_sdma_init_payload(const struct qib_devdata *dd,
                                      struct qib_user_sdma_queue *pq,
                                      struct qib_user_sdma_pkt *pkt,
                                      const struct iovec *iov,
                                      unsigned long niov, int npages)
{
        int ret = 0;

        if (pkt->frag_size == pkt->bytes_togo &&
                        npages >= ARRAY_SIZE(pkt->addr))
                ret = qib_user_sdma_coalesce(dd, pq, pkt, iov, niov);
        else
                ret = qib_user_sdma_pin_pkt(dd, pq, pkt, iov, niov);

        return ret;
}

/* free a packet list -- return counter value of last packet */
static void qib_user_sdma_free_pkt_list(struct device *dev,
                                        struct qib_user_sdma_queue *pq,
                                        struct list_head *list)
{
        struct qib_user_sdma_pkt *pkt, *pkt_next;

        list_for_each_entry_safe(pkt, pkt_next, list, list) {
                int i;

                for (i = 0; i < pkt->naddr; i++)
                        qib_user_sdma_free_pkt_frag(dev, pq, pkt, i);

                if (pkt->largepkt)
                        kfree(pkt);
                else
                        kmem_cache_free(pq->pkt_slab, pkt);
        }
        INIT_LIST_HEAD(list);
}

/*
 * copy headers, coalesce etc -- pq->lock must be held
 *
 * we queue all the packets to list, returning the
 * number of bytes total.  list must be empty initially,
 * as, if there is an error we clean it...
 */
static int qib_user_sdma_queue_pkts(const struct qib_devdata *dd,
                                    struct qib_pportdata *ppd,
                                    struct qib_user_sdma_queue *pq,
                                    const struct iovec *iov,
                                    unsigned long niov,
                                    struct list_head *list,
                                    int *maxpkts, int *ndesc)
{
        unsigned long idx = 0;
        int ret = 0;
        int npkts = 0;
        __le32 *pbc;
        dma_addr_t dma_addr;
        struct qib_user_sdma_pkt *pkt = NULL;
        size_t len;
        size_t nw;
        u32 counter = pq->counter;
        u16 frag_size;

        while (idx < niov && npkts < *maxpkts) {
                const unsigned long addr = (unsigned long) iov[idx].iov_base;
                const unsigned long idx_save = idx;
                unsigned pktnw;
                unsigned pktnwc;
                int nfrags = 0;
                int npages = 0;
                int bytes_togo = 0;
                int tiddma = 0;
                int cfur;

                len = iov[idx].iov_len;
                nw = len >> 2;

                if (len < QIB_USER_SDMA_MIN_HEADER_LENGTH ||
                    len > PAGE_SIZE || len & 3 || addr & 3) {
                        ret = -EINVAL;
                        goto free_list;
                }

                pbc = qib_user_sdma_alloc_header(pq, len, &dma_addr);
                if (!pbc) {
                        ret = -ENOMEM;
                        goto free_list;
                }

                cfur = copy_from_user(pbc, iov[idx].iov_base, len);
                if (cfur) {
                        ret = -EFAULT;
                        goto free_pbc;
                }

                /*
                 * This assignment is a bit strange.  it's because the
                 * the pbc counts the number of 32 bit words in the full
                 * packet _except_ the first word of the pbc itself...
                 */
                pktnwc = nw - 1;

                /*
                 * pktnw computation yields the number of 32 bit words
                 * that the caller has indicated in the PBC.  note that
                 * this is one less than the total number of words that
                 * goes to the send DMA engine as the first 32 bit word
                 * of the PBC itself is not counted.  Armed with this count,
                 * we can verify that the packet is consistent with the
                 * iovec lengths.
                 */
                pktnw = le32_to_cpu(*pbc) & 0xFFFF;
                if (pktnw < pktnwc) {
                        ret = -EINVAL;
                        goto free_pbc;
                }

                idx++;
                while (pktnwc < pktnw && idx < niov) {
                        const size_t slen = iov[idx].iov_len;
                        const unsigned long faddr =
                                (unsigned long) iov[idx].iov_base;

                        if (slen & 3 || faddr & 3 || !slen) {
                                ret = -EINVAL;
                                goto free_pbc;
                        }

                        npages += qib_user_sdma_num_pages(&iov[idx]);

                        bytes_togo += slen;
                        pktnwc += slen >> 2;
                        idx++;
                        nfrags++;
                }

                if (pktnwc != pktnw) {
                        ret = -EINVAL;
                        goto free_pbc;
                }

                frag_size = ((le32_to_cpu(*pbc))>>16) & 0xFFFF;
                if (((frag_size ? frag_size : bytes_togo) + len) >
                                                ppd->ibmaxlen) {
                        ret = -EINVAL;
                        goto free_pbc;
                }

                if (frag_size) {
                        int pktsize, tidsmsize, n;

                        n = npages*((2*PAGE_SIZE/frag_size)+1);
                        pktsize = sizeof(*pkt) + sizeof(pkt->addr[0])*n;

                        /*
                         * Determine if this is tid-sdma or just sdma.
                         */
                        tiddma = (((le32_to_cpu(pbc[7])>>
                                QLOGIC_IB_I_TID_SHIFT)&
                                QLOGIC_IB_I_TID_MASK) !=
                                QLOGIC_IB_I_TID_MASK);

                        if (tiddma)
                                tidsmsize = iov[idx].iov_len;
                        else
                                tidsmsize = 0;

                        pkt = kmalloc(pktsize+tidsmsize, GFP_KERNEL);
                        if (!pkt) {
                                ret = -ENOMEM;
                                goto free_pbc;
                        }
                        pkt->largepkt = 1;
                        pkt->frag_size = frag_size;
                        pkt->addrlimit = n + ARRAY_SIZE(pkt->addr);

                        if (tiddma) {
                                char *tidsm = (char *)pkt + pktsize;
                                cfur = copy_from_user(tidsm,
                                        iov[idx].iov_base, tidsmsize);
                                if (cfur) {
                                        ret = -EFAULT;
                                        goto free_pkt;
                                }
                                pkt->tidsm =
                                        (struct qib_tid_session_member *)tidsm;
                                pkt->tidsmcount = tidsmsize/
                                        sizeof(struct qib_tid_session_member);
                                pkt->tidsmidx = 0;
                                idx++;
                        }

                        /*
                         * pbc 'fill1' field is borrowed to pass frag size,
                         * we need to clear it after picking frag size, the
                         * hardware requires this field to be zero.
                         */
                        *pbc = cpu_to_le32(le32_to_cpu(*pbc) & 0x0000FFFF);
                } else {
                        pkt = kmem_cache_alloc(pq->pkt_slab, GFP_KERNEL);
                        if (!pkt) {
                                ret = -ENOMEM;
                                goto free_pbc;
                        }
                        pkt->largepkt = 0;
                        pkt->frag_size = bytes_togo;
                        pkt->addrlimit = ARRAY_SIZE(pkt->addr);
                }
                pkt->bytes_togo = bytes_togo;
                pkt->payload_size = 0;
                pkt->counter = counter;
                pkt->tiddma = tiddma;

                /* setup the first header */
                qib_user_sdma_init_frag(pkt, 0, /* index */
                        0, len,         /* offset, len */
                        1, 0,           /* first last desc */
                        0, 0,           /* put page, dma mapped */
                        NULL, pbc,      /* struct page, virt addr */
                        dma_addr, len); /* dma addr, dma length */
                pkt->index = 0;
                pkt->naddr = 1;

                if (nfrags) {
                        ret = qib_user_sdma_init_payload(dd, pq, pkt,
                                                         iov + idx_save + 1,
                                                         nfrags, npages);
                        if (ret < 0)
                                goto free_pkt;
                } else {
                        /* since there is no payload, mark the
                         * header as the last desc. */
                        pkt->addr[0].last_desc = 1;

                        if (dma_addr == 0) {
                                /*
                                 * the header is not dma mapped yet.
                                 * it should be from kmalloc.
                                 */
                                dma_addr = dma_map_single(&dd->pcidev->dev,
                                        pbc, len, DMA_TO_DEVICE);
                                if (dma_mapping_error(&dd->pcidev->dev,
                                                                dma_addr)) {
                                        ret = -ENOMEM;
                                        goto free_pkt;
                                }
                                pkt->addr[0].addr = dma_addr;
                                pkt->addr[0].dma_mapped = 1;
                        }
                }

                counter++;
                npkts++;
                pkt->pq = pq;
                pkt->index = 0; /* reset index for push on hw */
                *ndesc += pkt->naddr;

                list_add_tail(&pkt->list, list);
        }

        *maxpkts = npkts;
        ret = idx;
        goto done;

free_pkt:
        if (pkt->largepkt)
                kfree(pkt);
        else
                kmem_cache_free(pq->pkt_slab, pkt);
free_pbc:
        if (dma_addr)
                dma_pool_free(pq->header_cache, pbc, dma_addr);
        else
                kfree(pbc);
free_list:
        qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, list);
done:
        return ret;
}

static void qib_user_sdma_set_complete_counter(struct qib_user_sdma_queue *pq,
                                               u32 c)
{
        pq->sent_counter = c;
}

/* try to clean out queue -- needs pq->lock */
static int qib_user_sdma_queue_clean(struct qib_pportdata *ppd,
                                     struct qib_user_sdma_queue *pq)
{
        struct qib_devdata *dd = ppd->dd;
        struct list_head free_list;
        struct qib_user_sdma_pkt *pkt;
        struct qib_user_sdma_pkt *pkt_prev;
        unsigned long flags;
        int ret = 0;

        if (!pq->num_sending)
                return 0;

        INIT_LIST_HEAD(&free_list);

        /*
         * We need this spin lock here because interrupt handler
         * might modify this list in qib_user_sdma_send_desc(), also
         * we can not get interrupted, otherwise it is a deadlock.
         */
        spin_lock_irqsave(&pq->sent_lock, flags);
        list_for_each_entry_safe(pkt, pkt_prev, &pq->sent, list) {
                s64 descd = ppd->sdma_descq_removed - pkt->added;

                if (descd < 0)
                        break;

                list_move_tail(&pkt->list, &free_list);

                /* one more packet cleaned */
                ret++;
                pq->num_sending--;

        }
        spin_unlock_irqrestore(&pq->sent_lock, flags);

        if (!list_empty(&free_list)) {
                u32 counter;

                pkt = list_entry(free_list.prev,
                                 struct qib_user_sdma_pkt, list);
                counter = pkt->counter;

                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
                qib_user_sdma_set_complete_counter(pq, counter);
        }

        return ret;
}

void qib_user_sdma_queue_destroy(struct qib_user_sdma_queue *pq)
{
        if (!pq)
                return;

        kmem_cache_destroy(pq->pkt_slab);
        dma_pool_destroy(pq->header_cache);
        kfree(pq);
}

/* clean descriptor queue, returns > 0 if some elements cleaned */
static int qib_user_sdma_hwqueue_clean(struct qib_pportdata *ppd)
{
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&ppd->sdma_lock, flags);
        ret = qib_sdma_make_progress(ppd);
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);

        return ret;
}

/* we're in close, drain packets so that we can cleanup successfully... */
void qib_user_sdma_queue_drain(struct qib_pportdata *ppd,
                               struct qib_user_sdma_queue *pq)
{
        struct qib_devdata *dd = ppd->dd;
        unsigned long flags;
        int i;

        if (!pq)
                return;

        for (i = 0; i < QIB_USER_SDMA_DRAIN_TIMEOUT; i++) {
                mutex_lock(&pq->lock);
                if (!pq->num_pending && !pq->num_sending) {
                        mutex_unlock(&pq->lock);
                        break;
                }
                qib_user_sdma_hwqueue_clean(ppd);
                qib_user_sdma_queue_clean(ppd, pq);
                mutex_unlock(&pq->lock);
                msleep(10);
        }

        if (pq->num_pending || pq->num_sending) {
                struct qib_user_sdma_pkt *pkt;
                struct qib_user_sdma_pkt *pkt_prev;
                struct list_head free_list;

                mutex_lock(&pq->lock);
                spin_lock_irqsave(&ppd->sdma_lock, flags);
                /*
                 * Since we hold sdma_lock, it is safe without sent_lock.
                 */
                if (pq->num_pending) {
                        list_for_each_entry_safe(pkt, pkt_prev,
                                        &ppd->sdma_userpending, list) {
                                if (pkt->pq == pq) {
                                        list_move_tail(&pkt->list, &pq->sent);
                                        pq->num_pending--;
                                        pq->num_sending++;
                                }
                        }
                }
                spin_unlock_irqrestore(&ppd->sdma_lock, flags);

                qib_dev_err(dd, "user sdma lists not empty: forcing!\n");
                INIT_LIST_HEAD(&free_list);
                list_splice_init(&pq->sent, &free_list);
                pq->num_sending = 0;
                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
                mutex_unlock(&pq->lock);
        }
}

static inline __le64 qib_sdma_make_desc0(u8 gen,
                                         u64 addr, u64 dwlen, u64 dwoffset)
{
        return cpu_to_le64(/* SDmaPhyAddr[31:0] */
                           ((addr & 0xfffffffcULL) << 32) |
                           /* SDmaGeneration[1:0] */
                           ((gen & 3ULL) << 30) |
                           /* SDmaDwordCount[10:0] */
                           ((dwlen & 0x7ffULL) << 16) |
                           /* SDmaBufOffset[12:2] */
                           (dwoffset & 0x7ffULL));
}

static inline __le64 qib_sdma_make_first_desc0(__le64 descq)
{
        return descq | cpu_to_le64(1ULL << 12);
}

static inline __le64 qib_sdma_make_last_desc0(__le64 descq)
{
                                              /* last */  /* dma head */
        return descq | cpu_to_le64(1ULL << 11 | 1ULL << 13);
}

static inline __le64 qib_sdma_make_desc1(u64 addr)
{
        /* SDmaPhyAddr[47:32] */
        return cpu_to_le64(addr >> 32);
}

static void qib_user_sdma_send_frag(struct qib_pportdata *ppd,
                                    struct qib_user_sdma_pkt *pkt, int idx,
                                    unsigned ofs, u16 tail, u8 gen)
{
        const u64 addr = (u64) pkt->addr[idx].addr +
                (u64) pkt->addr[idx].offset;
        const u64 dwlen = (u64) pkt->addr[idx].length / 4;
        __le64 *descqp;
        __le64 descq0;

        descqp = &ppd->sdma_descq[tail].qw[0];

        descq0 = qib_sdma_make_desc0(gen, addr, dwlen, ofs);
        if (pkt->addr[idx].first_desc)
                descq0 = qib_sdma_make_first_desc0(descq0);
        if (pkt->addr[idx].last_desc) {
                descq0 = qib_sdma_make_last_desc0(descq0);
                if (ppd->sdma_intrequest) {
                        descq0 |= cpu_to_le64(1ULL << 15);
                        ppd->sdma_intrequest = 0;
                }
        }

        descqp[0] = descq0;
        descqp[1] = qib_sdma_make_desc1(addr);
}

void qib_user_sdma_send_desc(struct qib_pportdata *ppd,
                                struct list_head *pktlist)
{
        struct qib_devdata *dd = ppd->dd;
        u16 nfree, nsent;
        u16 tail, tail_c;
        u8 gen, gen_c;

        nfree = qib_sdma_descq_freecnt(ppd);
        if (!nfree)
                return;

retry:
        nsent = 0;
        tail_c = tail = ppd->sdma_descq_tail;
        gen_c = gen = ppd->sdma_generation;
        while (!list_empty(pktlist)) {
                struct qib_user_sdma_pkt *pkt =
                        list_entry(pktlist->next, struct qib_user_sdma_pkt,
                                   list);
                int i, j, c = 0;
                unsigned ofs = 0;
                u16 dtail = tail;

                for (i = pkt->index; i < pkt->naddr && nfree; i++) {
                        qib_user_sdma_send_frag(ppd, pkt, i, ofs, tail, gen);
                        ofs += pkt->addr[i].length >> 2;

                        if (++tail == ppd->sdma_descq_cnt) {
                                tail = 0;
                                ++gen;
                                ppd->sdma_intrequest = 1;
                        } else if (tail == (ppd->sdma_descq_cnt>>1)) {
                                ppd->sdma_intrequest = 1;
                        }
                        nfree--;
                        if (pkt->addr[i].last_desc == 0)
                                continue;

                        /*
                         * If the packet is >= 2KB mtu equivalent, we
                         * have to use the large buffers, and have to
                         * mark each descriptor as part of a large
                         * buffer packet.
                         */
                        if (ofs > dd->piosize2kmax_dwords) {
                                for (j = pkt->index; j <= i; j++) {
                                        ppd->sdma_descq[dtail].qw[0] |=
                                                cpu_to_le64(1ULL << 14);
                                        if (++dtail == ppd->sdma_descq_cnt)
                                                dtail = 0;
                                }
                        }
                        c += i + 1 - pkt->index;
                        pkt->index = i + 1; /* index for next first */
                        tail_c = dtail = tail;
                        gen_c = gen;
                        ofs = 0;  /* reset for next packet */
                }

                ppd->sdma_descq_added += c;
                nsent += c;
                if (pkt->index == pkt->naddr) {
                        pkt->added = ppd->sdma_descq_added;
                        pkt->pq->added = pkt->added;
                        pkt->pq->num_pending--;
                        spin_lock(&pkt->pq->sent_lock);
                        pkt->pq->num_sending++;
                        list_move_tail(&pkt->list, &pkt->pq->sent);
                        spin_unlock(&pkt->pq->sent_lock);
                }
                if (!nfree || (nsent<<2) > ppd->sdma_descq_cnt)
                        break;
        }

        /* advance the tail on the chip if necessary */
        if (ppd->sdma_descq_tail != tail_c) {
                ppd->sdma_generation = gen_c;
                dd->f_sdma_update_tail(ppd, tail_c);
        }

        if (nfree && !list_empty(pktlist))
                goto retry;

        return;
}

/* pq->lock must be held, get packets on the wire... */
static int qib_user_sdma_push_pkts(struct qib_pportdata *ppd,
                                 struct qib_user_sdma_queue *pq,
                                 struct list_head *pktlist, int count)
{
        int ret = 0;
        unsigned long flags;

        if (unlikely(!(ppd->lflags & QIBL_LINKACTIVE)))
                return -ECOMM;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

        if (unlikely(!__qib_sdma_running(ppd))) {
                ret = -ECOMM;
                goto unlock;
        }

        pq->num_pending += count;
        list_splice_tail_init(pktlist, &ppd->sdma_userpending);
        qib_user_sdma_send_desc(ppd, &ppd->sdma_userpending);

unlock:
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);
        return ret;
}

int qib_user_sdma_writev(struct qib_ctxtdata *rcd,
                         struct qib_user_sdma_queue *pq,
                         const struct iovec *iov,
                         unsigned long dim)
{
        struct qib_devdata *dd = rcd->dd;
        struct qib_pportdata *ppd = rcd->ppd;
        int ret = 0;
        struct list_head list;
        int npkts = 0;

        INIT_LIST_HEAD(&list);

        mutex_lock(&pq->lock);

        /* why not -ECOMM like qib_user_sdma_push_pkts() below? */
        if (!qib_sdma_running(ppd))
                goto done_unlock;

        /* if I have packets not complete yet */
        if (pq->added > ppd->sdma_descq_removed)
                qib_user_sdma_hwqueue_clean(ppd);
        /* if I have complete packets to be freed */
        if (pq->num_sending)
                qib_user_sdma_queue_clean(ppd, pq);

        while (dim) {
                int mxp = 8;
                int ndesc = 0;

                ret = qib_user_sdma_queue_pkts(dd, ppd, pq,
                                iov, dim, &list, &mxp, &ndesc);
                if (ret < 0)
                        goto done_unlock;
                else {
                        dim -= ret;
                        iov += ret;
                }

                /* force packets onto the sdma hw queue... */
                if (!list_empty(&list)) {
                        /*
                         * Lazily clean hw queue.
                         */
                        if (qib_sdma_descq_freecnt(ppd) < ndesc) {
                                qib_user_sdma_hwqueue_clean(ppd);
                                if (pq->num_sending)
                                        qib_user_sdma_queue_clean(ppd, pq);
                        }

                        ret = qib_user_sdma_push_pkts(ppd, pq, &list, mxp);
                        if (ret < 0)
                                goto done_unlock;
                        else {
                                npkts += mxp;
                                pq->counter += mxp;
                        }
                }
        }

done_unlock:
        if (!list_empty(&list))
                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &list);
        mutex_unlock(&pq->lock);

        return (ret < 0) ? ret : npkts;
}

int qib_user_sdma_make_progress(struct qib_pportdata *ppd,
                                struct qib_user_sdma_queue *pq)
{
        int ret = 0;

        mutex_lock(&pq->lock);
        qib_user_sdma_hwqueue_clean(ppd);
        ret = qib_user_sdma_queue_clean(ppd, pq);
        mutex_unlock(&pq->lock);

        return ret;
}

u32 qib_user_sdma_complete_counter(const struct qib_user_sdma_queue *pq)
{
        return pq ? pq->sent_counter : 0;
}

u32 qib_user_sdma_inflight_counter(struct qib_user_sdma_queue *pq)
{
        return pq ? pq->counter : 0;
}