IB/ipath: drop requirement that PIO buffers be mmaped write-only

[linux-2.6] / drivers / infiniband / hw / ipath / ipath_file_ops.c

/*
 * Copyright (c) 2006 QLogic, Inc. All rights reserved.
 * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. 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/pci.h>
#include <linux/poll.h>
#include <linux/cdev.h>
#include <linux/swap.h>
#include <linux/vmalloc.h>
#include <asm/pgtable.h>

#include "ipath_kernel.h"
#include "ipath_layer.h"
#include "ipath_common.h"

static int ipath_open(struct inode *, struct file *);
static int ipath_close(struct inode *, struct file *);
static ssize_t ipath_write(struct file *, const char __user *, size_t,
                           loff_t *);
static unsigned int ipath_poll(struct file *, struct poll_table_struct *);
static int ipath_mmap(struct file *, struct vm_area_struct *);

static struct file_operations ipath_file_ops = {
        .owner = THIS_MODULE,
        .write = ipath_write,
        .open = ipath_open,
        .release = ipath_close,
        .poll = ipath_poll,
        .mmap = ipath_mmap
};

static int ipath_get_base_info(struct ipath_portdata *pd,
                               void __user *ubase, size_t ubase_size)
{
        int ret = 0;
        struct ipath_base_info *kinfo = NULL;
        struct ipath_devdata *dd = pd->port_dd;

        if (ubase_size < sizeof(*kinfo)) {
                ipath_cdbg(PROC,
                           "Base size %lu, need %lu (version mismatch?)\n",
                           (unsigned long) ubase_size,
                           (unsigned long) sizeof(*kinfo));
                ret = -EINVAL;
                goto bail;
        }

        kinfo = kzalloc(sizeof(*kinfo), GFP_KERNEL);
        if (kinfo == NULL) {
                ret = -ENOMEM;
                goto bail;
        }

        ret = dd->ipath_f_get_base_info(pd, kinfo);
        if (ret < 0)
                goto bail;

        kinfo->spi_rcvhdr_cnt = dd->ipath_rcvhdrcnt;
        kinfo->spi_rcvhdrent_size = dd->ipath_rcvhdrentsize;
        kinfo->spi_tidegrcnt = dd->ipath_rcvegrcnt;
        kinfo->spi_rcv_egrbufsize = dd->ipath_rcvegrbufsize;
        /*
         * have to mmap whole thing
         */
        kinfo->spi_rcv_egrbuftotlen =
                pd->port_rcvegrbuf_chunks * pd->port_rcvegrbuf_size;
        kinfo->spi_rcv_egrperchunk = pd->port_rcvegrbufs_perchunk;
        kinfo->spi_rcv_egrchunksize = kinfo->spi_rcv_egrbuftotlen /
                pd->port_rcvegrbuf_chunks;
        kinfo->spi_tidcnt = dd->ipath_rcvtidcnt;
        /*
         * for this use, may be ipath_cfgports summed over all chips that
         * are are configured and present
         */
        kinfo->spi_nports = dd->ipath_cfgports;
        /* unit (chip/board) our port is on */
        kinfo->spi_unit = dd->ipath_unit;
        /* for now, only a single page */
        kinfo->spi_tid_maxsize = PAGE_SIZE;

        /*
         * Doing this per port, and based on the skip value, etc.  This has
         * to be the actual buffer size, since the protocol code treats it
         * as an array.
         *
         * These have to be set to user addresses in the user code via mmap.
         * These values are used on return to user code for the mmap target
         * addresses only.  For 32 bit, same 44 bit address problem, so use
         * the physical address, not virtual.  Before 2.6.11, using the
         * page_address() macro worked, but in 2.6.11, even that returns the
         * full 64 bit address (upper bits all 1's).  So far, using the
         * physical addresses (or chip offsets, for chip mapping) works, but
         * no doubt some future kernel release will chang that, and we'll be
         * on to yet another method of dealing with this
         */
        kinfo->spi_rcvhdr_base = (u64) pd->port_rcvhdrq_phys;
        kinfo->spi_rcvhdr_tailaddr = (u64)pd->port_rcvhdrqtailaddr_phys;
        kinfo->spi_rcv_egrbufs = (u64) pd->port_rcvegr_phys;
        kinfo->spi_pioavailaddr = (u64) dd->ipath_pioavailregs_phys;
        kinfo->spi_status = (u64) kinfo->spi_pioavailaddr +
                (void *) dd->ipath_statusp -
                (void *) dd->ipath_pioavailregs_dma;
        kinfo->spi_piobufbase = (u64) pd->port_piobufs;
        kinfo->__spi_uregbase =
                dd->ipath_uregbase + dd->ipath_palign * pd->port_port;

        kinfo->spi_pioindex = dd->ipath_pbufsport * (pd->port_port - 1);
        kinfo->spi_piocnt = dd->ipath_pbufsport;
        kinfo->spi_pioalign = dd->ipath_palign;

        kinfo->spi_qpair = IPATH_KD_QP;
        kinfo->spi_piosize = dd->ipath_ibmaxlen;
        kinfo->spi_mtu = dd->ipath_ibmaxlen;    /* maxlen, not ibmtu */
        kinfo->spi_port = pd->port_port;
        kinfo->spi_sw_version = IPATH_KERN_SWVERSION;
        kinfo->spi_hw_version = dd->ipath_revision;

        if (copy_to_user(ubase, kinfo, sizeof(*kinfo)))
                ret = -EFAULT;

bail:
        kfree(kinfo);
        return ret;
}

/**
 * ipath_tid_update - update a port TID
 * @pd: the port
 * @ti: the TID information
 *
 * The new implementation as of Oct 2004 is that the driver assigns
 * the tid and returns it to the caller.   To make it easier to
 * catch bugs, and to reduce search time, we keep a cursor for
 * each port, walking the shadow tid array to find one that's not
 * in use.
 *
 * For now, if we can't allocate the full list, we fail, although
 * in the long run, we'll allocate as many as we can, and the
 * caller will deal with that by trying the remaining pages later.
 * That means that when we fail, we have to mark the tids as not in
 * use again, in our shadow copy.
 *
 * It's up to the caller to free the tids when they are done.
 * We'll unlock the pages as they free them.
 *
 * Also, right now we are locking one page at a time, but since
 * the intended use of this routine is for a single group of
 * virtually contiguous pages, that should change to improve
 * performance.
 */
static int ipath_tid_update(struct ipath_portdata *pd,
                            const struct ipath_tid_info *ti)
{
        int ret = 0, ntids;
        u32 tid, porttid, cnt, i, tidcnt;
        u16 *tidlist;
        struct ipath_devdata *dd = pd->port_dd;
        u64 physaddr;
        unsigned long vaddr;
        u64 __iomem *tidbase;
        unsigned long tidmap[8];
        struct page **pagep = NULL;

        if (!dd->ipath_pageshadow) {
                ret = -ENOMEM;
                goto done;
        }

        cnt = ti->tidcnt;
        if (!cnt) {
                ipath_dbg("After copyin, tidcnt 0, tidlist %llx\n",
                          (unsigned long long) ti->tidlist);
                /*
                 * Should we treat as success?  likely a bug
                 */
                ret = -EFAULT;
                goto done;
        }
        tidcnt = dd->ipath_rcvtidcnt;
        if (cnt >= tidcnt) {
                /* make sure it all fits in port_tid_pg_list */
                dev_info(&dd->pcidev->dev, "Process tried to allocate %u "
                         "TIDs, only trying max (%u)\n", cnt, tidcnt);
                cnt = tidcnt;
        }
        pagep = (struct page **)pd->port_tid_pg_list;
        tidlist = (u16 *) (&pagep[cnt]);

        memset(tidmap, 0, sizeof(tidmap));
        tid = pd->port_tidcursor;
        /* before decrement; chip actual # */
        porttid = pd->port_port * tidcnt;
        ntids = tidcnt;
        tidbase = (u64 __iomem *) (((char __iomem *) dd->ipath_kregbase) +
                                   dd->ipath_rcvtidbase +
                                   porttid * sizeof(*tidbase));

        ipath_cdbg(VERBOSE, "Port%u %u tids, cursor %u, tidbase %p\n",
                   pd->port_port, cnt, tid, tidbase);

        /* virtual address of first page in transfer */
        vaddr = ti->tidvaddr;
        if (!access_ok(VERIFY_WRITE, (void __user *) vaddr,
                       cnt * PAGE_SIZE)) {
                ipath_dbg("Fail vaddr %p, %u pages, !access_ok\n",
                          (void *)vaddr, cnt);
                ret = -EFAULT;
                goto done;
        }
        ret = ipath_get_user_pages(vaddr, cnt, pagep);
        if (ret) {
                if (ret == -EBUSY) {
                        ipath_dbg("Failed to lock addr %p, %u pages "
                                  "(already locked)\n",
                                  (void *) vaddr, cnt);
                        /*
                         * for now, continue, and see what happens but with
                         * the new implementation, this should never happen,
                         * unless perhaps the user has mpin'ed the pages
                         * themselves (something we need to test)
                         */
                        ret = 0;
                } else {
                        dev_info(&dd->pcidev->dev,
                                 "Failed to lock addr %p, %u pages: "
                                 "errno %d\n", (void *) vaddr, cnt, -ret);
                        goto done;
                }
        }
        for (i = 0; i < cnt; i++, vaddr += PAGE_SIZE) {
                for (; ntids--; tid++) {
                        if (tid == tidcnt)
                                tid = 0;
                        if (!dd->ipath_pageshadow[porttid + tid])
                                break;
                }
                if (ntids < 0) {
                        /*
                         * oops, wrapped all the way through their TIDs,
                         * and didn't have enough free; see comments at
                         * start of routine
                         */
                        ipath_dbg("Not enough free TIDs for %u pages "
                                  "(index %d), failing\n", cnt, i);
                        i--;    /* last tidlist[i] not filled in */
                        ret = -ENOMEM;
                        break;
                }
                tidlist[i] = tid;
                ipath_cdbg(VERBOSE, "Updating idx %u to TID %u, "
                           "vaddr %lx\n", i, tid, vaddr);
                /* we "know" system pages and TID pages are same size */
                dd->ipath_pageshadow[porttid + tid] = pagep[i];
                /*
                 * don't need atomic or it's overhead
                 */
                __set_bit(tid, tidmap);
                physaddr = page_to_phys(pagep[i]);
                ipath_stats.sps_pagelocks++;
                ipath_cdbg(VERBOSE,
                           "TID %u, vaddr %lx, physaddr %llx pgp %p\n",
                           tid, vaddr, (unsigned long long) physaddr,
                           pagep[i]);
                dd->ipath_f_put_tid(dd, &tidbase[tid], 1, physaddr);
                /*
                 * don't check this tid in ipath_portshadow, since we
                 * just filled it in; start with the next one.
                 */
                tid++;
        }

        if (ret) {
                u32 limit;
        cleanup:
                /* jump here if copy out of updated info failed... */
                ipath_dbg("After failure (ret=%d), undo %d of %d entries\n",
                          -ret, i, cnt);
                /* same code that's in ipath_free_tid() */
                limit = sizeof(tidmap) * BITS_PER_BYTE;
                if (limit > tidcnt)
                        /* just in case size changes in future */
                        limit = tidcnt;
                tid = find_first_bit((const unsigned long *)tidmap, limit);
                for (; tid < limit; tid++) {
                        if (!test_bit(tid, tidmap))
                                continue;
                        if (dd->ipath_pageshadow[porttid + tid]) {
                                ipath_cdbg(VERBOSE, "Freeing TID %u\n",
                                           tid);
                                dd->ipath_f_put_tid(dd, &tidbase[tid], 1,
                                                    dd->ipath_tidinvalid);
                                dd->ipath_pageshadow[porttid + tid] = NULL;
                                ipath_stats.sps_pageunlocks++;
                        }
                }
                ipath_release_user_pages(pagep, cnt);
        } else {
                /*
                 * Copy the updated array, with ipath_tid's filled in, back
                 * to user.  Since we did the copy in already, this "should
                 * never fail" If it does, we have to clean up...
                 */
                if (copy_to_user((void __user *)
                                 (unsigned long) ti->tidlist,
                                 tidlist, cnt * sizeof(*tidlist))) {
                        ret = -EFAULT;
                        goto cleanup;
                }
                if (copy_to_user((void __user *) (unsigned long) ti->tidmap,
                                 tidmap, sizeof tidmap)) {
                        ret = -EFAULT;
                        goto cleanup;
                }
                if (tid == tidcnt)
                        tid = 0;
                pd->port_tidcursor = tid;
        }

done:
        if (ret)
                ipath_dbg("Failed to map %u TID pages, failing with %d\n",
                          ti->tidcnt, -ret);
        return ret;
}

/**
 * ipath_tid_free - free a port TID
 * @pd: the port
 * @ti: the TID info
 *
 * right now we are unlocking one page at a time, but since
 * the intended use of this routine is for a single group of
 * virtually contiguous pages, that should change to improve
 * performance.  We check that the TID is in range for this port
 * but otherwise don't check validity; if user has an error and
 * frees the wrong tid, it's only their own data that can thereby
 * be corrupted.  We do check that the TID was in use, for sanity
 * We always use our idea of the saved address, not the address that
 * they pass in to us.
 */

static int ipath_tid_free(struct ipath_portdata *pd,
                          const struct ipath_tid_info *ti)
{
        int ret = 0;
        u32 tid, porttid, cnt, limit, tidcnt;
        struct ipath_devdata *dd = pd->port_dd;
        u64 __iomem *tidbase;
        unsigned long tidmap[8];

        if (!dd->ipath_pageshadow) {
                ret = -ENOMEM;
                goto done;
        }

        if (copy_from_user(tidmap, (void __user *)(unsigned long)ti->tidmap,
                           sizeof tidmap)) {
                ret = -EFAULT;
                goto done;
        }

        porttid = pd->port_port * dd->ipath_rcvtidcnt;
        tidbase = (u64 __iomem *) ((char __iomem *)(dd->ipath_kregbase) +
                                   dd->ipath_rcvtidbase +
                                   porttid * sizeof(*tidbase));

        tidcnt = dd->ipath_rcvtidcnt;
        limit = sizeof(tidmap) * BITS_PER_BYTE;
        if (limit > tidcnt)
                /* just in case size changes in future */
                limit = tidcnt;
        tid = find_first_bit(tidmap, limit);
        ipath_cdbg(VERBOSE, "Port%u free %u tids; first bit (max=%d) "
                   "set is %d, porttid %u\n", pd->port_port, ti->tidcnt,
                   limit, tid, porttid);
        for (cnt = 0; tid < limit; tid++) {
                /*
                 * small optimization; if we detect a run of 3 or so without
                 * any set, use find_first_bit again.  That's mainly to
                 * accelerate the case where we wrapped, so we have some at
                 * the beginning, and some at the end, and a big gap
                 * in the middle.
                 */
                if (!test_bit(tid, tidmap))
                        continue;
                cnt++;
                if (dd->ipath_pageshadow[porttid + tid]) {
                        ipath_cdbg(VERBOSE, "PID %u freeing TID %u\n",
                                   pd->port_pid, tid);
                        dd->ipath_f_put_tid(dd, &tidbase[tid], 1,
                                            dd->ipath_tidinvalid);
                        ipath_release_user_pages(
                                &dd->ipath_pageshadow[porttid + tid], 1);
                        dd->ipath_pageshadow[porttid + tid] = NULL;
                        ipath_stats.sps_pageunlocks++;
                } else
                        ipath_dbg("Unused tid %u, ignoring\n", tid);
        }
        if (cnt != ti->tidcnt)
                ipath_dbg("passed in tidcnt %d, only %d bits set in map\n",
                          ti->tidcnt, cnt);
done:
        if (ret)
                ipath_dbg("Failed to unmap %u TID pages, failing with %d\n",
                          ti->tidcnt, -ret);
        return ret;
}

/**
 * ipath_set_part_key - set a partition key
 * @pd: the port
 * @key: the key
 *
 * We can have up to 4 active at a time (other than the default, which is
 * always allowed).  This is somewhat tricky, since multiple ports may set
 * the same key, so we reference count them, and clean up at exit.  All 4
 * partition keys are packed into a single infinipath register.  It's an
 * error for a process to set the same pkey multiple times.  We provide no
 * mechanism to de-allocate a pkey at this time, we may eventually need to
 * do that.  I've used the atomic operations, and no locking, and only make
 * a single pass through what's available.  This should be more than
 * adequate for some time. I'll think about spinlocks or the like if and as
 * it's necessary.
 */
static int ipath_set_part_key(struct ipath_portdata *pd, u16 key)
{
        struct ipath_devdata *dd = pd->port_dd;
        int i, any = 0, pidx = -1;
        u16 lkey = key & 0x7FFF;
        int ret;

        if (lkey == (IPATH_DEFAULT_P_KEY & 0x7FFF)) {
                /* nothing to do; this key always valid */
                ret = 0;
                goto bail;
        }

        ipath_cdbg(VERBOSE, "p%u try to set pkey %hx, current keys "
                   "%hx:%x %hx:%x %hx:%x %hx:%x\n",
                   pd->port_port, key, dd->ipath_pkeys[0],
                   atomic_read(&dd->ipath_pkeyrefs[0]), dd->ipath_pkeys[1],
                   atomic_read(&dd->ipath_pkeyrefs[1]), dd->ipath_pkeys[2],
                   atomic_read(&dd->ipath_pkeyrefs[2]), dd->ipath_pkeys[3],
                   atomic_read(&dd->ipath_pkeyrefs[3]));

        if (!lkey) {
                ipath_cdbg(PROC, "p%u tries to set key 0, not allowed\n",
                           pd->port_port);
                ret = -EINVAL;
                goto bail;
        }

        /*
         * Set the full membership bit, because it has to be
         * set in the register or the packet, and it seems
         * cleaner to set in the register than to force all
         * callers to set it. (see bug 4331)
         */
        key |= 0x8000;

        for (i = 0; i < ARRAY_SIZE(pd->port_pkeys); i++) {
                if (!pd->port_pkeys[i] && pidx == -1)
                        pidx = i;
                if (pd->port_pkeys[i] == key) {
                        ipath_cdbg(VERBOSE, "p%u tries to set same pkey "
                                   "(%x) more than once\n",
                                   pd->port_port, key);
                        ret = -EEXIST;
                        goto bail;
                }
        }
        if (pidx == -1) {
                ipath_dbg("All pkeys for port %u already in use, "
                          "can't set %x\n", pd->port_port, key);
                ret = -EBUSY;
                goto bail;
        }
        for (any = i = 0; i < ARRAY_SIZE(dd->ipath_pkeys); i++) {
                if (!dd->ipath_pkeys[i]) {
                        any++;
                        continue;
                }
                if (dd->ipath_pkeys[i] == key) {
                        atomic_t *pkrefs = &dd->ipath_pkeyrefs[i];

                        if (atomic_inc_return(pkrefs) > 1) {
                                pd->port_pkeys[pidx] = key;
                                ipath_cdbg(VERBOSE, "p%u set key %x "
                                           "matches #%d, count now %d\n",
                                           pd->port_port, key, i,
                                           atomic_read(pkrefs));
                                ret = 0;
                                goto bail;
                        } else {
                                /*
                                 * lost race, decrement count, catch below
                                 */
                                atomic_dec(pkrefs);
                                ipath_cdbg(VERBOSE, "Lost race, count was "
                                           "0, after dec, it's %d\n",
                                           atomic_read(pkrefs));
                                any++;
                        }
                }
                if ((dd->ipath_pkeys[i] & 0x7FFF) == lkey) {
                        /*
                         * It makes no sense to have both the limited and
                         * full membership PKEY set at the same time since
                         * the unlimited one will disable the limited one.
                         */
                        ret = -EEXIST;
                        goto bail;
                }
        }
        if (!any) {
                ipath_dbg("port %u, all pkeys already in use, "
                          "can't set %x\n", pd->port_port, key);
                ret = -EBUSY;
                goto bail;
        }
        for (any = i = 0; i < ARRAY_SIZE(dd->ipath_pkeys); i++) {
                if (!dd->ipath_pkeys[i] &&
                    atomic_inc_return(&dd->ipath_pkeyrefs[i]) == 1) {
                        u64 pkey;

                        /* for ipathstats, etc. */
                        ipath_stats.sps_pkeys[i] = lkey;
                        pd->port_pkeys[pidx] = dd->ipath_pkeys[i] = key;
                        pkey =
                                (u64) dd->ipath_pkeys[0] |
                                ((u64) dd->ipath_pkeys[1] << 16) |
                                ((u64) dd->ipath_pkeys[2] << 32) |
                                ((u64) dd->ipath_pkeys[3] << 48);
                        ipath_cdbg(PROC, "p%u set key %x in #%d, "
                                   "portidx %d, new pkey reg %llx\n",
                                   pd->port_port, key, i, pidx,
                                   (unsigned long long) pkey);
                        ipath_write_kreg(
                                dd, dd->ipath_kregs->kr_partitionkey, pkey);

                        ret = 0;
                        goto bail;
                }
        }
        ipath_dbg("port %u, all pkeys already in use 2nd pass, "
                  "can't set %x\n", pd->port_port, key);
        ret = -EBUSY;

bail:
        return ret;
}

/**
 * ipath_manage_rcvq - manage a port's receive queue
 * @pd: the port
 * @start_stop: action to carry out
 *
 * start_stop == 0 disables receive on the port, for use in queue
 * overflow conditions.  start_stop==1 re-enables, to be used to
 * re-init the software copy of the head register
 */
static int ipath_manage_rcvq(struct ipath_portdata *pd, int start_stop)
{
        struct ipath_devdata *dd = pd->port_dd;
        u64 tval;

        ipath_cdbg(PROC, "%sabling rcv for unit %u port %u\n",
                   start_stop ? "en" : "dis", dd->ipath_unit,
                   pd->port_port);
        /* atomically clear receive enable port. */
        if (start_stop) {
                /*
                 * On enable, force in-memory copy of the tail register to
                 * 0, so that protocol code doesn't have to worry about
                 * whether or not the chip has yet updated the in-memory
                 * copy or not on return from the system call. The chip
                 * always resets it's tail register back to 0 on a
                 * transition from disabled to enabled.  This could cause a
                 * problem if software was broken, and did the enable w/o
                 * the disable, but eventually the in-memory copy will be
                 * updated and correct itself, even in the face of software
                 * bugs.
                 */
                *pd->port_rcvhdrtail_kvaddr = 0;
                set_bit(INFINIPATH_R_PORTENABLE_SHIFT + pd->port_port,
                        &dd->ipath_rcvctrl);
        } else
                clear_bit(INFINIPATH_R_PORTENABLE_SHIFT + pd->port_port,
                          &dd->ipath_rcvctrl);
        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);
        /* now be sure chip saw it before we return */
        tval = ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
        if (start_stop) {
                /*
                 * And try to be sure that tail reg update has happened too.
                 * This should in theory interlock with the RXE changes to
                 * the tail register.  Don't assign it to the tail register
                 * in memory copy, since we could overwrite an update by the
                 * chip if we did.
                 */
                tval = ipath_read_ureg32(dd, ur_rcvhdrtail, pd->port_port);
        }
        /* always; new head should be equal to new tail; see above */
        return 0;
}

static void ipath_clean_part_key(struct ipath_portdata *pd,
                                 struct ipath_devdata *dd)
{
        int i, j, pchanged = 0;
        u64 oldpkey;

        /* for debugging only */
        oldpkey = (u64) dd->ipath_pkeys[0] |
                ((u64) dd->ipath_pkeys[1] << 16) |
                ((u64) dd->ipath_pkeys[2] << 32) |
                ((u64) dd->ipath_pkeys[3] << 48);

        for (i = 0; i < ARRAY_SIZE(pd->port_pkeys); i++) {
                if (!pd->port_pkeys[i])
                        continue;
                ipath_cdbg(VERBOSE, "look for key[%d] %hx in pkeys\n", i,
                           pd->port_pkeys[i]);
                for (j = 0; j < ARRAY_SIZE(dd->ipath_pkeys); j++) {
                        /* check for match independent of the global bit */
                        if ((dd->ipath_pkeys[j] & 0x7fff) !=
                            (pd->port_pkeys[i] & 0x7fff))
                                continue;
                        if (atomic_dec_and_test(&dd->ipath_pkeyrefs[j])) {
                                ipath_cdbg(VERBOSE, "p%u clear key "
                                           "%x matches #%d\n",
                                           pd->port_port,
                                           pd->port_pkeys[i], j);
                                ipath_stats.sps_pkeys[j] =
                                        dd->ipath_pkeys[j] = 0;
                                pchanged++;
                        }
                        else ipath_cdbg(
                                VERBOSE, "p%u key %x matches #%d, "
                                "but ref still %d\n", pd->port_port,
                                pd->port_pkeys[i], j,
                                atomic_read(&dd->ipath_pkeyrefs[j]));
                        break;
                }
                pd->port_pkeys[i] = 0;
        }
        if (pchanged) {
                u64 pkey = (u64) dd->ipath_pkeys[0] |
                        ((u64) dd->ipath_pkeys[1] << 16) |
                        ((u64) dd->ipath_pkeys[2] << 32) |
                        ((u64) dd->ipath_pkeys[3] << 48);
                ipath_cdbg(VERBOSE, "p%u old pkey reg %llx, "
                           "new pkey reg %llx\n", pd->port_port,
                           (unsigned long long) oldpkey,
                           (unsigned long long) pkey);
                ipath_write_kreg(dd, dd->ipath_kregs->kr_partitionkey,
                                 pkey);
        }
}

/**
 * ipath_create_user_egr - allocate eager TID buffers
 * @pd: the port to allocate TID buffers for
 *
 * This routine is now quite different for user and kernel, because
 * the kernel uses skb's, for the accelerated network performance
 * This is the user port version
 *
 * Allocate the eager TID buffers and program them into infinipath
 * They are no longer completely contiguous, we do multiple allocation
 * calls.
 */
static int ipath_create_user_egr(struct ipath_portdata *pd)
{
        struct ipath_devdata *dd = pd->port_dd;
        unsigned e, egrcnt, alloced, egrperchunk, chunk, egrsize, egroff;
        size_t size;
        int ret;
        gfp_t gfp_flags;

        /*
         * GFP_USER, but without GFP_FS, so buffer cache can be
         * coalesced (we hope); otherwise, even at order 4,
         * heavy filesystem activity makes these fail, and we can
         * use compound pages.
         */
        gfp_flags = __GFP_WAIT | __GFP_IO | __GFP_COMP;

        egrcnt = dd->ipath_rcvegrcnt;
        /* TID number offset for this port */
        egroff = pd->port_port * egrcnt;
        egrsize = dd->ipath_rcvegrbufsize;
        ipath_cdbg(VERBOSE, "Allocating %d egr buffers, at egrtid "
                   "offset %x, egrsize %u\n", egrcnt, egroff, egrsize);

        /*
         * to avoid wasting a lot of memory, we allocate 32KB chunks of
         * physically contiguous memory, advance through it until used up
         * and then allocate more.  Of course, we need memory to store those
         * extra pointers, now.  Started out with 256KB, but under heavy
         * memory pressure (creating large files and then copying them over
         * NFS while doing lots of MPI jobs), we hit some allocation
         * failures, even though we can sleep...  (2.6.10) Still get
         * failures at 64K.  32K is the lowest we can go without wasting
         * additional memory.
         */
        size = 0x8000;
        alloced = ALIGN(egrsize * egrcnt, size);
        egrperchunk = size / egrsize;
        chunk = (egrcnt + egrperchunk - 1) / egrperchunk;
        pd->port_rcvegrbuf_chunks = chunk;
        pd->port_rcvegrbufs_perchunk = egrperchunk;
        pd->port_rcvegrbuf_size = size;
        pd->port_rcvegrbuf = vmalloc(chunk * sizeof(pd->port_rcvegrbuf[0]));
        if (!pd->port_rcvegrbuf) {
                ret = -ENOMEM;
                goto bail;
        }
        pd->port_rcvegrbuf_phys =
                vmalloc(chunk * sizeof(pd->port_rcvegrbuf_phys[0]));
        if (!pd->port_rcvegrbuf_phys) {
                ret = -ENOMEM;
                goto bail_rcvegrbuf;
        }
        for (e = 0; e < pd->port_rcvegrbuf_chunks; e++) {

                pd->port_rcvegrbuf[e] = dma_alloc_coherent(
                        &dd->pcidev->dev, size, &pd->port_rcvegrbuf_phys[e],
                        gfp_flags);

                if (!pd->port_rcvegrbuf[e]) {
                        ret = -ENOMEM;
                        goto bail_rcvegrbuf_phys;
                }
        }

        pd->port_rcvegr_phys = pd->port_rcvegrbuf_phys[0];

        for (e = chunk = 0; chunk < pd->port_rcvegrbuf_chunks; chunk++) {
                dma_addr_t pa = pd->port_rcvegrbuf_phys[chunk];
                unsigned i;

                for (i = 0; e < egrcnt && i < egrperchunk; e++, i++) {
                        dd->ipath_f_put_tid(dd, e + egroff +
                                            (u64 __iomem *)
                                            ((char __iomem *)
                                             dd->ipath_kregbase +
                                             dd->ipath_rcvegrbase), 0, pa);
                        pa += egrsize;
                }
                cond_resched(); /* don't hog the cpu */
        }

        ret = 0;
        goto bail;

bail_rcvegrbuf_phys:
        for (e = 0; e < pd->port_rcvegrbuf_chunks &&
                pd->port_rcvegrbuf[e]; e++) {
                dma_free_coherent(&dd->pcidev->dev, size,
                                  pd->port_rcvegrbuf[e],
                                  pd->port_rcvegrbuf_phys[e]);

        }
        vfree(pd->port_rcvegrbuf_phys);
        pd->port_rcvegrbuf_phys = NULL;
bail_rcvegrbuf:
        vfree(pd->port_rcvegrbuf);
        pd->port_rcvegrbuf = NULL;
bail:
        return ret;
}

static int ipath_do_user_init(struct ipath_portdata *pd,
                              const struct ipath_user_info *uinfo)
{
        int ret = 0;
        struct ipath_devdata *dd = pd->port_dd;
        u32 head32;

        /* for now, if major version is different, bail */
        if ((uinfo->spu_userversion >> 16) != IPATH_USER_SWMAJOR) {
                dev_info(&dd->pcidev->dev,
                         "User major version %d not same as driver "
                         "major %d\n", uinfo->spu_userversion >> 16,
                         IPATH_USER_SWMAJOR);
                ret = -ENODEV;
                goto done;
        }

        if ((uinfo->spu_userversion & 0xffff) != IPATH_USER_SWMINOR)
                ipath_dbg("User minor version %d not same as driver "
                          "minor %d\n", uinfo->spu_userversion & 0xffff,
                          IPATH_USER_SWMINOR);

        if (uinfo->spu_rcvhdrsize) {
                ret = ipath_setrcvhdrsize(dd, uinfo->spu_rcvhdrsize);
                if (ret)
                        goto done;
        }

        /* for now we do nothing with rcvhdrcnt: uinfo->spu_rcvhdrcnt */

        /* for right now, kernel piobufs are at end, so port 1 is at 0 */
        pd->port_piobufs = dd->ipath_piobufbase +
                dd->ipath_pbufsport * (pd->port_port -
                                       1) * dd->ipath_palign;
        ipath_cdbg(VERBOSE, "Set base of piobufs for port %u to 0x%x\n",
                   pd->port_port, pd->port_piobufs);

        /*
         * Now allocate the rcvhdr Q and eager TIDs; skip the TID
         * array for time being.  If pd->port_port > chip-supported,
         * we need to do extra stuff here to handle by handling overflow
         * through port 0, someday
         */
        ret = ipath_create_rcvhdrq(dd, pd);
        if (!ret)
                ret = ipath_create_user_egr(pd);
        if (ret)
                goto done;

        /*
         * set the eager head register for this port to the current values
         * of the tail pointers, since we don't know if they were
         * updated on last use of the port.
         */
        head32 = ipath_read_ureg32(dd, ur_rcvegrindextail, pd->port_port);
        ipath_write_ureg(dd, ur_rcvegrindexhead, head32, pd->port_port);
        dd->ipath_lastegrheads[pd->port_port] = -1;
        dd->ipath_lastrcvhdrqtails[pd->port_port] = -1;
        ipath_cdbg(VERBOSE, "Wrote port%d egrhead %x from tail regs\n",
                pd->port_port, head32);
        pd->port_tidcursor = 0; /* start at beginning after open */
        /*
         * now enable the port; the tail registers will be written to memory
         * by the chip as soon as it sees the write to
         * dd->ipath_kregs->kr_rcvctrl.  The update only happens on
         * transition from 0 to 1, so clear it first, then set it as part of
         * enabling the port.  This will (very briefly) affect any other
         * open ports, but it shouldn't be long enough to be an issue.
         * We explictly set the in-memory copy to 0 beforehand, so we don't
         * have to wait to be sure the DMA update has happened.
         */
        *pd->port_rcvhdrtail_kvaddr = 0ULL;
        set_bit(INFINIPATH_R_PORTENABLE_SHIFT + pd->port_port,
                &dd->ipath_rcvctrl);
        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl & ~INFINIPATH_R_TAILUPD);
        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);
done:
        return ret;
}


/* common code for the mappings on dma_alloc_coherent mem */
static int ipath_mmap_mem(struct vm_area_struct *vma,
                             struct ipath_portdata *pd, unsigned len,
                             int write_ok, dma_addr_t addr, char *what)
{
        struct ipath_devdata *dd = pd->port_dd;
        unsigned pfn = (unsigned long)addr >> PAGE_SHIFT;
        int ret;

        if ((vma->vm_end - vma->vm_start) > len) {
                dev_info(&dd->pcidev->dev,
                         "FAIL on %s: len %lx > %x\n", what,
                         vma->vm_end - vma->vm_start, len);
                ret = -EFAULT;
                goto bail;
        }

        if (!write_ok) {
                if (vma->vm_flags & VM_WRITE) {
                        dev_info(&dd->pcidev->dev,
                                 "%s must be mapped readonly\n", what);
                        ret = -EPERM;
                        goto bail;
                }

                /* don't allow them to later change with mprotect */
                vma->vm_flags &= ~VM_MAYWRITE;
        }

        ret = remap_pfn_range(vma, vma->vm_start, pfn,
                              len, vma->vm_page_prot);
        if (ret)
                dev_info(&dd->pcidev->dev,
                         "%s port%u mmap of %lx, %x bytes r%c failed: %d\n",
                         what, pd->port_port, (unsigned long)addr, len,
                         write_ok?'w':'o', ret);
        else
                ipath_cdbg(VERBOSE, "%s port%u mmaped %lx, %x bytes r%c\n",
                        what, pd->port_port, (unsigned long)addr, len,
                         write_ok?'w':'o');
bail:
        return ret;
}

static int mmap_ureg(struct vm_area_struct *vma, struct ipath_devdata *dd,
                     u64 ureg)
{
        unsigned long phys;
        int ret;

        /*
         * This is real hardware, so use io_remap.  This is the mechanism
         * for the user process to update the head registers for their port
         * in the chip.
         */
        if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
                dev_info(&dd->pcidev->dev, "FAIL mmap userreg: reqlen "
                         "%lx > PAGE\n", vma->vm_end - vma->vm_start);
                ret = -EFAULT;
        } else {
                phys = dd->ipath_physaddr + ureg;
                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

                vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;
                ret = io_remap_pfn_range(vma, vma->vm_start,
                                         phys >> PAGE_SHIFT,
                                         vma->vm_end - vma->vm_start,
                                         vma->vm_page_prot);
        }
        return ret;
}

static int mmap_piobufs(struct vm_area_struct *vma,
                        struct ipath_devdata *dd,
                        struct ipath_portdata *pd)
{
        unsigned long phys;
        int ret;

        /*
         * When we map the PIO buffers in the chip, we want to map them as
         * writeonly, no read possible.   This prevents access to previous
         * process data, and catches users who might try to read the i/o
         * space due to a bug.
         */
        if ((vma->vm_end - vma->vm_start) >
            (dd->ipath_pbufsport * dd->ipath_palign)) {
                dev_info(&dd->pcidev->dev, "FAIL mmap piobufs: "
                         "reqlen %lx > PAGE\n",
                         vma->vm_end - vma->vm_start);
                ret = -EFAULT;
                goto bail;
        }

        phys = dd->ipath_physaddr + pd->port_piobufs;

        /*
         * Don't mark this as non-cached, or we don't get the
         * write combining behavior we want on the PIO buffers!
         */

#if defined(__powerpc__)
        /* There isn't a generic way to specify writethrough mappings */
        pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
        pgprot_val(vma->vm_page_prot) |= _PAGE_WRITETHRU;
        pgprot_val(vma->vm_page_prot) &= ~_PAGE_GUARDED;
#endif

        /*
         * don't allow them to later change to readable with mprotect (for when
         * not initially mapped readable, as is normally the case)
         */
        vma->vm_flags &= ~VM_MAYREAD;
        vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;

        ret = io_remap_pfn_range(vma, vma->vm_start, phys >> PAGE_SHIFT,
                                 vma->vm_end - vma->vm_start,
                                 vma->vm_page_prot);
bail:
        return ret;
}

static int mmap_rcvegrbufs(struct vm_area_struct *vma,
                           struct ipath_portdata *pd)
{
        struct ipath_devdata *dd = pd->port_dd;
        unsigned long start, size;
        size_t total_size, i;
        dma_addr_t *phys;
        int ret;

        size = pd->port_rcvegrbuf_size;
        total_size = pd->port_rcvegrbuf_chunks * size;
        if ((vma->vm_end - vma->vm_start) > total_size) {
                dev_info(&dd->pcidev->dev, "FAIL on egr bufs: "
                         "reqlen %lx > actual %lx\n",
                         vma->vm_end - vma->vm_start,
                         (unsigned long) total_size);
                ret = -EFAULT;
                goto bail;
        }

        if (vma->vm_flags & VM_WRITE) {
                dev_info(&dd->pcidev->dev, "Can't map eager buffers as "
                         "writable (flags=%lx)\n", vma->vm_flags);
                ret = -EPERM;
                goto bail;
        }
        /* don't allow them to later change to writeable with mprotect */
        vma->vm_flags &= ~VM_MAYWRITE;

        start = vma->vm_start;
        phys = pd->port_rcvegrbuf_phys;

        for (i = 0; i < pd->port_rcvegrbuf_chunks; i++, start += size) {
                ret = remap_pfn_range(vma, start, phys[i] >> PAGE_SHIFT,
                                      size, vma->vm_page_prot);
                if (ret < 0)
                        goto bail;
        }
        ret = 0;

bail:
        return ret;
}

/**
 * ipath_mmap - mmap various structures into user space
 * @fp: the file pointer
 * @vma: the VM area
 *
 * We use this to have a shared buffer between the kernel and the user code
 * for the rcvhdr queue, egr buffers, and the per-port user regs and pio
 * buffers in the chip.  We have the open and close entries so we can bump
 * the ref count and keep the driver from being unloaded while still mapped.
 */
static int ipath_mmap(struct file *fp, struct vm_area_struct *vma)
{
        struct ipath_portdata *pd;
        struct ipath_devdata *dd;
        u64 pgaddr, ureg;
        int ret;

        pd = port_fp(fp);
        dd = pd->port_dd;

        /*
         * This is the ipath_do_user_init() code, mapping the shared buffers
         * into the user process. The address referred to by vm_pgoff is the
         * virtual, not physical, address; we only do one mmap for each
         * space mapped.
         */
        pgaddr = vma->vm_pgoff << PAGE_SHIFT;

        /*
         * Must fit in 40 bits for our hardware; some checked elsewhere,
         * but we'll be paranoid.  Check for 0 is mostly in case one of the
         * allocations failed, but user called mmap anyway.   We want to catch
         * that before it can match.
         */
        if (!pgaddr || pgaddr >= (1ULL<<40))  {
                ipath_dev_err(dd, "Bad phys addr %llx, start %lx, end %lx\n",
                        (unsigned long long)pgaddr, vma->vm_start, vma->vm_end);
                return -EINVAL;
        }

        /* just the offset of the port user registers, not physical addr */
        ureg = dd->ipath_uregbase + dd->ipath_palign * pd->port_port;

        ipath_cdbg(MM, "ushare: pgaddr %llx vm_start=%lx, vmlen %lx\n",
                   (unsigned long long) pgaddr, vma->vm_start,
                   vma->vm_end - vma->vm_start);

        if (vma->vm_start & (PAGE_SIZE-1)) {
                ipath_dev_err(dd,
                        "vm_start not aligned: %lx, end=%lx phys %lx\n",
                        vma->vm_start, vma->vm_end, (unsigned long)pgaddr);
                ret = -EINVAL;
        }
        else if (pgaddr == ureg)
                ret = mmap_ureg(vma, dd, ureg);
        else if (pgaddr == pd->port_piobufs)
                ret = mmap_piobufs(vma, dd, pd);
        else if (pgaddr == (u64) pd->port_rcvegr_phys)
                ret = mmap_rcvegrbufs(vma, pd);
        else if (pgaddr == (u64) pd->port_rcvhdrq_phys) {
                /*
                 * The rcvhdrq itself; readonly except on HT-400 (so have
                 * to allow writable mapping), multiple pages, contiguous
                 * from an i/o perspective.
                 */
                unsigned total_size =
                        ALIGN(dd->ipath_rcvhdrcnt * dd->ipath_rcvhdrentsize
                           * sizeof(u32), PAGE_SIZE);
                ret = ipath_mmap_mem(vma, pd, total_size, 1,
                                     pd->port_rcvhdrq_phys,
                                     "rcvhdrq");
        }
        else if (pgaddr == (u64)pd->port_rcvhdrqtailaddr_phys)
                /* in-memory copy of rcvhdrq tail register */
                ret = ipath_mmap_mem(vma, pd, PAGE_SIZE, 0,
                                     pd->port_rcvhdrqtailaddr_phys,
                                     "rcvhdrq tail");
        else if (pgaddr == dd->ipath_pioavailregs_phys)
                /* in-memory copy of pioavail registers */
                ret = ipath_mmap_mem(vma, pd, PAGE_SIZE, 0,
                                     dd->ipath_pioavailregs_phys,
                                     "pioavail registers");
        else
                ret = -EINVAL;

        vma->vm_private_data = NULL;

        if (ret < 0)
                dev_info(&dd->pcidev->dev,
                         "Failure %d on addr %lx, off %lx\n",
                         -ret, vma->vm_start, vma->vm_pgoff);

        return ret;
}

static unsigned int ipath_poll(struct file *fp,
                               struct poll_table_struct *pt)
{
        struct ipath_portdata *pd;
        u32 head, tail;
        int bit;
        struct ipath_devdata *dd;

        pd = port_fp(fp);
        dd = pd->port_dd;

        bit = pd->port_port + INFINIPATH_R_INTRAVAIL_SHIFT;
        set_bit(bit, &dd->ipath_rcvctrl);

        /*
         * Before blocking, make sure that head is still == tail,
         * reading from the chip, so we can be sure the interrupt
         * enable has made it to the chip.  If not equal, disable
         * interrupt again and return immediately.  This avoids races,
         * and the overhead of the chip read doesn't matter much at
         * this point, since we are waiting for something anyway.
         */

        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);

        head = ipath_read_ureg32(dd, ur_rcvhdrhead, pd->port_port);
        tail = ipath_read_ureg32(dd, ur_rcvhdrtail, pd->port_port);

        if (tail == head) {
                set_bit(IPATH_PORT_WAITING_RCV, &pd->port_flag);
                if(dd->ipath_rhdrhead_intr_off) /* arm rcv interrupt */
                        (void)ipath_write_ureg(dd, ur_rcvhdrhead,
                                               dd->ipath_rhdrhead_intr_off
                                               | head, pd->port_port);
                poll_wait(fp, &pd->port_wait, pt);

                if (test_bit(IPATH_PORT_WAITING_RCV, &pd->port_flag)) {
                        /* timed out, no packets received */
                        clear_bit(IPATH_PORT_WAITING_RCV, &pd->port_flag);
                        pd->port_rcvwait_to++;
                }
        }
        else {
                /* it's already happened; don't do wait_event overhead */
                pd->port_rcvnowait++;
        }

        clear_bit(bit, &dd->ipath_rcvctrl);
        ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);

        return 0;
}

static int try_alloc_port(struct ipath_devdata *dd, int port,
                          struct file *fp)
{
        int ret;

        if (!dd->ipath_pd[port]) {
                void *p, *ptmp;

                p = kzalloc(sizeof(struct ipath_portdata), GFP_KERNEL);

                /*
                 * Allocate memory for use in ipath_tid_update() just once
                 * at open, not per call.  Reduces cost of expected send
                 * setup.
                 */
                ptmp = kmalloc(dd->ipath_rcvtidcnt * sizeof(u16) +
                               dd->ipath_rcvtidcnt * sizeof(struct page **),
                               GFP_KERNEL);
                if (!p || !ptmp) {
                        ipath_dev_err(dd, "Unable to allocate portdata "
                                      "memory, failing open\n");
                        ret = -ENOMEM;
                        kfree(p);
                        kfree(ptmp);
                        goto bail;
                }
                dd->ipath_pd[port] = p;
                dd->ipath_pd[port]->port_port = port;
                dd->ipath_pd[port]->port_dd = dd;
                dd->ipath_pd[port]->port_tid_pg_list = ptmp;
                init_waitqueue_head(&dd->ipath_pd[port]->port_wait);
        }
        if (!dd->ipath_pd[port]->port_cnt) {
                dd->ipath_pd[port]->port_cnt = 1;
                fp->private_data = (void *) dd->ipath_pd[port];
                ipath_cdbg(PROC, "%s[%u] opened unit:port %u:%u\n",
                           current->comm, current->pid, dd->ipath_unit,
                           port);
                dd->ipath_pd[port]->port_pid = current->pid;
                strncpy(dd->ipath_pd[port]->port_comm, current->comm,
                        sizeof(dd->ipath_pd[port]->port_comm));
                ipath_stats.sps_ports++;
                ret = 0;
                goto bail;
        }
        ret = -EBUSY;

bail:
        return ret;
}

static inline int usable(struct ipath_devdata *dd)
{
        return dd &&
                (dd->ipath_flags & IPATH_PRESENT) &&
                dd->ipath_kregbase &&
                dd->ipath_lid &&
                !(dd->ipath_flags & (IPATH_LINKDOWN | IPATH_DISABLED
                                     | IPATH_LINKUNK));
}

static int find_free_port(int unit, struct file *fp)
{
        struct ipath_devdata *dd = ipath_lookup(unit);
        int ret, i;

        if (!dd) {
                ret = -ENODEV;
                goto bail;
        }

        if (!usable(dd)) {
                ret = -ENETDOWN;
                goto bail;
        }

        for (i = 0; i < dd->ipath_cfgports; i++) {
                ret = try_alloc_port(dd, i, fp);
                if (ret != -EBUSY)
                        goto bail;
        }
        ret = -EBUSY;

bail:
        return ret;
}

static int find_best_unit(struct file *fp)
{
        int ret = 0, i, prefunit = -1, devmax;
        int maxofallports, npresent, nup;
        int ndev;

        (void) ipath_count_units(&npresent, &nup, &maxofallports);

        /*
         * This code is present to allow a knowledgeable person to
         * specify the layout of processes to processors before opening
         * this driver, and then we'll assign the process to the "closest"
         * HT-400 to that processor (we assume reasonable connectivity,
         * for now).  This code assumes that if affinity has been set
         * before this point, that at most one cpu is set; for now this
         * is reasonable.  I check for both cpus_empty() and cpus_full(),
         * in case some kernel variant sets none of the bits when no
         * affinity is set.  2.6.11 and 12 kernels have all present
         * cpus set.  Some day we'll have to fix it up further to handle
         * a cpu subset.  This algorithm fails for two HT-400's connected
         * in tunnel fashion.  Eventually this needs real topology
         * information.  There may be some issues with dual core numbering
         * as well.  This needs more work prior to release.
         */
        if (!cpus_empty(current->cpus_allowed) &&
            !cpus_full(current->cpus_allowed)) {
                int ncpus = num_online_cpus(), curcpu = -1;
                for (i = 0; i < ncpus; i++)
                        if (cpu_isset(i, current->cpus_allowed)) {
                                ipath_cdbg(PROC, "%s[%u] affinity set for "
                                           "cpu %d\n", current->comm,
                                           current->pid, i);
                                curcpu = i;
                        }
                if (curcpu != -1) {
                        if (npresent) {
                                prefunit = curcpu / (ncpus / npresent);
                                ipath_dbg("%s[%u] %d chips, %d cpus, "
                                          "%d cpus/chip, select unit %d\n",
                                          current->comm, current->pid,
                                          npresent, ncpus, ncpus / npresent,
                                          prefunit);
                        }
                }
        }

        /*
         * user ports start at 1, kernel port is 0
         * For now, we do round-robin access across all chips
         */

        if (prefunit != -1)
                devmax = prefunit + 1;
        else
                devmax = ipath_count_units(NULL, NULL, NULL);
recheck:
        for (i = 1; i < maxofallports; i++) {
                for (ndev = prefunit != -1 ? prefunit : 0; ndev < devmax;
                     ndev++) {
                        struct ipath_devdata *dd = ipath_lookup(ndev);

                        if (!usable(dd))
                                continue; /* can't use this unit */
                        if (i >= dd->ipath_cfgports)
                                /*
                                 * Maxed out on users of this unit. Try
                                 * next.
                                 */
                                continue;
                        ret = try_alloc_port(dd, i, fp);
                        if (!ret)
                                goto done;
                }
        }

        if (npresent) {
                if (nup == 0) {
                        ret = -ENETDOWN;
                        ipath_dbg("No ports available (none initialized "
                                  "and ready)\n");
                } else {
                        if (prefunit > 0) {
                                /* if started above 0, retry from 0 */
                                ipath_cdbg(PROC,
                                           "%s[%u] no ports on prefunit "
                                           "%d, clear and re-check\n",
                                           current->comm, current->pid,
                                           prefunit);
                                devmax = ipath_count_units(NULL, NULL,
                                                           NULL);
                                prefunit = -1;
                                goto recheck;
                        }
                        ret = -EBUSY;
                        ipath_dbg("No ports available\n");
                }
        } else {
                ret = -ENXIO;
                ipath_dbg("No boards found\n");
        }

done:
        return ret;
}

static int ipath_open(struct inode *in, struct file *fp)
{
        int ret, user_minor;

        mutex_lock(&ipath_mutex);

        user_minor = iminor(in) - IPATH_USER_MINOR_BASE;
        ipath_cdbg(VERBOSE, "open on dev %lx (minor %d)\n",
                   (long)in->i_rdev, user_minor);

        if (user_minor)
                ret = find_free_port(user_minor - 1, fp);
        else
                ret = find_best_unit(fp);

        mutex_unlock(&ipath_mutex);
        return ret;
}

/**
 * unlock_exptid - unlock any expected TID entries port still had in use
 * @pd: port
 *
 * We don't actually update the chip here, because we do a bulk update
 * below, using ipath_f_clear_tids.
 */
static void unlock_expected_tids(struct ipath_portdata *pd)
{
        struct ipath_devdata *dd = pd->port_dd;
        int port_tidbase = pd->port_port * dd->ipath_rcvtidcnt;
        int i, cnt = 0, maxtid = port_tidbase + dd->ipath_rcvtidcnt;

        ipath_cdbg(VERBOSE, "Port %u unlocking any locked expTID pages\n",
                   pd->port_port);
        for (i = port_tidbase; i < maxtid; i++) {
                if (!dd->ipath_pageshadow[i])
                        continue;

                ipath_release_user_pages_on_close(&dd->ipath_pageshadow[i],
                                                  1);
                dd->ipath_pageshadow[i] = NULL;
                cnt++;
                ipath_stats.sps_pageunlocks++;
        }
        if (cnt)
                ipath_cdbg(VERBOSE, "Port %u locked %u expTID entries\n",
                           pd->port_port, cnt);

        if (ipath_stats.sps_pagelocks || ipath_stats.sps_pageunlocks)
                ipath_cdbg(VERBOSE, "%llu pages locked, %llu unlocked\n",
                           (unsigned long long) ipath_stats.sps_pagelocks,
                           (unsigned long long)
                           ipath_stats.sps_pageunlocks);
}

static int ipath_close(struct inode *in, struct file *fp)
{
        int ret = 0;
        struct ipath_portdata *pd;
        struct ipath_devdata *dd;
        unsigned port;

        ipath_cdbg(VERBOSE, "close on dev %lx, private data %p\n",
                   (long)in->i_rdev, fp->private_data);

        mutex_lock(&ipath_mutex);

        pd = port_fp(fp);
        port = pd->port_port;
        fp->private_data = NULL;
        dd = pd->port_dd;

        if (pd->port_hdrqfull) {
                ipath_cdbg(PROC, "%s[%u] had %u rcvhdrqfull errors "
                           "during run\n", pd->port_comm, pd->port_pid,
                           pd->port_hdrqfull);
                pd->port_hdrqfull = 0;
        }

        if (pd->port_rcvwait_to || pd->port_piowait_to
            || pd->port_rcvnowait || pd->port_pionowait) {
                ipath_cdbg(VERBOSE, "port%u, %u rcv, %u pio wait timeo; "
                           "%u rcv %u, pio already\n",
                           pd->port_port, pd->port_rcvwait_to,
                           pd->port_piowait_to, pd->port_rcvnowait,
                           pd->port_pionowait);
                pd->port_rcvwait_to = pd->port_piowait_to =
                        pd->port_rcvnowait = pd->port_pionowait = 0;
        }
        if (pd->port_flag) {
                ipath_dbg("port %u port_flag still set to 0x%lx\n",
                          pd->port_port, pd->port_flag);
                pd->port_flag = 0;
        }

        if (dd->ipath_kregbase) {
                int i;
                /* atomically clear receive enable port. */
                clear_bit(INFINIPATH_R_PORTENABLE_SHIFT + port,
                          &dd->ipath_rcvctrl);
                ipath_write_kreg( dd, dd->ipath_kregs->kr_rcvctrl,
                        dd->ipath_rcvctrl);
                /* and read back from chip to be sure that nothing
                 * else is in flight when we do the rest */
                (void)ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);

                /* clean up the pkeys for this port user */
                ipath_clean_part_key(pd, dd);


                /*
                 * be paranoid, and never write 0's to these, just use an
                 * unused part of the port 0 tail page.  Of course,
                 * rcvhdraddr points to a large chunk of memory, so this
                 * could still trash things, but at least it won't trash
                 * page 0, and by disabling the port, it should stop "soon",
                 * even if a packet or two is in already in flight after we
                 * disabled the port.
                 */
                ipath_write_kreg_port(dd,
                        dd->ipath_kregs->kr_rcvhdrtailaddr, port,
                        dd->ipath_dummy_hdrq_phys);
                ipath_write_kreg_port(dd, dd->ipath_kregs->kr_rcvhdraddr,
                        pd->port_port, dd->ipath_dummy_hdrq_phys);

                i = dd->ipath_pbufsport * (port - 1);
                ipath_disarm_piobufs(dd, i, dd->ipath_pbufsport);

                if (dd->ipath_pageshadow)
                        unlock_expected_tids(pd);
                ipath_stats.sps_ports--;
                ipath_cdbg(PROC, "%s[%u] closed port %u:%u\n",
                           pd->port_comm, pd->port_pid,
                           dd->ipath_unit, port);

                dd->ipath_f_clear_tids(dd, pd->port_port);
        }

        pd->port_cnt = 0;
        pd->port_pid = 0;

        dd->ipath_pd[pd->port_port] = NULL; /* before releasing mutex */
        mutex_unlock(&ipath_mutex);
        ipath_free_pddata(dd, pd); /* after releasing the mutex */

        return ret;
}

static int ipath_port_info(struct ipath_portdata *pd,
                           struct ipath_port_info __user *uinfo)
{
        struct ipath_port_info info;
        int nup;
        int ret;

        (void) ipath_count_units(NULL, &nup, NULL);
        info.num_active = nup;
        info.unit = pd->port_dd->ipath_unit;
        info.port = pd->port_port;

        if (copy_to_user(uinfo, &info, sizeof(info))) {
                ret = -EFAULT;
                goto bail;
        }
        ret = 0;

bail:
        return ret;
}

static ssize_t ipath_write(struct file *fp, const char __user *data,
                           size_t count, loff_t *off)
{
        const struct ipath_cmd __user *ucmd;
        struct ipath_portdata *pd;
        const void __user *src;
        size_t consumed, copy;
        struct ipath_cmd cmd;
        ssize_t ret = 0;
        void *dest;

        if (count < sizeof(cmd.type)) {
                ret = -EINVAL;
                goto bail;
        }

        ucmd = (const struct ipath_cmd __user *) data;

        if (copy_from_user(&cmd.type, &ucmd->type, sizeof(cmd.type))) {
                ret = -EFAULT;
                goto bail;
        }

        consumed = sizeof(cmd.type);

        switch (cmd.type) {
        case IPATH_CMD_USER_INIT:
                copy = sizeof(cmd.cmd.user_info);
                dest = &cmd.cmd.user_info;
                src = &ucmd->cmd.user_info;
                break;
        case IPATH_CMD_RECV_CTRL:
                copy = sizeof(cmd.cmd.recv_ctrl);
                dest = &cmd.cmd.recv_ctrl;
                src = &ucmd->cmd.recv_ctrl;
                break;
        case IPATH_CMD_PORT_INFO:
                copy = sizeof(cmd.cmd.port_info);
                dest = &cmd.cmd.port_info;
                src = &ucmd->cmd.port_info;
                break;
        case IPATH_CMD_TID_UPDATE:
        case IPATH_CMD_TID_FREE:
                copy = sizeof(cmd.cmd.tid_info);
                dest = &cmd.cmd.tid_info;
                src = &ucmd->cmd.tid_info;
                break;
        case IPATH_CMD_SET_PART_KEY:
                copy = sizeof(cmd.cmd.part_key);
                dest = &cmd.cmd.part_key;
                src = &ucmd->cmd.part_key;
                break;
        default:
                ret = -EINVAL;
                goto bail;
        }

        if ((count - consumed) < copy) {
                ret = -EINVAL;
                goto bail;
        }

        if (copy_from_user(dest, src, copy)) {
                ret = -EFAULT;
                goto bail;
        }

        consumed += copy;
        pd = port_fp(fp);

        switch (cmd.type) {
        case IPATH_CMD_USER_INIT:
                ret = ipath_do_user_init(pd, &cmd.cmd.user_info);
                if (ret < 0)
                        goto bail;
                ret = ipath_get_base_info(
                        pd, (void __user *) (unsigned long)
                        cmd.cmd.user_info.spu_base_info,
                        cmd.cmd.user_info.spu_base_info_size);
                break;
        case IPATH_CMD_RECV_CTRL:
                ret = ipath_manage_rcvq(pd, cmd.cmd.recv_ctrl);
                break;
        case IPATH_CMD_PORT_INFO:
                ret = ipath_port_info(pd,
                                      (struct ipath_port_info __user *)
                                      (unsigned long) cmd.cmd.port_info);
                break;
        case IPATH_CMD_TID_UPDATE:
                ret = ipath_tid_update(pd, &cmd.cmd.tid_info);
                break;
        case IPATH_CMD_TID_FREE:
                ret = ipath_tid_free(pd, &cmd.cmd.tid_info);
                break;
        case IPATH_CMD_SET_PART_KEY:
                ret = ipath_set_part_key(pd, cmd.cmd.part_key);
                break;
        }

        if (ret >= 0)
                ret = consumed;

bail:
        return ret;
}

static struct class *ipath_class;

static int init_cdev(int minor, char *name, struct file_operations *fops,
                     struct cdev **cdevp, struct class_device **class_devp)
{
        const dev_t dev = MKDEV(IPATH_MAJOR, minor);
        struct cdev *cdev = NULL;
        struct class_device *class_dev = NULL;
        int ret;

        cdev = cdev_alloc();
        if (!cdev) {
                printk(KERN_ERR IPATH_DRV_NAME
                       ": Could not allocate cdev for minor %d, %s\n",
                       minor, name);
                ret = -ENOMEM;
                goto done;
        }

        cdev->owner = THIS_MODULE;
        cdev->ops = fops;
        kobject_set_name(&cdev->kobj, name);

        ret = cdev_add(cdev, dev, 1);
        if (ret < 0) {
                printk(KERN_ERR IPATH_DRV_NAME
                       ": Could not add cdev for minor %d, %s (err %d)\n",
                       minor, name, -ret);
                goto err_cdev;
        }

        class_dev = class_device_create(ipath_class, NULL, dev, NULL, name);

        if (IS_ERR(class_dev)) {
                ret = PTR_ERR(class_dev);
                printk(KERN_ERR IPATH_DRV_NAME ": Could not create "
                       "class_dev for minor %d, %s (err %d)\n",
                       minor, name, -ret);
                goto err_cdev;
        }

        goto done;

err_cdev:
        cdev_del(cdev);
        cdev = NULL;

done:
        if (ret >= 0) {
                *cdevp = cdev;
                *class_devp = class_dev;
        } else {
                *cdevp = NULL;
                *class_devp = NULL;
        }

        return ret;
}

int ipath_cdev_init(int minor, char *name, struct file_operations *fops,
                    struct cdev **cdevp, struct class_device **class_devp)
{
        return init_cdev(minor, name, fops, cdevp, class_devp);
}

static void cleanup_cdev(struct cdev **cdevp,
                         struct class_device **class_devp)
{
        struct class_device *class_dev = *class_devp;

        if (class_dev) {
                class_device_unregister(class_dev);
                *class_devp = NULL;
        }

        if (*cdevp) {
                cdev_del(*cdevp);
                *cdevp = NULL;
        }
}

void ipath_cdev_cleanup(struct cdev **cdevp,
                        struct class_device **class_devp)
{
        cleanup_cdev(cdevp, class_devp);
}

static struct cdev *wildcard_cdev;
static struct class_device *wildcard_class_dev;

static const dev_t dev = MKDEV(IPATH_MAJOR, 0);

static int user_init(void)
{
        int ret;

        ret = register_chrdev_region(dev, IPATH_NMINORS, IPATH_DRV_NAME);
        if (ret < 0) {
                printk(KERN_ERR IPATH_DRV_NAME ": Could not register "
                       "chrdev region (err %d)\n", -ret);
                goto done;
        }

        ipath_class = class_create(THIS_MODULE, IPATH_DRV_NAME);

        if (IS_ERR(ipath_class)) {
                ret = PTR_ERR(ipath_class);
                printk(KERN_ERR IPATH_DRV_NAME ": Could not create "
                       "device class (err %d)\n", -ret);
                goto bail;
        }

        goto done;
bail:
        unregister_chrdev_region(dev, IPATH_NMINORS);
done:
        return ret;
}

static void user_cleanup(void)
{
        if (ipath_class) {
                class_destroy(ipath_class);
                ipath_class = NULL;
        }

        unregister_chrdev_region(dev, IPATH_NMINORS);
}

static atomic_t user_count = ATOMIC_INIT(0);
static atomic_t user_setup = ATOMIC_INIT(0);

int ipath_user_add(struct ipath_devdata *dd)
{
        char name[10];
        int ret;

        if (atomic_inc_return(&user_count) == 1) {
                ret = user_init();
                if (ret < 0) {
                        ipath_dev_err(dd, "Unable to set up user support: "
                                      "error %d\n", -ret);
                        goto bail;
                }
                ret = init_cdev(0, "ipath", &ipath_file_ops, &wildcard_cdev,
                                &wildcard_class_dev);
                if (ret < 0) {
                        ipath_dev_err(dd, "Could not create wildcard "
                                      "minor: error %d\n", -ret);
                        goto bail_sma;
                }

                atomic_set(&user_setup, 1);
        }

        snprintf(name, sizeof(name), "ipath%d", dd->ipath_unit);

        ret = init_cdev(dd->ipath_unit + 1, name, &ipath_file_ops,
                        &dd->user_cdev, &dd->user_class_dev);
        if (ret < 0)
                ipath_dev_err(dd, "Could not create user minor %d, %s\n",
                              dd->ipath_unit + 1, name);

        goto bail;

bail_sma:
        user_cleanup();
bail:
        return ret;
}

void ipath_user_remove(struct ipath_devdata *dd)
{
        cleanup_cdev(&dd->user_cdev, &dd->user_class_dev);

        if (atomic_dec_return(&user_count) == 0) {
                if (atomic_read(&user_setup) == 0)
                        goto bail;

                cleanup_cdev(&wildcard_cdev, &wildcard_class_dev);
                user_cleanup();

                atomic_set(&user_setup, 0);
        }
bail:
        return;
}