/*
 * Copyright (c) 2008, 2009, 2010 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/spinlock.h>
#include <linux/pci.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/moduleparam.h>

#include "qib.h"

static unsigned qib_hol_timeout_ms = 3000;
module_param_named(hol_timeout_ms, qib_hol_timeout_ms, uint, S_IRUGO);
MODULE_PARM_DESC(hol_timeout_ms,
                 "duration of user app suspension after link failure");

unsigned qib_sdma_fetch_arb = 1;
module_param_named(fetch_arb, qib_sdma_fetch_arb, uint, S_IRUGO);
MODULE_PARM_DESC(fetch_arb, "IBA7220: change SDMA descriptor arbitration");

/**
 * qib_disarm_piobufs - cancel a range of PIO buffers
 * @dd: the qlogic_ib device
 * @first: the first PIO buffer to cancel
 * @cnt: the number of PIO buffers to cancel
 *
 * Cancel a range of PIO buffers. Used at user process close,
 * in case it died while writing to a PIO buffer.
 */
void qib_disarm_piobufs(struct qib_devdata *dd, unsigned first, unsigned cnt)
{
        unsigned long flags;
        unsigned i;
        unsigned last;

        last = first + cnt;
        spin_lock_irqsave(&dd->pioavail_lock, flags);
        for (i = first; i < last; i++) {
                __clear_bit(i, dd->pio_need_disarm);
                dd->f_sendctrl(dd->pport, QIB_SENDCTRL_DISARM_BUF(i));
        }
        spin_unlock_irqrestore(&dd->pioavail_lock, flags);
}

/*
 * This is called by a user process when it sees the DISARM_BUFS event
 * bit is set.
 */
int qib_disarm_piobufs_ifneeded(struct qib_ctxtdata *rcd)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned i;
        unsigned last;
        unsigned n = 0;

        last = rcd->pio_base + rcd->piocnt;
        /*
         * Don't need uctxt_lock here, since user has called in to us.
         * Clear at start in case more interrupts set bits while we
         * are disarming
         */
        if (rcd->user_event_mask) {
                /*
                 * subctxt_cnt is 0 if not shared, so do base
                 * separately, first, then remaining subctxt, if any
                 */
                clear_bit(_QIB_EVENT_DISARM_BUFS_BIT, &rcd->user_event_mask[0]);
                for (i = 1; i < rcd->subctxt_cnt; i++)
                        clear_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                  &rcd->user_event_mask[i]);
        }
        spin_lock_irq(&dd->pioavail_lock);
        for (i = rcd->pio_base; i < last; i++) {
                if (__test_and_clear_bit(i, dd->pio_need_disarm)) {
                        n++;
                        dd->f_sendctrl(rcd->ppd, QIB_SENDCTRL_DISARM_BUF(i));
                }
        }
        spin_unlock_irq(&dd->pioavail_lock);
        return 0;
}

static struct qib_pportdata *is_sdma_buf(struct qib_devdata *dd, unsigned i)
{
        struct qib_pportdata *ppd;
        unsigned pidx;

        for (pidx = 0; pidx < dd->num_pports; pidx++) {
                ppd = dd->pport + pidx;
                if (i >= ppd->sdma_state.first_sendbuf &&
                    i < ppd->sdma_state.last_sendbuf)
                        return ppd;
        }
        return NULL;
}

/*
 * Return true if send buffer is being used by a user context.
 * Sets  _QIB_EVENT_DISARM_BUFS_BIT in user_event_mask as a side effect
 */
static int find_ctxt(struct qib_devdata *dd, unsigned bufn)
{
        struct qib_ctxtdata *rcd;
        unsigned ctxt;
        int ret = 0;

        spin_lock(&dd->uctxt_lock);
        for (ctxt = dd->first_user_ctxt; ctxt < dd->cfgctxts; ctxt++) {
                rcd = dd->rcd[ctxt];
                if (!rcd || bufn < rcd->pio_base ||
                    bufn >= rcd->pio_base + rcd->piocnt)
                        continue;
                if (rcd->user_event_mask) {
                        int i;
                        /*
                         * subctxt_cnt is 0 if not shared, so do base
                         * separately, first, then remaining subctxt, if any
                         */
                        set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                &rcd->user_event_mask[0]);
                        for (i = 1; i < rcd->subctxt_cnt; i++)
                                set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                        &rcd->user_event_mask[i]);
                }
                ret = 1;
                break;
        }
        spin_unlock(&dd->uctxt_lock);

        return ret;
}

/*
 * Disarm a set of send buffers.  If the buffer might be actively being
 * written to, mark the buffer to be disarmed later when it is not being
 * written to.
 *
 * This should only be called from the IRQ error handler.
 */
void qib_disarm_piobufs_set(struct qib_devdata *dd, unsigned long *mask,
                            unsigned cnt)
{
        struct qib_pportdata *ppd, *pppd[QIB_MAX_IB_PORTS];
        unsigned i;
        unsigned long flags;

        for (i = 0; i < dd->num_pports; i++)
                pppd[i] = NULL;

        for (i = 0; i < cnt; i++) {
                if (!test_bit(i, mask))
                        continue;
                /*
                 * If the buffer is owned by the DMA hardware,
                 * reset the DMA engine.
                 */
                ppd = is_sdma_buf(dd, i);
                if (ppd) {
                        pppd[ppd->port] = ppd;
                        continue;
                }
                /*
                 * If the kernel is writing the buffer or the buffer is
                 * owned by a user process, we can't clear it yet.
                 */
                spin_lock_irqsave(&dd->pioavail_lock, flags);
                if (test_bit(i, dd->pio_writing) ||
                    (!test_bit(i << 1, dd->pioavailkernel) &&
                     find_ctxt(dd, i))) {
                        __set_bit(i, dd->pio_need_disarm);
                } else {
                        dd->f_sendctrl(dd->pport, QIB_SENDCTRL_DISARM_BUF(i));
                }
                spin_unlock_irqrestore(&dd->pioavail_lock, flags);
        }

        /* do cancel_sends once per port that had sdma piobufs in error */
        for (i = 0; i < dd->num_pports; i++)
                if (pppd[i])
                        qib_cancel_sends(pppd[i]);
}

/**
 * update_send_bufs - update shadow copy of the PIO availability map
 * @dd: the qlogic_ib device
 *
 * called whenever our local copy indicates we have run out of send buffers
 */
static void update_send_bufs(struct qib_devdata *dd)
{
        unsigned long flags;
        unsigned i;
        const unsigned piobregs = dd->pioavregs;

        /*
         * If the generation (check) bits have changed, then we update the
         * busy bit for the corresponding PIO buffer.  This algorithm will
         * modify positions to the value they already have in some cases
         * (i.e., no change), but it's faster than changing only the bits
         * that have changed.
         *
         * We would like to do this atomicly, to avoid spinlocks in the
         * critical send path, but that's not really possible, given the
         * type of changes, and that this routine could be called on
         * multiple cpu's simultaneously, so we lock in this routine only,
         * to avoid conflicting updates; all we change is the shadow, and
         * it's a single 64 bit memory location, so by definition the update
         * is atomic in terms of what other cpu's can see in testing the
         * bits.  The spin_lock overhead isn't too bad, since it only
         * happens when all buffers are in use, so only cpu overhead, not
         * latency or bandwidth is affected.
         */
        if (!dd->pioavailregs_dma)
                return;
        spin_lock_irqsave(&dd->pioavail_lock, flags);
        for (i = 0; i < piobregs; i++) {
                u64 pchbusy, pchg, piov, pnew;

                piov = le64_to_cpu(dd->pioavailregs_dma[i]);
                pchg = dd->pioavailkernel[i] &
                        ~(dd->pioavailshadow[i] ^ piov);
                pchbusy = pchg << QLOGIC_IB_SENDPIOAVAIL_BUSY_SHIFT;
                if (pchg && (pchbusy & dd->pioavailshadow[i])) {
                        pnew = dd->pioavailshadow[i] & ~pchbusy;
                        pnew |= piov & pchbusy;
                        dd->pioavailshadow[i] = pnew;
                }
        }
        spin_unlock_irqrestore(&dd->pioavail_lock, flags);
}

/*
 * Debugging code and stats updates if no pio buffers available.
 */
static noinline void no_send_bufs(struct qib_devdata *dd)
{
        dd->upd_pio_shadow = 1;

        /* not atomic, but if we lose a stat count in a while, that's OK */
        qib_stats.sps_nopiobufs++;
}

/*
 * Common code for normal driver send buffer allocation, and reserved
 * allocation.
 *
 * Do appropriate marking as busy, etc.
 * Returns buffer pointer if one is found, otherwise NULL.
 */
u32 __iomem *qib_getsendbuf_range(struct qib_devdata *dd, u32 *pbufnum,
                                  u32 first, u32 last)
{
        unsigned i, j, updated = 0;
        unsigned nbufs;
        unsigned long flags;
        unsigned long *shadow = dd->pioavailshadow;
        u32 __iomem *buf;

        if (!(dd->flags & QIB_PRESENT))
                return NULL;

        nbufs = last - first + 1; /* number in range to check */
        if (dd->upd_pio_shadow) {
update_shadow:
                /*
                 * Minor optimization.  If we had no buffers on last call,
                 * start out by doing the update; continue and do scan even
                 * if no buffers were updated, to be paranoid.
                 */
                update_send_bufs(dd);
                updated++;
        }
        i = first;
        /*
         * While test_and_set_bit() is atomic, we do that and then the
         * change_bit(), and the pair is not.  See if this is the cause
         * of the remaining armlaunch errors.
         */
        spin_lock_irqsave(&dd->pioavail_lock, flags);
        if (dd->last_pio >= first && dd->last_pio <= last)
                i = dd->last_pio + 1;
        if (!first)
                /* adjust to min possible  */
                nbufs = last - dd->min_kernel_pio + 1;
        for (j = 0; j < nbufs; j++, i++) {
                if (i > last)
                        i = !first ? dd->min_kernel_pio : first;
                if (__test_and_set_bit((2 * i) + 1, shadow))
                        continue;
                /* flip generation bit */
                __change_bit(2 * i, shadow);
                /* remember that the buffer can be written to now */
                __set_bit(i, dd->pio_writing);
                if (!first && first != last) /* first == last on VL15, avoid */
                        dd->last_pio = i;
                break;
        }
        spin_unlock_irqrestore(&dd->pioavail_lock, flags);

        if (j == nbufs) {
                if (!updated)
                        /*
                         * First time through; shadow exhausted, but may be
                         * buffers available, try an update and then rescan.
                         */
                        goto update_shadow;
                no_send_bufs(dd);
                buf = NULL;
        } else {
                if (i < dd->piobcnt2k)
                        buf = (u32 __iomem *)(dd->pio2kbase +
                                i * dd->palign);
                else if (i < dd->piobcnt2k + dd->piobcnt4k || !dd->piovl15base)
                        buf = (u32 __iomem *)(dd->pio4kbase +
                                (i - dd->piobcnt2k) * dd->align4k);
                else
                        buf = (u32 __iomem *)(dd->piovl15base +
                                (i - (dd->piobcnt2k + dd->piobcnt4k)) *
                                dd->align4k);
                if (pbufnum)
                        *pbufnum = i;
                dd->upd_pio_shadow = 0;
        }

        return buf;
}

/*
 * Record that the caller is finished writing to the buffer so we don't
 * disarm it while it is being written and disarm it now if needed.
 */
void qib_sendbuf_done(struct qib_devdata *dd, unsigned n)
{
        unsigned long flags;

        spin_lock_irqsave(&dd->pioavail_lock, flags);
        __clear_bit(n, dd->pio_writing);
        if (__test_and_clear_bit(n, dd->pio_need_disarm))
                dd->f_sendctrl(dd->pport, QIB_SENDCTRL_DISARM_BUF(n));
        spin_unlock_irqrestore(&dd->pioavail_lock, flags);
}

/**
 * qib_chg_pioavailkernel - change which send buffers are available for kernel
 * @dd: the qlogic_ib device
 * @start: the starting send buffer number
 * @len: the number of send buffers
 * @avail: true if the buffers are available for kernel use, false otherwise
 * @rcd: the context pointer
 */
void qib_chg_pioavailkernel(struct qib_devdata *dd, unsigned start,
        unsigned len, u32 avail, struct qib_ctxtdata *rcd)
{
        unsigned long flags;
        unsigned end;
        unsigned ostart = start;

        /* There are two bits per send buffer (busy and generation) */
        start *= 2;
        end = start + len * 2;

        spin_lock_irqsave(&dd->pioavail_lock, flags);
        /* Set or clear the busy bit in the shadow. */
        while (start < end) {
                if (avail) {
                        unsigned long dma;
                        int i;

                        /*
                         * The BUSY bit will never be set, because we disarm
                         * the user buffers before we hand them back to the
                         * kernel.  We do have to make sure the generation
                         * bit is set correctly in shadow, since it could
                         * have changed many times while allocated to user.
                         * We can't use the bitmap functions on the full
                         * dma array because it is always little-endian, so
                         * we have to flip to host-order first.
                         * BITS_PER_LONG is slightly wrong, since it's
                         * always 64 bits per register in chip...
                         * We only work on 64 bit kernels, so that's OK.
                         */
                        i = start / BITS_PER_LONG;
                        __clear_bit(QLOGIC_IB_SENDPIOAVAIL_BUSY_SHIFT + start,
                                    dd->pioavailshadow);
                        dma = (unsigned long)
                                le64_to_cpu(dd->pioavailregs_dma[i]);
                        if (test_bit((QLOGIC_IB_SENDPIOAVAIL_CHECK_SHIFT +
                                      start) % BITS_PER_LONG, &dma))
                                __set_bit(QLOGIC_IB_SENDPIOAVAIL_CHECK_SHIFT +
                                          start, dd->pioavailshadow);
                        else
                                __clear_bit(QLOGIC_IB_SENDPIOAVAIL_CHECK_SHIFT
                                            + start, dd->pioavailshadow);
                        __set_bit(start, dd->pioavailkernel);
                        if ((start >> 1) < dd->min_kernel_pio)
                                dd->min_kernel_pio = start >> 1;
                } else {
                        __set_bit(start + QLOGIC_IB_SENDPIOAVAIL_BUSY_SHIFT,
                                  dd->pioavailshadow);
                        __clear_bit(start, dd->pioavailkernel);
                        if ((start >> 1) > dd->min_kernel_pio)
                                dd->min_kernel_pio = start >> 1;
                }
                start += 2;
        }

        if (dd->min_kernel_pio > 0 && dd->last_pio < dd->min_kernel_pio - 1)
                dd->last_pio = dd->min_kernel_pio - 1;
        spin_unlock_irqrestore(&dd->pioavail_lock, flags);

        dd->f_txchk_change(dd, ostart, len, avail, rcd);
}

/*
 * Flush all sends that might be in the ready to send state, as well as any
 * that are in the process of being sent.  Used whenever we need to be
 * sure the send side is idle.  Cleans up all buffer state by canceling
 * all pio buffers, and issuing an abort, which cleans up anything in the
 * launch fifo.  The cancel is superfluous on some chip versions, but
 * it's safer to always do it.
 * PIOAvail bits are updated by the chip as if a normal send had happened.
 */
void qib_cancel_sends(struct qib_pportdata *ppd)
{
        struct qib_devdata *dd = ppd->dd;
        struct qib_ctxtdata *rcd;
        unsigned long flags;
        unsigned ctxt;
        unsigned i;
        unsigned last;

        /*
         * Tell PSM to disarm buffers again before trying to reuse them.
         * We need to be sure the rcd doesn't change out from under us
         * while we do so.  We hold the two locks sequentially.  We might
         * needlessly set some need_disarm bits as a result, if the
         * context is closed after we release the uctxt_lock, but that's
         * fairly benign, and safer than nesting the locks.
         */
        for (ctxt = dd->first_user_ctxt; ctxt < dd->cfgctxts; ctxt++) {
                spin_lock_irqsave(&dd->uctxt_lock, flags);
                rcd = dd->rcd[ctxt];
                if (rcd && rcd->ppd == ppd) {
                        last = rcd->pio_base + rcd->piocnt;
                        if (rcd->user_event_mask) {
                                /*
                                 * subctxt_cnt is 0 if not shared, so do base
                                 * separately, first, then remaining subctxt,
                                 * if any
                                 */
                                set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                        &rcd->user_event_mask[0]);
                                for (i = 1; i < rcd->subctxt_cnt; i++)
                                        set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                                &rcd->user_event_mask[i]);
                        }
                        i = rcd->pio_base;
                        spin_unlock_irqrestore(&dd->uctxt_lock, flags);
                        spin_lock_irqsave(&dd->pioavail_lock, flags);
                        for (; i < last; i++)
                                __set_bit(i, dd->pio_need_disarm);
                        spin_unlock_irqrestore(&dd->pioavail_lock, flags);
                } else
                        spin_unlock_irqrestore(&dd->uctxt_lock, flags);
        }

        if (!(dd->flags & QIB_HAS_SEND_DMA))
                dd->f_sendctrl(ppd, QIB_SENDCTRL_DISARM_ALL |
                                    QIB_SENDCTRL_FLUSH);
}

/*
 * Force an update of in-memory copy of the pioavail registers, when
 * needed for any of a variety of reasons.
 * If already off, this routine is a nop, on the assumption that the
 * caller (or set of callers) will "do the right thing".
 * This is a per-device operation, so just the first port.
 */
void qib_force_pio_avail_update(struct qib_devdata *dd)
{
        dd->f_sendctrl(dd->pport, QIB_SENDCTRL_AVAIL_BLIP);
}

void qib_hol_down(struct qib_pportdata *ppd)
{
        /*
         * Cancel sends when the link goes DOWN so that we aren't doing it
         * at INIT when we might be trying to send SMI packets.
         */
        if (!(ppd->lflags & QIBL_IB_AUTONEG_INPROG))
                qib_cancel_sends(ppd);
}

/*
 * Link is at INIT.
 * We start the HoL timer so we can detect stuck packets blocking SMP replies.
 * Timer may already be running, so use mod_timer, not add_timer.
 */
void qib_hol_init(struct qib_pportdata *ppd)
{
        if (ppd->hol_state != QIB_HOL_INIT) {
                ppd->hol_state = QIB_HOL_INIT;
                mod_timer(&ppd->hol_timer,
                          jiffies + msecs_to_jiffies(qib_hol_timeout_ms));
        }
}

/*
 * Link is up, continue any user processes, and ensure timer
 * is a nop, if running.  Let timer keep running, if set; it
 * will nop when it sees the link is up.
 */
void qib_hol_up(struct qib_pportdata *ppd)
{
        ppd->hol_state = QIB_HOL_UP;
}

/*
 * This is only called via the timer.
 */
void qib_hol_event(struct timer_list *t)
{
        struct qib_pportdata *ppd = from_timer(ppd, t, hol_timer);

        /* If hardware error, etc, skip. */
        if (!(ppd->dd->flags & QIB_INITTED))
                return;

        if (ppd->hol_state != QIB_HOL_UP) {
                /*
                 * Try to flush sends in case a stuck packet is blocking
                 * SMP replies.
                 */
                qib_hol_down(ppd);
                mod_timer(&ppd->hol_timer,
                          jiffies + msecs_to_jiffies(qib_hol_timeout_ms));
        }
}