drivers/staging/rdma/hfi1/iowait.h

   1 #ifndef _HFI1_IOWAIT_H
   2 #define _HFI1_IOWAIT_H
   3 /*
   4  *
   5  * This file is provided under a dual BSD/GPLv2 license.  When using or
   6  * redistributing this file, you may do so under either license.
   7  *
   8  * GPL LICENSE SUMMARY
   9  *
  10  * Copyright(c) 2015 Intel Corporation.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of version 2 of the GNU General Public License as
  14  * published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * General Public License for more details.
  20  *
  21  * BSD LICENSE
  22  *
  23  * Copyright(c) 2015 Intel Corporation.
  24  *
  25  * Redistribution and use in source and binary forms, with or without
  26  * modification, are permitted provided that the following conditions
  27  * are met:
  28  *
  29  *  - Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  *  - Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in
  33  *    the documentation and/or other materials provided with the
  34  *    distribution.
  35  *  - Neither the name of Intel Corporation nor the names of its
  36  *    contributors may be used to endorse or promote products derived
  37  *    from this software without specific prior written permission.
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  40  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  41  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  42  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  43  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  45  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  46  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  47  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  48  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  49  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  50  *
  51  */
  52
  53 #include <linux/list.h>
  54 #include <linux/workqueue.h>
  55 #include <linux/sched.h>
  56
  57 /*
  58  * typedef (*restart_t)() - restart callback
  59  * @work: pointer to work structure
  60  */
  61 typedef void (*restart_t)(struct work_struct *work);
  62
  63 struct sdma_txreq;
  64 struct sdma_engine;
  65 /**
  66  * struct iowait - linkage for delayed progress/waiting
  67  * @list: used to add/insert into QP/PQ wait lists
  68  * @tx_head: overflow list of sdma_txreq's
  69  * @sleep: no space callback
  70  * @wakeup: space callback
  71  * @iowork: workqueue overhead
  72  * @wait_dma: wait for sdma_busy == 0
  73  * @sdma_busy: # of packets in flight
  74  * @count: total number of descriptors in tx_head'ed list
  75  * @tx_limit: limit for overflow queuing
  76  * @tx_count: number of tx entry's in tx_head'ed list
  77  *
  78  * This is to be embedded in user's state structure
  79  * (QP or PQ).
  80  *
  81  * The sleep and wakeup members are a
  82  * bit misnamed.   They do not strictly
  83  * speaking sleep or wake up, but they
  84  * are callbacks for the ULP to implement
  85  * what ever queuing/dequeuing of
  86  * the embedded iowait and its containing struct
  87  * when a resource shortage like SDMA ring space is seen.
  88  *
  89  * Both potentially have locks help
  90  * so sleeping is not allowed.
  91  *
  92  * The wait_dma member along with the iow
  93  */
  94
  95 struct iowait {
  96         struct list_head list;
  97         struct list_head tx_head;
  98         int (*sleep)(
  99                 struct sdma_engine *sde,
 100                 struct iowait *wait,
 101                 struct sdma_txreq *tx,
 102                 unsigned seq);
 103         void (*wakeup)(struct iowait *wait, int reason);
 104         struct work_struct iowork;
 105         wait_queue_head_t wait_dma;
 106         atomic_t sdma_busy;
 107         u32 count;
 108         u32 tx_limit;
 109         u32 tx_count;
 110 };
 111
 112 #define SDMA_AVAIL_REASON 0
 113
 114 /**
 115  * iowait_init() - initialize wait structure
 116  * @wait: wait struct to initialize
 117  * @tx_limit: limit for overflow queuing
 118  * @func: restart function for workqueue
 119  * @sleep: sleep function for no space
 120  * @wakeup: wakeup function for no space
 121  *
 122  * This function initializes the iowait
 123  * structure embedded in the QP or PQ.
 124  *
 125  */
 126
 127 static inline void iowait_init(
 128         struct iowait *wait,
 129         u32 tx_limit,
 130         void (*func)(struct work_struct *work),
 131         int (*sleep)(
 132                 struct sdma_engine *sde,
 133                 struct iowait *wait,
 134                 struct sdma_txreq *tx,
 135                 unsigned seq),
 136         void (*wakeup)(struct iowait *wait, int reason))
 137 {
 138         wait->count = 0;
 139         INIT_LIST_HEAD(&wait->list);
 140         INIT_LIST_HEAD(&wait->tx_head);
 141         INIT_WORK(&wait->iowork, func);
 142         init_waitqueue_head(&wait->wait_dma);
 143         atomic_set(&wait->sdma_busy, 0);
 144         wait->tx_limit = tx_limit;
 145         wait->sleep = sleep;
 146         wait->wakeup = wakeup;
 147 }
 148
 149 /**
 150  * iowait_schedule() - initialize wait structure
 151  * @wait: wait struct to schedule
 152  * @wq: workqueue for schedule
 153  * @cpu: cpu
 154  */
 155 static inline void iowait_schedule(
 156         struct iowait *wait,
 157         struct workqueue_struct *wq,
 158         int cpu)
 159 {
 160         queue_work_on(cpu, wq, &wait->iowork);
 161 }
 162
 163 /**
 164  * iowait_sdma_drain() - wait for DMAs to drain
 165  *
 166  * @wait: iowait structure
 167  *
 168  * This will delay until the iowait sdmas have
 169  * completed.
 170  */
 171 static inline void iowait_sdma_drain(struct iowait *wait)
 172 {
 173         wait_event(wait->wait_dma, !atomic_read(&wait->sdma_busy));
 174 }
 175
 176 /**
 177  * iowait_drain_wakeup() - trigger iowait_drain() waiter
 178  *
 179  * @wait: iowait structure
 180  *
 181  * This will trigger any waiters.
 182  */
 183 static inline void iowait_drain_wakeup(struct iowait *wait)
 184 {
 185         wake_up(&wait->wait_dma);
 186 }
 187
 188 #endif