crypto/async_tx/async_tx.c

   1 /*
   2  * core routines for the asynchronous memory transfer/transform api
   3  *
   4  * Copyright © 2006, Intel Corporation.
   5  *
   6  *      Dan Williams <dan.j.williams@intel.com>
   7  *
   8  *      with architecture considerations by:
   9  *      Neil Brown <neilb@suse.de>
  10  *      Jeff Garzik <jeff@garzik.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms and conditions of the GNU General Public License,
  14  * version 2, as published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope it will be useful, but WITHOUT
  17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  19  * more details.
  20  *
  21  * You should have received a copy of the GNU General Public License along with
  22  * this program; if not, write to the Free Software Foundation, Inc.,
  23  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  24  *
  25  */
  26 #include <linux/rculist.h>
  27 #include <linux/module.h>
  28 #include <linux/kernel.h>
  29 #include <linux/async_tx.h>
  30
  31 #ifdef CONFIG_DMA_ENGINE
  32 static int __init async_tx_init(void)
  33 {
  34         async_dmaengine_get();
  35
  36         printk(KERN_INFO "async_tx: api initialized (async)\n");
  37
  38         return 0;
  39 }
  40
  41 static void __exit async_tx_exit(void)
  42 {
  43         async_dmaengine_put();
  44 }
  45
  46 module_init(async_tx_init);
  47 module_exit(async_tx_exit);
  48
  49 /**
  50  * __async_tx_find_channel - find a channel to carry out the operation or let
  51  *      the transaction execute synchronously
  52  * @submit: transaction dependency and submission modifiers
  53  * @tx_type: transaction type
  54  */
  55 struct dma_chan *
  56 __async_tx_find_channel(struct async_submit_ctl *submit,
  57                         enum dma_transaction_type tx_type)
  58 {
  59         struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
  60
  61         /* see if we can keep the chain on one channel */
  62         if (depend_tx &&
  63             dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
  64                 return depend_tx->chan;
  65         return async_dma_find_channel(tx_type);
  66 }
  67 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
  68 #endif
  69
  70
  71 /**
  72  * async_tx_channel_switch - queue an interrupt descriptor with a dependency
  73  *      pre-attached.
  74  * @depend_tx: the operation that must finish before the new operation runs
  75  * @tx: the new operation
  76  */
  77 static void
  78 async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
  79                         struct dma_async_tx_descriptor *tx)
  80 {
  81         struct dma_chan *chan = depend_tx->chan;
  82         struct dma_device *device = chan->device;
  83         struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
  84
  85         /* first check to see if we can still append to depend_tx */
  86         txd_lock(depend_tx);
  87         if (txd_parent(depend_tx) && depend_tx->chan == tx->chan) {
  88                 txd_chain(depend_tx, tx);
  89                 intr_tx = NULL;
  90         }
  91         txd_unlock(depend_tx);
  92
  93         /* attached dependency, flush the parent channel */
  94         if (!intr_tx) {
  95                 device->device_issue_pending(chan);
  96                 return;
  97         }
  98
  99         /* see if we can schedule an interrupt
 100          * otherwise poll for completion
 101          */
 102         if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 103                 intr_tx = device->device_prep_dma_interrupt(chan, 0);
 104         else
 105                 intr_tx = NULL;
 106
 107         if (intr_tx) {
 108                 intr_tx->callback = NULL;
 109                 intr_tx->callback_param = NULL;
 110                 /* safe to chain outside the lock since we know we are
 111                  * not submitted yet
 112                  */
 113                 txd_chain(intr_tx, tx);
 114
 115                 /* check if we need to append */
 116                 txd_lock(depend_tx);
 117                 if (txd_parent(depend_tx)) {
 118                         txd_chain(depend_tx, intr_tx);
 119                         async_tx_ack(intr_tx);
 120                         intr_tx = NULL;
 121                 }
 122                 txd_unlock(depend_tx);
 123
 124                 if (intr_tx) {
 125                         txd_clear_parent(intr_tx);
 126                         intr_tx->tx_submit(intr_tx);
 127                         async_tx_ack(intr_tx);
 128                 }
 129                 device->device_issue_pending(chan);
 130         } else {
 131                 if (dma_wait_for_async_tx(depend_tx) != DMA_COMPLETE)
 132                         panic("%s: DMA error waiting for depend_tx\n",
 133                               __func__);
 134                 tx->tx_submit(tx);
 135         }
 136 }
 137
 138
 139 /**
 140  * submit_disposition - flags for routing an incoming operation
 141  * @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
 142  * @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
 143  * @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
 144  *
 145  * while holding depend_tx->lock we must avoid submitting new operations
 146  * to prevent a circular locking dependency with drivers that already
 147  * hold a channel lock when calling async_tx_run_dependencies.
 148  */
 149 enum submit_disposition {
 150         ASYNC_TX_SUBMITTED,
 151         ASYNC_TX_CHANNEL_SWITCH,
 152         ASYNC_TX_DIRECT_SUBMIT,
 153 };
 154
 155 void
 156 async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
 157                 struct async_submit_ctl *submit)
 158 {
 159         struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
 160
 161         tx->callback = submit->cb_fn;
 162         tx->callback_param = submit->cb_param;
 163
 164         if (depend_tx) {
 165                 enum submit_disposition s;
 166
 167                 /* sanity check the dependency chain:
 168                  * 1/ if ack is already set then we cannot be sure
 169                  * we are referring to the correct operation
 170                  * 2/ dependencies are 1:1 i.e. two transactions can
 171                  * not depend on the same parent
 172                  */
 173                 BUG_ON(async_tx_test_ack(depend_tx) || txd_next(depend_tx) ||
 174                        txd_parent(tx));
 175
 176                 /* the lock prevents async_tx_run_dependencies from missing
 177                  * the setting of ->next when ->parent != NULL
 178                  */
 179                 txd_lock(depend_tx);
 180                 if (txd_parent(depend_tx)) {
 181                         /* we have a parent so we can not submit directly
 182                          * if we are staying on the same channel: append
 183                          * else: channel switch
 184                          */
 185                         if (depend_tx->chan == chan) {
 186                                 txd_chain(depend_tx, tx);
 187                                 s = ASYNC_TX_SUBMITTED;
 188                         } else
 189                                 s = ASYNC_TX_CHANNEL_SWITCH;
 190                 } else {
 191                         /* we do not have a parent so we may be able to submit
 192                          * directly if we are staying on the same channel
 193                          */
 194                         if (depend_tx->chan == chan)
 195                                 s = ASYNC_TX_DIRECT_SUBMIT;
 196                         else
 197                                 s = ASYNC_TX_CHANNEL_SWITCH;
 198                 }
 199                 txd_unlock(depend_tx);
 200
 201                 switch (s) {
 202                 case ASYNC_TX_SUBMITTED:
 203                         break;
 204                 case ASYNC_TX_CHANNEL_SWITCH:
 205                         async_tx_channel_switch(depend_tx, tx);
 206                         break;
 207                 case ASYNC_TX_DIRECT_SUBMIT:
 208                         txd_clear_parent(tx);
 209                         tx->tx_submit(tx);
 210                         break;
 211                 }
 212         } else {
 213                 txd_clear_parent(tx);
 214                 tx->tx_submit(tx);
 215         }
 216
 217         if (submit->flags & ASYNC_TX_ACK)
 218                 async_tx_ack(tx);
 219
 220         if (depend_tx)
 221                 async_tx_ack(depend_tx);
 222 }
 223 EXPORT_SYMBOL_GPL(async_tx_submit);
 224
 225 /**
 226  * async_trigger_callback - schedules the callback function to be run
 227  * @submit: submission and completion parameters
 228  *
 229  * honored flags: ASYNC_TX_ACK
 230  *
 231  * The callback is run after any dependent operations have completed.
 232  */
 233 struct dma_async_tx_descriptor *
 234 async_trigger_callback(struct async_submit_ctl *submit)
 235 {
 236         struct dma_chan *chan;
 237         struct dma_device *device;
 238         struct dma_async_tx_descriptor *tx;
 239         struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
 240
 241         if (depend_tx) {
 242                 chan = depend_tx->chan;
 243                 device = chan->device;
 244
 245                 /* see if we can schedule an interrupt
 246                  * otherwise poll for completion
 247                  */
 248                 if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 249                         device = NULL;
 250
 251                 tx = device ? device->device_prep_dma_interrupt(chan, 0) : NULL;
 252         } else
 253                 tx = NULL;
 254
 255         if (tx) {
 256                 pr_debug("%s: (async)\n", __func__);
 257
 258                 async_tx_submit(chan, tx, submit);
 259         } else {
 260                 pr_debug("%s: (sync)\n", __func__);
 261
 262                 /* wait for any prerequisite operations */
 263                 async_tx_quiesce(&submit->depend_tx);
 264
 265                 async_tx_sync_epilog(submit);
 266         }
 267
 268         return tx;
 269 }
 270 EXPORT_SYMBOL_GPL(async_trigger_callback);
 271
 272 /**
 273  * async_tx_quiesce - ensure tx is complete and freeable upon return
 274  * @tx - transaction to quiesce
 275  */
 276 void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
 277 {
 278         if (*tx) {
 279                 /* if ack is already set then we cannot be sure
 280                  * we are referring to the correct operation
 281                  */
 282                 BUG_ON(async_tx_test_ack(*tx));
 283                 if (dma_wait_for_async_tx(*tx) != DMA_COMPLETE)
 284                         panic("%s: DMA error waiting for transaction\n",
 285                               __func__);
 286                 async_tx_ack(*tx);
 287                 *tx = NULL;
 288         }
 289 }
 290 EXPORT_SYMBOL_GPL(async_tx_quiesce);
 291
 292 MODULE_AUTHOR("Intel Corporation");
 293 MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
 294 MODULE_LICENSE("GPL");