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