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"); 295