1 /* 2 * copy offload engine support 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/kernel.h> 27 #include <linux/highmem.h> 28 #include <linux/mm.h> 29 #include <linux/dma-mapping.h> 30 #include <linux/async_tx.h> 31 32 /** 33 * async_memcpy - attempt to copy memory with a dma engine. 34 * @dest: destination page 35 * @src: src page 36 * @offset: offset in pages to start transaction 37 * @len: length in bytes 38 * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK, 39 * @depend_tx: memcpy depends on the result of this transaction 40 * @cb_fn: function to call when the memcpy completes 41 * @cb_param: parameter to pass to the callback routine 42 */ 43 struct dma_async_tx_descriptor * 44 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset, 45 unsigned int src_offset, size_t len, enum async_tx_flags flags, 46 struct dma_async_tx_descriptor *depend_tx, 47 dma_async_tx_callback cb_fn, void *cb_param) 48 { 49 struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_MEMCPY, 50 &dest, 1, &src, 1, len); 51 struct dma_device *device = chan ? chan->device : NULL; 52 struct dma_async_tx_descriptor *tx = NULL; 53 54 if (device) { 55 dma_addr_t dma_dest, dma_src; 56 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0; 57 58 dma_dest = dma_map_page(device->dev, dest, dest_offset, len, 59 DMA_FROM_DEVICE); 60 61 dma_src = dma_map_page(device->dev, src, src_offset, len, 62 DMA_TO_DEVICE); 63 64 tx = device->device_prep_dma_memcpy(chan, dma_dest, dma_src, 65 len, dma_prep_flags); 66 } 67 68 if (tx) { 69 pr_debug("%s: (async) len: %zu\n", __func__, len); 70 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); 71 } else { 72 void *dest_buf, *src_buf; 73 pr_debug("%s: (sync) len: %zu\n", __func__, len); 74 75 /* wait for any prerequisite operations */ 76 async_tx_quiesce(&depend_tx); 77 78 dest_buf = kmap_atomic(dest, KM_USER0) + dest_offset; 79 src_buf = kmap_atomic(src, KM_USER1) + src_offset; 80 81 memcpy(dest_buf, src_buf, len); 82 83 kunmap_atomic(dest_buf, KM_USER0); 84 kunmap_atomic(src_buf, KM_USER1); 85 86 async_tx_sync_epilog(cb_fn, cb_param); 87 } 88 89 return tx; 90 } 91 EXPORT_SYMBOL_GPL(async_memcpy); 92 93 static int __init async_memcpy_init(void) 94 { 95 return 0; 96 } 97 98 static void __exit async_memcpy_exit(void) 99 { 100 do { } while (0); 101 } 102 103 module_init(async_memcpy_init); 104 module_exit(async_memcpy_exit); 105 106 MODULE_AUTHOR("Intel Corporation"); 107 MODULE_DESCRIPTION("asynchronous memcpy api"); 108 MODULE_LICENSE("GPL"); 109