1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * copy offload engine support 4 * 5 * Copyright © 2006, Intel Corporation. 6 * 7 * Dan Williams <dan.j.williams@intel.com> 8 * 9 * with architecture considerations by: 10 * Neil Brown <neilb@suse.de> 11 * Jeff Garzik <jeff@garzik.org> 12 */ 13 #include <linux/kernel.h> 14 #include <linux/highmem.h> 15 #include <linux/module.h> 16 #include <linux/mm.h> 17 #include <linux/dma-mapping.h> 18 #include <linux/async_tx.h> 19 20 /** 21 * async_memcpy - attempt to copy memory with a dma engine. 22 * @dest: destination page 23 * @src: src page 24 * @dest_offset: offset into 'dest' to start transaction 25 * @src_offset: offset into 'src' to start transaction 26 * @len: length in bytes 27 * @submit: submission / completion modifiers 28 * 29 * honored flags: ASYNC_TX_ACK 30 */ 31 struct dma_async_tx_descriptor * 32 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset, 33 unsigned int src_offset, size_t len, 34 struct async_submit_ctl *submit) 35 { 36 struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMCPY, 37 &dest, 1, &src, 1, len); 38 struct dma_device *device = chan ? chan->device : NULL; 39 struct dma_async_tx_descriptor *tx = NULL; 40 struct dmaengine_unmap_data *unmap = NULL; 41 42 if (device) 43 unmap = dmaengine_get_unmap_data(device->dev, 2, GFP_NOWAIT); 44 45 if (unmap && is_dma_copy_aligned(device, src_offset, dest_offset, len)) { 46 unsigned long dma_prep_flags = 0; 47 48 if (submit->cb_fn) 49 dma_prep_flags |= DMA_PREP_INTERRUPT; 50 if (submit->flags & ASYNC_TX_FENCE) 51 dma_prep_flags |= DMA_PREP_FENCE; 52 53 unmap->to_cnt = 1; 54 unmap->addr[0] = dma_map_page(device->dev, src, src_offset, len, 55 DMA_TO_DEVICE); 56 unmap->from_cnt = 1; 57 unmap->addr[1] = dma_map_page(device->dev, dest, dest_offset, len, 58 DMA_FROM_DEVICE); 59 unmap->len = len; 60 61 tx = device->device_prep_dma_memcpy(chan, unmap->addr[1], 62 unmap->addr[0], len, 63 dma_prep_flags); 64 } 65 66 if (tx) { 67 pr_debug("%s: (async) len: %zu\n", __func__, len); 68 69 dma_set_unmap(tx, unmap); 70 async_tx_submit(chan, tx, submit); 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(&submit->depend_tx); 77 78 dest_buf = kmap_atomic(dest) + dest_offset; 79 src_buf = kmap_atomic(src) + src_offset; 80 81 memcpy(dest_buf, src_buf, len); 82 83 kunmap_atomic(src_buf); 84 kunmap_atomic(dest_buf); 85 86 async_tx_sync_epilog(submit); 87 } 88 89 dmaengine_unmap_put(unmap); 90 91 return tx; 92 } 93 EXPORT_SYMBOL_GPL(async_memcpy); 94 95 MODULE_AUTHOR("Intel Corporation"); 96 MODULE_DESCRIPTION("asynchronous memcpy api"); 97 MODULE_LICENSE("GPL"); 98