/* * xor offload engine api * * Copyright © 2006, Intel Corporation. * * Dan Williams <dan.j.williams@intel.com> * * with architecture considerations by: * Neil Brown <neilb@suse.de> * Jeff Garzik <jeff@garzik.org> * * This program is free software; you can redistribute it and/or modify it * under the terms and conditions of the GNU General Public License, * version 2, as published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. * */ #include <linux/kernel.h> #include <linux/interrupt.h> #include <linux/mm.h> #include <linux/dma-mapping.h> #include <linux/raid/xor.h> #include <linux/async_tx.h> /* do_async_xor - dma map the pages and perform the xor with an engine. * This routine is marked __always_inline so it can be compiled away * when CONFIG_DMA_ENGINE=n */ static __always_inline struct dma_async_tx_descriptor * do_async_xor(struct dma_device *device, struct dma_chan *chan, struct page *dest, struct page **src_list, unsigned int offset, unsigned int src_cnt, size_t len, enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { dma_addr_t dma_dest; dma_addr_t *dma_src = (dma_addr_t *) src_list; struct dma_async_tx_descriptor *tx; int i; unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0; pr_debug("%s: len: %zu\n", __func__, len); dma_dest = dma_map_page(device->dev, dest, offset, len, DMA_FROM_DEVICE); for (i = 0; i < src_cnt; i++) dma_src[i] = dma_map_page(device->dev, src_list[i], offset, len, DMA_TO_DEVICE); /* Since we have clobbered the src_list we are committed * to doing this asynchronously. Drivers force forward progress * in case they can not provide a descriptor */ tx = device->device_prep_dma_xor(chan, dma_dest, dma_src, src_cnt, len, dma_prep_flags); if (!tx) { if (depend_tx) dma_wait_for_async_tx(depend_tx); while (!tx) tx = device->device_prep_dma_xor(chan, dma_dest, dma_src, src_cnt, len, dma_prep_flags); } async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); return tx; } static void do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, unsigned int src_cnt, size_t len, enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { void *_dest; int i; pr_debug("%s: len: %zu\n", __func__, len); /* reuse the 'src_list' array to convert to buffer pointers */ for (i = 0; i < src_cnt; i++) src_list[i] = (struct page *) (page_address(src_list[i]) + offset); /* set destination address */ _dest = page_address(dest) + offset; if (flags & ASYNC_TX_XOR_ZERO_DST) memset(_dest, 0, len); xor_blocks(src_cnt, len, _dest, (void **) src_list); async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); } /** * async_xor - attempt to xor a set of blocks with a dma engine. * xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST * flag must be set to not include dest data in the calculation. The * assumption with dma eninges is that they only use the destination * buffer as a source when it is explicity specified in the source list. * @dest: destination page * @src_list: array of source pages (if the dest is also a source it must be * at index zero). The contents of this array may be overwritten. * @offset: offset in pages to start transaction * @src_cnt: number of source pages * @len: length in bytes * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST, * ASYNC_TX_ACK, ASYNC_TX_DEP_ACK * @depend_tx: xor depends on the result of this transaction. * @cb_fn: function to call when the xor completes * @cb_param: parameter to pass to the callback routine */ struct dma_async_tx_descriptor * async_xor(struct page *dest, struct page **src_list, unsigned int offset, int src_cnt, size_t len, enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR, &dest, 1, src_list, src_cnt, len); struct dma_device *device = chan ? chan->device : NULL; struct dma_async_tx_descriptor *tx = NULL; dma_async_tx_callback _cb_fn; void *_cb_param; unsigned long local_flags; int xor_src_cnt; int i = 0, src_off = 0; BUG_ON(src_cnt <= 1); while (src_cnt) { local_flags = flags; if (device) { /* run the xor asynchronously */ xor_src_cnt = min(src_cnt, device->max_xor); /* if we are submitting additional xors * only set the callback on the last transaction */ if (src_cnt > xor_src_cnt) { local_flags &= ~ASYNC_TX_ACK; _cb_fn = NULL; _cb_param = NULL; } else { _cb_fn = cb_fn; _cb_param = cb_param; } tx = do_async_xor(device, chan, dest, &src_list[src_off], offset, xor_src_cnt, len, local_flags, depend_tx, _cb_fn, _cb_param); } else { /* run the xor synchronously */ /* in the sync case the dest is an implied source * (assumes the dest is at the src_off index) */ if (flags & ASYNC_TX_XOR_DROP_DST) { src_cnt--; src_off++; } /* process up to 'MAX_XOR_BLOCKS' sources */ xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); /* if we are submitting additional xors * only set the callback on the last transaction */ if (src_cnt > xor_src_cnt) { local_flags &= ~ASYNC_TX_ACK; _cb_fn = NULL; _cb_param = NULL; } else { _cb_fn = cb_fn; _cb_param = cb_param; } /* wait for any prerequisite operations */ if (depend_tx) { /* if ack is already set then we cannot be sure * we are referring to the correct operation */ BUG_ON(depend_tx->ack); if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR) panic("%s: DMA_ERROR waiting for " "depend_tx\n", __func__); } do_sync_xor(dest, &src_list[src_off], offset, xor_src_cnt, len, local_flags, depend_tx, _cb_fn, _cb_param); } /* the previous tx is hidden from the client, * so ack it */ if (i && depend_tx) async_tx_ack(depend_tx); depend_tx = tx; if (src_cnt > xor_src_cnt) { /* drop completed sources */ src_cnt -= xor_src_cnt; src_off += xor_src_cnt; /* unconditionally preserve the destination */ flags &= ~ASYNC_TX_XOR_ZERO_DST; /* use the intermediate result a source, but remember * it's dropped, because it's implied, in the sync case */ src_list[--src_off] = dest; src_cnt++; flags |= ASYNC_TX_XOR_DROP_DST; } else src_cnt = 0; i++; } return tx; } EXPORT_SYMBOL_GPL(async_xor); static int page_is_zero(struct page *p, unsigned int offset, size_t len) { char *a = page_address(p) + offset; return ((*(u32 *) a) == 0 && memcmp(a, a + 4, len - 4) == 0); } /** * async_xor_zero_sum - attempt a xor parity check with a dma engine. * @dest: destination page used if the xor is performed synchronously * @src_list: array of source pages. The dest page must be listed as a source * at index zero. The contents of this array may be overwritten. * @offset: offset in pages to start transaction * @src_cnt: number of source pages * @len: length in bytes * @result: 0 if sum == 0 else non-zero * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK * @depend_tx: xor depends on the result of this transaction. * @cb_fn: function to call when the xor completes * @cb_param: parameter to pass to the callback routine */ struct dma_async_tx_descriptor * async_xor_zero_sum(struct page *dest, struct page **src_list, unsigned int offset, int src_cnt, size_t len, u32 *result, enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM, &dest, 1, src_list, src_cnt, len); struct dma_device *device = chan ? chan->device : NULL; struct dma_async_tx_descriptor *tx = NULL; BUG_ON(src_cnt <= 1); if (device) { dma_addr_t *dma_src = (dma_addr_t *) src_list; unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0; int i; pr_debug("%s: (async) len: %zu\n", __func__, len); for (i = 0; i < src_cnt; i++) dma_src[i] = dma_map_page(device->dev, src_list[i], offset, len, DMA_TO_DEVICE); tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt, len, result, dma_prep_flags); if (!tx) { if (depend_tx) dma_wait_for_async_tx(depend_tx); while (!tx) tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt, len, result, dma_prep_flags); } async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); } else { unsigned long xor_flags = flags; pr_debug("%s: (sync) len: %zu\n", __func__, len); xor_flags |= ASYNC_TX_XOR_DROP_DST; xor_flags &= ~ASYNC_TX_ACK; tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags, depend_tx, NULL, NULL); if (tx) { if (dma_wait_for_async_tx(tx) == DMA_ERROR) panic("%s: DMA_ERROR waiting for tx\n", __func__); async_tx_ack(tx); } *result = page_is_zero(dest, offset, len) ? 0 : 1; tx = NULL; async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); } return tx; } EXPORT_SYMBOL_GPL(async_xor_zero_sum); static int __init async_xor_init(void) { #ifdef CONFIG_DMA_ENGINE /* To conserve stack space the input src_list (array of page pointers) * is reused to hold the array of dma addresses passed to the driver. * This conversion is only possible when dma_addr_t is less than the * the size of a pointer. HIGHMEM64G is known to violate this * assumption. */ BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *)); #endif return 0; } static void __exit async_xor_exit(void) { do { } while (0); } module_init(async_xor_init); module_exit(async_xor_exit); MODULE_AUTHOR("Intel Corporation"); MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); MODULE_LICENSE("GPL");