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DEFINITIONS
This source file includes following definitions.
- do_async_xor
- do_sync_xor
- async_xor
- page_is_zero
- async_xor_zero_sum
- async_xor_init
- async_xor_exit
/*
* 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_chan *chan, 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_device *dma = chan->device;
dma_addr_t *dma_src = (dma_addr_t *) src_list;
struct dma_async_tx_descriptor *tx = NULL;
int src_off = 0;
int i;
dma_async_tx_callback _cb_fn;
void *_cb_param;
enum async_tx_flags async_flags;
enum dma_ctrl_flags dma_flags;
int xor_src_cnt;
dma_addr_t dma_dest;
dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_FROM_DEVICE);
for (i = 0; i < src_cnt; i++)
dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
len, DMA_TO_DEVICE);
while (src_cnt) {
async_flags = flags;
dma_flags = 0;
xor_src_cnt = min(src_cnt, dma->max_xor);
/* if we are submitting additional xors, leave the chain open,
* clear the callback parameters, and leave the destination
* buffer mapped
*/
if (src_cnt > xor_src_cnt) {
async_flags &= ~ASYNC_TX_ACK;
dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
_cb_fn = NULL;
_cb_param = NULL;
} else {
_cb_fn = cb_fn;
_cb_param = cb_param;
}
if (_cb_fn)
dma_flags |= DMA_PREP_INTERRUPT;
/* 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 = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
xor_src_cnt, len, dma_flags);
if (unlikely(!tx))
async_tx_quiesce(&depend_tx);
/* spin wait for the preceeding transactions to complete */
while (unlikely(!tx)) {
dma_async_issue_pending(chan);
tx = dma->device_prep_dma_xor(chan, dma_dest,
&dma_src[src_off],
xor_src_cnt, len,
dma_flags);
}
async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
_cb_param);
depend_tx = tx;
flags |= ASYNC_TX_DEP_ACK;
if (src_cnt > xor_src_cnt) {
/* drop completed sources */
src_cnt -= xor_src_cnt;
src_off += xor_src_cnt;
/* use the intermediate result a source */
dma_src[--src_off] = dma_dest;
src_cnt++;
} else
break;
}
return tx;
}
static void
do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, enum async_tx_flags flags,
dma_async_tx_callback cb_fn, void *cb_param)
{
int i;
int xor_src_cnt;
int src_off = 0;
void *dest_buf;
void **srcs = (void **) src_list;
/* reuse the 'src_list' array to convert to buffer pointers */
for (i = 0; i < src_cnt; i++)
srcs[i] = page_address(src_list[i]) + offset;
/* set destination address */
dest_buf = page_address(dest) + offset;
if (flags & ASYNC_TX_XOR_ZERO_DST)
memset(dest_buf, 0, len);
while (src_cnt > 0) {
/* process up to 'MAX_XOR_BLOCKS' sources */
xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
/* drop completed sources */
src_cnt -= xor_src_cnt;
src_off += xor_src_cnt;
}
async_tx_sync_epilog(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);
BUG_ON(src_cnt <= 1);
if (chan) {
/* run the xor asynchronously */
pr_debug("%s (async): len: %zu\n", __func__, len);
return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
flags, depend_tx, cb_fn, cb_param);
} else {
/* run the xor synchronously */
pr_debug("%s (sync): len: %zu\n", __func__, len);
/* in the sync case the dest is an implied source
* (assumes the dest is the first source)
*/
if (flags & ASYNC_TX_XOR_DROP_DST) {
src_cnt--;
src_list++;
}
/* wait for any prerequisite operations */
async_tx_quiesce(&depend_tx);
do_sync_xor(dest, src_list, offset, src_cnt, len,
flags, cb_fn, cb_param);
return NULL;
}
}
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 && src_cnt <= device->max_xor) {
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 (unlikely(!tx)) {
async_tx_quiesce(&depend_tx);
while (!tx) {
dma_async_issue_pending(chan);
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);
async_tx_quiesce(&tx);
*result = page_is_zero(dest, offset, len) ? 0 : 1;
async_tx_sync_epilog(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");