/*
* 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 */
static __async_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, dma_addr_t *dma_src,
struct async_submit_ctl *submit)
{
struct dma_device *dma = chan->device;
struct dma_async_tx_descriptor *tx = NULL;
int src_off = 0;
int i;
dma_async_tx_callback cb_fn_orig = submit->cb_fn;
void *cb_param_orig = submit->cb_param;
enum async_tx_flags flags_orig = submit->flags;
enum dma_ctrl_flags dma_flags;
int xor_src_cnt;
dma_addr_t dma_dest;
/* map the dest bidrectional in case it is re-used as a source */
dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
for (i = 0; i < src_cnt; i++) {
/* only map the dest once */
if (unlikely(src_list[i] == dest)) {
dma_src[i] = dma_dest;
continue;
}
dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
len, DMA_TO_DEVICE);
}
while (src_cnt) {
submit->flags = flags_orig;
dma_flags = 0;
xor_src_cnt = min(src_cnt, (int)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) {
submit->flags &= ~ASYNC_TX_ACK;
submit->flags |= ASYNC_TX_FENCE;
dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
submit->cb_fn = NULL;
submit->cb_param = NULL;
} else {
submit->cb_fn = cb_fn_orig;
submit->cb_param = cb_param_orig;
}
if (submit->cb_fn)
dma_flags |= DMA_PREP_INTERRUPT;
if (submit->flags & ASYNC_TX_FENCE)
dma_flags |= DMA_PREP_FENCE;
/* 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(&submit->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, submit);
submit->depend_tx = tx;
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, struct async_submit_ctl *submit)
{
int i;
int xor_src_cnt;
int src_off = 0;
void *dest_buf;
void **srcs;
if (submit->scribble)
srcs = submit->scribble;
else
srcs = (void **) src_list;
/* 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 (submit->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(submit);
}
/**
* async_xor - attempt to xor a set of blocks with a dma engine.
* @dest: destination page
* @src_list: array of source pages
* @offset: common src/dst offset to start transaction
* @src_cnt: number of source pages
* @len: length in bytes
* @submit: submission / completion modifiers
*
* honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
*
* 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.
*
* src_list note: if the dest is also a source it must be at index zero.
* The contents of this array will be overwritten if a scribble region
* is not specified.
*/
struct dma_async_tx_descriptor *
async_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, struct async_submit_ctl *submit)
{
struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
&dest, 1, src_list,
src_cnt, len);
dma_addr_t *dma_src = NULL;
BUG_ON(src_cnt <= 1);
if (submit->scribble)
dma_src = submit->scribble;
else if (sizeof(dma_addr_t) <= sizeof(struct page *))
dma_src = (dma_addr_t *) src_list;
if (dma_src && chan && is_dma_xor_aligned(chan->device, offset, 0, len)) {
/* 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,
dma_src, submit);
} else {
/* run the xor synchronously */
pr_debug("%s (sync): len: %zu\n", __func__, len);
WARN_ONCE(chan, "%s: no space for dma address conversion\n",
__func__);
/* in the sync case the dest is an implied source
* (assumes the dest is the first source)
*/
if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
src_cnt--;
src_list++;
}
/* wait for any prerequisite operations */
async_tx_quiesce(&submit->depend_tx);
do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
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_val - 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
* @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
* @submit: submission / completion modifiers
*
* honored flags: ASYNC_TX_ACK
*
* src_list note: if the dest is also a source it must be at index zero.
* The contents of this array will be overwritten if a scribble region
* is not specified.
*/
struct dma_async_tx_descriptor *
async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, enum sum_check_flags *result,
struct async_submit_ctl *submit)
{
struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR_VAL,
&dest, 1, src_list,
src_cnt, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx = NULL;
dma_addr_t *dma_src = NULL;
BUG_ON(src_cnt <= 1);
if (submit->scribble)
dma_src = submit->scribble;
else if (sizeof(dma_addr_t) <= sizeof(struct page *))
dma_src = (dma_addr_t *) src_list;
if (dma_src && device && src_cnt <= device->max_xor &&
is_dma_xor_aligned(device, offset, 0, len)) {
unsigned long dma_prep_flags = 0;
int i;
pr_debug("%s: (async) len: %zu\n", __func__, len);
if (submit->cb_fn)
dma_prep_flags |= DMA_PREP_INTERRUPT;
if (submit->flags & ASYNC_TX_FENCE)
dma_prep_flags |= DMA_PREP_FENCE;
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_xor_val(chan, dma_src, src_cnt,
len, result,
dma_prep_flags);
if (unlikely(!tx)) {
async_tx_quiesce(&submit->depend_tx);
while (!tx) {
dma_async_issue_pending(chan);
tx = device->device_prep_dma_xor_val(chan,
dma_src, src_cnt, len, result,
dma_prep_flags);
}
}
async_tx_submit(chan, tx, submit);
} else {
enum async_tx_flags flags_orig = submit->flags;
pr_debug("%s: (sync) len: %zu\n", __func__, len);
WARN_ONCE(device && src_cnt <= device->max_xor,
"%s: no space for dma address conversion\n",
__func__);
submit->flags |= ASYNC_TX_XOR_DROP_DST;
submit->flags &= ~ASYNC_TX_ACK;
tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
async_tx_quiesce(&tx);
*result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
async_tx_sync_epilog(submit);
submit->flags = flags_orig;
}
return tx;
}
EXPORT_SYMBOL_GPL(async_xor_val);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
MODULE_LICENSE("GPL");
