/*
* Copyright(c) 2007 Yuri Tikhonov <yur@emcraft.com>
* Copyright(c) 2009 Intel Corporation
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that 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., 59
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* The full GNU General Public License is included in this distribution in the
* file called COPYING.
*/
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <linux/raid/pq.h>
#include <linux/async_tx.h>
/**
* pq_scribble_page - space to hold throwaway P or Q buffer for
* synchronous gen_syndrome
*/
static struct page *pq_scribble_page;
/* the struct page *blocks[] parameter passed to async_gen_syndrome()
* and async_syndrome_val() contains the 'P' destination address at
* blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
*
* note: these are macros as they are used as lvalues
*/
#define P(b, d) (b[d-2])
#define Q(b, d) (b[d-1])
/**
* do_async_gen_syndrome - asynchronously calculate P and/or Q
*/
static __async_inline struct dma_async_tx_descriptor *
do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
const unsigned char *scfs, unsigned int offset, int disks,
size_t len, dma_addr_t *dma_src,
struct async_submit_ctl *submit)
{
struct dma_async_tx_descriptor *tx = NULL;
struct dma_device *dma = chan->device;
enum dma_ctrl_flags dma_flags = 0;
enum async_tx_flags flags_orig = submit->flags;
dma_async_tx_callback cb_fn_orig = submit->cb_fn;
dma_async_tx_callback cb_param_orig = submit->cb_param;
int src_cnt = disks - 2;
unsigned char coefs[src_cnt];
unsigned short pq_src_cnt;
dma_addr_t dma_dest[2];
int src_off = 0;
int idx;
int i;
/* DMAs use destinations as sources, so use BIDIRECTIONAL mapping */
if (P(blocks, disks))
dma_dest[0] = dma_map_page(dma->dev, P(blocks, disks), offset,
len, DMA_BIDIRECTIONAL);
else
dma_flags |= DMA_PREP_PQ_DISABLE_P;
if (Q(blocks, disks))
dma_dest[1] = dma_map_page(dma->dev, Q(blocks, disks), offset,
len, DMA_BIDIRECTIONAL);
else
dma_flags |= DMA_PREP_PQ_DISABLE_Q;
/* convert source addresses being careful to collapse 'empty'
* sources and update the coefficients accordingly
*/
for (i = 0, idx = 0; i < src_cnt; i++) {
if (blocks[i] == NULL)
continue;
dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
DMA_TO_DEVICE);
coefs[idx] = scfs[i];
idx++;
}
src_cnt = idx;
while (src_cnt > 0) {
submit->flags = flags_orig;
pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
/* if we are submitting additional pqs, leave the chain open,
* clear the callback parameters, and leave the destination
* buffers mapped
*/
if (src_cnt > pq_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 {
dma_flags &= ~DMA_COMPL_SKIP_DEST_UNMAP;
submit->cb_fn = cb_fn_orig;
submit->cb_param = cb_param_orig;
if (cb_fn_orig)
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
*/
for (;;) {
tx = dma->device_prep_dma_pq(chan, dma_dest,
&dma_src[src_off],
pq_src_cnt,
&coefs[src_off], len,
dma_flags);
if (likely(tx))
break;
async_tx_quiesce(&submit->depend_tx);
dma_async_issue_pending(chan);
}
async_tx_submit(chan, tx, submit);
submit->depend_tx = tx;
/* drop completed sources */
src_cnt -= pq_src_cnt;
src_off += pq_src_cnt;
dma_flags |= DMA_PREP_CONTINUE;
}
return tx;
}
/**
* do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
*/
static void
do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
size_t len, struct async_submit_ctl *submit)
{
void **srcs;
int i;
if (submit->scribble)
srcs = submit->scribble;
else
srcs = (void **) blocks;
for (i = 0; i < disks; i++) {
if (blocks[i] == NULL) {
BUG_ON(i > disks - 3); /* P or Q can't be zero */
srcs[i] = (void*)raid6_empty_zero_page;
} else
srcs[i] = page_address(blocks[i]) + offset;
}
raid6_call.gen_syndrome(disks, len, srcs);
async_tx_sync_epilog(submit);
}
/**
* async_gen_syndrome - asynchronously calculate a raid6 syndrome
* @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
* @offset: common offset into each block (src and dest) to start transaction
* @disks: number of blocks (including missing P or Q, see below)
* @len: length of operation in bytes
* @submit: submission/completion modifiers
*
* General note: This routine assumes a field of GF(2^8) with a
* primitive polynomial of 0x11d and a generator of {02}.
*
* 'disks' note: callers can optionally omit either P or Q (but not
* both) from the calculation by setting blocks[disks-2] or
* blocks[disks-1] to NULL. When P or Q is omitted 'len' must be <=
* PAGE_SIZE as a temporary buffer of this size is used in the
* synchronous path. 'disks' always accounts for both destination
* buffers. If any source buffers (blocks[i] where i < disks - 2) are
* set to NULL those buffers will be replaced with the raid6_zero_page
* in the synchronous path and omitted in the hardware-asynchronous
* path.
*
* 'blocks' note: if submit->scribble is NULL then the contents of
* 'blocks' may be overwritten to perform address conversions
* (dma_map_page() or page_address()).
*/
struct dma_async_tx_descriptor *
async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
size_t len, struct async_submit_ctl *submit)
{
int src_cnt = disks - 2;
struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
&P(blocks, disks), 2,
blocks, src_cnt, len);
struct dma_device *device = chan ? chan->device : NULL;
dma_addr_t *dma_src = NULL;
BUG_ON(disks > 255 || !(P(blocks, disks) || Q(blocks, disks)));
if (submit->scribble)
dma_src = submit->scribble;
else if (sizeof(dma_addr_t) <= sizeof(struct page *))
dma_src = (dma_addr_t *) blocks;
if (dma_src && device &&
(src_cnt <= dma_maxpq(device, 0) ||
dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
is_dma_pq_aligned(device, offset, 0, len)) {
/* run the p+q asynchronously */
pr_debug("%s: (async) disks: %d len: %zu\n",
__func__, disks, len);
return do_async_gen_syndrome(chan, blocks, raid6_gfexp, offset,
disks, len, dma_src, submit);
}
/* run the pq synchronously */
pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
/* wait for any prerequisite operations */
async_tx_quiesce(&submit->depend_tx);
if (!P(blocks, disks)) {
P(blocks, disks) = pq_scribble_page;
BUG_ON(len + offset > PAGE_SIZE);
}
if (!Q(blocks, disks)) {
Q(blocks, disks) = pq_scribble_page;
BUG_ON(len + offset > PAGE_SIZE);
}
do_sync_gen_syndrome(blocks, offset, disks, len, submit);
return NULL;
}
EXPORT_SYMBOL_GPL(async_gen_syndrome);
static inline struct dma_chan *
pq_val_chan(struct async_submit_ctl *submit, struct page **blocks, int disks, size_t len)
{
#ifdef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
return NULL;
#endif
return async_tx_find_channel(submit, DMA_PQ_VAL, NULL, 0, blocks,
disks, len);
}
/**
* async_syndrome_val - asynchronously validate a raid6 syndrome
* @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
* @offset: common offset into each block (src and dest) to start transaction
* @disks: number of blocks (including missing P or Q, see below)
* @len: length of operation in bytes
* @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
* @spare: temporary result buffer for the synchronous case
* @submit: submission / completion modifiers
*
* The same notes from async_gen_syndrome apply to the 'blocks',
* and 'disks' parameters of this routine. The synchronous path
* requires a temporary result buffer and submit->scribble to be
* specified.
*/
struct dma_async_tx_descriptor *
async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
size_t len, enum sum_check_flags *pqres, struct page *spare,
struct async_submit_ctl *submit)
{
struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx;
unsigned char coefs[disks-2];
enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
dma_addr_t *dma_src = NULL;
int src_cnt = 0;
BUG_ON(disks < 4);
if (submit->scribble)
dma_src = submit->scribble;
else if (sizeof(dma_addr_t) <= sizeof(struct page *))
dma_src = (dma_addr_t *) blocks;
if (dma_src && device && disks <= dma_maxpq(device, 0) &&
is_dma_pq_aligned(device, offset, 0, len)) {
struct device *dev = device->dev;
dma_addr_t *pq = &dma_src[disks-2];
int i;
pr_debug("%s: (async) disks: %d len: %zu\n",
__func__, disks, len);
if (!P(blocks, disks))
dma_flags |= DMA_PREP_PQ_DISABLE_P;
else
pq[0] = dma_map_page(dev, P(blocks, disks),
offset, len,
DMA_TO_DEVICE);
if (!Q(blocks, disks))
dma_flags |= DMA_PREP_PQ_DISABLE_Q;
else
pq[1] = dma_map_page(dev, Q(blocks, disks),
offset, len,
DMA_TO_DEVICE);
if (submit->flags & ASYNC_TX_FENCE)
dma_flags |= DMA_PREP_FENCE;
for (i = 0; i < disks-2; i++)
if (likely(blocks[i])) {
dma_src[src_cnt] = dma_map_page(dev, blocks[i],
offset, len,
DMA_TO_DEVICE);
coefs[src_cnt] = raid6_gfexp[i];
src_cnt++;
}
for (;;) {
tx = device->device_prep_dma_pq_val(chan, pq, dma_src,
src_cnt,
coefs,
len, pqres,
dma_flags);
if (likely(tx))
break;
async_tx_quiesce(&submit->depend_tx);
dma_async_issue_pending(chan);
}
async_tx_submit(chan, tx, submit);
return tx;
} else {
struct page *p_src = P(blocks, disks);
struct page *q_src = Q(blocks, disks);
enum async_tx_flags flags_orig = submit->flags;
dma_async_tx_callback cb_fn_orig = submit->cb_fn;
void *scribble = submit->scribble;
void *cb_param_orig = submit->cb_param;
void *p, *q, *s;
pr_debug("%s: (sync) disks: %d len: %zu\n",
__func__, disks, len);
/* caller must provide a temporary result buffer and
* allow the input parameters to be preserved
*/
BUG_ON(!spare || !scribble);
/* wait for any prerequisite operations */
async_tx_quiesce(&submit->depend_tx);
/* recompute p and/or q into the temporary buffer and then
* check to see the result matches the current value
*/
tx = NULL;
*pqres = 0;
if (p_src) {
init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
NULL, NULL, scribble);
tx = async_xor(spare, blocks, offset, disks-2, len, submit);
async_tx_quiesce(&tx);
p = page_address(p_src) + offset;
s = page_address(spare) + offset;
*pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
}
if (q_src) {
P(blocks, disks) = NULL;
Q(blocks, disks) = spare;
init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
tx = async_gen_syndrome(blocks, offset, disks, len, submit);
async_tx_quiesce(&tx);
q = page_address(q_src) + offset;
s = page_address(spare) + offset;
*pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
}
/* restore P, Q and submit */
P(blocks, disks) = p_src;
Q(blocks, disks) = q_src;
submit->cb_fn = cb_fn_orig;
submit->cb_param = cb_param_orig;
submit->flags = flags_orig;
async_tx_sync_epilog(submit);
return NULL;
}
}
EXPORT_SYMBOL_GPL(async_syndrome_val);
static int __init async_pq_init(void)
{
pq_scribble_page = alloc_page(GFP_KERNEL);
if (pq_scribble_page)
return 0;
pr_err("%s: failed to allocate required spare page\n", __func__);
return -ENOMEM;
}
static void __exit async_pq_exit(void)
{
put_page(pq_scribble_page);
}
module_init(async_pq_init);
module_exit(async_pq_exit);
MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
MODULE_LICENSE("GPL");
