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NTB: Use DMA Engine to Transmit and Receive 

Allocate and use a DMA engine channel to transmit and receive data over
NTB.  If none is allocated, fall back to using the CPU to transfer data.

Signed-off-by: Jon Mason <jon.mason@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Jon Mason 2013-02-12 09:52:50 -07:00
parent ac477afb04
commit 282a2feeb9
3 changed files with 298 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/ntb/ntb_hw.c
View File

@ -349,6 +349,23 @@ int ntb_read_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 *val)
return 0;
}
/**
* ntb_get_mw_base() - get addr for the NTB memory window
* @ndev: pointer to ntb_device instance
* @mw: memory window number
*
* This function provides the base address of the memory window specified.
*
* RETURNS: address, or NULL on error.
*/
resource_size_t ntb_get_mw_base(struct ntb_device *ndev, unsigned int mw)
{
if (mw >= ntb_max_mw(ndev))
return 0;
return pci_resource_start(ndev->pdev, MW_TO_BAR(mw));
}
/**
* ntb_get_mw_vbase() - get virtual addr for the NTB memory window
* @ndev: pointer to ntb_device instance

1
drivers/ntb/ntb_hw.h
View File

@ -240,6 +240,7 @@ int ntb_write_local_spad(struct ntb_device *ndev, unsigned int idx, u32 val);
int ntb_read_local_spad(struct ntb_device *ndev, unsigned int idx, u32 *val);
int ntb_write_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 val);
int ntb_read_remote_spad(struct ntb_device *ndev, unsigned int idx, u32 *val);
resource_size_t ntb_get_mw_base(struct ntb_device *ndev, unsigned int mw);
void __iomem *ntb_get_mw_vbase(struct ntb_device *ndev, unsigned int mw);
u64 ntb_get_mw_size(struct ntb_device *ndev, unsigned int mw);
void ntb_ring_sdb(struct ntb_device *ndev, unsigned int idx);

330
drivers/ntb/ntb_transport.c
View File

@ -47,6 +47,7 @@
*/
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/export.h>
@ -68,6 +69,10 @@ static unsigned char max_num_clients;
module_param(max_num_clients, byte, 0644);
MODULE_PARM_DESC(max_num_clients, "Maximum number of NTB transport clients");
static unsigned int copy_bytes = 1024;
module_param(copy_bytes, uint, 0644);
MODULE_PARM_DESC(copy_bytes, "Threshold under which NTB will use the CPU to copy instead of DMA");
struct ntb_queue_entry {
/* ntb_queue list reference */
struct list_head entry;
@ -76,6 +81,13 @@ struct ntb_queue_entry {
void *buf;
unsigned int len;
unsigned int flags;
struct ntb_transport_qp *qp;
union {
struct ntb_payload_header __iomem *tx_hdr;
struct ntb_payload_header *rx_hdr;
};
unsigned int index;
};
struct ntb_rx_info {
@ -86,6 +98,7 @@ struct ntb_transport_qp {
struct ntb_transport *transport;
struct ntb_device *ndev;
void *cb_data;
struct dma_chan *dma_chan;
bool client_ready;
bool qp_link;
@ -99,6 +112,7 @@ struct ntb_transport_qp {
struct list_head tx_free_q;
spinlock_t ntb_tx_free_q_lock;
void __iomem *tx_mw;
dma_addr_t tx_mw_phys;
unsigned int tx_index;
unsigned int tx_max_entry;
unsigned int tx_max_frame;
@ -114,6 +128,7 @@ struct ntb_transport_qp {
unsigned int rx_index;
unsigned int rx_max_entry;
unsigned int rx_max_frame;
dma_cookie_t last_cookie;
void (*event_handler) (void *data, int status);
struct delayed_work link_work;
@ -129,9 +144,14 @@ struct ntb_transport_qp {
u64 rx_err_no_buf;
u64 rx_err_oflow;
u64 rx_err_ver;
u64 rx_memcpy;
u64 rx_async;
u64 tx_bytes;
u64 tx_pkts;
u64 tx_ring_full;
u64 tx_err_no_buf;
u64 tx_memcpy;
u64 tx_async;
};
struct ntb_transport_mw {
@ -381,7 +401,7 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
char *buf;
ssize_t ret, out_offset, out_count;
out_count = 600;
out_count = 1000;
buf = kmalloc(out_count, GFP_KERNEL);
if (!buf)
@ -395,6 +415,10 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
"rx_bytes - \t%llu\n", qp->rx_bytes);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"rx_pkts - \t%llu\n", qp->rx_pkts);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"rx_memcpy - \t%llu\n", qp->rx_memcpy);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"rx_async - \t%llu\n", qp->rx_async);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"rx_ring_empty - %llu\n", qp->rx_ring_empty);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
@ -414,8 +438,14 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
"tx_bytes - \t%llu\n", qp->tx_bytes);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_pkts - \t%llu\n", qp->tx_pkts);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_memcpy - \t%llu\n", qp->tx_memcpy);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_async - \t%llu\n", qp->tx_async);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_ring_full - \t%llu\n", qp->tx_ring_full);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_err_no_buf - %llu\n", qp->tx_err_no_buf);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_mw - \t%p\n", qp->tx_mw);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
@ -488,11 +518,11 @@ static void ntb_transport_setup_qp_mw(struct ntb_transport *nt,
num_qps_mw = nt->max_qps / mw_max;
rx_size = (unsigned int) nt->mw[mw_num].size / num_qps_mw;
qp->remote_rx_info = nt->mw[mw_num].virt_addr +
(qp_num / mw_max * rx_size);
qp->rx_buff = nt->mw[mw_num].virt_addr + qp_num / mw_max * rx_size;
rx_size -= sizeof(struct ntb_rx_info);
qp->rx_buff = qp->remote_rx_info + 1;
qp->remote_rx_info = qp->rx_buff + rx_size;
/* Due to housekeeping, there must be atleast 2 buffs */
qp->rx_max_frame = min(transport_mtu, rx_size / 2);
qp->rx_max_entry = rx_size / qp->rx_max_frame;
@ -796,12 +826,13 @@ static void ntb_qp_link_work(struct work_struct *work)
msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
}
static void ntb_transport_init_queue(struct ntb_transport *nt,
static int ntb_transport_init_queue(struct ntb_transport *nt,
unsigned int qp_num)
{
struct ntb_transport_qp *qp;
unsigned int num_qps_mw, tx_size;
u8 mw_num, mw_max;
u64 qp_offset;
mw_max = ntb_max_mw(nt->ndev);
mw_num = QP_TO_MW(nt->ndev, qp_num);
@ -820,11 +851,18 @@ static void ntb_transport_init_queue(struct ntb_transport *nt,
num_qps_mw = nt->max_qps / mw_max;
tx_size = (unsigned int) ntb_get_mw_size(qp->ndev, mw_num) / num_qps_mw;
qp->rx_info = ntb_get_mw_vbase(nt->ndev, mw_num) +
(qp_num / mw_max * tx_size);
tx_size -= sizeof(struct ntb_rx_info);
qp_offset = qp_num / mw_max * tx_size;
qp->tx_mw = ntb_get_mw_vbase(nt->ndev, mw_num) + qp_offset;
if (!qp->tx_mw)
return -EINVAL;
qp->tx_mw_phys = ntb_get_mw_base(qp->ndev, mw_num) + qp_offset;
if (!qp->tx_mw_phys)
return -EINVAL;
tx_size -= sizeof(struct ntb_rx_info);
qp->rx_info = qp->tx_mw + tx_size;
qp->tx_mw = qp->rx_info + 1;
/* Due to housekeeping, there must be atleast 2 buffs */
qp->tx_max_frame = min(transport_mtu, tx_size / 2);
qp->tx_max_entry = tx_size / qp->tx_max_frame;
@ -851,6 +889,8 @@ static void ntb_transport_init_queue(struct ntb_transport *nt,
INIT_LIST_HEAD(&qp->rx_pend_q);
INIT_LIST_HEAD(&qp->rx_free_q);
INIT_LIST_HEAD(&qp->tx_free_q);
return 0;
}
int ntb_transport_init(struct pci_dev *pdev)
@ -889,8 +929,11 @@ int ntb_transport_init(struct pci_dev *pdev)
nt->qp_bitmap = ((u64) 1 << nt->max_qps) - 1;
for (i = 0; i < nt->max_qps; i++)
ntb_transport_init_queue(nt, i);
for (i = 0; i < nt->max_qps; i++) {
rc = ntb_transport_init_queue(nt, i);
if (rc)
goto err3;
}
INIT_DELAYED_WORK(&nt->link_work, ntb_transport_link_work);
INIT_WORK(&nt->link_cleanup, ntb_transport_link_cleanup);
@ -956,13 +999,19 @@ void ntb_transport_free(void *transport)
kfree(nt);
}
static void ntb_rx_copy_task(struct ntb_transport_qp *qp,
struct ntb_queue_entry *entry, void *offset)
static void ntb_rx_copy_callback(void *data)
{
struct ntb_queue_entry *entry = data;
struct ntb_transport_qp *qp = entry->qp;
void *cb_data = entry->cb_data;
unsigned int len = entry->len;
struct ntb_payload_header *hdr = entry->rx_hdr;
memcpy(entry->buf, offset, entry->len);
/* Ensure that the data is fully copied out before clearing the flag */
wmb();
hdr->flags = 0;
iowrite32(entry->index, &qp->rx_info->entry);
ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry, &qp->rx_free_q);
@ -970,6 +1019,86 @@ static void ntb_rx_copy_task(struct ntb_transport_qp *qp,
qp->rx_handler(qp, qp->cb_data, cb_data, len);
}
static void ntb_memcpy_rx(struct ntb_queue_entry *entry, void *offset)
{
void *buf = entry->buf;
size_t len = entry->len;
memcpy(buf, offset, len);
ntb_rx_copy_callback(entry);
}
static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset,
size_t len)
{
struct dma_async_tx_descriptor *txd;
struct ntb_transport_qp *qp = entry->qp;
struct dma_chan *chan = qp->dma_chan;
struct dma_device *device;
size_t pay_off, buff_off;
dma_addr_t src, dest;
dma_cookie_t cookie;
void *buf = entry->buf;
unsigned long flags;
entry->len = len;
if (!chan)
goto err;
if (len < copy_bytes)
goto err1;
device = chan->device;
pay_off = (size_t) offset & ~PAGE_MASK;
buff_off = (size_t) buf & ~PAGE_MASK;
if (!is_dma_copy_aligned(device, pay_off, buff_off, len))
goto err1;
dest = dma_map_single(device->dev, buf, len, DMA_FROM_DEVICE);
if (dma_mapping_error(device->dev, dest))
goto err1;
src = dma_map_single(device->dev, offset, len, DMA_TO_DEVICE);
if (dma_mapping_error(device->dev, src))
goto err2;
flags = DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SRC_UNMAP_SINGLE |
DMA_PREP_INTERRUPT;
txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags);
if (!txd)
goto err3;
txd->callback = ntb_rx_copy_callback;
txd->callback_param = entry;
cookie = dmaengine_submit(txd);
if (dma_submit_error(cookie))
goto err3;
qp->last_cookie = cookie;
qp->rx_async++;
return;
err3:
dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE);
err2:
dma_unmap_single(device->dev, dest, len, DMA_FROM_DEVICE);
err1:
/* If the callbacks come out of order, the writing of the index to the
* last completed will be out of order. This may result in the
* receive stalling forever.
*/
dma_sync_wait(chan, qp->last_cookie);
err:
ntb_memcpy_rx(entry, offset);
qp->rx_memcpy++;
}
static int ntb_process_rxc(struct ntb_transport_qp *qp)
{
struct ntb_payload_header *hdr;
@ -1008,41 +1137,45 @@ static int ntb_process_rxc(struct ntb_transport_qp *qp)
if (hdr->flags & LINK_DOWN_FLAG) {
ntb_qp_link_down(qp);
ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
&qp->rx_pend_q);
goto out;
goto err;
}
dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
"rx offset %u, ver %u - %d payload received, buf size %d\n",
qp->rx_index, hdr->ver, hdr->len, entry->len);
if (hdr->len <= entry->len) {
entry->len = hdr->len;
ntb_rx_copy_task(qp, entry, offset);
} else {
ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
&qp->rx_pend_q);
qp->rx_bytes += hdr->len;
qp->rx_pkts++;
if (hdr->len > entry->len) {
qp->rx_err_oflow++;
dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
"RX overflow! Wanted %d got %d\n",
hdr->len, entry->len);
goto err;
}
qp->rx_bytes += hdr->len;
qp->rx_pkts++;
entry->index = qp->rx_index;
entry->rx_hdr = hdr;
ntb_async_rx(entry, offset, hdr->len);
out:
qp->rx_index++;
qp->rx_index %= qp->rx_max_entry;
return 0;
err:
ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
&qp->rx_pend_q);
/* Ensure that the data is fully copied out before clearing the flag */
wmb();
hdr->flags = 0;
iowrite32(qp->rx_index, &qp->rx_info->entry);
qp->rx_index++;
qp->rx_index %= qp->rx_max_entry;
return 0;
goto out;
}
static void ntb_transport_rx(unsigned long data)
@ -1058,6 +1191,9 @@ static void ntb_transport_rx(unsigned long data)
if (rc)
break;
}
if (qp->dma_chan)
dma_async_issue_pending(qp->dma_chan);
}
static void ntb_transport_rxc_db(void *data, int db_num)
@ -1070,19 +1206,13 @@ static void ntb_transport_rxc_db(void *data, int db_num)
tasklet_schedule(&qp->rx_work);
}
static void ntb_tx_copy_task(struct ntb_transport_qp *qp,
struct ntb_queue_entry *entry,
void __iomem *offset)
static void ntb_tx_copy_callback(void *data)
{
struct ntb_payload_header __iomem *hdr;
struct ntb_queue_entry *entry = data;
struct ntb_transport_qp *qp = entry->qp;
struct ntb_payload_header __iomem *hdr = entry->tx_hdr;
memcpy_toio(offset, entry->buf, entry->len);
hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
iowrite32(entry->len, &hdr->len);
iowrite32((u32) qp->tx_pkts, &hdr->ver);
/* Ensure that the data is fully copied out before setting the flag */
/* Ensure that the data is fully copied out before setting the flags */
wmb();
iowrite32(entry->flags | DESC_DONE_FLAG, &hdr->flags);
@ -1103,15 +1233,81 @@ static void ntb_tx_copy_task(struct ntb_transport_qp *qp,
ntb_list_add(&qp->ntb_tx_free_q_lock, &entry->entry, &qp->tx_free_q);
}
static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset)
{
memcpy_toio(offset, entry->buf, entry->len);
ntb_tx_copy_callback(entry);
}
static void ntb_async_tx(struct ntb_transport_qp *qp,
struct ntb_queue_entry *entry)
{
struct ntb_payload_header __iomem *hdr;
struct dma_async_tx_descriptor *txd;
struct dma_chan *chan = qp->dma_chan;
struct dma_device *device;
size_t dest_off, buff_off;
dma_addr_t src, dest;
dma_cookie_t cookie;
void __iomem *offset;
size_t len = entry->len;
void *buf = entry->buf;
unsigned long flags;
offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
entry->tx_hdr = hdr;
iowrite32(entry->len, &hdr->len);
iowrite32((u32) qp->tx_pkts, &hdr->ver);
if (!chan)
goto err;
if (len < copy_bytes)
goto err;
device = chan->device;
dest = qp->tx_mw_phys + qp->tx_max_frame * qp->tx_index;
buff_off = (size_t) buf & ~PAGE_MASK;
dest_off = (size_t) dest & ~PAGE_MASK;
if (!is_dma_copy_aligned(device, buff_off, dest_off, len))
goto err;
src = dma_map_single(device->dev, buf, len, DMA_TO_DEVICE);
if (dma_mapping_error(device->dev, src))
goto err;
flags = DMA_COMPL_SRC_UNMAP_SINGLE | DMA_PREP_INTERRUPT;
txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags);
if (!txd)
goto err1;
txd->callback = ntb_tx_copy_callback;
txd->callback_param = entry;
cookie = dmaengine_submit(txd);
if (dma_submit_error(cookie))
goto err1;
dma_async_issue_pending(chan);
qp->tx_async++;
return;
err1:
dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE);
err:
ntb_memcpy_tx(entry, offset);
qp->tx_memcpy++;
}
static int ntb_process_tx(struct ntb_transport_qp *qp,
struct ntb_queue_entry *entry)
{
void __iomem *offset;
offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%lld - offset %p, tx %u, entry len %d flags %x buff %p\n",
qp->tx_pkts, offset, qp->tx_index, entry->len, entry->flags,
dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%lld - tx %u, entry len %d flags %x buff %p\n",
qp->tx_pkts, qp->tx_index, entry->len, entry->flags,
entry->buf);
if (qp->tx_index == qp->remote_rx_info->entry) {
qp->tx_ring_full++;
@ -1127,7 +1323,7 @@ static int ntb_process_tx(struct ntb_transport_qp *qp,
return 0;
}
ntb_tx_copy_task(qp, entry, offset);
ntb_async_tx(qp, entry);
qp->tx_index++;
qp->tx_index %= qp->tx_max_entry;
@ -1213,11 +1409,18 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev,
qp->tx_handler = handlers->tx_handler;
qp->event_handler = handlers->event_handler;
qp->dma_chan = dma_find_channel(DMA_MEMCPY);
if (!qp->dma_chan)
dev_info(&pdev->dev, "Unable to allocate DMA channel, using CPU instead\n");
else
dmaengine_get();
for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
entry = kzalloc(sizeof(struct ntb_queue_entry), GFP_ATOMIC);
if (!entry)
goto err1;
entry->qp = qp;
ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry,
&qp->rx_free_q);
}
@ -1227,6 +1430,7 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev,
if (!entry)
goto err2;
entry->qp = qp;
ntb_list_add(&qp->ntb_tx_free_q_lock, &entry->entry,
&qp->tx_free_q);
}
@ -1272,11 +1476,26 @@ void ntb_transport_free_queue(struct ntb_transport_qp *qp)
pdev = ntb_query_pdev(qp->ndev);
cancel_delayed_work_sync(&qp->link_work);
if (qp->dma_chan) {
struct dma_chan *chan = qp->dma_chan;
/* Putting the dma_chan to NULL will force any new traffic to be
* processed by the CPU instead of the DAM engine
*/
qp->dma_chan = NULL;
/* Try to be nice and wait for any queued DMA engine
* transactions to process before smashing it with a rock
*/
dma_sync_wait(chan, qp->last_cookie);
dmaengine_terminate_all(chan);
dmaengine_put();
}
ntb_unregister_db_callback(qp->ndev, qp->qp_num);
tasklet_disable(&qp->rx_work);
cancel_delayed_work_sync(&qp->link_work);
while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q)))
kfree(entry);
@ -1382,8 +1601,10 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
return -EINVAL;
entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
if (!entry)
if (!entry) {
qp->tx_err_no_buf++;
return -ENOMEM;
}
entry->cb_data = cb;
entry->buf = data;
@ -1499,9 +1720,18 @@ EXPORT_SYMBOL_GPL(ntb_transport_qp_num);
*/
unsigned int ntb_transport_max_size(struct ntb_transport_qp *qp)
{
unsigned int max;
if (!qp)
return 0;
return qp->tx_max_frame - sizeof(struct ntb_payload_header);
if (!qp->dma_chan)
return qp->tx_max_frame - sizeof(struct ntb_payload_header);
/* If DMA engine usage is possible, try to find the max size for that */
max = qp->tx_max_frame - sizeof(struct ntb_payload_header);
max -= max % (1 << qp->dma_chan->device->copy_align);
return max;
}
EXPORT_SYMBOL_GPL(ntb_transport_max_size);