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linux/drivers/net/cxgb3/sge.c
Divy Le Ray e0994eb1d9 cxgb3 - Feed Rx free list with pages 
Populate Rx free list with pages.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
2007-02-27 04:27:12 -05:00

2890 lines
81 KiB
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/*
* Copyright (c) 2005-2007 Chelsio, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/dma-mapping.h>
#include "common.h"
#include "regs.h"
#include "sge_defs.h"
#include "t3_cpl.h"
#include "firmware_exports.h"
#define USE_GTS 0
#define SGE_RX_SM_BUF_SIZE 1536
/*
* If USE_RX_PAGE is defined, the small freelist populated with (partial)
* pages instead of skbs. Pages are carved up into RX_PAGE_SIZE chunks (must
* be a multiple of the host page size).
*/
#define USE_RX_PAGE
#define RX_PAGE_SIZE 2048
/*
* skb freelist packets are copied into a new skb (and the freelist one is
* reused) if their len is <=
*/
#define SGE_RX_COPY_THRES 256
/*
* Minimum number of freelist entries before we start dropping TUNNEL frames.
*/
#define SGE_RX_DROP_THRES 16
/*
* Period of the Tx buffer reclaim timer. This timer does not need to run
* frequently as Tx buffers are usually reclaimed by new Tx packets.
*/
#define TX_RECLAIM_PERIOD (HZ / 4)
/* WR size in bytes */
#define WR_LEN (WR_FLITS * 8)
/*
* Types of Tx queues in each queue set. Order here matters, do not change.
*/
enum { TXQ_ETH, TXQ_OFLD, TXQ_CTRL };
/* Values for sge_txq.flags */
enum {
TXQ_RUNNING = 1 << 0, /* fetch engine is running */
TXQ_LAST_PKT_DB = 1 << 1, /* last packet rang the doorbell */
};
struct tx_desc {
u64 flit[TX_DESC_FLITS];
};
struct rx_desc {
__be32 addr_lo;
__be32 len_gen;
__be32 gen2;
__be32 addr_hi;
};
struct tx_sw_desc { /* SW state per Tx descriptor */
struct sk_buff *skb;
};
struct rx_sw_desc { /* SW state per Rx descriptor */
union {
struct sk_buff *skb;
struct sge_fl_page page;
} t;
DECLARE_PCI_UNMAP_ADDR(dma_addr);
};
struct rsp_desc { /* response queue descriptor */
struct rss_header rss_hdr;
__be32 flags;
__be32 len_cq;
u8 imm_data[47];
u8 intr_gen;
};
struct unmap_info { /* packet unmapping info, overlays skb->cb */
int sflit; /* start flit of first SGL entry in Tx descriptor */
u16 fragidx; /* first page fragment in current Tx descriptor */
u16 addr_idx; /* buffer index of first SGL entry in descriptor */
u32 len; /* mapped length of skb main body */
};
/*
* Holds unmapping information for Tx packets that need deferred unmapping.
* This structure lives at skb->head and must be allocated by callers.
*/
struct deferred_unmap_info {
struct pci_dev *pdev;
dma_addr_t addr[MAX_SKB_FRAGS + 1];
};
/*
* Maps a number of flits to the number of Tx descriptors that can hold them.
* The formula is
*
* desc = 1 + (flits - 2) / (WR_FLITS - 1).
*
* HW allows up to 4 descriptors to be combined into a WR.
*/
static u8 flit_desc_map[] = {
0,
#if SGE_NUM_GENBITS == 1
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
#elif SGE_NUM_GENBITS == 2
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
#else
# error "SGE_NUM_GENBITS must be 1 or 2"
#endif
};
static inline struct sge_qset *fl_to_qset(const struct sge_fl *q, int qidx)
{
return container_of(q, struct sge_qset, fl[qidx]);
}
static inline struct sge_qset *rspq_to_qset(const struct sge_rspq *q)
{
return container_of(q, struct sge_qset, rspq);
}
static inline struct sge_qset *txq_to_qset(const struct sge_txq *q, int qidx)
{
return container_of(q, struct sge_qset, txq[qidx]);
}
/**
* refill_rspq - replenish an SGE response queue
* @adapter: the adapter
* @q: the response queue to replenish
* @credits: how many new responses to make available
*
* Replenishes a response queue by making the supplied number of responses
* available to HW.
*/
static inline void refill_rspq(struct adapter *adapter,
const struct sge_rspq *q, unsigned int credits)
{
t3_write_reg(adapter, A_SG_RSPQ_CREDIT_RETURN,
V_RSPQ(q->cntxt_id) | V_CREDITS(credits));
}
/**
* need_skb_unmap - does the platform need unmapping of sk_buffs?
*
* Returns true if the platfrom needs sk_buff unmapping. The compiler
* optimizes away unecessary code if this returns true.
*/
static inline int need_skb_unmap(void)
{
/*
* This structure is used to tell if the platfrom needs buffer
* unmapping by checking if DECLARE_PCI_UNMAP_ADDR defines anything.
*/
struct dummy {
DECLARE_PCI_UNMAP_ADDR(addr);
};
return sizeof(struct dummy) != 0;
}
/**
* unmap_skb - unmap a packet main body and its page fragments
* @skb: the packet
* @q: the Tx queue containing Tx descriptors for the packet
* @cidx: index of Tx descriptor
* @pdev: the PCI device
*
* Unmap the main body of an sk_buff and its page fragments, if any.
* Because of the fairly complicated structure of our SGLs and the desire
* to conserve space for metadata, we keep the information necessary to
* unmap an sk_buff partly in the sk_buff itself (in its cb), and partly
* in the Tx descriptors (the physical addresses of the various data
* buffers). The send functions initialize the state in skb->cb so we
* can unmap the buffers held in the first Tx descriptor here, and we
* have enough information at this point to update the state for the next
* Tx descriptor.
*/
static inline void unmap_skb(struct sk_buff *skb, struct sge_txq *q,
unsigned int cidx, struct pci_dev *pdev)
{
const struct sg_ent *sgp;
struct unmap_info *ui = (struct unmap_info *)skb->cb;
int nfrags, frag_idx, curflit, j = ui->addr_idx;
sgp = (struct sg_ent *)&q->desc[cidx].flit[ui->sflit];
if (ui->len) {
pci_unmap_single(pdev, be64_to_cpu(sgp->addr[0]), ui->len,
PCI_DMA_TODEVICE);
ui->len = 0; /* so we know for next descriptor for this skb */
j = 1;
}
frag_idx = ui->fragidx;
curflit = ui->sflit + 1 + j;
nfrags = skb_shinfo(skb)->nr_frags;
while (frag_idx < nfrags && curflit < WR_FLITS) {
pci_unmap_page(pdev, be64_to_cpu(sgp->addr[j]),
skb_shinfo(skb)->frags[frag_idx].size,
PCI_DMA_TODEVICE);
j ^= 1;
if (j == 0) {
sgp++;
curflit++;
}
curflit++;
frag_idx++;
}
if (frag_idx < nfrags) { /* SGL continues into next Tx descriptor */
ui->fragidx = frag_idx;
ui->addr_idx = j;
ui->sflit = curflit - WR_FLITS - j; /* sflit can be -1 */
}
}
/**
* free_tx_desc - reclaims Tx descriptors and their buffers
* @adapter: the adapter
* @q: the Tx queue to reclaim descriptors from
* @n: the number of descriptors to reclaim
*
* Reclaims Tx descriptors from an SGE Tx queue and frees the associated
* Tx buffers. Called with the Tx queue lock held.
*/
static void free_tx_desc(struct adapter *adapter, struct sge_txq *q,
unsigned int n)
{
struct tx_sw_desc *d;
struct pci_dev *pdev = adapter->pdev;
unsigned int cidx = q->cidx;
const int need_unmap = need_skb_unmap() &&
q->cntxt_id >= FW_TUNNEL_SGEEC_START;
d = &q->sdesc[cidx];
while (n--) {
if (d->skb) { /* an SGL is present */
if (need_unmap)
unmap_skb(d->skb, q, cidx, pdev);
if (d->skb->priority == cidx)
kfree_skb(d->skb);
}
++d;
if (++cidx == q->size) {
cidx = 0;
d = q->sdesc;
}
}
q->cidx = cidx;
}
/**
* reclaim_completed_tx - reclaims completed Tx descriptors
* @adapter: the adapter
* @q: the Tx queue to reclaim completed descriptors from
*
* Reclaims Tx descriptors that the SGE has indicated it has processed,
* and frees the associated buffers if possible. Called with the Tx
* queue's lock held.
*/
static inline void reclaim_completed_tx(struct adapter *adapter,
struct sge_txq *q)
{
unsigned int reclaim = q->processed - q->cleaned;
if (reclaim) {
free_tx_desc(adapter, q, reclaim);
q->cleaned += reclaim;
q->in_use -= reclaim;
}
}
/**
* should_restart_tx - are there enough resources to restart a Tx queue?
* @q: the Tx queue
*
* Checks if there are enough descriptors to restart a suspended Tx queue.
*/
static inline int should_restart_tx(const struct sge_txq *q)
{
unsigned int r = q->processed - q->cleaned;
return q->in_use - r < (q->size >> 1);
}
/**
* free_rx_bufs - free the Rx buffers on an SGE free list
* @pdev: the PCI device associated with the adapter
* @rxq: the SGE free list to clean up
*
* Release the buffers on an SGE free-buffer Rx queue. HW fetching from
* this queue should be stopped before calling this function.
*/
static void free_rx_bufs(struct pci_dev *pdev, struct sge_fl *q)
{
unsigned int cidx = q->cidx;
while (q->credits--) {
struct rx_sw_desc *d = &q->sdesc[cidx];
pci_unmap_single(pdev, pci_unmap_addr(d, dma_addr),
q->buf_size, PCI_DMA_FROMDEVICE);
if (q->buf_size != RX_PAGE_SIZE) {
kfree_skb(d->t.skb);
d->t.skb = NULL;
} else {
if (d->t.page.frag.page)
put_page(d->t.page.frag.page);
d->t.page.frag.page = NULL;
}
if (++cidx == q->size)
cidx = 0;
}
if (q->page.frag.page)
put_page(q->page.frag.page);
q->page.frag.page = NULL;
}
/**
* add_one_rx_buf - add a packet buffer to a free-buffer list
* @va: va of the buffer to add
* @len: the buffer length
* @d: the HW Rx descriptor to write
* @sd: the SW Rx descriptor to write
* @gen: the generation bit value
* @pdev: the PCI device associated with the adapter
*
* Add a buffer of the given length to the supplied HW and SW Rx
* descriptors.
*/
static inline void add_one_rx_buf(unsigned char *va, unsigned int len,
struct rx_desc *d, struct rx_sw_desc *sd,
unsigned int gen, struct pci_dev *pdev)
{
dma_addr_t mapping;
mapping = pci_map_single(pdev, va, len, PCI_DMA_FROMDEVICE);
pci_unmap_addr_set(sd, dma_addr, mapping);
d->addr_lo = cpu_to_be32(mapping);
d->addr_hi = cpu_to_be32((u64) mapping >> 32);
wmb();
d->len_gen = cpu_to_be32(V_FLD_GEN1(gen));
d->gen2 = cpu_to_be32(V_FLD_GEN2(gen));
}
/**
* refill_fl - refill an SGE free-buffer list
* @adapter: the adapter
* @q: the free-list to refill
* @n: the number of new buffers to allocate
* @gfp: the gfp flags for allocating new buffers
*
* (Re)populate an SGE free-buffer list with up to @n new packet buffers,
* allocated with the supplied gfp flags. The caller must assure that
* @n does not exceed the queue's capacity.
*/
static void refill_fl(struct adapter *adap, struct sge_fl *q, int n, gfp_t gfp)
{
struct rx_sw_desc *sd = &q->sdesc[q->pidx];
struct rx_desc *d = &q->desc[q->pidx];
struct sge_fl_page *p = &q->page;
while (n--) {
unsigned char *va;
if (unlikely(q->buf_size != RX_PAGE_SIZE)) {
struct sk_buff *skb = alloc_skb(q->buf_size, gfp);
if (!skb) {
q->alloc_failed++;
break;
}
va = skb->data;
sd->t.skb = skb;
} else {
if (!p->frag.page) {
p->frag.page = alloc_pages(gfp, 0);
if (unlikely(!p->frag.page)) {
q->alloc_failed++;
break;
} else {
p->frag.size = RX_PAGE_SIZE;
p->frag.page_offset = 0;
p->va = page_address(p->frag.page);
}
}
memcpy(&sd->t, p, sizeof(*p));
va = p->va;
p->frag.page_offset += RX_PAGE_SIZE;
BUG_ON(p->frag.page_offset > PAGE_SIZE);
p->va += RX_PAGE_SIZE;
if (p->frag.page_offset == PAGE_SIZE)
p->frag.page = NULL;
else
get_page(p->frag.page);
}
add_one_rx_buf(va, q->buf_size, d, sd, q->gen, adap->pdev);
d++;
sd++;
if (++q->pidx == q->size) {
q->pidx = 0;
q->gen ^= 1;
sd = q->sdesc;
d = q->desc;
}
q->credits++;
}
t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
}
static inline void __refill_fl(struct adapter *adap, struct sge_fl *fl)
{
refill_fl(adap, fl, min(16U, fl->size - fl->credits), GFP_ATOMIC);
}
/**
* recycle_rx_buf - recycle a receive buffer
* @adapter: the adapter
* @q: the SGE free list
* @idx: index of buffer to recycle
*
* Recycles the specified buffer on the given free list by adding it at
* the next available slot on the list.
*/
static void recycle_rx_buf(struct adapter *adap, struct sge_fl *q,
unsigned int idx)
{
struct rx_desc *from = &q->desc[idx];
struct rx_desc *to = &q->desc[q->pidx];
memcpy(&q->sdesc[q->pidx], &q->sdesc[idx], sizeof(struct rx_sw_desc));
to->addr_lo = from->addr_lo; /* already big endian */
to->addr_hi = from->addr_hi; /* likewise */
wmb();
to->len_gen = cpu_to_be32(V_FLD_GEN1(q->gen));
to->gen2 = cpu_to_be32(V_FLD_GEN2(q->gen));
q->credits++;
if (++q->pidx == q->size) {
q->pidx = 0;
q->gen ^= 1;
}
t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
}
/**
* alloc_ring - allocate resources for an SGE descriptor ring
* @pdev: the PCI device
* @nelem: the number of descriptors
* @elem_size: the size of each descriptor
* @sw_size: the size of the SW state associated with each ring element
* @phys: the physical address of the allocated ring
* @metadata: address of the array holding the SW state for the ring
*
* Allocates resources for an SGE descriptor ring, such as Tx queues,
* free buffer lists, or response queues. Each SGE ring requires
* space for its HW descriptors plus, optionally, space for the SW state
* associated with each HW entry (the metadata). The function returns
* three values: the virtual address for the HW ring (the return value
* of the function), the physical address of the HW ring, and the address
* of the SW ring.
*/
static void *alloc_ring(struct pci_dev *pdev, size_t nelem, size_t elem_size,
size_t sw_size, dma_addr_t * phys, void *metadata)
{
size_t len = nelem * elem_size;
void *s = NULL;
void *p = dma_alloc_coherent(&pdev->dev, len, phys, GFP_KERNEL);
if (!p)
return NULL;
if (sw_size) {
s = kcalloc(nelem, sw_size, GFP_KERNEL);
if (!s) {
dma_free_coherent(&pdev->dev, len, p, *phys);
return NULL;
}
}
if (metadata)
*(void **)metadata = s;
memset(p, 0, len);
return p;
}
/**
* free_qset - free the resources of an SGE queue set
* @adapter: the adapter owning the queue set
* @q: the queue set
*
* Release the HW and SW resources associated with an SGE queue set, such
* as HW contexts, packet buffers, and descriptor rings. Traffic to the
* queue set must be quiesced prior to calling this.
*/
void t3_free_qset(struct adapter *adapter, struct sge_qset *q)
{
int i;
struct pci_dev *pdev = adapter->pdev;
if (q->tx_reclaim_timer.function)
del_timer_sync(&q->tx_reclaim_timer);
for (i = 0; i < SGE_RXQ_PER_SET; ++i)
if (q->fl[i].desc) {
spin_lock(&adapter->sge.reg_lock);
t3_sge_disable_fl(adapter, q->fl[i].cntxt_id);
spin_unlock(&adapter->sge.reg_lock);
free_rx_bufs(pdev, &q->fl[i]);
kfree(q->fl[i].sdesc);
dma_free_coherent(&pdev->dev,
q->fl[i].size *
sizeof(struct rx_desc), q->fl[i].desc,
q->fl[i].phys_addr);
}
for (i = 0; i < SGE_TXQ_PER_SET; ++i)
if (q->txq[i].desc) {
spin_lock(&adapter->sge.reg_lock);
t3_sge_enable_ecntxt(adapter, q->txq[i].cntxt_id, 0);
spin_unlock(&adapter->sge.reg_lock);
if (q->txq[i].sdesc) {
free_tx_desc(adapter, &q->txq[i],
q->txq[i].in_use);
kfree(q->txq[i].sdesc);
}
dma_free_coherent(&pdev->dev,
q->txq[i].size *
sizeof(struct tx_desc),
q->txq[i].desc, q->txq[i].phys_addr);
__skb_queue_purge(&q->txq[i].sendq);
}
if (q->rspq.desc) {
spin_lock(&adapter->sge.reg_lock);
t3_sge_disable_rspcntxt(adapter, q->rspq.cntxt_id);
spin_unlock(&adapter->sge.reg_lock);
dma_free_coherent(&pdev->dev,
q->rspq.size * sizeof(struct rsp_desc),
q->rspq.desc, q->rspq.phys_addr);
}
if (q->netdev)
q->netdev->atalk_ptr = NULL;
memset(q, 0, sizeof(*q));
}
/**
* init_qset_cntxt - initialize an SGE queue set context info
* @qs: the queue set
* @id: the queue set id
*
* Initializes the TIDs and context ids for the queues of a queue set.
*/
static void init_qset_cntxt(struct sge_qset *qs, unsigned int id)
{
qs->rspq.cntxt_id = id;
qs->fl[0].cntxt_id = 2 * id;
qs->fl[1].cntxt_id = 2 * id + 1;
qs->txq[TXQ_ETH].cntxt_id = FW_TUNNEL_SGEEC_START + id;
qs->txq[TXQ_ETH].token = FW_TUNNEL_TID_START + id;
qs->txq[TXQ_OFLD].cntxt_id = FW_OFLD_SGEEC_START + id;
qs->txq[TXQ_CTRL].cntxt_id = FW_CTRL_SGEEC_START + id;
qs->txq[TXQ_CTRL].token = FW_CTRL_TID_START + id;
}
/**
* sgl_len - calculates the size of an SGL of the given capacity
* @n: the number of SGL entries
*
* Calculates the number of flits needed for a scatter/gather list that
* can hold the given number of entries.
*/
static inline unsigned int sgl_len(unsigned int n)
{
/* alternatively: 3 * (n / 2) + 2 * (n & 1) */
return (3 * n) / 2 + (n & 1);
}
/**
* flits_to_desc - returns the num of Tx descriptors for the given flits
* @n: the number of flits
*
* Calculates the number of Tx descriptors needed for the supplied number
* of flits.
*/
static inline unsigned int flits_to_desc(unsigned int n)
{
BUG_ON(n >= ARRAY_SIZE(flit_desc_map));
return flit_desc_map[n];
}
/**
* get_imm_packet - return the next ingress packet buffer from a response
* @resp: the response descriptor containing the packet data
*
* Return a packet containing the immediate data of the given response.
*/
static inline struct sk_buff *get_imm_packet(const struct rsp_desc *resp)
{
struct sk_buff *skb = alloc_skb(IMMED_PKT_SIZE, GFP_ATOMIC);
if (skb) {
__skb_put(skb, IMMED_PKT_SIZE);
memcpy(skb->data, resp->imm_data, IMMED_PKT_SIZE);
}
return skb;
}
/**
* calc_tx_descs - calculate the number of Tx descriptors for a packet
* @skb: the packet
*
* Returns the number of Tx descriptors needed for the given Ethernet
* packet. Ethernet packets require addition of WR and CPL headers.
*/
static inline unsigned int calc_tx_descs(const struct sk_buff *skb)
{
unsigned int flits;
if (skb->len <= WR_LEN - sizeof(struct cpl_tx_pkt))
return 1;
flits = sgl_len(skb_shinfo(skb)->nr_frags + 1) + 2;
if (skb_shinfo(skb)->gso_size)
flits++;
return flits_to_desc(flits);
}
/**
* make_sgl - populate a scatter/gather list for a packet
* @skb: the packet
* @sgp: the SGL to populate
* @start: start address of skb main body data to include in the SGL
* @len: length of skb main body data to include in the SGL
* @pdev: the PCI device
*
* Generates a scatter/gather list for the buffers that make up a packet
* and returns the SGL size in 8-byte words. The caller must size the SGL
* appropriately.
*/
static inline unsigned int make_sgl(const struct sk_buff *skb,
struct sg_ent *sgp, unsigned char *start,
unsigned int len, struct pci_dev *pdev)
{
dma_addr_t mapping;
unsigned int i, j = 0, nfrags;
if (len) {
mapping = pci_map_single(pdev, start, len, PCI_DMA_TODEVICE);
sgp->len[0] = cpu_to_be32(len);
sgp->addr[0] = cpu_to_be64(mapping);
j = 1;
}
nfrags = skb_shinfo(skb)->nr_frags;
for (i = 0; i < nfrags; i++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
mapping = pci_map_page(pdev, frag->page, frag->page_offset,
frag->size, PCI_DMA_TODEVICE);
sgp->len[j] = cpu_to_be32(frag->size);
sgp->addr[j] = cpu_to_be64(mapping);
j ^= 1;
if (j == 0)
++sgp;
}
if (j)
sgp->len[j] = 0;
return ((nfrags + (len != 0)) * 3) / 2 + j;
}
/**
* check_ring_tx_db - check and potentially ring a Tx queue's doorbell
* @adap: the adapter
* @q: the Tx queue
*
* Ring the doorbel if a Tx queue is asleep. There is a natural race,
* where the HW is going to sleep just after we checked, however,
* then the interrupt handler will detect the outstanding TX packet
* and ring the doorbell for us.
*
* When GTS is disabled we unconditionally ring the doorbell.
*/
static inline void check_ring_tx_db(struct adapter *adap, struct sge_txq *q)
{
#if USE_GTS
clear_bit(TXQ_LAST_PKT_DB, &q->flags);
if (test_and_set_bit(TXQ_RUNNING, &q->flags) == 0) {
set_bit(TXQ_LAST_PKT_DB, &q->flags);
t3_write_reg(adap, A_SG_KDOORBELL,
F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
}
#else
wmb(); /* write descriptors before telling HW */
t3_write_reg(adap, A_SG_KDOORBELL,
F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
#endif
}
static inline void wr_gen2(struct tx_desc *d, unsigned int gen)
{
#if SGE_NUM_GENBITS == 2
d->flit[TX_DESC_FLITS - 1] = cpu_to_be64(gen);
#endif
}
/**
* write_wr_hdr_sgl - write a WR header and, optionally, SGL
* @ndesc: number of Tx descriptors spanned by the SGL
* @skb: the packet corresponding to the WR
* @d: first Tx descriptor to be written
* @pidx: index of above descriptors
* @q: the SGE Tx queue
* @sgl: the SGL
* @flits: number of flits to the start of the SGL in the first descriptor
* @sgl_flits: the SGL size in flits
* @gen: the Tx descriptor generation
* @wr_hi: top 32 bits of WR header based on WR type (big endian)
* @wr_lo: low 32 bits of WR header based on WR type (big endian)
*
* Write a work request header and an associated SGL. If the SGL is
* small enough to fit into one Tx descriptor it has already been written
* and we just need to write the WR header. Otherwise we distribute the
* SGL across the number of descriptors it spans.
*/
static void write_wr_hdr_sgl(unsigned int ndesc, struct sk_buff *skb,
struct tx_desc *d, unsigned int pidx,
const struct sge_txq *q,
const struct sg_ent *sgl,
unsigned int flits, unsigned int sgl_flits,
unsigned int gen, unsigned int wr_hi,
unsigned int wr_lo)
{
struct work_request_hdr *wrp = (struct work_request_hdr *)d;
struct tx_sw_desc *sd = &q->sdesc[pidx];
sd->skb = skb;
if (need_skb_unmap()) {
struct unmap_info *ui = (struct unmap_info *)skb->cb;
ui->fragidx = 0;
ui->addr_idx = 0;
ui->sflit = flits;
}
if (likely(ndesc == 1)) {
skb->priority = pidx;
wrp->wr_hi = htonl(F_WR_SOP | F_WR_EOP | V_WR_DATATYPE(1) |
V_WR_SGLSFLT(flits)) | wr_hi;
wmb();
wrp->wr_lo = htonl(V_WR_LEN(flits + sgl_flits) |
V_WR_GEN(gen)) | wr_lo;
wr_gen2(d, gen);
} else {
unsigned int ogen = gen;
const u64 *fp = (const u64 *)sgl;
struct work_request_hdr *wp = wrp;
wrp->wr_hi = htonl(F_WR_SOP | V_WR_DATATYPE(1) |
V_WR_SGLSFLT(flits)) | wr_hi;
while (sgl_flits) {
unsigned int avail = WR_FLITS - flits;
if (avail > sgl_flits)
avail = sgl_flits;
memcpy(&d->flit[flits], fp, avail * sizeof(*fp));
sgl_flits -= avail;
ndesc--;
if (!sgl_flits)
break;
fp += avail;
d++;
sd++;
if (++pidx == q->size) {
pidx = 0;
gen ^= 1;
d = q->desc;
sd = q->sdesc;
}
sd->skb = skb;
wrp = (struct work_request_hdr *)d;
wrp->wr_hi = htonl(V_WR_DATATYPE(1) |
V_WR_SGLSFLT(1)) | wr_hi;
wrp->wr_lo = htonl(V_WR_LEN(min(WR_FLITS,
sgl_flits + 1)) |
V_WR_GEN(gen)) | wr_lo;
wr_gen2(d, gen);
flits = 1;
}
skb->priority = pidx;
wrp->wr_hi |= htonl(F_WR_EOP);
wmb();
wp->wr_lo = htonl(V_WR_LEN(WR_FLITS) | V_WR_GEN(ogen)) | wr_lo;
wr_gen2((struct tx_desc *)wp, ogen);
WARN_ON(ndesc != 0);
}
}
/**
* write_tx_pkt_wr - write a TX_PKT work request
* @adap: the adapter
* @skb: the packet to send
* @pi: the egress interface
* @pidx: index of the first Tx descriptor to write
* @gen: the generation value to use
* @q: the Tx queue
* @ndesc: number of descriptors the packet will occupy
* @compl: the value of the COMPL bit to use
*
* Generate a TX_PKT work request to send the supplied packet.
*/
static void write_tx_pkt_wr(struct adapter *adap, struct sk_buff *skb,
const struct port_info *pi,
unsigned int pidx, unsigned int gen,
struct sge_txq *q, unsigned int ndesc,
unsigned int compl)
{
unsigned int flits, sgl_flits, cntrl, tso_info;
struct sg_ent *sgp, sgl[MAX_SKB_FRAGS / 2 + 1];
struct tx_desc *d = &q->desc[pidx];
struct cpl_tx_pkt *cpl = (struct cpl_tx_pkt *)d;
cpl->len = htonl(skb->len | 0x80000000);
cntrl = V_TXPKT_INTF(pi->port_id);
if (vlan_tx_tag_present(skb) && pi->vlan_grp)
cntrl |= F_TXPKT_VLAN_VLD | V_TXPKT_VLAN(vlan_tx_tag_get(skb));
tso_info = V_LSO_MSS(skb_shinfo(skb)->gso_size);
if (tso_info) {
int eth_type;
struct cpl_tx_pkt_lso *hdr = (struct cpl_tx_pkt_lso *)cpl;
d->flit[2] = 0;
cntrl |= V_TXPKT_OPCODE(CPL_TX_PKT_LSO);
hdr->cntrl = htonl(cntrl);
eth_type = skb->nh.raw - skb->data == ETH_HLEN ?
CPL_ETH_II : CPL_ETH_II_VLAN;
tso_info |= V_LSO_ETH_TYPE(eth_type) |
V_LSO_IPHDR_WORDS(skb->nh.iph->ihl) |
V_LSO_TCPHDR_WORDS(skb->h.th->doff);
hdr->lso_info = htonl(tso_info);
flits = 3;
} else {
cntrl |= V_TXPKT_OPCODE(CPL_TX_PKT);
cntrl |= F_TXPKT_IPCSUM_DIS; /* SW calculates IP csum */
cntrl |= V_TXPKT_L4CSUM_DIS(skb->ip_summed != CHECKSUM_PARTIAL);
cpl->cntrl = htonl(cntrl);
if (skb->len <= WR_LEN - sizeof(*cpl)) {
q->sdesc[pidx].skb = NULL;
if (!skb->data_len)
memcpy(&d->flit[2], skb->data, skb->len);
else
skb_copy_bits(skb, 0, &d->flit[2], skb->len);
flits = (skb->len + 7) / 8 + 2;
cpl->wr.wr_hi = htonl(V_WR_BCNTLFLT(skb->len & 7) |
V_WR_OP(FW_WROPCODE_TUNNEL_TX_PKT)
| F_WR_SOP | F_WR_EOP | compl);
wmb();
cpl->wr.wr_lo = htonl(V_WR_LEN(flits) | V_WR_GEN(gen) |
V_WR_TID(q->token));
wr_gen2(d, gen);
kfree_skb(skb);
return;
}
flits = 2;
}
sgp = ndesc == 1 ? (struct sg_ent *)&d->flit[flits] : sgl;
sgl_flits = make_sgl(skb, sgp, skb->data, skb_headlen(skb), adap->pdev);
if (need_skb_unmap())
((struct unmap_info *)skb->cb)->len = skb_headlen(skb);
write_wr_hdr_sgl(ndesc, skb, d, pidx, q, sgl, flits, sgl_flits, gen,
htonl(V_WR_OP(FW_WROPCODE_TUNNEL_TX_PKT) | compl),
htonl(V_WR_TID(q->token)));
}
/**
* eth_xmit - add a packet to the Ethernet Tx queue
* @skb: the packet
* @dev: the egress net device
*
* Add a packet to an SGE Tx queue. Runs with softirqs disabled.
*/
int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev)
{
unsigned int ndesc, pidx, credits, gen, compl;
const struct port_info *pi = netdev_priv(dev);
struct adapter *adap = dev->priv;
struct sge_qset *qs = dev2qset(dev);
struct sge_txq *q = &qs->txq[TXQ_ETH];
/*
* The chip min packet length is 9 octets but play safe and reject
* anything shorter than an Ethernet header.
*/
if (unlikely(skb->len < ETH_HLEN)) {
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
spin_lock(&q->lock);
reclaim_completed_tx(adap, q);
credits = q->size - q->in_use;
ndesc = calc_tx_descs(skb);
if (unlikely(credits < ndesc)) {
if (!netif_queue_stopped(dev)) {
netif_stop_queue(dev);
set_bit(TXQ_ETH, &qs->txq_stopped);
q->stops++;
dev_err(&adap->pdev->dev,
"%s: Tx ring %u full while queue awake!\n",
dev->name, q->cntxt_id & 7);
}
spin_unlock(&q->lock);
return NETDEV_TX_BUSY;
}
q->in_use += ndesc;
if (unlikely(credits - ndesc < q->stop_thres)) {
q->stops++;
netif_stop_queue(dev);
set_bit(TXQ_ETH, &qs->txq_stopped);
#if !USE_GTS
if (should_restart_tx(q) &&
test_and_clear_bit(TXQ_ETH, &qs->txq_stopped)) {
q->restarts++;
netif_wake_queue(dev);
}
#endif
}
gen = q->gen;
q->unacked += ndesc;
compl = (q->unacked & 8) << (S_WR_COMPL - 3);
q->unacked &= 7;
pidx = q->pidx;
q->pidx += ndesc;
if (q->pidx >= q->size) {
q->pidx -= q->size;
q->gen ^= 1;
}
/* update port statistics */
if (skb->ip_summed == CHECKSUM_COMPLETE)
qs->port_stats[SGE_PSTAT_TX_CSUM]++;
if (skb_shinfo(skb)->gso_size)
qs->port_stats[SGE_PSTAT_TSO]++;
if (vlan_tx_tag_present(skb) && pi->vlan_grp)
qs->port_stats[SGE_PSTAT_VLANINS]++;
dev->trans_start = jiffies;
spin_unlock(&q->lock);
/*
* We do not use Tx completion interrupts to free DMAd Tx packets.
* This is good for performamce but means that we rely on new Tx
* packets arriving to run the destructors of completed packets,
* which open up space in their sockets' send queues. Sometimes
* we do not get such new packets causing Tx to stall. A single
* UDP transmitter is a good example of this situation. We have
* a clean up timer that periodically reclaims completed packets
* but it doesn't run often enough (nor do we want it to) to prevent
* lengthy stalls. A solution to this problem is to run the
* destructor early, after the packet is queued but before it's DMAd.
* A cons is that we lie to socket memory accounting, but the amount
* of extra memory is reasonable (limited by the number of Tx
* descriptors), the packets do actually get freed quickly by new
* packets almost always, and for protocols like TCP that wait for
* acks to really free up the data the extra memory is even less.
* On the positive side we run the destructors on the sending CPU
* rather than on a potentially different completing CPU, usually a
* good thing. We also run them without holding our Tx queue lock,
* unlike what reclaim_completed_tx() would otherwise do.
*
* Run the destructor before telling the DMA engine about the packet
* to make sure it doesn't complete and get freed prematurely.
*/
if (likely(!skb_shared(skb)))
skb_orphan(skb);
write_tx_pkt_wr(adap, skb, pi, pidx, gen, q, ndesc, compl);
check_ring_tx_db(adap, q);
return NETDEV_TX_OK;
}
/**
* write_imm - write a packet into a Tx descriptor as immediate data
* @d: the Tx descriptor to write
* @skb: the packet
* @len: the length of packet data to write as immediate data
* @gen: the generation bit value to write
*
* Writes a packet as immediate data into a Tx descriptor. The packet
* contains a work request at its beginning. We must write the packet
* carefully so the SGE doesn't read accidentally before it's written in
* its entirety.
*/
static inline void write_imm(struct tx_desc *d, struct sk_buff *skb,
unsigned int len, unsigned int gen)
{
struct work_request_hdr *from = (struct work_request_hdr *)skb->data;
struct work_request_hdr *to = (struct work_request_hdr *)d;
memcpy(&to[1], &from[1], len - sizeof(*from));
to->wr_hi = from->wr_hi | htonl(F_WR_SOP | F_WR_EOP |
V_WR_BCNTLFLT(len & 7));
wmb();
to->wr_lo = from->wr_lo | htonl(V_WR_GEN(gen) |
V_WR_LEN((len + 7) / 8));
wr_gen2(d, gen);
kfree_skb(skb);
}
/**
* check_desc_avail - check descriptor availability on a send queue
* @adap: the adapter
* @q: the send queue
* @skb: the packet needing the descriptors
* @ndesc: the number of Tx descriptors needed
* @qid: the Tx queue number in its queue set (TXQ_OFLD or TXQ_CTRL)
*
* Checks if the requested number of Tx descriptors is available on an
* SGE send queue. If the queue is already suspended or not enough
* descriptors are available the packet is queued for later transmission.
* Must be called with the Tx queue locked.
*
* Returns 0 if enough descriptors are available, 1 if there aren't
* enough descriptors and the packet has been queued, and 2 if the caller
* needs to retry because there weren't enough descriptors at the
* beginning of the call but some freed up in the mean time.
*/
static inline int check_desc_avail(struct adapter *adap, struct sge_txq *q,
struct sk_buff *skb, unsigned int ndesc,
unsigned int qid)
{
if (unlikely(!skb_queue_empty(&q->sendq))) {
addq_exit:__skb_queue_tail(&q->sendq, skb);
return 1;
}
if (unlikely(q->size - q->in_use < ndesc)) {
struct sge_qset *qs = txq_to_qset(q, qid);
set_bit(qid, &qs->txq_stopped);
smp_mb__after_clear_bit();
if (should_restart_tx(q) &&
test_and_clear_bit(qid, &qs->txq_stopped))
return 2;
q->stops++;
goto addq_exit;
}
return 0;
}
/**
* reclaim_completed_tx_imm - reclaim completed control-queue Tx descs
* @q: the SGE control Tx queue
*
* This is a variant of reclaim_completed_tx() that is used for Tx queues
* that send only immediate data (presently just the control queues) and
* thus do not have any sk_buffs to release.
*/
static inline void reclaim_completed_tx_imm(struct sge_txq *q)
{
unsigned int reclaim = q->processed - q->cleaned;
q->in_use -= reclaim;
q->cleaned += reclaim;
}
static inline int immediate(const struct sk_buff *skb)
{
return skb->len <= WR_LEN && !skb->data_len;
}
/**
* ctrl_xmit - send a packet through an SGE control Tx queue
* @adap: the adapter
* @q: the control queue
* @skb: the packet
*
* Send a packet through an SGE control Tx queue. Packets sent through
* a control queue must fit entirely as immediate data in a single Tx
* descriptor and have no page fragments.
*/
static int ctrl_xmit(struct adapter *adap, struct sge_txq *q,
struct sk_buff *skb)
{
int ret;
struct work_request_hdr *wrp = (struct work_request_hdr *)skb->data;
if (unlikely(!immediate(skb))) {
WARN_ON(1);
dev_kfree_skb(skb);
return NET_XMIT_SUCCESS;
}
wrp->wr_hi |= htonl(F_WR_SOP | F_WR_EOP);
wrp->wr_lo = htonl(V_WR_TID(q->token));
spin_lock(&q->lock);
again:reclaim_completed_tx_imm(q);
ret = check_desc_avail(adap, q, skb, 1, TXQ_CTRL);
if (unlikely(ret)) {
if (ret == 1) {
spin_unlock(&q->lock);
return NET_XMIT_CN;
}
goto again;
}
write_imm(&q->desc[q->pidx], skb, skb->len, q->gen);
q->in_use++;
if (++q->pidx >= q->size) {
q->pidx = 0;
q->gen ^= 1;
}
spin_unlock(&q->lock);
wmb();
t3_write_reg(adap, A_SG_KDOORBELL,
F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
return NET_XMIT_SUCCESS;
}
/**
* restart_ctrlq - restart a suspended control queue
* @qs: the queue set cotaining the control queue
*
* Resumes transmission on a suspended Tx control queue.
*/
static void restart_ctrlq(unsigned long data)
{
struct sk_buff *skb;
struct sge_qset *qs = (struct sge_qset *)data;
struct sge_txq *q = &qs->txq[TXQ_CTRL];
struct adapter *adap = qs->netdev->priv;
spin_lock(&q->lock);
again:reclaim_completed_tx_imm(q);
while (q->in_use < q->size && (skb = __skb_dequeue(&q->sendq)) != NULL) {
write_imm(&q->desc[q->pidx], skb, skb->len, q->gen);
if (++q->pidx >= q->size) {
q->pidx = 0;
q->gen ^= 1;
}
q->in_use++;
}
if (!skb_queue_empty(&q->sendq)) {
set_bit(TXQ_CTRL, &qs->txq_stopped);
smp_mb__after_clear_bit();
if (should_restart_tx(q) &&
test_and_clear_bit(TXQ_CTRL, &qs->txq_stopped))
goto again;
q->stops++;
}
spin_unlock(&q->lock);
t3_write_reg(adap, A_SG_KDOORBELL,
F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
}
/*
* Send a management message through control queue 0
*/
int t3_mgmt_tx(struct adapter *adap, struct sk_buff *skb)
{
return ctrl_xmit(adap, &adap->sge.qs[0].txq[TXQ_CTRL], skb);
}
/**
* deferred_unmap_destructor - unmap a packet when it is freed
* @skb: the packet
*
* This is the packet destructor used for Tx packets that need to remain
* mapped until they are freed rather than until their Tx descriptors are
* freed.
*/
static void deferred_unmap_destructor(struct sk_buff *skb)
{
int i;
const dma_addr_t *p;
const struct skb_shared_info *si;
const struct deferred_unmap_info *dui;
const struct unmap_info *ui = (struct unmap_info *)skb->cb;
dui = (struct deferred_unmap_info *)skb->head;
p = dui->addr;
if (ui->len)
pci_unmap_single(dui->pdev, *p++, ui->len, PCI_DMA_TODEVICE);
si = skb_shinfo(skb);
for (i = 0; i < si->nr_frags; i++)
pci_unmap_page(dui->pdev, *p++, si->frags[i].size,
PCI_DMA_TODEVICE);
}
static void setup_deferred_unmapping(struct sk_buff *skb, struct pci_dev *pdev,
const struct sg_ent *sgl, int sgl_flits)
{
dma_addr_t *p;
struct deferred_unmap_info *dui;
dui = (struct deferred_unmap_info *)skb->head;
dui->pdev = pdev;
for (p = dui->addr; sgl_flits >= 3; sgl++, sgl_flits -= 3) {
*p++ = be64_to_cpu(sgl->addr[0]);
*p++ = be64_to_cpu(sgl->addr[1]);
}
if (sgl_flits)
*p = be64_to_cpu(sgl->addr[0]);
}
/**
* write_ofld_wr - write an offload work request
* @adap: the adapter
* @skb: the packet to send
* @q: the Tx queue
* @pidx: index of the first Tx descriptor to write
* @gen: the generation value to use
* @ndesc: number of descriptors the packet will occupy
*
* Write an offload work request to send the supplied packet. The packet
* data already carry the work request with most fields populated.
*/
static void write_ofld_wr(struct adapter *adap, struct sk_buff *skb,
struct sge_txq *q, unsigned int pidx,
unsigned int gen, unsigned int ndesc)
{
unsigned int sgl_flits, flits;
struct work_request_hdr *from;
struct sg_ent *sgp, sgl[MAX_SKB_FRAGS / 2 + 1];
struct tx_desc *d = &q->desc[pidx];
if (immediate(skb)) {
q->sdesc[pidx].skb = NULL;
write_imm(d, skb, skb->len, gen);
return;
}
/* Only TX_DATA builds SGLs */
from = (struct work_request_hdr *)skb->data;
memcpy(&d->flit[1], &from[1], skb->h.raw - skb->data - sizeof(*from));
flits = (skb->h.raw - skb->data) / 8;
sgp = ndesc == 1 ? (struct sg_ent *)&d->flit[flits] : sgl;
sgl_flits = make_sgl(skb, sgp, skb->h.raw, skb->tail - skb->h.raw,
adap->pdev);
if (need_skb_unmap()) {
setup_deferred_unmapping(skb, adap->pdev, sgp, sgl_flits);
skb->destructor = deferred_unmap_destructor;
((struct unmap_info *)skb->cb)->len = skb->tail - skb->h.raw;
}
write_wr_hdr_sgl(ndesc, skb, d, pidx, q, sgl, flits, sgl_flits,
gen, from->wr_hi, from->wr_lo);
}
/**
* calc_tx_descs_ofld - calculate # of Tx descriptors for an offload packet
* @skb: the packet
*
* Returns the number of Tx descriptors needed for the given offload
* packet. These packets are already fully constructed.
*/
static inline unsigned int calc_tx_descs_ofld(const struct sk_buff *skb)
{
unsigned int flits, cnt = skb_shinfo(skb)->nr_frags;
if (skb->len <= WR_LEN && cnt == 0)
return 1; /* packet fits as immediate data */
flits = (skb->h.raw - skb->data) / 8; /* headers */
if (skb->tail != skb->h.raw)
cnt++;
return flits_to_desc(flits + sgl_len(cnt));
}
/**
* ofld_xmit - send a packet through an offload queue
* @adap: the adapter
* @q: the Tx offload queue
* @skb: the packet
*
* Send an offload packet through an SGE offload queue.
*/
static int ofld_xmit(struct adapter *adap, struct sge_txq *q,
struct sk_buff *skb)
{
int ret;
unsigned int ndesc = calc_tx_descs_ofld(skb), pidx, gen;
spin_lock(&q->lock);
again:reclaim_completed_tx(adap, q);
ret = check_desc_avail(adap, q, skb, ndesc, TXQ_OFLD);
if (unlikely(ret)) {
if (ret == 1) {
skb->priority = ndesc; /* save for restart */
spin_unlock(&q->lock);
return NET_XMIT_CN;
}
goto again;
}
gen = q->gen;
q->in_use += ndesc;
pidx = q->pidx;
q->pidx += ndesc;
if (q->pidx >= q->size) {
q->pidx -= q->size;
q->gen ^= 1;
}
spin_unlock(&q->lock);
write_ofld_wr(adap, skb, q, pidx, gen, ndesc);
check_ring_tx_db(adap, q);
return NET_XMIT_SUCCESS;
}
/**
* restart_offloadq - restart a suspended offload queue
* @qs: the queue set cotaining the offload queue
*
* Resumes transmission on a suspended Tx offload queue.
*/
static void restart_offloadq(unsigned long data)
{
struct sk_buff *skb;
struct sge_qset *qs = (struct sge_qset *)data;
struct sge_txq *q = &qs->txq[TXQ_OFLD];
struct adapter *adap = qs->netdev->priv;
spin_lock(&q->lock);
again:reclaim_completed_tx(adap, q);
while ((skb = skb_peek(&q->sendq)) != NULL) {
unsigned int gen, pidx;
unsigned int ndesc = skb->priority;
if (unlikely(q->size - q->in_use < ndesc)) {
set_bit(TXQ_OFLD, &qs->txq_stopped);
smp_mb__after_clear_bit();
if (should_restart_tx(q) &&
test_and_clear_bit(TXQ_OFLD, &qs->txq_stopped))
goto again;
q->stops++;
break;
}
gen = q->gen;
q->in_use += ndesc;
pidx = q->pidx;
q->pidx += ndesc;
if (q->pidx >= q->size) {
q->pidx -= q->size;
q->gen ^= 1;
}
__skb_unlink(skb, &q->sendq);
spin_unlock(&q->lock);
write_ofld_wr(adap, skb, q, pidx, gen, ndesc);
spin_lock(&q->lock);
}
spin_unlock(&q->lock);
#if USE_GTS
set_bit(TXQ_RUNNING, &q->flags);
set_bit(TXQ_LAST_PKT_DB, &q->flags);
#endif
t3_write_reg(adap, A_SG_KDOORBELL,
F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
}
/**
* queue_set - return the queue set a packet should use
* @skb: the packet
*
* Maps a packet to the SGE queue set it should use. The desired queue
* set is carried in bits 1-3 in the packet's priority.
*/
static inline int queue_set(const struct sk_buff *skb)
{
return skb->priority >> 1;
}
/**
* is_ctrl_pkt - return whether an offload packet is a control packet
* @skb: the packet
*
* Determines whether an offload packet should use an OFLD or a CTRL
* Tx queue. This is indicated by bit 0 in the packet's priority.
*/
static inline int is_ctrl_pkt(const struct sk_buff *skb)
{
return skb->priority & 1;
}
/**
* t3_offload_tx - send an offload packet
* @tdev: the offload device to send to
* @skb: the packet
*
* Sends an offload packet. We use the packet priority to select the
* appropriate Tx queue as follows: bit 0 indicates whether the packet
* should be sent as regular or control, bits 1-3 select the queue set.
*/
int t3_offload_tx(struct t3cdev *tdev, struct sk_buff *skb)
{
struct adapter *adap = tdev2adap(tdev);
struct sge_qset *qs = &adap->sge.qs[queue_set(skb)];
if (unlikely(is_ctrl_pkt(skb)))
return ctrl_xmit(adap, &qs->txq[TXQ_CTRL], skb);
return ofld_xmit(adap, &qs->txq[TXQ_OFLD], skb);
}
/**
* offload_enqueue - add an offload packet to an SGE offload receive queue
* @q: the SGE response queue
* @skb: the packet
*
* Add a new offload packet to an SGE response queue's offload packet
* queue. If the packet is the first on the queue it schedules the RX
* softirq to process the queue.
*/
static inline void offload_enqueue(struct sge_rspq *q, struct sk_buff *skb)
{
skb->next = skb->prev = NULL;
if (q->rx_tail)
q->rx_tail->next = skb;
else {
struct sge_qset *qs = rspq_to_qset(q);
if (__netif_rx_schedule_prep(qs->netdev))
__netif_rx_schedule(qs->netdev);
q->rx_head = skb;
}
q->rx_tail = skb;
}
/**
* deliver_partial_bundle - deliver a (partial) bundle of Rx offload pkts
* @tdev: the offload device that will be receiving the packets
* @q: the SGE response queue that assembled the bundle
* @skbs: the partial bundle
* @n: the number of packets in the bundle
*
* Delivers a (partial) bundle of Rx offload packets to an offload device.
*/
static inline void deliver_partial_bundle(struct t3cdev *tdev,
struct sge_rspq *q,
struct sk_buff *skbs[], int n)
{
if (n) {
q->offload_bundles++;
tdev->recv(tdev, skbs, n);
}
}
/**
* ofld_poll - NAPI handler for offload packets in interrupt mode
* @dev: the network device doing the polling
* @budget: polling budget
*
* The NAPI handler for offload packets when a response queue is serviced
* by the hard interrupt handler, i.e., when it's operating in non-polling
* mode. Creates small packet batches and sends them through the offload
* receive handler. Batches need to be of modest size as we do prefetches
* on the packets in each.
*/
static int ofld_poll(struct net_device *dev, int *budget)
{
struct adapter *adapter = dev->priv;
struct sge_qset *qs = dev2qset(dev);
struct sge_rspq *q = &qs->rspq;
int work_done, limit = min(*budget, dev->quota), avail = limit;
while (avail) {
struct sk_buff *head, *tail, *skbs[RX_BUNDLE_SIZE];
int ngathered;
spin_lock_irq(&q->lock);
head = q->rx_head;
if (!head) {
work_done = limit - avail;
*budget -= work_done;
dev->quota -= work_done;
__netif_rx_complete(dev);
spin_unlock_irq(&q->lock);
return 0;
}
tail = q->rx_tail;
q->rx_head = q->rx_tail = NULL;
spin_unlock_irq(&q->lock);
for (ngathered = 0; avail && head; avail--) {
prefetch(head->data);
skbs[ngathered] = head;
head = head->next;
skbs[ngathered]->next = NULL;
if (++ngathered == RX_BUNDLE_SIZE) {
q->offload_bundles++;
adapter->tdev.recv(&adapter->tdev, skbs,
ngathered);
ngathered = 0;
}
}
if (head) { /* splice remaining packets back onto Rx queue */
spin_lock_irq(&q->lock);
tail->next = q->rx_head;
if (!q->rx_head)
q->rx_tail = tail;
q->rx_head = head;
spin_unlock_irq(&q->lock);
}
deliver_partial_bundle(&adapter->tdev, q, skbs, ngathered);
}
work_done = limit - avail;
*budget -= work_done;
dev->quota -= work_done;
return 1;
}
/**
* rx_offload - process a received offload packet
* @tdev: the offload device receiving the packet
* @rq: the response queue that received the packet
* @skb: the packet
* @rx_gather: a gather list of packets if we are building a bundle
* @gather_idx: index of the next available slot in the bundle
*
* Process an ingress offload pakcet and add it to the offload ingress
* queue. Returns the index of the next available slot in the bundle.
*/
static inline int rx_offload(struct t3cdev *tdev, struct sge_rspq *rq,
struct sk_buff *skb, struct sk_buff *rx_gather[],
unsigned int gather_idx)
{
rq->offload_pkts++;
skb->mac.raw = skb->nh.raw = skb->h.raw = skb->data;
if (rq->polling) {
rx_gather[gather_idx++] = skb;
if (gather_idx == RX_BUNDLE_SIZE) {
tdev->recv(tdev, rx_gather, RX_BUNDLE_SIZE);
gather_idx = 0;
rq->offload_bundles++;
}
} else
offload_enqueue(rq, skb);
return gather_idx;
}
/**
* restart_tx - check whether to restart suspended Tx queues
* @qs: the queue set to resume
*
* Restarts suspended Tx queues of an SGE queue set if they have enough
* free resources to resume operation.
*/
static void restart_tx(struct sge_qset *qs)
{
if (test_bit(TXQ_ETH, &qs->txq_stopped) &&
should_restart_tx(&qs->txq[TXQ_ETH]) &&
test_and_clear_bit(TXQ_ETH, &qs->txq_stopped)) {
qs->txq[TXQ_ETH].restarts++;
if (netif_running(qs->netdev))
netif_wake_queue(qs->netdev);
}
if (test_bit(TXQ_OFLD, &qs->txq_stopped) &&
should_restart_tx(&qs->txq[TXQ_OFLD]) &&
test_and_clear_bit(TXQ_OFLD, &qs->txq_stopped)) {
qs->txq[TXQ_OFLD].restarts++;
tasklet_schedule(&qs->txq[TXQ_OFLD].qresume_tsk);
}
if (test_bit(TXQ_CTRL, &qs->txq_stopped) &&
should_restart_tx(&qs->txq[TXQ_CTRL]) &&
test_and_clear_bit(TXQ_CTRL, &qs->txq_stopped)) {
qs->txq[TXQ_CTRL].restarts++;
tasklet_schedule(&qs->txq[TXQ_CTRL].qresume_tsk);
}
}
/**
* rx_eth - process an ingress ethernet packet
* @adap: the adapter
* @rq: the response queue that received the packet
* @skb: the packet
* @pad: amount of padding at the start of the buffer
*
* Process an ingress ethernet pakcet and deliver it to the stack.
* The padding is 2 if the packet was delivered in an Rx buffer and 0
* if it was immediate data in a response.
*/
static void rx_eth(struct adapter *adap, struct sge_rspq *rq,
struct sk_buff *skb, int pad)
{
struct cpl_rx_pkt *p = (struct cpl_rx_pkt *)(skb->data + pad);
struct port_info *pi;
skb_pull(skb, sizeof(*p) + pad);
skb->dev = adap->port[p->iff];
skb->dev->last_rx = jiffies;
skb->protocol = eth_type_trans(skb, skb->dev);
pi = netdev_priv(skb->dev);
if (pi->rx_csum_offload && p->csum_valid && p->csum == 0xffff &&
!p->fragment) {
rspq_to_qset(rq)->port_stats[SGE_PSTAT_RX_CSUM_GOOD]++;
skb->ip_summed = CHECKSUM_UNNECESSARY;
} else
skb->ip_summed = CHECKSUM_NONE;
if (unlikely(p->vlan_valid)) {
struct vlan_group *grp = pi->vlan_grp;
rspq_to_qset(rq)->port_stats[SGE_PSTAT_VLANEX]++;
if (likely(grp))
__vlan_hwaccel_rx(skb, grp, ntohs(p->vlan),
rq->polling);
else
dev_kfree_skb_any(skb);
} else if (rq->polling)
netif_receive_skb(skb);
else
netif_rx(skb);
}
#define SKB_DATA_SIZE 128
static void skb_data_init(struct sk_buff *skb, struct sge_fl_page *p,
unsigned int len)
{
skb->len = len;
if (len <= SKB_DATA_SIZE) {
memcpy(skb->data, p->va, len);
skb->tail += len;
put_page(p->frag.page);
} else {
memcpy(skb->data, p->va, SKB_DATA_SIZE);
skb_shinfo(skb)->frags[0].page = p->frag.page;
skb_shinfo(skb)->frags[0].page_offset =
p->frag.page_offset + SKB_DATA_SIZE;
skb_shinfo(skb)->frags[0].size = len - SKB_DATA_SIZE;
skb_shinfo(skb)->nr_frags = 1;
skb->data_len = len - SKB_DATA_SIZE;
skb->tail += SKB_DATA_SIZE;
skb->truesize += skb->data_len;
}
}
/**
* get_packet - return the next ingress packet buffer from a free list
* @adap: the adapter that received the packet
* @fl: the SGE free list holding the packet
* @len: the packet length including any SGE padding
* @drop_thres: # of remaining buffers before we start dropping packets
*
* Get the next packet from a free list and complete setup of the
* sk_buff. If the packet is small we make a copy and recycle the
* original buffer, otherwise we use the original buffer itself. If a
* positive drop threshold is supplied packets are dropped and their
* buffers recycled if (a) the number of remaining buffers is under the
* threshold and the packet is too big to copy, or (b) the packet should
* be copied but there is no memory for the copy.
*/
static struct sk_buff *get_packet(struct adapter *adap, struct sge_fl *fl,
unsigned int len, unsigned int drop_thres)
{
struct sk_buff *skb = NULL;
struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
prefetch(sd->t.skb->data);
if (len <= SGE_RX_COPY_THRES) {
skb = alloc_skb(len, GFP_ATOMIC);
if (likely(skb != NULL)) {
struct rx_desc *d = &fl->desc[fl->cidx];
dma_addr_t mapping =
(dma_addr_t)((u64) be32_to_cpu(d->addr_hi) << 32 |
be32_to_cpu(d->addr_lo));
__skb_put(skb, len);
pci_dma_sync_single_for_cpu(adap->pdev, mapping, len,
PCI_DMA_FROMDEVICE);
memcpy(skb->data, sd->t.skb->data, len);
pci_dma_sync_single_for_device(adap->pdev, mapping, len,
PCI_DMA_FROMDEVICE);
} else if (!drop_thres)
goto use_orig_buf;
recycle:
recycle_rx_buf(adap, fl, fl->cidx);
return skb;
}
if (unlikely(fl->credits < drop_thres))
goto recycle;
use_orig_buf:
pci_unmap_single(adap->pdev, pci_unmap_addr(sd, dma_addr),
fl->buf_size, PCI_DMA_FROMDEVICE);
skb = sd->t.skb;
skb_put(skb, len);
__refill_fl(adap, fl);
return skb;
}
/**
* handle_rsp_cntrl_info - handles control information in a response
* @qs: the queue set corresponding to the response
* @flags: the response control flags
*
* Handles the control information of an SGE response, such as GTS
* indications and completion credits for the queue set's Tx queues.
* HW coalesces credits, we don't do any extra SW coalescing.
*/
static inline void handle_rsp_cntrl_info(struct sge_qset *qs, u32 flags)
{
unsigned int credits;
#if USE_GTS
if (flags & F_RSPD_TXQ0_GTS)
clear_bit(TXQ_RUNNING, &qs->txq[TXQ_ETH].flags);
#endif
credits = G_RSPD_TXQ0_CR(flags);
if (credits)
qs->txq[TXQ_ETH].processed += credits;
credits = G_RSPD_TXQ2_CR(flags);
if (credits)
qs->txq[TXQ_CTRL].processed += credits;
# if USE_GTS
if (flags & F_RSPD_TXQ1_GTS)
clear_bit(TXQ_RUNNING, &qs->txq[TXQ_OFLD].flags);
# endif
credits = G_RSPD_TXQ1_CR(flags);
if (credits)
qs->txq[TXQ_OFLD].processed += credits;
}
/**
* check_ring_db - check if we need to ring any doorbells
* @adapter: the adapter
* @qs: the queue set whose Tx queues are to be examined
* @sleeping: indicates which Tx queue sent GTS
*
* Checks if some of a queue set's Tx queues need to ring their doorbells
* to resume transmission after idling while they still have unprocessed
* descriptors.
*/
static void check_ring_db(struct adapter *adap, struct sge_qset *qs,
unsigned int sleeping)
{
if (sleeping & F_RSPD_TXQ0_GTS) {
struct sge_txq *txq = &qs->txq[TXQ_ETH];
if (txq->cleaned + txq->in_use != txq->processed &&
!test_and_set_bit(TXQ_LAST_PKT_DB, &txq->flags)) {
set_bit(TXQ_RUNNING, &txq->flags);
t3_write_reg(adap, A_SG_KDOORBELL, F_SELEGRCNTX |
V_EGRCNTX(txq->cntxt_id));
}
}
if (sleeping & F_RSPD_TXQ1_GTS) {
struct sge_txq *txq = &qs->txq[TXQ_OFLD];
if (txq->cleaned + txq->in_use != txq->processed &&
!test_and_set_bit(TXQ_LAST_PKT_DB, &txq->flags)) {
set_bit(TXQ_RUNNING, &txq->flags);
t3_write_reg(adap, A_SG_KDOORBELL, F_SELEGRCNTX |
V_EGRCNTX(txq->cntxt_id));
}
}
}
/**
* is_new_response - check if a response is newly written
* @r: the response descriptor
* @q: the response queue
*
* Returns true if a response descriptor contains a yet unprocessed
* response.
*/
static inline int is_new_response(const struct rsp_desc *r,
const struct sge_rspq *q)
{
return (r->intr_gen & F_RSPD_GEN2) == q->gen;
}
#define RSPD_GTS_MASK (F_RSPD_TXQ0_GTS | F_RSPD_TXQ1_GTS)
#define RSPD_CTRL_MASK (RSPD_GTS_MASK | \
V_RSPD_TXQ0_CR(M_RSPD_TXQ0_CR) | \
V_RSPD_TXQ1_CR(M_RSPD_TXQ1_CR) | \
V_RSPD_TXQ2_CR(M_RSPD_TXQ2_CR))
/* How long to delay the next interrupt in case of memory shortage, in 0.1us. */
#define NOMEM_INTR_DELAY 2500
/**
* process_responses - process responses from an SGE response queue
* @adap: the adapter
* @qs: the queue set to which the response queue belongs
* @budget: how many responses can be processed in this round
*
* Process responses from an SGE response queue up to the supplied budget.
* Responses include received packets as well as credits and other events
* for the queues that belong to the response queue's queue set.
* A negative budget is effectively unlimited.
*
* Additionally choose the interrupt holdoff time for the next interrupt
* on this queue. If the system is under memory shortage use a fairly
* long delay to help recovery.
*/
static int process_responses(struct adapter *adap, struct sge_qset *qs,
int budget)
{
struct sge_rspq *q = &qs->rspq;
struct rsp_desc *r = &q->desc[q->cidx];
int budget_left = budget;
unsigned int sleeping = 0;
struct sk_buff *offload_skbs[RX_BUNDLE_SIZE];
int ngathered = 0;
q->next_holdoff = q->holdoff_tmr;
while (likely(budget_left && is_new_response(r, q))) {
int eth, ethpad = 2;
struct sk_buff *skb = NULL;
u32 len, flags = ntohl(r->flags);
u32 rss_hi = *(const u32 *)r, rss_lo = r->rss_hdr.rss_hash_val;
eth = r->rss_hdr.opcode == CPL_RX_PKT;
if (unlikely(flags & F_RSPD_ASYNC_NOTIF)) {
skb = alloc_skb(AN_PKT_SIZE, GFP_ATOMIC);
if (!skb)
goto no_mem;
memcpy(__skb_put(skb, AN_PKT_SIZE), r, AN_PKT_SIZE);
skb->data[0] = CPL_ASYNC_NOTIF;
rss_hi = htonl(CPL_ASYNC_NOTIF << 24);
q->async_notif++;
} else if (flags & F_RSPD_IMM_DATA_VALID) {
skb = get_imm_packet(r);
if (unlikely(!skb)) {
no_mem:
q->next_holdoff = NOMEM_INTR_DELAY;
q->nomem++;
/* consume one credit since we tried */
budget_left--;
break;
}
q->imm_data++;
ethpad = 0;
} else if ((len = ntohl(r->len_cq)) != 0) {
struct sge_fl *fl =
(len & F_RSPD_FLQ) ? &qs->fl[1] : &qs->fl[0];
if (fl->buf_size == RX_PAGE_SIZE) {
struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
struct sge_fl_page *p = &sd->t.page;
prefetch(p->va);
prefetch(p->va + L1_CACHE_BYTES);
__refill_fl(adap, fl);
pci_unmap_single(adap->pdev,
pci_unmap_addr(sd, dma_addr),
fl->buf_size,
PCI_DMA_FROMDEVICE);
if (eth) {
if (unlikely(fl->credits <
SGE_RX_DROP_THRES))
goto eth_recycle;
skb = alloc_skb(SKB_DATA_SIZE,
GFP_ATOMIC);
if (unlikely(!skb)) {
eth_recycle:
q->rx_drops++;
recycle_rx_buf(adap, fl,
fl->cidx);
goto eth_done;
}
} else {
skb = alloc_skb(SKB_DATA_SIZE,
GFP_ATOMIC);
if (unlikely(!skb))
goto no_mem;
}
skb_data_init(skb, p, G_RSPD_LEN(len));
eth_done:
fl->credits--;
q->eth_pkts++;
} else {
fl->credits--;
skb = get_packet(adap, fl, G_RSPD_LEN(len),
eth ? SGE_RX_DROP_THRES : 0);
}
if (++fl->cidx == fl->size)
fl->cidx = 0;
} else
q->pure_rsps++;
if (flags & RSPD_CTRL_MASK) {
sleeping |= flags & RSPD_GTS_MASK;
handle_rsp_cntrl_info(qs, flags);
}
r++;
if (unlikely(++q->cidx == q->size)) {
q->cidx = 0;
q->gen ^= 1;
r = q->desc;
}
prefetch(r);
if (++q->credits >= (q->size / 4)) {
refill_rspq(adap, q, q->credits);
q->credits = 0;
}
if (skb) {
/* Preserve the RSS info in csum & priority */
skb->csum = rss_hi;
skb->priority = rss_lo;
if (eth)
rx_eth(adap, q, skb, ethpad);
else {
if (unlikely(r->rss_hdr.opcode ==
CPL_TRACE_PKT))
__skb_pull(skb, ethpad);
ngathered = rx_offload(&adap->tdev, q,
skb, offload_skbs,
ngathered);
}
}
--budget_left;
}
deliver_partial_bundle(&adap->tdev, q, offload_skbs, ngathered);
if (sleeping)
check_ring_db(adap, qs, sleeping);
smp_mb(); /* commit Tx queue .processed updates */
if (unlikely(qs->txq_stopped != 0))
restart_tx(qs);
budget -= budget_left;
return budget;
}
static inline int is_pure_response(const struct rsp_desc *r)
{
u32 n = ntohl(r->flags) & (F_RSPD_ASYNC_NOTIF | F_RSPD_IMM_DATA_VALID);
return (n | r->len_cq) == 0;
}
/**
* napi_rx_handler - the NAPI handler for Rx processing
* @dev: the net device
* @budget: how many packets we can process in this round
*
* Handler for new data events when using NAPI.
*/
static int napi_rx_handler(struct net_device *dev, int *budget)
{
struct adapter *adap = dev->priv;
struct sge_qset *qs = dev2qset(dev);
int effective_budget = min(*budget, dev->quota);
int work_done = process_responses(adap, qs, effective_budget);
*budget -= work_done;
dev->quota -= work_done;
if (work_done >= effective_budget)
return 1;
netif_rx_complete(dev);
/*
* Because we don't atomically flush the following write it is
* possible that in very rare cases it can reach the device in a way
* that races with a new response being written plus an error interrupt
* causing the NAPI interrupt handler below to return unhandled status
* to the OS. To protect against this would require flushing the write
* and doing both the write and the flush with interrupts off. Way too
* expensive and unjustifiable given the rarity of the race.
*
* The race cannot happen at all with MSI-X.
*/
t3_write_reg(adap, A_SG_GTS, V_RSPQ(qs->rspq.cntxt_id) |
V_NEWTIMER(qs->rspq.next_holdoff) |
V_NEWINDEX(qs->rspq.cidx));
return 0;
}
/*
* Returns true if the device is already scheduled for polling.
*/
static inline int napi_is_scheduled(struct net_device *dev)
{
return test_bit(__LINK_STATE_RX_SCHED, &dev->state);
}
/**
* process_pure_responses - process pure responses from a response queue
* @adap: the adapter
* @qs: the queue set owning the response queue
* @r: the first pure response to process
*
* A simpler version of process_responses() that handles only pure (i.e.,
* non data-carrying) responses. Such respones are too light-weight to
* justify calling a softirq under NAPI, so we handle them specially in
* the interrupt handler. The function is called with a pointer to a
* response, which the caller must ensure is a valid pure response.
*
* Returns 1 if it encounters a valid data-carrying response, 0 otherwise.
*/
static int process_pure_responses(struct adapter *adap, struct sge_qset *qs,
struct rsp_desc *r)
{
struct sge_rspq *q = &qs->rspq;
unsigned int sleeping = 0;
do {
u32 flags = ntohl(r->flags);
r++;
if (unlikely(++q->cidx == q->size)) {
q->cidx = 0;
q->gen ^= 1;
r = q->desc;
}
prefetch(r);
if (flags & RSPD_CTRL_MASK) {
sleeping |= flags & RSPD_GTS_MASK;
handle_rsp_cntrl_info(qs, flags);
}
q->pure_rsps++;
if (++q->credits >= (q->size / 4)) {
refill_rspq(adap, q, q->credits);
q->credits = 0;
}
} while (is_new_response(r, q) && is_pure_response(r));
if (sleeping)
check_ring_db(adap, qs, sleeping);
smp_mb(); /* commit Tx queue .processed updates */
if (unlikely(qs->txq_stopped != 0))
restart_tx(qs);
return is_new_response(r, q);
}
/**
* handle_responses - decide what to do with new responses in NAPI mode
* @adap: the adapter
* @q: the response queue
*
* This is used by the NAPI interrupt handlers to decide what to do with
* new SGE responses. If there are no new responses it returns -1. If
* there are new responses and they are pure (i.e., non-data carrying)
* it handles them straight in hard interrupt context as they are very
* cheap and don't deliver any packets. Finally, if there are any data
* signaling responses it schedules the NAPI handler. Returns 1 if it
* schedules NAPI, 0 if all new responses were pure.
*
* The caller must ascertain NAPI is not already running.
*/
static inline int handle_responses(struct adapter *adap, struct sge_rspq *q)
{
struct sge_qset *qs = rspq_to_qset(q);
struct rsp_desc *r = &q->desc[q->cidx];
if (!is_new_response(r, q))
return -1;
if (is_pure_response(r) && process_pure_responses(adap, qs, r) == 0) {
t3_write_reg(adap, A_SG_GTS, V_RSPQ(q->cntxt_id) |
V_NEWTIMER(q->holdoff_tmr) | V_NEWINDEX(q->cidx));
return 0;
}
if (likely(__netif_rx_schedule_prep(qs->netdev)))
__netif_rx_schedule(qs->netdev);
return 1;
}
/*
* The MSI-X interrupt handler for an SGE response queue for the non-NAPI case
* (i.e., response queue serviced in hard interrupt).
*/
irqreturn_t t3_sge_intr_msix(int irq, void *cookie)
{
struct sge_qset *qs = cookie;
struct adapter *adap = qs->netdev->priv;
struct sge_rspq *q = &qs->rspq;
spin_lock(&q->lock);
if (process_responses(adap, qs, -1) == 0)
q->unhandled_irqs++;
t3_write_reg(adap, A_SG_GTS, V_RSPQ(q->cntxt_id) |
V_NEWTIMER(q->next_holdoff) | V_NEWINDEX(q->cidx));
spin_unlock(&q->lock);
return IRQ_HANDLED;
}
/*
* The MSI-X interrupt handler for an SGE response queue for the NAPI case
* (i.e., response queue serviced by NAPI polling).
*/
irqreturn_t t3_sge_intr_msix_napi(int irq, void *cookie)
{
struct sge_qset *qs = cookie;
struct adapter *adap = qs->netdev->priv;
struct sge_rspq *q = &qs->rspq;
spin_lock(&q->lock);
BUG_ON(napi_is_scheduled(qs->netdev));
if (handle_responses(adap, q) < 0)
q->unhandled_irqs++;
spin_unlock(&q->lock);
return IRQ_HANDLED;
}
/*
* The non-NAPI MSI interrupt handler. This needs to handle data events from
* SGE response queues as well as error and other async events as they all use
* the same MSI vector. We use one SGE response queue per port in this mode
* and protect all response queues with queue 0's lock.
*/
static irqreturn_t t3_intr_msi(int irq, void *cookie)
{
int new_packets = 0;
struct adapter *adap = cookie;
struct sge_rspq *q = &adap->sge.qs[0].rspq;
spin_lock(&q->lock);
if (process_responses(adap, &adap->sge.qs[0], -1)) {
t3_write_reg(adap, A_SG_GTS, V_RSPQ(q->cntxt_id) |
V_NEWTIMER(q->next_holdoff) | V_NEWINDEX(q->cidx));
new_packets = 1;
}
if (adap->params.nports == 2 &&
process_responses(adap, &adap->sge.qs[1], -1)) {
struct sge_rspq *q1 = &adap->sge.qs[1].rspq;
t3_write_reg(adap, A_SG_GTS, V_RSPQ(q1->cntxt_id) |
V_NEWTIMER(q1->next_holdoff) |
V_NEWINDEX(q1->cidx));
new_packets = 1;
}
if (!new_packets && t3_slow_intr_handler(adap) == 0)
q->unhandled_irqs++;
spin_unlock(&q->lock);
return IRQ_HANDLED;
}
static int rspq_check_napi(struct net_device *dev, struct sge_rspq *q)
{
if (!napi_is_scheduled(dev) && is_new_response(&q->desc[q->cidx], q)) {
if (likely(__netif_rx_schedule_prep(dev)))
__netif_rx_schedule(dev);
return 1;
}
return 0;
}
/*
* The MSI interrupt handler for the NAPI case (i.e., response queues serviced
* by NAPI polling). Handles data events from SGE response queues as well as
* error and other async events as they all use the same MSI vector. We use
* one SGE response queue per port in this mode and protect all response
* queues with queue 0's lock.
*/
irqreturn_t t3_intr_msi_napi(int irq, void *cookie)
{
int new_packets;
struct adapter *adap = cookie;
struct sge_rspq *q = &adap->sge.qs[0].rspq;
spin_lock(&q->lock);
new_packets = rspq_check_napi(adap->sge.qs[0].netdev, q);
if (adap->params.nports == 2)
new_packets += rspq_check_napi(adap->sge.qs[1].netdev,
&adap->sge.qs[1].rspq);
if (!new_packets && t3_slow_intr_handler(adap) == 0)
q->unhandled_irqs++;
spin_unlock(&q->lock);
return IRQ_HANDLED;
}
/*
* A helper function that processes responses and issues GTS.
*/
static inline int process_responses_gts(struct adapter *adap,
struct sge_rspq *rq)
{
int work;
work = process_responses(adap, rspq_to_qset(rq), -1);
t3_write_reg(adap, A_SG_GTS, V_RSPQ(rq->cntxt_id) |
V_NEWTIMER(rq->next_holdoff) | V_NEWINDEX(rq->cidx));
return work;
}
/*
* The legacy INTx interrupt handler. This needs to handle data events from
* SGE response queues as well as error and other async events as they all use
* the same interrupt pin. We use one SGE response queue per port in this mode
* and protect all response queues with queue 0's lock.
*/
static irqreturn_t t3_intr(int irq, void *cookie)
{
int work_done, w0, w1;
struct adapter *adap = cookie;
struct sge_rspq *q0 = &adap->sge.qs[0].rspq;
struct sge_rspq *q1 = &adap->sge.qs[1].rspq;
spin_lock(&q0->lock);
w0 = is_new_response(&q0->desc[q0->cidx], q0);
w1 = adap->params.nports == 2 &&
is_new_response(&q1->desc[q1->cidx], q1);
if (likely(w0 | w1)) {
t3_write_reg(adap, A_PL_CLI, 0);
t3_read_reg(adap, A_PL_CLI); /* flush */
if (likely(w0))
process_responses_gts(adap, q0);
if (w1)
process_responses_gts(adap, q1);
work_done = w0 | w1;
} else
work_done = t3_slow_intr_handler(adap);
spin_unlock(&q0->lock);
return IRQ_RETVAL(work_done != 0);
}
/*
* Interrupt handler for legacy INTx interrupts for T3B-based cards.
* Handles data events from SGE response queues as well as error and other
* async events as they all use the same interrupt pin. We use one SGE
* response queue per port in this mode and protect all response queues with
* queue 0's lock.
*/
static irqreturn_t t3b_intr(int irq, void *cookie)
{
u32 map;
struct adapter *adap = cookie;
struct sge_rspq *q0 = &adap->sge.qs[0].rspq;
t3_write_reg(adap, A_PL_CLI, 0);
map = t3_read_reg(adap, A_SG_DATA_INTR);
if (unlikely(!map)) /* shared interrupt, most likely */
return IRQ_NONE;
spin_lock(&q0->lock);
if (unlikely(map & F_ERRINTR))
t3_slow_intr_handler(adap);
if (likely(map & 1))
process_responses_gts(adap, q0);
if (map & 2)
process_responses_gts(adap, &adap->sge.qs[1].rspq);
spin_unlock(&q0->lock);
return IRQ_HANDLED;
}
/*
* NAPI interrupt handler for legacy INTx interrupts for T3B-based cards.
* Handles data events from SGE response queues as well as error and other
* async events as they all use the same interrupt pin. We use one SGE
* response queue per port in this mode and protect all response queues with
* queue 0's lock.
*/
static irqreturn_t t3b_intr_napi(int irq, void *cookie)
{
u32 map;
struct net_device *dev;
struct adapter *adap = cookie;
struct sge_rspq *q0 = &adap->sge.qs[0].rspq;
t3_write_reg(adap, A_PL_CLI, 0);
map = t3_read_reg(adap, A_SG_DATA_INTR);
if (unlikely(!map)) /* shared interrupt, most likely */
return IRQ_NONE;
spin_lock(&q0->lock);
if (unlikely(map & F_ERRINTR))
t3_slow_intr_handler(adap);
if (likely(map & 1)) {
dev = adap->sge.qs[0].netdev;
if (likely(__netif_rx_schedule_prep(dev)))
__netif_rx_schedule(dev);
}
if (map & 2) {
dev = adap->sge.qs[1].netdev;
if (likely(__netif_rx_schedule_prep(dev)))
__netif_rx_schedule(dev);
}
spin_unlock(&q0->lock);
return IRQ_HANDLED;
}
/**
* t3_intr_handler - select the top-level interrupt handler
* @adap: the adapter
* @polling: whether using NAPI to service response queues
*
* Selects the top-level interrupt handler based on the type of interrupts
* (MSI-X, MSI, or legacy) and whether NAPI will be used to service the
* response queues.
*/
intr_handler_t t3_intr_handler(struct adapter *adap, int polling)
{
if (adap->flags & USING_MSIX)
return polling ? t3_sge_intr_msix_napi : t3_sge_intr_msix;
if (adap->flags & USING_MSI)
return polling ? t3_intr_msi_napi : t3_intr_msi;
if (adap->params.rev > 0)
return polling ? t3b_intr_napi : t3b_intr;
return t3_intr;
}
/**
* t3_sge_err_intr_handler - SGE async event interrupt handler
* @adapter: the adapter
*
* Interrupt handler for SGE asynchronous (non-data) events.
*/
void t3_sge_err_intr_handler(struct adapter *adapter)
{
unsigned int v, status = t3_read_reg(adapter, A_SG_INT_CAUSE);
if (status & F_RSPQCREDITOVERFOW)
CH_ALERT(adapter, "SGE response queue credit overflow\n");
if (status & F_RSPQDISABLED) {
v = t3_read_reg(adapter, A_SG_RSPQ_FL_STATUS);
CH_ALERT(adapter,
"packet delivered to disabled response queue "
"(0x%x)\n", (v >> S_RSPQ0DISABLED) & 0xff);
}
t3_write_reg(adapter, A_SG_INT_CAUSE, status);
if (status & (F_RSPQCREDITOVERFOW | F_RSPQDISABLED))
t3_fatal_err(adapter);
}
/**
* sge_timer_cb - perform periodic maintenance of an SGE qset
* @data: the SGE queue set to maintain
*
* Runs periodically from a timer to perform maintenance of an SGE queue
* set. It performs two tasks:
*
* a) Cleans up any completed Tx descriptors that may still be pending.
* Normal descriptor cleanup happens when new packets are added to a Tx
* queue so this timer is relatively infrequent and does any cleanup only
* if the Tx queue has not seen any new packets in a while. We make a
* best effort attempt to reclaim descriptors, in that we don't wait
* around if we cannot get a queue's lock (which most likely is because
* someone else is queueing new packets and so will also handle the clean
* up). Since control queues use immediate data exclusively we don't
* bother cleaning them up here.
*
* b) Replenishes Rx queues that have run out due to memory shortage.
* Normally new Rx buffers are added when existing ones are consumed but
* when out of memory a queue can become empty. We try to add only a few
* buffers here, the queue will be replenished fully as these new buffers
* are used up if memory shortage has subsided.
*/
static void sge_timer_cb(unsigned long data)
{
spinlock_t *lock;
struct sge_qset *qs = (struct sge_qset *)data;
struct adapter *adap = qs->netdev->priv;
if (spin_trylock(&qs->txq[TXQ_ETH].lock)) {
reclaim_completed_tx(adap, &qs->txq[TXQ_ETH]);
spin_unlock(&qs->txq[TXQ_ETH].lock);
}
if (spin_trylock(&qs->txq[TXQ_OFLD].lock)) {
reclaim_completed_tx(adap, &qs->txq[TXQ_OFLD]);
spin_unlock(&qs->txq[TXQ_OFLD].lock);
}
lock = (adap->flags & USING_MSIX) ? &qs->rspq.lock :
&adap->sge.qs[0].rspq.lock;
if (spin_trylock_irq(lock)) {
if (!napi_is_scheduled(qs->netdev)) {
u32 status = t3_read_reg(adap, A_SG_RSPQ_FL_STATUS);
if (qs->fl[0].credits < qs->fl[0].size)
__refill_fl(adap, &qs->fl[0]);
if (qs->fl[1].credits < qs->fl[1].size)
__refill_fl(adap, &qs->fl[1]);
if (status & (1 << qs->rspq.cntxt_id)) {
qs->rspq.starved++;
if (qs->rspq.credits) {
refill_rspq(adap, &qs->rspq, 1);
qs->rspq.credits--;
qs->rspq.restarted++;
t3_write_reg(adap, A_SG_RSPQ_FL_STATUS,
1 << qs->rspq.cntxt_id);
}
}
}
spin_unlock_irq(lock);
}
mod_timer(&qs->tx_reclaim_timer, jiffies + TX_RECLAIM_PERIOD);
}
/**
* t3_update_qset_coalesce - update coalescing settings for a queue set
* @qs: the SGE queue set
* @p: new queue set parameters
*
* Update the coalescing settings for an SGE queue set. Nothing is done
* if the queue set is not initialized yet.
*/
void t3_update_qset_coalesce(struct sge_qset *qs, const struct qset_params *p)
{
if (!qs->netdev)
return;
qs->rspq.holdoff_tmr = max(p->coalesce_usecs * 10, 1U);/* can't be 0 */
qs->rspq.polling = p->polling;
qs->netdev->poll = p->polling ? napi_rx_handler : ofld_poll;
}
/**
* t3_sge_alloc_qset - initialize an SGE queue set
* @adapter: the adapter
* @id: the queue set id
* @nports: how many Ethernet ports will be using this queue set
* @irq_vec_idx: the IRQ vector index for response queue interrupts
* @p: configuration parameters for this queue set
* @ntxq: number of Tx queues for the queue set
* @netdev: net device associated with this queue set
*
* Allocate resources and initialize an SGE queue set. A queue set
* comprises a response queue, two Rx free-buffer queues, and up to 3
* Tx queues. The Tx queues are assigned roles in the order Ethernet
* queue, offload queue, and control queue.
*/
int t3_sge_alloc_qset(struct adapter *adapter, unsigned int id, int nports,
int irq_vec_idx, const struct qset_params *p,
int ntxq, struct net_device *netdev)
{
int i, ret = -ENOMEM;
struct sge_qset *q = &adapter->sge.qs[id];
init_qset_cntxt(q, id);
init_timer(&q->tx_reclaim_timer);
q->tx_reclaim_timer.data = (unsigned long)q;
q->tx_reclaim_timer.function = sge_timer_cb;
q->fl[0].desc = alloc_ring(adapter->pdev, p->fl_size,
sizeof(struct rx_desc),
sizeof(struct rx_sw_desc),
&q->fl[0].phys_addr, &q->fl[0].sdesc);
if (!q->fl[0].desc)
goto err;
q->fl[1].desc = alloc_ring(adapter->pdev, p->jumbo_size,
sizeof(struct rx_desc),
sizeof(struct rx_sw_desc),
&q->fl[1].phys_addr, &q->fl[1].sdesc);
if (!q->fl[1].desc)
goto err;
q->rspq.desc = alloc_ring(adapter->pdev, p->rspq_size,
sizeof(struct rsp_desc), 0,
&q->rspq.phys_addr, NULL);
if (!q->rspq.desc)
goto err;
for (i = 0; i < ntxq; ++i) {
/*
* The control queue always uses immediate data so does not
* need to keep track of any sk_buffs.
*/
size_t sz = i == TXQ_CTRL ? 0 : sizeof(struct tx_sw_desc);
q->txq[i].desc = alloc_ring(adapter->pdev, p->txq_size[i],
sizeof(struct tx_desc), sz,
&q->txq[i].phys_addr,
&q->txq[i].sdesc);
if (!q->txq[i].desc)
goto err;
q->txq[i].gen = 1;
q->txq[i].size = p->txq_size[i];
spin_lock_init(&q->txq[i].lock);
skb_queue_head_init(&q->txq[i].sendq);
}
tasklet_init(&q->txq[TXQ_OFLD].qresume_tsk, restart_offloadq,
(unsigned long)q);
tasklet_init(&q->txq[TXQ_CTRL].qresume_tsk, restart_ctrlq,
(unsigned long)q);
q->fl[0].gen = q->fl[1].gen = 1;
q->fl[0].size = p->fl_size;
q->fl[1].size = p->jumbo_size;
q->rspq.gen = 1;
q->rspq.size = p->rspq_size;
spin_lock_init(&q->rspq.lock);
q->txq[TXQ_ETH].stop_thres = nports *
flits_to_desc(sgl_len(MAX_SKB_FRAGS + 1) + 3);
if (ntxq == 1) {
#ifdef USE_RX_PAGE
q->fl[0].buf_size = RX_PAGE_SIZE;
#else
q->fl[0].buf_size = SGE_RX_SM_BUF_SIZE + 2 +
sizeof(struct cpl_rx_pkt);
#endif
q->fl[1].buf_size = MAX_FRAME_SIZE + 2 +
sizeof(struct cpl_rx_pkt);
} else {
#ifdef USE_RX_PAGE
q->fl[0].buf_size = RX_PAGE_SIZE;
#else
q->fl[0].buf_size = SGE_RX_SM_BUF_SIZE +
sizeof(struct cpl_rx_data);
#endif
q->fl[1].buf_size = (16 * 1024) -
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
}
spin_lock(&adapter->sge.reg_lock);
/* FL threshold comparison uses < */
ret = t3_sge_init_rspcntxt(adapter, q->rspq.cntxt_id, irq_vec_idx,
q->rspq.phys_addr, q->rspq.size,
q->fl[0].buf_size, 1, 0);
if (ret)
goto err_unlock;
for (i = 0; i < SGE_RXQ_PER_SET; ++i) {
ret = t3_sge_init_flcntxt(adapter, q->fl[i].cntxt_id, 0,
q->fl[i].phys_addr, q->fl[i].size,
q->fl[i].buf_size, p->cong_thres, 1,
0);
if (ret)
goto err_unlock;
}
ret = t3_sge_init_ecntxt(adapter, q->txq[TXQ_ETH].cntxt_id, USE_GTS,
SGE_CNTXT_ETH, id, q->txq[TXQ_ETH].phys_addr,
q->txq[TXQ_ETH].size, q->txq[TXQ_ETH].token,
1, 0);
if (ret)
goto err_unlock;
if (ntxq > 1) {
ret = t3_sge_init_ecntxt(adapter, q->txq[TXQ_OFLD].cntxt_id,
USE_GTS, SGE_CNTXT_OFLD, id,
q->txq[TXQ_OFLD].phys_addr,
q->txq[TXQ_OFLD].size, 0, 1, 0);
if (ret)
goto err_unlock;
}
if (ntxq > 2) {
ret = t3_sge_init_ecntxt(adapter, q->txq[TXQ_CTRL].cntxt_id, 0,
SGE_CNTXT_CTRL, id,
q->txq[TXQ_CTRL].phys_addr,
q->txq[TXQ_CTRL].size,
q->txq[TXQ_CTRL].token, 1, 0);
if (ret)
goto err_unlock;
}
spin_unlock(&adapter->sge.reg_lock);
q->netdev = netdev;
t3_update_qset_coalesce(q, p);
/*
* We use atalk_ptr as a backpointer to a qset. In case a device is
* associated with multiple queue sets only the first one sets
* atalk_ptr.
*/
if (netdev->atalk_ptr == NULL)
netdev->atalk_ptr = q;
refill_fl(adapter, &q->fl[0], q->fl[0].size, GFP_KERNEL);
refill_fl(adapter, &q->fl[1], q->fl[1].size, GFP_KERNEL);
refill_rspq(adapter, &q->rspq, q->rspq.size - 1);
t3_write_reg(adapter, A_SG_GTS, V_RSPQ(q->rspq.cntxt_id) |
V_NEWTIMER(q->rspq.holdoff_tmr));
mod_timer(&q->tx_reclaim_timer, jiffies + TX_RECLAIM_PERIOD);
return 0;
err_unlock:
spin_unlock(&adapter->sge.reg_lock);
err:
t3_free_qset(adapter, q);
return ret;
}
/**
* t3_free_sge_resources - free SGE resources
* @adap: the adapter
*
* Frees resources used by the SGE queue sets.
*/
void t3_free_sge_resources(struct adapter *adap)
{
int i;
for (i = 0; i < SGE_QSETS; ++i)
t3_free_qset(adap, &adap->sge.qs[i]);
}
/**
* t3_sge_start - enable SGE
* @adap: the adapter
*
* Enables the SGE for DMAs. This is the last step in starting packet
* transfers.
*/
void t3_sge_start(struct adapter *adap)
{
t3_set_reg_field(adap, A_SG_CONTROL, F_GLOBALENABLE, F_GLOBALENABLE);
}
/**
* t3_sge_stop - disable SGE operation
* @adap: the adapter
*
* Disables the DMA engine. This can be called in emeregencies (e.g.,
* from error interrupts) or from normal process context. In the latter
* case it also disables any pending queue restart tasklets. Note that
* if it is called in interrupt context it cannot disable the restart
* tasklets as it cannot wait, however the tasklets will have no effect
* since the doorbells are disabled and the driver will call this again
* later from process context, at which time the tasklets will be stopped
* if they are still running.
*/
void t3_sge_stop(struct adapter *adap)
{
t3_set_reg_field(adap, A_SG_CONTROL, F_GLOBALENABLE, 0);
if (!in_interrupt()) {
int i;
for (i = 0; i < SGE_QSETS; ++i) {
struct sge_qset *qs = &adap->sge.qs[i];
tasklet_kill(&qs->txq[TXQ_OFLD].qresume_tsk);
tasklet_kill(&qs->txq[TXQ_CTRL].qresume_tsk);
}
}
}
/**
* t3_sge_init - initialize SGE
* @adap: the adapter
* @p: the SGE parameters
*
* Performs SGE initialization needed every time after a chip reset.
* We do not initialize any of the queue sets here, instead the driver
* top-level must request those individually. We also do not enable DMA
* here, that should be done after the queues have been set up.
*/
void t3_sge_init(struct adapter *adap, struct sge_params *p)
{
unsigned int ctrl, ups = ffs(pci_resource_len(adap->pdev, 2) >> 12);
ctrl = F_DROPPKT | V_PKTSHIFT(2) | F_FLMODE | F_AVOIDCQOVFL |
F_CQCRDTCTRL |
V_HOSTPAGESIZE(PAGE_SHIFT - 11) | F_BIGENDIANINGRESS |
V_USERSPACESIZE(ups ? ups - 1 : 0) | F_ISCSICOALESCING;
#if SGE_NUM_GENBITS == 1
ctrl |= F_EGRGENCTRL;
#endif
if (adap->params.rev > 0) {
if (!(adap->flags & (USING_MSIX | USING_MSI)))
ctrl |= F_ONEINTMULTQ | F_OPTONEINTMULTQ;
ctrl |= F_CQCRDTCTRL | F_AVOIDCQOVFL;
}
t3_write_reg(adap, A_SG_CONTROL, ctrl);
t3_write_reg(adap, A_SG_EGR_RCQ_DRB_THRSH, V_HIRCQDRBTHRSH(512) |
V_LORCQDRBTHRSH(512));
t3_write_reg(adap, A_SG_TIMER_TICK, core_ticks_per_usec(adap) / 10);
t3_write_reg(adap, A_SG_CMDQ_CREDIT_TH, V_THRESHOLD(32) |
V_TIMEOUT(200 * core_ticks_per_usec(adap)));
t3_write_reg(adap, A_SG_HI_DRB_HI_THRSH, 1000);
t3_write_reg(adap, A_SG_HI_DRB_LO_THRSH, 256);
t3_write_reg(adap, A_SG_LO_DRB_HI_THRSH, 1000);
t3_write_reg(adap, A_SG_LO_DRB_LO_THRSH, 256);
t3_write_reg(adap, A_SG_OCO_BASE, V_BASE1(0xfff));
t3_write_reg(adap, A_SG_DRB_PRI_THRESH, 63 * 1024);
}
/**
* t3_sge_prep - one-time SGE initialization
* @adap: the associated adapter
* @p: SGE parameters
*
* Performs one-time initialization of SGE SW state. Includes determining
* defaults for the assorted SGE parameters, which admins can change until
* they are used to initialize the SGE.
*/
void __devinit t3_sge_prep(struct adapter *adap, struct sge_params *p)
{
int i;
p->max_pkt_size = (16 * 1024) - sizeof(struct cpl_rx_data) -
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
for (i = 0; i < SGE_QSETS; ++i) {
struct qset_params *q = p->qset + i;
q->polling = adap->params.rev > 0;
q->coalesce_usecs = 5;
q->rspq_size = 1024;
q->fl_size = 1024;
q->jumbo_size = 512;
q->txq_size[TXQ_ETH] = 1024;
q->txq_size[TXQ_OFLD] = 1024;
q->txq_size[TXQ_CTRL] = 256;
q->cong_thres = 0;
}
spin_lock_init(&adap->sge.reg_lock);
}
/**
* t3_get_desc - dump an SGE descriptor for debugging purposes
* @qs: the queue set
* @qnum: identifies the specific queue (0..2: Tx, 3:response, 4..5: Rx)
* @idx: the descriptor index in the queue
* @data: where to dump the descriptor contents
*
* Dumps the contents of a HW descriptor of an SGE queue. Returns the
* size of the descriptor.
*/
int t3_get_desc(const struct sge_qset *qs, unsigned int qnum, unsigned int idx,
unsigned char *data)
{
if (qnum >= 6)
return -EINVAL;
if (qnum < 3) {
if (!qs->txq[qnum].desc || idx >= qs->txq[qnum].size)
return -EINVAL;
memcpy(data, &qs->txq[qnum].desc[idx], sizeof(struct tx_desc));
return sizeof(struct tx_desc);
}
if (qnum == 3) {
if (!qs->rspq.desc || idx >= qs->rspq.size)
return -EINVAL;
memcpy(data, &qs->rspq.desc[idx], sizeof(struct rsp_desc));
return sizeof(struct rsp_desc);
}
qnum -= 4;
if (!qs->fl[qnum].desc || idx >= qs->fl[qnum].size)
return -EINVAL;
memcpy(data, &qs->fl[qnum].desc[idx], sizeof(struct rx_desc));
return sizeof(struct rx_desc);
}
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