e1000: Fix filling skb descriptors while using packet split

[linux-2.6/zen-sources.git] / drivers / net / chelsio / sge.c

/*****************************************************************************
 *                                                                           *
 * File: sge.c                                                               *
 * $Revision: 1.26 $                                                         *
 * $Date: 2005/06/21 18:29:48 $                                              *
 * Description:                                                              *
 *  DMA engine.                                                              *
 *  part of the Chelsio 10Gb Ethernet Driver.                                *
 *                                                                           *
 * This program is free software; you can redistribute it and/or modify      *
 * it under the terms of the GNU General Public License, version 2, as       *
 * published by the Free Software Foundation.                                *
 *                                                                           *
 * You should have received a copy of the GNU General Public License along   *
 * with this program; if not, write to the Free Software Foundation, Inc.,   *
 * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.                 *
 *                                                                           *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED    *
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF      *
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.                     *
 *                                                                           *
 * http://www.chelsio.com                                                    *
 *                                                                           *
 * Copyright (c) 2003 - 2005 Chelsio Communications, Inc.                    *
 * All rights reserved.                                                      *
 *                                                                           *
 * Maintainers: maintainers@chelsio.com                                      *
 *                                                                           *
 * Authors: Dimitrios Michailidis   <dm@chelsio.com>                         *
 *          Tina Yang               <tainay@chelsio.com>                     *
 *          Felix Marti             <felix@chelsio.com>                      *
 *          Scott Bardone           <sbardone@chelsio.com>                   *
 *          Kurt Ottaway            <kottaway@chelsio.com>                   *
 *          Frank DiMambro          <frank@chelsio.com>                      *
 *                                                                           *
 * History:                                                                  *
 *                                                                           *
 ****************************************************************************/

#include "common.h"

#include <linux/config.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/pci.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/if_arp.h>

#include "cpl5_cmd.h"
#include "sge.h"
#include "regs.h"
#include "espi.h"


#ifdef NETIF_F_TSO
#include <linux/tcp.h>
#endif

#define SGE_CMDQ_N              2
#define SGE_FREELQ_N            2
#define SGE_CMDQ0_E_N           1024
#define SGE_CMDQ1_E_N           128
#define SGE_FREEL_SIZE          4096
#define SGE_JUMBO_FREEL_SIZE    512
#define SGE_FREEL_REFILL_THRESH 16
#define SGE_RESPQ_E_N           1024
#define SGE_INTRTIMER_NRES      1000
#define SGE_RX_COPY_THRES       256
#define SGE_RX_SM_BUF_SIZE      1536

# define SGE_RX_DROP_THRES 2

#define SGE_RESPQ_REPLENISH_THRES (SGE_RESPQ_E_N / 4)

/*
 * 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)

#ifndef NET_IP_ALIGN
# define NET_IP_ALIGN 2
#endif

#define M_CMD_LEN       0x7fffffff
#define V_CMD_LEN(v)    (v)
#define G_CMD_LEN(v)    ((v) & M_CMD_LEN)
#define V_CMD_GEN1(v)   ((v) << 31)
#define V_CMD_GEN2(v)   (v)
#define F_CMD_DATAVALID (1 << 1)
#define F_CMD_SOP       (1 << 2)
#define V_CMD_EOP(v)    ((v) << 3)

/*
 * Command queue, receive buffer list, and response queue descriptors.
 */
#if defined(__BIG_ENDIAN_BITFIELD)
struct cmdQ_e {
        u32 addr_lo;
        u32 len_gen;
        u32 flags;
        u32 addr_hi;
};

struct freelQ_e {
        u32 addr_lo;
        u32 len_gen;
        u32 gen2;
        u32 addr_hi;
};

struct respQ_e {
        u32 Qsleeping           : 4;
        u32 Cmdq1CreditReturn   : 5;
        u32 Cmdq1DmaComplete    : 5;
        u32 Cmdq0CreditReturn   : 5;
        u32 Cmdq0DmaComplete    : 5;
        u32 FreelistQid         : 2;
        u32 CreditValid         : 1;
        u32 DataValid           : 1;
        u32 Offload             : 1;
        u32 Eop                 : 1;
        u32 Sop                 : 1;
        u32 GenerationBit       : 1;
        u32 BufferLength;
};
#elif defined(__LITTLE_ENDIAN_BITFIELD)
struct cmdQ_e {
        u32 len_gen;
        u32 addr_lo;
        u32 addr_hi;
        u32 flags;
};

struct freelQ_e {
        u32 len_gen;
        u32 addr_lo;
        u32 addr_hi;
        u32 gen2;
};

struct respQ_e {
        u32 BufferLength;
        u32 GenerationBit       : 1;
        u32 Sop                 : 1;
        u32 Eop                 : 1;
        u32 Offload             : 1;
        u32 DataValid           : 1;
        u32 CreditValid         : 1;
        u32 FreelistQid         : 2;
        u32 Cmdq0DmaComplete    : 5;
        u32 Cmdq0CreditReturn   : 5;
        u32 Cmdq1DmaComplete    : 5;
        u32 Cmdq1CreditReturn   : 5;
        u32 Qsleeping           : 4;
} ;
#endif

/*
 * SW Context Command and Freelist Queue Descriptors
 */
struct cmdQ_ce {
        struct sk_buff *skb;
        DECLARE_PCI_UNMAP_ADDR(dma_addr);
        DECLARE_PCI_UNMAP_LEN(dma_len);
};

struct freelQ_ce {
        struct sk_buff *skb;
        DECLARE_PCI_UNMAP_ADDR(dma_addr);
        DECLARE_PCI_UNMAP_LEN(dma_len);
};

/*
 * SW command, freelist and response rings
 */
struct cmdQ {
        unsigned long   status;         /* HW DMA fetch status */
        unsigned int    in_use;         /* # of in-use command descriptors */
        unsigned int    size;           /* # of descriptors */
        unsigned int    processed;      /* total # of descs HW has processed */
        unsigned int    cleaned;        /* total # of descs SW has reclaimed */
        unsigned int    stop_thres;     /* SW TX queue suspend threshold */
        u16             pidx;           /* producer index (SW) */
        u16             cidx;           /* consumer index (HW) */
        u8              genbit;         /* current generation (=valid) bit */
        u8              sop;            /* is next entry start of packet? */
        struct cmdQ_e  *entries;        /* HW command descriptor Q */
        struct cmdQ_ce *centries;       /* SW command context descriptor Q */
        spinlock_t      lock;           /* Lock to protect cmdQ enqueuing */
        dma_addr_t      dma_addr;       /* DMA addr HW command descriptor Q */
};

struct freelQ {
        unsigned int    credits;        /* # of available RX buffers */
        unsigned int    size;           /* free list capacity */
        u16             pidx;           /* producer index (SW) */
        u16             cidx;           /* consumer index (HW) */
        u16             rx_buffer_size; /* Buffer size on this free list */
        u16             dma_offset;     /* DMA offset to align IP headers */
        u16             recycleq_idx;   /* skb recycle q to use */
        u8              genbit;         /* current generation (=valid) bit */
        struct freelQ_e *entries;       /* HW freelist descriptor Q */
        struct freelQ_ce *centries;     /* SW freelist context descriptor Q */
        dma_addr_t      dma_addr;       /* DMA addr HW freelist descriptor Q */
};

struct respQ {
        unsigned int    credits;        /* credits to be returned to SGE */
        unsigned int    size;           /* # of response Q descriptors */
        u16             cidx;           /* consumer index (SW) */
        u8              genbit;         /* current generation(=valid) bit */
        struct respQ_e *entries;        /* HW response descriptor Q */
        dma_addr_t      dma_addr;       /* DMA addr HW response descriptor Q */
};

/* Bit flags for cmdQ.status */
enum {
        CMDQ_STAT_RUNNING = 1,          /* fetch engine is running */
        CMDQ_STAT_LAST_PKT_DB = 2       /* last packet rung the doorbell */
};

/*
 * Main SGE data structure
 *
 * Interrupts are handled by a single CPU and it is likely that on a MP system
 * the application is migrated to another CPU. In that scenario, we try to
 * seperate the RX(in irq context) and TX state in order to decrease memory
 * contention.
 */
struct sge {
        struct adapter *adapter;        /* adapter backpointer */
        struct net_device *netdev;      /* netdevice backpointer */
        struct freelQ   freelQ[SGE_FREELQ_N]; /* buffer free lists */
        struct respQ    respQ;          /* response Q */
        unsigned long   stopped_tx_queues; /* bitmap of suspended Tx queues */
        unsigned int    rx_pkt_pad;     /* RX padding for L2 packets */
        unsigned int    jumbo_fl;       /* jumbo freelist Q index */
        unsigned int    intrtimer_nres; /* no-resource interrupt timer */
        unsigned int    fixed_intrtimer;/* non-adaptive interrupt timer */
        struct timer_list tx_reclaim_timer; /* reclaims TX buffers */
        struct timer_list espibug_timer;
        unsigned int    espibug_timeout;
        struct sk_buff  *espibug_skb;
        u32             sge_control;    /* shadow value of sge control reg */
        struct sge_intr_counts stats;
        struct sge_port_stats port_stats[MAX_NPORTS];
        struct cmdQ cmdQ[SGE_CMDQ_N] ____cacheline_aligned_in_smp;
};

/*
 * PIO to indicate that memory mapped Q contains valid descriptor(s).
 */
static inline void doorbell_pio(struct adapter *adapter, u32 val)
{
        wmb();
        writel(val, adapter->regs + A_SG_DOORBELL);
}

/*
 * Frees all RX buffers on the freelist Q. The caller must make sure that
 * the SGE is turned off before calling this function.
 */
static void free_freelQ_buffers(struct pci_dev *pdev, struct freelQ *q)
{
        unsigned int cidx = q->cidx;

        while (q->credits--) {
                struct freelQ_ce *ce = &q->centries[cidx];

                pci_unmap_single(pdev, pci_unmap_addr(ce, dma_addr),
                                 pci_unmap_len(ce, dma_len),
                                 PCI_DMA_FROMDEVICE);
                dev_kfree_skb(ce->skb);
                ce->skb = NULL;
                if (++cidx == q->size)
                        cidx = 0;
        }
}

/*
 * Free RX free list and response queue resources.
 */
static void free_rx_resources(struct sge *sge)
{
        struct pci_dev *pdev = sge->adapter->pdev;
        unsigned int size, i;

        if (sge->respQ.entries) {
                size = sizeof(struct respQ_e) * sge->respQ.size;
                pci_free_consistent(pdev, size, sge->respQ.entries,
                                    sge->respQ.dma_addr);
        }

        for (i = 0; i < SGE_FREELQ_N; i++) {
                struct freelQ *q = &sge->freelQ[i];

                if (q->centries) {
                        free_freelQ_buffers(pdev, q);
                        kfree(q->centries);
                }
                if (q->entries) {
                        size = sizeof(struct freelQ_e) * q->size;
                        pci_free_consistent(pdev, size, q->entries,
                                            q->dma_addr);
                }
        }
}

/*
 * Allocates basic RX resources, consisting of memory mapped freelist Qs and a
 * response queue.
 */
static int alloc_rx_resources(struct sge *sge, struct sge_params *p)
{
        struct pci_dev *pdev = sge->adapter->pdev;
        unsigned int size, i;

        for (i = 0; i < SGE_FREELQ_N; i++) {
                struct freelQ *q = &sge->freelQ[i];

                q->genbit = 1;
                q->size = p->freelQ_size[i];
                q->dma_offset = sge->rx_pkt_pad ? 0 : NET_IP_ALIGN;
                size = sizeof(struct freelQ_e) * q->size;
                q->entries = (struct freelQ_e *)
                              pci_alloc_consistent(pdev, size, &q->dma_addr);
                if (!q->entries)
                        goto err_no_mem;
                memset(q->entries, 0, size);
                size = sizeof(struct freelQ_ce) * q->size;
                q->centries = kmalloc(size, GFP_KERNEL);
                if (!q->centries)
                        goto err_no_mem;
                memset(q->centries, 0, size);
        }

        /*
         * Calculate the buffer sizes for the two free lists.  FL0 accommodates
         * regular sized Ethernet frames, FL1 is sized not to exceed 16K,
         * including all the sk_buff overhead.
         *
         * Note: For T2 FL0 and FL1 are reversed.
         */
        sge->freelQ[!sge->jumbo_fl].rx_buffer_size = SGE_RX_SM_BUF_SIZE +
                sizeof(struct cpl_rx_data) +
                sge->freelQ[!sge->jumbo_fl].dma_offset;
        sge->freelQ[sge->jumbo_fl].rx_buffer_size = (16 * 1024) -
                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        /*
         * Setup which skb recycle Q should be used when recycling buffers from
         * each free list.
         */
        sge->freelQ[!sge->jumbo_fl].recycleq_idx = 0;
        sge->freelQ[sge->jumbo_fl].recycleq_idx = 1;

        sge->respQ.genbit = 1;
        sge->respQ.size = SGE_RESPQ_E_N;
        sge->respQ.credits = 0;
        size = sizeof(struct respQ_e) * sge->respQ.size;
        sge->respQ.entries = (struct respQ_e *)
                pci_alloc_consistent(pdev, size, &sge->respQ.dma_addr);
        if (!sge->respQ.entries)
                goto err_no_mem;
        memset(sge->respQ.entries, 0, size);
        return 0;

err_no_mem:
        free_rx_resources(sge);
        return -ENOMEM;
}

/*
 * Reclaims n TX descriptors and frees the buffers associated with them.
 */
static void free_cmdQ_buffers(struct sge *sge, struct cmdQ *q, unsigned int n)
{
        struct cmdQ_ce *ce;
        struct pci_dev *pdev = sge->adapter->pdev;
        unsigned int cidx = q->cidx;

        q->in_use -= n;
        ce = &q->centries[cidx];
        while (n--) {
                if (q->sop)
                        pci_unmap_single(pdev, pci_unmap_addr(ce, dma_addr),
                                         pci_unmap_len(ce, dma_len),
                                         PCI_DMA_TODEVICE);
                else
                        pci_unmap_page(pdev, pci_unmap_addr(ce, dma_addr),
                                       pci_unmap_len(ce, dma_len),
                                       PCI_DMA_TODEVICE);
                q->sop = 0;
                if (ce->skb) {
                        dev_kfree_skb(ce->skb);
                        q->sop = 1;
                }
                ce++;
                if (++cidx == q->size) {
                        cidx = 0;
                        ce = q->centries;
                }
        }
        q->cidx = cidx;
}

/*
 * Free TX resources.
 *
 * Assumes that SGE is stopped and all interrupts are disabled.
 */
static void free_tx_resources(struct sge *sge)
{
        struct pci_dev *pdev = sge->adapter->pdev;
        unsigned int size, i;

        for (i = 0; i < SGE_CMDQ_N; i++) {
                struct cmdQ *q = &sge->cmdQ[i];

                if (q->centries) {
                        if (q->in_use)
                                free_cmdQ_buffers(sge, q, q->in_use);
                        kfree(q->centries);
                }
                if (q->entries) {
                        size = sizeof(struct cmdQ_e) * q->size;
                        pci_free_consistent(pdev, size, q->entries,
                                            q->dma_addr);
                }
        }
}

/*
 * Allocates basic TX resources, consisting of memory mapped command Qs.
 */
static int alloc_tx_resources(struct sge *sge, struct sge_params *p)
{
        struct pci_dev *pdev = sge->adapter->pdev;
        unsigned int size, i;

        for (i = 0; i < SGE_CMDQ_N; i++) {
                struct cmdQ *q = &sge->cmdQ[i];

                q->genbit = 1;
                q->sop = 1;
                q->size = p->cmdQ_size[i];
                q->in_use = 0;
                q->status = 0;
                q->processed = q->cleaned = 0;
                q->stop_thres = 0;
                spin_lock_init(&q->lock);
                size = sizeof(struct cmdQ_e) * q->size;
                q->entries = (struct cmdQ_e *)
                              pci_alloc_consistent(pdev, size, &q->dma_addr);
                if (!q->entries)
                        goto err_no_mem;
                memset(q->entries, 0, size);
                size = sizeof(struct cmdQ_ce) * q->size;
                q->centries = kmalloc(size, GFP_KERNEL);
                if (!q->centries)
                        goto err_no_mem;
                memset(q->centries, 0, size);
        }

        /*
         * CommandQ 0 handles Ethernet and TOE packets, while queue 1 is TOE
         * only.  For queue 0 set the stop threshold so we can handle one more
         * packet from each port, plus reserve an additional 24 entries for
         * Ethernet packets only.  Queue 1 never suspends nor do we reserve
         * space for Ethernet packets.
         */
        sge->cmdQ[0].stop_thres = sge->adapter->params.nports *
                (MAX_SKB_FRAGS + 1);
        return 0;

err_no_mem:
        free_tx_resources(sge);
        return -ENOMEM;
}

static inline void setup_ring_params(struct adapter *adapter, u64 addr,
                                     u32 size, int base_reg_lo,
                                     int base_reg_hi, int size_reg)
{
        writel((u32)addr, adapter->regs + base_reg_lo);
        writel(addr >> 32, adapter->regs + base_reg_hi);
        writel(size, adapter->regs + size_reg);
}

/*
 * Enable/disable VLAN acceleration.
 */
void t1_set_vlan_accel(struct adapter *adapter, int on_off)
{
        struct sge *sge = adapter->sge;

        sge->sge_control &= ~F_VLAN_XTRACT;
        if (on_off)
                sge->sge_control |= F_VLAN_XTRACT;
        if (adapter->open_device_map) {
                writel(sge->sge_control, adapter->regs + A_SG_CONTROL);
                readl(adapter->regs + A_SG_CONTROL); /* flush */
        }
}

/*
 * Programs the various SGE registers. However, the engine is not yet enabled,
 * but sge->sge_control is setup and ready to go.
 */
static void configure_sge(struct sge *sge, struct sge_params *p)
{
        struct adapter *ap = sge->adapter;
        
        writel(0, ap->regs + A_SG_CONTROL);
        setup_ring_params(ap, sge->cmdQ[0].dma_addr, sge->cmdQ[0].size,
                          A_SG_CMD0BASELWR, A_SG_CMD0BASEUPR, A_SG_CMD0SIZE);
        setup_ring_params(ap, sge->cmdQ[1].dma_addr, sge->cmdQ[1].size,
                          A_SG_CMD1BASELWR, A_SG_CMD1BASEUPR, A_SG_CMD1SIZE);
        setup_ring_params(ap, sge->freelQ[0].dma_addr,
                          sge->freelQ[0].size, A_SG_FL0BASELWR,
                          A_SG_FL0BASEUPR, A_SG_FL0SIZE);
        setup_ring_params(ap, sge->freelQ[1].dma_addr,
                          sge->freelQ[1].size, A_SG_FL1BASELWR,
                          A_SG_FL1BASEUPR, A_SG_FL1SIZE);

        /* The threshold comparison uses <. */
        writel(SGE_RX_SM_BUF_SIZE + 1, ap->regs + A_SG_FLTHRESHOLD);

        setup_ring_params(ap, sge->respQ.dma_addr, sge->respQ.size,
                          A_SG_RSPBASELWR, A_SG_RSPBASEUPR, A_SG_RSPSIZE);
        writel((u32)sge->respQ.size - 1, ap->regs + A_SG_RSPQUEUECREDIT);

        sge->sge_control = F_CMDQ0_ENABLE | F_CMDQ1_ENABLE | F_FL0_ENABLE |
                F_FL1_ENABLE | F_CPL_ENABLE | F_RESPONSE_QUEUE_ENABLE |
                V_CMDQ_PRIORITY(2) | F_DISABLE_CMDQ1_GTS | F_ISCSI_COALESCE |
                F_DISABLE_FL0_GTS | F_DISABLE_FL1_GTS |
                V_RX_PKT_OFFSET(sge->rx_pkt_pad);

#if defined(__BIG_ENDIAN_BITFIELD)
        sge->sge_control |= F_ENABLE_BIG_ENDIAN;
#endif

        /* Initialize no-resource timer */
        sge->intrtimer_nres = SGE_INTRTIMER_NRES * core_ticks_per_usec(ap);

        t1_sge_set_coalesce_params(sge, p);
}

/*
 * Return the payload capacity of the jumbo free-list buffers.
 */
static inline unsigned int jumbo_payload_capacity(const struct sge *sge)
{
        return sge->freelQ[sge->jumbo_fl].rx_buffer_size -
                sge->freelQ[sge->jumbo_fl].dma_offset -
                sizeof(struct cpl_rx_data);
}

/*
 * Frees all SGE related resources and the sge structure itself
 */
void t1_sge_destroy(struct sge *sge)
{
        if (sge->espibug_skb)
                kfree_skb(sge->espibug_skb);

        free_tx_resources(sge);
        free_rx_resources(sge);
        kfree(sge);
}

/*
 * Allocates new RX buffers on the freelist Q (and tracks them on the freelist
 * context Q) until the Q is full or alloc_skb fails.
 *
 * It is possible that the generation bits already match, indicating that the
 * buffer is already valid and nothing needs to be done. This happens when we
 * copied a received buffer into a new sk_buff during the interrupt processing.
 *
 * If the SGE doesn't automatically align packets properly (!sge->rx_pkt_pad),
 * we specify a RX_OFFSET in order to make sure that the IP header is 4B
 * aligned.
 */
static void refill_free_list(struct sge *sge, struct freelQ *q)
{
        struct pci_dev *pdev = sge->adapter->pdev;
        struct freelQ_ce *ce = &q->centries[q->pidx];
        struct freelQ_e *e = &q->entries[q->pidx];
        unsigned int dma_len = q->rx_buffer_size - q->dma_offset;


        while (q->credits < q->size) {
                struct sk_buff *skb;
                dma_addr_t mapping;

                skb = alloc_skb(q->rx_buffer_size, GFP_ATOMIC);
                if (!skb)
                        break;

                skb_reserve(skb, q->dma_offset);
                mapping = pci_map_single(pdev, skb->data, dma_len,
                                         PCI_DMA_FROMDEVICE);
                ce->skb = skb;
                pci_unmap_addr_set(ce, dma_addr, mapping);
                pci_unmap_len_set(ce, dma_len, dma_len);
                e->addr_lo = (u32)mapping;
                e->addr_hi = (u64)mapping >> 32;
                e->len_gen = V_CMD_LEN(dma_len) | V_CMD_GEN1(q->genbit);
                wmb();
                e->gen2 = V_CMD_GEN2(q->genbit);

                e++;
                ce++;
                if (++q->pidx == q->size) {
                        q->pidx = 0;
                        q->genbit ^= 1;
                        ce = q->centries;
                        e = q->entries;
                }
                q->credits++;
        }

}

/*
 * Calls refill_free_list for both free lists. If we cannot fill at least 1/4
 * of both rings, we go into 'few interrupt mode' in order to give the system
 * time to free up resources.
 */
static void freelQs_empty(struct sge *sge)
{
        struct adapter *adapter = sge->adapter;
        u32 irq_reg = readl(adapter->regs + A_SG_INT_ENABLE);
        u32 irqholdoff_reg;

        refill_free_list(sge, &sge->freelQ[0]);
        refill_free_list(sge, &sge->freelQ[1]);

        if (sge->freelQ[0].credits > (sge->freelQ[0].size >> 2) &&
            sge->freelQ[1].credits > (sge->freelQ[1].size >> 2)) {
                irq_reg |= F_FL_EXHAUSTED;
                irqholdoff_reg = sge->fixed_intrtimer;
        } else {
                /* Clear the F_FL_EXHAUSTED interrupts for now */
                irq_reg &= ~F_FL_EXHAUSTED;
                irqholdoff_reg = sge->intrtimer_nres;
        }
        writel(irqholdoff_reg, adapter->regs + A_SG_INTRTIMER);
        writel(irq_reg, adapter->regs + A_SG_INT_ENABLE);

        /* We reenable the Qs to force a freelist GTS interrupt later */
        doorbell_pio(adapter, F_FL0_ENABLE | F_FL1_ENABLE);
}

#define SGE_PL_INTR_MASK (F_PL_INTR_SGE_ERR | F_PL_INTR_SGE_DATA)
#define SGE_INT_FATAL (F_RESPQ_OVERFLOW | F_PACKET_TOO_BIG | F_PACKET_MISMATCH)
#define SGE_INT_ENABLE (F_RESPQ_EXHAUSTED | F_RESPQ_OVERFLOW | \
                        F_FL_EXHAUSTED | F_PACKET_TOO_BIG | F_PACKET_MISMATCH)

/*
 * Disable SGE Interrupts
 */
void t1_sge_intr_disable(struct sge *sge)
{
        u32 val = readl(sge->adapter->regs + A_PL_ENABLE);

        writel(val & ~SGE_PL_INTR_MASK, sge->adapter->regs + A_PL_ENABLE);
        writel(0, sge->adapter->regs + A_SG_INT_ENABLE);
}

/*
 * Enable SGE interrupts.
 */
void t1_sge_intr_enable(struct sge *sge)
{
        u32 en = SGE_INT_ENABLE;
        u32 val = readl(sge->adapter->regs + A_PL_ENABLE);

        if (sge->adapter->flags & TSO_CAPABLE)
                en &= ~F_PACKET_TOO_BIG;
        writel(en, sge->adapter->regs + A_SG_INT_ENABLE);
        writel(val | SGE_PL_INTR_MASK, sge->adapter->regs + A_PL_ENABLE);
}

/*
 * Clear SGE interrupts.
 */
void t1_sge_intr_clear(struct sge *sge)
{
        writel(SGE_PL_INTR_MASK, sge->adapter->regs + A_PL_CAUSE);
        writel(0xffffffff, sge->adapter->regs + A_SG_INT_CAUSE);
}

/*
 * SGE 'Error' interrupt handler
 */
int t1_sge_intr_error_handler(struct sge *sge)
{
        struct adapter *adapter = sge->adapter;
        u32 cause = readl(adapter->regs + A_SG_INT_CAUSE);

        if (adapter->flags & TSO_CAPABLE)
                cause &= ~F_PACKET_TOO_BIG;
        if (cause & F_RESPQ_EXHAUSTED)
                sge->stats.respQ_empty++;
        if (cause & F_RESPQ_OVERFLOW) {
                sge->stats.respQ_overflow++;
                CH_ALERT("%s: SGE response queue overflow\n",
                         adapter->name);
        }
        if (cause & F_FL_EXHAUSTED) {
                sge->stats.freelistQ_empty++;
                freelQs_empty(sge);
        }
        if (cause & F_PACKET_TOO_BIG) {
                sge->stats.pkt_too_big++;
                CH_ALERT("%s: SGE max packet size exceeded\n",
                         adapter->name);
        }
        if (cause & F_PACKET_MISMATCH) {
                sge->stats.pkt_mismatch++;
                CH_ALERT("%s: SGE packet mismatch\n", adapter->name);
        }
        if (cause & SGE_INT_FATAL)
                t1_fatal_err(adapter);

        writel(cause, adapter->regs + A_SG_INT_CAUSE);
        return 0;
}

const struct sge_intr_counts *t1_sge_get_intr_counts(struct sge *sge)
{
        return &sge->stats;
}

const struct sge_port_stats *t1_sge_get_port_stats(struct sge *sge, int port)
{
        return &sge->port_stats[port];
}

/**
 *      recycle_fl_buf - recycle a free list buffer
 *      @fl: the 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_fl_buf(struct freelQ *fl, int idx)
{
        struct freelQ_e *from = &fl->entries[idx];
        struct freelQ_e *to = &fl->entries[fl->pidx];

        fl->centries[fl->pidx] = fl->centries[idx];
        to->addr_lo = from->addr_lo;
        to->addr_hi = from->addr_hi;
        to->len_gen = G_CMD_LEN(from->len_gen) | V_CMD_GEN1(fl->genbit);
        wmb();
        to->gen2 = V_CMD_GEN2(fl->genbit);
        fl->credits++;

        if (++fl->pidx == fl->size) {
                fl->pidx = 0;
                fl->genbit ^= 1;
        }
}

/**
 *      get_packet - return the next ingress packet buffer
 *      @pdev: the PCI device that received the packet
 *      @fl: the SGE free list holding the packet
 *      @len: the actual packet length, excluding any SGE padding
 *      @dma_pad: padding at beginning of buffer left by SGE DMA
 *      @skb_pad: padding to be used if the packet is copied
 *      @copy_thres: length threshold under which a packet should be copied
 *      @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 inline struct sk_buff *get_packet(struct pci_dev *pdev,
                                         struct freelQ *fl, unsigned int len,
                                         int dma_pad, int skb_pad,
                                         unsigned int copy_thres,
                                         unsigned int drop_thres)
{
        struct sk_buff *skb;
        struct freelQ_ce *ce = &fl->centries[fl->cidx];

        if (len < copy_thres) {
                skb = alloc_skb(len + skb_pad, GFP_ATOMIC);
                if (likely(skb != NULL)) {
                        skb_reserve(skb, skb_pad);
                        skb_put(skb, len);
                        pci_dma_sync_single_for_cpu(pdev,
                                            pci_unmap_addr(ce, dma_addr),
                                            pci_unmap_len(ce, dma_len),
                                            PCI_DMA_FROMDEVICE);
                        memcpy(skb->data, ce->skb->data + dma_pad, len);
                        pci_dma_sync_single_for_device(pdev,
                                            pci_unmap_addr(ce, dma_addr),
                                            pci_unmap_len(ce, dma_len),
                                            PCI_DMA_FROMDEVICE);
                } else if (!drop_thres)
                        goto use_orig_buf;

                recycle_fl_buf(fl, fl->cidx);
                return skb;
        }

        if (fl->credits < drop_thres) {
                recycle_fl_buf(fl, fl->cidx);
                return NULL;
        }

use_orig_buf:
        pci_unmap_single(pdev, pci_unmap_addr(ce, dma_addr),
                         pci_unmap_len(ce, dma_len), PCI_DMA_FROMDEVICE);
        skb = ce->skb;
        skb_reserve(skb, dma_pad);
        skb_put(skb, len);
        return skb;
}

/**
 *      unexpected_offload - handle an unexpected offload packet
 *      @adapter: the adapter
 *      @fl: the free list that received the packet
 *
 *      Called when we receive an unexpected offload packet (e.g., the TOE
 *      function is disabled or the card is a NIC).  Prints a message and
 *      recycles the buffer.
 */
static void unexpected_offload(struct adapter *adapter, struct freelQ *fl)
{
        struct freelQ_ce *ce = &fl->centries[fl->cidx];
        struct sk_buff *skb = ce->skb;

        pci_dma_sync_single_for_cpu(adapter->pdev, pci_unmap_addr(ce, dma_addr),
                            pci_unmap_len(ce, dma_len), PCI_DMA_FROMDEVICE);
        CH_ERR("%s: unexpected offload packet, cmd %u\n",
               adapter->name, *skb->data);
        recycle_fl_buf(fl, fl->cidx);
}

/*
 * Write the command descriptors to transmit the given skb starting at
 * descriptor pidx with the given generation.
 */
static inline void write_tx_descs(struct adapter *adapter, struct sk_buff *skb,
                                  unsigned int pidx, unsigned int gen,
                                  struct cmdQ *q)
{
        dma_addr_t mapping;
        struct cmdQ_e *e, *e1;
        struct cmdQ_ce *ce;
        unsigned int i, flags, nfrags = skb_shinfo(skb)->nr_frags;

        mapping = pci_map_single(adapter->pdev, skb->data,
                                 skb->len - skb->data_len, PCI_DMA_TODEVICE);
        ce = &q->centries[pidx];
        ce->skb = NULL;
        pci_unmap_addr_set(ce, dma_addr, mapping);
        pci_unmap_len_set(ce, dma_len, skb->len - skb->data_len);

        flags = F_CMD_DATAVALID | F_CMD_SOP | V_CMD_EOP(nfrags == 0) |
                V_CMD_GEN2(gen);
        e = &q->entries[pidx];
        e->addr_lo = (u32)mapping;
        e->addr_hi = (u64)mapping >> 32;
        e->len_gen = V_CMD_LEN(skb->len - skb->data_len) | V_CMD_GEN1(gen);
        for (e1 = e, i = 0; nfrags--; i++) {
                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                ce++;
                e1++;
                if (++pidx == q->size) {
                        pidx = 0;
                        gen ^= 1;
                        ce = q->centries;
                        e1 = q->entries;
                }

                mapping = pci_map_page(adapter->pdev, frag->page,
                                       frag->page_offset, frag->size,
                                       PCI_DMA_TODEVICE);
                ce->skb = NULL;
                pci_unmap_addr_set(ce, dma_addr, mapping);
                pci_unmap_len_set(ce, dma_len, frag->size);

                e1->addr_lo = (u32)mapping;
                e1->addr_hi = (u64)mapping >> 32;
                e1->len_gen = V_CMD_LEN(frag->size) | V_CMD_GEN1(gen);
                e1->flags = F_CMD_DATAVALID | V_CMD_EOP(nfrags == 0) |
                            V_CMD_GEN2(gen);
        }

        ce->skb = skb;
        wmb();
        e->flags = flags;
}

/*
 * Clean up completed Tx buffers.
 */
static inline void reclaim_completed_tx(struct sge *sge, struct cmdQ *q)
{
        unsigned int reclaim = q->processed - q->cleaned;

        if (reclaim) {
                free_cmdQ_buffers(sge, q, reclaim);
                q->cleaned += reclaim;
        }
}

#ifndef SET_ETHTOOL_OPS
# define __netif_rx_complete(dev) netif_rx_complete(dev)
#endif

/*
 * We cannot use the standard netif_rx_schedule_prep() because we have multiple
 * ports plus the TOE all multiplexing onto a single response queue, therefore
 * accepting new responses cannot depend on the state of any particular port.
 * So define our own equivalent that omits the netif_running() test.
 */
static inline int napi_schedule_prep(struct net_device *dev)
{
        return !test_and_set_bit(__LINK_STATE_RX_SCHED, &dev->state);
}


/**
 *      sge_rx - process an ingress ethernet packet
 *      @sge: the sge structure
 *      @fl: the free list that contains the packet buffer
 *      @len: the packet length
 *
 *      Process an ingress ethernet pakcet and deliver it to the stack.
 */
static int sge_rx(struct sge *sge, struct freelQ *fl, unsigned int len)
{
        struct sk_buff *skb;
        struct cpl_rx_pkt *p;
        struct adapter *adapter = sge->adapter;

        sge->stats.ethernet_pkts++;
        skb = get_packet(adapter->pdev, fl, len - sge->rx_pkt_pad,
                         sge->rx_pkt_pad, 2, SGE_RX_COPY_THRES,
                         SGE_RX_DROP_THRES);
        if (!skb) {
                sge->port_stats[0].rx_drops++; /* charge only port 0 for now */
                return 0;
        }

        p = (struct cpl_rx_pkt *)skb->data;
        skb_pull(skb, sizeof(*p));
        skb->dev = adapter->port[p->iff].dev;
        skb->dev->last_rx = jiffies;
        skb->protocol = eth_type_trans(skb, skb->dev);
        if ((adapter->flags & RX_CSUM_ENABLED) && p->csum == 0xffff &&
            skb->protocol == htons(ETH_P_IP) &&
            (skb->data[9] == IPPROTO_TCP || skb->data[9] == IPPROTO_UDP)) {
                sge->port_stats[p->iff].rx_cso_good++;
                skb->ip_summed = CHECKSUM_UNNECESSARY;
        } else
                skb->ip_summed = CHECKSUM_NONE;

        if (unlikely(adapter->vlan_grp && p->vlan_valid)) {
                sge->port_stats[p->iff].vlan_xtract++;
                if (adapter->params.sge.polling)
                        vlan_hwaccel_receive_skb(skb, adapter->vlan_grp,
                                                 ntohs(p->vlan));
                else
                        vlan_hwaccel_rx(skb, adapter->vlan_grp,
                                        ntohs(p->vlan));
        } else if (adapter->params.sge.polling)
                netif_receive_skb(skb);
        else
                netif_rx(skb);
        return 0;
}

/*
 * Returns true if a command queue has enough available descriptors that
 * we can resume Tx operation after temporarily disabling its packet queue.
 */
static inline int enough_free_Tx_descs(const struct cmdQ *q)
{
        unsigned int r = q->processed - q->cleaned;

        return q->in_use - r < (q->size >> 1);
}

/*
 * Called when sufficient space has become available in the SGE command queues
 * after the Tx packet schedulers have been suspended to restart the Tx path.
 */
static void restart_tx_queues(struct sge *sge)
{
        struct adapter *adap = sge->adapter;

        if (enough_free_Tx_descs(&sge->cmdQ[0])) {
                int i;

                for_each_port(adap, i) {
                        struct net_device *nd = adap->port[i].dev;

                        if (test_and_clear_bit(nd->if_port,
                                               &sge->stopped_tx_queues) &&
                            netif_running(nd)) {
                                sge->stats.cmdQ_restarted[3]++;
                                netif_wake_queue(nd);
                        }
                }
        }
}

/*
 * update_tx_info is called from the interrupt handler/NAPI to return cmdQ0 
 * information.
 */
static unsigned int update_tx_info(struct adapter *adapter, 
                                          unsigned int flags, 
                                          unsigned int pr0)
{
        struct sge *sge = adapter->sge;
        struct cmdQ *cmdq = &sge->cmdQ[0];

        cmdq->processed += pr0;

        if (flags & F_CMDQ0_ENABLE) {
                clear_bit(CMDQ_STAT_RUNNING, &cmdq->status);
        
                if (cmdq->cleaned + cmdq->in_use != cmdq->processed &&
                    !test_and_set_bit(CMDQ_STAT_LAST_PKT_DB, &cmdq->status)) {
                        set_bit(CMDQ_STAT_RUNNING, &cmdq->status);
                        writel(F_CMDQ0_ENABLE, adapter->regs + A_SG_DOORBELL);
                }
                flags &= ~F_CMDQ0_ENABLE;
        }
        
        if (unlikely(sge->stopped_tx_queues != 0))
                restart_tx_queues(sge);

        return flags;
}

/*
 * Process SGE responses, up to the supplied budget.  Returns the number of
 * responses processed.  A negative budget is effectively unlimited.
 */
static int process_responses(struct adapter *adapter, int budget)
{
        struct sge *sge = adapter->sge;
        struct respQ *q = &sge->respQ;
        struct respQ_e *e = &q->entries[q->cidx];
        int budget_left = budget;
        unsigned int flags = 0;
        unsigned int cmdq_processed[SGE_CMDQ_N] = {0, 0};
        

        while (likely(budget_left && e->GenerationBit == q->genbit)) {
                flags |= e->Qsleeping;
                
                cmdq_processed[0] += e->Cmdq0CreditReturn;
                cmdq_processed[1] += e->Cmdq1CreditReturn;
                
                /* We batch updates to the TX side to avoid cacheline
                 * ping-pong of TX state information on MP where the sender
                 * might run on a different CPU than this function...
                 */
                if (unlikely(flags & F_CMDQ0_ENABLE || cmdq_processed[0] > 64)) {
                        flags = update_tx_info(adapter, flags, cmdq_processed[0]);
                        cmdq_processed[0] = 0;
                }
                if (unlikely(cmdq_processed[1] > 16)) {
                        sge->cmdQ[1].processed += cmdq_processed[1];
                        cmdq_processed[1] = 0;
                }
                if (likely(e->DataValid)) {
                        struct freelQ *fl = &sge->freelQ[e->FreelistQid];

                        if (unlikely(!e->Sop || !e->Eop))
                                BUG();
                        if (unlikely(e->Offload))
                                unexpected_offload(adapter, fl);
                        else
                                sge_rx(sge, fl, e->BufferLength);

                        /*
                         * Note: this depends on each packet consuming a
                         * single free-list buffer; cf. the BUG above.
                         */
                        if (++fl->cidx == fl->size)
                                fl->cidx = 0;
                        if (unlikely(--fl->credits <
                                     fl->size - SGE_FREEL_REFILL_THRESH))
                                refill_free_list(sge, fl);
                } else
                        sge->stats.pure_rsps++;

                e++;
                if (unlikely(++q->cidx == q->size)) {
                        q->cidx = 0;
                        q->genbit ^= 1;
                        e = q->entries;
                }
                prefetch(e);

                if (++q->credits > SGE_RESPQ_REPLENISH_THRES) {
                        writel(q->credits, adapter->regs + A_SG_RSPQUEUECREDIT);
                        q->credits = 0;
                }
                --budget_left;
        }

        flags = update_tx_info(adapter, flags, cmdq_processed[0]); 
        sge->cmdQ[1].processed += cmdq_processed[1];

        budget -= budget_left;
        return budget;
}

/*
 * 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 when using NAPI, so we handle them specially in hard
 * interrupt context.  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 *adapter, struct respQ_e *e)
{
        struct sge *sge = adapter->sge;
        struct respQ *q = &sge->respQ;
        unsigned int flags = 0;
        unsigned int cmdq_processed[SGE_CMDQ_N] = {0, 0};

        do {
                flags |= e->Qsleeping;

                cmdq_processed[0] += e->Cmdq0CreditReturn;
                cmdq_processed[1] += e->Cmdq1CreditReturn;
                
                e++;
                if (unlikely(++q->cidx == q->size)) {
                        q->cidx = 0;
                        q->genbit ^= 1;
                        e = q->entries;
                }
                prefetch(e);

                if (++q->credits > SGE_RESPQ_REPLENISH_THRES) {
                        writel(q->credits, adapter->regs + A_SG_RSPQUEUECREDIT);
                        q->credits = 0;
                }
                sge->stats.pure_rsps++;
        } while (e->GenerationBit == q->genbit && !e->DataValid);

        flags = update_tx_info(adapter, flags, cmdq_processed[0]); 
        sge->cmdQ[1].processed += cmdq_processed[1];

        return e->GenerationBit == q->genbit;
}

/*
 * Handler for new data events when using NAPI.  This does not need any locking
 * or protection from interrupts as data interrupts are off at this point and
 * other adapter interrupts do not interfere.
 */
static int t1_poll(struct net_device *dev, int *budget)
{
        struct adapter *adapter = dev->priv;
        int effective_budget = min(*budget, dev->quota);

        int work_done = process_responses(adapter, 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.
         */
        writel(adapter->sge->respQ.cidx, adapter->regs + A_SG_SLEEPING);
        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);
}

/*
 * NAPI version of the main interrupt handler.
 */
static irqreturn_t t1_interrupt_napi(int irq, void *data, struct pt_regs *regs)
{
        int handled;
        struct adapter *adapter = data;
        struct sge *sge = adapter->sge;
        struct respQ *q = &adapter->sge->respQ;

        /*
         * Clear the SGE_DATA interrupt first thing.  Normally the NAPI
         * handler has control of the response queue and the interrupt handler
         * can look at the queue reliably only once it knows NAPI is off.
         * We can't wait that long to clear the SGE_DATA interrupt because we
         * could race with t1_poll rearming the SGE interrupt, so we need to
         * clear the interrupt speculatively and really early on.
         */
        writel(F_PL_INTR_SGE_DATA, adapter->regs + A_PL_CAUSE);

        spin_lock(&adapter->async_lock);
        if (!napi_is_scheduled(sge->netdev)) {
                struct respQ_e *e = &q->entries[q->cidx];

                if (e->GenerationBit == q->genbit) {
                        if (e->DataValid ||
                            process_pure_responses(adapter, e)) {
                                if (likely(napi_schedule_prep(sge->netdev)))
                                        __netif_rx_schedule(sge->netdev);
                                else
                                        printk(KERN_CRIT
                                               "NAPI schedule failure!\n");
                        } else
                        writel(q->cidx, adapter->regs + A_SG_SLEEPING);
                        handled = 1;
                        goto unlock;
                } else
                writel(q->cidx, adapter->regs + A_SG_SLEEPING);
        }  else
        if (readl(adapter->regs + A_PL_CAUSE) & F_PL_INTR_SGE_DATA)
                printk(KERN_ERR "data interrupt while NAPI running\n");
        
        handled = t1_slow_intr_handler(adapter);
        if (!handled)
                sge->stats.unhandled_irqs++;
 unlock:
        spin_unlock(&adapter->async_lock);
        return IRQ_RETVAL(handled != 0);
}

/*
 * Main interrupt handler, optimized assuming that we took a 'DATA'
 * interrupt.
 *
 * 1. Clear the interrupt
 * 2. Loop while we find valid descriptors and process them; accumulate
 *      information that can be processed after the loop
 * 3. Tell the SGE at which index we stopped processing descriptors
 * 4. Bookkeeping; free TX buffers, ring doorbell if there are any
 *      outstanding TX buffers waiting, replenish RX buffers, potentially
 *      reenable upper layers if they were turned off due to lack of TX
 *      resources which are available again.
 * 5. If we took an interrupt, but no valid respQ descriptors was found we
 *      let the slow_intr_handler run and do error handling.
 */
static irqreturn_t t1_interrupt(int irq, void *cookie, struct pt_regs *regs)
{
        int work_done;
        struct respQ_e *e;
        struct adapter *adapter = cookie;
        struct respQ *Q = &adapter->sge->respQ;

        spin_lock(&adapter->async_lock);
        e = &Q->entries[Q->cidx];
        prefetch(e);

        writel(F_PL_INTR_SGE_DATA, adapter->regs + A_PL_CAUSE);

        if (likely(e->GenerationBit == Q->genbit))
                work_done = process_responses(adapter, -1);
        else
                work_done = t1_slow_intr_handler(adapter);

        /*
         * The unconditional clearing of the PL_CAUSE above may have raced
         * with DMA completion and the corresponding generation of a response
         * to cause us to miss the resulting data interrupt.  The next write
         * is also unconditional to recover the missed interrupt and render
         * this race harmless.
         */
        writel(Q->cidx, adapter->regs + A_SG_SLEEPING);

        if (!work_done)
                adapter->sge->stats.unhandled_irqs++;
        spin_unlock(&adapter->async_lock);
        return IRQ_RETVAL(work_done != 0);
}

intr_handler_t t1_select_intr_handler(adapter_t *adapter)
{
        return adapter->params.sge.polling ? t1_interrupt_napi : t1_interrupt;
}

/*
 * Enqueues the sk_buff onto the cmdQ[qid] and has hardware fetch it.
 *
 * The code figures out how many entries the sk_buff will require in the
 * cmdQ and updates the cmdQ data structure with the state once the enqueue
 * has complete. Then, it doesn't access the global structure anymore, but
 * uses the corresponding fields on the stack. In conjuction with a spinlock
 * around that code, we can make the function reentrant without holding the
 * lock when we actually enqueue (which might be expensive, especially on
 * architectures with IO MMUs).
 *
 * This runs with softirqs disabled.
 */
static int t1_sge_tx(struct sk_buff *skb, struct adapter *adapter,
                     unsigned int qid, struct net_device *dev)
{
        struct sge *sge = adapter->sge;
        struct cmdQ *q = &sge->cmdQ[qid];
        unsigned int credits, pidx, genbit, count;

        spin_lock(&q->lock);
        reclaim_completed_tx(sge, q);

        pidx = q->pidx;
        credits = q->size - q->in_use;
        count = 1 + skb_shinfo(skb)->nr_frags;

        {       /* Ethernet packet */
                if (unlikely(credits < count)) {
                        netif_stop_queue(dev);
                        set_bit(dev->if_port, &sge->stopped_tx_queues);
                        sge->stats.cmdQ_full[3]++;
                        spin_unlock(&q->lock);
                        if (!netif_queue_stopped(dev))
                                CH_ERR("%s: Tx ring full while queue awake!\n",
                                       adapter->name);
                        return NETDEV_TX_BUSY;
                }
                if (unlikely(credits - count < q->stop_thres)) {
                        sge->stats.cmdQ_full[3]++;
                        netif_stop_queue(dev);
                        set_bit(dev->if_port, &sge->stopped_tx_queues);
                }
        }
        q->in_use += count;
        genbit = q->genbit;
        q->pidx += count;
        if (q->pidx >= q->size) {
                q->pidx -= q->size;
                q->genbit ^= 1;
        }
        spin_unlock(&q->lock);

        write_tx_descs(adapter, skb, pidx, genbit, q);

        /*
         * We always ring the doorbell for cmdQ1.  For cmdQ0, we only ring
         * the doorbell if the Q is asleep. There is a natural race, where
         * the hardware 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.
         */
        if (qid)
                doorbell_pio(adapter, F_CMDQ1_ENABLE);
        else {
                clear_bit(CMDQ_STAT_LAST_PKT_DB, &q->status);
                if (test_and_set_bit(CMDQ_STAT_RUNNING, &q->status) == 0) {
                        set_bit(CMDQ_STAT_LAST_PKT_DB, &q->status);
                        writel(F_CMDQ0_ENABLE, adapter->regs + A_SG_DOORBELL);
                }
        }
        return NETDEV_TX_OK;
}

#define MK_ETH_TYPE_MSS(type, mss) (((mss) & 0x3FFF) | ((type) << 14))

/*
 *      eth_hdr_len - return the length of an Ethernet header
 *      @data: pointer to the start of the Ethernet header
 *
 *      Returns the length of an Ethernet header, including optional VLAN tag.
 */
static inline int eth_hdr_len(const void *data)
{
        const struct ethhdr *e = data;

        return e->h_proto == htons(ETH_P_8021Q) ? VLAN_ETH_HLEN : ETH_HLEN;
}

/*
 * Adds the CPL header to the sk_buff and passes it to t1_sge_tx.
 */
int t1_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct adapter *adapter = dev->priv;
        struct sge_port_stats *st = &adapter->sge->port_stats[dev->if_port];
        struct sge *sge = adapter->sge;
        struct cpl_tx_pkt *cpl;

#ifdef NETIF_F_TSO
        if (skb_shinfo(skb)->tso_size) {
                int eth_type;
                struct cpl_tx_pkt_lso *hdr;

                st->tso++;

                eth_type = skb->nh.raw - skb->data == ETH_HLEN ?
                        CPL_ETH_II : CPL_ETH_II_VLAN;

                hdr = (struct cpl_tx_pkt_lso *)skb_push(skb, sizeof(*hdr));
                hdr->opcode = CPL_TX_PKT_LSO;
                hdr->ip_csum_dis = hdr->l4_csum_dis = 0;
                hdr->ip_hdr_words = skb->nh.iph->ihl;
                hdr->tcp_hdr_words = skb->h.th->doff;
                hdr->eth_type_mss = htons(MK_ETH_TYPE_MSS(eth_type,
                                                skb_shinfo(skb)->tso_size));
                hdr->len = htonl(skb->len - sizeof(*hdr));
                cpl = (struct cpl_tx_pkt *)hdr;
                sge->stats.tx_lso_pkts++;
        } else
#endif
        {
                /*
                 * Packets shorter than ETH_HLEN can break the MAC, drop them
                 * early.  Also, we may get oversized packets because some
                 * parts of the kernel don't handle our unusual hard_header_len
                 * right, drop those too.
                 */
                if (unlikely(skb->len < ETH_HLEN ||
                             skb->len > dev->mtu + eth_hdr_len(skb->data))) {
                        dev_kfree_skb_any(skb);
                        return NETDEV_TX_OK;
                }

                /*
                 * We are using a non-standard hard_header_len and some kernel
                 * components, such as pktgen, do not handle it right.
                 * Complain when this happens but try to fix things up.
                 */
                if (unlikely(skb_headroom(skb) <
                             dev->hard_header_len - ETH_HLEN)) {
                        struct sk_buff *orig_skb = skb;

                        if (net_ratelimit())
                                printk(KERN_ERR "%s: inadequate headroom in "
                                       "Tx packet\n", dev->name);
                        skb = skb_realloc_headroom(skb, sizeof(*cpl));
                        dev_kfree_skb_any(orig_skb);
                        if (!skb)
                                return NETDEV_TX_OK;
                }

                if (!(adapter->flags & UDP_CSUM_CAPABLE) &&
                    skb->ip_summed == CHECKSUM_HW &&
                    skb->nh.iph->protocol == IPPROTO_UDP)
                        if (unlikely(skb_checksum_help(skb, 0))) {
                                dev_kfree_skb_any(skb);
                                return NETDEV_TX_OK;
                        }

                /* Hmmm, assuming to catch the gratious arp... and we'll use
                 * it to flush out stuck espi packets...
                  */
                if (unlikely(!adapter->sge->espibug_skb)) {
                        if (skb->protocol == htons(ETH_P_ARP) &&
                            skb->nh.arph->ar_op == htons(ARPOP_REQUEST)) {
                                adapter->sge->espibug_skb = skb;
                                /* We want to re-use this skb later. We
                                 * simply bump the reference count and it
                                 * will not be freed...
                                 */
                                skb = skb_get(skb);
                        }
                }

                cpl = (struct cpl_tx_pkt *)__skb_push(skb, sizeof(*cpl));
                cpl->opcode = CPL_TX_PKT;
                cpl->ip_csum_dis = 1;    /* SW calculates IP csum */
                cpl->l4_csum_dis = skb->ip_summed == CHECKSUM_HW ? 0 : 1;
                /* the length field isn't used so don't bother setting it */

                st->tx_cso += (skb->ip_summed == CHECKSUM_HW);
                sge->stats.tx_do_cksum += (skb->ip_summed == CHECKSUM_HW);
                sge->stats.tx_reg_pkts++;
        }
        cpl->iff = dev->if_port;

#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
        if (adapter->vlan_grp && vlan_tx_tag_present(skb)) {
                cpl->vlan_valid = 1;
                cpl->vlan = htons(vlan_tx_tag_get(skb));
                st->vlan_insert++;
        } else
#endif
                cpl->vlan_valid = 0;

        dev->trans_start = jiffies;
        return t1_sge_tx(skb, adapter, 0, dev);
}

/*
 * Callback for the Tx buffer reclaim timer.  Runs with softirqs disabled.
 */
static void sge_tx_reclaim_cb(unsigned long data)
{
        int i;
        struct sge *sge = (struct sge *)data;

        for (i = 0; i < SGE_CMDQ_N; ++i) {
                struct cmdQ *q = &sge->cmdQ[i];

                if (!spin_trylock(&q->lock))
                        continue;

                reclaim_completed_tx(sge, q);
                if (i == 0 && q->in_use)   /* flush pending credits */
                        writel(F_CMDQ0_ENABLE,
                                sge->adapter->regs + A_SG_DOORBELL);

                spin_unlock(&q->lock);
        }
        mod_timer(&sge->tx_reclaim_timer, jiffies + TX_RECLAIM_PERIOD);
}

/*
 * Propagate changes of the SGE coalescing parameters to the HW.
 */
int t1_sge_set_coalesce_params(struct sge *sge, struct sge_params *p)
{
        sge->netdev->poll = t1_poll;
        sge->fixed_intrtimer = p->rx_coalesce_usecs *
                core_ticks_per_usec(sge->adapter);
        writel(sge->fixed_intrtimer, sge->adapter->regs + A_SG_INTRTIMER);
        return 0;
}

/*
 * Allocates both RX and TX resources and configures the SGE. However,
 * the hardware is not enabled yet.
 */
int t1_sge_configure(struct sge *sge, struct sge_params *p)
{
        if (alloc_rx_resources(sge, p))
                return -ENOMEM;
        if (alloc_tx_resources(sge, p)) {
                free_rx_resources(sge);
                return -ENOMEM;
        }
        configure_sge(sge, p);

        /*
         * Now that we have sized the free lists calculate the payload
         * capacity of the large buffers.  Other parts of the driver use
         * this to set the max offload coalescing size so that RX packets
         * do not overflow our large buffers.
         */
        p->large_buf_capacity = jumbo_payload_capacity(sge);
        return 0;
}

/*
 * Disables the DMA engine.
 */
void t1_sge_stop(struct sge *sge)
{
        writel(0, sge->adapter->regs + A_SG_CONTROL);
        (void) readl(sge->adapter->regs + A_SG_CONTROL); /* flush */
        if (is_T2(sge->adapter))
                del_timer_sync(&sge->espibug_timer);
        del_timer_sync(&sge->tx_reclaim_timer);
}

/*
 * Enables the DMA engine.
 */
void t1_sge_start(struct sge *sge)
{
        refill_free_list(sge, &sge->freelQ[0]);
        refill_free_list(sge, &sge->freelQ[1]);

        writel(sge->sge_control, sge->adapter->regs + A_SG_CONTROL);
        doorbell_pio(sge->adapter, F_FL0_ENABLE | F_FL1_ENABLE);
        (void) readl(sge->adapter->regs + A_SG_CONTROL); /* flush */

        mod_timer(&sge->tx_reclaim_timer, jiffies + TX_RECLAIM_PERIOD);

        if (is_T2(sge->adapter)) 
                mod_timer(&sge->espibug_timer, jiffies + sge->espibug_timeout);
}

/*
 * Callback for the T2 ESPI 'stuck packet feature' workaorund
 */
static void espibug_workaround(void *data)
{
        struct adapter *adapter = (struct adapter *)data;
        struct sge *sge = adapter->sge;

        if (netif_running(adapter->port[0].dev)) {
                struct sk_buff *skb = sge->espibug_skb;

                u32 seop = t1_espi_get_mon(adapter, 0x930, 0);

                if ((seop & 0xfff0fff) == 0xfff && skb) {
                        if (!skb->cb[0]) {
                                u8 ch_mac_addr[ETH_ALEN] =
                                    {0x0, 0x7, 0x43, 0x0, 0x0, 0x0};
                                memcpy(skb->data + sizeof(struct cpl_tx_pkt),
                                    ch_mac_addr, ETH_ALEN);
                                memcpy(skb->data + skb->len - 10, ch_mac_addr,
                                    ETH_ALEN);
                                skb->cb[0] = 0xff;
                        }

                        /* bump the reference count to avoid freeing of the
                         * skb once the DMA has completed.
                         */
                        skb = skb_get(skb);
                        t1_sge_tx(skb, adapter, 0, adapter->port[0].dev);
                }
        }
        mod_timer(&sge->espibug_timer, jiffies + sge->espibug_timeout);
}

/*
 * Creates a t1_sge structure and returns suggested resource parameters.
 */
struct sge * __devinit t1_sge_create(struct adapter *adapter,
                                     struct sge_params *p)
{
        struct sge *sge = kmalloc(sizeof(*sge), GFP_KERNEL);

        if (!sge)
                return NULL;
        memset(sge, 0, sizeof(*sge));

        sge->adapter = adapter;
        sge->netdev = adapter->port[0].dev;
        sge->rx_pkt_pad = t1_is_T1B(adapter) ? 0 : 2;
        sge->jumbo_fl = t1_is_T1B(adapter) ? 1 : 0;

        init_timer(&sge->tx_reclaim_timer);
        sge->tx_reclaim_timer.data = (unsigned long)sge;
        sge->tx_reclaim_timer.function = sge_tx_reclaim_cb;

        if (is_T2(sge->adapter)) {
                init_timer(&sge->espibug_timer);
                sge->espibug_timer.function = (void *)&espibug_workaround;
                sge->espibug_timer.data = (unsigned long)sge->adapter;
                sge->espibug_timeout = 1;
        }
         

        p->cmdQ_size[0] = SGE_CMDQ0_E_N;
        p->cmdQ_size[1] = SGE_CMDQ1_E_N;
        p->freelQ_size[!sge->jumbo_fl] = SGE_FREEL_SIZE;
        p->freelQ_size[sge->jumbo_fl] = SGE_JUMBO_FREEL_SIZE;
        p->rx_coalesce_usecs =  50;
        p->coalesce_enable = 0;
        p->sample_interval_usecs = 0;
        p->polling = 0;

        return sge;
}