// SPDX-License-Identifier: GPL-2.0-only
/*
 * sgiseeq.c: Seeq8003 ethernet driver for SGI machines.
 *
 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
 */

#undef DEBUG

#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>

#include <asm/sgi/hpc3.h>
#include <asm/sgi/ip22.h>
#include <asm/sgi/seeq.h>

#include "sgiseeq.h"

static char *sgiseeqstr = "SGI Seeq8003";

/*
 * If you want speed, you do something silly, it always has worked for me.  So,
 * with that in mind, I've decided to make this driver look completely like a
 * stupid Lance from a driver architecture perspective.  Only difference is that
 * here our "ring buffer" looks and acts like a real Lance one does but is
 * laid out like how the HPC DMA and the Seeq want it to.  You'd be surprised
 * how a stupid idea like this can pay off in performance, not to mention
 * making this driver 2,000 times easier to write. ;-)
 */

/* Tune these if we tend to run out often etc. */
#define SEEQ_RX_BUFFERS  16
#define SEEQ_TX_BUFFERS  16

#define PKT_BUF_SZ       1584

#define NEXT_RX(i)  (((i) + 1) & (SEEQ_RX_BUFFERS - 1))
#define NEXT_TX(i)  (((i) + 1) & (SEEQ_TX_BUFFERS - 1))
#define PREV_RX(i)  (((i) - 1) & (SEEQ_RX_BUFFERS - 1))
#define PREV_TX(i)  (((i) - 1) & (SEEQ_TX_BUFFERS - 1))

#define TX_BUFFS_AVAIL(sp) ((sp->tx_old <= sp->tx_new) ? \
                            sp->tx_old + (SEEQ_TX_BUFFERS - 1) - sp->tx_new : \
                            sp->tx_old - sp->tx_new - 1)

#define VIRT_TO_DMA(sp, v) ((sp)->srings_dma +                                 \
                                  (dma_addr_t)((unsigned long)(v) -            \
                                               (unsigned long)((sp)->rx_desc)))

/* Copy frames shorter than rx_copybreak, otherwise pass on up in
 * a full sized sk_buff.  Value of 100 stolen from tulip.c (!alpha).
 */
static int rx_copybreak = 100;

#define PAD_SIZE    (128 - sizeof(struct hpc_dma_desc) - sizeof(void *))

struct sgiseeq_rx_desc {
        volatile struct hpc_dma_desc rdma;
        u8 padding[PAD_SIZE];
        struct sk_buff *skb;
};

struct sgiseeq_tx_desc {
        volatile struct hpc_dma_desc tdma;
        u8 padding[PAD_SIZE];
        struct sk_buff *skb;
};

/*
 * Warning: This structure is laid out in a certain way because HPC dma
 *          descriptors must be 8-byte aligned.  So don't touch this without
 *          some care.
 */
struct sgiseeq_init_block { /* Note the name ;-) */
        struct sgiseeq_rx_desc rxvector[SEEQ_RX_BUFFERS];
        struct sgiseeq_tx_desc txvector[SEEQ_TX_BUFFERS];
};

struct sgiseeq_private {
        struct sgiseeq_init_block *srings;
        dma_addr_t srings_dma;

        /* Ptrs to the descriptors in uncached space. */
        struct sgiseeq_rx_desc *rx_desc;
        struct sgiseeq_tx_desc *tx_desc;

        char *name;
        struct hpc3_ethregs *hregs;
        struct sgiseeq_regs *sregs;

        /* Ring entry counters. */
        unsigned int rx_new, tx_new;
        unsigned int rx_old, tx_old;

        int is_edlc;
        unsigned char control;
        unsigned char mode;

        spinlock_t tx_lock;
};

static inline void dma_sync_desc_cpu(struct net_device *dev, void *addr)
{
        struct sgiseeq_private *sp = netdev_priv(dev);

        dma_sync_single_for_cpu(dev->dev.parent, VIRT_TO_DMA(sp, addr),
                        sizeof(struct sgiseeq_rx_desc), DMA_BIDIRECTIONAL);
}

static inline void dma_sync_desc_dev(struct net_device *dev, void *addr)
{
        struct sgiseeq_private *sp = netdev_priv(dev);

        dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr),
                        sizeof(struct sgiseeq_rx_desc), DMA_BIDIRECTIONAL);
}

static inline void hpc3_eth_reset(struct hpc3_ethregs *hregs)
{
        hregs->reset = HPC3_ERST_CRESET | HPC3_ERST_CLRIRQ;
        udelay(20);
        hregs->reset = 0;
}

static inline void reset_hpc3_and_seeq(struct hpc3_ethregs *hregs,
                                       struct sgiseeq_regs *sregs)
{
        hregs->rx_ctrl = hregs->tx_ctrl = 0;
        hpc3_eth_reset(hregs);
}

#define RSTAT_GO_BITS (SEEQ_RCMD_IGOOD | SEEQ_RCMD_IEOF | SEEQ_RCMD_ISHORT | \
                       SEEQ_RCMD_IDRIB | SEEQ_RCMD_ICRC)

static inline void seeq_go(struct sgiseeq_private *sp,
                           struct hpc3_ethregs *hregs,
                           struct sgiseeq_regs *sregs)
{
        sregs->rstat = sp->mode | RSTAT_GO_BITS;
        hregs->rx_ctrl = HPC3_ERXCTRL_ACTIVE;
}

static inline void __sgiseeq_set_mac_address(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct sgiseeq_regs *sregs = sp->sregs;
        int i;

        sregs->tstat = SEEQ_TCMD_RB0;
        for (i = 0; i < 6; i++)
                sregs->rw.eth_addr[i] = dev->dev_addr[i];
}

static int sgiseeq_set_mac_address(struct net_device *dev, void *addr)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct sockaddr *sa = addr;

        eth_hw_addr_set(dev, sa->sa_data);

        spin_lock_irq(&sp->tx_lock);
        __sgiseeq_set_mac_address(dev);
        spin_unlock_irq(&sp->tx_lock);

        return 0;
}

#define TCNTINFO_INIT (HPCDMA_EOX | HPCDMA_ETXD)
#define RCNTCFG_INIT  (HPCDMA_OWN | HPCDMA_EORP | HPCDMA_XIE)
#define RCNTINFO_INIT (RCNTCFG_INIT | (PKT_BUF_SZ & HPCDMA_BCNT))

static int seeq_init_ring(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        int i;

        netif_stop_queue(dev);
        sp->rx_new = sp->tx_new = 0;
        sp->rx_old = sp->tx_old = 0;

        __sgiseeq_set_mac_address(dev);

        /* Setup tx ring. */
        for(i = 0; i < SEEQ_TX_BUFFERS; i++) {
                sp->tx_desc[i].tdma.cntinfo = TCNTINFO_INIT;
                dma_sync_desc_dev(dev, &sp->tx_desc[i]);
        }

        /* And now the rx ring. */
        for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
                if (!sp->rx_desc[i].skb) {
                        dma_addr_t dma_addr;
                        struct sk_buff *skb = netdev_alloc_skb(dev, PKT_BUF_SZ);

                        if (skb == NULL)
                                return -ENOMEM;
                        skb_reserve(skb, 2);
                        dma_addr = dma_map_single(dev->dev.parent,
                                                  skb->data - 2,
                                                  PKT_BUF_SZ, DMA_FROM_DEVICE);
                        sp->rx_desc[i].skb = skb;
                        sp->rx_desc[i].rdma.pbuf = dma_addr;
                }
                sp->rx_desc[i].rdma.cntinfo = RCNTINFO_INIT;
                dma_sync_desc_dev(dev, &sp->rx_desc[i]);
        }
        sp->rx_desc[i - 1].rdma.cntinfo |= HPCDMA_EOR;
        dma_sync_desc_dev(dev, &sp->rx_desc[i - 1]);
        return 0;
}

static void seeq_purge_ring(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        int i;

        /* clear tx ring. */
        for (i = 0; i < SEEQ_TX_BUFFERS; i++) {
                if (sp->tx_desc[i].skb) {
                        dev_kfree_skb(sp->tx_desc[i].skb);
                        sp->tx_desc[i].skb = NULL;
                }
        }

        /* And now the rx ring. */
        for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
                if (sp->rx_desc[i].skb) {
                        dev_kfree_skb(sp->rx_desc[i].skb);
                        sp->rx_desc[i].skb = NULL;
                }
        }
}

#ifdef DEBUG
static struct sgiseeq_private *gpriv;
static struct net_device *gdev;

static void sgiseeq_dump_rings(void)
{
        static int once;
        struct sgiseeq_rx_desc *r = gpriv->rx_desc;
        struct sgiseeq_tx_desc *t = gpriv->tx_desc;
        struct hpc3_ethregs *hregs = gpriv->hregs;
        int i;

        if (once)
                return;
        once++;
        printk("RING DUMP:\n");
        for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
                printk("RX [%d]: @(%p) [%08x,%08x,%08x] ",
                       i, (&r[i]), r[i].rdma.pbuf, r[i].rdma.cntinfo,
                       r[i].rdma.pnext);
                i += 1;
                printk("-- [%d]: @(%p) [%08x,%08x,%08x]\n",
                       i, (&r[i]), r[i].rdma.pbuf, r[i].rdma.cntinfo,
                       r[i].rdma.pnext);
        }
        for (i = 0; i < SEEQ_TX_BUFFERS; i++) {
                printk("TX [%d]: @(%p) [%08x,%08x,%08x] ",
                       i, (&t[i]), t[i].tdma.pbuf, t[i].tdma.cntinfo,
                       t[i].tdma.pnext);
                i += 1;
                printk("-- [%d]: @(%p) [%08x,%08x,%08x]\n",
                       i, (&t[i]), t[i].tdma.pbuf, t[i].tdma.cntinfo,
                       t[i].tdma.pnext);
        }
        printk("INFO: [rx_new = %d rx_old=%d] [tx_new = %d tx_old = %d]\n",
               gpriv->rx_new, gpriv->rx_old, gpriv->tx_new, gpriv->tx_old);
        printk("RREGS: rx_cbptr[%08x] rx_ndptr[%08x] rx_ctrl[%08x]\n",
               hregs->rx_cbptr, hregs->rx_ndptr, hregs->rx_ctrl);
        printk("TREGS: tx_cbptr[%08x] tx_ndptr[%08x] tx_ctrl[%08x]\n",
               hregs->tx_cbptr, hregs->tx_ndptr, hregs->tx_ctrl);
}
#endif

#define TSTAT_INIT_SEEQ (SEEQ_TCMD_IPT|SEEQ_TCMD_I16|SEEQ_TCMD_IC|SEEQ_TCMD_IUF)
#define TSTAT_INIT_EDLC ((TSTAT_INIT_SEEQ) | SEEQ_TCMD_RB2)

static int init_seeq(struct net_device *dev, struct sgiseeq_private *sp,
                     struct sgiseeq_regs *sregs)
{
        struct hpc3_ethregs *hregs = sp->hregs;
        int err;

        reset_hpc3_and_seeq(hregs, sregs);
        err = seeq_init_ring(dev);
        if (err)
                return err;

        /* Setup to field the proper interrupt types. */
        if (sp->is_edlc) {
                sregs->tstat = TSTAT_INIT_EDLC;
                sregs->rw.wregs.control = sp->control;
                sregs->rw.wregs.frame_gap = 0;
        } else {
                sregs->tstat = TSTAT_INIT_SEEQ;
        }

        hregs->rx_ndptr = VIRT_TO_DMA(sp, sp->rx_desc);
        hregs->tx_ndptr = VIRT_TO_DMA(sp, sp->tx_desc);

        seeq_go(sp, hregs, sregs);
        return 0;
}

static void record_rx_errors(struct net_device *dev, unsigned char status)
{
        if (status & SEEQ_RSTAT_OVERF ||
            status & SEEQ_RSTAT_SFRAME)
                dev->stats.rx_over_errors++;
        if (status & SEEQ_RSTAT_CERROR)
                dev->stats.rx_crc_errors++;
        if (status & SEEQ_RSTAT_DERROR)
                dev->stats.rx_frame_errors++;
        if (status & SEEQ_RSTAT_REOF)
                dev->stats.rx_errors++;
}

static inline void rx_maybe_restart(struct sgiseeq_private *sp,
                                    struct hpc3_ethregs *hregs,
                                    struct sgiseeq_regs *sregs)
{
        if (!(hregs->rx_ctrl & HPC3_ERXCTRL_ACTIVE)) {
                hregs->rx_ndptr = VIRT_TO_DMA(sp, sp->rx_desc + sp->rx_new);
                seeq_go(sp, hregs, sregs);
        }
}

static inline void sgiseeq_rx(struct net_device *dev, struct sgiseeq_private *sp,
                              struct hpc3_ethregs *hregs,
                              struct sgiseeq_regs *sregs)
{
        struct sgiseeq_rx_desc *rd;
        struct sk_buff *skb = NULL;
        struct sk_buff *newskb;
        unsigned char pkt_status;
        int len = 0;
        unsigned int orig_end = PREV_RX(sp->rx_new);

        /* Service every received packet. */
        rd = &sp->rx_desc[sp->rx_new];
        dma_sync_desc_cpu(dev, rd);
        while (!(rd->rdma.cntinfo & HPCDMA_OWN)) {
                len = PKT_BUF_SZ - (rd->rdma.cntinfo & HPCDMA_BCNT) - 3;
                dma_unmap_single(dev->dev.parent, rd->rdma.pbuf,
                                 PKT_BUF_SZ, DMA_FROM_DEVICE);
                pkt_status = rd->skb->data[len];
                if (pkt_status & SEEQ_RSTAT_FIG) {
                        /* Packet is OK. */
                        /* We don't want to receive our own packets */
                        if (!ether_addr_equal(rd->skb->data + 6, dev->dev_addr)) {
                                if (len > rx_copybreak) {
                                        skb = rd->skb;
                                        newskb = netdev_alloc_skb(dev, PKT_BUF_SZ);
                                        if (!newskb) {
                                                newskb = skb;
                                                skb = NULL;
                                                goto memory_squeeze;
                                        }
                                        skb_reserve(newskb, 2);
                                } else {
                                        skb = netdev_alloc_skb_ip_align(dev, len);
                                        if (skb)
                                                skb_copy_to_linear_data(skb, rd->skb->data, len);

                                        newskb = rd->skb;
                                }
memory_squeeze:
                                if (skb) {
                                        skb_put(skb, len);
                                        skb->protocol = eth_type_trans(skb, dev);
                                        netif_rx(skb);
                                        dev->stats.rx_packets++;
                                        dev->stats.rx_bytes += len;
                                } else {
                                        dev->stats.rx_dropped++;
                                }
                        } else {
                                /* Silently drop my own packets */
                                newskb = rd->skb;
                        }
                } else {
                        record_rx_errors(dev, pkt_status);
                        newskb = rd->skb;
                }
                rd->skb = newskb;
                rd->rdma.pbuf = dma_map_single(dev->dev.parent,
                                               newskb->data - 2,
                                               PKT_BUF_SZ, DMA_FROM_DEVICE);

                /* Return the entry to the ring pool. */
                rd->rdma.cntinfo = RCNTINFO_INIT;
                sp->rx_new = NEXT_RX(sp->rx_new);
                dma_sync_desc_dev(dev, rd);
                rd = &sp->rx_desc[sp->rx_new];
                dma_sync_desc_cpu(dev, rd);
        }
        dma_sync_desc_dev(dev, rd);

        dma_sync_desc_cpu(dev, &sp->rx_desc[orig_end]);
        sp->rx_desc[orig_end].rdma.cntinfo &= ~(HPCDMA_EOR);
        dma_sync_desc_dev(dev, &sp->rx_desc[orig_end]);
        dma_sync_desc_cpu(dev, &sp->rx_desc[PREV_RX(sp->rx_new)]);
        sp->rx_desc[PREV_RX(sp->rx_new)].rdma.cntinfo |= HPCDMA_EOR;
        dma_sync_desc_dev(dev, &sp->rx_desc[PREV_RX(sp->rx_new)]);
        rx_maybe_restart(sp, hregs, sregs);
}

static inline void tx_maybe_reset_collisions(struct sgiseeq_private *sp,
                                             struct sgiseeq_regs *sregs)
{
        if (sp->is_edlc) {
                sregs->rw.wregs.control = sp->control & ~(SEEQ_CTRL_XCNT);
                sregs->rw.wregs.control = sp->control;
        }
}

static inline void kick_tx(struct net_device *dev,
                           struct sgiseeq_private *sp,
                           struct hpc3_ethregs *hregs)
{
        struct sgiseeq_tx_desc *td;
        int i = sp->tx_old;

        /* If the HPC aint doin nothin, and there are more packets
         * with ETXD cleared and XIU set we must make very certain
         * that we restart the HPC else we risk locking up the
         * adapter.  The following code is only safe iff the HPCDMA
         * is not active!
         */
        td = &sp->tx_desc[i];
        dma_sync_desc_cpu(dev, td);
        while ((td->tdma.cntinfo & (HPCDMA_XIU | HPCDMA_ETXD)) ==
              (HPCDMA_XIU | HPCDMA_ETXD)) {
                i = NEXT_TX(i);
                td = &sp->tx_desc[i];
                dma_sync_desc_cpu(dev, td);
        }
        if (td->tdma.cntinfo & HPCDMA_XIU) {
                dma_sync_desc_dev(dev, td);
                hregs->tx_ndptr = VIRT_TO_DMA(sp, td);
                hregs->tx_ctrl = HPC3_ETXCTRL_ACTIVE;
        }
}

static inline void sgiseeq_tx(struct net_device *dev, struct sgiseeq_private *sp,
                              struct hpc3_ethregs *hregs,
                              struct sgiseeq_regs *sregs)
{
        struct sgiseeq_tx_desc *td;
        unsigned long status = hregs->tx_ctrl;
        int j;

        tx_maybe_reset_collisions(sp, sregs);

        if (!(status & (HPC3_ETXCTRL_ACTIVE | SEEQ_TSTAT_PTRANS))) {
                /* Oops, HPC detected some sort of error. */
                if (status & SEEQ_TSTAT_R16)
                        dev->stats.tx_aborted_errors++;
                if (status & SEEQ_TSTAT_UFLOW)
                        dev->stats.tx_fifo_errors++;
                if (status & SEEQ_TSTAT_LCLS)
                        dev->stats.collisions++;
        }

        /* Ack 'em... */
        for (j = sp->tx_old; j != sp->tx_new; j = NEXT_TX(j)) {
                td = &sp->tx_desc[j];

                dma_sync_desc_cpu(dev, td);
                if (!(td->tdma.cntinfo & (HPCDMA_XIU)))
                        break;
                if (!(td->tdma.cntinfo & (HPCDMA_ETXD))) {
                        dma_sync_desc_dev(dev, td);
                        if (!(status & HPC3_ETXCTRL_ACTIVE)) {
                                hregs->tx_ndptr = VIRT_TO_DMA(sp, td);
                                hregs->tx_ctrl = HPC3_ETXCTRL_ACTIVE;
                        }
                        break;
                }
                dev->stats.tx_packets++;
                sp->tx_old = NEXT_TX(sp->tx_old);
                td->tdma.cntinfo &= ~(HPCDMA_XIU | HPCDMA_XIE);
                td->tdma.cntinfo |= HPCDMA_EOX;
                if (td->skb) {
                        dev_kfree_skb_any(td->skb);
                        td->skb = NULL;
                }
                dma_sync_desc_dev(dev, td);
        }
}

static irqreturn_t sgiseeq_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *) dev_id;
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct hpc3_ethregs *hregs = sp->hregs;
        struct sgiseeq_regs *sregs = sp->sregs;

        spin_lock(&sp->tx_lock);

        /* Ack the IRQ and set software state. */
        hregs->reset = HPC3_ERST_CLRIRQ;

        /* Always check for received packets. */
        sgiseeq_rx(dev, sp, hregs, sregs);

        /* Only check for tx acks if we have something queued. */
        if (sp->tx_old != sp->tx_new)
                sgiseeq_tx(dev, sp, hregs, sregs);

        if ((TX_BUFFS_AVAIL(sp) > 0) && netif_queue_stopped(dev)) {
                netif_wake_queue(dev);
        }
        spin_unlock(&sp->tx_lock);

        return IRQ_HANDLED;
}

static int sgiseeq_open(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct sgiseeq_regs *sregs = sp->sregs;
        unsigned int irq = dev->irq;
        int err;

        if (request_irq(irq, sgiseeq_interrupt, 0, sgiseeqstr, dev)) {
                printk(KERN_ERR "Seeq8003: Can't get irq %d\n", dev->irq);
                return -EAGAIN;
        }

        err = init_seeq(dev, sp, sregs);
        if (err)
                goto out_free_irq;

        netif_start_queue(dev);

        return 0;

out_free_irq:
        free_irq(irq, dev);

        return err;
}

static int sgiseeq_close(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct sgiseeq_regs *sregs = sp->sregs;
        unsigned int irq = dev->irq;

        netif_stop_queue(dev);

        /* Shutdown the Seeq. */
        reset_hpc3_and_seeq(sp->hregs, sregs);
        free_irq(irq, dev);
        seeq_purge_ring(dev);

        return 0;
}

static inline int sgiseeq_reset(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct sgiseeq_regs *sregs = sp->sregs;
        int err;

        err = init_seeq(dev, sp, sregs);
        if (err)
                return err;

        netif_trans_update(dev); /* prevent tx timeout */
        netif_wake_queue(dev);

        return 0;
}

static netdev_tx_t
sgiseeq_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        struct hpc3_ethregs *hregs = sp->hregs;
        unsigned long flags;
        struct sgiseeq_tx_desc *td;
        int len, entry;

        spin_lock_irqsave(&sp->tx_lock, flags);

        /* Setup... */
        len = skb->len;
        if (len < ETH_ZLEN) {
                if (skb_padto(skb, ETH_ZLEN)) {
                        spin_unlock_irqrestore(&sp->tx_lock, flags);
                        return NETDEV_TX_OK;
                }
                len = ETH_ZLEN;
        }

        dev->stats.tx_bytes += len;
        entry = sp->tx_new;
        td = &sp->tx_desc[entry];
        dma_sync_desc_cpu(dev, td);

        /* Create entry.  There are so many races with adding a new
         * descriptor to the chain:
         * 1) Assume that the HPC is off processing a DMA chain while
         *    we are changing all of the following.
         * 2) Do no allow the HPC to look at a new descriptor until
         *    we have completely set up it's state.  This means, do
         *    not clear HPCDMA_EOX in the current last descritptor
         *    until the one we are adding looks consistent and could
         *    be processes right now.
         * 3) The tx interrupt code must notice when we've added a new
         *    entry and the HPC got to the end of the chain before we
         *    added this new entry and restarted it.
         */
        td->skb = skb;
        td->tdma.pbuf = dma_map_single(dev->dev.parent, skb->data,
                                       len, DMA_TO_DEVICE);
        td->tdma.cntinfo = (len & HPCDMA_BCNT) |
                           HPCDMA_XIU | HPCDMA_EOXP | HPCDMA_XIE | HPCDMA_EOX;
        dma_sync_desc_dev(dev, td);
        if (sp->tx_old != sp->tx_new) {
                struct sgiseeq_tx_desc *backend;

                backend = &sp->tx_desc[PREV_TX(sp->tx_new)];
                dma_sync_desc_cpu(dev, backend);
                backend->tdma.cntinfo &= ~HPCDMA_EOX;
                dma_sync_desc_dev(dev, backend);
        }
        sp->tx_new = NEXT_TX(sp->tx_new); /* Advance. */

        /* Maybe kick the HPC back into motion. */
        if (!(hregs->tx_ctrl & HPC3_ETXCTRL_ACTIVE))
                kick_tx(dev, sp, hregs);

        if (!TX_BUFFS_AVAIL(sp))
                netif_stop_queue(dev);
        spin_unlock_irqrestore(&sp->tx_lock, flags);

        return NETDEV_TX_OK;
}

static void timeout(struct net_device *dev, unsigned int txqueue)
{
        printk(KERN_NOTICE "%s: transmit timed out, resetting\n", dev->name);
        sgiseeq_reset(dev);

        netif_trans_update(dev); /* prevent tx timeout */
        netif_wake_queue(dev);
}

static void sgiseeq_set_multicast(struct net_device *dev)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        unsigned char oldmode = sp->mode;

        if(dev->flags & IFF_PROMISC)
                sp->mode = SEEQ_RCMD_RANY;
        else if ((dev->flags & IFF_ALLMULTI) || !netdev_mc_empty(dev))
                sp->mode = SEEQ_RCMD_RBMCAST;
        else
                sp->mode = SEEQ_RCMD_RBCAST;

        /* XXX I know this sucks, but is there a better way to reprogram
         * XXX the receiver? At least, this shouldn't happen too often.
         */

        if (oldmode != sp->mode)
                sgiseeq_reset(dev);
}

static inline void setup_tx_ring(struct net_device *dev,
                                 struct sgiseeq_tx_desc *buf,
                                 int nbufs)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        int i = 0;

        while (i < (nbufs - 1)) {
                buf[i].tdma.pnext = VIRT_TO_DMA(sp, buf + i + 1);
                buf[i].tdma.pbuf = 0;
                dma_sync_desc_dev(dev, &buf[i]);
                i++;
        }
        buf[i].tdma.pnext = VIRT_TO_DMA(sp, buf);
        dma_sync_desc_dev(dev, &buf[i]);
}

static inline void setup_rx_ring(struct net_device *dev,
                                 struct sgiseeq_rx_desc *buf,
                                 int nbufs)
{
        struct sgiseeq_private *sp = netdev_priv(dev);
        int i = 0;

        while (i < (nbufs - 1)) {
                buf[i].rdma.pnext = VIRT_TO_DMA(sp, buf + i + 1);
                buf[i].rdma.pbuf = 0;
                dma_sync_desc_dev(dev, &buf[i]);
                i++;
        }
        buf[i].rdma.pbuf = 0;
        buf[i].rdma.pnext = VIRT_TO_DMA(sp, buf);
        dma_sync_desc_dev(dev, &buf[i]);
}

static const struct net_device_ops sgiseeq_netdev_ops = {
        .ndo_open               = sgiseeq_open,
        .ndo_stop               = sgiseeq_close,
        .ndo_start_xmit         = sgiseeq_start_xmit,
        .ndo_tx_timeout         = timeout,
        .ndo_set_rx_mode        = sgiseeq_set_multicast,
        .ndo_set_mac_address    = sgiseeq_set_mac_address,
        .ndo_validate_addr      = eth_validate_addr,
};

static int sgiseeq_probe(struct platform_device *pdev)
{
        struct sgiseeq_platform_data *pd = dev_get_platdata(&pdev->dev);
        struct hpc3_regs *hpcregs = pd->hpc;
        struct sgiseeq_init_block *sr;
        unsigned int irq = pd->irq;
        struct sgiseeq_private *sp;
        struct net_device *dev;
        int err;

        dev = alloc_etherdev(sizeof (struct sgiseeq_private));
        if (!dev) {
                err = -ENOMEM;
                goto err_out;
        }

        platform_set_drvdata(pdev, dev);
        SET_NETDEV_DEV(dev, &pdev->dev);
        sp = netdev_priv(dev);

        /* Make private data page aligned */
        sr = dma_alloc_noncoherent(&pdev->dev, sizeof(*sp->srings),
                        &sp->srings_dma, DMA_BIDIRECTIONAL, GFP_KERNEL);
        if (!sr) {
                printk(KERN_ERR "Sgiseeq: Page alloc failed, aborting.\n");
                err = -ENOMEM;
                goto err_out_free_dev;
        }
        sp->srings = sr;
        sp->rx_desc = sp->srings->rxvector;
        sp->tx_desc = sp->srings->txvector;
        spin_lock_init(&sp->tx_lock);

        /* A couple calculations now, saves many cycles later. */
        setup_rx_ring(dev, sp->rx_desc, SEEQ_RX_BUFFERS);
        setup_tx_ring(dev, sp->tx_desc, SEEQ_TX_BUFFERS);

        eth_hw_addr_set(dev, pd->mac);

#ifdef DEBUG
        gpriv = sp;
        gdev = dev;
#endif
        sp->sregs = (struct sgiseeq_regs *) &hpcregs->eth_ext[0];
        sp->hregs = &hpcregs->ethregs;
        sp->name = sgiseeqstr;
        sp->mode = SEEQ_RCMD_RBCAST;

        /* Setup PIO and DMA transfer timing */
        sp->hregs->pconfig = 0x161;
        sp->hregs->dconfig = HPC3_EDCFG_FIRQ | HPC3_EDCFG_FEOP |
                             HPC3_EDCFG_FRXDC | HPC3_EDCFG_PTO | 0x026;

        /* Setup PIO and DMA transfer timing */
        sp->hregs->pconfig = 0x161;
        sp->hregs->dconfig = HPC3_EDCFG_FIRQ | HPC3_EDCFG_FEOP |
                             HPC3_EDCFG_FRXDC | HPC3_EDCFG_PTO | 0x026;

        /* Reset the chip. */
        hpc3_eth_reset(sp->hregs);

        sp->is_edlc = !(sp->sregs->rw.rregs.collision_tx[0] & 0xff);
        if (sp->is_edlc)
                sp->control = SEEQ_CTRL_XCNT | SEEQ_CTRL_ACCNT |
                              SEEQ_CTRL_SFLAG | SEEQ_CTRL_ESHORT |
                              SEEQ_CTRL_ENCARR;

        dev->netdev_ops         = &sgiseeq_netdev_ops;
        dev->watchdog_timeo     = (200 * HZ) / 1000;
        dev->irq                = irq;

        if (register_netdev(dev)) {
                printk(KERN_ERR "Sgiseeq: Cannot register net device, "
                       "aborting.\n");
                err = -ENODEV;
                goto err_out_free_attrs;
        }

        printk(KERN_INFO "%s: %s %pM\n", dev->name, sgiseeqstr, dev->dev_addr);

        return 0;

err_out_free_attrs:
        dma_free_noncoherent(&pdev->dev, sizeof(*sp->srings), sp->srings,
                       sp->srings_dma, DMA_BIDIRECTIONAL);
err_out_free_dev:
        free_netdev(dev);

err_out:
        return err;
}

static void sgiseeq_remove(struct platform_device *pdev)
{
        struct net_device *dev = platform_get_drvdata(pdev);
        struct sgiseeq_private *sp = netdev_priv(dev);

        unregister_netdev(dev);
        dma_free_noncoherent(&pdev->dev, sizeof(*sp->srings), sp->srings,
                       sp->srings_dma, DMA_BIDIRECTIONAL);
        free_netdev(dev);
}

static struct platform_driver sgiseeq_driver = {
        .probe  = sgiseeq_probe,
        .remove = sgiseeq_remove,
        .driver = {
                .name   = "sgiseeq",
        }
};

module_platform_driver(sgiseeq_driver);

MODULE_DESCRIPTION("SGI Seeq 8003 driver");
MODULE_AUTHOR("Linux/MIPS Mailing List <linux-mips@linux-mips.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:sgiseeq");