xref: /src/sys/arch/sgimips/hpc/if_sq.c

/*	$NetBSD: if_sq.c,v 1.60 2024/07/05 04:31:50 rin Exp $	*/

/*
 * Copyright (c) 2001 Rafal K. Boni
 * Copyright (c) 1998, 1999, 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Portions of this code are derived from software contributed to The
 * NetBSD Foundation by Jason R. Thorpe of the Numerical Aerospace
 * Simulation Facility, NASA Ames Research Center.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_sq.c,v 1.60 2024/07/05 04:31:50 rin Exp $");


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/callout.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/syslog.h>

#include <uvm/uvm_extern.h>

#include <machine/endian.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_ether.h>

#include <net/bpf.h>

#include <sys/bus.h>
#include <machine/intr.h>
#include <machine/sysconf.h>

#include <dev/ic/seeq8003reg.h>

#include <sgimips/hpc/sqvar.h>
#include <sgimips/hpc/hpcvar.h>
#include <sgimips/hpc/hpcreg.h>

#include <dev/arcbios/arcbios.h>
#include <dev/arcbios/arcbiosvar.h>

#define static

/*
 * Short TODO list:
 *	(1) Do counters for bad-RX packets.
 *	(2) Allow multi-segment transmits, instead of copying to a single,
 *	    contiguous mbuf.
 *	(3) Verify sq_stop() turns off enough stuff; I was still getting
 *	    seeq interrupts after sq_stop().
 *	(4) Implement EDLC modes: especially packet auto-pad and simplex
 *	    mode.
 *	(5) Should the driver filter out its own transmissions in non-EDLC
 *	    mode?
 *	(6) Multicast support -- multicast filter, address management, ...
 *	(7) Deal with RB0 (recv buffer overflow) on reception.  Will need
 *	    to figure out if RB0 is read-only as stated in one spot in the
 *	    HPC spec or read-write (ie, is the 'write a one to clear it')
 *	    the correct thing?
 */

#if defined(SQ_DEBUG)
 int sq_debug = 0;
 #define SQ_DPRINTF(x) if (sq_debug) printf x
#else
 #define SQ_DPRINTF(x)
#endif

static int	sq_match(device_t, cfdata_t, void *);
static void	sq_attach(device_t, device_t, void *);
static int	sq_init(struct ifnet *);
static void	sq_start(struct ifnet *);
static void	sq_stop(struct ifnet *, int);
static void	sq_watchdog(struct ifnet *);
static int	sq_ioctl(struct ifnet *, u_long, void *);

static void	sq_set_filter(struct sq_softc *);
static int	sq_intr(void *);
static int	sq_rxintr(struct sq_softc *);
static int	sq_txintr(struct sq_softc *);
static void	sq_txring_hpc1(struct sq_softc *);
static void	sq_txring_hpc3(struct sq_softc *);
static void	sq_reset(struct sq_softc *);
static int	sq_add_rxbuf(struct sq_softc *, int);
static void	sq_dump_buffer(paddr_t, psize_t);
static void	sq_trace_dump(struct sq_softc *);

CFATTACH_DECL_NEW(sq, sizeof(struct sq_softc),
    sq_match, sq_attach, NULL, NULL);

#define ETHER_PAD_LEN (ETHER_MIN_LEN - ETHER_CRC_LEN)

#define sq_seeq_read(sc, off) \
	bus_space_read_1(sc->sc_regt, sc->sc_regh, (off << 2) + 3)
#define sq_seeq_write(sc, off, val) \
	bus_space_write_1(sc->sc_regt, sc->sc_regh, (off << 2) + 3, val)

#define sq_hpc_read(sc, off) \
	bus_space_read_4(sc->sc_hpct, sc->sc_hpch, off)
#define sq_hpc_write(sc, off, val) \
	bus_space_write_4(sc->sc_hpct, sc->sc_hpch, off, val)

/* MAC address offset for non-onboard implementations */
#define SQ_HPC_EEPROM_ENADDR	250

#define SGI_OUI_0		0x08
#define SGI_OUI_1		0x00
#define SGI_OUI_2		0x69

static int
sq_match(device_t parent, cfdata_t cf, void *aux)
{
	struct hpc_attach_args *ha = aux;

	if (strcmp(ha->ha_name, cf->cf_name) == 0) {
		vaddr_t reset, txstat;

		reset = MIPS_PHYS_TO_KSEG1(ha->ha_sh +
		    ha->ha_dmaoff + ha->hpc_regs->enetr_reset);
		txstat = MIPS_PHYS_TO_KSEG1(ha->ha_sh +
		    ha->ha_devoff + (SEEQ_TXSTAT << 2));

		if (platform.badaddr((void *)reset, sizeof(reset)))
			return 0;

		*(volatile uint32_t *)reset = 0x1;
		delay(20);
		*(volatile uint32_t *)reset = 0x0;

		if (platform.badaddr((void *)txstat, sizeof(txstat)))
			return 0;

		if ((*(volatile uint32_t *)txstat & 0xff) == TXSTAT_OLDNEW)
			return 1;
	}

	return 0;
}

static void
sq_attach(device_t parent, device_t self, void *aux)
{
	int i, err;
	const char* macaddr;
	struct sq_softc *sc = device_private(self);
	struct hpc_attach_args *haa = aux;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;

	sc->sc_dev = self;
	sc->sc_hpct = haa->ha_st;
	sc->hpc_regs = haa->hpc_regs;	   /* HPC register definitions */

	if ((err = bus_space_subregion(haa->ha_st, haa->ha_sh,
	    haa->ha_dmaoff, sc->hpc_regs->enet_regs_size,
	    &sc->sc_hpch)) != 0) {
		printf(": unable to map HPC DMA registers, error = %d\n", err);
		goto fail_0;
	}

	sc->sc_regt = haa->ha_st;
	if ((err = bus_space_subregion(haa->ha_st, haa->ha_sh,
	    haa->ha_devoff, sc->hpc_regs->enet_devregs_size,
	    &sc->sc_regh)) != 0) {
		printf(": unable to map Seeq registers, error = %d\n", err);
		goto fail_0;
	}

	sc->sc_dmat = haa->ha_dmat;

	if ((err = bus_dmamem_alloc(sc->sc_dmat, sizeof(struct sq_control),
	    PAGE_SIZE, PAGE_SIZE, &sc->sc_cdseg, 1, &sc->sc_ncdseg,
	    BUS_DMA_NOWAIT)) != 0) {
		printf(": unable to allocate control data, error = %d\n", err);
		goto fail_0;
	}

	if ((err = bus_dmamem_map(sc->sc_dmat, &sc->sc_cdseg, sc->sc_ncdseg,
	    sizeof(struct sq_control), (void **)&sc->sc_control,
	    BUS_DMA_NOWAIT | BUS_DMA_COHERENT)) != 0) {
		printf(": unable to map control data, error = %d\n", err);
		goto fail_1;
	}

	if ((err = bus_dmamap_create(sc->sc_dmat,
	    sizeof(struct sq_control), 1, sizeof(struct sq_control), PAGE_SIZE,
	    BUS_DMA_NOWAIT, &sc->sc_cdmap)) != 0) {
		printf(": unable to create DMA map for control data, error "
		    "= %d\n", err);
		goto fail_2;
	}

	if ((err = bus_dmamap_load(sc->sc_dmat, sc->sc_cdmap,
	    sc->sc_control, sizeof(struct sq_control), NULL,
	    BUS_DMA_NOWAIT)) != 0) {
		printf(": unable to load DMA map for control data, error "
		    "= %d\n", err);
		goto fail_3;
	}

	memset(sc->sc_control, 0, sizeof(struct sq_control));

	/* Create transmit buffer DMA maps */
	for (i = 0; i < SQ_NTXDESC; i++) {
		if ((err = bus_dmamap_create(sc->sc_dmat,
		    MCLBYTES, 1, MCLBYTES, 0,
		    BUS_DMA_NOWAIT, &sc->sc_txmap[i])) != 0) {
			printf(": unable to create tx DMA map %d, error = %d\n",
			    i, err);
			goto fail_4;
		}
	}

	/* Create receive buffer DMA maps */
	for (i = 0; i < SQ_NRXDESC; i++) {
		if ((err = bus_dmamap_create(sc->sc_dmat,
		    MCLBYTES, 1, MCLBYTES, 0,
		    BUS_DMA_NOWAIT, &sc->sc_rxmap[i])) != 0) {
			printf(": unable to create rx DMA map %d, error = %d\n",
			    i, err);
			goto fail_5;
		}
	}

	/* Pre-allocate the receive buffers.  */
	for (i = 0; i < SQ_NRXDESC; i++) {
		if ((err = sq_add_rxbuf(sc, i)) != 0) {
			printf(": unable to allocate or map rx buffer %d\n,"
			    " error = %d\n", i, err);
			goto fail_6;
		}
	}

	memcpy(sc->sc_enaddr, &haa->hpc_eeprom[SQ_HPC_EEPROM_ENADDR],
	    ETHER_ADDR_LEN);

	/*
	 * If our mac address is bogus, obtain it from ARCBIOS. This will
	 * be true of the onboard HPC3 on IP22, since there is no eeprom,
	 * but rather the DS1386 RTC's battery-backed ram is used.
	 */
	if (sc->sc_enaddr[0] != SGI_OUI_0 ||
	    sc->sc_enaddr[1] != SGI_OUI_1 ||
	    sc->sc_enaddr[2] != SGI_OUI_2) {
		macaddr = arcbios_GetEnvironmentVariable("eaddr");
		if (macaddr == NULL) {
			printf(": unable to get MAC address!\n");
			goto fail_6;
		}
		ether_aton_r(sc->sc_enaddr, sizeof(sc->sc_enaddr), macaddr);
	}

	evcnt_attach_dynamic(&sc->sq_intrcnt, EVCNT_TYPE_INTR, NULL,
	    device_xname(self), "intr");

	if ((cpu_intr_establish(haa->ha_irq, IPL_NET, sq_intr, sc)) == NULL) {
		printf(": unable to establish interrupt!\n");
		goto fail_6;
	}

	/* Reset the chip to a known state. */
	sq_reset(sc);

	/*
	 * Determine if we're an 8003 or 80c03 by setting the first
	 * MAC address register to non-zero, and then reading it back.
	 * If it's zero, we have an 80c03, because we will have read
	 * the TxCollLSB register.
	 */
	sq_seeq_write(sc, SEEQ_TXCOLLS0, 0xa5);
	if (sq_seeq_read(sc, SEEQ_TXCOLLS0) == 0)
		sc->sc_type = SQ_TYPE_80C03;
	else
		sc->sc_type = SQ_TYPE_8003;
	sq_seeq_write(sc, SEEQ_TXCOLLS0, 0x00);

	printf(": SGI Seeq %s\n",
	    sc->sc_type == SQ_TYPE_80C03 ? "80c03" : "8003");

	printf("%s: Ethernet address %s\n",
	    device_xname(self), ether_sprintf(sc->sc_enaddr));

	strcpy(ifp->if_xname, device_xname(self));
	ifp->if_softc = sc;
	ifp->if_mtu = ETHERMTU;
	ifp->if_init = sq_init;
	ifp->if_stop = sq_stop;
	ifp->if_start = sq_start;
	ifp->if_ioctl = sq_ioctl;
	ifp->if_watchdog = sq_watchdog;
	ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST;
	IFQ_SET_READY(&ifp->if_snd);

	if_attach(ifp);
	if_deferred_start_init(ifp, NULL);
	ether_ifattach(ifp, sc->sc_enaddr);

	memset(&sc->sq_trace, 0, sizeof(sc->sq_trace));
	/* Done! */
	return;

	/*
	 * Free any resources we've allocated during the failed attach
	 * attempt.  Do this in reverse order and fall through.
	 */
 fail_6:
	for (i = 0; i < SQ_NRXDESC; i++) {
		if (sc->sc_rxmbuf[i] != NULL) {
			bus_dmamap_unload(sc->sc_dmat, sc->sc_rxmap[i]);
			m_freem(sc->sc_rxmbuf[i]);
		}
	}
 fail_5:
	for (i = 0; i < SQ_NRXDESC; i++) {
		if (sc->sc_rxmap[i] != NULL)
			bus_dmamap_destroy(sc->sc_dmat, sc->sc_rxmap[i]);
	}
 fail_4:
	for (i = 0; i < SQ_NTXDESC; i++) {
		if (sc->sc_txmap[i] != NULL)
			bus_dmamap_destroy(sc->sc_dmat, sc->sc_txmap[i]);
	}
	bus_dmamap_unload(sc->sc_dmat, sc->sc_cdmap);
 fail_3:
	bus_dmamap_destroy(sc->sc_dmat, sc->sc_cdmap);
 fail_2:
	bus_dmamem_unmap(sc->sc_dmat,
	    (void *)sc->sc_control, sizeof(struct sq_control));
 fail_1:
	bus_dmamem_free(sc->sc_dmat, &sc->sc_cdseg, sc->sc_ncdseg);
 fail_0:
	return;
}

/* Set up data to get the interface up and running. */
int
sq_init(struct ifnet *ifp)
{
	int i;
	struct sq_softc *sc = ifp->if_softc;

	/* Cancel any in-progress I/O */
	sq_stop(ifp, 0);

	sc->sc_nextrx = 0;

	sc->sc_nfreetx = SQ_NTXDESC;
	sc->sc_nexttx = sc->sc_prevtx = 0;

	SQ_TRACE(SQ_RESET, sc, 0, 0);

	/* Set into 8003 mode, bank 0 to program ethernet address */
	sq_seeq_write(sc, SEEQ_TXCMD, TXCMD_BANK0);

	/* Now write the address */
	for (i = 0; i < ETHER_ADDR_LEN; i++)
		sq_seeq_write(sc, i, sc->sc_enaddr[i]);

	sc->sc_rxcmd =
	    RXCMD_IE_CRC |
	    RXCMD_IE_DRIB |
	    RXCMD_IE_SHORT |
	    RXCMD_IE_END |
	    RXCMD_IE_GOOD;

	/*
	 * Set the receive filter -- this will add some bits to the
	 * prototype RXCMD register.  Do this before setting the
	 * transmit config register, since we might need to switch
	 * banks.
	 */
	sq_set_filter(sc);

	/* Set up Seeq transmit command register */
	sq_seeq_write(sc, SEEQ_TXCMD,
	    TXCMD_IE_UFLOW |
	    TXCMD_IE_COLL |
	    TXCMD_IE_16COLL |
	    TXCMD_IE_GOOD);

	/* Now write the receive command register. */
	sq_seeq_write(sc, SEEQ_RXCMD, sc->sc_rxcmd);

	/*
	 * Set up HPC ethernet PIO and DMA configurations.
	 *
	 * The PROM appears to do most of this for the onboard HPC3, but
	 * not for the Challenge S's IOPLUS chip. We copy how the onboard
	 * chip is configured and assume that it's correct for both.
	 */
	if (sc->hpc_regs->revision == 3) {
		uint32_t dmareg, pioreg;

		pioreg =
		    HPC3_ENETR_PIOCFG_P1(1) |
		    HPC3_ENETR_PIOCFG_P2(6) |
		    HPC3_ENETR_PIOCFG_P3(1);

		dmareg =
		    HPC3_ENETR_DMACFG_D1(6) |
		    HPC3_ENETR_DMACFG_D2(2) |
		    HPC3_ENETR_DMACFG_D3(0) |
		    HPC3_ENETR_DMACFG_FIX_RXDC |
		    HPC3_ENETR_DMACFG_FIX_INTR |
		    HPC3_ENETR_DMACFG_FIX_EOP |
		    HPC3_ENETR_DMACFG_TIMEOUT;

		sq_hpc_write(sc, HPC3_ENETR_PIOCFG, pioreg);
		sq_hpc_write(sc, HPC3_ENETR_DMACFG, dmareg);
	}

	/* Pass the start of the receive ring to the HPC */
	sq_hpc_write(sc, sc->hpc_regs->enetr_ndbp, SQ_CDRXADDR(sc, 0));

	/* And turn on the HPC ethernet receive channel */
	sq_hpc_write(sc, sc->hpc_regs->enetr_ctl,
	    sc->hpc_regs->enetr_ctl_active);

	/*
	 * Turn off delayed receive interrupts on HPC1.
	 * (see Hollywood HPC Specification 2.1.4.3)
	 */
	if (sc->hpc_regs->revision != 3)
		sq_hpc_write(sc, HPC1_ENET_INTDELAY, HPC1_ENET_INTDELAY_OFF);

	ifp->if_flags |= IFF_RUNNING;

	return 0;
}

static void
sq_set_filter(struct sq_softc *sc)
{
	struct ethercom *ec = &sc->sc_ethercom;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	struct ether_multi *enm;
	struct ether_multistep step;

	/*
	 * Check for promiscuous mode.  Also implies
	 * all-multicast.
	 */
	if (ifp->if_flags & IFF_PROMISC) {
		sc->sc_rxcmd |= RXCMD_REC_ALL;
		ifp->if_flags |= IFF_ALLMULTI;
		return;
	}

	/*
	 * The 8003 has no hash table.  If we have any multicast
	 * addresses on the list, enable reception of all multicast
	 * frames.
	 *
	 * XXX The 80c03 has a hash table.  We should use it.
	 */

	ETHER_FIRST_MULTI(step, ec, enm);

	if (enm == NULL) {
		sc->sc_rxcmd &= ~RXCMD_REC_MASK;
		sc->sc_rxcmd |= RXCMD_REC_BROAD;

		ifp->if_flags &= ~IFF_ALLMULTI;
		return;
	}

	sc->sc_rxcmd |= RXCMD_REC_MULTI;
	ifp->if_flags |= IFF_ALLMULTI;
}

int
sq_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
	int s, error = 0;

	SQ_TRACE(SQ_IOCTL, (struct sq_softc *)ifp->if_softc, 0, 0);

	s = splnet();

	error = ether_ioctl(ifp, cmd, data);
	if (error == ENETRESET) {
		/*
		 * Multicast list has changed; set the hardware filter
		 * accordingly.
		 */
		if (ifp->if_flags & IFF_RUNNING)
			error = sq_init(ifp);
		else
			error = 0;
	}

	splx(s);
	return error;
}

void
sq_start(struct ifnet *ifp)
{
	struct sq_softc *sc = ifp->if_softc;
	uint32_t status;
	struct mbuf *m0, *m;
	bus_dmamap_t dmamap;
	int err, totlen, nexttx, firsttx, lasttx = -1, ofree, seg;

	if ((ifp->if_flags & IFF_RUNNING) == 0)
		return;

	/*
	 * Remember the previous number of free descriptors and
	 * the first descriptor we'll use.
	 */
	ofree = sc->sc_nfreetx;
	firsttx = sc->sc_nexttx;

	/*
	 * Loop through the send queue, setting up transmit descriptors
	 * until we drain the queue, or use up all available transmit
	 * descriptors.
	 */
	while (sc->sc_nfreetx != 0) {
		/*
		 * Grab a packet off the queue.
		 */
		IFQ_POLL(&ifp->if_snd, m0);
		if (m0 == NULL)
			break;
		m = NULL;

		dmamap = sc->sc_txmap[sc->sc_nexttx];

		/*
		 * Load the DMA map.  If this fails, the packet either
		 * didn't fit in the allotted number of segments, or we were
		 * short on resources.  In this case, we'll copy and try
		 * again.
		 * Also copy it if we need to pad, so that we are sure there
		 * is room for the pad buffer.
		 * XXX the right way of doing this is to use a static buffer
		 * for padding and adding it to the transmit descriptor (see
		 * sys/dev/pci/if_tl.c for example). We can't do this here yet
		 * because we can't send packets with more than one fragment.
		 */
		if (m0->m_pkthdr.len < ETHER_PAD_LEN ||
		    bus_dmamap_load_mbuf(sc->sc_dmat, dmamap, m0,
		    BUS_DMA_NOWAIT) != 0) {
			MGETHDR(m, M_DONTWAIT, MT_DATA);
			if (m == NULL) {
				printf("%s: unable to allocate Tx mbuf\n",
				    device_xname(sc->sc_dev));
				break;
			}
			if (m0->m_pkthdr.len > MHLEN) {
				MCLGET(m, M_DONTWAIT);
				if ((m->m_flags & M_EXT) == 0) {
					printf("%s: unable to allocate Tx "
					    "cluster\n",
					    device_xname(sc->sc_dev));
					m_freem(m);
					break;
				}
			}

			m_copydata(m0, 0, m0->m_pkthdr.len, mtod(m, void *));
			if (m0->m_pkthdr.len < ETHER_PAD_LEN) {
				memset(mtod(m, char *) + m0->m_pkthdr.len, 0,
				    ETHER_PAD_LEN - m0->m_pkthdr.len);
				m->m_pkthdr.len = m->m_len = ETHER_PAD_LEN;
			} else
				m->m_pkthdr.len = m->m_len = m0->m_pkthdr.len;

			if ((err = bus_dmamap_load_mbuf(sc->sc_dmat, dmamap,
			    m, BUS_DMA_NOWAIT)) != 0) {
				printf("%s: unable to load Tx buffer, "
				    "error = %d\n",
				    device_xname(sc->sc_dev), err);
				break;
			}
		}

		/*
		 * Ensure we have enough descriptors free to describe
		 * the packet.
		 */
		if (dmamap->dm_nsegs > sc->sc_nfreetx) {
			/*
			 * Not enough free descriptors to transmit this
			 * packet.  We haven't committed to anything yet,
			 * so just unload the DMA map, put the packet
			 * back on the queue, and punt.
			 *
			 * XXX We could allocate an mbuf and copy, but
			 * XXX it is worth it?
			 */
			bus_dmamap_unload(sc->sc_dmat, dmamap);
			m_freem(m);
			break;
		}

		IFQ_DEQUEUE(&ifp->if_snd, m0);
		/*
		 * Pass the packet to any BPF listeners.
		 */
		bpf_mtap(ifp, m0, BPF_D_OUT);
		if (m != NULL) {
			m_freem(m0);
			m0 = m;
		}

		/*
		 * WE ARE NOW COMMITTED TO TRANSMITTING THE PACKET.
		 */

		SQ_TRACE(SQ_ENQUEUE, sc, sc->sc_nexttx, 0);

		/* Sync the DMA map. */
		bus_dmamap_sync(sc->sc_dmat, dmamap, 0, dmamap->dm_mapsize,
		    BUS_DMASYNC_PREWRITE);

		/*
		 * Initialize the transmit descriptors.
		 */
		for (nexttx = sc->sc_nexttx, seg = 0, totlen = 0;
		     seg < dmamap->dm_nsegs;
		     seg++, nexttx = SQ_NEXTTX(nexttx)) {
			if (sc->hpc_regs->revision == 3) {
				sc->sc_txdesc[nexttx].hpc3_hdd_bufptr =
				    dmamap->dm_segs[seg].ds_addr;
				sc->sc_txdesc[nexttx].hpc3_hdd_ctl =
				    dmamap->dm_segs[seg].ds_len;
			} else {
				sc->sc_txdesc[nexttx].hpc1_hdd_bufptr =
				    dmamap->dm_segs[seg].ds_addr;
				sc->sc_txdesc[nexttx].hpc1_hdd_ctl =
				    dmamap->dm_segs[seg].ds_len;
			}
			sc->sc_txdesc[nexttx].hdd_descptr =
			    SQ_CDTXADDR(sc, SQ_NEXTTX(nexttx));
			lasttx = nexttx;
			totlen += dmamap->dm_segs[seg].ds_len;
		}

		/* Last descriptor gets end-of-packet */
		KASSERT(lasttx != -1);
		if (sc->hpc_regs->revision == 3)
			sc->sc_txdesc[lasttx].hpc3_hdd_ctl |=
			    HPC3_HDD_CTL_EOPACKET;
		else
			sc->sc_txdesc[lasttx].hpc1_hdd_ctl |=
			    HPC1_HDD_CTL_EOPACKET;

		SQ_DPRINTF(("%s: transmit %d-%d, len %d\n",
		    device_xname(sc->sc_dev), sc->sc_nexttx, lasttx, totlen));

		if (ifp->if_flags & IFF_DEBUG) {
			printf("     transmit chain:\n");
			for (seg = sc->sc_nexttx;; seg = SQ_NEXTTX(seg)) {
				printf("     descriptor %d:\n", seg);
				printf("       hdd_bufptr:      0x%08x\n",
				    (sc->hpc_regs->revision == 3) ?
				    sc->sc_txdesc[seg].hpc3_hdd_bufptr :
				    sc->sc_txdesc[seg].hpc1_hdd_bufptr);
				printf("       hdd_ctl: 0x%08x\n",
				    (sc->hpc_regs->revision == 3) ?
				    sc->sc_txdesc[seg].hpc3_hdd_ctl:
				    sc->sc_txdesc[seg].hpc1_hdd_ctl);
				printf("       hdd_descptr:      0x%08x\n",
				    sc->sc_txdesc[seg].hdd_descptr);

				if (seg == lasttx)
					break;
			}
		}

		/* Sync the descriptors we're using. */
		SQ_CDTXSYNC(sc, sc->sc_nexttx, dmamap->dm_nsegs,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

		/* Store a pointer to the packet so we can free it later */
		sc->sc_txmbuf[sc->sc_nexttx] = m0;

		/* Advance the tx pointer. */
		sc->sc_nfreetx -= dmamap->dm_nsegs;
		sc->sc_nexttx = nexttx;
	}

	if (sc->sc_nfreetx != ofree) {
		SQ_DPRINTF(("%s: %d packets enqueued, first %d, INTR on %d\n",
		    device_xname(sc->sc_dev), lasttx - firsttx + 1,
		    firsttx, lasttx));

		/*
		 * Cause a transmit interrupt to happen on the
		 * last packet we enqueued, mark it as the last
		 * descriptor.
		 *
		 * HPC1_HDD_CTL_INTR will generate an interrupt on
		 * HPC1. HPC3 requires HPC3_HDD_CTL_EOPACKET in
		 * addition to HPC3_HDD_CTL_INTR to interrupt.
		 */
		KASSERT(lasttx != -1);
		if (sc->hpc_regs->revision == 3) {
			sc->sc_txdesc[lasttx].hpc3_hdd_ctl |=
			    HPC3_HDD_CTL_INTR | HPC3_HDD_CTL_EOCHAIN;
		} else {
			sc->sc_txdesc[lasttx].hpc1_hdd_ctl |= HPC1_HDD_CTL_INTR;
			sc->sc_txdesc[lasttx].hpc1_hdd_bufptr |=
			    HPC1_HDD_CTL_EOCHAIN;
		}

		SQ_CDTXSYNC(sc, lasttx, 1,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

		/*
		 * There is a potential race condition here if the HPC
		 * DMA channel is active and we try and either update
		 * the 'next descriptor' pointer in the HPC PIO space
		 * or the 'next descriptor' pointer in a previous desc-
		 * riptor.
		 *
		 * To avoid this, if the channel is active, we rely on
		 * the transmit interrupt routine noticing that there
		 * are more packets to send and restarting the HPC DMA
		 * engine, rather than mucking with the DMA state here.
		 */
		status = sq_hpc_read(sc, sc->hpc_regs->enetx_ctl);

		if ((status & sc->hpc_regs->enetx_ctl_active) != 0) {
			SQ_TRACE(SQ_ADD_TO_DMA, sc, firsttx, status);

			/*
			 * NB: hpc3_hdd_ctl == hpc1_hdd_bufptr, and
			 * HPC1_HDD_CTL_EOCHAIN == HPC3_HDD_CTL_EOCHAIN
			 */
			sc->sc_txdesc[SQ_PREVTX(firsttx)].hpc3_hdd_ctl &=
			    ~HPC3_HDD_CTL_EOCHAIN;

			if (sc->hpc_regs->revision != 3)
				sc->sc_txdesc[SQ_PREVTX(firsttx)].hpc1_hdd_ctl
				    &= ~HPC1_HDD_CTL_INTR;

			SQ_CDTXSYNC(sc, SQ_PREVTX(firsttx),  1,
			    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
		} else if (sc->hpc_regs->revision == 3) {
			SQ_TRACE(SQ_START_DMA, sc, firsttx, status);

			sq_hpc_write(sc, HPC3_ENETX_NDBP, SQ_CDTXADDR(sc,
			    firsttx));

			/* Kick DMA channel into life */
			sq_hpc_write(sc, HPC3_ENETX_CTL, HPC3_ENETX_CTL_ACTIVE);
		} else {
			/*
			 * In the HPC1 case where transmit DMA is
			 * inactive, we can either kick off if
			 * the ring was previously empty, or call
			 * our transmit interrupt handler to
			 * figure out if the ring stopped short
			 * and restart at the right place.
			 */
			if (ofree == SQ_NTXDESC) {
				SQ_TRACE(SQ_START_DMA, sc, firsttx, status);

				sq_hpc_write(sc, HPC1_ENETX_NDBP,
				    SQ_CDTXADDR(sc, firsttx));
				sq_hpc_write(sc, HPC1_ENETX_CFXBP,
				    SQ_CDTXADDR(sc, firsttx));
				sq_hpc_write(sc, HPC1_ENETX_CBP,
				    SQ_CDTXADDR(sc, firsttx));

				/* Kick DMA channel into life */
				sq_hpc_write(sc, HPC1_ENETX_CTL,
				    HPC1_ENETX_CTL_ACTIVE);
			} else
				sq_txring_hpc1(sc);
		}

		/* Set a watchdog timer in case the chip flakes out. */
		ifp->if_timer = 5;
	}
}

void
sq_stop(struct ifnet *ifp, int disable)
{
	int i;
	struct sq_softc *sc = ifp->if_softc;

	for (i = 0; i < SQ_NTXDESC; i++) {
		if (sc->sc_txmbuf[i] != NULL) {
			bus_dmamap_unload(sc->sc_dmat, sc->sc_txmap[i]);
			m_freem(sc->sc_txmbuf[i]);
			sc->sc_txmbuf[i] = NULL;
		}
	}

	/* Clear Seeq transmit/receive command registers */
	sq_seeq_write(sc, SEEQ_TXCMD, 0);
	sq_seeq_write(sc, SEEQ_RXCMD, 0);

	sq_reset(sc);

	ifp->if_flags &= ~IFF_RUNNING;
	ifp->if_timer = 0;
}

/* Device timeout/watchdog routine. */
void
sq_watchdog(struct ifnet *ifp)
{
	uint32_t status;
	struct sq_softc *sc = ifp->if_softc;

	status = sq_hpc_read(sc, sc->hpc_regs->enetx_ctl);
	log(LOG_ERR, "%s: device timeout (prev %d, next %d, free %d, "
	    "status %08x)\n", device_xname(sc->sc_dev), sc->sc_prevtx,
	    sc->sc_nexttx, sc->sc_nfreetx, status);

	sq_trace_dump(sc);

	memset(&sc->sq_trace, 0, sizeof(sc->sq_trace));
	sc->sq_trace_idx = 0;

	if_statinc(ifp, if_oerrors);

	sq_init(ifp);
}

static void
sq_trace_dump(struct sq_softc *sc)
{
	int i;
	const char *act;

	for (i = 0; i < sc->sq_trace_idx; i++) {
		switch (sc->sq_trace[i].action) {
		case SQ_RESET:		act = "SQ_RESET";		break;
		case SQ_ADD_TO_DMA:	act = "SQ_ADD_TO_DMA";		break;
		case SQ_START_DMA:	act = "SQ_START_DMA";		break;
		case SQ_DONE_DMA:	act = "SQ_DONE_DMA";		break;
		case SQ_RESTART_DMA:	act = "SQ_RESTART_DMA";		break;
		case SQ_TXINTR_ENTER:	act = "SQ_TXINTR_ENTER";	break;
		case SQ_TXINTR_EXIT:	act = "SQ_TXINTR_EXIT";		break;
		case SQ_TXINTR_BUSY:	act = "SQ_TXINTR_BUSY";		break;
		case SQ_IOCTL:		act = "SQ_IOCTL";		break;
		case SQ_ENQUEUE:	act = "SQ_ENQUEUE";		break;
		default:		act = "UNKNOWN";
		}

		printf("%s: [%03d] action %-16s buf %03d free %03d "
		    "status %08x line %d\n", device_xname(sc->sc_dev), i, act,
		    sc->sq_trace[i].bufno, sc->sq_trace[i].freebuf,
		    sc->sq_trace[i].status, sc->sq_trace[i].line);
	}
}

static int
sq_intr(void *arg)
{
	struct sq_softc *sc = arg;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	int handled = 0;
	uint32_t stat;

	stat = sq_hpc_read(sc, sc->hpc_regs->enetr_reset);

	if ((stat & 2) == 0) {
		SQ_DPRINTF(("%s: Unexpected interrupt!\n",
		    device_xname(sc->sc_dev)));
	} else
		sq_hpc_write(sc, sc->hpc_regs->enetr_reset, (stat | 2));

	/*
	 * If the interface isn't running, the interrupt couldn't
	 * possibly have come from us.
	 */
	if ((ifp->if_flags & IFF_RUNNING) == 0)
		return 0;

	sc->sq_intrcnt.ev_count++;

	/* Always check for received packets */
	if (sq_rxintr(sc) != 0)
		handled++;

	/* Only handle transmit interrupts if we actually sent something */
	if (sc->sc_nfreetx < SQ_NTXDESC) {
		sq_txintr(sc);
		handled++;
	}

	if (handled)
		rnd_add_uint32(&sc->rnd_source, stat);
	return handled;
}

static int
sq_rxintr(struct sq_softc *sc)
{
	int count = 0;
	struct mbuf* m;
	int i, framelen;
	uint8_t pktstat;
	uint32_t status;
	uint32_t ctl_reg;
	int new_end, orig_end;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;

	for (i = sc->sc_nextrx;; i = SQ_NEXTRX(i)) {
		SQ_CDRXSYNC(sc, i,
		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

		/*
		 * If this is a CPU-owned buffer, we're at the end of the list.
		 */
		if (sc->hpc_regs->revision == 3)
			ctl_reg =
			    sc->sc_rxdesc[i].hpc3_hdd_ctl & HPC3_HDD_CTL_OWN;
		else
			ctl_reg =
			    sc->sc_rxdesc[i].hpc1_hdd_ctl & HPC1_HDD_CTL_OWN;

		if (ctl_reg) {
#if defined(SQ_DEBUG)
			uint32_t reg;

			reg = sq_hpc_read(sc, sc->hpc_regs->enetr_ctl);
			SQ_DPRINTF(("%s: rxintr: done at %d (ctl %08x)\n",
			    device_xname(sc->sc_dev), i, reg));
#endif
			break;
		}

		count++;

		m = sc->sc_rxmbuf[i];
		framelen = m->m_ext.ext_size - 3;
		if (sc->hpc_regs->revision == 3)
		    framelen -=
			HPC3_HDD_CTL_BYTECNT(sc->sc_rxdesc[i].hpc3_hdd_ctl);
		else
		    framelen -=
			HPC1_HDD_CTL_BYTECNT(sc->sc_rxdesc[i].hpc1_hdd_ctl);

		/* Now sync the actual packet data */
		bus_dmamap_sync(sc->sc_dmat, sc->sc_rxmap[i], 0,
		    sc->sc_rxmap[i]->dm_mapsize, BUS_DMASYNC_POSTREAD);

		pktstat = *((uint8_t *)m->m_data + framelen + 2);

		if ((pktstat & RXSTAT_GOOD) == 0) {
			if_statinc(ifp, if_ierrors);

			if (pktstat & RXSTAT_OFLOW)
				printf("%s: receive FIFO overflow\n",
				    device_xname(sc->sc_dev));

			bus_dmamap_sync(sc->sc_dmat, sc->sc_rxmap[i], 0,
			    sc->sc_rxmap[i]->dm_mapsize, BUS_DMASYNC_PREREAD);
			SQ_INIT_RXDESC(sc, i);
			SQ_DPRINTF(("%s: sq_rxintr: buf %d no RXSTAT_GOOD\n",
			    device_xname(sc->sc_dev), i));
			continue;
		}

		if (sq_add_rxbuf(sc, i) != 0) {
			if_statinc(ifp, if_ierrors);
			bus_dmamap_sync(sc->sc_dmat, sc->sc_rxmap[i], 0,
			    sc->sc_rxmap[i]->dm_mapsize, BUS_DMASYNC_PREREAD);
			SQ_INIT_RXDESC(sc, i);
			SQ_DPRINTF(("%s: sq_rxintr: buf %d sq_add_rxbuf() "
			    "failed\n", device_xname(sc->sc_dev), i));
			continue;
		}


		m->m_data += 2;
		m_set_rcvif(m, ifp);
		m->m_pkthdr.len = m->m_len = framelen;

		SQ_DPRINTF(("%s: sq_rxintr: buf %d len %d\n",
		    device_xname(sc->sc_dev), i, framelen));

		if_percpuq_enqueue(ifp->if_percpuq, m);
	}


	/* If anything happened, move ring start/end pointers to new spot */
	if (i != sc->sc_nextrx) {
		/*
		 * NB: hpc3_hdd_ctl == hpc1_hdd_bufptr, and
		 * HPC1_HDD_CTL_EOCHAIN == HPC3_HDD_CTL_EOCHAIN
		 */

		new_end = SQ_PREVRX(i);
		sc->sc_rxdesc[new_end].hpc3_hdd_ctl |= HPC3_HDD_CTL_EOCHAIN;
		SQ_CDRXSYNC(sc, new_end,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

		orig_end = SQ_PREVRX(sc->sc_nextrx);
		sc->sc_rxdesc[orig_end].hpc3_hdd_ctl &= ~HPC3_HDD_CTL_EOCHAIN;
		SQ_CDRXSYNC(sc, orig_end,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

		sc->sc_nextrx = i;
	}

	status = sq_hpc_read(sc, sc->hpc_regs->enetr_ctl);

	/* If receive channel is stopped, restart it... */
	if ((status & sc->hpc_regs->enetr_ctl_active) == 0) {
		/* Pass the start of the receive ring to the HPC */
		sq_hpc_write(sc, sc->hpc_regs->enetr_ndbp,
		    SQ_CDRXADDR(sc, sc->sc_nextrx));

		/* And turn on the HPC ethernet receive channel */
		sq_hpc_write(sc, sc->hpc_regs->enetr_ctl,
		    sc->hpc_regs->enetr_ctl_active);
	}

	return count;
}

static int
sq_txintr(struct sq_softc *sc)
{
	int shift = 0;
	uint32_t status, tmp;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;

	if (sc->hpc_regs->revision != 3)
		shift = 16;

	status = sq_hpc_read(sc, sc->hpc_regs->enetx_ctl) >> shift;

	SQ_TRACE(SQ_TXINTR_ENTER, sc, sc->sc_prevtx, status);

	net_stat_ref_t nsr = IF_STAT_GETREF(ifp);
	tmp = (sc->hpc_regs->enetx_ctl_active >> shift) | TXSTAT_GOOD;
	if ((status & tmp) == 0) {
		if (status & TXSTAT_COLL)
			if_statinc_ref(ifp, nsr, if_collisions);

		if (status & TXSTAT_UFLOW) {
			printf("%s: transmit underflow\n",
			    device_xname(sc->sc_dev));
			if_statinc_ref(ifp, nsr, if_oerrors);
		}

		if (status & TXSTAT_16COLL) {
			printf("%s: max collisions reached\n",
			    device_xname(sc->sc_dev));
			if_statinc_ref(ifp, nsr, if_oerrors);
			if_statadd_ref(ifp, nsr, if_collisions, 16);
		}
	}
	IF_STAT_PUTREF(ifp);

	/* prevtx now points to next xmit packet not yet finished */
	if (sc->hpc_regs->revision == 3)
		sq_txring_hpc3(sc);
	else
		sq_txring_hpc1(sc);

	/* If all packets have left the coop, cancel watchdog */
	if (sc->sc_nfreetx == SQ_NTXDESC)
		ifp->if_timer = 0;

	SQ_TRACE(SQ_TXINTR_EXIT, sc, sc->sc_prevtx, status);
	if_schedule_deferred_start(ifp);

	return 1;
}

/*
 * Reclaim used transmit descriptors and restart the transmit DMA
 * engine if necessary.
 */
static void
sq_txring_hpc1(struct sq_softc *sc)
{
	/*
	 * HPC1 doesn't tag transmitted descriptors, however,
	 * the NDBP register points to the next descriptor that
	 * has not yet been processed. If DMA is not in progress,
	 * we can safely reclaim all descriptors up to NDBP, and,
	 * if necessary, restart DMA at NDBP. Otherwise, if DMA
	 * is active, we can only safely reclaim up to CBP.
	 *
	 * For now, we'll only reclaim on inactive DMA and assume
	 * that a sufficiently large ring keeps us out of trouble.
	 */
	uint32_t reclaimto, status;
	int reclaimall, i = sc->sc_prevtx;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;

	status = sq_hpc_read(sc, HPC1_ENETX_CTL);
	if (status & HPC1_ENETX_CTL_ACTIVE) {
		SQ_TRACE(SQ_TXINTR_BUSY, sc, i, status);
		return;
	} else
		reclaimto = sq_hpc_read(sc, HPC1_ENETX_NDBP);

	if (sc->sc_nfreetx == 0 && SQ_CDTXADDR(sc, i) == reclaimto)
		reclaimall = 1;
	else
		reclaimall = 0;

	while (sc->sc_nfreetx < SQ_NTXDESC) {
		if (SQ_CDTXADDR(sc, i) == reclaimto && !reclaimall)
			break;

		SQ_CDTXSYNC(sc, i, sc->sc_txmap[i]->dm_nsegs,
		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

		/* Sync the packet data, unload DMA map, free mbuf */
		bus_dmamap_sync(sc->sc_dmat, sc->sc_txmap[i],
		    0, sc->sc_txmap[i]->dm_mapsize, BUS_DMASYNC_POSTWRITE);
		bus_dmamap_unload(sc->sc_dmat, sc->sc_txmap[i]);
		m_freem(sc->sc_txmbuf[i]);
		sc->sc_txmbuf[i] = NULL;

		if_statinc(ifp, if_opackets);
		sc->sc_nfreetx++;

		SQ_TRACE(SQ_DONE_DMA, sc, i, status);

		i = SQ_NEXTTX(i);
	}

	if (sc->sc_nfreetx < SQ_NTXDESC) {
		SQ_TRACE(SQ_RESTART_DMA, sc, i, status);

		KASSERT(reclaimto == SQ_CDTXADDR(sc, i));

		sq_hpc_write(sc, HPC1_ENETX_CFXBP, reclaimto);
		sq_hpc_write(sc, HPC1_ENETX_CBP, reclaimto);

		/* Kick DMA channel into life */
		sq_hpc_write(sc, HPC1_ENETX_CTL, HPC1_ENETX_CTL_ACTIVE);

		/*
		 * Set a watchdog timer in case the chip
		 * flakes out.
		 */
		ifp->if_timer = 5;
	}

	sc->sc_prevtx = i;
}

/*
 * Reclaim used transmit descriptors and restart the transmit DMA
 * engine if necessary.
 */
static void
sq_txring_hpc3(struct sq_softc *sc)
{
	/*
	 * HPC3 tags descriptors with a bit once they've been
	 * transmitted. We need only free each XMITDONE'd
	 * descriptor, and restart the DMA engine if any
	 * descriptors are left over.
	 */
	int i;
	uint32_t status = 0;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;

	i = sc->sc_prevtx;
	while (sc->sc_nfreetx < SQ_NTXDESC) {
		/*
		 * Check status first so we don't end up with a case of
		 * the buffer not being finished while the DMA channel
		 * has gone idle.
		 */
		status = sq_hpc_read(sc, HPC3_ENETX_CTL);

		SQ_CDTXSYNC(sc, i, sc->sc_txmap[i]->dm_nsegs,
		    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

		/* Check for used descriptor and restart DMA chain if needed */
		if ((sc->sc_txdesc[i].hpc3_hdd_ctl &
		    HPC3_HDD_CTL_XMITDONE) == 0) {
			if ((status & HPC3_ENETX_CTL_ACTIVE) == 0) {
				SQ_TRACE(SQ_RESTART_DMA, sc, i, status);

				sq_hpc_write(sc, HPC3_ENETX_NDBP,
				    SQ_CDTXADDR(sc, i));

				/* Kick DMA channel into life */
				sq_hpc_write(sc, HPC3_ENETX_CTL,
				    HPC3_ENETX_CTL_ACTIVE);

				/*
				 * Set a watchdog timer in case the chip
				 * flakes out.
				 */
				ifp->if_timer = 5;
			} else
				SQ_TRACE(SQ_TXINTR_BUSY, sc, i, status);
			break;
		}

		/* Sync the packet data, unload DMA map, free mbuf */
		bus_dmamap_sync(sc->sc_dmat, sc->sc_txmap[i],
		    0, sc->sc_txmap[i]->dm_mapsize, BUS_DMASYNC_POSTWRITE);
		bus_dmamap_unload(sc->sc_dmat, sc->sc_txmap[i]);
		m_freem(sc->sc_txmbuf[i]);
		sc->sc_txmbuf[i] = NULL;

		if_statinc(ifp, if_opackets);
		sc->sc_nfreetx++;

		SQ_TRACE(SQ_DONE_DMA, sc, i, status);
		i = SQ_NEXTTX(i);
	}

	sc->sc_prevtx = i;
}

void
sq_reset(struct sq_softc *sc)
{

	/* Stop HPC dma channels */
	sq_hpc_write(sc, sc->hpc_regs->enetr_ctl, 0);
	sq_hpc_write(sc, sc->hpc_regs->enetx_ctl, 0);

	sq_hpc_write(sc, sc->hpc_regs->enetr_reset, 3);
	delay(20);
	sq_hpc_write(sc, sc->hpc_regs->enetr_reset, 0);
}

/* sq_add_rxbuf: Add a receive buffer to the indicated descriptor. */
int
sq_add_rxbuf(struct sq_softc *sc, int idx)
{
	int err;
	struct mbuf *m;

	MGETHDR(m, M_DONTWAIT, MT_DATA);
	if (m == NULL)
		return ENOBUFS;

	MCLGET(m, M_DONTWAIT);
	if ((m->m_flags & M_EXT) == 0) {
		m_freem(m);
		return ENOBUFS;
	}

	if (sc->sc_rxmbuf[idx] != NULL)
		bus_dmamap_unload(sc->sc_dmat, sc->sc_rxmap[idx]);

	sc->sc_rxmbuf[idx] = m;

	if ((err = bus_dmamap_load(sc->sc_dmat, sc->sc_rxmap[idx],
	    m->m_ext.ext_buf, m->m_ext.ext_size, NULL, BUS_DMA_NOWAIT)) != 0) {
		printf("%s: can't load rx DMA map %d, error = %d\n",
		    device_xname(sc->sc_dev), idx, err);
		panic("sq_add_rxbuf");	/* XXX */
	}

	bus_dmamap_sync(sc->sc_dmat, sc->sc_rxmap[idx],
	    0, sc->sc_rxmap[idx]->dm_mapsize, BUS_DMASYNC_PREREAD);

	SQ_INIT_RXDESC(sc, idx);

	return 0;
}

void
sq_dump_buffer(paddr_t addr, psize_t len)
{
	u_int i;
	uint8_t *physaddr = (uint8_t *)MIPS_PHYS_TO_KSEG1(addr);

	if (len == 0)
		return;

	printf("%p: ", physaddr);

	for (i = 0; i < len; i++) {
		printf("%02x ", *(physaddr + i) & 0xff);
		if ((i % 16) == 15 && i != len - 1)
		    printf("\n%p: ", physaddr + i);
	}

	printf("\n");
}