This driver supports the SDL Communications RISCom/N2 ISA cards that is

based on the HD64570 chip. Both the 1 and 2 port cards is supported.

Line speeds of up to 2Mbps is possible. At this speed about 95% of the
bandwidth is usable with 486DX processors.

The standard FreeBSD sppp code is used for the link level layer. The
default protocol used is PPP. The Cisco HDLC protocol can be used by
adding "link2" to the ifconfig line in /etc/sysconfig or where ever
ifconfig is run.

At the moment only the X.21 interface is tested. The others may need
tweaks to the clock selection code.

1 files changed, 1697 insertions, 0 deletions

diff --git a/sys/dev/sr/if_sr_isa.c b/sys/dev/sr/if_sr_isa.c
new file mode 100644
index 0000000..bf1cdd1
--- /dev/null
+++ b/sys/dev/sr/if_sr_isa.c
@@ -0,0 +1,1697 @@
+/*
+ * Copyright (c) 1996 John Hay.  All rights reserved.
+ *
+ * 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. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by John Hay.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY John Hay ``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 John Hay 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.
+ *
+ * $Id$
+ */
+
+/*
+ * Programming assumptions and other issues.
+ *
+ * Only a 16K window will be used.
+ *
+ * The descriptors of a DMA channel will fit in a 16K memory window.
+ *
+ * The buffers of a transmit DMA channel will fit in a 16K memory window.
+ *
+ * When interface is going up, handshaking is set and it is only cleared
+ * when the interface is down'ed.
+ *
+ * There should be a way to set/reset Raw HDLC/PPP, Loopback, DCE/DTE,
+ * internal/external clock, etc.....
+ *
+ */
+
+#include "sr.h"
+#include "bpfilter.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/mbuf.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/conf.h>
+#include <sys/errno.h>
+#include <sys/malloc.h>
+
+#include <sys/syslog.h>
+#include <net/if.h>
+#include <net/if_types.h>
+#include <net/if_sppp.h>
+
+#if NBPFILTER > 0
+#include <net/bpf.h>
+#include <net/bpfdesc.h>
+#endif
+
+#include <sys/devconf.h>
+#include <machine/clock.h>
+#include <machine/md_var.h>
+
+#include <i386/isa/if_srregs.h>
+#include <i386/isa/ic/hd64570.h>
+
+#ifdef TRACE
+#define TRC(x)               x
+#else
+#define TRC(x)
+#endif
+
+#define TRCL(x)              x
+
+#define PPP_HEADER_LEN       4
+
+#define SRC_REG(iobase,y)	((y & 0xf) + ((y & 0xf0) << 6) + \
+					iobase | 0x8000)
+
+#define SRC_GET8(iobase,off)	inb(SRC_REG(iobase,(u_int)&off))
+#define SRC_GET16(iobase,off)	inw(SRC_REG(iobase,(u_int)&off))
+#define SRC_PUT8(iobase,off,d)	outb(SRC_REG(iobase,(u_int)&off),d)
+#define SRC_PUT16(iobase,off,d)	outw(SRC_REG(iobase,(u_int)&off),d)
+
+#define SRC_GET_WIN(addr)	((addr >> SRC_WIN_SHFT) & SR_PG_MSK)
+
+#define SRC_SET_ON(iobase)	outb(iobase+SR_PCR, \
+					SR_PCR_MEM_WIN | inb(iobase+SR_PCR))
+#define SRC_SET_MEM(iobase,win)	outb(iobase+SR_PSR, SRC_GET_WIN(win) | \
+					inb(iobase+SR_PSR) & ~SR_PG_MSK)
+#define SRC_SET_OFF(iobase)	outb(iobase+SR_PCR, \
+					~SR_PCR_MEM_WIN & inb(iobase+SR_PCR))
+
+static struct sr_hardc {
+	int cunit;
+	struct sr_softc *sc;
+	u_short iobase;
+	int startunit;
+	int numports;
+	caddr_t mem_start;
+	caddr_t mem_end;
+
+	u_int memsize;		/* in bytes */
+
+	sca_regs *sca;
+
+	struct kern_devconf kdc;
+}sr_hardc[NSR];
+
+struct sr_softc {
+	struct sppp ifsppp;
+	int unit;            /* With regards to all sr devices */
+	int subunit;         /* With regards to this card */
+	struct sr_hardc *hc;
+
+	struct buf_block {
+		u_int txdesc;        /* On card address */
+		u_int txstart;       /* On card address */
+		u_int txend;         /* On card address */
+		u_int txtail;        /* Index of first unused buffer */
+		u_int txmax;         /* number of usable buffers/descriptors */
+		u_int txeda;         /* Error descriptor addresses */
+	}block[SR_TX_BLOCKS];
+
+	char  xmit_busy;     /* Transmitter is busy */
+	char  txb_inuse;     /* Number of tx blocks currently in use */
+	char  txb_new;       /* Index to where new buffer will be added */
+	char  txb_next_tx;    /* Index to next block ready to tx */
+
+	u_int rxdesc;        /* On card address */
+	u_int rxstart;       /* On card address */
+	u_int rxend;         /* On card address */
+	u_int rxhind;        /* Index to the head of the rx buffers. */
+	u_int rxmax;         /* number of usable buffers/descriptors */
+
+	u_int clk_cfg;       /* Clock configuration */
+
+	int scachan;
+
+	struct kern_devconf kdc;
+};
+
+static int srprobe(struct isa_device *id);
+static int srattach(struct isa_device *id);
+
+/*
+ * List of valid interrupt numbers.
+ */
+static int sr_irqtable[16] = {
+	0,	/*  0 */
+	0,	/*  1 */
+	0,	/*  2 */
+	1,	/*  3 */
+	1,	/*  4 */
+	1,	/*  5 */
+	0,	/*  6 */
+	1,	/*  7 */
+	0,	/*  8 */
+	0,	/*  9 */
+	1,	/* 10 */
+	1,	/* 11 */
+	1,	/* 12 */
+	0,	/* 13 */
+	0,	/* 14 */
+	1	/* 15 */
+};
+
+struct isa_driver srdriver = {srprobe, srattach, "src"};
+
+static struct kern_devconf kdc_sr_template = { 
+	0, 0, 0, 
+	"sr", 0, { MDDT_ISA, 0, "net" },
+	isa_generic_externalize, 0, 0, ISA_EXTERNALLEN, 
+	&kdc_isa0, 
+	0,
+	DC_UNCONFIGURED, 
+	"SDL Riscom/N2 Port",
+	DC_CLS_NETIF
+};
+
+static struct kern_devconf kdc_src_template = { 
+	0, 0, 0, 
+	"src", 0, { MDDT_ISA, 0, "net" },
+	isa_generic_externalize, 0, 0, ISA_EXTERNALLEN, 
+	&kdc_isa0, 
+	0,
+	DC_UNCONFIGURED, 
+	"SDL Riscom/N2 Adapter",
+	DC_CLS_NETIF
+};
+
+static void sr_xmit(struct sr_softc *sc);
+static void srstart(struct ifnet *ifp);
+static int srioctl(struct ifnet *ifp, int cmd, caddr_t data);
+static void srwatchdog(struct ifnet *ifp);
+static int sr_packet_avail(struct sr_softc *sc, int *len, u_char *rxstat);
+static void sr_copy_rxbuf(struct mbuf *m, struct sr_softc *sc, int len);
+static void sr_eat_packet(struct sr_softc *sc, int single);
+static void sr_get_packets(struct sr_softc *sc);
+
+static void sr_up(struct sr_softc *sc);
+static void sr_down(struct sr_softc *sc);
+static void src_init(struct isa_device *id);
+static void sr_init_sca(struct sr_hardc *hc);
+static void sr_init_msci(struct sr_softc *sc);
+static void sr_init_rx_dmac(struct sr_softc *sc);
+static void sr_init_tx_dmac(struct sr_softc *sc);
+static void sr_dmac_intr(struct sr_hardc *hc, u_char isr);
+static void sr_msci_intr(struct sr_hardc *hc, u_char isr);
+static void sr_timer_intr(struct sr_hardc *hc, u_char isr);
+
+static inline void
+sr_registerdev(int ctlr, int unit)
+{
+	struct sr_softc *sc;
+	
+	sc = &sr_hardc[ctlr].sc[unit];
+	sc->kdc = kdc_sr_template;
+
+	sc->kdc.kdc_unit = sr_hardc[ctlr].startunit + unit;
+	sc->kdc.kdc_parentdata = &sr_hardc[ctlr].kdc;
+	dev_attach(&sc->kdc);
+}
+
+static inline void
+src_registerdev(struct isa_device *dvp)
+{
+        int unit = dvp->id_unit;
+	struct sr_hardc *hc = &sr_hardc[dvp->id_unit];
+
+	hc->kdc = kdc_src_template;
+
+        hc->kdc.kdc_unit = unit;
+        hc->kdc.kdc_parentdata = dvp;
+        dev_attach(&hc->kdc);
+}
+
+
+/*
+ * Register the Adapter.
+ * Probe to see if it is there.
+ * Get its information and fill it in.
+ */
+static int
+srprobe(struct isa_device *id)
+{
+	struct sr_hardc *hc = &sr_hardc[id->id_unit];
+	u_int pgs, i, tmp;
+	u_short port;
+	u_short *smem;
+	u_char mar;
+	sca_regs *sca = 0;
+
+	/*
+	 * Register the card.
+	 */
+	src_registerdev(id);
+
+	/*
+	 * Now see if the card is realy there.
+	 *
+	 * If it is there, size its memory.
+	 */
+	hc->sca = 0;
+	port = id->id_iobase;
+	hc->memsize = 64 * 1024;
+	hc->numports = NCHAN;
+	if(id->id_flags & SR_FLAGS_NCHAN_MSK)
+		hc->numports = id->id_flags & SR_FLAGS_NCHAN_MSK;
+
+	outb(port + SR_PCR, 0);
+	for(i=0;i<0x100;i++) {
+		outb(port + SR_BAR, i);
+		inb(port + SR_PCR);
+		tmp = inb(port + SR_BAR);
+		if(tmp != i) {
+			printf("sr%d: probe failed BAR %x, %x.\n",
+				id->id_unit,
+				i,
+				tmp);
+			return 0;
+		}
+	}
+
+	/*
+	 * Now see if its memory also works.
+	 */
+	outb(port + SR_PCR, SR_PCR_EN_VPM |
+				  SR_PCR_ISA16);
+	outb(port + SR_PSR, SR_PSR_WIN_16K);
+
+	mar = (kvtop(id->id_maddr) >> 16) & SR_PCR_16M_SEL;
+	outb(port + SR_PCR, mar | inb(port + SR_PCR));
+	mar = kvtop(id->id_maddr) >> 12;
+	outb(port + SR_BAR, mar);
+
+	outb(port + SR_PCR, inb(port + SR_PCR) | SR_PCR_MEM_WIN);
+
+	smem = (u_short *)id->id_maddr;
+
+	for(i=0;i<=SR_PSR_PG_SEL;i++) {
+		outb(port + SR_PSR,
+			(inb(port + SR_PSR) & ~SR_PSR_PG_SEL) | i);
+		*smem = 0xAA55;
+	}
+
+	for(i=0;i<=SR_PSR_PG_SEL;i++) {
+		outb(port + SR_PSR,
+			(inb(port + SR_PSR) & ~SR_PSR_PG_SEL) | i);
+		if(*smem != 0xAA55) {
+			/*
+			 * If we have less than 64k of memory, give up.
+			 * That is 4 x 16k pages.
+			 */
+			if(i<4) {
+				printf("sr%d: Bad mem page %d, mem %x, %x.\n",
+					id->id_unit,
+					i,
+					0xAA55,
+					*smem);
+				return 0;
+			}
+			break;
+		}
+		*smem = i;
+	}
+
+	hc->memsize = i * SRC_WIN_SIZ;
+	pgs = i;
+	for(i=0;i<=pgs;i++) {
+		outb(port + SR_PSR,
+			(inb(port + SR_PSR) & ~SR_PSR_PG_SEL) | i);
+		bzero(smem, SRC_WIN_SIZ);
+	}
+
+	/*
+	 * Now see if we can see the SCA.
+	 */
+	outb(port + SR_PCR, SR_PCR_SCARUN | inb(port + SR_PCR));
+	SRC_PUT8(port, sca->wcrl, 0);
+	SRC_PUT8(port, sca->wcrm, 0);
+	SRC_PUT8(port, sca->wcrh, 0);
+	SRC_PUT8(port, sca->pcr, 0);
+
+	SRC_PUT8(port, sca->msci[0].tmc, 0);
+	inb(port);
+	tmp = SRC_GET8(port, sca->msci[0].tmc);
+	if(tmp != 0) {
+		printf("sr%d: Error reading SCA 0, %x\n", id->id_unit, tmp);
+		return 0;
+	}
+	SRC_PUT8(port, sca->msci[0].tmc, 0x5A);
+	inb(port);
+	tmp = SRC_GET8(port, sca->msci[0].tmc);
+	if(tmp != 0x5A) {
+		printf("sr%d: Error reading SCA 0x5A, %x\n", id->id_unit, tmp);
+		return 0;
+	}
+
+	SRC_PUT16(port, sca->dmac[0].cda, 0);
+	inb(port);
+	tmp = SRC_GET16(port, sca->dmac[0].cda);
+	if(tmp != 0) {
+		printf("sr%d: Error reading SCA 0, %x\n", id->id_unit, tmp);
+		return 0;
+	}
+	SRC_PUT16(port, sca->dmac[0].cda, 0x55AA);
+	inb(port);
+	tmp = SRC_GET16(port, sca->dmac[0].cda);
+	if(tmp != 0x55AA) {
+		printf("sr%d: Error reading SCA 0x55AA, %x\n", id->id_unit, tmp);
+		return 0;
+	}
+
+	SRC_SET_OFF(port);
+
+	/*
+	 * We have a card here, fill in what we can.
+	 */
+
+	id->id_msize = SRC_WIN_SIZ;
+
+	hc->iobase = id->id_iobase;
+	hc->mem_start = id->id_maddr;
+	hc->mem_end = id->id_maddr + id->id_msize;
+	hc->cunit = id->id_unit;
+
+	if(id->id_unit == 0)
+		hc->startunit = 0;
+	else
+		hc->startunit = sr_hardc[id->id_unit - 1].startunit +
+				sr_hardc[id->id_unit - 1].numports;
+
+	/*
+	 * Do a little sanity check.
+	 */
+	if(sr_irqtable[ffs(id->id_irq) - 1] == 0)
+		printf("sr%d: Warning illegal interrupt %d\n",
+			id->id_unit, ffs(id->id_irq) - 1);
+	if((hc->numports > NCHAN) || (hc->memsize > (512*1024)))
+		return 0;
+
+	return SRC_IO_SIZ;      /* return the amount of IO addresses used. */
+}
+
+
+/*
+ * Malloc memory for the softc structures.
+ * Reset the card to put it in a known state.
+ * Register the ports on the adapter.
+ * Fill in the info for each port.
+ * Attach each port to sppp and bpf.
+ */
+static int
+srattach(struct isa_device *id)
+{
+	struct sr_hardc *hc = &sr_hardc[id->id_unit];
+	struct sr_softc *sc;
+	struct ifnet *ifp;
+	int unit;
+
+	printf("src%d: %uK RAM, %u ports.\n",
+		id->id_unit,
+		hc->memsize/1024,
+		hc->numports);
+	
+	hc->kdc.kdc_state = DC_BUSY;
+
+	src_init(id);
+
+	sc = hc->sc;
+
+	sr_init_sca(hc);
+
+	/*
+	 * Now configure each port on the card.
+	 */
+	for(unit=0;unit<hc->numports;sc++,unit++) {
+		sc->hc = hc;
+		sc->subunit = unit;
+		sc->unit = hc->startunit + unit;
+		sc->scachan = unit%NCHAN;
+
+		sr_registerdev(id->id_unit, unit);
+
+		sr_init_rx_dmac(sc);
+		sr_init_tx_dmac(sc);
+		sr_init_msci(sc);
+
+		ifp = &sc->ifsppp.pp_if;
+
+		ifp->if_softc = sc;
+		ifp->if_unit = hc->startunit + unit;
+		ifp->if_name = "sr";
+		ifp->if_mtu = PP_MTU;
+		ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
+		ifp->if_ioctl = srioctl;
+		ifp->if_start = srstart;
+		ifp->if_watchdog = srwatchdog;
+
+		sc->ifsppp.pp_flags = PP_KEEPALIVE;
+
+		sc->kdc.kdc_state = DC_IDLE;
+
+		printf("sr%d: Adapter %d, port %d.\n",
+			sc->unit,
+			hc->cunit,
+			sc->subunit);
+
+		sppp_attach((struct ifnet *)&sc->ifsppp);
+		if_attach(ifp);
+
+#if NBPFILTER > 0
+		bpfattach(ifp, DLT_PPP, PPP_HEADER_LEN);
+#endif
+	}
+
+	SRC_SET_OFF(hc->iobase);
+
+	return 1;
+}
+
+/*
+ * First figure out which SCA gave the interrupt.
+ * Process it.
+ * See if there is other interrupts pending.
+ * Repeat until there is no more interrupts.
+ */
+void
+srintr(int unit)
+{
+	struct sr_hardc *hc = &sr_hardc[unit];
+	sca_regs *sca = hc->sca;
+	u_char isr0, isr1, isr2;
+
+	/*
+	 * Loop until no outstanding interrupts.
+	 */
+	isr0 = SRC_GET8(hc->iobase, sca->isr0);
+	isr1 = SRC_GET8(hc->iobase, sca->isr1);
+	isr2 = SRC_GET8(hc->iobase, sca->isr2);
+
+	do {
+		/*
+		 * Acknoledge all the interrupts pending.
+		 *
+		 * XXX Does this really work?
+		 */
+		SRC_PUT8(hc->iobase, sca->isr0, isr0);
+		SRC_PUT8(hc->iobase, sca->isr1, isr1);
+		SRC_PUT8(hc->iobase, sca->isr2, isr2);
+
+		TRC(printf("src%d: SRINTR isr0 %x, isr1 %x, isr2 %x\n",
+			unit,
+			isr0,
+			isr1,
+			isr2));
+
+		if(isr0)
+			sr_msci_intr(hc, isr0);
+
+		if(isr1)
+			sr_dmac_intr(hc, isr1);
+
+		if(isr2)
+			sr_timer_intr(hc, isr2);
+
+		isr0 = SRC_GET8(hc->iobase, sca->isr0);
+		isr1 = SRC_GET8(hc->iobase, sca->isr1);
+		isr2 = SRC_GET8(hc->iobase, sca->isr2);
+	} while (isr0 | isr1 | isr2);
+}
+
+
+/*
+ * This will only start the transmitter. It is assumed that the data
+ * is already there. It is normally called from srstart() or sr_dmac_intr().
+ *
+ */
+static void
+sr_xmit(struct sr_softc *sc)
+{
+	struct ifnet *ifp = &sc->ifsppp.pp_if;
+	dmac_channel *dmac = &sc->hc->sca->dmac[DMAC_TXCH(sc->scachan)];
+
+	SRC_PUT16(sc->hc->iobase, dmac->cda,
+		  (u_short)(sc->block[sc->txb_next_tx].txdesc & 0xffff));
+
+	SRC_PUT16(sc->hc->iobase, dmac->eda,
+		  (u_short)(sc->block[sc->txb_next_tx].txeda & 0xffff));
+	SRC_PUT8(sc->hc->iobase, dmac->dsr, SCA_DSR_DE);
+
+	sc->xmit_busy = 1;
+
+	sc->txb_next_tx++;
+	if(sc->txb_next_tx == SR_TX_BLOCKS)
+		sc->txb_next_tx = 0;
+
+	ifp->if_timer = 2; /* Value in seconds. */
+}
+
+/*
+ * This function will be called from the upper level when a user add a
+ * packet to be send, and from the interrupt handler after a finished
+ * transmit.
+ *
+ * NOTE: it should run at spl_imp().
+ *
+ * This function only place the data in the oncard buffers. It does not
+ * start the transmition. sr_xmit() does that.
+ *
+ * Transmitter idle state is indicated by the IFF_OACTIVE flag. The function
+ * that clears that should ensure that the transmitter and it's DMA is
+ * in a "good" idle state.
+ */
+static void
+srstart(struct ifnet *ifp)
+{
+	struct sr_softc *sc = ifp->if_softc;
+	int i, len, tlen;
+	struct mbuf *mtx;
+	u_char *txdata;
+	sca_descriptor *txdesc;
+	struct buf_block *blkp;
+
+	if(!(ifp->if_flags & IFF_RUNNING))
+		return;
+  
+	/*
+	 * It is OK to set the memory window outside the loop because
+	 * all tx buffers and descriptors are assumed to be in the same
+	 * 16K window.
+	 */
+	SRC_SET_ON(sc->hc->iobase);
+	SRC_SET_MEM(sc->hc->iobase, sc->block[0].txdesc);
+
+top_srstart:
+
+	/*
+	 * See if we have space for more packets.
+	 */
+	if(sc->txb_inuse == SR_TX_BLOCKS) {
+		ifp->if_flags |= IFF_OACTIVE;
+		SRC_SET_OFF(sc->hc->iobase);
+		return;
+	}
+
+	mtx = sppp_dequeue(ifp);
+	if(!mtx) {
+		SRC_SET_OFF(sc->hc->iobase);
+		return;
+	}
+
+	/*
+	 * We stay in this loop until there is nothing in the
+	 * TX queue left or the tx buffers are full.
+	 */
+	i = 0;
+	blkp = &sc->block[sc->txb_new];
+	txdesc = (sca_descriptor *)
+		(sc->hc->mem_start + (blkp->txdesc & SRC_WIN_MSK));
+	txdata = (u_char *)(sc->hc->mem_start + (blkp->txstart & SRC_WIN_MSK));
+	for(;;) {
+		len = mtx->m_pkthdr.len;
+
+		TRC(printf("sr%d: SRstart len %u\n", sc->unit, len));
+
+		/*
+		 * We can do this because the tx buffers don't wrap.
+		 */
+		m_copydata(mtx, 0, len, txdata);
+		tlen = len;
+		while(tlen > SR_BUF_SIZ) {
+			txdesc->stat = 0;
+			txdesc->len = SR_BUF_SIZ;
+			tlen -= SR_BUF_SIZ;
+			txdesc++;
+			txdata += SR_BUF_SIZ;
+			i++;
+		}
+		/* XXX Move into the loop? */
+		txdesc->stat = SCA_DESC_EOM;
+		txdesc->len = tlen;
+		txdesc++;
+		txdata += SR_BUF_SIZ;
+		i++;
+
+#if NBPFILTER > 0
+		if(ifp->if_bpf)
+			bpf_mtap(ifp, mtx);
+#endif
+		m_freem(mtx);
+		++sc->ifsppp.pp_if.if_opackets;
+
+		/*
+		 * Check if we have space for another mbuf.
+		 * XXX This is hardcoded. A packet won't be larger
+		 * than 3 buffers (3 x 512).
+		 */
+		if((i + 3) >= blkp->txmax)
+			break;
+
+		mtx = sppp_dequeue(ifp);
+		if(!mtx)
+			break;
+	}
+
+	blkp->txtail = i;
+
+	/*
+	 * Mark the last descriptor, so that the SCA know where
+	 * to stop.
+	 */
+	txdesc--;
+	txdesc->stat |= SCA_DESC_EOT;
+
+	txdesc = (sca_descriptor *)blkp->txdesc;
+	blkp->txeda = (u_short)((u_int)&txdesc[i]);
+
+	sc->txb_inuse++;
+	sc->txb_new++;
+	if(sc->txb_new == SR_TX_BLOCKS)
+		sc->txb_new = 0;
+
+	if(sc->xmit_busy == 0)
+		sr_xmit(sc);
+
+	goto top_srstart;
+}
+
+static int
+srioctl(struct ifnet *ifp, int cmd, caddr_t data)
+{
+	int s, error;
+	int was_up, should_be_up;
+	struct sppp *sp = (struct sppp *)ifp;
+	struct sr_softc *sc = ifp->if_softc;
+
+	TRC(printf("sr%d: srioctl.\n", ifp->if_unit);)
+
+	if(cmd == SIOCSIFFLAGS) {
+		if(ifp->if_flags & IFF_LINK2)
+			sp->pp_flags |= PP_CISCO;
+		else
+			sp->pp_flags &= ~PP_CISCO;
+	}
+
+	was_up = ifp->if_flags & IFF_RUNNING;
+
+	error = sppp_ioctl(ifp, cmd, data);
+	TRC(printf("sr%d: ioctl: ifsppp.pp_flags = %x, if_flags %x.\n", 
+		ifp->if_unit, ((struct sppp *)ifp)->pp_flags, ifp->if_flags);)
+	if(error)
+		return error;
+
+	if((cmd != SIOCSIFFLAGS) && cmd != (SIOCSIFADDR))
+		return 0;
+
+	TRC(printf("sr%d: srioctl %s.\n", ifp->if_unit, 
+		(cmd == SIOCSIFFLAGS) ? "SIOCSIFFLAGS" : "SIOCSIFADDR");)
+
+	s = splimp();
+	should_be_up = ifp->if_flags & IFF_RUNNING;
+
+	if(!was_up && should_be_up) {
+		/* Interface should be up -- start it. */
+		sr_up(sc);
+		srstart(ifp);
+		/* XXX Clear the IFF_UP flag so that the link
+		 * will only go up after sppp lcp and ipcp negotiation.
+		 */
+		ifp->if_flags &= ~IFF_UP;
+	} else if(was_up && !should_be_up) {
+		/* Interface should be down -- stop it. */
+		sr_down(sc);
+		sppp_flush(ifp);
+	}
+	splx(s);
+	return 0;
+}
+
+/*
+ * This is to catch lost tx interrupts.
+ */
+static void
+srwatchdog(struct ifnet *ifp)
+{
+	struct sr_softc *sc = ifp->if_softc;
+	msci_channel *msci = &sc->hc->sca->msci[sc->scachan];
+
+	if(!(ifp->if_flags & IFF_RUNNING))
+		return;
+
+	/* XXX if(sc->ifsppp.pp_if.if_flags & IFF_DEBUG) */
+		printf("sr%d: transmit failed, "
+			"ST0 %x, ST1 %x, ST3 %x, DSR %x.\n",
+			ifp->if_unit,
+			SRC_GET8(sc->hc->iobase, msci->st0),
+			SRC_GET8(sc->hc->iobase, msci->st1),
+			SRC_GET8(sc->hc->iobase, msci->st3),
+			SRC_GET8(sc->hc->iobase, 
+				sc->hc->sca->dmac[DMAC_TXCH(sc->scachan)].dsr));
+
+	if(SRC_GET8(sc->hc->iobase, msci->st1) & SCA_ST1_UDRN) {
+		SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_TXABORT);
+		SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_TXENABLE);
+		SRC_PUT8(sc->hc->iobase, msci->st1, SCA_ST1_UDRN);
+	}
+
+	sc->xmit_busy = 0;
+	ifp->if_flags &= ~IFF_OACTIVE;
+
+	if(sc->txb_inuse && --sc->txb_inuse)
+		sr_xmit(sc);
+
+	srstart(ifp);
+}
+
+static void
+sr_up(struct sr_softc *sc)
+{
+	sca_regs *sca = sc->hc->sca;
+	msci_channel *msci = &sca->msci[sc->scachan];
+
+	sc->kdc.kdc_state = DC_BUSY;
+
+	/*
+	 * Enable transmitter and receiver.
+	 * Raise DTR and RTS.
+	 * Enable interrupts.
+	 */
+
+	/* XXX
+	 * What about using AUTO mode in msci->md0 ???
+	 */
+	SRC_PUT8(sc->hc->iobase, msci->ctl,
+		SRC_GET8(sc->hc->iobase, msci->ctl) & ~SCA_CTL_RTS);
+
+	if(sc->scachan == 0)
+		outb(sc->hc->iobase + SR_MCR,
+			inb(sc->hc->iobase + SR_MCR) & ~SR_MCR_DTR0);
+	else
+		outb(sc->hc->iobase + SR_MCR,
+			inb(sc->hc->iobase + SR_MCR) & ~SR_MCR_DTR1);
+
+	if(sc->scachan == 0) {
+		SRC_PUT8(sc->hc->iobase, sca->ier0,
+			SRC_GET8(sc->hc->iobase, sca->ier0) | 0x0F);
+		SRC_PUT8(sc->hc->iobase, sca->ier1,
+			SRC_GET8(sc->hc->iobase, sca->ier1) | 0x0F);
+	} else {
+		SRC_PUT8(sc->hc->iobase, sca->ier0,
+			SRC_GET8(sc->hc->iobase, sca->ier0) | 0xF0);
+		SRC_PUT8(sc->hc->iobase, sca->ier1,
+			SRC_GET8(sc->hc->iobase, sca->ier1) | 0xF0);
+	}
+
+	SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_RXENABLE);
+	inb(sc->hc->iobase); /* XXX slow it down a bit. */
+	SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_TXENABLE);
+}
+
+static void
+sr_down(struct sr_softc *sc)
+{
+	sca_regs *sca = sc->hc->sca;
+	msci_channel *msci = &sca->msci[sc->scachan];
+
+	sc->kdc.kdc_state = DC_IDLE;
+
+	/*
+	 * Disable transmitter and receiver.
+	 * Lower DTR and RTS.
+	 * Disable interrupts.
+	 */
+	SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_RXDISABLE);
+	inb(sc->hc->iobase); /* XXX slow it down a bit. */
+	SRC_PUT8(sc->hc->iobase, msci->cmd, SCA_CMD_TXDISABLE);
+
+	SRC_PUT8(sc->hc->iobase, msci->ctl,
+		SRC_GET8(sc->hc->iobase, msci->ctl) | SCA_CTL_RTS);
+
+	if(sc->scachan == 0)
+		outb(sc->hc->iobase + SR_MCR,
+			inb(sc->hc->iobase + SR_MCR) | SR_MCR_DTR0);
+	else
+		outb(sc->hc->iobase + SR_MCR,
+			inb(sc->hc->iobase + SR_MCR) | SR_MCR_DTR1);
+
+	if(sc->scachan == 0) {
+		SRC_PUT8(sc->hc->iobase, sca->ier0,
+			SRC_GET8(sc->hc->iobase, sca->ier0) & ~0x0F);
+		SRC_PUT8(sc->hc->iobase, sca->ier1,
+			SRC_GET8(sc->hc->iobase, sca->ier1) & ~0x0F);
+	} else {
+		SRC_PUT8(sc->hc->iobase, sca->ier0,
+			SRC_GET8(sc->hc->iobase, sca->ier0) & ~0xF0);
+		SRC_PUT8(sc->hc->iobase, sca->ier1,
+			SRC_GET8(sc->hc->iobase, sca->ier1) & ~0xF0);
+	}
+}
+
+/*
+ * Initialize the card, allocate memory for the sr_softc structures
+ * and fill in the pointers.
+ */
+static void
+src_init(struct isa_device *id)
+{
+	struct sr_hardc *hc = &sr_hardc[id->id_unit];
+	struct sr_softc *sc;
+	int x;
+	u_int chanmem;
+	u_int bufmem;
+	u_int next;
+	u_int descneeded;
+	u_char mar;
+
+	sc = hc->sc = malloc(hc->numports * sizeof(struct sr_softc),
+				M_DEVBUF, M_WAITOK);
+	bzero(sc, hc->numports * sizeof(struct sr_softc));
+
+	outb(hc->iobase + SR_PCR, inb(hc->iobase + SR_PCR) | SR_PCR_SCARUN);
+	outb(hc->iobase + SR_PSR, inb(hc->iobase + SR_PSR) | SR_PSR_EN_SCA_DMA);
+	outb(hc->iobase + SR_MCR, SR_MCR_DTR0 |
+				  SR_MCR_DTR1 |
+				  SR_MCR_TE0  |
+				  SR_MCR_TE1);
+	SRC_SET_ON(hc->iobase);
+
+	/*
+	 * Configure the card.
+	 * Mem address, irq, 
+	 */
+	mar = (kvtop(id->id_maddr) >> 16) & SR_PCR_16M_SEL;
+	outb(hc->iobase + SR_PCR,
+		mar | (inb(hc->iobase + SR_PCR) & ~SR_PCR_16M_SEL));
+	mar = kvtop(id->id_maddr) >> 12;
+	outb(hc->iobase + SR_BAR, mar);
+
+	/*
+	 * Get the TX clock direction and configuration.
+	 * The default is a single external clock which is
+	 * used by RX and TX.
+	 */
+	if(id->id_flags & SR_FLAGS_0_CLK_MSK)
+		sc[0].clk_cfg = (id->id_flags & SR_FLAGS_0_CLK_MSK) >>
+				   SR_FLAGS_CLK_SHFT;
+	if((hc->numports == 2) && (id->id_flags & SR_FLAGS_1_CLK_MSK))
+		sc[1].clk_cfg = (id->id_flags & SR_FLAGS_1_CLK_MSK) >>
+				  (SR_FLAGS_CLK_SHFT + SR_FLAGS_CLK_CHAN_SHFT);
+
+	chanmem = hc->memsize / hc->numports;
+	next = 0;
+
+	for(x=0;x<hc->numports;x++, sc++) {
+		int blk;
+
+		for(blk = 0; blk < SR_TX_BLOCKS; blk++) {
+			sc->block[blk].txdesc = next;
+			bufmem = (16 * 1024) / SR_TX_BLOCKS;
+			descneeded = bufmem / SR_BUF_SIZ;
+			sc->block[blk].txstart = sc->block[blk].txdesc +
+				((((descneeded * sizeof(sca_descriptor)) /
+					SR_BUF_SIZ) + 1) * SR_BUF_SIZ);
+			sc->block[blk].txend = next + bufmem;
+			sc->block[blk].txmax =
+				(sc->block[blk].txend - sc->block[blk].txstart)
+				/ SR_BUF_SIZ;
+			next += bufmem;
+
+			TRC(printf("sr%d: blk %d: txdesc %x, txstart %x, "
+				   "txend %x, txmax %d\n",
+				   x,
+				   blk,
+				   sc->block[blk].txdesc,
+				   sc->block[blk].txstart,
+				   sc->block[blk].txend,
+				   sc->block[blk].txmax));
+		}
+
+		sc->rxdesc = next;
+		bufmem = chanmem - (bufmem * SR_TX_BLOCKS);
+		descneeded = bufmem / SR_BUF_SIZ;
+		sc->rxstart = sc->rxdesc +
+				((((descneeded * sizeof(sca_descriptor)) /
+					SR_BUF_SIZ) + 1) * SR_BUF_SIZ);
+		sc->rxend = next + bufmem;
+		sc->rxmax = (sc->rxend - sc->rxstart) / SR_BUF_SIZ;
+		next += bufmem;
+	}
+}
+
+
+/*
+ * The things done here are channel independent.
+ *
+ *   Configure the sca waitstates.
+ *   Configure the global interrupt registers.
+ *   Enable master dma enable.
+ */
+static void
+sr_init_sca(struct sr_hardc *hc)
+{
+	sca_regs *sca = hc->sca;
+
+	/*
+	 * Do the wait registers.
+	 * Set everything to 0 wait states.
+	 */
+	SRC_PUT8(hc->iobase, sca->pabr0, 0);
+	SRC_PUT8(hc->iobase, sca->pabr1, 0);
+	SRC_PUT8(hc->iobase, sca->wcrl, 0);
+	SRC_PUT8(hc->iobase, sca->wcrm, 0);
+	SRC_PUT8(hc->iobase, sca->wcrh, 0);
+
+	/*
+	 * Configure the interrupt registers.
+	 * Most are cleared until the interface is configured.
+	 */
+	SRC_PUT8(hc->iobase, sca->ier0, 0x00); /* MSCI interrupts. */
+	SRC_PUT8(hc->iobase, sca->ier1, 0x00); /* DMAC interrupts */
+	SRC_PUT8(hc->iobase, sca->ier2, 0x00); /* TIMER interrupts. */
+	SRC_PUT8(hc->iobase, sca->itcr, 0x00); /* Use ivr and no intr ack */
+	SRC_PUT8(hc->iobase, sca->ivr, 0x40); /* Interrupt vector. */
+	SRC_PUT8(hc->iobase, sca->imvr, 0x40);
+
+	/*
+	 * Configure the timers.
+	 * XXX Later
+	 */
+
+
+	/*
+	 * Set the DMA channel priority to rotate between
+	 * all four channels.
+	 *
+	 * Enable all dma channels.
+	 */
+	SRC_PUT8(hc->iobase, sca->pcr, SCA_PCR_PR2);
+	SRC_PUT8(hc->iobase, sca->dmer, SCA_DMER_EN);
+}
+
+
+/*
+ * Configure the msci
+ *
+ * NOTE: The serial port configuration is hardcoded at the moment.
+ */
+static void
+sr_init_msci(struct sr_softc *sc)
+{
+	msci_channel *msci = &sc->hc->sca->msci[sc->scachan];
+	u_short iobase = sc->hc->iobase;
+
+	SRC_PUT8(iobase, msci->cmd, SCA_CMD_RESET);
+
+	SRC_PUT8(iobase, msci->md0, SCA_MD0_CRC_1 |
+				    SCA_MD0_CRC_CCITT |
+				    SCA_MD0_CRC_ENABLE |
+				    SCA_MD0_MODE_HDLC);
+	SRC_PUT8(iobase, msci->md1, SCA_MD1_NOADDRCHK);
+	SRC_PUT8(iobase, msci->md2, SCA_MD2_DUPLEX | SCA_MD2_NRZ);
+
+	/*
+	 * According to the manual I should give a reset after changing the
+	 * mode registers.
+	 */
+	SRC_PUT8(iobase, msci->cmd, SCA_CMD_RXRESET);
+	SRC_PUT8(iobase, msci->ctl, SCA_CTL_IDLPAT |
+				    SCA_CTL_UDRNC |
+				    SCA_CTL_RTS);
+
+	/*
+	 * XXX Later we will have to support different clock settings.
+	 */
+	switch(sc->clk_cfg) {
+	default:
+	case SR_FLAGS_EXT_CLK:
+		/*
+		 * For now all interfaces are programmed to use the
+		 * RX clock for the TX clock.
+		 */
+		SRC_PUT8(iobase, msci->rxs, SCA_RXS_CLK_RXC0 | SCA_RXS_DIV1);
+		SRC_PUT8(iobase, msci->txs, SCA_TXS_CLK_RX | SCA_TXS_DIV1);
+		break;
+	case SR_FLAGS_EXT_SEP_CLK:
+		SRC_PUT8(iobase, msci->rxs, SCA_RXS_CLK_RXC0 | SCA_RXS_DIV1);
+		SRC_PUT8(iobase, msci->txs, SCA_TXS_CLK_TXC | SCA_TXS_DIV1);
+		break;
+	case SR_FLAGS_INT_CLK:
+		/*
+		 * XXX I do need some code to set the baud rate here!
+		 */
+		SRC_PUT8(iobase, msci->rxs, SCA_RXS_CLK_INT | SCA_RXS_DIV1);
+		SRC_PUT8(iobase, msci->txs, SCA_TXS_CLK_INT | SCA_TXS_DIV1);
+
+		SRC_PUT8(iobase, msci->tmc, 153);
+
+		if(sc->scachan == 0)
+			outb(iobase + SR_MCR, inb(iobase + SR_MCR) |
+						  SR_MCR_ETC0);
+		else
+			outb(iobase + SR_MCR, inb(iobase + SR_MCR) |
+						  SR_MCR_ETC1);
+	}
+
+	/* XXX
+	 * Disable all interrupts for now. I think if you are using
+	 * the dmac you don't use these interrupts.
+	 */
+	SRC_PUT8(iobase, msci->ie0, 0);
+	SRC_PUT8(iobase, msci->ie1, 0x0C); /* XXX CTS and DCD level change. */
+	SRC_PUT8(iobase, msci->ie2, 0);
+	SRC_PUT8(iobase, msci->fie, 0);
+
+	SRC_PUT8(iobase, msci->sa0, 0);
+	SRC_PUT8(iobase, msci->sa1, 0);
+
+	SRC_PUT8(iobase, msci->idl, 0x7E); /* XXX This is what cisco does. */
+
+	SRC_PUT8(iobase, msci->rrc, 0x0E);
+	SRC_PUT8(iobase, msci->trc0, 0x10);
+	SRC_PUT8(iobase, msci->trc1, 0x1F);
+}
+
+/*
+ * Configure the rx dma controller.
+ */
+static void
+sr_init_rx_dmac(struct sr_softc *sc)
+{
+	dmac_channel *dmac = &sc->hc->sca->dmac[DMAC_RXCH(sc->scachan)];
+	sca_descriptor *rxd;
+	u_int rxbuf;
+	u_int rxda;
+	u_int rxda_d;
+	u_short iobase = sc->hc->iobase;
+
+	SRC_SET_MEM(iobase, sc->rxdesc);
+
+	rxd = (sca_descriptor *)(sc->hc->mem_start + (sc->rxdesc&SRC_WIN_MSK));
+	rxda_d = (u_int)sc->hc->mem_start - (sc->rxdesc & ~SRC_WIN_MSK);
+
+	for(rxbuf=sc->rxstart;rxbuf<sc->rxend;rxbuf += SR_BUF_SIZ, rxd++) {
+		rxda = (u_int)&rxd[1] - rxda_d;
+		rxd->cp = (u_short)(rxda & 0xfffful);
+
+		TRC(printf("Descrp %p, data pt %p, data long %lx, ",
+			&sc->rxdesc[x], rxinuse->buf, rxbuf));
+
+		rxd->bp = (u_short)(rxbuf & 0xfffful);
+		rxd->bpb = (u_char)((rxbuf >> 16) & 0xff);
+		rxd->len = 0;
+		rxd->stat = 0xff; /* The sca write here when it is finished. */
+
+		TRC(printf("bpb %x, bp %x.\n", rxd->bpb, rxd->bp));
+	}
+	rxd--;
+	rxd->cp = (u_short)(sc->rxdesc & 0xfffful);
+
+	sc->rxhind = 0;
+
+	SRC_PUT8(iobase, dmac->dsr, 0);    /* Disable DMA transfer */
+	SRC_PUT8(iobase, dmac->dcr, SCA_DCR_ABRT);
+
+	/* XXX maybe also SCA_DMR_CNTE */
+	SRC_PUT8(iobase, dmac->dmr, SCA_DMR_TMOD | SCA_DMR_NF);
+	SRC_PUT16(iobase, dmac->bfl, SR_BUF_SIZ);
+
+	SRC_PUT16(iobase, dmac->cda, (u_short)(sc->rxdesc & 0xffff));
+	SRC_PUT8(iobase, dmac->sarb, (u_char)((sc->rxdesc >> 16) & 0xff));
+
+	rxd = (sca_descriptor *)sc->rxstart;
+	SRC_PUT16(iobase, dmac->eda,
+			(u_short)((u_int)&rxd[sc->rxmax - 1] & 0xffff));
+
+	SRC_PUT8(iobase, dmac->dir, 0xF0);
+
+	SRC_PUT8(iobase, dmac->dsr, SCA_DSR_DE);
+}
+
+/*
+ * Configure the TX DMA descriptors.
+ * Initialize the needed values and chain the descriptors.
+ */
+static void
+sr_init_tx_dmac(struct sr_softc *sc)
+{
+	dmac_channel *dmac = &sc->hc->sca->dmac[DMAC_TXCH(sc->scachan)];
+	struct buf_block *blkp;
+	int blk;
+	sca_descriptor *txd;
+	u_int txbuf;
+	u_int txda;
+	u_int txda_d;
+	u_short iobase = sc->hc->iobase;
+
+	SRC_SET_MEM(iobase, sc->block[0].txdesc);
+
+	for(blk = 0; blk < SR_TX_BLOCKS; blk++) {
+		blkp = &sc->block[blk];
+		txd = (sca_descriptor *)(sc->hc->mem_start +
+					(blkp->txdesc & SRC_WIN_MSK));
+		txda_d = (u_int)sc->hc->mem_start -
+				(blkp->txdesc & ~SRC_WIN_MSK);
+
+		txbuf=blkp->txstart;
+		for(;txbuf<blkp->txend;txbuf += SR_BUF_SIZ, txd++) {
+			txda = (u_int)&txd[1] - txda_d;
+			txd->cp = (u_short)(txda & 0xfffful);
+
+			txd->bp = (u_short)(txbuf & 0xfffful);
+			txd->bpb = (u_char)((txbuf >> 16) & 0xff);
+			TRC(printf("sr%d: txbuf %x, bpb %x, bp %x\n",
+				sc->unit, txbuf, txd->bpb, txd->bp));
+			txd->len = 0;
+			txd->stat = 0;
+		}
+		txd--;
+		txd->cp = (u_short)(blkp->txdesc & 0xfffful);
+
+		blkp->txtail = (u_int)txd - (u_int)sc->hc->mem_start;
+		TRC(printf("TX Descriptors start %x, end %x.\n",
+			blkp->txhead,
+			blkp->txtail));
+	}
+
+	SRC_PUT8(iobase, dmac->dsr, 0); /* Disable DMA */
+	SRC_PUT8(iobase, dmac->dcr, SCA_DCR_ABRT);
+	SRC_PUT8(iobase, dmac->dmr, SCA_DMR_TMOD | SCA_DMR_NF);
+	SRC_PUT8(iobase, dmac->dir, SCA_DIR_EOT | SCA_DIR_BOF | SCA_DIR_COF);
+
+	SRC_PUT8(iobase, dmac->sarb,
+			(u_char)((sc->block[0].txdesc >> 16) & 0xff));
+}
+
+
+/*
+ * Look through the descriptors to see if there is a complete packet
+ * available. Stop if we get to where the sca is busy.
+ *
+ * Return the length and status of the packet.
+ * Return nonzero if there is a packet available.
+ *
+ * NOTE:
+ * It seems that we get the interrupt a bit early. The updateing of
+ * descriptor values is not always completed when this is called.
+ */
+static int
+sr_packet_avail(struct sr_softc *sc,
+		    int *len,
+		    u_char *rxstat)
+{
+	sca_descriptor *rxdesc;
+	sca_descriptor *endp;
+	sca_descriptor *cda;
+
+	cda = (sca_descriptor *)(sc->hc->mem_start +
+	      (SRC_GET16(sc->hc->iobase, 
+			sc->hc->sca->dmac[DMAC_RXCH(sc->scachan)].cda) &
+				SRC_WIN_MSK));
+
+	SRC_SET_MEM(sc->hc->iobase, sc->rxdesc);
+	rxdesc = (sca_descriptor *)
+			(sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+	endp = rxdesc;
+	rxdesc = &rxdesc[sc->rxhind];
+	endp = &endp[sc->rxmax];
+
+	*len = 0;
+
+	while(rxdesc != cda) {
+		*len += rxdesc->len;
+
+		if(rxdesc->stat & SCA_DESC_EOM) {
+			*rxstat = rxdesc->stat;
+			TRC(printf("sr%d: PKT AVAIL len %d, %x, bufs %u.\n",
+				sc->unit, *len, *rxstat, x));
+			return 1;
+		}
+
+		rxdesc++;
+		if(rxdesc == endp)
+			rxdesc = (sca_descriptor *)
+			       (sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+	}
+
+	*len = 0;
+	*rxstat = 0;
+	return 0;
+}
+
+
+/*
+ * Copy a packet from the on card memory into a provided mbuf.
+ * Take into account that buffers wrap and that a packet may
+ * be larger than a buffer.
+ */
+static void 
+sr_copy_rxbuf(struct mbuf *m,
+		   struct sr_softc *sc,
+		   int len)
+{
+	sca_descriptor *rxdesc;
+	u_int rxdata;
+	u_int rxmax;
+	u_int off = 0;
+	u_int tlen;
+
+	rxdata = sc->rxstart + (sc->rxhind * SR_BUF_SIZ);
+	rxmax = sc->rxstart + (sc->rxmax * SR_BUF_SIZ);
+
+	rxdesc = (sca_descriptor *)
+			(sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+	rxdesc = &rxdesc[sc->rxhind];
+
+	while(len) {
+		tlen = (len < SR_BUF_SIZ) ? len : SR_BUF_SIZ;
+		SRC_SET_MEM(sc->hc->iobase, rxdata);
+		bcopy(sc->hc->mem_start + (rxdata & SRC_WIN_MSK), 
+			mtod(m, caddr_t) + off,
+			tlen);
+
+		off += tlen;
+		len -= tlen;
+
+		SRC_SET_MEM(sc->hc->iobase, sc->rxdesc);
+		rxdesc->len = 0;
+		rxdesc->stat = 0xff;
+
+		rxdata += SR_BUF_SIZ;
+		rxdesc++;
+		if(rxdata == rxmax) {
+			rxdata = sc->rxstart;
+			rxdesc = (sca_descriptor *)
+				(sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+		}
+	}
+}
+
+/*
+ * If single is set, just eat a packet. Otherwise eat everything up to
+ * where cda points. Update pointers to point to the next packet.
+ */
+static void
+sr_eat_packet(struct sr_softc *sc, int single)
+{
+	sca_descriptor *rxdesc;
+	sca_descriptor *endp;
+	sca_descriptor *cda;
+	int loopcnt = 0;
+	u_char stat;
+
+	cda = (sca_descriptor *)(sc->hc->mem_start +
+	      (SRC_GET16(sc->hc->iobase,
+			sc->hc->sca->dmac[DMAC_RXCH(sc->scachan)].cda) &
+				SRC_WIN_MSK));
+
+	/*
+	 * Loop until desc->stat == (0xff || EOM)
+	 * Clear the status and length in the descriptor.
+	 * Increment the descriptor.
+	 */
+	SRC_SET_MEM(sc->hc->iobase, sc->rxdesc);
+	rxdesc = (sca_descriptor *)
+		(sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+	endp = rxdesc;
+	rxdesc = &rxdesc[sc->rxhind];
+	endp = &endp[sc->rxmax];
+
+	while(rxdesc != cda) {
+		loopcnt++;
+		if(loopcnt > sc->rxmax) {
+			printf("sr%d: eat pkt %d loop, cda %x, "
+			       "rxdesc %x, stat %x.\n",
+			       sc->unit,
+			       loopcnt,
+			       cda,
+			       rxdesc,
+			       rxdesc->stat);
+			break;
+		}
+
+		stat = rxdesc->stat;
+
+		rxdesc->len = 0;
+		rxdesc->stat = 0xff;
+
+		rxdesc++;
+		sc->rxhind++;
+		if(rxdesc == endp) {
+			rxdesc = (sca_descriptor *)
+			       (sc->hc->mem_start + (sc->rxdesc & SRC_WIN_MSK));
+			sc->rxhind = 0;
+		}
+
+		if(single && (stat == SCA_DESC_EOM))
+			break;
+	}
+
+	/*
+	 * Update the eda to the previous descriptor.
+	 */
+	rxdesc = (sca_descriptor *)sc->rxdesc;
+	rxdesc = &rxdesc[(sc->rxhind + sc->rxmax - 2 ) % sc->rxmax];
+
+	SRC_PUT16(sc->hc->iobase,
+		  sc->hc->sca->dmac[DMAC_RXCH(sc->scachan)].eda,
+		  (u_short)((u_int)rxdesc & 0xffff));
+}
+
+
+/*
+ * While there is packets available in the rx buffer, read them out
+ * into mbufs and ship them off.
+ */
+static void
+sr_get_packets(struct sr_softc *sc)
+{
+	sca_descriptor *rxdesc;
+	struct mbuf *m = NULL;
+	int i;
+	int len;
+	u_char rxstat;
+
+	SRC_SET_ON(sc->hc->iobase);
+
+	while(sr_packet_avail(sc, &len, &rxstat)) {
+		if((rxstat & SCA_DESC_ERRORS) == 0) {
+			MGETHDR(m, M_DONTWAIT, MT_DATA);
+			if(m == NULL) {
+				/* eat packet if get mbuf fail!! */
+				sr_eat_packet(sc, 1);
+				continue;
+			}
+			m->m_pkthdr.rcvif = &sc->ifsppp.pp_if;
+			m->m_pkthdr.len = m->m_len = len;
+			if(len > MHLEN) {
+				MCLGET(m, M_DONTWAIT);
+				if((m->m_flags & M_EXT) == 0) {
+					m_freem(m);
+					sr_eat_packet(sc, 1);
+					continue;
+				}
+			}
+			sr_copy_rxbuf(m, sc, len);
+#if NBPFILTER > 0
+			if(sc->ifsppp.pp_if.if_bpf)
+				bpf_mtap(&sc->ifsppp.pp_if, m);
+#endif
+			sppp_input(&sc->ifsppp.pp_if, m);
+			sc->ifsppp.pp_if.if_ipackets++;
+
+			/*
+			 * Update the eda to the previous descriptor.
+			 */
+			i = (len + SR_BUF_SIZ - 1) / SR_BUF_SIZ;
+			sc->rxhind = (sc->rxhind + i) % sc->rxmax;
+
+			rxdesc = (sca_descriptor *)sc->rxdesc;
+			rxdesc =
+			     &rxdesc[(sc->rxhind + sc->rxmax - 2 ) % sc->rxmax];
+
+			SRC_PUT16(sc->hc->iobase,
+				  sc->hc->sca->dmac[DMAC_RXCH(sc->scachan)].eda,
+				  (u_short)((u_int)rxdesc & 0xffff));
+		} else {
+			msci_channel *msci = &sc->hc->sca->msci[sc->scachan];
+
+			sr_eat_packet(sc, 1);
+
+			sc->ifsppp.pp_if.if_ierrors++;
+
+			TRCL(printf("sr%d: Receive error chan %d, "
+				    "stat %x, msci st3 %x,"
+				    "rxhind %d, cda %x, eda %x.\n",
+				    sc->unit,
+				    sc->scachan, 
+				    rxstat,
+				    SRC_GET8(sc->hc->iobase, msci->st3),
+					     sc->rxhind,
+				    SRC_GET16(sc->hc->iobase,
+					      sc->hc->sca->dmac[
+					      DMAC_RXCH(sc->scachan)].cda),
+				    SRC_GET16(sc->hc->iobase,
+					      sc->hc->sca->dmac[
+					      DMAC_RXCH(sc->scachan)].eda)));
+		}
+	}
+
+	SRC_SET_OFF(sc->hc->iobase);
+}
+
+
+/*
+ * All DMA interrupts come here.
+ *
+ * Each channel has two interrupts.
+ * Interrupt A for errors and Interrupt B for normal stuff like end
+ * of transmit or receive dmas.
+ */
+static void
+sr_dmac_intr(struct sr_hardc *hc, u_char isr1)
+{
+	u_char dsr;
+	u_char dotxstart = isr1;
+	int mch;
+	struct sr_softc *sc;
+	sca_regs *sca = hc->sca;
+	dmac_channel *dmac;
+
+	mch = 0;
+	/*
+	 * Shortcut if there is no interrupts for dma channel 0 or 1
+	 */
+	if((isr1 & 0x0F) == 0) {
+		mch = 1;
+		isr1 >>= 4;
+	}
+
+	do {
+		sc = &hc->sc[mch];
+
+		/*
+		 * Transmit channel
+		 */
+		if(isr1 & 0x0C) {
+			dmac = &sca->dmac[DMAC_TXCH(mch)];
+
+			dsr = SRC_GET8(hc->iobase, dmac->dsr);
+			SRC_PUT8(hc->iobase, dmac->dsr, dsr);
+
+			/* Counter overflow */
+			if(dsr & SCA_DSR_COF) {
+				printf("sr%d: TX DMA Counter overflow, "
+					"txpacket no %lu.\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_opackets);
+				sc->ifsppp.pp_if.if_oerrors++;
+			}
+
+			/* Buffer overflow */
+			if(dsr & SCA_DSR_BOF) {
+				printf("sr%d: TX DMA Buffer overflow, "
+					"txpacket no %lu, dsr %02x, "
+					"cda %04x, eda %04x.\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_opackets,
+					dsr,
+					SRC_GET16(hc->iobase, dmac->cda),
+					SRC_GET16(hc->iobase, dmac->eda));
+				sc->ifsppp.pp_if.if_oerrors++;
+			}
+
+			/* End of Transfer */
+			if(dsr & SCA_DSR_EOT) {
+				/*
+				 * This should be the most common case.
+				 *
+				 * Clear the IFF_OACTIVE flag.
+				 *
+				 * Call srstart to start a new transmit if
+				 * there is data to transmit.
+				 */
+				sc->xmit_busy = 0;
+				sc->ifsppp.pp_if.if_flags &= ~IFF_OACTIVE;
+				sc->ifsppp.pp_if.if_timer = 0;
+
+				if(sc->txb_inuse && --sc->txb_inuse)
+					sr_xmit(sc);
+			}
+		}
+
+		/*
+		 * Receive channel
+		 */
+		if(isr1 & 0x03) {
+			dmac = &sca->dmac[DMAC_RXCH(mch)];
+
+			dsr = SRC_GET8(hc->iobase, dmac->dsr);
+			SRC_PUT8(hc->iobase, dmac->dsr, dsr);
+
+			TRC(printf("SR: RX DSR %x\n", dsr));
+
+			/* End of frame */
+			if(dsr & SCA_DSR_EOM) {
+				TRC(int tt = sc->ifsppp.pp_if.if_ipackets;)
+				TRC(int ind = sc->rxhind;)
+
+				sr_get_packets(sc);
+				TRC(
+				if(tt == sc->ifsppp.pp_if.if_ipackets) {
+					sca_descriptor *rxdesc;
+					int i;
+
+					printf("SR: RXINTR isr1 %x, dsr %x, "
+					       "no data %d pkts, orxhind %d.\n",
+					       dotxstart,
+					       dsr,
+					       tt,
+					       ind);
+					printf("SR: rxdesc %x, rxstart %x, "
+					       "rxend %x, rxhind %d, "
+					       "rxmax %d.\n",
+					       sc->rxdesc,
+					       sc->rxstart,
+					       sc->rxend,
+					       sc->rxhind,
+					       sc->rxmax);
+					printf("SR: cda %x, eda %x.\n",
+					       SRC_GET16(hc->iobase, dmac->cda),
+					       SRC_GET16(hc->iobase, dmac->eda));
+
+					SRC_SET_ON(hc->iobase);
+					SRC_SET_MEM(hc->iobase, sc->rxdesc);
+					rxdesc = (sca_descriptor *)
+						 (hc->mem_start +
+						  (sc->rxdesc & SRC_WIN_MSK));
+					rxdesc = &rxdesc[sc->rxhind];
+					for(i=0;i<3;i++,rxdesc++)
+						printf("SR: rxdesc->stat %x, "
+							"len %d.\n",
+							rxdesc->stat,
+							rxdesc->len);
+					SRC_SET_OFF(hc->iobase);
+				})
+			}
+
+			/* Counter overflow */
+			if(dsr & SCA_DSR_COF) {
+				printf("sr%d: RX DMA Counter overflow, "
+					"rxpkts %lu.\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_ipackets);
+				sc->ifsppp.pp_if.if_ierrors++;
+			}
+
+			/* Buffer overflow */
+			if(dsr & SCA_DSR_BOF) {
+				printf("sr%d: RX DMA Buffer overflow, "
+					"rxpkts %lu, rxind %d, "
+					"cda %x, eda %x, dsr %x.\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_ipackets,
+					sc->rxhind,
+					SRC_GET16(hc->iobase, dmac->cda),
+					SRC_GET16(hc->iobase, dmac->eda),
+					dsr);
+				/*
+				 * Make sure we eat as many as possible.
+				 * Then get the system running again.
+				 */
+				SRC_SET_ON(sc->hc->iobase);
+				sr_eat_packet(sc, 0);
+				sc->ifsppp.pp_if.if_ierrors++;
+				SRC_PUT8(hc->iobase,
+					 sca->msci[mch].cmd,
+					 SCA_CMD_RXMSGREJ);
+				SRC_PUT8(hc->iobase, dmac->dsr, SCA_DSR_DE);
+
+				TRC(printf("sr%d: RX DMA Buffer overflow, "
+					"rxpkts %lu, rxind %d, "
+					"cda %x, eda %x, dsr %x. After\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_ipackets,
+					sc->rxhind,
+					SRC_GET16(hc->iobase, dmac->cda),
+					SRC_GET16(hc->iobase, dmac->eda),
+					SRC_GET8(hc->iobase, dmac->dsr));)
+				SRC_SET_OFF(sc->hc->iobase);
+			}
+
+			/* End of Transfer */
+			if(dsr & SCA_DSR_EOT) {
+				/*
+				 * If this happen, it means that we are
+				 * receiving faster than what the processor
+				 * can handle.
+				 *
+				 * XXX We should enable the dma again.
+				 */
+				printf("sr%d: RX End of transfer, rxpkts %lu.\n",
+					sc->unit,
+					sc->ifsppp.pp_if.if_ipackets);
+				sc->ifsppp.pp_if.if_ierrors++;
+			}
+		}
+
+		isr1 >>= 4;
+
+		mch++;
+	}while((mch<NCHAN) && isr1);
+
+	/*
+	 * Now that we have done all the urgent things, see if we
+	 * can fill the transmit buffers.
+	 */
+	for(mch = 0; mch < NCHAN; mch++) {
+		if(dotxstart & 0x0C) {
+			sc = &hc->sc[mch];
+			srstart(&sc->ifsppp.pp_if);
+		}
+		dotxstart >>= 4;
+	}
+}
+
+static void
+sr_msci_intr(struct sr_hardc *hc, u_char isr0)
+{
+	printf("src%d: SRINTR: MSCI\n", hc->cunit);
+}
+
+static void
+sr_timer_intr(struct sr_hardc *hc, u_char isr2)
+{
+	printf("src%d: SRINTR: TIMER\n", hc->cunit);
+}
+
+/*
+ ********************************* END ************************************
+ */
+