sched: make early bootup sched_clock() use safer

[wrt350n-kernel.git] / drivers / net / appletalk / ltpc.c

/***    ltpc.c -- a driver for the LocalTalk PC card.
 *
 *      Copyright (c) 1995,1996 Bradford W. Johnson <johns393@maroon.tc.umn.edu>
 *
 *      This software may be used and distributed according to the terms
 *      of the GNU General Public License, incorporated herein by reference.
 *
 *      This is ALPHA code at best.  It may not work for you.  It may
 *      damage your equipment.  It may damage your relations with other
 *      users of your network.  Use it at your own risk!
 *
 *      Based in part on:
 *      skeleton.c      by Donald Becker
 *      dummy.c         by Nick Holloway and Alan Cox
 *      loopback.c      by Ross Biro, Fred van Kampen, Donald Becker
 *      the netatalk source code (UMICH)
 *      lots of work on the card...
 *
 *      I do not have access to the (proprietary) SDK that goes with the card.
 *      If you do, I don't want to know about it, and you can probably write
 *      a better driver yourself anyway.  This does mean that the pieces that
 *      talk to the card are guesswork on my part, so use at your own risk!
 *
 *      This is my first try at writing Linux networking code, and is also
 *      guesswork.  Again, use at your own risk!  (Although on this part, I'd
 *      welcome suggestions)
 *
 *      This is a loadable kernel module which seems to work at my site
 *      consisting of a 1.2.13 linux box running netatalk 1.3.3, and with
 *      the kernel support from 1.3.3b2 including patches routing.patch
 *      and ddp.disappears.from.chooser.  In order to run it, you will need
 *      to patch ddp.c and aarp.c in the kernel, but only a little...
 *
 *      I'm fairly confident that while this is arguably badly written, the
 *      problems that people experience will be "higher level", that is, with
 *      complications in the netatalk code.  The driver itself doesn't do
 *      anything terribly complicated -- it pretends to be an ether device
 *      as far as netatalk is concerned, strips the DDP data out of the ether
 *      frame and builds a LLAP packet to send out the card.  In the other
 *      direction, it receives LLAP frames from the card and builds a fake
 *      ether packet that it then tosses up to the networking code.  You can
 *      argue (correctly) that this is an ugly way to do things, but it
 *      requires a minimal amount of fooling with the code in ddp.c and aarp.c.
 *
 *      The card will do a lot more than is used here -- I *think* it has the
 *      layers up through ATP.  Even if you knew how that part works (which I
 *      don't) it would be a big job to carve up the kernel ddp code to insert
 *      things at a higher level, and probably a bad idea...
 *
 *      There are a number of other cards that do LocalTalk on the PC.  If
 *      nobody finds any insurmountable (at the netatalk level) problems
 *      here, this driver should encourage people to put some work into the
 *      other cards (some of which I gather are still commercially available)
 *      and also to put hooks for LocalTalk into the official ddp code.
 *
 *      I welcome comments and suggestions.  This is my first try at Linux
 *      networking stuff, and there are probably lots of things that I did
 *      suboptimally.  
 *
 ***/

/***
 *
 * $Log: ltpc.c,v $
 * Revision 1.1.2.1  2000/03/01 05:35:07  jgarzik
 * at and tr cleanup
 *
 * Revision 1.8  1997/01/28 05:44:54  bradford
 * Clean up for non-module a little.
 * Hacked about a bit to clean things up - Alan Cox 
 * Probably broken it from the origina 1.8
 *

 * 1998/11/09: David Huggins-Daines <dhd@debian.org>
 * Cleaned up the initialization code to use the standard autoirq methods,
   and to probe for things in the standard order of i/o, irq, dma.  This
   removes the "reset the reset" hack, because I couldn't figure out an
   easy way to get the card to trigger an interrupt after it.
 * Added support for passing configuration parameters on the kernel command
   line and through insmod
 * Changed the device name from "ltalk0" to "lt0", both to conform with the
   other localtalk driver, and to clear up the inconsistency between the
   module and the non-module versions of the driver :-)
 * Added a bunch of comments (I was going to make some enums for the state
   codes and the register offsets, but I'm still not sure exactly what their
   semantics are)
 * Don't poll anymore in interrupt-driven mode
 * It seems to work as a module now (as of 2.1.127), but I don't think
   I'm responsible for that...

 *
 * Revision 1.7  1996/12/12 03:42:33  bradford
 * DMA alloc cribbed from 3c505.c.
 *
 * Revision 1.6  1996/12/12 03:18:58  bradford
 * Added virt_to_bus; works in 2.1.13.
 *
 * Revision 1.5  1996/12/12 03:13:22  root
 * xmitQel initialization -- think through better though.
 *
 * Revision 1.4  1996/06/18 14:55:55  root
 * Change names to ltpc. Tabs. Took a shot at dma alloc,
 * although more needs to be done eventually.
 *
 * Revision 1.3  1996/05/22 14:59:39  root
 * Change dev->open, dev->close to track dummy.c in 1.99.(around 7)
 *
 * Revision 1.2  1996/05/22 14:58:24  root
 * Change tabs mostly.
 *
 * Revision 1.1  1996/04/23 04:45:09  root
 * Initial revision
 *
 * Revision 0.16  1996/03/05 15:59:56  root
 * Change ARPHRD_LOCALTLK definition to the "real" one.
 *
 * Revision 0.15  1996/03/05 06:28:30  root
 * Changes for kernel 1.3.70.  Still need a few patches to kernel, but
 * it's getting closer.
 *
 * Revision 0.14  1996/02/25 17:38:32  root
 * More cleanups.  Removed query to card on get_stats.
 *
 * Revision 0.13  1996/02/21  16:27:40  root
 * Refix debug_print_skb.  Fix mac.raw gotcha that appeared in 1.3.65.
 * Clean up receive code a little.
 *
 * Revision 0.12  1996/02/19  16:34:53  root
 * Fix debug_print_skb.  Kludge outgoing snet to 0 when using startup
 * range.  Change debug to mask: 1 for verbose, 2 for higher level stuff
 * including packet printing, 4 for lower level (card i/o) stuff.
 *
 * Revision 0.11  1996/02/12  15:53:38  root
 * Added router sends (requires new aarp.c patch)
 *
 * Revision 0.10  1996/02/11  00:19:35  root
 * Change source LTALK_LOGGING debug switch to insmod ... debug=2.
 *
 * Revision 0.9  1996/02/10  23:59:35  root
 * Fixed those fixes for 1.2 -- DANGER!  The at.h that comes with netatalk
 * has a *different* definition of struct sockaddr_at than the Linux kernel
 * does.  This is an "insidious and invidious" bug...
 * (Actually the preceding comment is false -- it's the atalk.h in the
 * ancient atalk-0.06 that's the problem)
 *
 * Revision 0.8  1996/02/10 19:09:00  root
 * Merge 1.3 changes.  Tested OK under 1.3.60.
 *
 * Revision 0.7  1996/02/10 17:56:56  root
 * Added debug=1 parameter on insmod for debugging prints.  Tried
 * to fix timer unload on rmmod, but I don't think that's the problem.
 *
 * Revision 0.6  1995/12/31  19:01:09  root
 * Clean up rmmod, irq comments per feedback from Corin Anderson (Thanks Corey!)
 * Clean up initial probing -- sometimes the card wakes up latched in reset.
 *
 * Revision 0.5  1995/12/22  06:03:44  root
 * Added comments in front and cleaned up a bit.
 * This version sent out to people.
 *
 * Revision 0.4  1995/12/18  03:46:44  root
 * Return shortDDP to longDDP fake to 0/0.  Added command structs.
 *
 ***/

/* ltpc jumpers are:
*
*       Interrupts -- set at most one.  If none are set, the driver uses
*       polled mode.  Because the card was developed in the XT era, the
*       original documentation refers to IRQ2.  Since you'll be running
*       this on an AT (or later) class machine, that really means IRQ9.
*
*       SW1     IRQ 4
*       SW2     IRQ 3
*       SW3     IRQ 9 (2 in original card documentation only applies to XT)
*
*
*       DMA -- choose DMA 1 or 3, and set both corresponding switches.
*
*       SW4     DMA 3
*       SW5     DMA 1
*       SW6     DMA 3
*       SW7     DMA 1
*
*
*       I/O address -- choose one.  
*
*       SW8     220 / 240
*/

/*      To have some stuff logged, do 
*       insmod ltpc.o debug=1
*
*       For a whole bunch of stuff, use higher numbers.
*
*       The default is 0, i.e. no messages except for the probe results.
*/

/* insmod-tweakable variables */
static int debug;
#define DEBUG_VERBOSE 1
#define DEBUG_UPPER 2
#define DEBUG_LOWER 4

static int io;
static int irq;
static int dma;

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/spinlock.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_ltalk.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/atalk.h>
#include <linux/bitops.h>

#include <asm/system.h>
#include <asm/dma.h>
#include <asm/io.h>

/* our stuff */
#include "ltpc.h"

static DEFINE_SPINLOCK(txqueue_lock);
static DEFINE_SPINLOCK(mbox_lock);

/* function prototypes */
static int do_read(struct net_device *dev, void *cbuf, int cbuflen,
        void *dbuf, int dbuflen);
static int sendup_buffer (struct net_device *dev);

/* Dma Memory related stuff, cribbed directly from 3c505.c */

static unsigned long dma_mem_alloc(int size)
{
        int order = get_order(size);

        return __get_dma_pages(GFP_KERNEL, order);
}

/* DMA data buffer, DMA command buffer */
static unsigned char *ltdmabuf;
static unsigned char *ltdmacbuf;

/* private struct, holds our appletalk address */

struct ltpc_private
{
        struct net_device_stats stats;
        struct atalk_addr my_addr;
};

/* transmit queue element struct */

struct xmitQel {
        struct xmitQel *next;
        /* command buffer */
        unsigned char *cbuf;
        short cbuflen;
        /* data buffer */
        unsigned char *dbuf;
        short dbuflen;
        unsigned char QWrite;   /* read or write data */
        unsigned char mailbox;
};

/* the transmit queue itself */

static struct xmitQel *xmQhd, *xmQtl;

static void enQ(struct xmitQel *qel)
{
        unsigned long flags;
        qel->next = NULL;
        
        spin_lock_irqsave(&txqueue_lock, flags);
        if (xmQtl) {
                xmQtl->next = qel;
        } else {
                xmQhd = qel;
        }
        xmQtl = qel;
        spin_unlock_irqrestore(&txqueue_lock, flags);

        if (debug & DEBUG_LOWER)
                printk("enqueued a 0x%02x command\n",qel->cbuf[0]);
}

static struct xmitQel *deQ(void)
{
        unsigned long flags;
        int i;
        struct xmitQel *qel=NULL;
        
        spin_lock_irqsave(&txqueue_lock, flags);
        if (xmQhd) {
                qel = xmQhd;
                xmQhd = qel->next;
                if(!xmQhd) xmQtl = NULL;
        }
        spin_unlock_irqrestore(&txqueue_lock, flags);

        if ((debug & DEBUG_LOWER) && qel) {
                int n;
                printk(KERN_DEBUG "ltpc: dequeued command ");
                n = qel->cbuflen;
                if (n>100) n=100;
                for(i=0;i<n;i++) printk("%02x ",qel->cbuf[i]);
                printk("\n");
        }

        return qel;
}

/* and... the queue elements we'll be using */
static struct xmitQel qels[16];

/* and their corresponding mailboxes */
static unsigned char mailbox[16];
static unsigned char mboxinuse[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

static int wait_timeout(struct net_device *dev, int c)
{
        /* returns true if it stayed c */
        /* this uses base+6, but it's ok */
        int i;

        /* twenty second or so total */

        for(i=0;i<200000;i++) {
                if ( c != inb_p(dev->base_addr+6) ) return 0;
                udelay(100);
        }
        return 1; /* timed out */
}

/* get the first free mailbox */

static int getmbox(void)
{
        unsigned long flags;
        int i;

        spin_lock_irqsave(&mbox_lock, flags);
        for(i=1;i<16;i++) if(!mboxinuse[i]) {
                mboxinuse[i]=1;
                spin_unlock_irqrestore(&mbox_lock, flags);
                return i;
        }
        spin_unlock_irqrestore(&mbox_lock, flags);
        return 0;
}

/* read a command from the card */
static void handlefc(struct net_device *dev)
{
        /* called *only* from idle, non-reentrant */
        int dma = dev->dma;
        int base = dev->base_addr;
        unsigned long flags;


        flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_READ);
        set_dma_addr(dma,virt_to_bus(ltdmacbuf));
        set_dma_count(dma,50);
        enable_dma(dma);
        release_dma_lock(flags);

        inb_p(base+3);
        inb_p(base+2);

        if ( wait_timeout(dev,0xfc) ) printk("timed out in handlefc\n");
}

/* read data from the card */
static void handlefd(struct net_device *dev)
{
        int dma = dev->dma;
        int base = dev->base_addr;
        unsigned long flags;

        flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_READ);
        set_dma_addr(dma,virt_to_bus(ltdmabuf));
        set_dma_count(dma,800);
        enable_dma(dma);
        release_dma_lock(flags);

        inb_p(base+3);
        inb_p(base+2);

        if ( wait_timeout(dev,0xfd) ) printk("timed out in handlefd\n");
        sendup_buffer(dev);
} 

static void handlewrite(struct net_device *dev)
{
        /* called *only* from idle, non-reentrant */
        /* on entry, 0xfb and ltdmabuf holds data */
        int dma = dev->dma;
        int base = dev->base_addr;
        unsigned long flags;
        
        flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_WRITE);
        set_dma_addr(dma,virt_to_bus(ltdmabuf));
        set_dma_count(dma,800);
        enable_dma(dma);
        release_dma_lock(flags);
        
        inb_p(base+3);
        inb_p(base+2);

        if ( wait_timeout(dev,0xfb) ) {
                flags=claim_dma_lock();
                printk("timed out in handlewrite, dma res %d\n",
                        get_dma_residue(dev->dma) );
                release_dma_lock(flags);
        }
}

static void handleread(struct net_device *dev)
{
        /* on entry, 0xfb */
        /* on exit, ltdmabuf holds data */
        int dma = dev->dma;
        int base = dev->base_addr;
        unsigned long flags;

        
        flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_READ);
        set_dma_addr(dma,virt_to_bus(ltdmabuf));
        set_dma_count(dma,800);
        enable_dma(dma);
        release_dma_lock(flags);

        inb_p(base+3);
        inb_p(base+2);
        if ( wait_timeout(dev,0xfb) ) printk("timed out in handleread\n");
}

static void handlecommand(struct net_device *dev)
{
        /* on entry, 0xfa and ltdmacbuf holds command */
        int dma = dev->dma;
        int base = dev->base_addr;
        unsigned long flags;

        flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_WRITE);
        set_dma_addr(dma,virt_to_bus(ltdmacbuf));
        set_dma_count(dma,50);
        enable_dma(dma);
        release_dma_lock(flags);
        inb_p(base+3);
        inb_p(base+2);
        if ( wait_timeout(dev,0xfa) ) printk("timed out in handlecommand\n");
} 

/* ready made command for getting the result from the card */
static unsigned char rescbuf[2] = {LT_GETRESULT,0};
static unsigned char resdbuf[2];

static int QInIdle;

/* idle expects to be called with the IRQ line high -- either because of
 * an interrupt, or because the line is tri-stated
 */

static void idle(struct net_device *dev)
{
        unsigned long flags;
        int state;
        /* FIXME This is initialized to shut the warning up, but I need to
         * think this through again.
         */
        struct xmitQel *q = NULL;
        int oops;
        int i;
        int base = dev->base_addr;

        spin_lock_irqsave(&txqueue_lock, flags);
        if(QInIdle) {
                spin_unlock_irqrestore(&txqueue_lock, flags);
                return;
        }
        QInIdle = 1;
        spin_unlock_irqrestore(&txqueue_lock, flags);

        /* this tri-states the IRQ line */
        (void) inb_p(base+6);

        oops = 100;

loop:
        if (0>oops--) { 
                printk("idle: looped too many times\n");
                goto done;
        }

        state = inb_p(base+6);
        if (state != inb_p(base+6)) goto loop;

        switch(state) {
                case 0xfc:
                        /* incoming command */
                        if (debug & DEBUG_LOWER) printk("idle: fc\n");
                        handlefc(dev); 
                        break;
                case 0xfd:
                        /* incoming data */
                        if(debug & DEBUG_LOWER) printk("idle: fd\n");
                        handlefd(dev); 
                        break;
                case 0xf9:
                        /* result ready */
                        if (debug & DEBUG_LOWER) printk("idle: f9\n");
                        if(!mboxinuse[0]) {
                                mboxinuse[0] = 1;
                                qels[0].cbuf = rescbuf;
                                qels[0].cbuflen = 2;
                                qels[0].dbuf = resdbuf;
                                qels[0].dbuflen = 2;
                                qels[0].QWrite = 0;
                                qels[0].mailbox = 0;
                                enQ(&qels[0]);
                        }
                        inb_p(dev->base_addr+1);
                        inb_p(dev->base_addr+0);
                        if( wait_timeout(dev,0xf9) )
                                printk("timed out idle f9\n");
                        break;
                case 0xf8:
                        /* ?? */
                        if (xmQhd) {
                                inb_p(dev->base_addr+1);
                                inb_p(dev->base_addr+0);
                                if(wait_timeout(dev,0xf8) )
                                        printk("timed out idle f8\n");
                        } else {
                                goto done;
                        }
                        break;
                case 0xfa:
                        /* waiting for command */
                        if(debug & DEBUG_LOWER) printk("idle: fa\n");
                        if (xmQhd) {
                                q=deQ();
                                memcpy(ltdmacbuf,q->cbuf,q->cbuflen);
                                ltdmacbuf[1] = q->mailbox;
                                if (debug>1) { 
                                        int n;
                                        printk("ltpc: sent command     ");
                                        n = q->cbuflen;
                                        if (n>100) n=100;
                                        for(i=0;i<n;i++)
                                                printk("%02x ",ltdmacbuf[i]);
                                        printk("\n");
                                }
                                handlecommand(dev);
                                        if(0xfa==inb_p(base+6)) {
                                                /* we timed out, so return */
                                                goto done;
                                        } 
                        } else {
                                /* we don't seem to have a command */
                                if (!mboxinuse[0]) {
                                        mboxinuse[0] = 1;
                                        qels[0].cbuf = rescbuf;
                                        qels[0].cbuflen = 2;
                                        qels[0].dbuf = resdbuf;
                                        qels[0].dbuflen = 2;
                                        qels[0].QWrite = 0;
                                        qels[0].mailbox = 0;
                                        enQ(&qels[0]);
                                } else {
                                        printk("trouble: response command already queued\n");
                                        goto done;
                                }
                        } 
                        break;
                case 0Xfb:
                        /* data transfer ready */
                        if(debug & DEBUG_LOWER) printk("idle: fb\n");
                        if(q->QWrite) {
                                memcpy(ltdmabuf,q->dbuf,q->dbuflen);
                                handlewrite(dev);
                        } else {
                                handleread(dev);
                                /* non-zero mailbox numbers are for
                                   commmands, 0 is for GETRESULT
                                   requests */
                                if(q->mailbox) {
                                        memcpy(q->dbuf,ltdmabuf,q->dbuflen);
                                } else { 
                                        /* this was a result */
                                        mailbox[ 0x0f & ltdmabuf[0] ] = ltdmabuf[1];
                                        mboxinuse[0]=0;
                                }
                        }
                        break;
        }
        goto loop;

done:
        QInIdle=0;

        /* now set the interrupts back as appropriate */
        /* the first read takes it out of tri-state (but still high) */
        /* the second resets it */
        /* note that after this point, any read of base+6 will
           trigger an interrupt */

        if (dev->irq) {
                inb_p(base+7);
                inb_p(base+7);
        }
        return;
}


static int do_write(struct net_device *dev, void *cbuf, int cbuflen,
        void *dbuf, int dbuflen)
{

        int i = getmbox();
        int ret;

        if(i) {
                qels[i].cbuf = (unsigned char *) cbuf;
                qels[i].cbuflen = cbuflen;
                qels[i].dbuf = (unsigned char *) dbuf;
                qels[i].dbuflen = dbuflen;
                qels[i].QWrite = 1;
                qels[i].mailbox = i;  /* this should be initted rather */
                enQ(&qels[i]);
                idle(dev);
                ret = mailbox[i];
                mboxinuse[i]=0;
                return ret;
        }
        printk("ltpc: could not allocate mbox\n");
        return -1;
}

static int do_read(struct net_device *dev, void *cbuf, int cbuflen,
        void *dbuf, int dbuflen)
{

        int i = getmbox();
        int ret;

        if(i) {
                qels[i].cbuf = (unsigned char *) cbuf;
                qels[i].cbuflen = cbuflen;
                qels[i].dbuf = (unsigned char *) dbuf;
                qels[i].dbuflen = dbuflen;
                qels[i].QWrite = 0;
                qels[i].mailbox = i;  /* this should be initted rather */
                enQ(&qels[i]);
                idle(dev);
                ret = mailbox[i];
                mboxinuse[i]=0;
                return ret;
        }
        printk("ltpc: could not allocate mbox\n");
        return -1;
}

/* end of idle handlers -- what should be seen is do_read, do_write */

static struct timer_list ltpc_timer;

static int ltpc_xmit(struct sk_buff *skb, struct net_device *dev);
static struct net_device_stats *ltpc_get_stats(struct net_device *dev);

static int read_30 ( struct net_device *dev)
{
        lt_command c;
        c.getflags.command = LT_GETFLAGS;
        return do_read(dev, &c, sizeof(c.getflags),&c,0);
}

static int set_30 (struct net_device *dev,int x)
{
        lt_command c;
        c.setflags.command = LT_SETFLAGS;
        c.setflags.flags = x;
        return do_write(dev, &c, sizeof(c.setflags),&c,0);
}

/* LLAP to DDP translation */

static int sendup_buffer (struct net_device *dev)
{
        /* on entry, command is in ltdmacbuf, data in ltdmabuf */
        /* called from idle, non-reentrant */

        int dnode, snode, llaptype, len; 
        int sklen;
        struct sk_buff *skb;
        struct net_device_stats *stats = &((struct ltpc_private *)dev->priv)->stats;
        struct lt_rcvlap *ltc = (struct lt_rcvlap *) ltdmacbuf;

        if (ltc->command != LT_RCVLAP) {
                printk("unknown command 0x%02x from ltpc card\n",ltc->command);
                return(-1);
        }
        dnode = ltc->dnode;
        snode = ltc->snode;
        llaptype = ltc->laptype;
        len = ltc->length; 

        sklen = len;
        if (llaptype == 1) 
                sklen += 8;  /* correct for short ddp */
        if(sklen > 800) {
                printk(KERN_INFO "%s: nonsense length in ltpc command 0x14: 0x%08x\n",
                        dev->name,sklen);
                return -1;
        }

        if ( (llaptype==0) || (llaptype>2) ) {
                printk(KERN_INFO "%s: unknown LLAP type: %d\n",dev->name,llaptype);
                return -1;
        }


        skb = dev_alloc_skb(3+sklen);
        if (skb == NULL) 
        {
                printk("%s: dropping packet due to memory squeeze.\n",
                        dev->name);
                return -1;
        }
        skb->dev = dev;

        if (sklen > len)
                skb_reserve(skb,8);
        skb_put(skb,len+3);
        skb->protocol = htons(ETH_P_LOCALTALK);
        /* add LLAP header */
        skb->data[0] = dnode;
        skb->data[1] = snode;
        skb->data[2] = llaptype;
        skb_reset_mac_header(skb);      /* save pointer to llap header */
        skb_pull(skb,3);

        /* copy ddp(s,e)hdr + contents */
        skb_copy_to_linear_data(skb, ltdmabuf, len);

        skb_reset_transport_header(skb);

        stats->rx_packets++;
        stats->rx_bytes+=skb->len;

        /* toss it onwards */
        netif_rx(skb);
        dev->last_rx = jiffies;
        return 0;
}

/* the handler for the board interrupt */
 
static irqreturn_t
ltpc_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;

        if (dev==NULL) {
                printk("ltpc_interrupt: unknown device.\n");
                return IRQ_NONE;
        }

        inb_p(dev->base_addr+6);  /* disable further interrupts from board */

        idle(dev); /* handle whatever is coming in */
 
        /* idle re-enables interrupts from board */ 

        return IRQ_HANDLED;
}

/***
 *
 *    The ioctls that the driver responds to are:
 *
 *    SIOCSIFADDR -- do probe using the passed node hint.
 *    SIOCGIFADDR -- return net, node.
 *
 *    some of this stuff should be done elsewhere.
 *
 ***/

static int ltpc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        struct sockaddr_at *sa = (struct sockaddr_at *) &ifr->ifr_addr;
        /* we'll keep the localtalk node address in dev->pa_addr */
        struct atalk_addr *aa = &((struct ltpc_private *)dev->priv)->my_addr;
        struct lt_init c;
        int ltflags;

        if(debug & DEBUG_VERBOSE) printk("ltpc_ioctl called\n");

        switch(cmd) {
                case SIOCSIFADDR:

                        aa->s_net  = sa->sat_addr.s_net;
      
                        /* this does the probe and returns the node addr */
                        c.command = LT_INIT;
                        c.hint = sa->sat_addr.s_node;

                        aa->s_node = do_read(dev,&c,sizeof(c),&c,0);

                        /* get all llap frames raw */
                        ltflags = read_30(dev);
                        ltflags |= LT_FLAG_ALLLAP;
                        set_30 (dev,ltflags);  

                        dev->broadcast[0] = 0xFF;
                        dev->dev_addr[0] = aa->s_node;

                        dev->addr_len=1;
   
                        return 0;

                case SIOCGIFADDR:

                        sa->sat_addr.s_net = aa->s_net;
                        sa->sat_addr.s_node = aa->s_node;

                        return 0;

                default: 
                        return -EINVAL;
        }
}

static void set_multicast_list(struct net_device *dev)
{
        /* This needs to be present to keep netatalk happy. */
        /* Actually netatalk needs fixing! */
}

static int ltpc_poll_counter;

static void ltpc_poll(unsigned long l)
{
        struct net_device *dev = (struct net_device *) l;

        del_timer(&ltpc_timer);

        if(debug & DEBUG_VERBOSE) {
                if (!ltpc_poll_counter) {
                        ltpc_poll_counter = 50;
                        printk("ltpc poll is alive\n");
                }
                ltpc_poll_counter--;
        }
  
        if (!dev)
                return;  /* we've been downed */

        /* poll 20 times per second */
        idle(dev);
        ltpc_timer.expires = jiffies + HZ/20;
        
        add_timer(&ltpc_timer);
}

/* DDP to LLAP translation */

static int ltpc_xmit(struct sk_buff *skb, struct net_device *dev)
{
        /* in kernel 1.3.xx, on entry skb->data points to ddp header,
         * and skb->len is the length of the ddp data + ddp header
         */

        struct net_device_stats *stats = &((struct ltpc_private *)dev->priv)->stats;

        int i;
        struct lt_sendlap cbuf;
        unsigned char *hdr;

        cbuf.command = LT_SENDLAP;
        cbuf.dnode = skb->data[0];
        cbuf.laptype = skb->data[2];
        skb_pull(skb,3);        /* skip past LLAP header */
        cbuf.length = skb->len; /* this is host order */
        skb_reset_transport_header(skb);

        if(debug & DEBUG_UPPER) {
                printk("command ");
                for(i=0;i<6;i++)
                        printk("%02x ",((unsigned char *)&cbuf)[i]);
                printk("\n");
        }

        hdr = skb_transport_header(skb);
        do_write(dev, &cbuf, sizeof(cbuf), hdr, skb->len);

        if(debug & DEBUG_UPPER) {
                printk("sent %d ddp bytes\n",skb->len);
                for (i = 0; i < skb->len; i++)
                        printk("%02x ", hdr[i]);
                printk("\n");
        }

        stats->tx_packets++;
        stats->tx_bytes+=skb->len;

        dev_kfree_skb(skb);
        return 0;
}

static struct net_device_stats *ltpc_get_stats(struct net_device *dev)
{
        struct net_device_stats *stats = &((struct ltpc_private *) dev->priv)->stats;
        return stats;
}

/* initialization stuff */
  
static int __init ltpc_probe_dma(int base, int dma)
{
        int want = (dma == 3) ? 2 : (dma == 1) ? 1 : 3;
        unsigned long timeout;
        unsigned long f;
  
        if (want & 1) {
                if (request_dma(1,"ltpc")) {
                        want &= ~1;
                } else {
                        f=claim_dma_lock();
                        disable_dma(1);
                        clear_dma_ff(1);
                        set_dma_mode(1,DMA_MODE_WRITE);
                        set_dma_addr(1,virt_to_bus(ltdmabuf));
                        set_dma_count(1,sizeof(struct lt_mem));
                        enable_dma(1);
                        release_dma_lock(f);
                }
        }
        if (want & 2) {
                if (request_dma(3,"ltpc")) {
                        want &= ~2;
                } else {
                        f=claim_dma_lock();
                        disable_dma(3);
                        clear_dma_ff(3);
                        set_dma_mode(3,DMA_MODE_WRITE);
                        set_dma_addr(3,virt_to_bus(ltdmabuf));
                        set_dma_count(3,sizeof(struct lt_mem));
                        enable_dma(3);
                        release_dma_lock(f);
                }
        }
        /* set up request */

        /* FIXME -- do timings better! */

        ltdmabuf[0] = LT_READMEM;
        ltdmabuf[1] = 1;  /* mailbox */
        ltdmabuf[2] = 0; ltdmabuf[3] = 0;  /* address */
        ltdmabuf[4] = 0; ltdmabuf[5] = 1;  /* read 0x0100 bytes */
        ltdmabuf[6] = 0; /* dunno if this is necessary */

        inb_p(io+1);
        inb_p(io+0);
        timeout = jiffies+100*HZ/100;
        while(time_before(jiffies, timeout)) {
                if ( 0xfa == inb_p(io+6) ) break;
        }

        inb_p(io+3);
        inb_p(io+2);
        while(time_before(jiffies, timeout)) {
                if ( 0xfb == inb_p(io+6) ) break;
        }

        /* release the other dma channel (if we opened both of them) */

        if ((want & 2) && (get_dma_residue(3)==sizeof(struct lt_mem))) {
                want &= ~2;
                free_dma(3);
        }

        if ((want & 1) && (get_dma_residue(1)==sizeof(struct lt_mem))) {
                want &= ~1;
                free_dma(1);
        }

        if (!want)
                return 0;

        return (want & 2) ? 3 : 1;
}

struct net_device * __init ltpc_probe(void)
{
        struct net_device *dev;
        int err = -ENOMEM;
        int x=0,y=0;
        int autoirq;
        unsigned long f;
        unsigned long timeout;

        dev = alloc_ltalkdev(sizeof(struct ltpc_private));
        if (!dev)
                goto out;

        /* probe for the I/O port address */
        
        if (io != 0x240 && request_region(0x220,8,"ltpc")) {
                x = inb_p(0x220+6);
                if ( (x!=0xff) && (x>=0xf0) ) {
                        io = 0x220;
                        goto got_port;
                }
                release_region(0x220,8);
        }
        if (io != 0x220 && request_region(0x240,8,"ltpc")) {
                y = inb_p(0x240+6);
                if ( (y!=0xff) && (y>=0xf0) ){ 
                        io = 0x240;
                        goto got_port;
                }
                release_region(0x240,8);
        } 

        /* give up in despair */
        printk(KERN_ERR "LocalTalk card not found; 220 = %02x, 240 = %02x.\n", x,y);
        err = -ENODEV;
        goto out1;

 got_port:
        /* probe for the IRQ line */
        if (irq < 2) {
                unsigned long irq_mask;

                irq_mask = probe_irq_on();
                /* reset the interrupt line */
                inb_p(io+7);
                inb_p(io+7);
                /* trigger an interrupt (I hope) */
                inb_p(io+6);
                mdelay(2);
                autoirq = probe_irq_off(irq_mask);

                if (autoirq == 0) {
                        printk(KERN_ERR "ltpc: probe at %#x failed to detect IRQ line.\n", io);
                } else {
                        irq = autoirq;
                }
        }

        /* allocate a DMA buffer */
        ltdmabuf = (unsigned char *) dma_mem_alloc(1000);
        if (!ltdmabuf) {
                printk(KERN_ERR "ltpc: mem alloc failed\n");
                err = -ENOMEM;
                goto out2;
        }

        ltdmacbuf = &ltdmabuf[800];

        if(debug & DEBUG_VERBOSE) {
                printk("ltdmabuf pointer %08lx\n",(unsigned long) ltdmabuf);
        }

        /* reset the card */

        inb_p(io+1);
        inb_p(io+3);

        msleep(20);

        inb_p(io+0);
        inb_p(io+2);
        inb_p(io+7); /* clear reset */
        inb_p(io+4); 
        inb_p(io+5);
        inb_p(io+5); /* enable dma */
        inb_p(io+6); /* tri-state interrupt line */

        ssleep(1);
        
        /* now, figure out which dma channel we're using, unless it's
           already been specified */
        /* well, 0 is a legal DMA channel, but the LTPC card doesn't
           use it... */
        dma = ltpc_probe_dma(io, dma);
        if (!dma) {  /* no dma channel */
                printk(KERN_ERR "No DMA channel found on ltpc card.\n");
                err = -ENODEV;
                goto out3;
        }

        /* print out friendly message */
        if(irq)
                printk(KERN_INFO "Apple/Farallon LocalTalk-PC card at %03x, IR%d, DMA%d.\n",io,irq,dma);
        else
                printk(KERN_INFO "Apple/Farallon LocalTalk-PC card at %03x, DMA%d.  Using polled mode.\n",io,dma);

        /* Fill in the fields of the device structure with ethernet-generic values. */
        dev->hard_start_xmit = ltpc_xmit;
        dev->get_stats = ltpc_get_stats;

        /* add the ltpc-specific things */
        dev->do_ioctl = &ltpc_ioctl;

        dev->set_multicast_list = &set_multicast_list;
        dev->mc_list = NULL;
        dev->base_addr = io;
        dev->irq = irq;
        dev->dma = dma;

        /* the card will want to send a result at this point */
        /* (I think... leaving out this part makes the kernel crash,
           so I put it back in...) */

        f=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma,DMA_MODE_READ);
        set_dma_addr(dma,virt_to_bus(ltdmabuf));
        set_dma_count(dma,0x100);
        enable_dma(dma);
        release_dma_lock(f);

        (void) inb_p(io+3);
        (void) inb_p(io+2);
        timeout = jiffies+100*HZ/100;

        while(time_before(jiffies, timeout)) {
                if( 0xf9 == inb_p(io+6))
                        break;
                schedule();
        }

        if(debug & DEBUG_VERBOSE) {
                printk("setting up timer and irq\n");
        }

        /* grab it and don't let go :-) */
        if (irq && request_irq( irq, &ltpc_interrupt, 0, "ltpc", dev) >= 0)
        {
                (void) inb_p(io+7);  /* enable interrupts from board */
                (void) inb_p(io+7);  /* and reset irq line */
        } else {
                if( irq )
                        printk(KERN_ERR "ltpc: IRQ already in use, using polled mode.\n");
                dev->irq = 0;
                /* polled mode -- 20 times per second */
                /* this is really, really slow... should it poll more often? */
                init_timer(&ltpc_timer);
                ltpc_timer.function=ltpc_poll;
                ltpc_timer.data = (unsigned long) dev;

                ltpc_timer.expires = jiffies + HZ/20;
                add_timer(&ltpc_timer);
        }
        err = register_netdev(dev);
        if (err)
                goto out4;

        return NULL;
out4:
        del_timer_sync(&ltpc_timer);
        if (dev->irq)
                free_irq(dev->irq, dev);
out3:
        free_pages((unsigned long)ltdmabuf, get_order(1000));
out2:
        release_region(io, 8);
out1:
        free_netdev(dev);
out:
        return ERR_PTR(err);
}

#ifndef MODULE
/* handles "ltpc=io,irq,dma" kernel command lines */
static int __init ltpc_setup(char *str)
{
        int ints[5];

        str = get_options(str, ARRAY_SIZE(ints), ints);

        if (ints[0] == 0) {
                if (str && !strncmp(str, "auto", 4)) {
                        /* do nothing :-) */
                }
                else {
                        /* usage message */
                        printk (KERN_ERR
                                "ltpc: usage: ltpc=auto|iobase[,irq[,dma]]\n");
                        return 0;
                }
        } else {
                io = ints[1];
                if (ints[0] > 1) {
                        irq = ints[2];
                }
                if (ints[0] > 2) {
                        dma = ints[3];
                }
                /* ignore any other paramters */
        }
        return 1;
}

__setup("ltpc=", ltpc_setup);
#endif /* MODULE */

static struct net_device *dev_ltpc;

#ifdef MODULE

MODULE_LICENSE("GPL");
module_param(debug, int, 0);
module_param(io, int, 0);
module_param(irq, int, 0);
module_param(dma, int, 0);


int __init init_module(void)
{
        if(io == 0)
                printk(KERN_NOTICE
                       "ltpc: Autoprobing is not recommended for modules\n");

        dev_ltpc = ltpc_probe();
        if (IS_ERR(dev_ltpc))
                return PTR_ERR(dev_ltpc);
        return 0;
}
#endif

static void __exit ltpc_cleanup(void)
{

        if(debug & DEBUG_VERBOSE) printk("unregister_netdev\n");
        unregister_netdev(dev_ltpc);

        ltpc_timer.data = 0;  /* signal the poll routine that we're done */

        del_timer_sync(&ltpc_timer);

        if(debug & DEBUG_VERBOSE) printk("freeing irq\n");

        if (dev_ltpc->irq)
                free_irq(dev_ltpc->irq, dev_ltpc);

        if(debug & DEBUG_VERBOSE) printk("freeing dma\n");

        if (dev_ltpc->dma)
                free_dma(dev_ltpc->dma);

        if(debug & DEBUG_VERBOSE) printk("freeing ioaddr\n");

        if (dev_ltpc->base_addr)
                release_region(dev_ltpc->base_addr,8);

        free_netdev(dev_ltpc);

        if(debug & DEBUG_VERBOSE) printk("free_pages\n");

        free_pages( (unsigned long) ltdmabuf, get_order(1000));

        if(debug & DEBUG_VERBOSE) printk("returning from cleanup_module\n");
}

module_exit(ltpc_cleanup);