Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1793 insertions, 0 deletions

diff --git a/drivers/net/wan/z85230.c b/drivers/net/wan/z85230.c
new file mode 100644
index 000000000..deea41e96
--- /dev/null
+++ b/drivers/net/wan/z85230.c
@@ -0,0 +1,1793 @@
+/*
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *	(c) Copyright 1998 Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *	(c) Copyright 2000, 2001 Red Hat Inc
+ *
+ *	Development of this driver was funded by Equiinet Ltd
+ *			http://www.equiinet.com
+ *
+ *	ChangeLog:
+ *
+ *	Asynchronous mode dropped for 2.2. For 2.5 we will attempt the
+ *	unification of all the Z85x30 asynchronous drivers for real.
+ *
+ *	DMA now uses get_free_page as kmalloc buffers may span a 64K 
+ *	boundary.
+ *
+ *	Modified for SMP safety and SMP locking by Alan Cox
+ *					<alan@lxorguk.ukuu.org.uk>
+ *
+ *	Performance
+ *
+ *	Z85230:
+ *	Non DMA you want a 486DX50 or better to do 64Kbits. 9600 baud
+ *	X.25 is not unrealistic on all machines. DMA mode can in theory
+ *	handle T1/E1 quite nicely. In practice the limit seems to be about
+ *	512Kbit->1Mbit depending on motherboard.
+ *
+ *	Z85C30:
+ *	64K will take DMA, 9600 baud X.25 should be ok.
+ *
+ *	Z8530:
+ *	Synchronous mode without DMA is unlikely to pass about 2400 baud.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/delay.h>
+#include <linux/hdlc.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <asm/dma.h>
+#include <asm/io.h>
+#define RT_LOCK
+#define RT_UNLOCK
+#include <linux/spinlock.h>
+
+#include "z85230.h"
+
+
+/**
+ *	z8530_read_port - Architecture specific interface function
+ *	@p: port to read
+ *
+ *	Provided port access methods. The Comtrol SV11 requires no delays
+ *	between accesses and uses PC I/O. Some drivers may need a 5uS delay
+ *	
+ *	In the longer term this should become an architecture specific
+ *	section so that this can become a generic driver interface for all
+ *	platforms. For now we only handle PC I/O ports with or without the
+ *	dread 5uS sanity delay.
+ *
+ *	The caller must hold sufficient locks to avoid violating the horrible
+ *	5uS delay rule.
+ */
+
+static inline int z8530_read_port(unsigned long p)
+{
+	u8 r=inb(Z8530_PORT_OF(p));
+	if(p&Z8530_PORT_SLEEP)	/* gcc should figure this out efficiently ! */
+		udelay(5);
+	return r;
+}
+
+/**
+ *	z8530_write_port - Architecture specific interface function
+ *	@p: port to write
+ *	@d: value to write
+ *
+ *	Write a value to a port with delays if need be. Note that the
+ *	caller must hold locks to avoid read/writes from other contexts
+ *	violating the 5uS rule
+ *
+ *	In the longer term this should become an architecture specific
+ *	section so that this can become a generic driver interface for all
+ *	platforms. For now we only handle PC I/O ports with or without the
+ *	dread 5uS sanity delay.
+ */
+
+
+static inline void z8530_write_port(unsigned long p, u8 d)
+{
+	outb(d,Z8530_PORT_OF(p));
+	if(p&Z8530_PORT_SLEEP)
+		udelay(5);
+}
+
+
+
+static void z8530_rx_done(struct z8530_channel *c);
+static void z8530_tx_done(struct z8530_channel *c);
+
+
+/**
+ *	read_zsreg - Read a register from a Z85230 
+ *	@c: Z8530 channel to read from (2 per chip)
+ *	@reg: Register to read
+ *	FIXME: Use a spinlock.
+ *	
+ *	Most of the Z8530 registers are indexed off the control registers.
+ *	A read is done by writing to the control register and reading the
+ *	register back.  The caller must hold the lock
+ */
+ 
+static inline u8 read_zsreg(struct z8530_channel *c, u8 reg)
+{
+	if(reg)
+		z8530_write_port(c->ctrlio, reg);
+	return z8530_read_port(c->ctrlio);
+}
+
+/**
+ *	read_zsdata - Read the data port of a Z8530 channel
+ *	@c: The Z8530 channel to read the data port from
+ *
+ *	The data port provides fast access to some things. We still
+ *	have all the 5uS delays to worry about.
+ */
+
+static inline u8 read_zsdata(struct z8530_channel *c)
+{
+	u8 r;
+	r=z8530_read_port(c->dataio);
+	return r;
+}
+
+/**
+ *	write_zsreg - Write to a Z8530 channel register
+ *	@c: The Z8530 channel
+ *	@reg: Register number
+ *	@val: Value to write
+ *
+ *	Write a value to an indexed register. The caller must hold the lock
+ *	to honour the irritating delay rules. We know about register 0
+ *	being fast to access.
+ *
+ *      Assumes c->lock is held.
+ */
+static inline void write_zsreg(struct z8530_channel *c, u8 reg, u8 val)
+{
+	if(reg)
+		z8530_write_port(c->ctrlio, reg);
+	z8530_write_port(c->ctrlio, val);
+
+}
+
+/**
+ *	write_zsctrl - Write to a Z8530 control register
+ *	@c: The Z8530 channel
+ *	@val: Value to write
+ *
+ *	Write directly to the control register on the Z8530
+ */
+
+static inline void write_zsctrl(struct z8530_channel *c, u8 val)
+{
+	z8530_write_port(c->ctrlio, val);
+}
+
+/**
+ *	write_zsdata - Write to a Z8530 control register
+ *	@c: The Z8530 channel
+ *	@val: Value to write
+ *
+ *	Write directly to the data register on the Z8530
+ */
+
+
+static inline void write_zsdata(struct z8530_channel *c, u8 val)
+{
+	z8530_write_port(c->dataio, val);
+}
+
+/*
+ *	Register loading parameters for a dead port
+ */
+ 
+u8 z8530_dead_port[]=
+{
+	255
+};
+
+EXPORT_SYMBOL(z8530_dead_port);
+
+/*
+ *	Register loading parameters for currently supported circuit types
+ */
+
+
+/*
+ *	Data clocked by telco end. This is the correct data for the UK
+ *	"kilostream" service, and most other similar services.
+ */
+ 
+u8 z8530_hdlc_kilostream[]=
+{
+	4,	SYNC_ENAB|SDLC|X1CLK,
+	2,	0,	/* No vector */
+	1,	0,
+	3,	ENT_HM|RxCRC_ENAB|Rx8,
+	5,	TxCRC_ENAB|RTS|TxENAB|Tx8|DTR,
+	9,	0,		/* Disable interrupts */
+	6,	0xFF,
+	7,	FLAG,
+	10,	ABUNDER|NRZ|CRCPS,/*MARKIDLE ??*/
+	11,	TCTRxCP,
+	14,	DISDPLL,
+	15,	DCDIE|SYNCIE|CTSIE|TxUIE|BRKIE,
+	1,	EXT_INT_ENAB|TxINT_ENAB|INT_ALL_Rx,
+	9,	NV|MIE|NORESET,
+	255
+};
+
+EXPORT_SYMBOL(z8530_hdlc_kilostream);
+
+/*
+ *	As above but for enhanced chips.
+ */
+ 
+u8 z8530_hdlc_kilostream_85230[]=
+{
+	4,	SYNC_ENAB|SDLC|X1CLK,
+	2,	0,	/* No vector */
+	1,	0,
+	3,	ENT_HM|RxCRC_ENAB|Rx8,
+	5,	TxCRC_ENAB|RTS|TxENAB|Tx8|DTR,
+	9,	0,		/* Disable interrupts */
+	6,	0xFF,
+	7,	FLAG,
+	10,	ABUNDER|NRZ|CRCPS,	/* MARKIDLE?? */
+	11,	TCTRxCP,
+	14,	DISDPLL,
+	15,	DCDIE|SYNCIE|CTSIE|TxUIE|BRKIE,
+	1,	EXT_INT_ENAB|TxINT_ENAB|INT_ALL_Rx,
+	9,	NV|MIE|NORESET,
+	23,	3,		/* Extended mode AUTO TX and EOM*/
+	
+	255
+};
+
+EXPORT_SYMBOL(z8530_hdlc_kilostream_85230);
+
+/**
+ *	z8530_flush_fifo - Flush on chip RX FIFO
+ *	@c: Channel to flush
+ *
+ *	Flush the receive FIFO. There is no specific option for this, we 
+ *	blindly read bytes and discard them. Reading when there is no data
+ *	is harmless. The 8530 has a 4 byte FIFO, the 85230 has 8 bytes.
+ *	
+ *	All locking is handled for the caller. On return data may still be
+ *	present if it arrived during the flush.
+ */
+ 
+static void z8530_flush_fifo(struct z8530_channel *c)
+{
+	read_zsreg(c, R1);
+	read_zsreg(c, R1);
+	read_zsreg(c, R1);
+	read_zsreg(c, R1);
+	if(c->dev->type==Z85230)
+	{
+		read_zsreg(c, R1);
+		read_zsreg(c, R1);
+		read_zsreg(c, R1);
+		read_zsreg(c, R1);
+	}
+}	
+
+/**
+ *	z8530_rtsdtr - Control the outgoing DTS/RTS line
+ *	@c: The Z8530 channel to control;
+ *	@set: 1 to set, 0 to clear
+ *
+ *	Sets or clears DTR/RTS on the requested line. All locking is handled
+ *	by the caller. For now we assume all boards use the actual RTS/DTR
+ *	on the chip. Apparently one or two don't. We'll scream about them
+ *	later.
+ */
+
+static void z8530_rtsdtr(struct z8530_channel *c, int set)
+{
+	if (set)
+		c->regs[5] |= (RTS | DTR);
+	else
+		c->regs[5] &= ~(RTS | DTR);
+	write_zsreg(c, R5, c->regs[5]);
+}
+
+/**
+ *	z8530_rx - Handle a PIO receive event
+ *	@c: Z8530 channel to process
+ *
+ *	Receive handler for receiving in PIO mode. This is much like the 
+ *	async one but not quite the same or as complex
+ *
+ *	Note: Its intended that this handler can easily be separated from
+ *	the main code to run realtime. That'll be needed for some machines
+ *	(eg to ever clock 64kbits on a sparc ;)).
+ *
+ *	The RT_LOCK macros don't do anything now. Keep the code covered
+ *	by them as short as possible in all circumstances - clocks cost
+ *	baud. The interrupt handler is assumed to be atomic w.r.t. to
+ *	other code - this is true in the RT case too.
+ *
+ *	We only cover the sync cases for this. If you want 2Mbit async
+ *	do it yourself but consider medical assistance first. This non DMA 
+ *	synchronous mode is portable code. The DMA mode assumes PCI like 
+ *	ISA DMA
+ *
+ *	Called with the device lock held
+ */
+ 
+static void z8530_rx(struct z8530_channel *c)
+{
+	u8 ch,stat;
+
+	while(1)
+	{
+		/* FIFO empty ? */
+		if(!(read_zsreg(c, R0)&1))
+			break;
+		ch=read_zsdata(c);
+		stat=read_zsreg(c, R1);
+	
+		/*
+		 *	Overrun ?
+		 */
+		if(c->count < c->max)
+		{
+			*c->dptr++=ch;
+			c->count++;
+		}
+
+		if(stat&END_FR)
+		{
+		
+			/*
+			 *	Error ?
+			 */
+			if(stat&(Rx_OVR|CRC_ERR))
+			{
+				/* Rewind the buffer and return */
+				if(c->skb)
+					c->dptr=c->skb->data;
+				c->count=0;
+				if(stat&Rx_OVR)
+				{
+					pr_warn("%s: overrun\n", c->dev->name);
+					c->rx_overrun++;
+				}
+				if(stat&CRC_ERR)
+				{
+					c->rx_crc_err++;
+					/* printk("crc error\n"); */
+				}
+				/* Shove the frame upstream */
+			}
+			else
+			{
+				/*
+				 *	Drop the lock for RX processing, or
+		 		 *	there are deadlocks
+		 		 */
+				z8530_rx_done(c);
+				write_zsctrl(c, RES_Rx_CRC);
+			}
+		}
+	}
+	/*
+	 *	Clear irq
+	 */
+	write_zsctrl(c, ERR_RES);
+	write_zsctrl(c, RES_H_IUS);
+}
+
+
+/**
+ *	z8530_tx - Handle a PIO transmit event
+ *	@c: Z8530 channel to process
+ *
+ *	Z8530 transmit interrupt handler for the PIO mode. The basic
+ *	idea is to attempt to keep the FIFO fed. We fill as many bytes
+ *	in as possible, its quite possible that we won't keep up with the
+ *	data rate otherwise.
+ */
+ 
+static void z8530_tx(struct z8530_channel *c)
+{
+	while(c->txcount) {
+		/* FIFO full ? */
+		if(!(read_zsreg(c, R0)&4))
+			return;
+		c->txcount--;
+		/*
+		 *	Shovel out the byte
+		 */
+		write_zsreg(c, R8, *c->tx_ptr++);
+		write_zsctrl(c, RES_H_IUS);
+		/* We are about to underflow */
+		if(c->txcount==0)
+		{
+			write_zsctrl(c, RES_EOM_L);
+			write_zsreg(c, R10, c->regs[10]&~ABUNDER);
+		}
+	}
+
+	
+	/*
+	 *	End of frame TX - fire another one
+	 */
+	 
+	write_zsctrl(c, RES_Tx_P);
+
+	z8530_tx_done(c);	 
+	write_zsctrl(c, RES_H_IUS);
+}
+
+/**
+ *	z8530_status - Handle a PIO status exception
+ *	@chan: Z8530 channel to process
+ *
+ *	A status event occurred in PIO synchronous mode. There are several
+ *	reasons the chip will bother us here. A transmit underrun means we
+ *	failed to feed the chip fast enough and just broke a packet. A DCD
+ *	change is a line up or down.
+ */
+
+static void z8530_status(struct z8530_channel *chan)
+{
+	u8 status, altered;
+
+	status = read_zsreg(chan, R0);
+	altered = chan->status ^ status;
+
+	chan->status = status;
+
+	if (status & TxEOM) {
+/*		printk("%s: Tx underrun.\n", chan->dev->name); */
+		chan->netdevice->stats.tx_fifo_errors++;
+		write_zsctrl(chan, ERR_RES);
+		z8530_tx_done(chan);
+	}
+
+	if (altered & chan->dcdcheck)
+	{
+		if (status & chan->dcdcheck) {
+			pr_info("%s: DCD raised\n", chan->dev->name);
+			write_zsreg(chan, R3, chan->regs[3] | RxENABLE);
+			if (chan->netdevice)
+				netif_carrier_on(chan->netdevice);
+		} else {
+			pr_info("%s: DCD lost\n", chan->dev->name);
+			write_zsreg(chan, R3, chan->regs[3] & ~RxENABLE);
+			z8530_flush_fifo(chan);
+			if (chan->netdevice)
+				netif_carrier_off(chan->netdevice);
+		}
+
+	}
+	write_zsctrl(chan, RES_EXT_INT);
+	write_zsctrl(chan, RES_H_IUS);
+}
+
+struct z8530_irqhandler z8530_sync = {
+	.rx = z8530_rx,
+	.tx = z8530_tx,
+	.status = z8530_status,
+};
+
+EXPORT_SYMBOL(z8530_sync);
+
+/**
+ *	z8530_dma_rx - Handle a DMA RX event
+ *	@chan: Channel to handle
+ *
+ *	Non bus mastering DMA interfaces for the Z8x30 devices. This
+ *	is really pretty PC specific. The DMA mode means that most receive
+ *	events are handled by the DMA hardware. We get a kick here only if
+ *	a frame ended.
+ */
+ 
+static void z8530_dma_rx(struct z8530_channel *chan)
+{
+	if(chan->rxdma_on)
+	{
+		/* Special condition check only */
+		u8 status;
+	
+		read_zsreg(chan, R7);
+		read_zsreg(chan, R6);
+		
+		status=read_zsreg(chan, R1);
+	
+		if(status&END_FR)
+		{
+			z8530_rx_done(chan);	/* Fire up the next one */
+		}		
+		write_zsctrl(chan, ERR_RES);
+		write_zsctrl(chan, RES_H_IUS);
+	}
+	else
+	{
+		/* DMA is off right now, drain the slow way */
+		z8530_rx(chan);
+	}	
+}
+
+/**
+ *	z8530_dma_tx - Handle a DMA TX event
+ *	@chan:	The Z8530 channel to handle
+ *
+ *	We have received an interrupt while doing DMA transmissions. It
+ *	shouldn't happen. Scream loudly if it does.
+ */
+ 
+static void z8530_dma_tx(struct z8530_channel *chan)
+{
+	if(!chan->dma_tx)
+	{
+		pr_warn("Hey who turned the DMA off?\n");
+		z8530_tx(chan);
+		return;
+	}
+	/* This shouldn't occur in DMA mode */
+	pr_err("DMA tx - bogus event!\n");
+	z8530_tx(chan);
+}
+
+/**
+ *	z8530_dma_status - Handle a DMA status exception
+ *	@chan: Z8530 channel to process
+ *	
+ *	A status event occurred on the Z8530. We receive these for two reasons
+ *	when in DMA mode. Firstly if we finished a packet transfer we get one
+ *	and kick the next packet out. Secondly we may see a DCD change.
+ *
+ */
+ 
+static void z8530_dma_status(struct z8530_channel *chan)
+{
+	u8 status, altered;
+
+	status=read_zsreg(chan, R0);
+	altered=chan->status^status;
+	
+	chan->status=status;
+
+
+	if(chan->dma_tx)
+	{
+		if(status&TxEOM)
+		{
+			unsigned long flags;
+	
+			flags=claim_dma_lock();
+			disable_dma(chan->txdma);
+			clear_dma_ff(chan->txdma);	
+			chan->txdma_on=0;
+			release_dma_lock(flags);
+			z8530_tx_done(chan);
+		}
+	}
+
+	if (altered & chan->dcdcheck)
+	{
+		if (status & chan->dcdcheck) {
+			pr_info("%s: DCD raised\n", chan->dev->name);
+			write_zsreg(chan, R3, chan->regs[3] | RxENABLE);
+			if (chan->netdevice)
+				netif_carrier_on(chan->netdevice);
+		} else {
+			pr_info("%s: DCD lost\n", chan->dev->name);
+			write_zsreg(chan, R3, chan->regs[3] & ~RxENABLE);
+			z8530_flush_fifo(chan);
+			if (chan->netdevice)
+				netif_carrier_off(chan->netdevice);
+		}
+	}
+
+	write_zsctrl(chan, RES_EXT_INT);
+	write_zsctrl(chan, RES_H_IUS);
+}
+
+static struct z8530_irqhandler z8530_dma_sync = {
+	.rx = z8530_dma_rx,
+	.tx = z8530_dma_tx,
+	.status = z8530_dma_status,
+};
+
+static struct z8530_irqhandler z8530_txdma_sync = {
+	.rx = z8530_rx,
+	.tx = z8530_dma_tx,
+	.status = z8530_dma_status,
+};
+
+/**
+ *	z8530_rx_clear - Handle RX events from a stopped chip
+ *	@c: Z8530 channel to shut up
+ *
+ *	Receive interrupt vectors for a Z8530 that is in 'parked' mode.
+ *	For machines with PCI Z85x30 cards, or level triggered interrupts
+ *	(eg the MacII) we must clear the interrupt cause or die.
+ */
+
+
+static void z8530_rx_clear(struct z8530_channel *c)
+{
+	/*
+	 *	Data and status bytes
+	 */
+	u8 stat;
+
+	read_zsdata(c);
+	stat=read_zsreg(c, R1);
+	
+	if(stat&END_FR)
+		write_zsctrl(c, RES_Rx_CRC);
+	/*
+	 *	Clear irq
+	 */
+	write_zsctrl(c, ERR_RES);
+	write_zsctrl(c, RES_H_IUS);
+}
+
+/**
+ *	z8530_tx_clear - Handle TX events from a stopped chip
+ *	@c: Z8530 channel to shut up
+ *
+ *	Transmit interrupt vectors for a Z8530 that is in 'parked' mode.
+ *	For machines with PCI Z85x30 cards, or level triggered interrupts
+ *	(eg the MacII) we must clear the interrupt cause or die.
+ */
+
+static void z8530_tx_clear(struct z8530_channel *c)
+{
+	write_zsctrl(c, RES_Tx_P);
+	write_zsctrl(c, RES_H_IUS);
+}
+
+/**
+ *	z8530_status_clear - Handle status events from a stopped chip
+ *	@chan: Z8530 channel to shut up
+ *
+ *	Status interrupt vectors for a Z8530 that is in 'parked' mode.
+ *	For machines with PCI Z85x30 cards, or level triggered interrupts
+ *	(eg the MacII) we must clear the interrupt cause or die.
+ */
+
+static void z8530_status_clear(struct z8530_channel *chan)
+{
+	u8 status=read_zsreg(chan, R0);
+	if(status&TxEOM)
+		write_zsctrl(chan, ERR_RES);
+	write_zsctrl(chan, RES_EXT_INT);
+	write_zsctrl(chan, RES_H_IUS);
+}
+
+struct z8530_irqhandler z8530_nop = {
+	.rx = z8530_rx_clear,
+	.tx = z8530_tx_clear,
+	.status = z8530_status_clear,
+};
+
+
+EXPORT_SYMBOL(z8530_nop);
+
+/**
+ *	z8530_interrupt - Handle an interrupt from a Z8530
+ *	@irq: 	Interrupt number
+ *	@dev_id: The Z8530 device that is interrupting.
+ *
+ *	A Z85[2]30 device has stuck its hand in the air for attention.
+ *	We scan both the channels on the chip for events and then call
+ *	the channel specific call backs for each channel that has events.
+ *	We have to use callback functions because the two channels can be
+ *	in different modes.
+ *
+ *	Locking is done for the handlers. Note that locking is done
+ *	at the chip level (the 5uS delay issue is per chip not per
+ *	channel). c->lock for both channels points to dev->lock
+ */
+
+irqreturn_t z8530_interrupt(int irq, void *dev_id)
+{
+	struct z8530_dev *dev=dev_id;
+	u8 uninitialized_var(intr);
+	static volatile int locker=0;
+	int work=0;
+	struct z8530_irqhandler *irqs;
+	
+	if(locker)
+	{
+		pr_err("IRQ re-enter\n");
+		return IRQ_NONE;
+	}
+	locker=1;
+
+	spin_lock(&dev->lock);
+
+	while(++work<5000)
+	{
+
+		intr = read_zsreg(&dev->chanA, R3);
+		if(!(intr & (CHARxIP|CHATxIP|CHAEXT|CHBRxIP|CHBTxIP|CHBEXT)))
+			break;
+	
+		/* This holds the IRQ status. On the 8530 you must read it from chan 
+		   A even though it applies to the whole chip */
+		
+		/* Now walk the chip and see what it is wanting - it may be
+		   an IRQ for someone else remember */
+		   
+		irqs=dev->chanA.irqs;
+
+		if(intr & (CHARxIP|CHATxIP|CHAEXT))
+		{
+			if(intr&CHARxIP)
+				irqs->rx(&dev->chanA);
+			if(intr&CHATxIP)
+				irqs->tx(&dev->chanA);
+			if(intr&CHAEXT)
+				irqs->status(&dev->chanA);
+		}
+
+		irqs=dev->chanB.irqs;
+
+		if(intr & (CHBRxIP|CHBTxIP|CHBEXT))
+		{
+			if(intr&CHBRxIP)
+				irqs->rx(&dev->chanB);
+			if(intr&CHBTxIP)
+				irqs->tx(&dev->chanB);
+			if(intr&CHBEXT)
+				irqs->status(&dev->chanB);
+		}
+	}
+	spin_unlock(&dev->lock);
+	if(work==5000)
+		pr_err("%s: interrupt jammed - abort(0x%X)!\n",
+		       dev->name, intr);
+	/* Ok all done */
+	locker=0;
+	return IRQ_HANDLED;
+}
+
+EXPORT_SYMBOL(z8530_interrupt);
+
+static const u8 reg_init[16]=
+{
+	0,0,0,0,
+	0,0,0,0,
+	0,0,0,0,
+	0x55,0,0,0
+};
+
+
+/**
+ *	z8530_sync_open - Open a Z8530 channel for PIO
+ *	@dev:	The network interface we are using
+ *	@c:	The Z8530 channel to open in synchronous PIO mode
+ *
+ *	Switch a Z8530 into synchronous mode without DMA assist. We
+ *	raise the RTS/DTR and commence network operation.
+ */
+ 
+int z8530_sync_open(struct net_device *dev, struct z8530_channel *c)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(c->lock, flags);
+
+	c->sync = 1;
+	c->mtu = dev->mtu+64;
+	c->count = 0;
+	c->skb = NULL;
+	c->skb2 = NULL;
+	c->irqs = &z8530_sync;
+
+	/* This loads the double buffer up */
+	z8530_rx_done(c);	/* Load the frame ring */
+	z8530_rx_done(c);	/* Load the backup frame */
+	z8530_rtsdtr(c,1);
+	c->dma_tx = 0;
+	c->regs[R1]|=TxINT_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);
+	write_zsreg(c, R3, c->regs[R3]|RxENABLE);
+
+	spin_unlock_irqrestore(c->lock, flags);
+	return 0;
+}
+
+
+EXPORT_SYMBOL(z8530_sync_open);
+
+/**
+ *	z8530_sync_close - Close a PIO Z8530 channel
+ *	@dev: Network device to close
+ *	@c: Z8530 channel to disassociate and move to idle
+ *
+ *	Close down a Z8530 interface and switch its interrupt handlers
+ *	to discard future events.
+ */
+ 
+int z8530_sync_close(struct net_device *dev, struct z8530_channel *c)
+{
+	u8 chk;
+	unsigned long flags;
+	
+	spin_lock_irqsave(c->lock, flags);
+	c->irqs = &z8530_nop;
+	c->max = 0;
+	c->sync = 0;
+	
+	chk=read_zsreg(c,R0);
+	write_zsreg(c, R3, c->regs[R3]);
+	z8530_rtsdtr(c,0);
+
+	spin_unlock_irqrestore(c->lock, flags);
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_sync_close);
+
+/**
+ *	z8530_sync_dma_open - Open a Z8530 for DMA I/O
+ *	@dev: The network device to attach
+ *	@c: The Z8530 channel to configure in sync DMA mode.
+ *
+ *	Set up a Z85x30 device for synchronous DMA in both directions. Two
+ *	ISA DMA channels must be available for this to work. We assume ISA
+ *	DMA driven I/O and PC limits on access.
+ */
+ 
+int z8530_sync_dma_open(struct net_device *dev, struct z8530_channel *c)
+{
+	unsigned long cflags, dflags;
+	
+	c->sync = 1;
+	c->mtu = dev->mtu+64;
+	c->count = 0;
+	c->skb = NULL;
+	c->skb2 = NULL;
+	/*
+	 *	Load the DMA interfaces up
+	 */
+	c->rxdma_on = 0;
+	c->txdma_on = 0;
+	
+	/*
+	 *	Allocate the DMA flip buffers. Limit by page size.
+	 *	Everyone runs 1500 mtu or less on wan links so this
+	 *	should be fine.
+	 */
+	 
+	if(c->mtu  > PAGE_SIZE/2)
+		return -EMSGSIZE;
+	 
+	c->rx_buf[0]=(void *)get_zeroed_page(GFP_KERNEL|GFP_DMA);
+	if(c->rx_buf[0]==NULL)
+		return -ENOBUFS;
+	c->rx_buf[1]=c->rx_buf[0]+PAGE_SIZE/2;
+	
+	c->tx_dma_buf[0]=(void *)get_zeroed_page(GFP_KERNEL|GFP_DMA);
+	if(c->tx_dma_buf[0]==NULL)
+	{
+		free_page((unsigned long)c->rx_buf[0]);
+		c->rx_buf[0]=NULL;
+		return -ENOBUFS;
+	}
+	c->tx_dma_buf[1]=c->tx_dma_buf[0]+PAGE_SIZE/2;
+
+	c->tx_dma_used=0;
+	c->dma_tx = 1;
+	c->dma_num=0;
+	c->dma_ready=1;
+	
+	/*
+	 *	Enable DMA control mode
+	 */
+
+	spin_lock_irqsave(c->lock, cflags);
+	 
+	/*
+	 *	TX DMA via DIR/REQ
+	 */
+	 
+	c->regs[R14]|= DTRREQ;
+	write_zsreg(c, R14, c->regs[R14]);     
+
+	c->regs[R1]&= ~TxINT_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);
+	
+	/*
+	 *	RX DMA via W/Req
+	 */	 
+
+	c->regs[R1]|= WT_FN_RDYFN;
+	c->regs[R1]|= WT_RDY_RT;
+	c->regs[R1]|= INT_ERR_Rx;
+	c->regs[R1]&= ~TxINT_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);
+	c->regs[R1]|= WT_RDY_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);            
+	
+	/*
+	 *	DMA interrupts
+	 */
+	 
+	/*
+	 *	Set up the DMA configuration
+	 */	
+	 
+	dflags=claim_dma_lock();
+	 
+	disable_dma(c->rxdma);
+	clear_dma_ff(c->rxdma);
+	set_dma_mode(c->rxdma, DMA_MODE_READ|0x10);
+	set_dma_addr(c->rxdma, virt_to_bus(c->rx_buf[0]));
+	set_dma_count(c->rxdma, c->mtu);
+	enable_dma(c->rxdma);
+
+	disable_dma(c->txdma);
+	clear_dma_ff(c->txdma);
+	set_dma_mode(c->txdma, DMA_MODE_WRITE);
+	disable_dma(c->txdma);
+	
+	release_dma_lock(dflags);
+	
+	/*
+	 *	Select the DMA interrupt handlers
+	 */
+
+	c->rxdma_on = 1;
+	c->txdma_on = 1;
+	c->tx_dma_used = 1;
+	 
+	c->irqs = &z8530_dma_sync;
+	z8530_rtsdtr(c,1);
+	write_zsreg(c, R3, c->regs[R3]|RxENABLE);
+
+	spin_unlock_irqrestore(c->lock, cflags);
+	
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_sync_dma_open);
+
+/**
+ *	z8530_sync_dma_close - Close down DMA I/O
+ *	@dev: Network device to detach
+ *	@c: Z8530 channel to move into discard mode
+ *
+ *	Shut down a DMA mode synchronous interface. Halt the DMA, and
+ *	free the buffers.
+ */
+ 
+int z8530_sync_dma_close(struct net_device *dev, struct z8530_channel *c)
+{
+	u8 chk;
+	unsigned long flags;
+	
+	c->irqs = &z8530_nop;
+	c->max = 0;
+	c->sync = 0;
+	
+	/*
+	 *	Disable the PC DMA channels
+	 */
+	
+	flags=claim_dma_lock(); 
+	disable_dma(c->rxdma);
+	clear_dma_ff(c->rxdma);
+	
+	c->rxdma_on = 0;
+	
+	disable_dma(c->txdma);
+	clear_dma_ff(c->txdma);
+	release_dma_lock(flags);
+	
+	c->txdma_on = 0;
+	c->tx_dma_used = 0;
+
+	spin_lock_irqsave(c->lock, flags);
+
+	/*
+	 *	Disable DMA control mode
+	 */
+	 
+	c->regs[R1]&= ~WT_RDY_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);            
+	c->regs[R1]&= ~(WT_RDY_RT|WT_FN_RDYFN|INT_ERR_Rx);
+	c->regs[R1]|= INT_ALL_Rx;
+	write_zsreg(c, R1, c->regs[R1]);
+	c->regs[R14]&= ~DTRREQ;
+	write_zsreg(c, R14, c->regs[R14]);   
+	
+	if(c->rx_buf[0])
+	{
+		free_page((unsigned long)c->rx_buf[0]);
+		c->rx_buf[0]=NULL;
+	}
+	if(c->tx_dma_buf[0])
+	{
+		free_page((unsigned  long)c->tx_dma_buf[0]);
+		c->tx_dma_buf[0]=NULL;
+	}
+	chk=read_zsreg(c,R0);
+	write_zsreg(c, R3, c->regs[R3]);
+	z8530_rtsdtr(c,0);
+
+	spin_unlock_irqrestore(c->lock, flags);
+
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_sync_dma_close);
+
+/**
+ *	z8530_sync_txdma_open - Open a Z8530 for TX driven DMA
+ *	@dev: The network device to attach
+ *	@c: The Z8530 channel to configure in sync DMA mode.
+ *
+ *	Set up a Z85x30 device for synchronous DMA transmission. One
+ *	ISA DMA channel must be available for this to work. The receive
+ *	side is run in PIO mode, but then it has the bigger FIFO.
+ */
+
+int z8530_sync_txdma_open(struct net_device *dev, struct z8530_channel *c)
+{
+	unsigned long cflags, dflags;
+
+	printk("Opening sync interface for TX-DMA\n");
+	c->sync = 1;
+	c->mtu = dev->mtu+64;
+	c->count = 0;
+	c->skb = NULL;
+	c->skb2 = NULL;
+	
+	/*
+	 *	Allocate the DMA flip buffers. Limit by page size.
+	 *	Everyone runs 1500 mtu or less on wan links so this
+	 *	should be fine.
+	 */
+	 
+	if(c->mtu  > PAGE_SIZE/2)
+		return -EMSGSIZE;
+	 
+	c->tx_dma_buf[0]=(void *)get_zeroed_page(GFP_KERNEL|GFP_DMA);
+	if(c->tx_dma_buf[0]==NULL)
+		return -ENOBUFS;
+
+	c->tx_dma_buf[1] = c->tx_dma_buf[0] + PAGE_SIZE/2;
+
+
+	spin_lock_irqsave(c->lock, cflags);
+
+	/*
+	 *	Load the PIO receive ring
+	 */
+
+	z8530_rx_done(c);
+	z8530_rx_done(c);
+
+ 	/*
+	 *	Load the DMA interfaces up
+	 */
+
+	c->rxdma_on = 0;
+	c->txdma_on = 0;
+	
+	c->tx_dma_used=0;
+	c->dma_num=0;
+	c->dma_ready=1;
+	c->dma_tx = 1;
+
+ 	/*
+	 *	Enable DMA control mode
+	 */
+
+ 	/*
+	 *	TX DMA via DIR/REQ
+ 	 */
+	c->regs[R14]|= DTRREQ;
+	write_zsreg(c, R14, c->regs[R14]);     
+	
+	c->regs[R1]&= ~TxINT_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);
+	
+	/*
+	 *	Set up the DMA configuration
+	 */	
+	 
+	dflags = claim_dma_lock();
+
+	disable_dma(c->txdma);
+	clear_dma_ff(c->txdma);
+	set_dma_mode(c->txdma, DMA_MODE_WRITE);
+	disable_dma(c->txdma);
+
+	release_dma_lock(dflags);
+	
+	/*
+	 *	Select the DMA interrupt handlers
+	 */
+
+	c->rxdma_on = 0;
+	c->txdma_on = 1;
+	c->tx_dma_used = 1;
+	 
+	c->irqs = &z8530_txdma_sync;
+	z8530_rtsdtr(c,1);
+	write_zsreg(c, R3, c->regs[R3]|RxENABLE);
+	spin_unlock_irqrestore(c->lock, cflags);
+	
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_sync_txdma_open);
+
+/**
+ *	z8530_sync_txdma_close - Close down a TX driven DMA channel
+ *	@dev: Network device to detach
+ *	@c: Z8530 channel to move into discard mode
+ *
+ *	Shut down a DMA/PIO split mode synchronous interface. Halt the DMA, 
+ *	and  free the buffers.
+ */
+
+int z8530_sync_txdma_close(struct net_device *dev, struct z8530_channel *c)
+{
+	unsigned long dflags, cflags;
+	u8 chk;
+
+	
+	spin_lock_irqsave(c->lock, cflags);
+	
+	c->irqs = &z8530_nop;
+	c->max = 0;
+	c->sync = 0;
+	
+	/*
+	 *	Disable the PC DMA channels
+	 */
+	 
+	dflags = claim_dma_lock();
+
+	disable_dma(c->txdma);
+	clear_dma_ff(c->txdma);
+	c->txdma_on = 0;
+	c->tx_dma_used = 0;
+
+	release_dma_lock(dflags);
+
+	/*
+	 *	Disable DMA control mode
+	 */
+	 
+	c->regs[R1]&= ~WT_RDY_ENAB;
+	write_zsreg(c, R1, c->regs[R1]);            
+	c->regs[R1]&= ~(WT_RDY_RT|WT_FN_RDYFN|INT_ERR_Rx);
+	c->regs[R1]|= INT_ALL_Rx;
+	write_zsreg(c, R1, c->regs[R1]);
+	c->regs[R14]&= ~DTRREQ;
+	write_zsreg(c, R14, c->regs[R14]);   
+	
+	if(c->tx_dma_buf[0])
+	{
+		free_page((unsigned long)c->tx_dma_buf[0]);
+		c->tx_dma_buf[0]=NULL;
+	}
+	chk=read_zsreg(c,R0);
+	write_zsreg(c, R3, c->regs[R3]);
+	z8530_rtsdtr(c,0);
+
+	spin_unlock_irqrestore(c->lock, cflags);
+	return 0;
+}
+
+
+EXPORT_SYMBOL(z8530_sync_txdma_close);
+
+
+/*
+ *	Name strings for Z8530 chips. SGI claim to have a 130, Zilog deny
+ *	it exists...
+ */
+ 
+static const char *z8530_type_name[]={
+	"Z8530",
+	"Z85C30",
+	"Z85230"
+};
+
+/**
+ *	z8530_describe - Uniformly describe a Z8530 port
+ *	@dev: Z8530 device to describe
+ *	@mapping: string holding mapping type (eg "I/O" or "Mem")
+ *	@io: the port value in question
+ *
+ *	Describe a Z8530 in a standard format. We must pass the I/O as
+ *	the port offset isn't predictable. The main reason for this function
+ *	is to try and get a common format of report.
+ */
+
+void z8530_describe(struct z8530_dev *dev, char *mapping, unsigned long io)
+{
+	pr_info("%s: %s found at %s 0x%lX, IRQ %d\n",
+		dev->name, 
+		z8530_type_name[dev->type],
+		mapping,
+		Z8530_PORT_OF(io),
+		dev->irq);
+}
+
+EXPORT_SYMBOL(z8530_describe);
+
+/*
+ *	Locked operation part of the z8530 init code
+ */
+ 
+static inline int do_z8530_init(struct z8530_dev *dev)
+{
+	/* NOP the interrupt handlers first - we might get a
+	   floating IRQ transition when we reset the chip */
+	dev->chanA.irqs=&z8530_nop;
+	dev->chanB.irqs=&z8530_nop;
+	dev->chanA.dcdcheck=DCD;
+	dev->chanB.dcdcheck=DCD;
+
+	/* Reset the chip */
+	write_zsreg(&dev->chanA, R9, 0xC0);
+	udelay(200);
+	/* Now check its valid */
+	write_zsreg(&dev->chanA, R12, 0xAA);
+	if(read_zsreg(&dev->chanA, R12)!=0xAA)
+		return -ENODEV;
+	write_zsreg(&dev->chanA, R12, 0x55);
+	if(read_zsreg(&dev->chanA, R12)!=0x55)
+		return -ENODEV;
+		
+	dev->type=Z8530;
+	
+	/*
+	 *	See the application note.
+	 */
+	 
+	write_zsreg(&dev->chanA, R15, 0x01);
+	
+	/*
+	 *	If we can set the low bit of R15 then
+	 *	the chip is enhanced.
+	 */
+	 
+	if(read_zsreg(&dev->chanA, R15)==0x01)
+	{
+		/* This C30 versus 230 detect is from Klaus Kudielka's dmascc */
+		/* Put a char in the fifo */
+		write_zsreg(&dev->chanA, R8, 0);
+		if(read_zsreg(&dev->chanA, R0)&Tx_BUF_EMP)
+			dev->type = Z85230;	/* Has a FIFO */
+		else
+			dev->type = Z85C30;	/* Z85C30, 1 byte FIFO */
+	}
+		
+	/*
+	 *	The code assumes R7' and friends are
+	 *	off. Use write_zsext() for these and keep
+	 *	this bit clear.
+	 */
+	 
+	write_zsreg(&dev->chanA, R15, 0);
+		
+	/*
+	 *	At this point it looks like the chip is behaving
+	 */
+	 
+	memcpy(dev->chanA.regs, reg_init, 16);
+	memcpy(dev->chanB.regs, reg_init ,16);
+	
+	return 0;
+}
+
+/**
+ *	z8530_init - Initialise a Z8530 device
+ *	@dev: Z8530 device to initialise.
+ *
+ *	Configure up a Z8530/Z85C30 or Z85230 chip. We check the device
+ *	is present, identify the type and then program it to hopefully
+ *	keep quite and behave. This matters a lot, a Z8530 in the wrong
+ *	state will sometimes get into stupid modes generating 10Khz
+ *	interrupt streams and the like.
+ *
+ *	We set the interrupt handler up to discard any events, in case
+ *	we get them during reset or setp.
+ *
+ *	Return 0 for success, or a negative value indicating the problem
+ *	in errno form.
+ */
+
+int z8530_init(struct z8530_dev *dev)
+{
+	unsigned long flags;
+	int ret;
+
+	/* Set up the chip level lock */
+	spin_lock_init(&dev->lock);
+	dev->chanA.lock = &dev->lock;
+	dev->chanB.lock = &dev->lock;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	ret = do_z8530_init(dev);
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return ret;
+}
+
+
+EXPORT_SYMBOL(z8530_init);
+
+/**
+ *	z8530_shutdown - Shutdown a Z8530 device
+ *	@dev: The Z8530 chip to shutdown
+ *
+ *	We set the interrupt handlers to silence any interrupts. We then 
+ *	reset the chip and wait 100uS to be sure the reset completed. Just
+ *	in case the caller then tries to do stuff.
+ *
+ *	This is called without the lock held
+ */
+ 
+int z8530_shutdown(struct z8530_dev *dev)
+{
+	unsigned long flags;
+	/* Reset the chip */
+
+	spin_lock_irqsave(&dev->lock, flags);
+	dev->chanA.irqs=&z8530_nop;
+	dev->chanB.irqs=&z8530_nop;
+	write_zsreg(&dev->chanA, R9, 0xC0);
+	/* We must lock the udelay, the chip is offlimits here */
+	udelay(100);
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_shutdown);
+
+/**
+ *	z8530_channel_load - Load channel data
+ *	@c: Z8530 channel to configure
+ *	@rtable: table of register, value pairs
+ *	FIXME: ioctl to allow user uploaded tables
+ *
+ *	Load a Z8530 channel up from the system data. We use +16 to 
+ *	indicate the "prime" registers. The value 255 terminates the
+ *	table.
+ */
+
+int z8530_channel_load(struct z8530_channel *c, u8 *rtable)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(c->lock, flags);
+
+	while(*rtable!=255)
+	{
+		int reg=*rtable++;
+		if(reg>0x0F)
+			write_zsreg(c, R15, c->regs[15]|1);
+		write_zsreg(c, reg&0x0F, *rtable);
+		if(reg>0x0F)
+			write_zsreg(c, R15, c->regs[15]&~1);
+		c->regs[reg]=*rtable++;
+	}
+	c->rx_function=z8530_null_rx;
+	c->skb=NULL;
+	c->tx_skb=NULL;
+	c->tx_next_skb=NULL;
+	c->mtu=1500;
+	c->max=0;
+	c->count=0;
+	c->status=read_zsreg(c, R0);
+	c->sync=1;
+	write_zsreg(c, R3, c->regs[R3]|RxENABLE);
+
+	spin_unlock_irqrestore(c->lock, flags);
+	return 0;
+}
+
+EXPORT_SYMBOL(z8530_channel_load);
+
+
+/**
+ *	z8530_tx_begin - Begin packet transmission
+ *	@c: The Z8530 channel to kick
+ *
+ *	This is the speed sensitive side of transmission. If we are called
+ *	and no buffer is being transmitted we commence the next buffer. If
+ *	nothing is queued we idle the sync. 
+ *
+ *	Note: We are handling this code path in the interrupt path, keep it
+ *	fast or bad things will happen.
+ *
+ *	Called with the lock held.
+ */
+
+static void z8530_tx_begin(struct z8530_channel *c)
+{
+	unsigned long flags;
+	if(c->tx_skb)
+		return;
+		
+	c->tx_skb=c->tx_next_skb;
+	c->tx_next_skb=NULL;
+	c->tx_ptr=c->tx_next_ptr;
+	
+	if(c->tx_skb==NULL)
+	{
+		/* Idle on */
+		if(c->dma_tx)
+		{
+			flags=claim_dma_lock();
+			disable_dma(c->txdma);
+			/*
+			 *	Check if we crapped out.
+			 */
+			if (get_dma_residue(c->txdma))
+			{
+				c->netdevice->stats.tx_dropped++;
+				c->netdevice->stats.tx_fifo_errors++;
+			}
+			release_dma_lock(flags);
+		}
+		c->txcount=0;
+	}
+	else
+	{
+		c->txcount=c->tx_skb->len;
+		
+		
+		if(c->dma_tx)
+		{
+			/*
+			 *	FIXME. DMA is broken for the original 8530,
+			 *	on the older parts we need to set a flag and
+			 *	wait for a further TX interrupt to fire this
+			 *	stage off	
+			 */
+			 
+			flags=claim_dma_lock();
+			disable_dma(c->txdma);
+
+			/*
+			 *	These two are needed by the 8530/85C30
+			 *	and must be issued when idling.
+			 */
+			 
+			if(c->dev->type!=Z85230)
+			{
+				write_zsctrl(c, RES_Tx_CRC);
+				write_zsctrl(c, RES_EOM_L);
+			}	
+			write_zsreg(c, R10, c->regs[10]&~ABUNDER);
+			clear_dma_ff(c->txdma);
+			set_dma_addr(c->txdma, virt_to_bus(c->tx_ptr));
+			set_dma_count(c->txdma, c->txcount);
+			enable_dma(c->txdma);
+			release_dma_lock(flags);
+			write_zsctrl(c, RES_EOM_L);
+			write_zsreg(c, R5, c->regs[R5]|TxENAB);
+		}
+		else
+		{
+
+			/* ABUNDER off */
+			write_zsreg(c, R10, c->regs[10]);
+			write_zsctrl(c, RES_Tx_CRC);
+	
+			while(c->txcount && (read_zsreg(c,R0)&Tx_BUF_EMP))
+			{		
+				write_zsreg(c, R8, *c->tx_ptr++);
+				c->txcount--;
+			}
+
+		}
+	}
+	/*
+	 *	Since we emptied tx_skb we can ask for more
+	 */
+	netif_wake_queue(c->netdevice);
+}
+
+/**
+ *	z8530_tx_done - TX complete callback
+ *	@c: The channel that completed a transmit.
+ *
+ *	This is called when we complete a packet send. We wake the queue,
+ *	start the next packet going and then free the buffer of the existing
+ *	packet. This code is fairly timing sensitive.
+ *
+ *	Called with the register lock held.
+ */
+
+static void z8530_tx_done(struct z8530_channel *c)
+{
+	struct sk_buff *skb;
+
+	/* Actually this can happen.*/
+	if (c->tx_skb == NULL)
+		return;
+
+	skb = c->tx_skb;
+	c->tx_skb = NULL;
+	z8530_tx_begin(c);
+	c->netdevice->stats.tx_packets++;
+	c->netdevice->stats.tx_bytes += skb->len;
+	dev_kfree_skb_irq(skb);
+}
+
+/**
+ *	z8530_null_rx - Discard a packet
+ *	@c: The channel the packet arrived on
+ *	@skb: The buffer
+ *
+ *	We point the receive handler at this function when idle. Instead
+ *	of processing the frames we get to throw them away.
+ */
+ 
+void z8530_null_rx(struct z8530_channel *c, struct sk_buff *skb)
+{
+	dev_kfree_skb_any(skb);
+}
+
+EXPORT_SYMBOL(z8530_null_rx);
+
+/**
+ *	z8530_rx_done - Receive completion callback
+ *	@c: The channel that completed a receive
+ *
+ *	A new packet is complete. Our goal here is to get back into receive
+ *	mode as fast as possible. On the Z85230 we could change to using
+ *	ESCC mode, but on the older chips we have no choice. We flip to the
+ *	new buffer immediately in DMA mode so that the DMA of the next
+ *	frame can occur while we are copying the previous buffer to an sk_buff
+ *
+ *	Called with the lock held
+ */
+ 
+static void z8530_rx_done(struct z8530_channel *c)
+{
+	struct sk_buff *skb;
+	int ct;
+	
+	/*
+	 *	Is our receive engine in DMA mode
+	 */
+	 
+	if(c->rxdma_on)
+	{
+		/*
+		 *	Save the ready state and the buffer currently
+		 *	being used as the DMA target
+		 */
+		 
+		int ready=c->dma_ready;
+		unsigned char *rxb=c->rx_buf[c->dma_num];
+		unsigned long flags;
+		
+		/*
+		 *	Complete this DMA. Necessary to find the length
+		 */		
+		 
+		flags=claim_dma_lock();
+		
+		disable_dma(c->rxdma);
+		clear_dma_ff(c->rxdma);
+		c->rxdma_on=0;
+		ct=c->mtu-get_dma_residue(c->rxdma);
+		if(ct<0)
+			ct=2;	/* Shit happens.. */
+		c->dma_ready=0;
+		
+		/*
+		 *	Normal case: the other slot is free, start the next DMA
+		 *	into it immediately.
+		 */
+		 
+		if(ready)
+		{
+			c->dma_num^=1;
+			set_dma_mode(c->rxdma, DMA_MODE_READ|0x10);
+			set_dma_addr(c->rxdma, virt_to_bus(c->rx_buf[c->dma_num]));
+			set_dma_count(c->rxdma, c->mtu);
+			c->rxdma_on = 1;
+			enable_dma(c->rxdma);
+			/* Stop any frames that we missed the head of 
+			   from passing */
+			write_zsreg(c, R0, RES_Rx_CRC);
+		}
+		else
+			/* Can't occur as we dont reenable the DMA irq until
+			   after the flip is done */
+			netdev_warn(c->netdevice, "DMA flip overrun!\n");
+
+		release_dma_lock(flags);
+
+		/*
+		 *	Shove the old buffer into an sk_buff. We can't DMA
+		 *	directly into one on a PC - it might be above the 16Mb
+		 *	boundary. Optimisation - we could check to see if we
+		 *	can avoid the copy. Optimisation 2 - make the memcpy
+		 *	a copychecksum.
+		 */
+
+		skb = dev_alloc_skb(ct);
+		if (skb == NULL) {
+			c->netdevice->stats.rx_dropped++;
+			netdev_warn(c->netdevice, "Memory squeeze\n");
+		} else {
+			skb_put(skb, ct);
+			skb_copy_to_linear_data(skb, rxb, ct);
+			c->netdevice->stats.rx_packets++;
+			c->netdevice->stats.rx_bytes += ct;
+		}
+		c->dma_ready = 1;
+	} else {
+		RT_LOCK;
+		skb = c->skb;
+
+		/*
+		 *	The game we play for non DMA is similar. We want to
+		 *	get the controller set up for the next packet as fast
+		 *	as possible. We potentially only have one byte + the
+		 *	fifo length for this. Thus we want to flip to the new
+		 *	buffer and then mess around copying and allocating
+		 *	things. For the current case it doesn't matter but
+		 *	if you build a system where the sync irq isn't blocked
+		 *	by the kernel IRQ disable then you need only block the
+		 *	sync IRQ for the RT_LOCK area.
+		 *
+		 */
+		ct=c->count;
+
+		c->skb = c->skb2;
+		c->count = 0;
+		c->max = c->mtu;
+		if (c->skb) {
+			c->dptr = c->skb->data;
+			c->max = c->mtu;
+		} else {
+			c->count = 0;
+			c->max = 0;
+		}
+		RT_UNLOCK;
+
+		c->skb2 = dev_alloc_skb(c->mtu);
+		if (c->skb2 == NULL)
+			netdev_warn(c->netdevice, "memory squeeze\n");
+		else
+			skb_put(c->skb2, c->mtu);
+		c->netdevice->stats.rx_packets++;
+		c->netdevice->stats.rx_bytes += ct;
+	}
+	/*
+	 *	If we received a frame we must now process it.
+	 */
+	if (skb) {
+		skb_trim(skb, ct);
+		c->rx_function(c, skb);
+	} else {
+		c->netdevice->stats.rx_dropped++;
+		netdev_err(c->netdevice, "Lost a frame\n");
+	}
+}
+
+/**
+ *	spans_boundary - Check a packet can be ISA DMA'd
+ *	@skb: The buffer to check
+ *
+ *	Returns true if the buffer cross a DMA boundary on a PC. The poor
+ *	thing can only DMA within a 64K block not across the edges of it.
+ */
+
+static inline int spans_boundary(struct sk_buff *skb)
+{
+	unsigned long a=(unsigned long)skb->data;
+	a^=(a+skb->len);
+	if(a&0x00010000)	/* If the 64K bit is different.. */
+		return 1;
+	return 0;
+}
+
+/**
+ *	z8530_queue_xmit - Queue a packet
+ *	@c: The channel to use
+ *	@skb: The packet to kick down the channel
+ *
+ *	Queue a packet for transmission. Because we have rather
+ *	hard to hit interrupt latencies for the Z85230 per packet 
+ *	even in DMA mode we do the flip to DMA buffer if needed here
+ *	not in the IRQ.
+ *
+ *	Called from the network code. The lock is not held at this 
+ *	point.
+ */
+
+netdev_tx_t z8530_queue_xmit(struct z8530_channel *c, struct sk_buff *skb)
+{
+	unsigned long flags;
+	
+	netif_stop_queue(c->netdevice);
+	if(c->tx_next_skb)
+		return NETDEV_TX_BUSY;
+
+	
+	/* PC SPECIFIC - DMA limits */
+	
+	/*
+	 *	If we will DMA the transmit and its gone over the ISA bus
+	 *	limit, then copy to the flip buffer
+	 */
+	 
+	if(c->dma_tx && ((unsigned long)(virt_to_bus(skb->data+skb->len))>=16*1024*1024 || spans_boundary(skb)))
+	{
+		/* 
+		 *	Send the flip buffer, and flip the flippy bit.
+		 *	We don't care which is used when just so long as
+		 *	we never use the same buffer twice in a row. Since
+		 *	only one buffer can be going out at a time the other
+		 *	has to be safe.
+		 */
+		c->tx_next_ptr=c->tx_dma_buf[c->tx_dma_used];
+		c->tx_dma_used^=1;	/* Flip temp buffer */
+		skb_copy_from_linear_data(skb, c->tx_next_ptr, skb->len);
+	}
+	else
+		c->tx_next_ptr=skb->data;	
+	RT_LOCK;
+	c->tx_next_skb=skb;
+	RT_UNLOCK;
+	
+	spin_lock_irqsave(c->lock, flags);
+	z8530_tx_begin(c);
+	spin_unlock_irqrestore(c->lock, flags);
+	
+	return NETDEV_TX_OK;
+}
+
+EXPORT_SYMBOL(z8530_queue_xmit);
+
+/*
+ *	Module support
+ */
+static const char banner[] __initconst =
+	KERN_INFO "Generic Z85C30/Z85230 interface driver v0.02\n";
+
+static int __init z85230_init_driver(void)
+{
+	printk(banner);
+	return 0;
+}
+module_init(z85230_init_driver);
+
+static void __exit z85230_cleanup_driver(void)
+{
+}
+module_exit(z85230_cleanup_driver);
+
+MODULE_AUTHOR("Red Hat Inc.");
+MODULE_DESCRIPTION("Z85x30 synchronous driver core");
+MODULE_LICENSE("GPL");