patch-2.1.17 linux/drivers/net/atari_pamsnet.c

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diff -u --recursive --new-file v2.1.16/linux/drivers/net/atari_pamsnet.c linux/drivers/net/atari_pamsnet.c
@@ -0,0 +1,921 @@
+/* atari_pamsnet.c     PAMsNet device driver for linux68k.
+ *
+ * Version:	@(#)PAMsNet.c	0.2ß	03/31/96
+ *
+ * Author:  Torsten Lang <Torsten.Lang@ap.physik.uni-giessen.de> 
+ *                       <Torsten.Lang@jung.de>
+ *
+ * This driver is based on my driver PAMSDMA.c for MiNT-Net and
+ * on the driver bionet.c written by
+ *          Hartmut Laue <laue@ifk-mp.uni-kiel.de> 
+ * and      Torsten Narjes <narjes@ifk-mp.uni-kiel.de>
+ *
+ * Little adaptions for integration into pl7 by Roman Hodek
+ *
+	What is it ?
+	------------
+	This driver controls the PAMsNet LAN-Adapter which connects
+	an ATARI ST/TT via the ACSI-port to an Ethernet-based network.
+
+	This version can be compiled as a loadable module (See the
+	compile command at the bottom of this file).
+	At load time, you can optionally set the debugging level and the
+	fastest response time on the command line of 'insmod'.
+
+	'pamsnet_debug'
+		controls the amount of diagnostic messages:
+	  0  : no messages
+	  >0 : see code for meaning of printed messages
+
+	'pamsnet_min_poll_time' (always >=1)
+		gives the time (in jiffies) between polls. Low values
+		increase the system load (beware!)
+
+	When loaded, a net device with the name 'eth?' becomes available,
+	which can be controlled with the usual 'ifconfig' command.
+
+	It is possible to compile this driver into the kernel like other
+	(net) drivers. For this purpose, some source files (e.g. config-files
+	makefiles, Space.c) must be changed accordingly. (You may refer to
+	other drivers how to do it.) In this case, the device will be detected
+	at boot time and (probably) appear as 'eth0'.
+
+	Theory of Operation
+	-------------------
+	Because the ATARI DMA port is usually shared between several
+	devices (eg. harddisk, floppy) we cannot block the ACSI bus
+	while waiting for interrupts. Therefore we use a polling mechanism
+	to fetch packets from the adapter. For the same reason, we send
+	packets without checking that the previous packet has been sent to
+	the LAN. We rely on the higher levels of the networking code to detect
+	missing packets and resend them.
+
+	Before we access the ATARI DMA controller, we check if another
+	process is using the DMA. If not, we lock the DMA, perform one or
+	more packet transfers and unlock the DMA before returning.
+	We do not use 'stdma_lock' unconditionally because it is unclear
+	if the networking code can be set to sleep, which will happen if
+	another (possibly slow) device is using the DMA controller.
+
+	The polling is done via timer interrupts which periodically
+	'simulate' an interrupt from the Ethernet adapter. The time (in jiffies)
+	between polls varies depending on an estimate of the net activity.
+	The allowed range is given by the variable 'bionet_min_poll_time'
+	for the lower (fastest) limit and the constant 'MAX_POLL_TIME'
+	for the higher (slowest) limit.
+
+	Whenever a packet arrives, we switch to fastest response by setting
+	the polling time to its lowest limit. If the following poll fails,
+	because no packets have arrived, we increase the time for the next
+	poll. When the net activity is low, the polling time effectively
+	stays at its maximum value, resulting in the lowest load for the
+	machine.
+ */
+
+#define MAX_POLL_TIME	10
+
+static char *version =
+	"pamsnet.c:v0.2beta 30-mar-96 (c) Torsten Lang.\n";
+
+#ifdef MODULE
+#include <linux/module.h>
+#else
+#define MOD_INC_USE_COUNT
+#define MOD_DEC_USE_COUNT
+#endif
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/interrupt.h>
+#include <linux/ptrace.h>
+#include <linux/ioport.h>
+#include <linux/in.h>
+#include <linux/malloc.h>
+#include <linux/string.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/bitops.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+#include <linux/errno.h>
+#include <asm/atarihw.h>
+#include <asm/atariints.h>
+#include <asm/atari_stdma.h>
+#include <asm/atari_acsi.h>
+
+#include <linux/delay.h>
+#include <linux/timer.h>
+
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+
+#undef READ
+#undef WRITE
+  
+extern struct device *init_etherdev(struct device *dev, int sizeof_private);
+
+/* use 0 for production, 1 for verification, >2 for debug
+ */
+#ifndef NET_DEBUG
+#define NET_DEBUG 0
+#endif
+/*
+ * Global variable 'pamsnet_debug'. Can be set at load time by 'insmod'
+ */
+unsigned int pamsnet_debug = NET_DEBUG;
+static unsigned int pamsnet_min_poll_time = 2;
+
+
+/* Information that need to be kept for each board.
+ */
+struct net_local {
+	struct enet_statistics stats;
+	long open_time;			/* for debugging */
+	int  poll_time;			/* polling time varies with net load */
+};
+
+static struct nic_pkt_s {		/* packet format */
+	unsigned char	buffer[2048];
+} *nic_packet = 0;
+unsigned char *phys_nic_packet;
+
+typedef unsigned char HADDR[6]; /* 6-byte hardware address of lance */
+
+/* Index to functions, as function prototypes.
+ */
+static void	start (int target);
+static int	stop (int target);
+static int	testpkt (int target);
+static int	sendpkt (int target, unsigned char *buffer, int length);
+static int	receivepkt (int target, unsigned char *buffer);
+static int	inquiry (int target, unsigned char *buffer);
+static HADDR	*read_hw_addr(int target, unsigned char *buffer);
+static void	setup_dma (void *address, unsigned rw_flag, int num_blocks);
+static int	send_first (int target, unsigned char byte);
+static int	send_1_5 (int lun, unsigned char *command, int dma);
+static int	get_status (void);
+static int	calc_received (void *start_address);
+
+extern int pamsnet_probe(struct device *dev);
+
+static int pamsnet_open(struct device *dev);
+static int pamsnet_send_packet(struct sk_buff *skb, struct device *dev);
+static void pamsnet_poll_rx(struct device *);
+static int pamsnet_close(struct device *dev);
+static struct enet_statistics *net_get_stats(struct device *dev);
+static void pamsnet_tick(unsigned long);
+
+static void pamsnet_intr(int irq, void *data, struct pt_regs *fp);
+
+static struct timer_list pamsnet_timer = { NULL, NULL, 0, 0, pamsnet_tick };
+
+#define STRAM_ADDR(a)	(((a) & 0xff000000) == 0)
+
+typedef struct
+{
+	unsigned char reserved1[0x38];
+	HADDR  hwaddr;
+	unsigned char reserved2[0x1c2];
+} DMAHWADDR;
+
+/*
+ * Definitions of commands understood by the PAMs DMA adaptor.
+ *
+ * In general the DMA adaptor uses LUN 0, 5, 6 and 7 on one ID changeable
+ * by the PAM's Net software.
+ *
+ * LUN 0 works as a harddisk. You can boot the PAM's Net driver there.
+ * LUN 5 works as a harddisk and lets you access the RAM and some I/O HW
+ *       area. In sector 0, bytes 0x38-0x3d you find the ethernet HW address
+ *       of the adaptor.
+ * LUN 6 works as a harddisk and lets you access the firmware ROM.
+ * LUN 7 lets you send and receive packets.
+ *
+ * Some commands like the INQUIRY command work identical on all used LUNs.
+ * 
+ * UNKNOWN1 seems to read some data.
+ *          Command length is 6 bytes.
+ * UNKNOWN2 seems to read some data (command byte 1 must be !=0). The
+ *          following bytes seem to be something like an allocation length.
+ *          Command length is 6 bytes.
+ * READPKT  reads a packet received by the DMA adaptor.
+ *          Command length is 6 bytes.
+ * WRITEPKT sends a packet transferred by the following DMA phase. The length
+ *          of the packet is transferred in command bytes 3 and 4.
+ *          The adaptor automatically replaces the src hw address in an ethernet
+ *          packet by its own hw address.
+ *          Command length is 6 bytes.
+ * INQUIRY  has the same function as the INQUIRY command supported by harddisks
+ *          and other SCSI devices. It lets you detect which device you found
+ *          at a given address.
+ *          Command length is 6 bytes.
+ * START    initializes the DMA adaptor. After this command it is able to send
+ *          and receive packets. There is no status byte returned!
+ *          Command length is 1 byte.
+ * NUMPKTS  gives back the number of received packets waiting in the queue in
+ *          the status byte.
+ *          Command length is 1 byte.
+ * UNKNOWN3
+ * UNKNOWN4 Function of these three commands is unknown.
+ * UNKNOWN5 The command length of these three commands is 1 byte.
+ * DESELECT immediately deselects the DMA adaptor. May important with interrupt
+ *          driven operation.
+ *          Command length is 1 byte.
+ * STOP     resets the DMA adaptor. After this command packets can no longer
+ *          be received or transferred.
+ *          Command length is 6 byte.
+ */
+
+enum {UNKNOWN1=3, READPKT=8, UNKNOWN2, WRITEPKT=10, INQUIRY=18, START, 
+      NUMPKTS=22, UNKNOWN3, UNKNOWN4, UNKNOWN5, DESELECT, STOP};
+
+#define READSECTOR  READPKT
+#define WRITESECTOR WRITEPKT
+
+u_char *inquire8="MV      PAM's NET/GK";
+
+#define DMALOW   dma_wd.dma_lo
+#define DMAMID   dma_wd.dma_md
+#define DMAHIGH  dma_wd.dma_hi
+#define DACCESS  dma_wd.fdc_acces_seccount
+
+#define MFP_GPIP mfp.par_dt_reg
+
+/* Some useful functions */
+
+#define INT      (!(MFP_GPIP & 0x20))
+#define DELAY ({MFP_GPIP; MFP_GPIP; MFP_GPIP;})
+#define WRITEMODE(value)					\
+	({	u_short dummy = value;				\
+		__asm__ volatile("movew %0, 0xFFFF8606" : : "d"(dummy));	\
+		DELAY;						\
+	})
+#define WRITEBOTH(value1, value2)				\
+	({	u_long dummy = (u_long)(value1)<<16 | (u_short)(value2);	\
+		__asm__ volatile("movel %0, 0xFFFF8604" : : "d"(dummy));	\
+		DELAY;						\
+	})
+
+/* Definitions for DMODE */
+
+#define READ        0x000
+#define WRITE       0x100
+
+#define DMA_FDC     0x080
+#define DMA_ACSI    0x000
+
+#define DMA_DISABLE 0x040
+
+#define SEC_COUNT   0x010
+#define DMA_WINDOW  0x000
+
+#define REG_ACSI    0x008
+#define REG_FDC     0x000
+
+#define A1          0x002
+
+/* Timeout constants */
+
+#define TIMEOUTCMD HZ/2   /* ca. 500ms */
+#define TIMEOUTDMA HZ     /* ca. 1s */
+#define COMMAND_DELAY 500 /* ca. 0.5ms */
+
+unsigned rw;
+int lance_target = -1;
+int if_up = 0;
+
+/* The following routines access the ethernet board connected to the
+ * ACSI port via the st_dma chip.
+ */
+
+/* The following lowlevel routines work on physical addresses only and assume
+ * that eventually needed buffers are 
+ * - completely located in ST RAM
+ * - are contigous in the physical address space
+ */
+
+/* Setup the DMA counter */
+
+static void 
+setup_dma (address, rw_flag, num_blocks)
+	void *address;
+	unsigned rw_flag;
+	int num_blocks;
+{
+	WRITEMODE((unsigned) rw_flag          | DMA_FDC | SEC_COUNT | REG_ACSI |
+		  A1);
+	WRITEMODE((unsigned)(rw_flag ^ WRITE) | DMA_FDC | SEC_COUNT | REG_ACSI |
+		  A1);
+	WRITEMODE((unsigned) rw_flag          | DMA_FDC | SEC_COUNT | REG_ACSI |
+		  A1);
+	DMALOW  = (unsigned char)((unsigned long)address & 0xFF);
+	DMAMID  = (unsigned char)(((unsigned long)address >>  8) & 0xFF);
+	DMAHIGH = (unsigned char)(((unsigned long)address >> 16) & 0xFF);
+	WRITEBOTH((unsigned)num_blocks & 0xFF,
+		  rw_flag | DMA_FDC | DMA_WINDOW | REG_ACSI | A1);
+	rw = rw_flag;
+}
+
+/* Send the first byte of an command block */
+
+static int 
+send_first (target, byte)
+	int target;
+	unsigned char byte;
+{
+	rw = READ;
+	acsi_delay_end(COMMAND_DELAY);
+	/*
+	 * wake up ACSI
+	 */
+	WRITEMODE(DMA_FDC | DMA_WINDOW | REG_ACSI);
+	/*
+	 * write command byte
+	 */
+	WRITEBOTH((target << 5) | (byte & 0x1F), DMA_FDC |
+	          DMA_WINDOW | REG_ACSI | A1);
+	return (!acsi_wait_for_IRQ(TIMEOUTCMD));
+}
+
+/* Send the rest of an command block */
+
+static int 
+send_1_5 (lun, command, dma)
+	int lun;
+	unsigned char *command;
+	int dma;
+{
+	int i, j;
+	
+	for (i=0; i<5; i++) {
+		WRITEBOTH((!i ? (((lun & 0x7) << 5) | (command[i] & 0x1F))
+			      : command[i]),
+			  rw | REG_ACSI | DMA_WINDOW |
+			   ((i < 4) ? DMA_FDC
+				    : (dma ? DMA_ACSI
+					   : DMA_FDC)) | A1);
+		if (i < 4 && (j = !acsi_wait_for_IRQ(TIMEOUTCMD)))
+			return (j);
+	}
+	return (0);
+}
+
+/* Read a status byte */
+
+static int 
+get_status (void)
+{
+	WRITEMODE(DMA_FDC | DMA_WINDOW | REG_ACSI | A1);
+	acsi_delay_start();
+	return ((int)(DACCESS & 0xFF));
+}
+
+/* Calculate the number of received bytes */
+
+static int 
+calc_received (start_address)
+	void *start_address;
+{
+	return (int)(
+		(((unsigned long)DMAHIGH << 16) | ((unsigned)DMAMID << 8) | DMALOW)
+	      - (unsigned long)start_address);
+}
+
+/* The following midlevel routines still work on physical addresses ... */
+
+/* start() starts the PAM's DMA adaptor */
+
+static void
+start (target)
+	int target;
+{
+	send_first(target, START);
+}
+
+/* stop() stops the PAM's DMA adaptor and returns a value of zero in case of success */
+
+static int
+stop (target)
+	int target;
+{
+	int ret = -1;
+	unsigned char cmd_buffer[5];
+
+	if (send_first(target, STOP))
+		goto bad;
+	cmd_buffer[0] = cmd_buffer[1] = cmd_buffer[2] =
+	cmd_buffer[3] = cmd_buffer[4] = 0;
+	if (send_1_5(7, cmd_buffer, 0) ||
+	    !acsi_wait_for_IRQ(TIMEOUTDMA) ||
+	    get_status())
+		goto bad;
+	ret = 0;
+bad:
+	return (ret);
+}
+
+/* testpkt() returns the number of received packets waiting in the queue */
+
+static int
+testpkt(target)
+	int target;
+{
+	int ret = -1;
+
+	if (send_first(target, NUMPKTS))
+		goto bad;
+	ret = get_status();
+bad:
+	return (ret);
+}
+
+/* inquiry() returns 0 when PAM's DMA found, -1 when timeout, -2 otherwise */
+/* Please note: The buffer is for internal use only but must be defined!   */
+
+static int 
+inquiry (target, buffer)
+	int target;
+	unsigned char *buffer;
+{
+	int ret = -1;
+	unsigned char *vbuffer = (unsigned char *)PTOV(buffer);
+	unsigned char cmd_buffer[5];
+	
+	if (send_first(target, INQUIRY))
+		goto bad;
+	setup_dma(buffer, READ, 1);
+	vbuffer[8] = vbuffer[27] = 0; /* Avoid confusion with previous read data */
+	cmd_buffer[0] = cmd_buffer[1] = cmd_buffer[2] = cmd_buffer[4] = 0;
+	cmd_buffer[3] = 48;
+	if (send_1_5(5, cmd_buffer, 1) ||
+	    !acsi_wait_for_IRQ(TIMEOUTDMA) ||
+	    get_status() ||
+	    (calc_received(buffer) < 32))
+		goto bad;
+	dma_cache_maintenance((unsigned long)(buffer+8), 20, 0);
+	if (memcmp(inquire8, vbuffer+8, 20))
+		goto bad;
+	ret = 0;
+bad:
+	if (!!NET_DEBUG) {
+		vbuffer[8+20]=0;
+		printk("inquiry of target %d: %s\n", target, vbuffer+8);
+	}
+	return (ret);
+}
+
+/* 
+ * read_hw_addr() reads the sector containing the hwaddr and returns
+ * a pointer to it (virtual address!) or 0 in case of an error
+ */
+
+static HADDR 
+*read_hw_addr(target, buffer)
+	int target;
+	unsigned char *buffer;
+{
+	HADDR *ret = 0;
+	unsigned char cmd_buffer[5];
+
+	if (send_first(target, READSECTOR))
+		goto bad;
+	setup_dma(buffer, READ, 1);
+	cmd_buffer[0] = cmd_buffer[1] = cmd_buffer[2] = cmd_buffer[4] = 0;
+	cmd_buffer[3] = 1;
+	if (send_1_5(5, cmd_buffer, 1) ||
+	    !acsi_wait_for_IRQ(TIMEOUTDMA) ||
+	    get_status())
+		goto bad;
+	ret = (HADDR *)PTOV(&(((DMAHWADDR *)buffer)->hwaddr));
+	dma_cache_maintenance((unsigned long)buffer, 512, 0);
+bad:
+	return (ret);
+}
+
+static void
+pamsnet_intr(irq, data, fp)
+	int irq;
+	void *data;
+	struct pt_regs *fp;
+{
+	return;
+}
+
+/* receivepkt() loads a packet to a given buffer and returns its length */
+
+static int
+receivepkt (target, buffer)
+	int target;
+	unsigned char *buffer;
+{
+	int ret = -1;
+	unsigned char cmd_buffer[5];
+
+	if (send_first(target, READPKT))
+		goto bad;
+	setup_dma(buffer, READ, 3);
+	cmd_buffer[0] = cmd_buffer[1] = cmd_buffer[2] = cmd_buffer[4] = 0;
+	cmd_buffer[3] = 3;
+	if (send_1_5(7, cmd_buffer, 1) ||
+	    !acsi_wait_for_IRQ(TIMEOUTDMA) ||
+	    get_status())
+		goto bad;
+	ret = calc_received(buffer);
+bad:
+	return (ret);
+}
+
+/* sendpkt() sends a packet and returns a value of zero when the packet was sent
+             successfully */
+
+static int
+sendpkt (target, buffer, length)
+	int target;
+	unsigned char *buffer;
+	int length;
+{
+	int ret = -1;
+	unsigned char cmd_buffer[5];
+
+	if (send_first(target, WRITEPKT))
+		goto bad;
+	setup_dma(buffer, WRITE, 3);
+	cmd_buffer[0] = cmd_buffer[1] = cmd_buffer[4] = 0;
+	cmd_buffer[2] = length >> 8;
+	cmd_buffer[3] = length & 0xFF;
+	if (send_1_5(7, cmd_buffer, 1) ||
+	    !acsi_wait_for_IRQ(TIMEOUTDMA) ||
+	    get_status())
+		goto bad;
+	ret = 0;
+bad:
+	return (ret);
+}
+
+/* The following higher level routines work on virtual addresses and convert them to
+ * physical addresses when passed to the lowlevel routines. It's up to the higher level
+ * routines to copy data from Alternate RAM to ST RAM if neccesary!
+ */
+
+/* Check for a network adaptor of this type, and return '0' if one exists.
+ */
+
+extern int
+pamsnet_probe (dev)
+	struct device *dev;
+{
+	int i;
+	HADDR *hwaddr;
+	
+	unsigned char station_addr[6];
+	static unsigned version_printed = 0;
+	/* avoid "Probing for..." printed 4 times - the driver is supporting only one adapter now! */
+	static int no_more_found = 0;
+
+	if (no_more_found)
+		return ENODEV;
+
+	no_more_found = 1;
+	
+	printk("Probing for PAM's Net/GK Adapter...\n");
+
+	/* Allocate the DMA buffer here since we need it for probing! */
+
+	nic_packet = (struct nic_pkt_s *)acsi_buffer;
+	phys_nic_packet = (unsigned char *)phys_acsi_buffer;
+	if (pamsnet_debug > 0) {
+		printk("nic_packet at 0x%p, phys at 0x%p\n",
+			   nic_packet, phys_nic_packet );
+	}
+
+	stdma_lock(pamsnet_intr, NULL);
+	DISABLE_IRQ();
+
+	for (i=0; i<8; i++) {
+		/* Do two inquiries to cover cases with strange equipment on previous ID */
+		/* blocking the ACSI bus (like the SLMC804 laser printer controller...   */
+		inquiry(i, phys_nic_packet);
+		if (!inquiry(i, phys_nic_packet)) {
+			lance_target = i;
+			break;
+		}
+	}
+
+	if (!!NET_DEBUG)
+		printk("ID: %d\n",i);
+
+	if (lance_target >= 0) {
+		if (!(hwaddr = read_hw_addr(lance_target, phys_nic_packet)))
+			lance_target = -1;
+		else
+			memcpy (station_addr, hwaddr, ETH_ALEN);
+	}
+	
+	ENABLE_IRQ();
+	stdma_release();
+
+	if (lance_target < 0)
+		printk("No PAM's Net/GK found.\n");
+
+	if ((dev == NULL) || (lance_target < 0))
+		return ENODEV;
+	if (pamsnet_debug > 0 && version_printed++ == 0)
+		printk(version);
+
+	printk("%s: %s found on target %01d, eth-addr: %02x:%02x:%02x:%02x:%02x:%02x.\n",
+		dev->name, "PAM's Net/GK", lance_target,
+		station_addr[0], station_addr[1], station_addr[2],
+		station_addr[3], station_addr[4], station_addr[5]);
+
+	/* Initialize the device structure. */
+	if (dev->priv == NULL)
+		dev->priv = kmalloc(sizeof(struct net_local), GFP_KERNEL);
+	memset(dev->priv, 0, sizeof(struct net_local));
+
+	dev->open		= pamsnet_open;
+	dev->stop		= pamsnet_close;
+	dev->hard_start_xmit	= pamsnet_send_packet;
+	dev->get_stats		= net_get_stats;
+
+	/* Fill in the fields of the device structure with ethernet-generic
+	 * values. This should be in a common file instead of per-driver.
+	 */
+
+	for (i = 0; i < ETH_ALEN; i++) {
+#if 0
+		dev->broadcast[i] = 0xff;
+#endif
+		dev->dev_addr[i]  = station_addr[i];
+	}
+	ether_setup(dev);
+
+	return(0);
+}
+
+/* Open/initialize the board.  This is called (in the current kernel)
+   sometime after booting when the 'ifconfig' program is run.
+
+   This routine should set everything up anew at each open, even
+   registers that "should" only need to be set once at boot, so that
+   there is non-reboot way to recover if something goes wrong.
+ */
+static int
+pamsnet_open(struct device *dev) {
+	struct net_local *lp = (struct net_local *)dev->priv;
+
+	if (pamsnet_debug > 0)
+		printk("pamsnet_open\n");
+	stdma_lock(pamsnet_intr, NULL);
+	DISABLE_IRQ();
+
+	/* Reset the hardware here.
+	 */
+	if (!if_up)
+		start(lance_target);
+	if_up = 1;
+	lp->open_time = 0;	/*jiffies*/
+	lp->poll_time = MAX_POLL_TIME;
+
+	dev->tbusy = 0;
+	dev->interrupt = 0;
+	dev->start = 1;
+
+	ENABLE_IRQ();
+	stdma_release();
+	pamsnet_timer.data = (long)dev;
+	pamsnet_timer.expires = jiffies + lp->poll_time;
+	add_timer(&pamsnet_timer);
+	MOD_INC_USE_COUNT;
+	return 0;
+}
+
+static int
+pamsnet_send_packet(struct sk_buff *skb, struct device *dev) {
+	struct net_local *lp = (struct net_local *)dev->priv;
+	unsigned long flags;
+
+	/* If some higher layer thinks we've missed an tx-done interrupt we
+	 * are passed NULL. Caution: dev_tint() handles the cli()/sti() itself.
+	 */
+	if (skb == NULL) {
+		dev_tint(dev);
+		return 0;
+	}
+	/* Block a timer-based transmit from overlapping.  This could better be
+	 * done with atomic_swap(1, dev->tbusy), but set_bit() works as well.
+	 */
+	save_flags(flags);
+	cli();
+
+	if (stdma_islocked()) {
+		restore_flags(flags);
+		lp->stats.tx_errors++;
+	}
+	else {
+		int length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;
+		unsigned long buf = VTOP(skb->data);
+		int stat;
+
+		stdma_lock(pamsnet_intr, NULL);
+		DISABLE_IRQ();
+
+		restore_flags(flags);
+		if( !STRAM_ADDR(buf+length-1) ) {
+			memcpy(nic_packet->buffer, skb->data, length);
+			buf = (unsigned long)phys_nic_packet;
+		}
+
+		dma_cache_maintenance(buf, length, 1);
+
+		stat = sendpkt(lance_target, (unsigned char *)buf, length);
+		ENABLE_IRQ();
+		stdma_release();
+
+		dev->trans_start = jiffies;
+		dev->tbusy	 = 0;
+	}
+	dev_kfree_skb(skb, FREE_WRITE);
+
+	/* You might need to clean up and record Tx statistics here.
+	 */
+	lp->stats.tx_packets++;
+	return 0;
+}
+
+/* We have a good packet(s), get it/them out of the buffers.
+ */
+static void
+pamsnet_poll_rx(struct device *dev) {
+	struct net_local *lp = (struct net_local *)dev->priv;
+	int boguscount;
+	int pkt_len;
+	struct sk_buff *skb;
+	unsigned long flags;
+
+	save_flags(flags);
+	cli();
+	/* ++roman: Take care at locking the ST-DMA... This must be done with ints
+	 * off, since otherwise an int could slip in between the question and the
+	 * locking itself, and then we'd go to sleep... And locking itself is
+	 * necessary to keep the floppy_change timer from working with ST-DMA
+	 * registers. */
+	if (stdma_islocked()) {
+		restore_flags(flags);
+		return;
+	}
+	stdma_lock(pamsnet_intr, NULL);
+	DISABLE_IRQ();
+	restore_flags(flags);
+
+	boguscount = testpkt(lance_target);
+	if( lp->poll_time < MAX_POLL_TIME ) lp->poll_time++;
+
+	while(boguscount--) {
+		pkt_len = receivepkt(lance_target, phys_nic_packet);
+	  
+		if( pkt_len < 60 ) break;
+
+		/* Good packet... */
+
+		dma_cache_maintenance((unsigned long)phys_nic_packet, pkt_len, 0);
+
+		lp->poll_time = pamsnet_min_poll_time;    /* fast poll */
+		if( pkt_len >= 60 && pkt_len <= 2048 ) {
+			if (pkt_len > 1514)
+				pkt_len = 1514;
+
+			/* Malloc up new buffer.
+			 */
+			skb = alloc_skb(pkt_len, GFP_ATOMIC);
+			if (skb == NULL) {
+				printk("%s: Memory squeeze, dropping packet.\n",
+					dev->name);
+				lp->stats.rx_dropped++;
+				break;
+			}
+			skb->len = pkt_len;
+			skb->dev = dev;
+
+			/* 'skb->data' points to the start of sk_buff data area.
+			 */
+			memcpy(skb->data, nic_packet->buffer, pkt_len);
+			netif_rx(skb);
+			lp->stats.rx_packets++;
+		}
+	}
+
+	/* If any worth-while packets have been received, dev_rint()
+	   has done a mark_bh(INET_BH) for us and will work on them
+	   when we get to the bottom-half routine.
+	 */
+
+	ENABLE_IRQ();
+	stdma_release();
+	return;
+}
+
+/* pamsnet_tick: called by pamsnet_timer. Reads packets from the adapter,
+ * passes them to the higher layers and restarts the timer.
+ */
+static void
+pamsnet_tick(unsigned long data) {
+	struct device	 *dev = (struct device *)data;
+	struct net_local *lp = (struct net_local *)dev->priv;
+
+	if( pamsnet_debug > 0 && (lp->open_time++ & 7) == 8 )
+		printk("pamsnet_tick: %ld\n", lp->open_time);
+
+	pamsnet_poll_rx(dev);
+
+	pamsnet_timer.expires = jiffies + lp->poll_time;
+	add_timer(&pamsnet_timer);
+}
+
+/* The inverse routine to pamsnet_open().
+ */
+static int
+pamsnet_close(struct device *dev) {
+	struct net_local *lp = (struct net_local *)dev->priv;
+
+	if (pamsnet_debug > 0)
+		printk("pamsnet_close, open_time=%ld\n", lp->open_time);
+	del_timer(&pamsnet_timer);
+	stdma_lock(pamsnet_intr, NULL);
+	DISABLE_IRQ();
+
+	if (if_up)
+		stop(lance_target);
+	if_up = 0;
+
+	lp->open_time = 0;
+
+	dev->tbusy = 1;
+	dev->start = 0;
+
+	ENABLE_IRQ();
+	stdma_release();
+	MOD_DEC_USE_COUNT;
+	return 0;
+}
+
+/* Get the current statistics.
+   This may be called with the card open or closed.
+ */
+static struct enet_statistics *
+net_get_stats(struct device *dev) {
+	struct net_local *lp = (struct net_local *)dev->priv;
+	return &lp->stats;
+}
+
+
+#ifdef MODULE
+
+#include <linux/version.h>
+
+/* We should include the kernel identification string in the module.
+ */
+static char kernel_version[] = UTS_RELEASE;
+
+#undef	NEXT_DEV
+#define NEXT_DEV	(&pam_dev)
+
+static struct device pam_dev =  
+	{
+		"        ",	/* filled in by register_netdev() */
+		0, 0, 0, 0,	/* memory */
+		0, 0,		/* base, irq */
+		0, 0, 0, NEXT_DEV, pamsnet_probe,
+	};
+
+int
+init_module(void) {
+	int err;
+	
+	if ((err = register_netdev(&pam_dev))) {
+		if (err == -EEXIST)  {
+			printk("PAM's Net/GK: devices already present. Module not loaded.\n");
+		}
+		return err;
+	}
+	return 0;
+}  
+
+void
+cleanup_module(void) {
+	unregister_netdev(&pam_dev);
+}
+                      
+#endif /* MODULE */
+
+/* Local variables:
+ *  compile-command: "gcc -D__KERNEL__ -I/usr/src/linux/include
+	-b m68k-linuxaout -Wall -Wstrict-prototypes -O2
+	-fomit-frame-pointer -pipe -DMODULE -I../../net/inet -c atari_pamsnet.c"
+ *  version-control: t
+ *  kept-new-versions: 5
+ *  tab-width: 8
+ * End:
+ */
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TCL-scripts by Sam Shen, slshen@lbl.gov