plip.c

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/* $Id: plip.c,v 1.3.6.2 1997/04/16 15:07:56 phil Exp $ */
/* PLIP: A parallel port "network" driver for Linux. */
/* This driver is for parallel port with 5-bit cable (LapLink (R) cable). */
/*
 * Authors:	Donald Becker <[e-mail]>
 *		Tommy Thorn <[e-mail]>
 *		Tanabe Hiroyasu <[e-mail]>
 *		Alan Cox <[e-mail]>
 *		Peter Bauer <[e-mail]>
 *		Niibe Yutaka <[e-mail]>
 *		Nimrod Zimerman <[e-mail]>
 *
 * Enhancements:
 *		Modularization and ifreq/ifmap support by Alan Cox.
 *		Rewritten by Niibe Yutaka.
 *		parport-sharing awareness code by Philip Blundell.
 *		SMP locking by Niibe Yutaka.
 *		Support for parallel ports with no IRQ (poll mode),
 *		Modifications to use the parallel port API 
 *		by Nimrod Zimerman.
 *
 * Fixes:
 *		Niibe Yutaka
 *		  - Module initialization.
 *		  - MTU fix.
 *		  - Make sure other end is OK, before sending a packet.
 *		  - Fix immediate timer problem.
 *
 *		Al Viro
 *		  - Changed {enable,disable}_irq handling to make it work
 *		    with new ("stack") semantics.
 *
 *		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.
 */

/*
 * Original version and the name 'PLIP' from Donald Becker <[e-mail]>
 * inspired by Russ Nelson's parallel port packet driver.
 *
 * NOTE:
 *     Tanabe Hiroyasu had changed the protocol, and it was in Linux v1.0.
 *     Because of the necessity to communicate to DOS machines with the
 *     Crynwr packet driver, Peter Bauer changed the protocol again
 *     back to original protocol.
 *
 *     This version follows original PLIP protocol.
 *     So, this PLIP can't communicate the PLIP of Linux v1.0.
 */

/*
 *     To use with DOS box, please do (Turn on ARP switch):
 *	# ifconfig plip[0-2] arp
 */
static const char *version = "NET3 PLIP version 2.4-parport [e-mail]\n";

/*
  Sources:
	Ideas and protocols came from Russ Nelson's <[e-mail]>
	"parallel.asm" parallel port packet driver.

  The "Crynwr" parallel port standard specifies the following protocol:
    Trigger by sending nibble '0x8' (this causes interrupt on other end)
    count-low octet
    count-high octet
    ... data octets
    checksum octet
  Each octet is sent as <wait for rx. '0x1?'> <send 0x10+(octet&0x0F)>
			<wait for rx. '0x0?'> <send 0x00+((octet>>4)&0x0F)>

  The packet is encapsulated as if it were ethernet.

  The cable used is a de facto standard parallel null cable -- sold as
  a "LapLink" cable by various places.  You'll need a 12-conductor cable to
  make one yourself.  The wiring is:
    SLCTIN	17 - 17
    GROUND	25 - 25
    D0->ERROR	2 - 15		15 - 2
    D1->SLCT	3 - 13		13 - 3
    D2->PAPOUT	4 - 12		12 - 4
    D3->ACK	5 - 10		10 - 5
    D4->BUSY	6 - 11		11 - 6
  Do not connect the other pins.  They are
    D5,D6,D7 are 7,8,9
    STROBE is 1, FEED is 14, INIT is 16
    extra grounds are 18,19,20,21,22,23,24
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/if_ether.h>
#include <asm/system.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/lp.h>
#include <linux/init.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/inetdevice.h>
#include <linux/skbuff.h>
#include <linux/if_plip.h>
#include <net/neighbour.h>

#include <linux/tqueue.h>
#include <linux/ioport.h>
#include <linux/spinlock.h>
#include <asm/bitops.h>
#include <asm/irq.h>
#include <asm/byteorder.h>
#include <asm/semaphore.h>

#include <linux/parport.h>

/* Maximum number of devices to support. */
#define PLIP_MAX  8

/* Use 0 for production, 1 for verification, >2 for debug */
#ifndef NET_DEBUG
#define NET_DEBUG 1
#endif
static unsigned int net_debug = NET_DEBUG;

#define ENABLE(irq)  if (irq != -1) enable_irq(irq)
#define DISABLE(irq) if (irq != -1) disable_irq(irq)

/* In micro second */
#define PLIP_DELAY_UNIT		   1

/* Connection time out = PLIP_TRIGGER_WAIT * PLIP_DELAY_UNIT usec */
#define PLIP_TRIGGER_WAIT	 500

/* Nibble time out = PLIP_NIBBLE_WAIT * PLIP_DELAY_UNIT usec */
#define PLIP_NIBBLE_WAIT        3000

/* Bottom halves */
static void plip_kick_bh(struct net_device *dev);
static void plip_bh(struct net_device *dev);
static void plip_timer_bh(struct net_device *dev);

/* Interrupt handler */
static void plip_interrupt(int irq, void *dev_id, struct pt_regs *regs);

/* Functions for DEV methods */
static int plip_tx_packet(struct sk_buff *skb, struct net_device *dev);
static int plip_hard_header(struct sk_buff *skb, struct net_device *dev,
                            unsigned short type, void *daddr,
                            void *saddr, unsigned len);
static int plip_hard_header_cache(struct neighbour *neigh,
                                  struct hh_cache *hh);
static int plip_open(struct net_device *dev);
static int plip_close(struct net_device *dev);
static struct net_device_stats *plip_get_stats(struct net_device *dev);
static int plip_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);
static int plip_preempt(void *handle);
static void plip_wakeup(void *handle);

enum plip_connection_state {
	PLIP_CN_NONE=0,
	PLIP_CN_RECEIVE,
	PLIP_CN_SEND,
	PLIP_CN_CLOSING,
	PLIP_CN_ERROR
};

enum plip_packet_state {
	PLIP_PK_DONE=0,
	PLIP_PK_TRIGGER,
	PLIP_PK_LENGTH_LSB,
	PLIP_PK_LENGTH_MSB,
	PLIP_PK_DATA,
	PLIP_PK_CHECKSUM
};

enum plip_nibble_state {
	PLIP_NB_BEGIN,
	PLIP_NB_1,
	PLIP_NB_2,
};

struct plip_local {
	enum plip_packet_state state;
	enum plip_nibble_state nibble;
	union {
		struct {
#if defined(__LITTLE_ENDIAN)
			unsigned char lsb;
			unsigned char msb;
#elif defined(__BIG_ENDIAN)
			unsigned char msb;
			unsigned char lsb;
#else
#error	"Please fix the endianness defines in <asm/byteorder.h>"
#endif
		} b;
		unsigned short h;
	} length;
	unsigned short byte;
	unsigned char  checksum;
	unsigned char  data;
	struct sk_buff *skb;
};

struct net_local {
	struct net_device_stats enet_stats;
	struct tq_struct immediate;
	struct tq_struct deferred;
	struct tq_struct timer;
	struct plip_local snd_data;
	struct plip_local rcv_data;
	struct pardevice *pardev;
	unsigned long  trigger;
	unsigned long  nibble;
	enum plip_connection_state connection;
	unsigned short timeout_count;
	int is_deferred;
	int port_owner;
	int should_relinquish;
	int (*orig_hard_header)(struct sk_buff *skb, struct net_device *dev,
	                        unsigned short type, void *daddr,
	                        void *saddr, unsigned len);
	int (*orig_hard_header_cache)(struct neighbour *neigh,
	                              struct hh_cache *hh);
	spinlock_t lock;
	atomic_t kill_timer;
	struct semaphore killed_timer_sem;
};

inline static void enable_parport_interrupts (struct net_device *dev)
{
	if (dev->irq != -1)
	{
		struct parport *port =
		   ((struct net_local *)dev->priv)->pardev->port;
		port->ops->enable_irq (port);
	}
}

inline static void disable_parport_interrupts (struct net_device *dev)
{
	if (dev->irq != -1)
	{
		struct parport *port =
		   ((struct net_local *)dev->priv)->pardev->port;
		port->ops->disable_irq (port);
	}
}

inline static void write_data (struct net_device *dev, unsigned char data)
{
	struct parport *port =
	   ((struct net_local *)dev->priv)->pardev->port;

	port->ops->write_data (port, data);
}

inline static unsigned char read_status (struct net_device *dev)
{
	struct parport *port =
	   ((struct net_local *)dev->priv)->pardev->port;

	return port->ops->read_status (port);
}

/* Entry point of PLIP driver.
   Probe the hardware, and register/initialize the driver.

   PLIP is rather weird, because of the way it interacts with the parport
   system.  It is _not_ initialised from Space.c.  Instead, plip_init()
   is called, and that function makes up a "struct net_device" for each port, and
   then calls us here.

   */
int __init
plip_init_dev(struct net_device *dev, struct parport *pb)
{
	struct net_local *nl;
	struct pardevice *pardev;

	SET_MODULE_OWNER(dev);
	dev->irq = pb->irq;
	dev->base_addr = pb->base;

	if (pb->irq == -1) {
		printk(KERN_INFO "plip: %s has no IRQ. Using IRQ-less mode,"
		                 "which is fairly inefficient!\n", pb->name);
	}

	pardev = parport_register_device(pb, dev->name, plip_preempt,
					 plip_wakeup, plip_interrupt, 
					 0, dev);

	if (!pardev)
		return -ENODEV;

	printk(KERN_INFO "%s", version);
	if (dev->irq != -1)
		printk(KERN_INFO "%s: Parallel port at %#3lx, using IRQ %d.\n",
		       dev->name, dev->base_addr, dev->irq);
	else
		printk(KERN_INFO "%s: Parallel port at %#3lx, not using IRQ.\n",
		       dev->name, dev->base_addr);

	/* Fill in the generic fields of the device structure. */
	ether_setup(dev);

	/* Then, override parts of it */
	dev->hard_start_xmit	 = plip_tx_packet;
	dev->open		 = plip_open;
	dev->stop		 = plip_close;
	dev->get_stats 		 = plip_get_stats;
	dev->do_ioctl		 = plip_ioctl;
	dev->header_cache_update = NULL;
	dev->tx_queue_len 	 = 10;
	dev->flags	         = IFF_POINTOPOINT|IFF_NOARP;
	memset(dev->dev_addr, 0xfc, ETH_ALEN);

	/* Set the private structure */
	dev->priv = kmalloc(sizeof (struct net_local), GFP_KERNEL);
	if (dev->priv == NULL) {
		printk(KERN_ERR "%s: out of memory\n", dev->name);
		parport_unregister_device(pardev);
		return -ENOMEM;
	}
	memset(dev->priv, 0, sizeof(struct net_local));
	nl = (struct net_local *) dev->priv;

	nl->orig_hard_header    = dev->hard_header;
	dev->hard_header        = plip_hard_header;

	nl->orig_hard_header_cache = dev->hard_header_cache;
	dev->hard_header_cache     = plip_hard_header_cache;

	nl->pardev = pardev; 

	nl->port_owner = 0;

	/* Initialize constants */
	nl->trigger	= PLIP_TRIGGER_WAIT;
	nl->nibble	= PLIP_NIBBLE_WAIT;

	/* Initialize task queue structures */
	INIT_LIST_HEAD(&nl->immediate.list);
	nl->immediate.sync = 0;
	nl->immediate.routine = (void (*)(void *))plip_bh;
	nl->immediate.data = dev;

	INIT_LIST_HEAD(&nl->deferred.list);
	nl->deferred.sync = 0;
	nl->deferred.routine = (void (*)(void *))plip_kick_bh;
	nl->deferred.data = dev;

	if (dev->irq == -1) {
		INIT_LIST_HEAD(&nl->timer.list);
		nl->timer.sync = 0;
		nl->timer.routine = (void (*)(void *))plip_timer_bh;
		nl->timer.data = dev;
	}

	spin_lock_init(&nl->lock);

	return 0;
}

/* Bottom half handler for the delayed request.
   This routine is kicked by do_timer().
   Request `plip_bh' to be invoked. */
static void
plip_kick_bh(struct net_device *dev)
{
	struct net_local *nl = (struct net_local *)dev->priv;

	if (nl->is_deferred) {
		queue_task(&nl->immediate, &tq_immediate);
		mark_bh(IMMEDIATE_BH);
	}
}

/* Forward declarations of internal routines */
static int plip_none(struct net_device *, struct net_local *,
		     struct plip_local *, struct plip_local *);
static int plip_receive_packet(struct net_device *, struct net_local *,
			       struct plip_local *, struct plip_local *);
static int plip_send_packet(struct net_device *, struct net_local *,
			    struct plip_local *, struct plip_local *);
static int plip_connection_close(struct net_device *, struct net_local *,
				 struct plip_local *, struct plip_local *);
static int plip_error(struct net_device *, struct net_local *,
		      struct plip_local *, struct plip_local *);
static int plip_bh_timeout_error(struct net_device *dev, struct net_local *nl,
				 struct plip_local *snd,
				 struct plip_local *rcv,
				 int error);

#define OK        0
#define TIMEOUT   1
#define ERROR     2
#define HS_TIMEOUT	3

typedef int (*plip_func)(struct net_device *dev, struct net_local *nl,
			 struct plip_local *snd, struct plip_local *rcv);

static plip_func connection_state_table[] =
{
	plip_none,
	plip_receive_packet,
	plip_send_packet,
	plip_connection_close,
	plip_error
};

/* Bottom half handler of PLIP. */
static void
plip_bh(struct net_device *dev)
{
	struct net_local *nl = (struct net_local *)dev->priv;
	struct plip_local *snd = &nl->snd_data;
	struct plip_local *rcv = &nl->rcv_data;
	plip_func f;
	int r;

	nl->is_deferred = 0;
	f = connection_state_table[nl->connection];
	if ((r = (*f)(dev, nl, snd, rcv)) != OK
	    && (r = plip_bh_timeout_error(dev, nl, snd, rcv, r)) != OK) {
		nl->is_deferred = 1;
		queue_task(&nl->deferred, &tq_timer);
	}
}

static void
plip_timer_bh(struct net_device *dev)
{
	struct net_local *nl = (struct net_local *)dev->priv;
	
	if (!(atomic_read (&nl->kill_timer))) {
		plip_interrupt (-1, dev, NULL);

		queue_task (&nl->timer, &tq_timer);
	}
	else {
		up (&nl->killed_timer_sem);
	}
}

static int
plip_bh_timeout_error(struct net_device *dev, struct net_local *nl,
		      struct plip_local *snd, struct plip_local *rcv,
		      int error)
{
	unsigned char c0;
	/*
	 * This is tricky. If we got here from the beginning of send (either
	 * with ERROR or HS_TIMEOUT) we have IRQ enabled. Otherwise it's
	 * already disabled. With the old variant of {enable,disable}_irq()
	 * extra disable_irq() was a no-op. Now it became mortal - it's
	 * unbalanced and thus we'll never re-enable IRQ (until rmmod plip,
	 * that is). So we have to treat HS_TIMEOUT and ERROR from send
	 * in a special way.
	 */

	spin_lock_irq(&nl->lock);
	if (nl->connection == PLIP_CN_SEND) {

		if (error != ERROR) { /* Timeout */
			nl->timeout_count++;
			if ((error == HS_TIMEOUT
			     && nl->timeout_count <= 10)
			    || nl->timeout_count <= 3) {
				spin_unlock_irq(&nl->lock);
				/* Try again later */