ne2000.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*  ne2k.c -- RTEMS NE2000 Ethernet driver.
 *  Written by Ian Lance Taylor, Zembu Labs.
 *  October, 1998.
 *
 *  The license and distribution terms for this file may be
 *  found in found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id: ne2000.c,v 1.9.6.1 2003/09/04 18:44:03 joel Exp $
 *
 *  Both the ne2000 and the wd80x3 are based on the National Semiconductor
 *  8390 chip, so there is a fair amount of overlap between the two
 *  drivers.  It would be possible in principle to combine some code into
 *  a separate set of subroutines called by both.  In fact, the drivers in
 *  both OpenBSD and Linux work this way.  I didn't bother, because for
 *  the relatively simple drivers used by RTEMS, the overlap is not
 *  especially large, and any reasonable use of subroutines would lead to
 *  slightly less efficient code.

 *  This ne2000 driver uses two transmit buffers.  While one packet is
 *  being transmitted over the Ethernet, RTEMS will upload another.  Since
 *  uploading a packet to the ne2000 is rather slow, I don't think there
 *  is any point to having more than two transmit buffers.  However, the
 *  code does make it possible, by changing NE_TX_BUFS, although that
 *  would of course reduce the number of receive buffers.
 *
 *  I suspect that the wd80x3 driver would benefit slightly from copying
 *  the multiple transmit buffer code.  However, I have no way to test
 *  that.
 */

#include <bsp.h>
#include <wd80x3.h>

#include <stdio.h>
#include <assert.h>

#include <rtems/error.h>
#include <rtems/rtems_bsdnet.h>

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <irq.h>

/* Define this to force byte-wide data transfers with the NIC. This
   is needed for boards like the TS-1325 386EX PC, which support only
   an 8-bit PC/104 bus.  Undefine this on a normal PC.*/

/* #define NE2000_BYTE_TRANSFERS */

/* Define this to print debugging messages with printk.  */

/* #define DEBUG_NE2000 */
/* #define DEBUG_NE */

/* We expect to be able to read a complete packet into an mbuf.  */

#if (MCLBYTES < 1520)
# error "Driver must have MCLBYTES >= 1520"
#endif

/* The 8390 macro definitions in wd80x3.h expect RO to be defined.  */
#define RO 0

/* Minimum size of Ethernet packet.  */
#define ET_MINLEN 60

/* The number of NE2000 devices supported by this driver.  */

#define NNEDRIVER 1

/* RTEMS event number used by the interrupt handler to signal the
   driver task.  This must not be any of the events used by the
   network task synchronization.  */
#define INTERRUPT_EVENT RTEMS_EVENT_1

/* RTEMS event number used to start the transmit daemon.  This must
   not be the same as INTERRUPT_EVENT.  */
#define START_TRANSMIT_EVENT RTEMS_EVENT_2

/* Interrupts we want to handle from the device.  */

#define NE_INTERRUPTS \
  (MSK_PRX | MSK_PTX | MSK_RXE | MSK_TXE | MSK_OVW | MSK_CNT)

/* The size of a page in device memory.  */

#define NE_PAGE_SIZE (256)

/* The first page address in device memory.  */

#define NE_START_PAGE (0x40)

/* The last page address, plus 1.  */

#define NE_STOP_PAGE (0x80)

/* The number of pages used for a single transmit buffer.  This is
   1536 bytes, enough for a full size packet.  */

#define NE_TX_PAGES (6)

/* The number of transmit buffers.  We use two, so we can load one
   packet while the other is being sent.  */

#define NE_TX_BUFS (2)

/* We use the first pages in memory as transmit buffers, and the
   remaining ones as receive buffers.  */

#define NE_FIRST_TX_PAGE (NE_START_PAGE)

#define NE_FIRST_RX_PAGE (NE_FIRST_TX_PAGE + NE_TX_PAGES * NE_TX_BUFS)

/* Data we store for each NE2000 device.  */

struct ne_softc {
  /* The bsdnet information structure.  */
  struct arpcom arpcom;

  /* The interrupt request number.  */
  unsigned int irno;
  /* The base IO port number.  */
  unsigned int port;

  /* Whether we accept broadcasts.  */
  int accept_broadcasts;

  /* The thread ID of the transmit task.   */
  rtems_id tx_daemon_tid;
  /* The thread ID of the receive task.  */
  rtems_id rx_daemon_tid;

  /* Whether we use byte-transfers with the device. */
  rtems_boolean byte_transfers;

  /* The number of memory buffers which the transmit daemon has loaded
     with data to be sent, but which have not yet been completely
     sent.  */
  int inuse;
  /* The index of the next available transmit memory buffer.  */
  int nextavail;
  /* The index of the next transmit buffer to send.  */
  int nextsend;
  /* Nonzero if the device is currently transmitting a packet.  */
  int transmitting;
  /* The length of the data stored in each transmit buffer.  */
  int sendlen[NE_TX_BUFS];

  /* Set if we have a packet overrun while receiving.  */
  int overrun;
  /* Set if we should resend after an overrun.  */
  int resend;

  /* Statistics.  */
  struct {
    /* Number of packets received.  */
    unsigned long rx_packets;
    /* Number of packets sent.  */
    unsigned long tx_packets;
    /* Number of interrupts.  */
    unsigned long interrupts;
    /* Number of receive acknowledgements.  */
    unsigned long rx_acks;
    /* Number of transmit acknowledgements.  */
    unsigned long tx_acks;
    /* Number of packet overruns.  */
    unsigned long overruns;
    /* Number of frame errors.  */
    unsigned long rx_frame_errors;
    /* Number of CRC errors.  */
    unsigned long rx_crc_errors;
    /* Number of missed packets.  */
    unsigned long rx_missed_errors;
  } stats;
};

/* The list of NE2000 devices on this system.  */

static struct ne_softc ne_softc[NNEDRIVER];

/*
 * receive ring descriptor
 *
 * The National Semiconductor DS8390 Network interface controller uses
 * the following receive ring headers.  The way this works is that the
 * memory on the interface card is chopped up into 256 bytes blocks.
 * A contiguous portion of those blocks are marked for receive packets
 * by setting start and end block #'s in the NIC.  For each packet that
 * is put into the receive ring, one of these headers (4 bytes each) is
 * tacked onto the front. The first byte is a copy of the receiver status
 * register at the time the packet was received.
 */
struct ne_ring
{
	unsigned char rsr;    /* receiver status */
	unsigned char next;   /* pointer to next packet	*/
	unsigned short count; /* bytes in packet (length + 4)	*/
};

/* Forward declarations to avoid warnings */

static void ne_init_irq_handler (int irno);
static void ne_stop (struct ne_softc *sc);
static void ne_stop_hardware (struct ne_softc *sc);
static void ne_init (void *arg);
static void ne_init_hardware (struct ne_softc *sc);

static void ne_reset(struct ne_softc *sc);
#ifdef DEBUG_NE
static void ne_dump(struct ne_softc *sc);
#endif

/* Find the NE2000 device which is attached at a particular interrupt
   vector.  */

static struct ne_softc *
ne_device_for_irno (int irno)
{
  int i;

  for (i = 0; i < NNEDRIVER; ++i)
    {
      if (ne_softc[i].irno == irno
          && ne_softc[i].arpcom.ac_if.if_softc != NULL)
        return &ne_softc[i];
    }

  return NULL;
}

/* Read data from an NE2000 device.  Read LEN bytes at ADDR, storing
   them into P.  */

static void
ne_read_data (struct ne_softc *sc, int addr, int len, unsigned char *p)
{
  unsigned int port = sc->port;
  unsigned int dport = port + DATAPORT;

  outport_byte (port + CMDR, MSK_PG0 | MSK_RD2 | MSK_STA);
  outport_byte (port + RBCR0, len);
  outport_byte (port + RBCR1, len >> 8);
  outport_byte (port + RSAR0, addr);
  outport_byte (port + RSAR1, addr >> 8);
  outport_byte (port + CMDR, MSK_PG0 | MSK_RRE | MSK_STA);

  if (sc->byte_transfers)
  {
    unsigned char d;
    while (len > 0)
    {
      inport_byte(dport, d);
      *p++ = d;
      len--;
    }
  }
  else  /* word transfers */
  {
    unsigned short d;
    while (len > 1)
    {
      inport_word(dport, d);
      *p++ = d;
      *p++ = d >> 8;
      len -= 2;
    }
    if (len)
    {
      inport_word(dport, d);
      *p++ = d;
    }
  }

  outport_byte (port + ISR, MSK_RDC);
}

/* Handle the current NE2000 status.  This is called when the device
   signals an interrupt.  It is also called at other times while
   NE2000 interrupts have been disabled.  */

static void
ne_check_status (struct ne_softc *sc, int from_irq_handler)
{
  struct ifnet *ifp = &sc->arpcom.ac_if;
  unsigned int port = sc->port;
  unsigned char status;

  /* It seems that we need to use a loop here, because if the NE2000
     signals an interrupt because packet transmission is complete, and
     then receives a packet while interrupts are disabled, it seems to
     sometimes fail to signal the interrupt for the received packet
     when interrupts are reenabled.  (Based on the behaviour of the
     Realtek 8019AS chip).  */

  /* int count = 0; */
  while (1)
  {
    inport_byte (port + ISR, status);
    if (status == 0)
      break;

    /* ack */
    outport_byte (port + ISR, status);

#ifdef DEBUG_NE2000
    printk ("NE2000 status 0x%x (8259 enabled: %s; mask: %x)\n", status,
            i8259s_cache & (1 << sc->irno) ? "no" : "yes",
            i8259s_cache);
#endif

    /* Check for incoming packet overwrite.  */
    if (status & MSK_OVW)
    {
      ifp->if_timer = 0;
#ifdef DEBUG_NE
      printk("^");
#endif
      ++sc->stats.overruns;
      ne_reset(sc);
      /* Reenable device interrupts.  */
      if (from_irq_handler)
        outport_byte(port + IMR, NE_INTERRUPTS);
      return;
    }

    /* Check for transmitted packet.  The transmit daemon may now be
       able to send another packet to the device.  */
    if ((status & (MSK_PTX | MSK_TXE)) != 0)
    {
      ifp->if_timer = 0;
      ++sc->stats.tx_acks;
      --sc->inuse;
      sc->transmitting = 0;
      if (sc->inuse > 0 || (sc->arpcom.ac_if.if_flags & IFF_OACTIVE) != 0)
        rtems_event_send (sc->tx_daemon_tid, START_TRANSMIT_EVENT);
    }

    /* Check for received packet.  */
    if ((status & (MSK_PRX | MSK_RXE)) != 0)
    {
      ++sc->stats.rx_acks;
      rtems_event_send (sc->rx_daemon_tid, INTERRUPT_EVENT);
    }

    /* Check for counter change.  */
    if ((status & MSK_CNT) != 0)
    {
      unsigned char add;
      inport_byte (port + CNTR0, add);
      sc->stats.rx_frame_errors += add;
      inport_byte (port + CNTR1, add);
      sc->stats.rx_crc_errors += add;
      inport_byte (port + CNTR2, add);
      sc->stats.rx_missed_errors += add;
    }

    break;
    /* if (++count >= 1000)
    {
      printk("status: %x\n", status);
      ne_reset(sc);
      if (from_irq_handler)
        outport_byte(port + IMR, NE_INTERRUPTS);
      return;
    } */
  }

  outport_byte (port + CMDR, MSK_PG0 | MSK_STA | MSK_RD2);
}

/* Handle an NE2000 interrupt.  */

static void
ne_interrupt_handler (rtems_vector_number v)
{
  struct ne_softc *sc;

  sc = ne_device_for_irno (v);
  if (sc == NULL)
    return;

  ++sc->stats.interrupts;

#ifdef DEBUG_NE
  printk("!");
#endif
  ne_check_status(sc, 1);
}

/* Turn NE2000 interrupts on.  */

static void
ne_interrupt_on (const rtems_irq_connect_data *irq)
{
  struct ne_softc *sc;

#ifdef DEBUG_NE
  printk ("ne_interrupt_on()\n");
#endif
  sc = ne_device_for_irno (irq->name);
  if (sc != NULL)
    outport_byte (sc->port + IMR, NE_INTERRUPTS);
}

/* Turn NE2000 interrupts off.  See ne_interrupt_on.  */

static void
ne_interrupt_off (const rtems_irq_connect_data *irq)
{
  struct ne_softc *sc;

#ifdef DEBUG_NE
  printk ("ne_interrupt_off()\n");
#endif