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xpnet.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1999,2001-2005 Silicon Graphics, Inc. All rights reserved.
 */


/*
 * Cross Partition Network Interface (XPNET) support
 *
 *    XPNET provides a virtual network layered on top of the Cross
 *    Partition communication layer.
 *
 *    XPNET provides direct point-to-point and broadcast-like support
 *    for an ethernet-like device.  The ethernet broadcast medium is
 *    replaced with a point-to-point message structure which passes
 *    pointers to a DMA-capable block that a remote partition should
 *    retrieve and pass to the upper level networking layer.
 *
 */


#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/delay.h>
#include <linux/ethtool.h>
#include <linux/mii.h>
#include <linux/smp.h>
#include <linux/string.h>
#include <asm/sn/bte.h>
#include <asm/sn/io.h>
#include <asm/sn/sn_sal.h>
#include <asm/types.h>
#include <asm/atomic.h>
#include <asm/sn/xp.h>


/*
 * The message payload transferred by XPC.
 *
 * buf_pa is the physical address where the DMA should pull from.
 *
 * NOTE: for performance reasons, buf_pa should _ALWAYS_ begin on a
 * cacheline boundary.  To accomplish this, we record the number of
 * bytes from the beginning of the first cacheline to the first useful
 * byte of the skb (leadin_ignore) and the number of bytes from the
 * last useful byte of the skb to the end of the last cacheline
 * (tailout_ignore).
 *
 * size is the number of bytes to transfer which includes the skb->len
 * (useful bytes of the senders skb) plus the leadin and tailout
 */
struct xpnet_message {
      u16 version;            /* Version for this message */
      u16 embedded_bytes;     /* #of bytes embedded in XPC message */
      u32 magic;        /* Special number indicating this is xpnet */
      u64 buf_pa;       /* phys address of buffer to retrieve */
      u32 size;         /* #of bytes in buffer */
      u8 leadin_ignore; /* #of bytes to ignore at the beginning */
      u8 tailout_ignore;      /* #of bytes to ignore at the end */
      unsigned char data;     /* body of small packets */
};

/*
 * Determine the size of our message, the cacheline aligned size,
 * and then the number of message will request from XPC.
 *
 * XPC expects each message to exist in an individual cacheline.
 */
#define XPNET_MSG_SIZE        (L1_CACHE_BYTES - XPC_MSG_PAYLOAD_OFFSET)
#define XPNET_MSG_DATA_MAX    \
            (XPNET_MSG_SIZE - (u64)(&((struct xpnet_message *)0)->data))
#define XPNET_MSG_ALIGNED_SIZE      (L1_CACHE_ALIGN(XPNET_MSG_SIZE))
#define XPNET_MSG_NENTRIES    (PAGE_SIZE / XPNET_MSG_ALIGNED_SIZE)


#define XPNET_MAX_KTHREADS    (XPNET_MSG_NENTRIES + 1)
#define XPNET_MAX_IDLE_KTHREADS     (XPNET_MSG_NENTRIES + 1)

/*
 * Version number of XPNET implementation. XPNET can always talk to versions
 * with same major #, and never talk to versions with a different version.
 */
#define _XPNET_VERSION(_major, _minor)    (((_major) << 4) | (_minor))
#define XPNET_VERSION_MAJOR(_v)           ((_v) >> 4)
#define XPNET_VERSION_MINOR(_v)           ((_v) & 0xf)

#define     XPNET_VERSION _XPNET_VERSION(1,0)         /* version 1.0 */
#define     XPNET_VERSION_EMBED _XPNET_VERSION(1,1)         /* version 1.1 */
#define XPNET_MAGIC     0x88786984 /* "XNET" */

#define XPNET_VALID_MSG(_m)                                      \
   ((XPNET_VERSION_MAJOR(_m->version) == XPNET_VERSION_MAJOR(XPNET_VERSION)) \
    && (msg->magic == XPNET_MAGIC))

#define XPNET_DEVICE_NAME           "xp0"


/*
 * When messages are queued with xpc_send_notify, a kmalloc'd buffer
 * of the following type is passed as a notification cookie.  When the
 * notification function is called, we use the cookie to decide
 * whether all outstanding message sends have completed.  The skb can
 * then be released.
 */
struct xpnet_pending_msg {
      struct list_head free_list;
      struct sk_buff *skb;
      atomic_t use_count;
};

/* driver specific structure pointed to by the device structure */
struct xpnet_dev_private {
      struct net_device_stats stats;
};

struct net_device *xpnet_device;

/*
 * When we are notified of other partitions activating, we add them to
 * our bitmask of partitions to which we broadcast.
 */
static u64 xpnet_broadcast_partitions;
/* protect above */
static DEFINE_SPINLOCK(xpnet_broadcast_lock);

/*
 * Since the Block Transfer Engine (BTE) is being used for the transfer
 * and it relies upon cache-line size transfers, we need to reserve at
 * least one cache-line for head and tail alignment.  The BTE is
 * limited to 8MB transfers.
 *
 * Testing has shown that changing MTU to greater than 64KB has no effect
 * on TCP as the two sides negotiate a Max Segment Size that is limited
 * to 64K.  Other protocols May use packets greater than this, but for
 * now, the default is 64KB.
 */
#define XPNET_MAX_MTU (0x800000UL - L1_CACHE_BYTES)
/* 32KB has been determined to be the ideal */
#define XPNET_DEF_MTU (0x8000UL)


/*
 * The partition id is encapsulated in the MAC address.  The following
 * define locates the octet the partid is in.
 */
#define XPNET_PARTID_OCTET    1
#define XPNET_LICENSE_OCTET   2


/*
 * Define the XPNET debug device structure that is to be used with dev_dbg(),
 * dev_err(), dev_warn(), and dev_info().
 */
struct device_driver xpnet_dbg_name = {
      .name = "xpnet"
};

struct device xpnet_dbg_subname = {
      .bus_id = {0},                /* set to "" */
      .driver = &xpnet_dbg_name
};

struct device *xpnet = &xpnet_dbg_subname;

/*
 * Packet was recevied by XPC and forwarded to us.
 */
static void
xpnet_receive(partid_t partid, int channel, struct xpnet_message *msg)
{
      struct sk_buff *skb;
      bte_result_t bret;
      struct xpnet_dev_private *priv =
            (struct xpnet_dev_private *) xpnet_device->priv;


      if (!XPNET_VALID_MSG(msg)) {
            /*
             * Packet with a different XPC version.  Ignore.
             */
            xpc_received(partid, channel, (void *) msg);

            priv->stats.rx_errors++;

            return;
      }
      dev_dbg(xpnet, "received 0x%lx, %d, %d, %d\n", msg->buf_pa, msg->size,
            msg->leadin_ignore, msg->tailout_ignore);


      /* reserve an extra cache line */
      skb = dev_alloc_skb(msg->size + L1_CACHE_BYTES);
      if (!skb) {
            dev_err(xpnet, "failed on dev_alloc_skb(%d)\n",
                  msg->size + L1_CACHE_BYTES);

            xpc_received(partid, channel, (void *) msg);

            priv->stats.rx_errors++;

            return;
      }

      /*
       * The allocated skb has some reserved space.
       * In order to use bte_copy, we need to get the
       * skb->data pointer moved forward.
       */
      skb_reserve(skb, (L1_CACHE_BYTES - ((u64)skb->data &
                                  (L1_CACHE_BYTES - 1)) +
                    msg->leadin_ignore));

      /*
       * Update the tail pointer to indicate data actually
       * transferred.
       */
      skb_put(skb, (msg->size - msg->leadin_ignore - msg->tailout_ignore));

      /*
       * Move the data over from the other side.
       */
      if ((XPNET_VERSION_MINOR(msg->version) == 1) &&
                                    (msg->embedded_bytes != 0)) {
            dev_dbg(xpnet, "copying embedded message. memcpy(0x%p, 0x%p, "
                  "%lu)\n", skb->data, &msg->data,
                  (size_t) msg->embedded_bytes);

            skb_copy_to_linear_data(skb, &msg->data, (size_t)msg->embedded_bytes);
      } else {
            dev_dbg(xpnet, "transferring buffer to the skb->data area;\n\t"
                  "bte_copy(0x%p, 0x%p, %hu)\n", (void *)msg->buf_pa,
                  (void *)__pa((u64)skb->data & ~(L1_CACHE_BYTES - 1)),
                  msg->size);

            bret = bte_copy(msg->buf_pa,
                        __pa((u64)skb->data & ~(L1_CACHE_BYTES - 1)),
                        msg->size, (BTE_NOTIFY | BTE_WACQUIRE), NULL);

            if (bret != BTE_SUCCESS) {
                  // >>> Need better way of cleaning skb.  Currently skb
                  // >>> appears in_use and we can't just call
                  // >>> dev_kfree_skb.
                  dev_err(xpnet, "bte_copy(0x%p, 0x%p, 0x%hx) returned "
                        "error=0x%x\n", (void *)msg->buf_pa,
                        (void *)__pa((u64)skb->data &
                                          ~(L1_CACHE_BYTES - 1)),
                        msg->size, bret);

                  xpc_received(partid, channel, (void *) msg);

                  priv->stats.rx_errors++;

                  return;
            }
      }

      dev_dbg(xpnet, "<skb->head=0x%p skb->data=0x%p skb->tail=0x%p "
            "skb->end=0x%p skb->len=%d\n", (void *) skb->head,
            (void *)skb->data, skb_tail_pointer(skb), skb_end_pointer(skb),
            skb->len);

      skb->protocol = eth_type_trans(skb, xpnet_device);
      skb->ip_summed = CHECKSUM_UNNECESSARY;

      dev_dbg(xpnet, "passing skb to network layer\n"
            KERN_DEBUG "\tskb->head=0x%p skb->data=0x%p skb->tail=0x%p "
            "skb->end=0x%p skb->len=%d\n",
            (void *)skb->head, (void *)skb->data, skb_tail_pointer(skb),
            skb_end_pointer(skb), skb->len);


      xpnet_device->last_rx = jiffies;
      priv->stats.rx_packets++;
      priv->stats.rx_bytes += skb->len + ETH_HLEN;

      netif_rx_ni(skb);
      xpc_received(partid, channel, (void *) msg);
}


/*
 * This is the handler which XPC calls during any sort of change in
 * state or message reception on a connection.
 */
static void
xpnet_connection_activity(enum xpc_retval reason, partid_t partid, int channel,
                    void *data, void *key)
{
      long bp;


      DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
      DBUG_ON(channel != XPC_NET_CHANNEL);

      switch(reason) {
      case xpcMsgReceived:    /* message received */
            DBUG_ON(data == NULL);

            xpnet_receive(partid, channel, (struct xpnet_message *) data);
            break;

      case xpcConnected:      /* connection completed to a partition */
            spin_lock_bh(&xpnet_broadcast_lock);
            xpnet_broadcast_partitions |= 1UL << (partid -1 );
            bp = xpnet_broadcast_partitions;
            spin_unlock_bh(&xpnet_broadcast_lock);

            netif_carrier_on(xpnet_device);

            dev_dbg(xpnet, "%s connection created to partition %d; "
                  "xpnet_broadcast_partitions=0x%lx\n",
                  xpnet_device->name, partid, bp);
            break;

      default:
            spin_lock_bh(&xpnet_broadcast_lock);
            xpnet_broadcast_partitions &= ~(1UL << (partid -1 ));
            bp = xpnet_broadcast_partitions;
            spin_unlock_bh(&xpnet_broadcast_lock);

            if (bp == 0) {
                  netif_carrier_off(xpnet_device);
            }

            dev_dbg(xpnet, "%s disconnected from partition %d; "
                  "xpnet_broadcast_partitions=0x%lx\n",
                  xpnet_device->name, partid, bp);
            break;

      }
}


static int
xpnet_dev_open(struct net_device *dev)
{
      enum xpc_retval ret;


      dev_dbg(xpnet, "calling xpc_connect(%d, 0x%p, NULL, %ld, %ld, %ld, "
            "%ld)\n", XPC_NET_CHANNEL, xpnet_connection_activity,
            XPNET_MSG_SIZE, XPNET_MSG_NENTRIES, XPNET_MAX_KTHREADS,
            XPNET_MAX_IDLE_KTHREADS);

      ret = xpc_connect(XPC_NET_CHANNEL, xpnet_connection_activity, NULL,
                    XPNET_MSG_SIZE, XPNET_MSG_NENTRIES,
                    XPNET_MAX_KTHREADS, XPNET_MAX_IDLE_KTHREADS);
      if (ret != xpcSuccess) {
            dev_err(xpnet, "ifconfig up of %s failed on XPC connect, "
                  "ret=%d\n", dev->name, ret);

            return -ENOMEM;
      }

      dev_dbg(xpnet, "ifconfig up of %s; XPC connected\n", dev->name);

      return 0;
}


static int
xpnet_dev_stop(struct net_device *dev)
{
      xpc_disconnect(XPC_NET_CHANNEL);

      dev_dbg(xpnet, "ifconfig down of %s; XPC disconnected\n", dev->name);

      return 0;
}


static int
xpnet_dev_change_mtu(struct net_device *dev, int new_mtu)
{
      /* 68 comes from min TCP+IP+MAC header */
      if ((new_mtu < 68) || (new_mtu > XPNET_MAX_MTU)) {
            dev_err(xpnet, "ifconfig %s mtu %d failed; value must be "
                  "between 68 and %ld\n", dev->name, new_mtu,
                  XPNET_MAX_MTU);
            return -EINVAL;
      }

      dev->mtu = new_mtu;
      dev_dbg(xpnet, "ifconfig %s mtu set to %d\n", dev->name, new_mtu);
      return 0;
}


/*
 * Required for the net_device structure.
 */
static int
xpnet_dev_set_config(struct net_device *dev, struct ifmap *new_map)
{
      return 0;
}


/*
 * Return statistics to the caller.
 */
static struct net_device_stats *
xpnet_dev_get_stats(struct net_device *dev)
{
      struct xpnet_dev_private *priv;


      priv = (struct xpnet_dev_private *) dev->priv;

      return &priv->stats;
}


/*
 * Notification that the other end has received the message and
 * DMA'd the skb information.  At this point, they are done with
 * our side.  When all recipients are done processing, we
 * release the skb and then release our pending message structure.
 */
static void
xpnet_send_completed(enum xpc_retval reason, partid_t partid, int channel,
                  void *__qm)
{
      struct xpnet_pending_msg *queued_msg =
            (struct xpnet_pending_msg *) __qm;


      DBUG_ON(queued_msg == NULL);

      dev_dbg(xpnet, "message to %d notified with reason %d\n",
            partid, reason);

      if (atomic_dec_return(&queued_msg->use_count) == 0) {
            dev_dbg(xpnet, "all acks for skb->head=-x%p\n",
                  (void *) queued_msg->skb->head);

            dev_kfree_skb_any(queued_msg->skb);
            kfree(queued_msg);
      }
}


/*
 * Network layer has formatted a packet (skb) and is ready to place it
 * "on the wire".  Prepare and send an xpnet_message to all partitions
 * which have connected with us and are targets of this packet.
 *
 * MAC-NOTE:  For the XPNET driver, the MAC address contains the
 * destination partition_id.  If the destination partition id word
 * is 0xff, this packet is to broadcast to all partitions.
 */
static int
xpnet_dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
      struct xpnet_pending_msg *queued_msg;
      enum xpc_retval ret;
      struct xpnet_message *msg;
      u64 start_addr, end_addr;
      long dp;
      u8 second_mac_octet;
      partid_t dest_partid;
      struct xpnet_dev_private *priv;
      u16 embedded_bytes;


      priv = (struct xpnet_dev_private *) dev->priv;


      dev_dbg(xpnet, ">skb->head=0x%p skb->data=0x%p skb->tail=0x%p "
            "skb->end=0x%p skb->len=%d\n", (void *) skb->head,
            (void *)skb->data, skb_tail_pointer(skb), skb_end_pointer(skb),
            skb->len);


      /*
       * The xpnet_pending_msg tracks how many outstanding
       * xpc_send_notifies are relying on this skb.  When none
       * remain, release the skb.
       */
      queued_msg = kmalloc(sizeof(struct xpnet_pending_msg), GFP_ATOMIC);
      if (queued_msg == NULL) {
            dev_warn(xpnet, "failed to kmalloc %ld bytes; dropping "
                  "packet\n", sizeof(struct xpnet_pending_msg));

            priv->stats.tx_errors++;

            return -ENOMEM;
      }


      /* get the beginning of the first cacheline and end of last */
      start_addr = ((u64) skb->data & ~(L1_CACHE_BYTES - 1));
      end_addr = L1_CACHE_ALIGN((u64)skb_tail_pointer(skb));

      /* calculate how many bytes to embed in the XPC message */
      embedded_bytes = 0;
      if (unlikely(skb->len <= XPNET_MSG_DATA_MAX)) {
            /* skb->data does fit so embed */
            embedded_bytes = skb->len;
      }


      /*
       * Since the send occurs asynchronously, we set the count to one
       * and begin sending.  Any sends that happen to complete before
       * we are done sending will not free the skb.  We will be left
       * with that task during exit.  This also handles the case of
       * a packet destined for a partition which is no longer up.
       */
      atomic_set(&queued_msg->use_count, 1);
      queued_msg->skb = skb;


      second_mac_octet = skb->data[XPNET_PARTID_OCTET];
      if (second_mac_octet == 0xff) {
            /* we are being asked to broadcast to all partitions */
            dp = xpnet_broadcast_partitions;
      } else if (second_mac_octet != 0) {
            dp = xpnet_broadcast_partitions &
                              (1UL << (second_mac_octet - 1));
      } else {
            /* 0 is an invalid partid.  Ignore */
            dp = 0;
      }
      dev_dbg(xpnet, "destination Partitions mask (dp) = 0x%lx\n", dp);

      /*
       * If we wanted to allow promiscuous mode to work like an
       * unswitched network, this would be a good point to OR in a
       * mask of partitions which should be receiving all packets.
       */

      /*
       * Main send loop.
       */
      for (dest_partid = 1; dp && dest_partid < XP_MAX_PARTITIONS;
           dest_partid++) {


            if (!(dp & (1UL << (dest_partid - 1)))) {
                  /* not destined for this partition */
                  continue;
            }

            /* remove this partition from the destinations mask */
            dp &= ~(1UL << (dest_partid - 1));


            /* found a partition to send to */

            ret = xpc_allocate(dest_partid, XPC_NET_CHANNEL,
                           XPC_NOWAIT, (void **)&msg);
            if (unlikely(ret != xpcSuccess)) {
                  continue;
            }

            msg->embedded_bytes = embedded_bytes;
            if (unlikely(embedded_bytes != 0)) {
                  msg->version = XPNET_VERSION_EMBED;
                  dev_dbg(xpnet, "calling memcpy(0x%p, 0x%p, 0x%lx)\n",
                        &msg->data, skb->data, (size_t) embedded_bytes);
                  skb_copy_from_linear_data(skb, &msg->data,
                                      (size_t)embedded_bytes);
            } else {
                  msg->version = XPNET_VERSION;
            }
            msg->magic = XPNET_MAGIC;
            msg->size = end_addr - start_addr;
            msg->leadin_ignore = (u64) skb->data - start_addr;
            msg->tailout_ignore = end_addr - (u64)skb_tail_pointer(skb);
            msg->buf_pa = __pa(start_addr);

            dev_dbg(xpnet, "sending XPC message to %d:%d\n"
                  KERN_DEBUG "msg->buf_pa=0x%lx, msg->size=%u, "
                  "msg->leadin_ignore=%u, msg->tailout_ignore=%u\n",
                  dest_partid, XPC_NET_CHANNEL, msg->buf_pa, msg->size,
                  msg->leadin_ignore, msg->tailout_ignore);


            atomic_inc(&queued_msg->use_count);

            ret = xpc_send_notify(dest_partid, XPC_NET_CHANNEL, msg,
                              xpnet_send_completed, queued_msg);
            if (unlikely(ret != xpcSuccess)) {
                  atomic_dec(&queued_msg->use_count);
                  continue;
            }

      }

      if (atomic_dec_return(&queued_msg->use_count) == 0) {
            dev_dbg(xpnet, "no partitions to receive packet destined for "
                  "%d\n", dest_partid);


            dev_kfree_skb(skb);
            kfree(queued_msg);
      }

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

      return 0;
}


/*
 * Deal with transmit timeouts coming from the network layer.
 */
static void
xpnet_dev_tx_timeout (struct net_device *dev)
{
      struct xpnet_dev_private *priv;


      priv = (struct xpnet_dev_private *) dev->priv;

      priv->stats.tx_errors++;
      return;
}


static int __init
xpnet_init(void)
{
      int i;
      u32 license_num;
      int result = -ENOMEM;


      if (!ia64_platform_is("sn2")) {
            return -ENODEV;
      }

      dev_info(xpnet, "registering network device %s\n", XPNET_DEVICE_NAME);

      /*
       * use ether_setup() to init the majority of our device
       * structure and then override the necessary pieces.
       */
      xpnet_device = alloc_netdev(sizeof(struct xpnet_dev_private),
                            XPNET_DEVICE_NAME, ether_setup);
      if (xpnet_device == NULL) {
            return -ENOMEM;
      }

      netif_carrier_off(xpnet_device);

      xpnet_device->mtu = XPNET_DEF_MTU;
      xpnet_device->change_mtu = xpnet_dev_change_mtu;
      xpnet_device->open = xpnet_dev_open;
      xpnet_device->get_stats = xpnet_dev_get_stats;
      xpnet_device->stop = xpnet_dev_stop;
      xpnet_device->hard_start_xmit = xpnet_dev_hard_start_xmit;
      xpnet_device->tx_timeout = xpnet_dev_tx_timeout;
      xpnet_device->set_config = xpnet_dev_set_config;

      /*
       * Multicast assumes the LSB of the first octet is set for multicast
       * MAC addresses.  We chose the first octet of the MAC to be unlikely
       * to collide with any vendor's officially issued MAC.
       */
      xpnet_device->dev_addr[0] = 0xfe;
      xpnet_device->dev_addr[XPNET_PARTID_OCTET] = sn_partition_id;
      license_num = sn_partition_serial_number_val();
      for (i = 3; i >= 0; i--) {
            xpnet_device->dev_addr[XPNET_LICENSE_OCTET + i] =
                                          license_num & 0xff;
            license_num = license_num >> 8;
      }

      /*
       * ether_setup() sets this to a multicast device.  We are
       * really not supporting multicast at this time.
       */
      xpnet_device->flags &= ~IFF_MULTICAST;

      /*
       * No need to checksum as it is a DMA transfer.  The BTE will
       * report an error if the data is not retrievable and the
       * packet will be dropped.
       */
      xpnet_device->features = NETIF_F_NO_CSUM;

      result = register_netdev(xpnet_device);
      if (result != 0) {
            free_netdev(xpnet_device);
      }

      return result;
}
module_init(xpnet_init);


static void __exit
xpnet_exit(void)
{
      dev_info(xpnet, "unregistering network device %s\n",
            xpnet_device[0].name);

      unregister_netdev(xpnet_device);

      free_netdev(xpnet_device);
}
module_exit(xpnet_exit);


MODULE_AUTHOR("Silicon Graphics, Inc.");
MODULE_DESCRIPTION("Cross Partition Network adapter (XPNET)");
MODULE_LICENSE("GPL");


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