text: /*
   * 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) 1999-2009 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/slab.h>
  #include <linux/module.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include "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 */
  	unsigned long 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		XPC_MSG_PAYLOAD_MAX_SIZE
  #define XPNET_MSG_DATA_MAX	\
  		(XPNET_MSG_SIZE - offsetof(struct xpnet_message, data))
  #define XPNET_MSG_NENTRIES	(PAGE_SIZE / XPC_MSG_MAX_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 sk_buff *skb;
  	atomic_t use_count;
  };
  
  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 unsigned long *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)
  /* 68 comes from min TCP+IP+MAC header */
  #define XPNET_MIN_MTU 68
  /* 32KB has been determined to be the ideal */
  #define XPNET_DEF_MTU (0x8000UL)
  
  /*
   * The partid is encapsulated in the MAC address beginning in the following
   * octet and it consists of two octets.
   */
  #define XPNET_PARTID_OCTET	2
  
  /* Define the XPNET debug device structures to be used with dev_dbg() et al */
  
  struct device_driver xpnet_dbg_name = {
  	.name = "xpnet"
  };
  
  struct device xpnet_dbg_subname = {
  	.init_name = "",	/* 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(short partid, int channel, struct xpnet_message *msg)
  {
  	struct sk_buff *skb;
  	void *dst;
  	enum xp_retval ret;
  
  	if (!XPNET_VALID_MSG(msg)) {
  		/*
  		 * Packet with a different XPC version.  Ignore.
  		 */
  		xpc_received(partid, channel, (void *)msg);
  
  		xpnet_device->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);
  
  		xpnet_device->stats.rx_errors++;
  
  		return;
  	}
  
  	/*
  	 * The allocated skb has some reserved space.
  	 * In order to use xp_remote_memcpy(), 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 {
  		dst = (void *)((u64)skb->data & ~(L1_CACHE_BYTES - 1));
  		dev_dbg(xpnet, "transferring buffer to the skb->data area;\n\t"
  			"xp_remote_memcpy(0x%p, 0x%p, %hu)\n", dst,
  					  (void *)msg->buf_pa, msg->size);
  
  		ret = xp_remote_memcpy(xp_pa(dst), msg->buf_pa, msg->size);
  		if (ret != xpSuccess) {
  			/*
  			 * !!! Need better way of cleaning skb.  Currently skb
  			 * !!! appears in_use and we can't just call
  			 * !!! dev_kfree_skb.
  			 */
  			dev_err(xpnet, "xp_remote_memcpy(0x%p, 0x%p, 0x%hx) "
  				"returned error=0x%x\n", dst,
  				(void *)msg->buf_pa, msg->size, ret);
  
  			xpc_received(partid, channel, (void *)msg);
  
  			xpnet_device->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"
  		"\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->stats.rx_packets++;
  	xpnet_device->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 xp_retval reason, short partid, int channel,
  			  void *data, void *key)
  {
  	DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
  	DBUG_ON(channel != XPC_NET_CHANNEL);
  
  	switch (reason) {
  	case xpMsgReceived:	/* message received */
  		DBUG_ON(data == NULL);
  
  		xpnet_receive(partid, channel, (struct xpnet_message *)data);
  		break;
  
  	case xpConnected:	/* connection completed to a partition */
  		spin_lock_bh(&xpnet_broadcast_lock);
  		__set_bit(partid, xpnet_broadcast_partitions);
  		spin_unlock_bh(&xpnet_broadcast_lock);
  
  		netif_carrier_on(xpnet_device);
  
  		dev_dbg(xpnet, "%s connected to partition %d\n",
  			xpnet_device->name, partid);
  		break;
  
  	default:
  		spin_lock_bh(&xpnet_broadcast_lock);
  		__clear_bit(partid, xpnet_broadcast_partitions);
  		spin_unlock_bh(&xpnet_broadcast_lock);
  
  		if (bitmap_empty((unsigned long *)xpnet_broadcast_partitions,
  				 xp_max_npartitions)) {
  			netif_carrier_off(xpnet_device);
  		}
  
  		dev_dbg(xpnet, "%s disconnected from partition %d\n",
  			xpnet_device->name, partid);
  		break;
  	}
  }
  
  static int
  xpnet_dev_open(struct net_device *dev)
  {
  	enum xp_retval ret;
  
  	dev_dbg(xpnet, "calling xpc_connect(%d, 0x%p, NULL, %ld, %ld, %ld, "
  		"%ld)\n", XPC_NET_CHANNEL, xpnet_connection_activity,
  		(unsigned long)XPNET_MSG_SIZE,
  		(unsigned long)XPNET_MSG_NENTRIES,
  		(unsigned long)XPNET_MAX_KTHREADS,
  		(unsigned long)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 != xpSuccess) {
  		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;
  }
  
  /*
   * 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 xp_retval reason, short 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);
  	}
  }
  
  static void
  xpnet_send(struct sk_buff *skb, struct xpnet_pending_msg *queued_msg,
  	   u64 start_addr, u64 end_addr, u16 embedded_bytes, int dest_partid)
  {
  	u8 msg_buffer[XPNET_MSG_SIZE];
  	struct xpnet_message *msg = (struct xpnet_message *)&msg_buffer;
  	u16 msg_size = sizeof(struct xpnet_message);
  	enum xp_retval ret;
  
  	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);
  		msg_size += embedded_bytes - 1;
  	} 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 = xp_pa((void *)start_addr);
  
  	dev_dbg(xpnet, "sending XPC message to %d:%d\n"
  		"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, XPC_NOWAIT, msg,
  			      msg_size, xpnet_send_completed, queued_msg);
  	if (unlikely(ret != xpSuccess))
  		atomic_dec(&queued_msg->use_count);
  }
  
  /*
   * 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 partid.  If the destination partid octets are 0xffff,
   * this packet is to be broadcast to all connected partitions.
   */
  static netdev_tx_t
  xpnet_dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct xpnet_pending_msg *queued_msg;
  	u64 start_addr, end_addr;
  	short dest_partid;
  	u16 embedded_bytes = 0;
  
  	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);
  
  	if (skb->data[0] == 0x33) {
  		dev_kfree_skb(skb);
  		return NETDEV_TX_OK;	/* nothing needed to be done */
  	}
  
  	/*
  	 * 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));
  
  		dev->stats.tx_errors++;
  		dev_kfree_skb(skb);
  		return NETDEV_TX_OK;
  	}
  
  	/* 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 */
  	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;
  
  	if (skb->data[0] == 0xff) {
  		/* we are being asked to broadcast to all partitions */
  		for_each_set_bit(dest_partid, xpnet_broadcast_partitions,
  			     xp_max_npartitions) {
  
  			xpnet_send(skb, queued_msg, start_addr, end_addr,
  				   embedded_bytes, dest_partid);
  		}
  	} else {
  		dest_partid = (short)skb->data[XPNET_PARTID_OCTET + 1];
  		dest_partid |= (short)skb->data[XPNET_PARTID_OCTET + 0] << 8;
  
  		if (dest_partid >= 0 &&
  		    dest_partid < xp_max_npartitions &&
  		    test_bit(dest_partid, xpnet_broadcast_partitions) != 0) {
  
  			xpnet_send(skb, queued_msg, start_addr, end_addr,
  				   embedded_bytes, dest_partid);
  		}
  	}
  
  	dev->stats.tx_packets++;
  	dev->stats.tx_bytes += skb->len;
  
  	if (atomic_dec_return(&queued_msg->use_count) == 0) {
  		dev_kfree_skb(skb);
  		kfree(queued_msg);
  	}
  
  	return NETDEV_TX_OK;
  }
  
  /*
   * Deal with transmit timeouts coming from the network layer.
   */
  static void
  xpnet_dev_tx_timeout(struct net_device *dev)
  {
  	dev->stats.tx_errors++;
  }
  
  static const struct net_device_ops xpnet_netdev_ops = {
  	.ndo_open		= xpnet_dev_open,
  	.ndo_stop		= xpnet_dev_stop,
  	.ndo_start_xmit		= xpnet_dev_hard_start_xmit,
  	.ndo_tx_timeout		= xpnet_dev_tx_timeout,
  	.ndo_set_mac_address 	= eth_mac_addr,
  	.ndo_validate_addr	= eth_validate_addr,
  };
  
  static int __init
  xpnet_init(void)
  {
  	int result;
  
  	if (!is_shub() && !is_uv())
  		return -ENODEV;
  
  	dev_info(xpnet, "registering network device %s\n", XPNET_DEVICE_NAME);
  
  	xpnet_broadcast_partitions = kcalloc(BITS_TO_LONGS(xp_max_npartitions),
  					     sizeof(long),
  					     GFP_KERNEL);
  	if (xpnet_broadcast_partitions == NULL)
  		return -ENOMEM;
  
  	/*
  	 * use ether_setup() to init the majority of our device
  	 * structure and then override the necessary pieces.
  	 */
  	xpnet_device = alloc_netdev(0, XPNET_DEVICE_NAME, NET_NAME_UNKNOWN,
  				    ether_setup);
  	if (xpnet_device == NULL) {
  		kfree(xpnet_broadcast_partitions);
  		return -ENOMEM;
  	}
  
  	netif_carrier_off(xpnet_device);
  
  	xpnet_device->netdev_ops = &xpnet_netdev_ops;
  	xpnet_device->mtu = XPNET_DEF_MTU;
  	xpnet_device->min_mtu = XPNET_MIN_MTU;
  	xpnet_device->max_mtu = XPNET_MAX_MTU;
  
  	/*
  	 * 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] = 0x02;     /* locally administered, no OUI */
  
  	xpnet_device->dev_addr[XPNET_PARTID_OCTET + 1] = xp_partition_id;
  	xpnet_device->dev_addr[XPNET_PARTID_OCTET + 0] = (xp_partition_id >> 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_HW_CSUM;
  
  	result = register_netdev(xpnet_device);
  	if (result != 0) {
  		free_netdev(xpnet_device);
  		kfree(xpnet_broadcast_partitions);
  	}
  
  	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);
  	kfree(xpnet_broadcast_partitions);
  }
  
  module_exit(xpnet_exit);
  
  MODULE_AUTHOR("Silicon Graphics, Inc.");
  MODULE_DESCRIPTION("Cross Partition Network adapter (XPNET)");
  MODULE_LICENSE("GPL");
  