xpnet.c

linux-2.6.15.6

/*
 * 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/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.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 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);

		memcpy(skb->data, &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, (void *) skb->tail, (void *) skb->end,
		skb->len);

	skb->dev = xpnet_device;
	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, (void *) skb->tail,
		(void *) skb->end, 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, %d, "
		"%d)\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);