[RFC PATCH v3 09/17] net: Add vbus_enet driver

Gregory Haskins
2009-04-21T18:43:25Z

drivers/net/Kconfig | 13 +
drivers/net/Makefile | 1
drivers/net/vbus-enet.c | 672 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 686 insertions(+), 0 deletions(-)
create mode 100644 drivers/net/vbus-enet.c

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 9e92154..f46239b 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -3155,4 +3155,17 @@ config VIRTIO_NET
This is the virtual network driver for virtio. It can be used with
lguest or QEMU based VMMs (like KVM or Xen). Say Y or M.

+config VBUS_ENET
+ tristate "Virtual Ethernet Driver"
+ depends on VBUS_DRIVERS
+ help
+ A virtualized 802.x network device based on the VBUS interface.
+ It can be used with any hypervisor/kernel that supports the
+ vbus protocol.
+
+config VBUS_ENET_DEBUG
+ bool "Enable Debugging"
+ depends on VBUS_ENET
+ default n
+
endif # NETDEVICES
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 1fc4602..ee76236 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -268,6 +268,7 @@ obj-$(CONFIG_FS_ENET) += fs_enet/
obj-$(CONFIG_NETXEN_NIC) += netxen/
obj-$(CONFIG_NIU) += niu.o
obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
+obj-$(CONFIG_VBUS_ENET) += vbus-enet.o
obj-$(CONFIG_SFC) += sfc/

obj-$(CONFIG_WIMAX) += wimax/
diff --git a/drivers/net/vbus-enet.c b/drivers/net/vbus-enet.c
new file mode 100644
index 0000000..8fcc2d6
--- /dev/null
+++ b/drivers/net/vbus-enet.c
@@ -0,0 +1,672 @@
+/*
+ * vbus_enet - A virtualized 802.x network device based on the VBUS interface
+ *
+ * Copyright (C) 2009 Novell, Gregory Haskins <ghaskins@novell.com>
+ *
+ * Derived from the SNULL example from the book "Linux Device Drivers" by
+ * Alessandro Rubini, Jonathan Corbet, and Greg Kroah-Hartman, published
+ * by O'Reilly & Associates.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+
+#include <linux/in.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/skbuff.h>
+#include <linux/ioq.h>
+#include <linux/vbus_driver.h>
+
+#include <linux/in6.h>
+#include <asm/checksum.h>
+
+#include <linux/venet.h>
+
+MODULE_AUTHOR("Gregory Haskins");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("virtual-ethernet");
+MODULE_VERSION("1");
+
+static int rx_ringlen = 256;
+module_param(rx_ringlen, int, 0444);
+static int tx_ringlen = 256;
+module_param(tx_ringlen, int, 0444);
+
+#define PDEBUG(_dev, fmt, args...) dev_dbg(&(_dev)->dev, fmt, ## args)
+
+struct vbus_enet_queue {
+ struct ioq *queue;
+ struct ioq_notifier notifier;
+};
+
+struct vbus_enet_priv {
+ spinlock_t lock;
+ struct net_device *dev;
+ struct vbus_device_proxy *vdev;
+ struct napi_struct napi;
+ struct vbus_enet_queue rxq;
+ struct vbus_enet_queue txq;
+ struct tasklet_struct txtask;
+};
+
+static struct vbus_enet_priv *
+napi_to_priv(struct napi_struct *napi)
+{
+ return container_of(napi, struct vbus_enet_priv, napi);
+}
+
+static int
+queue_init(struct vbus_enet_priv *priv,
+ struct vbus_enet_queue *q,
+ int qid,
+ size_t ringsize,
+ void (*func)(struct ioq_notifier *))
+{
+ struct vbus_device_proxy *dev = priv->vdev;
+ int ret;
+
+ ret = vbus_driver_ioq_alloc(dev, qid, 0, ringsize, &q->queue);
+ if (ret < 0)
+ panic("ioq_alloc failed: %d\n", ret);
+
+ if (func) {
+ q->notifier.signal = func;
+ q->queue->notifier = &q->notifier;
+ }
+
+ return 0;
+}
+
+static int
+devcall(struct vbus_enet_priv *priv, u32 func, void *data, size_t len)
+{
+ struct vbus_device_proxy *dev = priv->vdev;
+
+ return dev->ops->call(dev, func, data, len, 0);
+}
+
+/*
+ * ---------------
+ * rx descriptors
+ * ---------------
+ */
+
+static void
+rxdesc_alloc(struct net_device *dev, struct ioq_ring_desc *desc, size_t len)
+{
+ struct sk_buff *skb;
+
+ len += ETH_HLEN;
+
+ skb = netdev_alloc_skb(dev, len + 2);
+ BUG_ON(!skb);
+
+ skb_reserve(skb, NET_IP_ALIGN); /* align IP on 16B boundary */
+
+ desc->cookie = (u64)skb;
+ desc->ptr = (u64)__pa(skb->data);
+ desc->len = len; /* total length */
+ desc->valid = 1;
+}
+
+static void
+rx_setup(struct vbus_enet_priv *priv)
+{
+ struct ioq *ioq = priv->rxq.queue;
+ struct ioq_iterator iter;
+ int ret;
+
+ /*
+ * We want to iterate on the "valid" index. By default the iterator
+ * will not "autoupdate" which means it will not hypercall the host
+ * with our changes. This is good, because we are really just
+ * initializing stuff here anyway. Note that you can always manually
+ * signal the host with ioq_signal() if the autoupdate feature is not
+ * used.
+ */
+ ret = ioq_iter_init(ioq, &iter, ioq_idxtype_valid, 0);
+ BUG_ON(ret < 0); /* will never fail unless seriously broken */
+
+ /*
+ * Seek to the tail of the valid index (which should be our first
+ * item, since the queue is brand-new)
+ */
+ ret = ioq_iter_seek(&iter, ioq_seek_tail, 0, 0);
+ BUG_ON(ret < 0);
+
+ /*
+ * Now populate each descriptor with an empty SKB and mark it valid
+ */
+ while (!iter.desc->valid) {
+ rxdesc_alloc(priv->dev, iter.desc, priv->dev->mtu);
+
+ /*
+ * This push operation will simultaneously advance the
+ * valid-head index and increment our position in the queue
+ * by one.
+ */
+ ret = ioq_iter_push(&iter, 0);
+ BUG_ON(ret < 0);
+ }
+}
+
+static void
+rx_teardown(struct vbus_enet_priv *priv)
+{
+ struct ioq *ioq = priv->rxq.queue;
+ struct ioq_iterator iter;
+ int ret;
+
+ ret = ioq_iter_init(ioq, &iter, ioq_idxtype_valid, 0);
+ BUG_ON(ret < 0);
+
+ ret = ioq_iter_seek(&iter, ioq_seek_head, 0, 0);
+ BUG_ON(ret < 0);
+
+ /*
+ * free each valid descriptor
+ */
+ while (iter.desc->valid) {
+ struct sk_buff *skb = (struct sk_buff *)iter.desc->cookie;
+
+ iter.desc->valid = 0;
+ wmb();
+
+ iter.desc->ptr = 0;
+ iter.desc->cookie = 0;
+
+ ret = ioq_iter_pop(&iter, 0);
+ BUG_ON(ret < 0);
+
+ dev_kfree_skb(skb);
+ }
+}
+
+/*
+ * Open and close
+ */
+
+static int
+vbus_enet_open(struct net_device *dev)
+{
+ struct vbus_enet_priv *priv = netdev_priv(dev);
+ int ret;
+
+ ret = devcall(priv, VENET_FUNC_LINKUP, NULL, 0);
+ BUG_ON(ret < 0);
+
+ napi_enable(&priv->napi);
+
+ return 0;
+}
+
+static int
+vbus_enet_stop(struct net_device *dev)
+{
+ struct vbus_enet_priv *priv = netdev_priv(dev);
+ int ret;
+
+ napi_disable(&priv->napi);
+
+ ret = devcall(priv, VENET_FUNC_LINKDOWN, NULL, 0);
+ BUG_ON(ret < 0);
+
+ return 0;
+}
+
+/*
+ * Configuration changes (passed on by ifconfig)
+ */
+static int
+vbus_enet_config(struct net_device *dev, struct ifmap *map)
+{
+ if (dev->flags & IFF_UP) /* can't act on a running interface */
+ return -EBUSY;
+
+ /* Don't allow changing the I/O address */
+ if (map->base_addr != dev->base_addr) {
+ dev_warn(&dev->dev, "Can't change I/O address\n");
+ return -EOPNOTSUPP;
+ }
+
+ /* ignore other fields */
+ return 0;
+}
+
+static void
+vbus_enet_schedule_rx(struct vbus_enet_priv *priv)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (napi_schedule_prep(&priv->napi)) {
+ /* Disable further interrupts */
+ ioq_notify_disable(priv->rxq.queue, 0);
+ __napi_schedule(&priv->napi);
+ }
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+static int
+vbus_enet_change_mtu(struct net_device *dev, int new_mtu)
+{
+ struct vbus_enet_priv *priv = netdev_priv(dev);
+ int ret;
+
+ dev->mtu = new_mtu;
+
+ /*
+ * FLUSHRX will cause the device to flush any outstanding
+ * RX buffers. They will appear to come in as 0 length
+ * packets which we can simply discard and replace with new_mtu
+ * buffers for the future.
+ */
+ ret = devcall(priv, VENET_FUNC_FLUSHRX, NULL, 0);
+ BUG_ON(ret < 0);
+
+ vbus_enet_schedule_rx(priv);
+
+ return 0;
+}
+
+/*
+ * The poll implementation.
+ */
+static int
+vbus_enet_poll(struct napi_struct *napi, int budget)
+{
+ struct vbus_enet_priv *priv = napi_to_priv(napi);
+ int npackets = 0;
+ struct ioq_iterator iter;
+ int ret;
+
+ PDEBUG(priv->dev, "polling...\n");
+
+ /* We want to iterate on the head of the in-use index */
+ ret = ioq_iter_init(priv->rxq.queue, &iter, ioq_idxtype_inuse,
+ IOQ_ITER_AUTOUPDATE);
+ BUG_ON(ret < 0);
+
+ ret = ioq_iter_seek(&iter, ioq_seek_head, 0, 0);
+ BUG_ON(ret < 0);
+
+ /*
+ * We stop if we have met the quota or there are no more packets.
+ * The EOM is indicated by finding a packet that is still owned by
+ * the south side
+ */
+ while ((npackets < budget) && (!iter.desc->sown)) {
+ struct sk_buff *skb = (struct sk_buff *)iter.desc->cookie;
+
+ if (iter.desc->len) {
+ skb_put(skb, iter.desc->len);
+
+ /* Maintain stats */
+ npackets++;
+ priv->dev->stats.rx_packets++;
+ priv->dev->stats.rx_bytes += iter.desc->len;
+
+ /* Pass the buffer up to the stack */
+ skb->dev = priv->dev;
+ skb->protocol = eth_type_trans(skb, priv->dev);
+ netif_receive_skb(skb);
+
+ mb();
+ } else
+ /*
+ * the device may send a zero-length packet when its
+ * flushing references on the ring. We can just drop
+ * these on the floor
+ */
+ dev_kfree_skb(skb);
+
+ /* Grab a new buffer to put in the ring */
+ rxdesc_alloc(priv->dev, iter.desc, priv->dev->mtu);
+
+ /* Advance the in-use tail */
+ ret = ioq_iter_pop(&iter, 0);
+ BUG_ON(ret < 0);
+ }
+
+ PDEBUG(priv->dev, "%d packets received\n", npackets);
+
+ /*
+ * If we processed all packets, we're done; tell the kernel and
+ * reenable ints
+ */
+ if (ioq_empty(priv->rxq.queue, ioq_idxtype_inuse)) {
+ napi_complete(napi);
+ ioq_notify_enable(priv->rxq.queue, 0);
+ ret = 0;
+ } else
+ /* We couldn't process everything. */
+ ret = 1;
+
+ return ret;
+}
+
+/*
+ * Transmit a packet (called by the kernel)
+ */
+static int
+vbus_enet_tx_start(struct sk_buff *skb, struct net_device *dev)
+{
+ struct vbus_enet_priv *priv = netdev_priv(dev);
+ struct ioq_iterator iter;
+ int ret;
+ unsigned long flags;
+
+ PDEBUG(priv->dev, "sending %d bytes\n", skb->len);
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (ioq_full(priv->txq.queue, ioq_idxtype_valid)) {
+ /*
+ * We must flow-control the kernel by disabling the
+ * queue
+ */
+ spin_unlock_irqrestore(&priv->lock, flags);
+ netif_stop_queue(dev);
+ dev_err(&priv->dev->dev, "tx on full queue bug\n");
+ return 1;
+ }
+
+ /*
+ * We want to iterate on the tail of both the "inuse" and "valid" index
+ * so we specify the "both" index
+ */
+ ret = ioq_iter_init(priv->txq.queue, &iter, ioq_idxtype_both,
+ IOQ_ITER_AUTOUPDATE);
+ BUG_ON(ret < 0);
+
+ ret = ioq_iter_seek(&iter, ioq_seek_tail, 0, 0);
+ BUG_ON(ret < 0);
+ BUG_ON(iter.desc->sown);
+
+ /*
+ * We simply put the skb right onto the ring. We will get an interrupt
+ * later when the data has been consumed and we can reap the pointers
+ * at that time
+ */
+ iter.desc->cookie = (u64)skb;
+ iter.desc->len = (u64)skb->len;
+ iter.desc->ptr = (u64)__pa(skb->data);
+ iter.desc->valid = 1;
+
+ priv->dev->stats.tx_packets++;
+ priv->dev->stats.tx_bytes += skb->len;
+
+ /*
+ * This advances both indexes together implicitly, and then
+ * signals the south side to consume the packet
+ */
+ ret = ioq_iter_push(&iter, 0);
+ BUG_ON(ret < 0);
+
+ dev->trans_start = jiffies; /* save the timestamp */
+
+ if (ioq_full(priv->txq.queue, ioq_idxtype_valid)) {
+ /*
+ * If the queue is congested, we must flow-control the kernel
+ */
+ PDEBUG(priv->dev, "backpressure tx queue\n");
+ netif_stop_queue(dev);
+ }
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+/*
+ * reclaim any outstanding completed tx packets
+ *
+ * assumes priv->lock held
+ */
+static void
+vbus_enet_tx_reap(struct vbus_enet_priv *priv, int force)
+{
+ struct ioq_iterator iter;
+ int ret;
+
+ /*
+ * We want to iterate on the head of the valid index, but we
+ * do not want the iter_pop (below) to flip the ownership, so
+ * we set the NOFLIPOWNER option
+ */
+ ret = ioq_iter_init(priv->txq.queue, &iter, ioq_idxtype_valid,
+ IOQ_ITER_NOFLIPOWNER);
+ BUG_ON(ret < 0);
+
+ ret = ioq_iter_seek(&iter, ioq_seek_head, 0, 0);
+ BUG_ON(ret < 0);
+
+ /*
+ * We are done once we find the first packet either invalid or still
+ * owned by the south-side
+ */
+ while (iter.desc->valid && (!iter.desc->sown || force)) {
+ struct sk_buff *skb = (struct sk_buff *)iter.desc->cookie;
+
+ PDEBUG(priv->dev, "completed sending %d bytes\n", skb->len);
+
+ /* Reset the descriptor */
+ iter.desc->valid = 0;
+
+ dev_kfree_skb(skb);
+
+ /* Advance the valid-index head */
+ ret = ioq_iter_pop(&iter, 0);
+ BUG_ON(ret < 0);
+ }
+
+ /*
+ * If we were previously stopped due to flow control, restart the
+ * processing
+ */
+ if (netif_queue_stopped(priv->dev)
+ && !ioq_full(priv->txq.queue, ioq_idxtype_valid)) {
+ PDEBUG(priv->dev, "re-enabling tx queue\n");
+ netif_wake_queue(priv->dev);
+ }
+}
+
+static void
+vbus_enet_timeout(struct net_device *dev)
+{
+ struct vbus_enet_priv *priv = netdev_priv(dev);
+ unsigned long flags;
+
+ dev_dbg(&dev->dev, "Transmit timeout\n");
+
+ spin_lock_irqsave(&priv->lock, flags);
+ vbus_enet_tx_reap(priv, 0);
+ spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+static void
+rx_isr(struct ioq_notifier *notifier)
+{
+ struct vbus_enet_priv *priv;
+ struct net_device *dev;
+
+ priv = container_of(notifier, struct vbus_enet_priv, rxq.notifier);
+ dev = priv->dev;
+
+ if (!ioq_empty(priv->rxq.queue, ioq_idxtype_inuse))
+ vbus_enet_schedule_rx(priv);
+}
+
+static void
+deferred_tx_isr(unsigned long data)
+{
+ struct vbus_enet_priv *priv = (struct vbus_enet_priv *)data;
+ unsigned long flags;
+
+ PDEBUG(priv->dev, "deferred_tx_isr\n");
+
+ spin_lock_irqsave(&priv->lock, flags);
+ vbus_enet_tx_reap(priv, 0);
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ ioq_notify_enable(priv->txq.queue, 0);
+}
+
+static void
+tx_isr(struct ioq_notifier *notifier)
+{
+ struct vbus_enet_priv *priv;
+
+ priv = container_of(notifier, struct vbus_enet_priv, txq.notifier);
+
+ PDEBUG(priv->dev, "tx_isr\n");
+
+ ioq_notify_disable(priv->txq.queue, 0);
+ tasklet_schedule(&priv->txtask);
+}
+
+static const struct net_device_ops vbus_enet_netdev_ops = {
+ .ndo_open = vbus_enet_open,
+ .ndo_stop = vbus_enet_stop,
+ .ndo_set_config = vbus_enet_config,
+ .ndo_start_xmit = vbus_enet_tx_start,
+ .ndo_change_mtu = vbus_enet_change_mtu,
+ .ndo_tx_timeout = vbus_enet_timeout,
+};
+
+/*
+ * This is called whenever a new vbus_device_proxy is added to the vbus
+ * with the matching VENET_ID
+ */
+static int
+vbus_enet_probe(struct vbus_device_proxy *vdev)
+{
+ struct net_device *dev;
+ struct vbus_enet_priv *priv;
+ int ret;
+
+ printk(KERN_INFO "VENET: Found new device at %lld\n", vdev->id);
+
+ ret = vdev->ops->open(vdev, VENET_VERSION, 0);
+ if (ret < 0)
+ return ret;
+
+ dev = alloc_etherdev(sizeof(struct vbus_enet_priv));
+ if (!dev)
+ return -ENOMEM;
+
+ priv = netdev_priv(dev);
+
+ spin_lock_init(&priv->lock);
+ priv->dev = dev;
+ priv->vdev = vdev;
+
+ tasklet_init(&priv->txtask, deferred_tx_isr, (unsigned long)priv);
+
+ queue_init(priv, &priv->rxq, VENET_QUEUE_RX, rx_ringlen, rx_isr);
+ queue_init(priv, &priv->txq, VENET_QUEUE_TX, tx_ringlen, tx_isr);
+
+ rx_setup(priv);
+
+ ioq_notify_enable(priv->rxq.queue, 0); /* enable interrupts */
+ ioq_notify_enable(priv->txq.queue, 0);
+
+ dev->netdev_ops = &vbus_enet_netdev_ops;
+ dev->watchdog_timeo = 5 * HZ;
+
+ netif_napi_add(dev, &priv->napi, vbus_enet_poll, 128);
+
+ ret = devcall(priv, VENET_FUNC_MACQUERY, priv->dev->dev_addr, ETH_ALEN);
+ if (ret < 0) {
+ printk(KERN_INFO "VENET: Error obtaining MAC address for " \
+ "%lld\n",
+ priv->vdev->id);
+ goto out_free;
+ }
+
+ dev->features |= NETIF_F_HIGHDMA;
+
+ ret = register_netdev(dev);
+ if (ret < 0) {
+ printk(KERN_INFO "VENET: error %i registering device \"%s\"\n",
+ ret, dev->name);
+ goto out_free;
+ }
+
+ vdev->priv = priv;
+
+ return 0;
+
+ out_free:
+ free_netdev(dev);
+
+ return ret;
+}
+
+static int
+vbus_enet_remove(struct vbus_device_proxy *vdev)
+{
+ struct vbus_enet_priv *priv = (struct vbus_enet_priv *)vdev->priv;
+ struct vbus_device_proxy *dev = priv->vdev;
+
+ unregister_netdev(priv->dev);
+ napi_disable(&priv->napi);
+
+ rx_teardown(priv);
+ vbus_enet_tx_reap(priv, 1);
+
+ ioq_put(priv->rxq.queue);
+ ioq_put(priv->txq.queue);
+
+ dev->ops->close(dev, 0);
+
+ free_netdev(priv->dev);
+
+ return 0;
+}
+
+/*
+ * Finally, the module stuff
+ */
+
+static struct vbus_driver_ops vbus_enet_driver_ops = {
+ .probe = vbus_enet_probe,
+ .remove = vbus_enet_remove,
+};
+
+static struct vbus_driver vbus_enet_driver = {
+ .type = VENET_TYPE,
+ .owner = THIS_MODULE,
+ .ops = &vbus_enet_driver_ops,
+};
+
+static __init int
+vbus_enet_init_module(void)
+{
+ printk(KERN_INFO "Virtual Ethernet: Copyright (C) 2009 Novell, Gregory Haskins\n");
+ printk(KERN_DEBUG "VENET: Using %d/%d queue depth\n",
+ rx_ringlen, tx_ringlen);
+ return vbus_driver_register(&vbus_enet_driver);
+}
+
+static __exit void
+vbus_enet_cleanup(void)
+{
+ vbus_driver_unregister(&vbus_enet_driver);
+}
+
+module_init(vbus_enet_init_module);
+module_exit(vbus_enet_cleanup);