Phonet: implement GPRS virtual interface over PEP socket

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 347 insertions, 0 deletions

diff --git a/net/phonet/pep-gprs.c b/net/phonet/pep-gprs.c
new file mode 100644
index 000000000000..9978afbd9f2a
--- /dev/null
+++ b/net/phonet/pep-gprs.c
@@ -0,0 +1,347 @@
+/*
+ * File: pep-gprs.c
+ *
+ * GPRS over Phonet pipe end point socket
+ *
+ * Copyright (C) 2008 Nokia Corporation.
+ *
+ * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/if_ether.h>
+#include <linux/if_arp.h>
+#include <net/sock.h>
+
+#include <linux/if_phonet.h>
+#include <net/tcp_states.h>
+#include <net/phonet/gprs.h>
+
+#define GPRS_DEFAULT_MTU 1400
+
+struct gprs_dev {
+        struct sock             *sk;
+        void                    (*old_state_change)(struct sock *);
+        void                    (*old_data_ready)(struct sock *, int);
+        void                    (*old_write_space)(struct sock *);
+
+        struct net_device       *net;
+        struct net_device_stats stats;
+
+        struct sk_buff_head     tx_queue;
+        struct work_struct      tx_work;
+        spinlock_t              tx_lock;
+        unsigned                tx_max;
+};
+
+static int gprs_type_trans(struct sk_buff *skb)
+{
+        const u8 *pvfc;
+        u8 buf;
+
+        pvfc = skb_header_pointer(skb, 0, 1, &buf);
+        if (!pvfc)
+                return 0;
+        /* Look at IP version field */
+        switch (*pvfc >> 4) {
+        case 4:
+                return htons(ETH_P_IP);
+        case 6:
+                return htons(ETH_P_IPV6);
+        }
+        return 0;
+}
+
+/*
+ * Socket callbacks
+ */
+
+static void gprs_state_change(struct sock *sk)
+{
+        struct gprs_dev *dev = sk->sk_user_data;
+
+        if (sk->sk_state == TCP_CLOSE_WAIT) {
+                netif_stop_queue(dev->net);
+                netif_carrier_off(dev->net);
+        }
+}
+
+static int gprs_recv(struct gprs_dev *dev, struct sk_buff *skb)
+{
+        int err = 0;
+        u16 protocol = gprs_type_trans(skb);
+
+        if (!protocol) {
+                err = -EINVAL;
+                goto drop;
+        }
+
+        if (likely(skb_headroom(skb) & 3)) {
+                struct sk_buff *rskb, *fs;
+                int flen = 0;
+
+                /* Phonet Pipe data header is misaligned (3 bytes),
+                 * so wrap the IP packet as a single fragment of an head-less
+                 * socket buffer. The network stack will pull what it needs,
+                 * but at least, the whole IP payload is not memcpy'd. */
+                rskb = netdev_alloc_skb(dev->net, 0);
+                if (!rskb) {
+                        err = -ENOBUFS;
+                        goto drop;
+                }
+                skb_shinfo(rskb)->frag_list = skb;
+                rskb->len += skb->len;
+                rskb->data_len += rskb->len;
+                rskb->truesize += rskb->len;
+
+                /* Avoid nested fragments */
+                for (fs = skb_shinfo(skb)->frag_list; fs; fs = fs->next)
+                        flen += fs->len;
+                skb->next = skb_shinfo(skb)->frag_list;
+                skb_shinfo(skb)->frag_list = NULL;
+                skb->len -= flen;
+                skb->data_len -= flen;
+                skb->truesize -= flen;
+
+                skb = rskb;
+        }
+
+        skb->protocol = protocol;
+        skb_reset_mac_header(skb);
+        skb->dev = dev->net;
+
+        if (likely(dev->net->flags & IFF_UP)) {
+                dev->stats.rx_packets++;
+                dev->stats.rx_bytes += skb->len;
+                netif_rx(skb);
+                skb = NULL;
+        } else
+                err = -ENODEV;
+
+drop:
+        if (skb) {
+                dev_kfree_skb(skb);
+                dev->stats.rx_dropped++;
+        }
+        return err;
+}
+
+static void gprs_data_ready(struct sock *sk, int len)
+{
+        struct gprs_dev *dev = sk->sk_user_data;
+        struct sk_buff *skb;
+
+        while ((skb = pep_read(sk)) != NULL) {
+                skb_orphan(skb);
+                gprs_recv(dev, skb);
+        }
+}
+
+static void gprs_write_space(struct sock *sk)
+{
+        struct gprs_dev *dev = sk->sk_user_data;
+        unsigned credits = pep_writeable(sk);
+
+        spin_lock_bh(&dev->tx_lock);
+        dev->tx_max = credits;
+        if (credits > skb_queue_len(&dev->tx_queue))
+                netif_wake_queue(dev->net);
+        spin_unlock_bh(&dev->tx_lock);
+}
+
+/*
+ * Network device callbacks
+ */
+
+static int gprs_xmit(struct sk_buff *skb, struct net_device *net)
+{
+        struct gprs_dev *dev = netdev_priv(net);
+
+        switch (skb->protocol) {
+        case  htons(ETH_P_IP):
+        case  htons(ETH_P_IPV6):
+                break;
+        default:
+                dev_kfree_skb(skb);
+                return 0;
+        }
+
+        spin_lock(&dev->tx_lock);
+        if (likely(skb_queue_len(&dev->tx_queue) < dev->tx_max)) {
+                skb_queue_tail(&dev->tx_queue, skb);
+                skb = NULL;
+        }
+        if (skb_queue_len(&dev->tx_queue) >= dev->tx_max)
+                netif_stop_queue(net);
+        spin_unlock(&dev->tx_lock);
+
+        schedule_work(&dev->tx_work);
+        if (unlikely(skb))
+                dev_kfree_skb(skb);
+        return 0;
+}
+
+static void gprs_tx(struct work_struct *work)
+{
+        struct gprs_dev *dev = container_of(work, struct gprs_dev, tx_work);
+        struct sock *sk = dev->sk;
+        struct sk_buff *skb;
+
+        while ((skb = skb_dequeue(&dev->tx_queue)) != NULL) {
+                int err;
+
+                dev->stats.tx_bytes += skb->len;
+                dev->stats.tx_packets++;
+
+                skb_orphan(skb);
+                skb_set_owner_w(skb, sk);
+
+                lock_sock(sk);
+                err = pep_write(sk, skb);
+                if (err) {
+                        LIMIT_NETDEBUG(KERN_WARNING"%s: TX error (%d)\n",
+                                        dev->net->name, err);
+                        dev->stats.tx_aborted_errors++;
+                        dev->stats.tx_errors++;
+                }
+                release_sock(sk);
+        }
+
+        lock_sock(sk);
+        gprs_write_space(sk);
+        release_sock(sk);
+}
+
+static int gprs_set_mtu(struct net_device *net, int new_mtu)
+{
+        if ((new_mtu < 576) || (new_mtu > (PHONET_MAX_MTU - 11)))
+                return -EINVAL;
+
+        net->mtu = new_mtu;
+        return 0;
+}
+
+static struct net_device_stats *gprs_get_stats(struct net_device *net)
+{
+        struct gprs_dev *dev = netdev_priv(net);
+
+        return &dev->stats;
+}
+
+static void gprs_setup(struct net_device *net)
+{
+        net->features           = NETIF_F_FRAGLIST;
+        net->type               = ARPHRD_NONE;
+        net->flags              = IFF_POINTOPOINT | IFF_NOARP;
+        net->mtu                = GPRS_DEFAULT_MTU;
+        net->hard_header_len    = 0;
+        net->addr_len           = 0;
+        net->tx_queue_len       = 10;
+
+        net->destructor         = free_netdev;
+        net->hard_start_xmit    = gprs_xmit; /* mandatory */
+        net->change_mtu         = gprs_set_mtu;
+        net->get_stats          = gprs_get_stats;
+}
+
+/*
+ * External interface
+ */
+
+/*
+ * Attach a GPRS interface to a datagram socket.
+ * Returns the interface index on success, negative error code on error.
+ */
+int gprs_attach(struct sock *sk)
+{
+        static const char ifname[] = "gprs%d";
+        struct gprs_dev *dev;
+        struct net_device *net;
+        int err;
+
+        if (unlikely(sk->sk_type == SOCK_STREAM))
+                return -EINVAL; /* need packet boundaries */
+
+        /* Create net device */
+        net = alloc_netdev(sizeof(*dev), ifname, gprs_setup);
+        if (!net)
+                return -ENOMEM;
+        dev = netdev_priv(net);
+        dev->net = net;
+        dev->tx_max = 0;
+        spin_lock_init(&dev->tx_lock);
+        skb_queue_head_init(&dev->tx_queue);
+        INIT_WORK(&dev->tx_work, gprs_tx);
+
+        netif_stop_queue(net);
+        err = register_netdev(net);
+        if (err) {
+                free_netdev(net);
+                return err;
+        }
+
+        lock_sock(sk);
+        if (unlikely(sk->sk_user_data)) {
+                err = -EBUSY;
+                goto out_rel;
+        }
+        if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
+                        sock_flag(sk, SOCK_DEAD))) {
+                err = -EINVAL;
+                goto out_rel;
+        }
+        sk->sk_user_data        = dev;
+        dev->old_state_change   = sk->sk_state_change;
+        dev->old_data_ready     = sk->sk_data_ready;
+        dev->old_write_space    = sk->sk_write_space;
+        sk->sk_state_change     = gprs_state_change;
+        sk->sk_data_ready       = gprs_data_ready;
+        sk->sk_write_space      = gprs_write_space;
+        release_sock(sk);
+
+        sock_hold(sk);
+        dev->sk = sk;
+
+        printk(KERN_DEBUG"%s: attached\n", net->name);
+        gprs_write_space(sk); /* kick off TX */
+        return net->ifindex;
+
+out_rel:
+        release_sock(sk);
+        unregister_netdev(net);
+        return err;
+}
+
+void gprs_detach(struct sock *sk)
+{
+        struct gprs_dev *dev = sk->sk_user_data;
+        struct net_device *net = dev->net;
+
+        lock_sock(sk);
+        sk->sk_user_data        = NULL;
+        sk->sk_state_change     = dev->old_state_change;
+        sk->sk_data_ready       = dev->old_data_ready;
+        sk->sk_write_space      = dev->old_write_space;
+        release_sock(sk);
+
+        printk(KERN_DEBUG"%s: detached\n", net->name);
+        unregister_netdev(net);
+        flush_scheduled_work();
+        sock_put(sk);
+        skb_queue_purge(&dev->tx_queue);
+}