/*
   * Copyright (C) ST-Ericsson AB 2010
   * Authors:	Sjur Brendeland/sjur.brandeland@stericsson.com
   *		Daniel Martensson / Daniel.Martensson@stericsson.com
   * License terms: GNU General Public License (GPL) version 2
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

  #include <linux/fs.h>

  #include <linux/hardirq.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netdevice.h>
  #include <linux/if_ether.h>
  #include <linux/moduleparam.h>
  #include <linux/ip.h>
  #include <linux/sched.h>
  #include <linux/sockios.h>
  #include <linux/caif/if_caif.h>
  #include <net/rtnetlink.h>
  #include <net/caif/caif_layer.h>

  #include <net/caif/cfpkt.h>
  #include <net/caif/caif_dev.h>

  /* GPRS PDP connection has MTU to 1500 */

  #define GPRS_PDP_MTU 1500

  /* 5 sec. connect timeout */
  #define CONNECT_TIMEOUT (5 * HZ)

  #define CAIF_NET_DEFAULT_QUEUE_LEN 500

  /*This list is protected by the rtnl lock. */
  static LIST_HEAD(chnl_net_list);
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_RTNL_LINK("caif");

  enum caif_states {
  	CAIF_CONNECTED		= 1,
  	CAIF_CONNECTING,
  	CAIF_DISCONNECTED,
  	CAIF_SHUTDOWN
  };

  struct chnl_net {
  	struct cflayer chnl;
  	struct net_device_stats stats;
  	struct caif_connect_request conn_req;
  	struct list_head list_field;
  	struct net_device *netdev;
  	char name[256];
  	wait_queue_head_t netmgmt_wq;
  	/* Flow status to remember and control the transmission. */
  	bool flowenabled;

  	enum caif_states state;

  };
  
  static void robust_list_del(struct list_head *delete_node)
  {
  	struct list_head *list_node;
  	struct list_head *n;
  	ASSERT_RTNL();
  	list_for_each_safe(list_node, n, &chnl_net_list) {
  		if (list_node == delete_node) {
  			list_del(list_node);

  			return;

  		}
  	}

  	WARN_ON(1);

  }
  
  static int chnl_recv_cb(struct cflayer *layr, struct cfpkt *pkt)
  {
  	struct sk_buff *skb;

  	struct chnl_net *priv  = container_of(layr, struct chnl_net, chnl);

  	int pktlen;
  	int err = 0;

  	const u8 *ip_version;
  	u8 buf;

  
  	priv = container_of(layr, struct chnl_net, chnl);
  
  	if (!priv)
  		return -EINVAL;

  	skb = (struct sk_buff *) cfpkt_tonative(pkt);

  	/* Get length of CAIF packet. */

  	pktlen = skb->len;

  	/* Pass some minimum information and
  	 * send the packet to the net stack.
  	 */
  	skb->dev = priv->netdev;

  
  	/* check the version of IP */
  	ip_version = skb_header_pointer(skb, 0, 1, &buf);
  	if (!ip_version)
  		return -EINVAL;
  	switch (*ip_version >> 4) {
  	case 4:
  		skb->protocol = htons(ETH_P_IP);
  		break;
  	case 6:
  		skb->protocol = htons(ETH_P_IPV6);
  		break;
  	default:
  		return -EINVAL;
  	}

  
  	/* If we change the header in loop mode, the checksum is corrupted. */
  	if (priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP)
  		skb->ip_summed = CHECKSUM_UNNECESSARY;
  	else
  		skb->ip_summed = CHECKSUM_NONE;

  	if (in_interrupt())
  		netif_rx(skb);
  	else
  		netif_rx_ni(skb);
  
  	/* Update statistics. */
  	priv->netdev->stats.rx_packets++;
  	priv->netdev->stats.rx_bytes += pktlen;
  
  	return err;
  }
  
  static int delete_device(struct chnl_net *dev)
  {
  	ASSERT_RTNL();
  	if (dev->netdev)
  		unregister_netdevice(dev->netdev);
  	return 0;
  }
  
  static void close_work(struct work_struct *work)
  {
  	struct chnl_net *dev = NULL;
  	struct list_head *list_node;
  	struct list_head *_tmp;

  
  	rtnl_lock();

  	list_for_each_safe(list_node, _tmp, &chnl_net_list) {
  		dev = list_entry(list_node, struct chnl_net, list_field);

  		if (dev->state == CAIF_SHUTDOWN)
  			dev_close(dev->netdev);

  	}

  	rtnl_unlock();

  }
  static DECLARE_WORK(close_worker, close_work);

  static void chnl_hold(struct cflayer *lyr)
  {
  	struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
  	dev_hold(priv->netdev);
  }
  
  static void chnl_put(struct cflayer *lyr)
  {
  	struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
  	dev_put(priv->netdev);
  }

  static void chnl_flowctrl_cb(struct cflayer *layr, enum caif_ctrlcmd flow,
  				int phyid)
  {

  	struct chnl_net *priv = container_of(layr, struct chnl_net, chnl);

  	pr_debug("NET flowctrl func called flow: %s
  ",

  		flow == CAIF_CTRLCMD_FLOW_ON_IND ? "ON" :
  		flow == CAIF_CTRLCMD_INIT_RSP ? "INIT" :
  		flow == CAIF_CTRLCMD_FLOW_OFF_IND ? "OFF" :
  		flow == CAIF_CTRLCMD_DEINIT_RSP ? "CLOSE/DEINIT" :
  		flow == CAIF_CTRLCMD_INIT_FAIL_RSP ? "OPEN_FAIL" :
  		flow == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND ?
  		 "REMOTE_SHUTDOWN" : "UKNOWN CTRL COMMAND");

  
  	switch (flow) {
  	case CAIF_CTRLCMD_FLOW_OFF_IND:

  		priv->flowenabled = false;
  		netif_stop_queue(priv->netdev);
  		break;

  	case CAIF_CTRLCMD_DEINIT_RSP:

  		priv->state = CAIF_DISCONNECTED;
  		break;

  	case CAIF_CTRLCMD_INIT_FAIL_RSP:

  		priv->state = CAIF_DISCONNECTED;
  		wake_up_interruptible(&priv->netmgmt_wq);
  		break;

  	case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:

  		priv->state = CAIF_SHUTDOWN;

  		netif_tx_disable(priv->netdev);

  		schedule_work(&close_worker);
  		break;
  	case CAIF_CTRLCMD_FLOW_ON_IND:

  		priv->flowenabled = true;
  		netif_wake_queue(priv->netdev);
  		break;

  	case CAIF_CTRLCMD_INIT_RSP:

  		caif_client_register_refcnt(&priv->chnl, chnl_hold, chnl_put);

  		priv->state = CAIF_CONNECTED;

  		priv->flowenabled = true;
  		netif_wake_queue(priv->netdev);
  		wake_up_interruptible(&priv->netmgmt_wq);
  		break;
  	default:
  		break;
  	}
  }
  
  static int chnl_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct chnl_net *priv;
  	struct cfpkt *pkt = NULL;
  	int len;
  	int result = -1;
  	/* Get our private data. */
  	priv = netdev_priv(dev);
  
  	if (skb->len > priv->netdev->mtu) {

  		pr_warn("Size of skb exceeded MTU
  ");

  		return -ENOSPC;
  	}
  
  	if (!priv->flowenabled) {

  		pr_debug("dropping packets flow off
  ");

  		return NETDEV_TX_BUSY;
  	}
  
  	if (priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP)
  		swap(ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);
  
  	/* Store original SKB length. */
  	len = skb->len;
  
  	pkt = cfpkt_fromnative(CAIF_DIR_OUT, (void *) skb);

  	/* Send the packet down the stack. */
  	result = priv->chnl.dn->transmit(priv->chnl.dn, pkt);
  	if (result) {
  		if (result == -EAGAIN)
  			result = NETDEV_TX_BUSY;
  		return result;
  	}
  
  	/* Update statistics. */
  	dev->stats.tx_packets++;
  	dev->stats.tx_bytes += len;
  
  	return NETDEV_TX_OK;
  }
  
  static int chnl_net_open(struct net_device *dev)
  {
  	struct chnl_net *priv = NULL;
  	int result = -1;

  	int llifindex, headroom, tailroom, mtu;
  	struct net_device *lldev;

  	ASSERT_RTNL();

  	priv = netdev_priv(dev);

  	if (!priv) {

  		pr_debug("chnl_net_open: no priv
  ");

  		return -ENODEV;
  	}

  
  	if (priv->state != CAIF_CONNECTING) {
  		priv->state = CAIF_CONNECTING;

  		result = caif_connect_client(dev_net(dev), &priv->conn_req,
  						&priv->chnl, &llifindex,
  						&headroom, &tailroom);

  		if (result != 0) {

  				pr_debug("err: "
  					 "Unable to register and open device,"
  					 " Err:%d
  ",
  					 result);

  				goto error;
  		}
  
  		lldev = dev_get_by_index(dev_net(dev), llifindex);
  
  		if (lldev == NULL) {

  			pr_debug("no interface?
  ");

  			result = -ENODEV;
  			goto error;
  		}
  
  		dev->needed_tailroom = tailroom + lldev->needed_tailroom;
  		dev->hard_header_len = headroom + lldev->hard_header_len +
  			lldev->needed_tailroom;
  
  		/*
  		 * MTU, head-room etc is not know before we have a
  		 * CAIF link layer device available. MTU calculation may
  		 * override initial RTNL configuration.
  		 * MTU is minimum of current mtu, link layer mtu pluss
  		 * CAIF head and tail, and PDP GPRS contexts max MTU.
  		 */
  		mtu = min_t(int, dev->mtu, lldev->mtu - (headroom + tailroom));
  		mtu = min_t(int, GPRS_PDP_MTU, mtu);
  		dev_set_mtu(dev, mtu);
  		dev_put(lldev);
  
  		if (mtu < 100) {

  			pr_warn("CAIF Interface MTU too small (%d)
  ", mtu);

  			result = -ENODEV;
  			goto error;

  		}

  	}

  	rtnl_unlock();  /* Release RTNL lock during connect wait */

  	result = wait_event_interruptible_timeout(priv->netmgmt_wq,
  						priv->state != CAIF_CONNECTING,
  						CONNECT_TIMEOUT);

  	rtnl_lock();

  	if (result == -ERESTARTSYS) {

  		pr_debug("wait_event_interruptible woken by a signal
  ");

  		result = -ERESTARTSYS;
  		goto error;

  	}

  	if (result == 0) {

  		pr_debug("connect timeout
  ");

  		caif_disconnect_client(dev_net(dev), &priv->chnl);

  		priv->state = CAIF_DISCONNECTED;

  		pr_debug("state disconnected
  ");

  		result = -ETIMEDOUT;
  		goto error;

  	}

  	if (priv->state != CAIF_CONNECTED) {

  		pr_debug("connect failed
  ");

  		result = -ECONNREFUSED;
  		goto error;

  	}

  	pr_debug("CAIF Netdevice connected
  ");

  	return 0;

  
  error:

  	caif_disconnect_client(dev_net(dev), &priv->chnl);

  	priv->state = CAIF_DISCONNECTED;

  	pr_debug("state disconnected
  ");

  	return result;

  }
  
  static int chnl_net_stop(struct net_device *dev)
  {
  	struct chnl_net *priv;

  	ASSERT_RTNL();
  	priv = netdev_priv(dev);

  	priv->state = CAIF_DISCONNECTED;

  	caif_disconnect_client(dev_net(dev), &priv->chnl);

  	return 0;
  }
  
  static int chnl_net_init(struct net_device *dev)
  {
  	struct chnl_net *priv;
  	ASSERT_RTNL();
  	priv = netdev_priv(dev);
  	strncpy(priv->name, dev->name, sizeof(priv->name));
  	return 0;
  }
  
  static void chnl_net_uninit(struct net_device *dev)
  {
  	struct chnl_net *priv;
  	ASSERT_RTNL();
  	priv = netdev_priv(dev);
  	robust_list_del(&priv->list_field);
  }
  
  static const struct net_device_ops netdev_ops = {
  	.ndo_open = chnl_net_open,
  	.ndo_stop = chnl_net_stop,
  	.ndo_init = chnl_net_init,
  	.ndo_uninit = chnl_net_uninit,
  	.ndo_start_xmit = chnl_net_start_xmit,
  };

  static void chnl_net_destructor(struct net_device *dev)
  {
  	struct chnl_net *priv = netdev_priv(dev);
  	caif_free_client(&priv->chnl);
  	free_netdev(dev);
  }

  static void ipcaif_net_setup(struct net_device *dev)
  {
  	struct chnl_net *priv;
  	dev->netdev_ops = &netdev_ops;

  	dev->destructor = chnl_net_destructor;

  	dev->flags |= IFF_NOARP;
  	dev->flags |= IFF_POINTOPOINT;

  	dev->mtu = GPRS_PDP_MTU;

  	dev->tx_queue_len = CAIF_NET_DEFAULT_QUEUE_LEN;
  
  	priv = netdev_priv(dev);
  	priv->chnl.receive = chnl_recv_cb;
  	priv->chnl.ctrlcmd = chnl_flowctrl_cb;
  	priv->netdev = dev;
  	priv->conn_req.protocol = CAIFPROTO_DATAGRAM;
  	priv->conn_req.link_selector = CAIF_LINK_HIGH_BANDW;
  	priv->conn_req.priority = CAIF_PRIO_LOW;
  	/* Insert illegal value */

  	priv->conn_req.sockaddr.u.dgm.connection_id = 0;

  	priv->flowenabled = false;

  	init_waitqueue_head(&priv->netmgmt_wq);

  }
  
  
  static int ipcaif_fill_info(struct sk_buff *skb, const struct net_device *dev)
  {
  	struct chnl_net *priv;
  	u8 loop;
  	priv = netdev_priv(dev);
  	NLA_PUT_U32(skb, IFLA_CAIF_IPV4_CONNID,
  		    priv->conn_req.sockaddr.u.dgm.connection_id);
  	NLA_PUT_U32(skb, IFLA_CAIF_IPV6_CONNID,
  		    priv->conn_req.sockaddr.u.dgm.connection_id);
  	loop = priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP;
  	NLA_PUT_U8(skb, IFLA_CAIF_LOOPBACK, loop);
  
  
  	return 0;
  nla_put_failure:
  	return -EMSGSIZE;
  
  }
  
  static void caif_netlink_parms(struct nlattr *data[],
  				struct caif_connect_request *conn_req)
  {
  	if (!data) {

  		pr_warn("no params data found
  ");

  		return;
  	}
  	if (data[IFLA_CAIF_IPV4_CONNID])
  		conn_req->sockaddr.u.dgm.connection_id =
  			nla_get_u32(data[IFLA_CAIF_IPV4_CONNID]);
  	if (data[IFLA_CAIF_IPV6_CONNID])
  		conn_req->sockaddr.u.dgm.connection_id =
  			nla_get_u32(data[IFLA_CAIF_IPV6_CONNID]);
  	if (data[IFLA_CAIF_LOOPBACK]) {
  		if (nla_get_u8(data[IFLA_CAIF_LOOPBACK]))
  			conn_req->protocol = CAIFPROTO_DATAGRAM_LOOP;
  		else
  			conn_req->protocol = CAIFPROTO_DATAGRAM;
  	}
  }
  
  static int ipcaif_newlink(struct net *src_net, struct net_device *dev,
  			  struct nlattr *tb[], struct nlattr *data[])
  {
  	int ret;
  	struct chnl_net *caifdev;
  	ASSERT_RTNL();
  	caifdev = netdev_priv(dev);
  	caif_netlink_parms(data, &caifdev->conn_req);

  	dev_net_set(caifdev->netdev, src_net);

  	ret = register_netdevice(dev);
  	if (ret)

  		pr_warn("device rtml registration failed
  ");

  	else
  		list_add(&caifdev->list_field, &chnl_net_list);

  
  	/* Take ifindex as connection-id if null */
  	if (caifdev->conn_req.sockaddr.u.dgm.connection_id == 0)
  		caifdev->conn_req.sockaddr.u.dgm.connection_id = dev->ifindex;

  	return ret;
  }
  
  static int ipcaif_changelink(struct net_device *dev, struct nlattr *tb[],
  				struct nlattr *data[])
  {
  	struct chnl_net *caifdev;
  	ASSERT_RTNL();
  	caifdev = netdev_priv(dev);
  	caif_netlink_parms(data, &caifdev->conn_req);
  	netdev_state_change(dev);
  	return 0;
  }
  
  static size_t ipcaif_get_size(const struct net_device *dev)
  {
  	return
  		/* IFLA_CAIF_IPV4_CONNID */
  		nla_total_size(4) +
  		/* IFLA_CAIF_IPV6_CONNID */
  		nla_total_size(4) +
  		/* IFLA_CAIF_LOOPBACK */
  		nla_total_size(2) +
  		0;
  }
  
  static const struct nla_policy ipcaif_policy[IFLA_CAIF_MAX + 1] = {
  	[IFLA_CAIF_IPV4_CONNID]	      = { .type = NLA_U32 },
  	[IFLA_CAIF_IPV6_CONNID]	      = { .type = NLA_U32 },
  	[IFLA_CAIF_LOOPBACK]	      = { .type = NLA_U8 }
  };
  
  
  static struct rtnl_link_ops ipcaif_link_ops __read_mostly = {
  	.kind		= "caif",
  	.priv_size	= sizeof(struct chnl_net),
  	.setup		= ipcaif_net_setup,
  	.maxtype	= IFLA_CAIF_MAX,
  	.policy		= ipcaif_policy,
  	.newlink	= ipcaif_newlink,
  	.changelink	= ipcaif_changelink,
  	.get_size	= ipcaif_get_size,
  	.fill_info	= ipcaif_fill_info,
  
  };
  
  static int __init chnl_init_module(void)
  {
  	return rtnl_link_register(&ipcaif_link_ops);
  }
  
  static void __exit chnl_exit_module(void)
  {
  	struct chnl_net *dev = NULL;
  	struct list_head *list_node;
  	struct list_head *_tmp;
  	rtnl_link_unregister(&ipcaif_link_ops);
  	rtnl_lock();
  	list_for_each_safe(list_node, _tmp, &chnl_net_list) {
  		dev = list_entry(list_node, struct chnl_net, list_field);
  		list_del(list_node);
  		delete_device(dev);
  	}
  	rtnl_unlock();
  }
  
  module_init(chnl_init_module);
  module_exit(chnl_exit_module);