/* Copyright (c) 2013-2017, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only 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.
 *
 *
 * RMNET Data virtual network driver
 *
 */

#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <net/pkt_sched.h>
#include "rmnet_config.h"
#include "rmnet_handlers.h"
#include "rmnet_private.h"
#include "rmnet_map.h"
#include "rmnet_vnd.h"

/* RX/TX Fixup */

void rmnet_vnd_rx_fixup(struct sk_buff *skb, struct net_device *dev)
{
	dev->stats.rx_packets++;
	dev->stats.rx_bytes += skb->len;
}

void rmnet_vnd_tx_fixup(struct sk_buff *skb, struct net_device *dev)
{
	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;
}

/* Network Device Operations */

static netdev_tx_t rmnet_vnd_start_xmit(struct sk_buff *skb,
					struct net_device *dev)
{
	struct rmnet_priv *priv;

	priv = netdev_priv(dev);
	if (priv->local_ep.egress_dev) {
		rmnet_egress_handler(skb, &priv->local_ep);
	} else {
		dev->stats.tx_dropped++;
		kfree_skb(skb);
	}
	return NETDEV_TX_OK;
}

static int rmnet_vnd_change_mtu(struct net_device *rmnet_dev, int new_mtu)
{
	if (new_mtu < 0 || new_mtu > RMNET_MAX_PACKET_SIZE)
		return -EINVAL;

	rmnet_dev->mtu = new_mtu;
	return 0;
}

static int rmnet_vnd_get_iflink(const struct net_device *dev)
{
	struct rmnet_priv *priv = netdev_priv(dev);

	return priv->real_dev->ifindex;
}

static const struct net_device_ops rmnet_vnd_ops = {
	.ndo_start_xmit = rmnet_vnd_start_xmit,
	.ndo_change_mtu = rmnet_vnd_change_mtu,
	.ndo_get_iflink = rmnet_vnd_get_iflink,
};

/* Called by kernel whenever a new rmnet<n> device is created. Sets MTU,
 * flags, ARP type, needed headroom, etc...
 */
void rmnet_vnd_setup(struct net_device *rmnet_dev)
{
	rmnet_dev->netdev_ops = &rmnet_vnd_ops;
	rmnet_dev->mtu = RMNET_DFLT_PACKET_SIZE;
	rmnet_dev->needed_headroom = RMNET_NEEDED_HEADROOM;
	random_ether_addr(rmnet_dev->dev_addr);
	rmnet_dev->tx_queue_len = RMNET_TX_QUEUE_LEN;

	/* Raw IP mode */
	rmnet_dev->header_ops = NULL;  /* No header */
	rmnet_dev->type = ARPHRD_RAWIP;
	rmnet_dev->hard_header_len = 0;
	rmnet_dev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);

	rmnet_dev->needs_free_netdev = true;
}

/* Exposed API */

int rmnet_vnd_newlink(u8 id, struct net_device *rmnet_dev,
		      struct rmnet_port *port,
		      struct net_device *real_dev)
{
	struct rmnet_priv *priv;
	int rc;

	if (port->rmnet_devices[id])
		return -EINVAL;

	rc = register_netdevice(rmnet_dev);
	if (!rc) {
		port->rmnet_devices[id] = rmnet_dev;
		port->nr_rmnet_devs++;

		rmnet_dev->rtnl_link_ops = &rmnet_link_ops;

		priv = netdev_priv(rmnet_dev);
		priv->mux_id = id;
		priv->real_dev = real_dev;

		netdev_dbg(rmnet_dev, "rmnet dev created\n");
	}

	return rc;
}

int rmnet_vnd_dellink(u8 id, struct rmnet_port *port)
{
	if (id >= RMNET_MAX_LOGICAL_EP || !port->rmnet_devices[id])
		return -EINVAL;

	port->rmnet_devices[id] = NULL;
	port->nr_rmnet_devs--;
	return 0;
}

u8 rmnet_vnd_get_mux(struct net_device *rmnet_dev)
{
	struct rmnet_priv *priv;

	priv = netdev_priv(rmnet_dev);
	return priv->mux_id;
}

/* Gets the logical endpoint configuration for a RmNet virtual network device
 * node. Caller should confirm that devices is a RmNet VND before calling.
 */
struct rmnet_endpoint *rmnet_vnd_get_endpoint(struct net_device *rmnet_dev)
{
	struct rmnet_priv *priv;

	if (!rmnet_dev)
		return NULL;

	priv = netdev_priv(rmnet_dev);

	return &priv->local_ep;
}

int rmnet_vnd_do_flow_control(struct net_device *rmnet_dev, int enable)
{
	netdev_dbg(rmnet_dev, "Setting VND TX queue state to %d\n", enable);
	/* Although we expect similar number of enable/disable
	 * commands, optimize for the disable. That is more
	 * latency sensitive than enable
	 */
	if (unlikely(enable))
		netif_wake_queue(rmnet_dev);
	else
		netif_stop_queue(rmnet_dev);

	return 0;
}