/*
   * Copyright (c) 2015, 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.
   */
  
  #include <linux/etherdevice.h>

  #include "dsa_priv.h"
  
  #define QCA_HDR_LEN	2
  #define QCA_HDR_VERSION	0x2
  
  #define QCA_HDR_RECV_VERSION_MASK	GENMASK(15, 14)
  #define QCA_HDR_RECV_VERSION_S		14
  #define QCA_HDR_RECV_PRIORITY_MASK	GENMASK(13, 11)
  #define QCA_HDR_RECV_PRIORITY_S		11
  #define QCA_HDR_RECV_TYPE_MASK		GENMASK(10, 6)
  #define QCA_HDR_RECV_TYPE_S		6
  #define QCA_HDR_RECV_FRAME_IS_TAGGED	BIT(3)
  #define QCA_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
  
  #define QCA_HDR_XMIT_VERSION_MASK	GENMASK(15, 14)
  #define QCA_HDR_XMIT_VERSION_S		14
  #define QCA_HDR_XMIT_PRIORITY_MASK	GENMASK(13, 11)
  #define QCA_HDR_XMIT_PRIORITY_S		11
  #define QCA_HDR_XMIT_CONTROL_MASK	GENMASK(10, 8)
  #define QCA_HDR_XMIT_CONTROL_S		8
  #define QCA_HDR_XMIT_FROM_CPU		BIT(7)
  #define QCA_HDR_XMIT_DP_BIT_MASK	GENMASK(6, 0)
  
  static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct dsa_slave_priv *p = netdev_priv(dev);
  	u16 *phdr, hdr;
  
  	dev->stats.tx_packets++;
  	dev->stats.tx_bytes += skb->len;
  
  	if (skb_cow_head(skb, 0) < 0)

  		return NULL;

  
  	skb_push(skb, QCA_HDR_LEN);
  
  	memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
  	phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
  
  	/* Set the version field, and set destination port information */
  	hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
  		QCA_HDR_XMIT_FROM_CPU |

  		BIT(p->dp->index);

  
  	*phdr = htons(hdr);
  
  	return skb;

  }

  static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,

  				   struct packet_type *pt)

  {
  	struct dsa_switch_tree *dst = dev->dsa_ptr;

  	struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);

  	struct dsa_switch *ds;
  	u8 ver;
  	int port;
  	__be16 *phdr, hdr;

  	if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))

  		return NULL;

  
  	/* The QCA header is added by the switch between src addr and Ethertype
  	 * At this point, skb->data points to ethertype so header should be
  	 * right before
  	 */
  	phdr = (__be16 *)(skb->data - 2);
  	hdr = ntohs(*phdr);
  
  	/* Make sure the version is correct */
  	ver = (hdr & QCA_HDR_RECV_VERSION_MASK) >> QCA_HDR_RECV_VERSION_S;
  	if (unlikely(ver != QCA_HDR_VERSION))

  		return NULL;

  
  	/* Remove QCA tag and recalculate checksum */
  	skb_pull_rcsum(skb, QCA_HDR_LEN);
  	memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
  		ETH_HLEN - QCA_HDR_LEN);
  
  	/* This protocol doesn't support cascading multiple switches so it's
  	 * safe to assume the switch is first in the tree
  	 */

  	ds = cpu_dp->ds;

  	if (!ds)

  		return NULL;

  
  	/* Get source port information */
  	port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
  	if (!ds->ports[port].netdev)

  		return NULL;

  	if (unlikely(ds->cpu_port_mask & BIT(port)))
  		return NULL;

  	/* Update skb & forward the frame accordingly */

  	skb->dev = ds->ports[port].netdev;

  	return skb;

  }
  
  const struct dsa_device_ops qca_netdev_ops = {
  	.xmit	= qca_tag_xmit,
  	.rcv	= qca_tag_rcv,
  };