/*
 * Copyright (C) 2016 Spreadtrum Communications Inc.
 *
 * Authors	:
 * star.liu <star.liu@spreadtrum.com>
 * yifei.li <yifei.li@spreadtrum.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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 "defrag.h"
#include "rx_msg.h"

static struct rx_defrag_node
*find_defrag_node(struct sprdwl_rx_defrag_entry *defrag_entry,
		  struct rx_msdu_desc *msdu_desc)
{
	struct rx_defrag_node *node = NULL, *pos_node = NULL;

	list_for_each_entry(pos_node, &defrag_entry->list, list) {
		if ((pos_node->desc.sta_lut_index ==
			 msdu_desc->sta_lut_index) &&
			(pos_node->desc.tid == msdu_desc->tid)) {
			if ((pos_node->desc.seq_num == msdu_desc->seq_num) &&
				((pos_node->last_frag_num + 1) ==
				 msdu_desc->frag_num)) {
				/* Node alive & fragment avail */
				pos_node->last_frag_num = msdu_desc->frag_num;
				wl_debug("%s: last_frag_num: %d\n",
					 __func__, pos_node->last_frag_num);
				node = pos_node;
			}
			break;
		}
	}

	return node;
}

static inline void __init_first_frag_node(struct rx_defrag_node *node,
					  struct rx_msdu_desc *msdu_desc)
{
	node->desc.sta_lut_index = msdu_desc->sta_lut_index;
	node->desc.tid = msdu_desc->tid;
	node->desc.frag_num = msdu_desc->frag_num;
	node->desc.seq_num = msdu_desc->seq_num;

	if (!skb_queue_empty(&node->skb_list))
		skb_queue_purge(&node->skb_list);

	if (likely(msdu_desc->snap_hdr_present))
		node->msdu_len = ETH_HLEN + msdu_desc->msdu_offset;
	else
		node->msdu_len = 2*ETH_ALEN + msdu_desc->msdu_offset;

	node->last_frag_num = msdu_desc->frag_num;
}

static struct rx_defrag_node
*init_first_defrag_node(struct sprdwl_rx_defrag_entry *defrag_entry,
			  struct rx_msdu_desc *msdu_desc)
{
	struct rx_defrag_node *node = NULL, *pos_node = NULL;
	bool ret = true;

	/* Check whether this entry alive or this fragment avail */
	list_for_each_entry(pos_node, &defrag_entry->list, list) {
		if ((pos_node->desc.sta_lut_index ==
			 msdu_desc->sta_lut_index) &&
			(pos_node->desc.tid == msdu_desc->tid)) {
			if (!seqno_leq(msdu_desc->seq_num,
					   pos_node->desc.seq_num)) {
				/* Replace this entry */
				wl_err("%s: fragment replace: %d, %d\n",
					   __func__, msdu_desc->seq_num,
					   pos_node->desc.seq_num);
				node = pos_node;
			} else {
				/* fragment not avail */
				wl_err("%s: fragment not avail: %d, %d\n",
					   __func__, msdu_desc->seq_num,
					   pos_node->desc.seq_num);
				ret = false;
			}
			break;
		}
	}

	if (ret) {
		if (!node) {
			/* Get the empty or oldest entry
			 * HW just maintain three fragLUTs
			 * just kick out oldest entry (Should it happen?)
			 */
			node = list_entry(defrag_entry->list.prev,
					  struct rx_defrag_node, list);
		}
		__init_first_frag_node(node, msdu_desc);

		/* Move this node to head */
		if (defrag_entry->list.next != &node->list)
			list_move(&node->list, &defrag_entry->list);
	}

	return node;
}

static struct rx_defrag_node
*get_defrag_node(struct sprdwl_rx_defrag_entry *defrag_entry,
		 struct rx_msdu_desc *msdu_desc)
{
	struct rx_defrag_node *node = NULL;

	wl_debug("%s: frag_num: %d\n", __func__, msdu_desc->frag_num);

	/* HW do not record entry time when HW suspend
	 * So we need to judge whether this entry is alive
	 */
	if (msdu_desc->frag_num) {
		/* Check whether this entry alive or this fragment avail */
		node = find_defrag_node(defrag_entry, msdu_desc);
	} else {
		node = init_first_defrag_node(defrag_entry, msdu_desc);
	}

	return node;
}

static struct sk_buff
*defrag_single_data_process(struct sprdwl_rx_defrag_entry *defrag_entry,
				struct sk_buff *pskb)
{
	struct rx_defrag_node *node = NULL;
	struct rx_msdu_desc *msdu_desc = (struct rx_msdu_desc *)pskb->data;
	unsigned short offset = 0, frag_len = 0, frag_offset = 0;
	struct sk_buff *skb = NULL, *pos_skb = NULL;

	node = get_defrag_node(defrag_entry, msdu_desc);
	if (node) {
		skb_queue_tail(&node->skb_list, pskb);
		if (msdu_desc->snap_hdr_present)
			frag_len = msdu_desc->msdu_len - ETH_HLEN;
		else
			frag_len = msdu_desc->msdu_len - 2*ETH_ALEN;
		node->msdu_len += frag_len;

		wl_debug("%s: more_frag_bit: %d, node msdu_len: %d\n",
			 __func__, msdu_desc->more_frag_bit, node->msdu_len);
		if (!msdu_desc->more_frag_bit) {
			skb = skb_dequeue(&node->skb_list);
			msdu_desc = (struct rx_msdu_desc *)skb->data;
			offset = msdu_total_len(msdu_desc);
			msdu_desc->msdu_len =
				node->msdu_len - msdu_desc->msdu_offset;

			pos_skb = dev_alloc_skb(node->msdu_len);
			if (unlikely(!pos_skb)) {
				/* Free all skbs */
				wl_err("%s: expand skb fail\n", __func__);
				skb_queue_purge(&node->skb_list);
				dev_kfree_skb(skb);
				skb = NULL;
				goto exit;
			}

			memcpy(pos_skb->data, skb->data, offset);
			dev_kfree_skb(skb);
			skb = pos_skb;

			while ((pos_skb = skb_dequeue(&node->skb_list))) {
				msdu_desc =
					(struct rx_msdu_desc *)pos_skb->data;
				if (msdu_desc->snap_hdr_present) {
					frag_len = msdu_desc->msdu_len -
							ETH_HLEN;
					frag_offset = msdu_desc->msdu_offset +
							ETH_HLEN;
				} else {
					frag_len = msdu_desc->msdu_len -
							2*ETH_ALEN;
					frag_offset = msdu_desc->msdu_offset +
							2*ETH_ALEN;
				}

				wl_debug("%s: frag_len: %d, frag_offset: %d\n",
					 __func__, frag_len, frag_offset);
				memcpy((skb->data + offset),
					   (pos_skb->data + frag_offset), frag_len);
				offset += frag_len;

				dev_kfree_skb(pos_skb);
			}

			fill_skb_csum(skb, 0);
			skb->next = NULL;
exit:
			/* Move this entry to tail */
			if (!list_is_last(&node->list, &defrag_entry->list))
				list_move_tail(&node->list,
						   &defrag_entry->list);
		}
	} else {
		dev_kfree_skb(pskb);
	}

	return skb;
}

struct sk_buff
*defrag_data_process(struct sprdwl_rx_defrag_entry *defrag_entry,
			 struct sk_buff *pskb)
{
	struct rx_msdu_desc *msdu_desc = (struct rx_msdu_desc *)pskb->data;
	struct sk_buff *skb = NULL;

	if (!msdu_desc->frag_num && !msdu_desc->more_frag_bit)
		skb = pskb;
	else
		skb = defrag_single_data_process(defrag_entry, pskb);

	return skb;
}

int sprdwl_defrag_init(struct sprdwl_rx_defrag_entry *defrag_entry)
{
	int i = 0;
	struct rx_defrag_node *node = NULL;
	int ret = 0;

	INIT_LIST_HEAD(&defrag_entry->list);

	for (i = 0; i < MAX_DEFRAG_NUM; i++) {
		node = kzalloc(sizeof(*node), GFP_KERNEL);
		if (likely(node)) {
			skb_queue_head_init(&node->skb_list);
			list_add(&node->list, &defrag_entry->list);
		} else {
			wl_err("%s: fail to alloc rx_defrag_node\n", __func__);
			ret = -ENOMEM;
			break;
		}
	}

	return ret;
}

void sprdwl_defrag_deinit(struct sprdwl_rx_defrag_entry *defrag_entry)
{
	struct rx_defrag_node *node = NULL, *pos_node = NULL;

	list_for_each_entry_safe(node, pos_node, &defrag_entry->list, list) {
		list_del(&node->list);
		if (!skb_queue_empty(&node->skb_list))
			skb_queue_purge(&node->skb_list);
		kfree(node);
	}
}