/*
 * This file contains the handling of RX in wlan driver.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/etherdevice.h>
#include <linux/hardirq.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/export.h>
#include <net/cfg80211.h>

#include "defs.h"
#include "host.h"
#include "radiotap.h"
#include "decl.h"
#include "dev.h"
#include "mesh.h"

struct eth803hdr {
        u8 dest_addr[6];
        u8 src_addr[6];
        u16 h803_len;
} __packed;

struct rfc1042hdr {
        u8 llc_dsap;
        u8 llc_ssap;
        u8 llc_ctrl;
        u8 snap_oui[3];
        u16 snap_type;
} __packed;

struct rxpackethdr {
        struct eth803hdr eth803_hdr;
        struct rfc1042hdr rfc1042_hdr;
} __packed;

struct rx80211packethdr {
        struct rxpd rx_pd;
        void *eth80211_hdr;
} __packed;

static int process_rxed_802_11_packet(struct lbs_private *priv,
        struct sk_buff *skb);

/**
 * lbs_process_rxed_packet - processes received packet and forwards it
 * to kernel/upper layer
 *
 * @priv:       A pointer to &struct lbs_private
 * @skb:        A pointer to skb which includes the received packet
 * returns:     0 or -1
 */
int lbs_process_rxed_packet(struct lbs_private *priv, struct sk_buff *skb)
{
        int ret = 0;
        struct net_device *dev = priv->dev;
        struct rxpackethdr *p_rx_pkt;
        struct rxpd *p_rx_pd;
        int hdrchop;
        struct ethhdr *p_ethhdr;
        static const u8 rfc1042_eth_hdr[] = {
                0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00
        };

        lbs_deb_enter(LBS_DEB_RX);

        BUG_ON(!skb);

        skb->ip_summed = CHECKSUM_NONE;

        if (priv->wdev->iftype == NL80211_IFTYPE_MONITOR)
                return process_rxed_802_11_packet(priv, skb);

        p_rx_pd = (struct rxpd *) skb->data;
        p_rx_pkt = (struct rxpackethdr *) ((u8 *)p_rx_pd +
                le32_to_cpu(p_rx_pd->pkt_ptr));

        dev = lbs_mesh_set_dev(priv, dev, p_rx_pd);

        lbs_deb_hex(LBS_DEB_RX, "RX Data: Before chop rxpd", skb->data,
                 min_t(unsigned int, skb->len, 100));

        if (skb->len < (ETH_HLEN + 8 + sizeof(struct rxpd))) {
                lbs_deb_rx("rx err: frame received with bad length\n");
                dev->stats.rx_length_errors++;
                ret = 0;
                dev_kfree_skb(skb);
                goto done;
        }

        lbs_deb_rx("rx data: skb->len - pkt_ptr = %d-%zd = %zd\n",
                skb->len, (size_t)le32_to_cpu(p_rx_pd->pkt_ptr),
                skb->len - (size_t)le32_to_cpu(p_rx_pd->pkt_ptr));

        lbs_deb_hex(LBS_DEB_RX, "RX Data: Dest", p_rx_pkt->eth803_hdr.dest_addr,
                sizeof(p_rx_pkt->eth803_hdr.dest_addr));
        lbs_deb_hex(LBS_DEB_RX, "RX Data: Src", p_rx_pkt->eth803_hdr.src_addr,
                sizeof(p_rx_pkt->eth803_hdr.src_addr));

        if (memcmp(&p_rx_pkt->rfc1042_hdr,
                   rfc1042_eth_hdr, sizeof(rfc1042_eth_hdr)) == 0) {
                /*
                 *  Replace the 803 header and rfc1042 header (llc/snap) with an
                 *    EthernetII header, keep the src/dst and snap_type (ethertype)
                 *
                 *  The firmware only passes up SNAP frames converting
                 *    all RX Data from 802.11 to 802.2/LLC/SNAP frames.
                 *
                 *  To create the Ethernet II, just move the src, dst address right
                 *    before the snap_type.
                 */
                p_ethhdr = (struct ethhdr *)
                    ((u8 *) &p_rx_pkt->eth803_hdr
                     + sizeof(p_rx_pkt->eth803_hdr) + sizeof(p_rx_pkt->rfc1042_hdr)
                     - sizeof(p_rx_pkt->eth803_hdr.dest_addr)
                     - sizeof(p_rx_pkt->eth803_hdr.src_addr)
                     - sizeof(p_rx_pkt->rfc1042_hdr.snap_type));

                memcpy(p_ethhdr->h_source, p_rx_pkt->eth803_hdr.src_addr,
                       sizeof(p_ethhdr->h_source));
                memcpy(p_ethhdr->h_dest, p_rx_pkt->eth803_hdr.dest_addr,
                       sizeof(p_ethhdr->h_dest));

                /* Chop off the rxpd + the excess memory from the 802.2/llc/snap header
                 *   that was removed
                 */
                hdrchop = (u8 *)p_ethhdr - (u8 *)p_rx_pd;
        } else {
                lbs_deb_hex(LBS_DEB_RX, "RX Data: LLC/SNAP",
                        (u8 *) &p_rx_pkt->rfc1042_hdr,
                        sizeof(p_rx_pkt->rfc1042_hdr));

                /* Chop off the rxpd */
                hdrchop = (u8 *)&p_rx_pkt->eth803_hdr - (u8 *)p_rx_pd;
        }

        /* Chop off the leading header bytes so the skb points to the start of
         *   either the reconstructed EthII frame or the 802.2/llc/snap frame
         */
        skb_pull(skb, hdrchop);

        priv->cur_rate = lbs_fw_index_to_data_rate(p_rx_pd->rx_rate);

        lbs_deb_rx("rx data: size of actual packet %d\n", skb->len);
        dev->stats.rx_bytes += skb->len;
        dev->stats.rx_packets++;

        skb->protocol = eth_type_trans(skb, dev);
        if (in_interrupt())
                netif_rx(skb);
        else
                netif_rx_ni(skb);

        ret = 0;
done:
        lbs_deb_leave_args(LBS_DEB_RX, "ret %d", ret);
        return ret;
}
EXPORT_SYMBOL_GPL(lbs_process_rxed_packet);

/**
 * convert_mv_rate_to_radiotap - converts Tx/Rx rates from Marvell WLAN format
 * (see Table 2 in Section 3.1) to IEEE80211_RADIOTAP_RATE units (500 Kb/s)
 *
 * @rate:       Input rate
 * returns:     Output Rate (0 if invalid)
 */
static u8 convert_mv_rate_to_radiotap(u8 rate)
{
        switch (rate) {
        case 0:         /*   1 Mbps */
                return 2;
        case 1:         /*   2 Mbps */
                return 4;
        case 2:         /* 5.5 Mbps */
                return 11;
        case 3:         /*  11 Mbps */
                return 22;
        /* case 4: reserved */
        case 5:         /*   6 Mbps */
                return 12;
        case 6:         /*   9 Mbps */
                return 18;
        case 7:         /*  12 Mbps */
                return 24;
        case 8:         /*  18 Mbps */
                return 36;
        case 9:         /*  24 Mbps */
                return 48;
        case 10:                /*  36 Mbps */
                return 72;
        case 11:                /*  48 Mbps */
                return 96;
        case 12:                /*  54 Mbps */
                return 108;
        }
        pr_alert("Invalid Marvell WLAN rate %i\n", rate);
        return 0;
}

/**
 * process_rxed_802_11_packet - processes a received 802.11 packet and forwards
 * it to kernel/upper layer
 *
 * @priv:       A pointer to &struct lbs_private
 * @skb:        A pointer to skb which includes the received packet
 * returns:     0 or -1
 */
static int process_rxed_802_11_packet(struct lbs_private *priv,
        struct sk_buff *skb)
{
        int ret = 0;
        struct net_device *dev = priv->dev;
        struct rx80211packethdr *p_rx_pkt;
        struct rxpd *prxpd;
        struct rx_radiotap_hdr radiotap_hdr;
        struct rx_radiotap_hdr *pradiotap_hdr;

        lbs_deb_enter(LBS_DEB_RX);

        p_rx_pkt = (struct rx80211packethdr *) skb->data;
        prxpd = &p_rx_pkt->rx_pd;

        /* lbs_deb_hex(LBS_DEB_RX, "RX Data: Before chop rxpd", skb->data, min(skb->len, 100)); */

        if (skb->len < (ETH_HLEN + 8 + sizeof(struct rxpd))) {
                lbs_deb_rx("rx err: frame received with bad length\n");
                dev->stats.rx_length_errors++;
                ret = -EINVAL;
                kfree_skb(skb);
                goto done;
        }

        lbs_deb_rx("rx data: skb->len-sizeof(RxPd) = %d-%zd = %zd\n",
               skb->len, sizeof(struct rxpd), skb->len - sizeof(struct rxpd));

        /* create the exported radio header */

        /* radiotap header */
        memset(&radiotap_hdr, 0, sizeof(radiotap_hdr));
        /* XXX must check radiotap_hdr.hdr.it_pad for pad */
        radiotap_hdr.hdr.it_len = cpu_to_le16 (sizeof(struct rx_radiotap_hdr));
        radiotap_hdr.hdr.it_present = cpu_to_le32 (RX_RADIOTAP_PRESENT);
        radiotap_hdr.rate = convert_mv_rate_to_radiotap(prxpd->rx_rate);
        /* XXX must check no carryout */
        radiotap_hdr.antsignal = prxpd->snr + prxpd->nf;

        /* chop the rxpd */
        skb_pull(skb, sizeof(struct rxpd));

        /* add space for the new radio header */
        if ((skb_headroom(skb) < sizeof(struct rx_radiotap_hdr)) &&
            pskb_expand_head(skb, sizeof(struct rx_radiotap_hdr), 0, GFP_ATOMIC)) {
                netdev_alert(dev, "%s: couldn't pskb_expand_head\n", __func__);
                ret = -ENOMEM;
                kfree_skb(skb);
                goto done;
        }

        pradiotap_hdr = (void *)skb_push(skb, sizeof(struct rx_radiotap_hdr));
        memcpy(pradiotap_hdr, &radiotap_hdr, sizeof(struct rx_radiotap_hdr));

        priv->cur_rate = lbs_fw_index_to_data_rate(prxpd->rx_rate);

        lbs_deb_rx("rx data: size of actual packet %d\n", skb->len);
        dev->stats.rx_bytes += skb->len;
        dev->stats.rx_packets++;

        skb->protocol = eth_type_trans(skb, priv->dev);

        if (in_interrupt())
                netif_rx(skb);
        else
                netif_rx_ni(skb);

        ret = 0;

done:
        lbs_deb_leave_args(LBS_DEB_RX, "ret %d", ret);
        return ret;
}