rx.c

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/*
 * 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);

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);

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;
}

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;
}