caif_usb.c

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/*
 * CAIF USB handler
 * Copyright (C) ST-Ericsson AB 2011
 * Author:  Sjur Brendeland/[email protected]
 * License terms: GNU General Public License (GPL) version 2
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/usbnet.h>
#include <net/netns/generic.h>
#include <net/caif/caif_dev.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/cfcnfg.h>

MODULE_LICENSE("GPL");

#define CFUSB_PAD_DESCR_SZ 1    /* Alignment descriptor length */
#define CFUSB_ALIGNMENT 4   /* Number of bytes to align. */
#define CFUSB_MAX_HEADLEN (CFUSB_PAD_DESCR_SZ + CFUSB_ALIGNMENT-1)
#define STE_USB_VID 0x04cc  /* USB Product ID for ST-Ericsson */
#define STE_USB_PID_CAIF 0x230f /* Product id for CAIF Modems */

struct cfusbl {
    struct cflayer layer;
    u8 tx_eth_hdr[ETH_HLEN];
};

static bool pack_added;

static int cfusbl_receive(struct cflayer *layr, struct cfpkt *pkt)
{
    u8 hpad;

    /* Remove padding. */
    cfpkt_extr_head(pkt, &hpad, 1);
    cfpkt_extr_head(pkt, NULL, hpad);
    return layr->up->receive(layr->up, pkt);
}

static int cfusbl_transmit(struct cflayer *layr, struct cfpkt *pkt)
{
    struct caif_payload_info *info;
    u8 hpad;
    u8 zeros[CFUSB_ALIGNMENT];
    struct sk_buff *skb;
    struct cfusbl *usbl = container_of(layr, struct cfusbl, layer);

    skb = cfpkt_tonative(pkt);

    skb_reset_network_header(skb);
    skb->protocol = htons(ETH_P_IP);

    info = cfpkt_info(pkt);
    hpad = (info->hdr_len + CFUSB_PAD_DESCR_SZ) & (CFUSB_ALIGNMENT - 1);

    if (skb_headroom(skb) < ETH_HLEN + CFUSB_PAD_DESCR_SZ + hpad) {
        pr_warn("Headroom to small\n");
        kfree_skb(skb);
        return -EIO;
    }
    memset(zeros, 0, hpad);

    cfpkt_add_head(pkt, zeros, hpad);
    cfpkt_add_head(pkt, &hpad, 1);
    cfpkt_add_head(pkt, usbl->tx_eth_hdr, sizeof(usbl->tx_eth_hdr));
    return layr->dn->transmit(layr->dn, pkt);
}

static void cfusbl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
                    int phyid)
{
    if (layr->up && layr->up->ctrlcmd)
        layr->up->ctrlcmd(layr->up, ctrl, layr->id);
}

struct cflayer *cfusbl_create(int phyid, u8 ethaddr[ETH_ALEN],
                    u8 braddr[ETH_ALEN])
{
    struct cfusbl *this = kmalloc(sizeof(struct cfusbl), GFP_ATOMIC);

    if (!this) {
        pr_warn("Out of memory\n");
        return NULL;
    }
    caif_assert(offsetof(struct cfusbl, layer) == 0);

    memset(this, 0, sizeof(struct cflayer));
    this->layer.receive = cfusbl_receive;
    this->layer.transmit = cfusbl_transmit;
    this->layer.ctrlcmd = cfusbl_ctrlcmd;
    snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "usb%d", phyid);
    this->layer.id = phyid;

    /*
     * Construct TX ethernet header:
     *  0-5 destination address
     *  5-11    source address
     *  12-13   protocol type
     */
    memcpy(&this->tx_eth_hdr[ETH_ALEN], braddr, ETH_ALEN);
    memcpy(&this->tx_eth_hdr[ETH_ALEN], ethaddr, ETH_ALEN);
    this->tx_eth_hdr[12] = cpu_to_be16(ETH_P_802_EX1) & 0xff;
    this->tx_eth_hdr[13] = (cpu_to_be16(ETH_P_802_EX1) >> 8) & 0xff;
    pr_debug("caif ethernet TX-header dst:%pM src:%pM type:%02x%02x\n",
            this->tx_eth_hdr, this->tx_eth_hdr + ETH_ALEN,
            this->tx_eth_hdr[12], this->tx_eth_hdr[13]);

    return (struct cflayer *) this;
}

static struct packet_type caif_usb_type __read_mostly = {
    .type = cpu_to_be16(ETH_P_802_EX1),
};

static int cfusbl_device_notify(struct notifier_block *me, unsigned long what,
                  void *arg)
{
    struct net_device *dev = arg;
    struct caif_dev_common common;
    struct cflayer *layer, *link_support;
    struct usbnet   *usbnet = netdev_priv(dev);
    struct usb_device   *usbdev = usbnet->udev;
    struct ethtool_drvinfo drvinfo;

    /*
     * Quirks: High-jack ethtool to find if we have a NCM device,
     * and find it's VID/PID.
     */
    if (dev->ethtool_ops == NULL || dev->ethtool_ops->get_drvinfo == NULL)
        return 0;

    dev->ethtool_ops->get_drvinfo(dev, &drvinfo);
    if (strncmp(drvinfo.driver, "cdc_ncm", 7) != 0)
        return 0;

    pr_debug("USB CDC NCM device VID:0x%4x PID:0x%4x\n",
        le16_to_cpu(usbdev->descriptor.idVendor),
        le16_to_cpu(usbdev->descriptor.idProduct));

    /* Check for VID/PID that supports CAIF */
    if (!(le16_to_cpu(usbdev->descriptor.idVendor) == STE_USB_VID &&
        le16_to_cpu(usbdev->descriptor.idProduct) == STE_USB_PID_CAIF))
        return 0;

    if (what == NETDEV_UNREGISTER)
        module_put(THIS_MODULE);

    if (what != NETDEV_REGISTER)
        return 0;

    __module_get(THIS_MODULE);

    memset(&common, 0, sizeof(common));
    common.use_frag = false;
    common.use_fcs = false;
    common.use_stx = false;
    common.link_select = CAIF_LINK_HIGH_BANDW;
    common.flowctrl = NULL;

    link_support = cfusbl_create(dev->ifindex, dev->dev_addr,
                    dev->broadcast);

    if (!link_support)
        return -ENOMEM;

    if (dev->num_tx_queues > 1)
        pr_warn("USB device uses more than one tx queue\n");

    caif_enroll_dev(dev, &common, link_support, CFUSB_MAX_HEADLEN,
            &layer, &caif_usb_type.func);
    if (!pack_added)
        dev_add_pack(&caif_usb_type);
    pack_added = true;

    strncpy(layer->name, dev->name,
            sizeof(layer->name) - 1);
    layer->name[sizeof(layer->name) - 1] = 0;

    return 0;
}

static struct notifier_block caif_device_notifier = {
    .notifier_call = cfusbl_device_notify,
    .priority = 0,
};

static int __init cfusbl_init(void)
{
    return register_netdevice_notifier(&caif_device_notifier);
}

static void __exit cfusbl_exit(void)
{
    unregister_netdevice_notifier(&caif_device_notifier);
    dev_remove_pack(&caif_usb_type);
}

module_init(cfusbl_init);
module_exit(cfusbl_exit);