f_ncm.c

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/*
 * f_ncm.c -- USB CDC Network (NCM) link function driver
 *
 * Copyright (C) 2010 Nokia Corporation
 * Contact: Yauheni Kaliuta <[email protected]>
 *
 * The driver borrows from f_ecm.c which is:
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2008 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>

#include <linux/usb/cdc.h>

#include "u_ether.h"

/*
 * This function is a "CDC Network Control Model" (CDC NCM) Ethernet link.
 * NCM is intended to be used with high-speed network attachments.
 *
 * Note that NCM requires the use of "alternate settings" for its data
 * interface.  This means that the set_alt() method has real work to do,
 * and also means that a get_alt() method is required.
 */

/* to trigger crc/non-crc ndp signature */

#define NCM_NDP_HDR_CRC_MASK    0x01000000
#define NCM_NDP_HDR_CRC     0x01000000
#define NCM_NDP_HDR_NOCRC   0x00000000

enum ncm_notify_state {
    NCM_NOTIFY_NONE,        /* don't notify */
    NCM_NOTIFY_CONNECT,     /* issue CONNECT next */
    NCM_NOTIFY_SPEED,       /* issue SPEED_CHANGE next */
};

struct f_ncm {
    struct gether           port;
    u8              ctrl_id, data_id;

    char                ethaddr[14];

    struct usb_ep           *notify;
    struct usb_request      *notify_req;
    u8              notify_state;
    bool                is_open;

    struct ndp_parser_opts      *parser_opts;
    bool                is_crc;

    /*
     * for notification, it is accessed from both
     * callback and ethernet open/close
     */
    spinlock_t          lock;
};

static inline struct f_ncm *func_to_ncm(struct usb_function *f)
{
    return container_of(f, struct f_ncm, port.func);
}

/* peak (theoretical) bulk transfer rate in bits-per-second */
static inline unsigned ncm_bitrate(struct usb_gadget *g)
{
    if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
        return 13 * 512 * 8 * 1000 * 8;
    else
        return 19 *  64 * 1 * 1000 * 8;
}

/*-------------------------------------------------------------------------*/

/*
 * We cannot group frames so use just the minimal size which ok to put
 * one max-size ethernet frame.
 * If the host can group frames, allow it to do that, 16K is selected,
 * because it's used by default by the current linux host driver
 */
#define NTB_DEFAULT_IN_SIZE USB_CDC_NCM_NTB_MIN_IN_SIZE
#define NTB_OUT_SIZE        16384

/*
 * skbs of size less than that will not be aligned
 * to NCM's dwNtbInMaxSize to save bus bandwidth
 */

#define MAX_TX_NONFIXED     (512 * 3)

#define FORMATS_SUPPORTED   (USB_CDC_NCM_NTB16_SUPPORTED |  \
                 USB_CDC_NCM_NTB32_SUPPORTED)

static struct usb_cdc_ncm_ntb_parameters ntb_parameters = {
    .wLength = sizeof ntb_parameters,
    .bmNtbFormatsSupported = cpu_to_le16(FORMATS_SUPPORTED),
    .dwNtbInMaxSize = cpu_to_le32(NTB_DEFAULT_IN_SIZE),
    .wNdpInDivisor = cpu_to_le16(4),
    .wNdpInPayloadRemainder = cpu_to_le16(0),
    .wNdpInAlignment = cpu_to_le16(4),

    .dwNtbOutMaxSize = cpu_to_le32(NTB_OUT_SIZE),
    .wNdpOutDivisor = cpu_to_le16(4),
    .wNdpOutPayloadRemainder = cpu_to_le16(0),
    .wNdpOutAlignment = cpu_to_le16(4),
};

/*
 * Use wMaxPacketSize big enough to fit CDC_NOTIFY_SPEED_CHANGE in one
 * packet, to simplify cancellation; and a big transfer interval, to
 * waste less bandwidth.
 */

#define LOG2_STATUS_INTERVAL_MSEC   5   /* 1 << 5 == 32 msec */
#define NCM_STATUS_BYTECOUNT        16  /* 8 byte header + data */

static struct usb_interface_assoc_descriptor ncm_iad_desc __initdata = {
    .bLength =      sizeof ncm_iad_desc,
    .bDescriptorType =  USB_DT_INTERFACE_ASSOCIATION,

    /* .bFirstInterface =   DYNAMIC, */
    .bInterfaceCount =  2,  /* control + data */
    .bFunctionClass =   USB_CLASS_COMM,
    .bFunctionSubClass =    USB_CDC_SUBCLASS_NCM,
    .bFunctionProtocol =    USB_CDC_PROTO_NONE,
    /* .iFunction =     DYNAMIC */
};

/* interface descriptor: */

static struct usb_interface_descriptor ncm_control_intf __initdata = {
    .bLength =      sizeof ncm_control_intf,
    .bDescriptorType =  USB_DT_INTERFACE,

    /* .bInterfaceNumber = DYNAMIC */
    .bNumEndpoints =    1,
    .bInterfaceClass =  USB_CLASS_COMM,
    .bInterfaceSubClass =   USB_CDC_SUBCLASS_NCM,
    .bInterfaceProtocol =   USB_CDC_PROTO_NONE,
    /* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc ncm_header_desc __initdata = {
    .bLength =      sizeof ncm_header_desc,
    .bDescriptorType =  USB_DT_CS_INTERFACE,
    .bDescriptorSubType =   USB_CDC_HEADER_TYPE,

    .bcdCDC =       cpu_to_le16(0x0110),
};

static struct usb_cdc_union_desc ncm_union_desc __initdata = {
    .bLength =      sizeof(ncm_union_desc),
    .bDescriptorType =  USB_DT_CS_INTERFACE,
    .bDescriptorSubType =   USB_CDC_UNION_TYPE,
    /* .bMasterInterface0 = DYNAMIC */
    /* .bSlaveInterface0 =  DYNAMIC */
};

static struct usb_cdc_ether_desc ecm_desc __initdata = {
    .bLength =      sizeof ecm_desc,
    .bDescriptorType =  USB_DT_CS_INTERFACE,
    .bDescriptorSubType =   USB_CDC_ETHERNET_TYPE,

    /* this descriptor actually adds value, surprise! */
    /* .iMACAddress = DYNAMIC */
    .bmEthernetStatistics = cpu_to_le32(0), /* no statistics */
    .wMaxSegmentSize =  cpu_to_le16(ETH_FRAME_LEN),
    .wNumberMCFilters = cpu_to_le16(0),
    .bNumberPowerFilters =  0,
};

#define NCAPS   (USB_CDC_NCM_NCAP_ETH_FILTER | USB_CDC_NCM_NCAP_CRC_MODE)

static struct usb_cdc_ncm_desc ncm_desc __initdata = {
    .bLength =      sizeof ncm_desc,
    .bDescriptorType =  USB_DT_CS_INTERFACE,
    .bDescriptorSubType =   USB_CDC_NCM_TYPE,

    .bcdNcmVersion =    cpu_to_le16(0x0100),
    /* can process SetEthernetPacketFilter */
    .bmNetworkCapabilities = NCAPS,
};

/* the default data interface has no endpoints ... */

static struct usb_interface_descriptor ncm_data_nop_intf __initdata = {
    .bLength =      sizeof ncm_data_nop_intf,
    .bDescriptorType =  USB_DT_INTERFACE,

    .bInterfaceNumber = 1,
    .bAlternateSetting =    0,
    .bNumEndpoints =    0,
    .bInterfaceClass =  USB_CLASS_CDC_DATA,
    .bInterfaceSubClass =   0,
    .bInterfaceProtocol =   USB_CDC_NCM_PROTO_NTB,
    /* .iInterface = DYNAMIC */
};

/* ... but the "real" data interface has two bulk endpoints */

static struct usb_interface_descriptor ncm_data_intf __initdata = {
    .bLength =      sizeof ncm_data_intf,
    .bDescriptorType =  USB_DT_INTERFACE,

    .bInterfaceNumber = 1,
    .bAlternateSetting =    1,
    .bNumEndpoints =    2,
    .bInterfaceClass =  USB_CLASS_CDC_DATA,
    .bInterfaceSubClass =   0,
    .bInterfaceProtocol =   USB_CDC_NCM_PROTO_NTB,
    /* .iInterface = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor fs_ncm_notify_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_INT,
    .wMaxPacketSize =   cpu_to_le16(NCM_STATUS_BYTECOUNT),
    .bInterval =        1 << LOG2_STATUS_INTERVAL_MSEC,
};

static struct usb_endpoint_descriptor fs_ncm_in_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor fs_ncm_out_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *ncm_fs_function[] __initdata = {
    (struct usb_descriptor_header *) &ncm_iad_desc,
    /* CDC NCM control descriptors */
    (struct usb_descriptor_header *) &ncm_control_intf,
    (struct usb_descriptor_header *) &ncm_header_desc,
    (struct usb_descriptor_header *) &ncm_union_desc,
    (struct usb_descriptor_header *) &ecm_desc,
    (struct usb_descriptor_header *) &ncm_desc,
    (struct usb_descriptor_header *) &fs_ncm_notify_desc,
    /* data interface, altsettings 0 and 1 */
    (struct usb_descriptor_header *) &ncm_data_nop_intf,
    (struct usb_descriptor_header *) &ncm_data_intf,
    (struct usb_descriptor_header *) &fs_ncm_in_desc,
    (struct usb_descriptor_header *) &fs_ncm_out_desc,
    NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor hs_ncm_notify_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_INT,
    .wMaxPacketSize =   cpu_to_le16(NCM_STATUS_BYTECOUNT),
    .bInterval =        LOG2_STATUS_INTERVAL_MSEC + 4,
};
static struct usb_endpoint_descriptor hs_ncm_in_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_endpoint_descriptor hs_ncm_out_desc __initdata = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,

    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_descriptor_header *ncm_hs_function[] __initdata = {
    (struct usb_descriptor_header *) &ncm_iad_desc,
    /* CDC NCM control descriptors */
    (struct usb_descriptor_header *) &ncm_control_intf,
    (struct usb_descriptor_header *) &ncm_header_desc,
    (struct usb_descriptor_header *) &ncm_union_desc,
    (struct usb_descriptor_header *) &ecm_desc,
    (struct usb_descriptor_header *) &ncm_desc,
    (struct usb_descriptor_header *) &hs_ncm_notify_desc,
    /* data interface, altsettings 0 and 1 */
    (struct usb_descriptor_header *) &ncm_data_nop_intf,
    (struct usb_descriptor_header *) &ncm_data_intf,
    (struct usb_descriptor_header *) &hs_ncm_in_desc,
    (struct usb_descriptor_header *) &hs_ncm_out_desc,
    NULL,
};

/* string descriptors: */

#define STRING_CTRL_IDX 0
#define STRING_MAC_IDX  1
#define STRING_DATA_IDX 2
#define STRING_IAD_IDX  3

static struct usb_string ncm_string_defs[] = {
    [STRING_CTRL_IDX].s = "CDC Network Control Model (NCM)",
    [STRING_MAC_IDX].s = NULL /* DYNAMIC */,
    [STRING_DATA_IDX].s = "CDC Network Data",
    [STRING_IAD_IDX].s = "CDC NCM",
    {  } /* end of list */
};

static struct usb_gadget_strings ncm_string_table = {
    .language =     0x0409, /* en-us */
    .strings =      ncm_string_defs,
};

static struct usb_gadget_strings *ncm_strings[] = {
    &ncm_string_table,
    NULL,
};

/*
 * Here are options for NCM Datagram Pointer table (NDP) parser.
 * There are 2 different formats: NDP16 and NDP32 in the spec (ch. 3),
 * in NDP16 offsets and sizes fields are 1 16bit word wide,
 * in NDP32 -- 2 16bit words wide. Also signatures are different.
 * To make the parser code the same, put the differences in the structure,
 * and switch pointers to the structures when the format is changed.
 */

struct ndp_parser_opts {
    u32     nth_sign;
    u32     ndp_sign;
    unsigned    nth_size;
    unsigned    ndp_size;
    unsigned    ndplen_align;
    /* sizes in u16 units */
    unsigned    dgram_item_len; /* index or length */
    unsigned    block_length;
    unsigned    fp_index;
    unsigned    reserved1;
    unsigned    reserved2;
    unsigned    next_fp_index;
};

#define INIT_NDP16_OPTS {                   \
        .nth_sign = USB_CDC_NCM_NTH16_SIGN,     \
        .ndp_sign = USB_CDC_NCM_NDP16_NOCRC_SIGN,   \
        .nth_size = sizeof(struct usb_cdc_ncm_nth16),   \
        .ndp_size = sizeof(struct usb_cdc_ncm_ndp16),   \
        .ndplen_align = 4,              \
        .dgram_item_len = 1,                \
        .block_length = 1,              \
        .fp_index = 1,                  \
        .reserved1 = 0,                 \
        .reserved2 = 0,                 \
        .next_fp_index = 1,             \
    }


#define INIT_NDP32_OPTS {                   \
        .nth_sign = USB_CDC_NCM_NTH32_SIGN,     \
        .ndp_sign = USB_CDC_NCM_NDP32_NOCRC_SIGN,   \
        .nth_size = sizeof(struct usb_cdc_ncm_nth32),   \
        .ndp_size = sizeof(struct usb_cdc_ncm_ndp32),   \
        .ndplen_align = 8,              \
        .dgram_item_len = 2,                \
        .block_length = 2,              \
        .fp_index = 2,                  \
        .reserved1 = 1,                 \
        .reserved2 = 2,                 \
        .next_fp_index = 2,             \
    }

static struct ndp_parser_opts ndp16_opts = INIT_NDP16_OPTS;
static struct ndp_parser_opts ndp32_opts = INIT_NDP32_OPTS;

static inline void put_ncm(__le16 **p, unsigned size, unsigned val)
{
    switch (size) {
    case 1:
        put_unaligned_le16((u16)val, *p);
        break;
    case 2:
        put_unaligned_le32((u32)val, *p);

        break;
    default:
        BUG();
    }

    *p += size;
}

static inline unsigned get_ncm(__le16 **p, unsigned size)
{
    unsigned tmp;

    switch (size) {
    case 1:
        tmp = get_unaligned_le16(*p);
        break;
    case 2:
        tmp = get_unaligned_le32(*p);
        break;
    default:
        BUG();
    }

    *p += size;
    return tmp;
}

/*-------------------------------------------------------------------------*/

static inline void ncm_reset_values(struct f_ncm *ncm)
{
    ncm->parser_opts = &ndp16_opts;
    ncm->is_crc = false;
    ncm->port.cdc_filter = DEFAULT_FILTER;

    /* doesn't make sense for ncm, fixed size used */
    ncm->port.header_len = 0;

    ncm->port.fixed_out_len = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
    ncm->port.fixed_in_len = NTB_DEFAULT_IN_SIZE;
}

/*
 * Context: ncm->lock held
 */
static void ncm_do_notify(struct f_ncm *ncm)
{
    struct usb_request      *req = ncm->notify_req;
    struct usb_cdc_notification *event;
    struct usb_composite_dev    *cdev = ncm->port.func.config->cdev;
    __le32              *data;
    int             status;

    /* notification already in flight? */
    if (!req)
        return;

    event = req->buf;
    switch (ncm->notify_state) {
    case NCM_NOTIFY_NONE:
        return;

    case NCM_NOTIFY_CONNECT:
        event->bNotificationType = USB_CDC_NOTIFY_NETWORK_CONNECTION;
        if (ncm->is_open)
            event->wValue = cpu_to_le16(1);
        else
            event->wValue = cpu_to_le16(0);
        event->wLength = 0;
        req->length = sizeof *event;

        DBG(cdev, "notify connect %s\n",
                ncm->is_open ? "true" : "false");
        ncm->notify_state = NCM_NOTIFY_NONE;
        break;

    case NCM_NOTIFY_SPEED:
        event->bNotificationType = USB_CDC_NOTIFY_SPEED_CHANGE;
        event->wValue = cpu_to_le16(0);
        event->wLength = cpu_to_le16(8);
        req->length = NCM_STATUS_BYTECOUNT;

        /* SPEED_CHANGE data is up/down speeds in bits/sec */
        data = req->buf + sizeof *event;
        data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));
        data[1] = data[0];

        DBG(cdev, "notify speed %d\n", ncm_bitrate(cdev->gadget));
        ncm->notify_state = NCM_NOTIFY_CONNECT;
        break;
    }
    event->bmRequestType = 0xA1;
    event->wIndex = cpu_to_le16(ncm->ctrl_id);

    ncm->notify_req = NULL;
    /*
     * In double buffering if there is a space in FIFO,
     * completion callback can be called right after the call,
     * so unlocking
     */
    spin_unlock(&ncm->lock);
    status = usb_ep_queue(ncm->notify, req, GFP_ATOMIC);
    spin_lock(&ncm->lock);
    if (status < 0) {
        ncm->notify_req = req;
        DBG(cdev, "notify --> %d\n", status);
    }
}

/*
 * Context: ncm->lock held
 */
static void ncm_notify(struct f_ncm *ncm)
{
    /*
     * NOTE on most versions of Linux, host side cdc-ethernet
     * won't listen for notifications until its netdevice opens.
     * The first notification then sits in the FIFO for a long
     * time, and the second one is queued.
     *
     * If ncm_notify() is called before the second (CONNECT)
     * notification is sent, then it will reset to send the SPEED
     * notificaion again (and again, and again), but it's not a problem
     */
    ncm->notify_state = NCM_NOTIFY_SPEED;
    ncm_do_notify(ncm);
}

static void ncm_notify_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct f_ncm            *ncm = req->context;
    struct usb_composite_dev    *cdev = ncm->port.func.config->cdev;
    struct usb_cdc_notification *event = req->buf;

    spin_lock(&ncm->lock);
    switch (req->status) {
    case 0:
        VDBG(cdev, "Notification %02x sent\n",
             event->bNotificationType);
        break;
    case -ECONNRESET:
    case -ESHUTDOWN:
        ncm->notify_state = NCM_NOTIFY_NONE;
        break;
    default:
        DBG(cdev, "event %02x --> %d\n",
            event->bNotificationType, req->status);
        break;
    }
    ncm->notify_req = req;
    ncm_do_notify(ncm);
    spin_unlock(&ncm->lock);
}

static void ncm_ep0out_complete(struct usb_ep *ep, struct usb_request *req)
{
    /* now for SET_NTB_INPUT_SIZE only */
    unsigned        in_size;
    struct usb_function *f = req->context;
    struct f_ncm        *ncm = func_to_ncm(f);
    struct usb_composite_dev *cdev = ep->driver_data;

    req->context = NULL;
    if (req->status || req->actual != req->length) {
        DBG(cdev, "Bad control-OUT transfer\n");
        goto invalid;
    }

    in_size = get_unaligned_le32(req->buf);
    if (in_size < USB_CDC_NCM_NTB_MIN_IN_SIZE ||
        in_size > le32_to_cpu(ntb_parameters.dwNtbInMaxSize)) {
        DBG(cdev, "Got wrong INPUT SIZE (%d) from host\n", in_size);
        goto invalid;
    }

    ncm->port.fixed_in_len = in_size;
    VDBG(cdev, "Set NTB INPUT SIZE %d\n", in_size);
    return;

invalid:
    usb_ep_set_halt(ep);
    return;
}

static int ncm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
    struct f_ncm        *ncm = func_to_ncm(f);
    struct usb_composite_dev *cdev = f->config->cdev;
    struct usb_request  *req = cdev->req;
    int         value = -EOPNOTSUPP;
    u16         w_index = le16_to_cpu(ctrl->wIndex);
    u16         w_value = le16_to_cpu(ctrl->wValue);
    u16         w_length = le16_to_cpu(ctrl->wLength);

    /*
     * composite driver infrastructure handles everything except
     * CDC class messages; interface activation uses set_alt().
     */
    switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
    case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
            | USB_CDC_SET_ETHERNET_PACKET_FILTER:
        /*
         * see 6.2.30: no data, wIndex = interface,
         * wValue = packet filter bitmap
         */
        if (w_length != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        DBG(cdev, "packet filter %02x\n", w_value);
        /*
         * REVISIT locking of cdc_filter.  This assumes the UDC
         * driver won't have a concurrent packet TX irq running on
         * another CPU; or that if it does, this write is atomic...
         */
        ncm->port.cdc_filter = w_value;
        value = 0;
        break;
    /*
     * and optionally:
     * case USB_CDC_SEND_ENCAPSULATED_COMMAND:
     * case USB_CDC_GET_ENCAPSULATED_RESPONSE:
     * case USB_CDC_SET_ETHERNET_MULTICAST_FILTERS:
     * case USB_CDC_SET_ETHERNET_PM_PATTERN_FILTER:
     * case USB_CDC_GET_ETHERNET_PM_PATTERN_FILTER:
     * case USB_CDC_GET_ETHERNET_STATISTIC:
     */

    case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_GET_NTB_PARAMETERS:

        if (w_length == 0 || w_value != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        value = w_length > sizeof ntb_parameters ?
            sizeof ntb_parameters : w_length;
        memcpy(req->buf, &ntb_parameters, value);
        VDBG(cdev, "Host asked NTB parameters\n");
        break;

    case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_GET_NTB_INPUT_SIZE:

        if (w_length < 4 || w_value != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        put_unaligned_le32(ncm->port.fixed_in_len, req->buf);
        value = 4;
        VDBG(cdev, "Host asked INPUT SIZE, sending %d\n",
             ncm->port.fixed_in_len);
        break;

    case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_SET_NTB_INPUT_SIZE:
    {
        if (w_length != 4 || w_value != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        req->complete = ncm_ep0out_complete;
        req->length = w_length;
        req->context = f;

        value = req->length;
        break;
    }

    case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_GET_NTB_FORMAT:
    {
        uint16_t format;

        if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        format = (ncm->parser_opts == &ndp16_opts) ? 0x0000 : 0x0001;
        put_unaligned_le16(format, req->buf);
        value = 2;
        VDBG(cdev, "Host asked NTB FORMAT, sending %d\n", format);
        break;
    }

    case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_SET_NTB_FORMAT:
    {
        if (w_length != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        switch (w_value) {
        case 0x0000:
            ncm->parser_opts = &ndp16_opts;
            DBG(cdev, "NCM16 selected\n");
            break;
        case 0x0001:
            ncm->parser_opts = &ndp32_opts;
            DBG(cdev, "NCM32 selected\n");
            break;
        default:
            goto invalid;
        }
        value = 0;
        break;
    }
    case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_GET_CRC_MODE:
    {
        uint16_t is_crc;

        if (w_length < 2 || w_value != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        is_crc = ncm->is_crc ? 0x0001 : 0x0000;
        put_unaligned_le16(is_crc, req->buf);
        value = 2;
        VDBG(cdev, "Host asked CRC MODE, sending %d\n", is_crc);
        break;
    }

    case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
        | USB_CDC_SET_CRC_MODE:
    {
        int ndp_hdr_crc = 0;

        if (w_length != 0 || w_index != ncm->ctrl_id)
            goto invalid;
        switch (w_value) {
        case 0x0000:
            ncm->is_crc = false;
            ndp_hdr_crc = NCM_NDP_HDR_NOCRC;
            DBG(cdev, "non-CRC mode selected\n");
            break;
        case 0x0001:
            ncm->is_crc = true;
            ndp_hdr_crc = NCM_NDP_HDR_CRC;
            DBG(cdev, "CRC mode selected\n");
            break;
        default:
            goto invalid;
        }
        ncm->parser_opts->ndp_sign &= ~NCM_NDP_HDR_CRC_MASK;
        ncm->parser_opts->ndp_sign |= ndp_hdr_crc;
        value = 0;
        break;
    }

    /* and disabled in ncm descriptor: */
    /* case USB_CDC_GET_NET_ADDRESS: */
    /* case USB_CDC_SET_NET_ADDRESS: */
    /* case USB_CDC_GET_MAX_DATAGRAM_SIZE: */
    /* case USB_CDC_SET_MAX_DATAGRAM_SIZE: */

    default:
invalid:
        DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
            ctrl->bRequestType, ctrl->bRequest,
            w_value, w_index, w_length);
    }

    /* respond with data transfer or status phase? */
    if (value >= 0) {
        DBG(cdev, "ncm req%02x.%02x v%04x i%04x l%d\n",
            ctrl->bRequestType, ctrl->bRequest,
            w_value, w_index, w_length);
        req->zero = 0;
        req->length = value;
        value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
        if (value < 0)
            ERROR(cdev, "ncm req %02x.%02x response err %d\n",
                    ctrl->bRequestType, ctrl->bRequest,
                    value);
    }

    /* device either stalls (value < 0) or reports success */
    return value;
}


static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
    struct f_ncm        *ncm = func_to_ncm(f);
    struct usb_composite_dev *cdev = f->config->cdev;

    /* Control interface has only altsetting 0 */
    if (intf == ncm->ctrl_id) {
        if (alt != 0)
            goto fail;

        if (ncm->notify->driver_data) {
            DBG(cdev, "reset ncm control %d\n", intf);
            usb_ep_disable(ncm->notify);
        }

        if (!(ncm->notify->desc)) {
            DBG(cdev, "init ncm ctrl %d\n", intf);
            if (config_ep_by_speed(cdev->gadget, f, ncm->notify))
                goto fail;
        }
        usb_ep_enable(ncm->notify);
        ncm->notify->driver_data = ncm;

    /* Data interface has two altsettings, 0 and 1 */
    } else if (intf == ncm->data_id) {
        if (alt > 1)
            goto fail;

        if (ncm->port.in_ep->driver_data) {
            DBG(cdev, "reset ncm\n");
            gether_disconnect(&ncm->port);
            ncm_reset_values(ncm);
        }

        /*
         * CDC Network only sends data in non-default altsettings.
         * Changing altsettings resets filters, statistics, etc.
         */
        if (alt == 1) {
            struct net_device   *net;

            if (!ncm->port.in_ep->desc ||
                !ncm->port.out_ep->desc) {
                DBG(cdev, "init ncm\n");
                if (config_ep_by_speed(cdev->gadget, f,
                               ncm->port.in_ep) ||
                    config_ep_by_speed(cdev->gadget, f,
                               ncm->port.out_ep)) {
                    ncm->port.in_ep->desc = NULL;
                    ncm->port.out_ep->desc = NULL;
                    goto fail;
                }
            }

            /* TODO */
            /* Enable zlps by default for NCM conformance;
             * override for musb_hdrc (avoids txdma ovhead)
             */
            ncm->port.is_zlp_ok = !(
                gadget_is_musbhdrc(cdev->gadget)
                );
            ncm->port.cdc_filter = DEFAULT_FILTER;
            DBG(cdev, "activate ncm\n");
            net = gether_connect(&ncm->port);
            if (IS_ERR(net))
                return PTR_ERR(net);
        }

        spin_lock(&ncm->lock);
        ncm_notify(ncm);
        spin_unlock(&ncm->lock);
    } else
        goto fail;

    return 0;
fail:
    return -EINVAL;
}

/*
 * Because the data interface supports multiple altsettings,
 * this NCM function *MUST* implement a get_alt() method.
 */
static int ncm_get_alt(struct usb_function *f, unsigned intf)
{
    struct f_ncm        *ncm = func_to_ncm(f);

    if (intf == ncm->ctrl_id)
        return 0;
    return ncm->port.in_ep->driver_data ? 1 : 0;
}

static struct sk_buff *ncm_wrap_ntb(struct gether *port,
                    struct sk_buff *skb)
{
    struct f_ncm    *ncm = func_to_ncm(&port->func);
    struct sk_buff  *skb2;
    int     ncb_len = 0;
    __le16      *tmp;
    int     div = ntb_parameters.wNdpInDivisor;
    int     rem = ntb_parameters.wNdpInPayloadRemainder;
    int     pad;
    int     ndp_align = ntb_parameters.wNdpInAlignment;
    int     ndp_pad;
    unsigned    max_size = ncm->port.fixed_in_len;
    struct ndp_parser_opts *opts = ncm->parser_opts;
    unsigned    crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;

    ncb_len += opts->nth_size;
    ndp_pad = ALIGN(ncb_len, ndp_align) - ncb_len;
    ncb_len += ndp_pad;
    ncb_len += opts->ndp_size;
    ncb_len += 2 * 2 * opts->dgram_item_len; /* Datagram entry */
    ncb_len += 2 * 2 * opts->dgram_item_len; /* Zero datagram entry */
    pad = ALIGN(ncb_len, div) + rem - ncb_len;
    ncb_len += pad;

    if (ncb_len + skb->len + crc_len > max_size) {
        dev_kfree_skb_any(skb);
        return NULL;
    }

    skb2 = skb_copy_expand(skb, ncb_len,
                   max_size - skb->len - ncb_len - crc_len,
                   GFP_ATOMIC);
    dev_kfree_skb_any(skb);
    if (!skb2)
        return NULL;

    skb = skb2;

    tmp = (void *) skb_push(skb, ncb_len);
    memset(tmp, 0, ncb_len);

    put_unaligned_le32(opts->nth_sign, tmp); /* dwSignature */
    tmp += 2;
    /* wHeaderLength */
    put_unaligned_le16(opts->nth_size, tmp++);
    tmp++; /* skip wSequence */
    put_ncm(&tmp, opts->block_length, skb->len); /* (d)wBlockLength */
    /* (d)wFpIndex */
    /* the first pointer is right after the NTH + align */
    put_ncm(&tmp, opts->fp_index, opts->nth_size + ndp_pad);

    tmp = (void *)tmp + ndp_pad;

    /* NDP */
    put_unaligned_le32(opts->ndp_sign, tmp); /* dwSignature */
    tmp += 2;
    /* wLength */
    put_unaligned_le16(ncb_len - opts->nth_size - pad, tmp++);

    tmp += opts->reserved1;
    tmp += opts->next_fp_index; /* skip reserved (d)wNextFpIndex */
    tmp += opts->reserved2;

    if (ncm->is_crc) {
        uint32_t crc;

        crc = ~crc32_le(~0,
                skb->data + ncb_len,
                skb->len - ncb_len);
        put_unaligned_le32(crc, skb->data + skb->len);
        skb_put(skb, crc_len);
    }

    /* (d)wDatagramIndex[0] */
    put_ncm(&tmp, opts->dgram_item_len, ncb_len);
    /* (d)wDatagramLength[0] */
    put_ncm(&tmp, opts->dgram_item_len, skb->len - ncb_len);
    /* (d)wDatagramIndex[1] and  (d)wDatagramLength[1] already zeroed */

    if (skb->len > MAX_TX_NONFIXED)
        memset(skb_put(skb, max_size - skb->len),
               0, max_size - skb->len);

    return skb;
}

static int ncm_unwrap_ntb(struct gether *port,
              struct sk_buff *skb,
              struct sk_buff_head *list)
{
    struct f_ncm    *ncm = func_to_ncm(&port->func);
    __le16      *tmp = (void *) skb->data;
    unsigned    index, index2;
    unsigned    dg_len, dg_len2;
    unsigned    ndp_len;
    struct sk_buff  *skb2;
    int     ret = -EINVAL;
    unsigned    max_size = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
    struct ndp_parser_opts *opts = ncm->parser_opts;
    unsigned    crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
    int     dgram_counter;

    /* dwSignature */
    if (get_unaligned_le32(tmp) != opts->nth_sign) {
        INFO(port->func.config->cdev, "Wrong NTH SIGN, skblen %d\n",
            skb->len);
        print_hex_dump(KERN_INFO, "HEAD:", DUMP_PREFIX_ADDRESS, 32, 1,
                   skb->data, 32, false);

        goto err;
    }
    tmp += 2;
    /* wHeaderLength */
    if (get_unaligned_le16(tmp++) != opts->nth_size) {
        INFO(port->func.config->cdev, "Wrong NTB headersize\n");
        goto err;
    }
    tmp++; /* skip wSequence */

    /* (d)wBlockLength */
    if (get_ncm(&tmp, opts->block_length) > max_size) {
        INFO(port->func.config->cdev, "OUT size exceeded\n");
        goto err;
    }

    index = get_ncm(&tmp, opts->fp_index);
    /* NCM 3.2 */
    if (((index % 4) != 0) && (index < opts->nth_size)) {
        INFO(port->func.config->cdev, "Bad index: %x\n",
            index);
        goto err;
    }

    /* walk through NDP */
    tmp = ((void *)skb->data) + index;
    if (get_unaligned_le32(tmp) != opts->ndp_sign) {
        INFO(port->func.config->cdev, "Wrong NDP SIGN\n");
        goto err;
    }
    tmp += 2;

    ndp_len = get_unaligned_le16(tmp++);
    /*
     * NCM 3.3.1
     * entry is 2 items
     * item size is 16/32 bits, opts->dgram_item_len * 2 bytes
     * minimal: struct usb_cdc_ncm_ndpX + normal entry + zero entry
     */
    if ((ndp_len < opts->ndp_size + 2 * 2 * (opts->dgram_item_len * 2))
        || (ndp_len % opts->ndplen_align != 0)) {
        INFO(port->func.config->cdev, "Bad NDP length: %x\n", ndp_len);
        goto err;
    }
    tmp += opts->reserved1;
    tmp += opts->next_fp_index; /* skip reserved (d)wNextFpIndex */
    tmp += opts->reserved2;

    ndp_len -= opts->ndp_size;
    index2 = get_ncm(&tmp, opts->dgram_item_len);
    dg_len2 = get_ncm(&tmp, opts->dgram_item_len);
    dgram_counter = 0;

    do {
        index = index2;
        dg_len = dg_len2;
        if (dg_len < 14 + crc_len) { /* ethernet header + crc */
            INFO(port->func.config->cdev, "Bad dgram length: %x\n",
                 dg_len);
            goto err;
        }
        if (ncm->is_crc) {
            uint32_t crc, crc2;

            crc = get_unaligned_le32(skb->data +
                         index + dg_len - crc_len);
            crc2 = ~crc32_le(~0,
                     skb->data + index,
                     dg_len - crc_len);
            if (crc != crc2) {
                INFO(port->func.config->cdev, "Bad CRC\n");
                goto err;
            }
        }

        index2 = get_ncm(&tmp, opts->dgram_item_len);
        dg_len2 = get_ncm(&tmp, opts->dgram_item_len);

        if (index2 == 0 || dg_len2 == 0) {
            skb2 = skb;
        } else {
            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (skb2 == NULL)
                goto err;
        }

        if (!skb_pull(skb2, index)) {
            ret = -EOVERFLOW;
            goto err;
        }

        skb_trim(skb2, dg_len - crc_len);
        skb_queue_tail(list, skb2);

        ndp_len -= 2 * (opts->dgram_item_len * 2);

        dgram_counter++;

        if (index2 == 0 || dg_len2 == 0)
            break;
    } while (ndp_len > 2 * (opts->dgram_item_len * 2)); /* zero entry */

    VDBG(port->func.config->cdev,
         "Parsed NTB with %d frames\n", dgram_counter);
    return 0;
err:
    skb_queue_purge(list);
    dev_kfree_skb_any(skb);
    return ret;
}

static void ncm_disable(struct usb_function *f)
{
    struct f_ncm        *ncm = func_to_ncm(f);
    struct usb_composite_dev *cdev = f->config->cdev;

    DBG(cdev, "ncm deactivated\n");

    if (ncm->port.in_ep->driver_data)
        gether_disconnect(&ncm->port);

    if (ncm->notify->driver_data) {
        usb_ep_disable(ncm->notify);
        ncm->notify->driver_data = NULL;
        ncm->notify->desc = NULL;
    }
}

/*-------------------------------------------------------------------------*/

/*
 * Callbacks let us notify the host about connect/disconnect when the
 * net device is opened or closed.
 *
 * For testing, note that link states on this side include both opened
 * and closed variants of:
 *
 *   - disconnected/unconfigured
 *   - configured but inactive (data alt 0)
 *   - configured and active (data alt 1)
 *
 * Each needs to be tested with unplug, rmmod, SET_CONFIGURATION, and
 * SET_INTERFACE (altsetting).  Remember also that "configured" doesn't
 * imply the host is actually polling the notification endpoint, and
 * likewise that "active" doesn't imply it's actually using the data
 * endpoints for traffic.
 */

static void ncm_open(struct gether *geth)
{
    struct f_ncm        *ncm = func_to_ncm(&geth->func);

    DBG(ncm->port.func.config->cdev, "%s\n", __func__);

    spin_lock(&ncm->lock);
    ncm->is_open = true;
    ncm_notify(ncm);
    spin_unlock(&ncm->lock);
}

static void ncm_close(struct gether *geth)
{
    struct f_ncm        *ncm = func_to_ncm(&geth->func);

    DBG(ncm->port.func.config->cdev, "%s\n", __func__);

    spin_lock(&ncm->lock);
    ncm->is_open = false;
    ncm_notify(ncm);
    spin_unlock(&ncm->lock);
}

/*-------------------------------------------------------------------------*/

/* ethernet function driver setup/binding */

static int __init
ncm_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct usb_composite_dev *cdev = c->cdev;
    struct f_ncm        *ncm = func_to_ncm(f);
    int         status;
    struct usb_ep       *ep;

    /* allocate instance-specific interface IDs */
    status = usb_interface_id(c, f);
    if (status < 0)
        goto fail;
    ncm->ctrl_id = status;
    ncm_iad_desc.bFirstInterface = status;

    ncm_control_intf.bInterfaceNumber = status;
    ncm_union_desc.bMasterInterface0 = status;

    status = usb_interface_id(c, f);
    if (status < 0)
        goto fail;
    ncm->data_id = status;

    ncm_data_nop_intf.bInterfaceNumber = status;
    ncm_data_intf.bInterfaceNumber = status;
    ncm_union_desc.bSlaveInterface0 = status;

    status = -ENODEV;

    /* allocate instance-specific endpoints */
    ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_in_desc);
    if (!ep)
        goto fail;
    ncm->port.in_ep = ep;
    ep->driver_data = cdev; /* claim */

    ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_out_desc);
    if (!ep)
        goto fail;
    ncm->port.out_ep = ep;
    ep->driver_data = cdev; /* claim */

    ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_notify_desc);
    if (!ep)
        goto fail;
    ncm->notify = ep;
    ep->driver_data = cdev; /* claim */

    status = -ENOMEM;

    /* allocate notification request and buffer */
    ncm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
    if (!ncm->notify_req)
        goto fail;
    ncm->notify_req->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL);
    if (!ncm->notify_req->buf)
        goto fail;
    ncm->notify_req->context = ncm;
    ncm->notify_req->complete = ncm_notify_complete;

    /* copy descriptors, and track endpoint copies */
    f->descriptors = usb_copy_descriptors(ncm_fs_function);
    if (!f->descriptors)
        goto fail;

    /*
     * support all relevant hardware speeds... we expect that when
     * hardware is dual speed, all bulk-capable endpoints work at
     * both speeds
     */
    if (gadget_is_dualspeed(c->cdev->gadget)) {
        hs_ncm_in_desc.bEndpointAddress =
                fs_ncm_in_desc.bEndpointAddress;
        hs_ncm_out_desc.bEndpointAddress =
                fs_ncm_out_desc.bEndpointAddress;
        hs_ncm_notify_desc.bEndpointAddress =
                fs_ncm_notify_desc.bEndpointAddress;

        /* copy descriptors, and track endpoint copies */
        f->hs_descriptors = usb_copy_descriptors(ncm_hs_function);
        if (!f->hs_descriptors)
            goto fail;
    }

    /*
     * NOTE:  all that is done without knowing or caring about
     * the network link ... which is unavailable to this code
     * until we're activated via set_alt().
     */

    ncm->port.open = ncm_open;
    ncm->port.close = ncm_close;

    DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
            gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
            ncm->port.in_ep->name, ncm->port.out_ep->name,
            ncm->notify->name);
    return 0;

fail:
    if (f->descriptors)
        usb_free_descriptors(f->descriptors);

    if (ncm->notify_req) {
        kfree(ncm->notify_req->buf);
        usb_ep_free_request(ncm->notify, ncm->notify_req);
    }

    /* we might as well release our claims on endpoints */
    if (ncm->notify)
        ncm->notify->driver_data = NULL;
    if (ncm->port.out_ep->desc)
        ncm->port.out_ep->driver_data = NULL;
    if (ncm->port.in_ep->desc)
        ncm->port.in_ep->driver_data = NULL;

    ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);

    return status;
}

static void
ncm_unbind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_ncm        *ncm = func_to_ncm(f);

    DBG(c->cdev, "ncm unbind\n");

    if (gadget_is_dualspeed(c->cdev->gadget))
        usb_free_descriptors(f->hs_descriptors);
    usb_free_descriptors(f->descriptors);

    kfree(ncm->notify_req->buf);
    usb_ep_free_request(ncm->notify, ncm->notify_req);

    ncm_string_defs[1].s = NULL;
    kfree(ncm);
}

int __init ncm_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
{
    struct f_ncm    *ncm;
    int     status;

    if (!can_support_ecm(c->cdev->gadget) || !ethaddr)
        return -EINVAL;

    /* maybe allocate device-global string IDs */
    if (ncm_string_defs[0].id == 0) {

        /* control interface label */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ncm_string_defs[STRING_CTRL_IDX].id = status;
        ncm_control_intf.iInterface = status;

        /* data interface label */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ncm_string_defs[STRING_DATA_IDX].id = status;
        ncm_data_nop_intf.iInterface = status;
        ncm_data_intf.iInterface = status;

        /* MAC address */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ncm_string_defs[STRING_MAC_IDX].id = status;
        ecm_desc.iMACAddress = status;

        /* IAD */
        status = usb_string_id(c->cdev);
        if (status < 0)
            return status;
        ncm_string_defs[STRING_IAD_IDX].id = status;
        ncm_iad_desc.iFunction = status;
    }

    /* allocate and initialize one new instance */
    ncm = kzalloc(sizeof *ncm, GFP_KERNEL);
    if (!ncm)
        return -ENOMEM;

    /* export host's Ethernet address in CDC format */
    snprintf(ncm->ethaddr, sizeof ncm->ethaddr, "%pm", ethaddr);
    ncm_string_defs[1].s = ncm->ethaddr;

    spin_lock_init(&ncm->lock);
    ncm_reset_values(ncm);
    ncm->port.is_fixed = true;

    ncm->port.func.name = "cdc_network";
    ncm->port.func.strings = ncm_strings;
    /* descriptors are per-instance copies */
    ncm->port.func.bind = ncm_bind;
    ncm->port.func.unbind = ncm_unbind;
    ncm->port.func.set_alt = ncm_set_alt;
    ncm->port.func.get_alt = ncm_get_alt;
    ncm->port.func.setup = ncm_setup;
    ncm->port.func.disable = ncm_disable;

    ncm->port.wrap = ncm_wrap_ntb;
    ncm->port.unwrap = ncm_unwrap_ntb;

    status = usb_add_function(c, &ncm->port.func);
    if (status) {
        ncm_string_defs[1].s = NULL;
        kfree(ncm);
    }
    return status;
}