f_eem.c

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/*
 * f_eem.c -- USB CDC Ethernet (EEM) link function driver
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2008 Nokia Corporation
 * Copyright (C) 2009 EF Johnson Technologies
 *
 * 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/slab.h>

#include "u_ether.h"

#define EEM_HLEN 2

/*
 * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
 * Ethernet link.
 */

struct f_eem {
    struct gether           port;
    u8              ctrl_id;
};

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

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

/* interface descriptor: */

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

    /* .bInterfaceNumber = DYNAMIC */
    .bNumEndpoints =    2,
    .bInterfaceClass =  USB_CLASS_COMM,
    .bInterfaceSubClass =   USB_CDC_SUBCLASS_EEM,
    .bInterfaceProtocol =   USB_CDC_PROTO_EEM,
    /* .iInterface = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor eem_fs_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 eem_fs_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 *eem_fs_function[] __initdata = {
    /* CDC EEM control descriptors */
    (struct usb_descriptor_header *) &eem_intf,
    (struct usb_descriptor_header *) &eem_fs_in_desc,
    (struct usb_descriptor_header *) &eem_fs_out_desc,
    NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor eem_hs_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 eem_hs_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 *eem_hs_function[] __initdata = {
    /* CDC EEM control descriptors */
    (struct usb_descriptor_header *) &eem_intf,
    (struct usb_descriptor_header *) &eem_hs_in_desc,
    (struct usb_descriptor_header *) &eem_hs_out_desc,
    NULL,
};

/* super speed support: */

static struct usb_endpoint_descriptor eem_ss_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(1024),
};

static struct usb_endpoint_descriptor eem_ss_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(1024),
};

static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc __initdata = {
    .bLength =      sizeof eem_ss_bulk_comp_desc,
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,

    /* the following 2 values can be tweaked if necessary */
    /* .bMaxBurst =     0, */
    /* .bmAttributes =  0, */
};

static struct usb_descriptor_header *eem_ss_function[] __initdata = {
    /* CDC EEM control descriptors */
    (struct usb_descriptor_header *) &eem_intf,
    (struct usb_descriptor_header *) &eem_ss_in_desc,
    (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
    (struct usb_descriptor_header *) &eem_ss_out_desc,
    (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
    NULL,
};

/* string descriptors: */

static struct usb_string eem_string_defs[] = {
    [0].s = "CDC Ethernet Emulation Model (EEM)",
    {  } /* end of list */
};

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

static struct usb_gadget_strings *eem_strings[] = {
    &eem_string_table,
    NULL,
};

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

static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
    struct usb_composite_dev *cdev = f->config->cdev;
    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);

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

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


static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
    struct f_eem        *eem = func_to_eem(f);
    struct usb_composite_dev *cdev = f->config->cdev;
    struct net_device   *net;

    /* we know alt == 0, so this is an activation or a reset */
    if (alt != 0)
        goto fail;

    if (intf == eem->ctrl_id) {

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

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

        /* zlps should not occur because zero-length EEM packets
         * will be inserted in those cases where they would occur
         */
        eem->port.is_zlp_ok = 1;
        eem->port.cdc_filter = DEFAULT_FILTER;
        DBG(cdev, "activate eem\n");
        net = gether_connect(&eem->port);
        if (IS_ERR(net))
            return PTR_ERR(net);
    } else
        goto fail;

    return 0;
fail:
    return -EINVAL;
}

static void eem_disable(struct usb_function *f)
{
    struct f_eem        *eem = func_to_eem(f);
    struct usb_composite_dev *cdev = f->config->cdev;

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

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

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

/* EEM function driver setup/binding */

static int __init
eem_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct usb_composite_dev *cdev = c->cdev;
    struct f_eem        *eem = func_to_eem(f);
    int         status;
    struct usb_ep       *ep;

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

    status = -ENODEV;

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

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

    status = -ENOMEM;

    /* copy descriptors, and track endpoint copies */
    f->descriptors = usb_copy_descriptors(eem_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)) {
        eem_hs_in_desc.bEndpointAddress =
                eem_fs_in_desc.bEndpointAddress;
        eem_hs_out_desc.bEndpointAddress =
                eem_fs_out_desc.bEndpointAddress;

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

    if (gadget_is_superspeed(c->cdev->gadget)) {
        eem_ss_in_desc.bEndpointAddress =
                eem_fs_in_desc.bEndpointAddress;
        eem_ss_out_desc.bEndpointAddress =
                eem_fs_out_desc.bEndpointAddress;

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

    DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
            gadget_is_superspeed(c->cdev->gadget) ? "super" :
            gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
            eem->port.in_ep->name, eem->port.out_ep->name);
    return 0;

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

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

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

    return status;
}

static void
eem_unbind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_eem    *eem = func_to_eem(f);

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

    if (gadget_is_superspeed(c->cdev->gadget))
        usb_free_descriptors(f->ss_descriptors);
    if (gadget_is_dualspeed(c->cdev->gadget))
        usb_free_descriptors(f->hs_descriptors);
    usb_free_descriptors(f->descriptors);
    kfree(eem);
}

static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct sk_buff *skb = (struct sk_buff *)req->context;

    dev_kfree_skb_any(skb);
}

/*
 * Add the EEM header and ethernet checksum.
 * We currently do not attempt to put multiple ethernet frames
 * into a single USB transfer
 */
static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
{
    struct sk_buff  *skb2 = NULL;
    struct usb_ep   *in = port->in_ep;
    int     padlen = 0;
    u16     len = skb->len;

    if (!skb_cloned(skb)) {
        int headroom = skb_headroom(skb);
        int tailroom = skb_tailroom(skb);

        /* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
         * stick two bytes of zero-length EEM packet on the end.
         */
        if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
            padlen += 2;

        if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
                (headroom >= EEM_HLEN))
            goto done;
    }

    skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
    dev_kfree_skb_any(skb);
    skb = skb2;
    if (!skb)
        return skb;

done:
    /* use the "no CRC" option */
    put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));

    /* EEM packet header format:
     * b0..13:  length of ethernet frame
     * b14:     bmCRC (0 == sentinel CRC)
     * b15:     bmType (0 == data)
     */
    len = skb->len;
    put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));

    /* add a zero-length EEM packet, if needed */
    if (padlen)
        put_unaligned_le16(0, skb_put(skb, 2));

    return skb;
}

/*
 * Remove the EEM header.  Note that there can be many EEM packets in a single
 * USB transfer, so we need to break them out and handle them independently.
 */
static int eem_unwrap(struct gether *port,
            struct sk_buff *skb,
            struct sk_buff_head *list)
{
    struct usb_composite_dev    *cdev = port->func.config->cdev;
    int             status = 0;

    do {
        struct sk_buff  *skb2;
        u16     header;
        u16     len = 0;

        if (skb->len < EEM_HLEN) {
            status = -EINVAL;
            DBG(cdev, "invalid EEM header\n");
            goto error;
        }

        /* remove the EEM header */
        header = get_unaligned_le16(skb->data);
        skb_pull(skb, EEM_HLEN);

        /* EEM packet header format:
         * b0..14:  EEM type dependent (data or command)
         * b15:     bmType (0 == data, 1 == command)
         */
        if (header & BIT(15)) {
            struct usb_request  *req = cdev->req;
            u16         bmEEMCmd;

            /* EEM command packet format:
             * b0..10:  bmEEMCmdParam
             * b11..13: bmEEMCmd
             * b14:     reserved (must be zero)
             * b15:     bmType (1 == command)
             */
            if (header & BIT(14))
                continue;

            bmEEMCmd = (header >> 11) & 0x7;
            switch (bmEEMCmd) {
            case 0: /* echo */
                len = header & 0x7FF;
                if (skb->len < len) {
                    status = -EOVERFLOW;
                    goto error;
                }

                skb2 = skb_clone(skb, GFP_ATOMIC);
                if (unlikely(!skb2)) {
                    DBG(cdev, "EEM echo response error\n");
                    goto next;
                }
                skb_trim(skb2, len);
                put_unaligned_le16(BIT(15) | BIT(11) | len,
                            skb_push(skb2, 2));
                skb_copy_bits(skb2, 0, req->buf, skb2->len);
                req->length = skb2->len;
                req->complete = eem_cmd_complete;
                req->zero = 1;
                req->context = skb2;
                if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
                    DBG(cdev, "echo response queue fail\n");
                break;

            case 1:  /* echo response */
            case 2:  /* suspend hint */
            case 3:  /* response hint */
            case 4:  /* response complete hint */
            case 5:  /* tickle */
            default: /* reserved */
                continue;
            }
        } else {
            u32     crc, crc2;
            struct sk_buff  *skb3;

            /* check for zero-length EEM packet */
            if (header == 0)
                continue;

            /* EEM data packet format:
             * b0..13:  length of ethernet frame
             * b14:     bmCRC (0 == sentinel, 1 == calculated)
             * b15:     bmType (0 == data)
             */
            len = header & 0x3FFF;
            if ((skb->len < len)
                    || (len < (ETH_HLEN + ETH_FCS_LEN))) {
                status = -EINVAL;
                goto error;
            }

            /* validate CRC */
            if (header & BIT(14)) {
                crc = get_unaligned_le32(skb->data + len
                            - ETH_FCS_LEN);
                crc2 = ~crc32_le(~0,
                        skb->data, len - ETH_FCS_LEN);
            } else {
                crc = get_unaligned_be32(skb->data + len
                            - ETH_FCS_LEN);
                crc2 = 0xdeadbeef;
            }
            if (crc != crc2) {
                DBG(cdev, "invalid EEM CRC\n");
                goto next;
            }

            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (unlikely(!skb2)) {
                DBG(cdev, "unable to unframe EEM packet\n");
                continue;
            }
            skb_trim(skb2, len - ETH_FCS_LEN);

            skb3 = skb_copy_expand(skb2,
                        NET_IP_ALIGN,
                        0,
                        GFP_ATOMIC);
            if (unlikely(!skb3)) {
                DBG(cdev, "unable to realign EEM packet\n");
                dev_kfree_skb_any(skb2);
                continue;
            }
            dev_kfree_skb_any(skb2);
            skb_queue_tail(list, skb3);
        }
next:
        skb_pull(skb, len);
    } while (skb->len);

error:
    dev_kfree_skb_any(skb);
    return status;
}

int __init eem_bind_config(struct usb_configuration *c)
{
    struct f_eem    *eem;
    int     status;

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

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

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

    eem->port.cdc_filter = DEFAULT_FILTER;

    eem->port.func.name = "cdc_eem";
    eem->port.func.strings = eem_strings;
    /* descriptors are per-instance copies */
    eem->port.func.bind = eem_bind;
    eem->port.func.unbind = eem_unbind;
    eem->port.func.set_alt = eem_set_alt;
    eem->port.func.setup = eem_setup;
    eem->port.func.disable = eem_disable;
    eem->port.wrap = eem_wrap;
    eem->port.unwrap = eem_unwrap;
    eem->port.header_len = EEM_HLEN;

    status = usb_add_function(c, &eem->port.func);
    if (status)
        kfree(eem);
    return status;
}