ether.c

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/*
 * ether.c -- Ethernet gadget driver, with CDC and non-CDC options
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
 * 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.
 */

/* #define VERBOSE_DEBUG */

#include <linux/kernel.h>

#if defined USB_ETH_RNDIS
#  undef USB_ETH_RNDIS
#endif
#ifdef CONFIG_USB_ETH_RNDIS
#  define USB_ETH_RNDIS y
#endif

#include "u_ether.h"


/*
 * Ethernet gadget driver -- with CDC and non-CDC options
 * Builds on hardware support for a full duplex link.
 *
 * CDC Ethernet is the standard USB solution for sending Ethernet frames
 * using USB.  Real hardware tends to use the same framing protocol but look
 * different for control features.  This driver strongly prefers to use
 * this USB-IF standard as its open-systems interoperability solution;
 * most host side USB stacks (except from Microsoft) support it.
 *
 * This is sometimes called "CDC ECM" (Ethernet Control Model) to support
 * TLA-soup.  "CDC ACM" (Abstract Control Model) is for modems, and a new
 * "CDC EEM" (Ethernet Emulation Model) is starting to spread.
 *
 * There's some hardware that can't talk CDC ECM.  We make that hardware
 * implement a "minimalist" vendor-agnostic CDC core:  same framing, but
 * link-level setup only requires activating the configuration.  Only the
 * endpoint descriptors, and product/vendor IDs, are relevant; no control
 * operations are available.  Linux supports it, but other host operating
 * systems may not.  (This is a subset of CDC Ethernet.)
 *
 * It turns out that if you add a few descriptors to that "CDC Subset",
 * (Windows) host side drivers from MCCI can treat it as one submode of
 * a proprietary scheme called "SAFE" ... without needing to know about
 * specific product/vendor IDs.  So we do that, making it easier to use
 * those MS-Windows drivers.  Those added descriptors make it resemble a
 * CDC MDLM device, but they don't change device behavior at all.  (See
 * MCCI Engineering report 950198 "SAFE Networking Functions".)
 *
 * A third option is also in use.  Rather than CDC Ethernet, or something
 * simpler, Microsoft pushes their own approach: RNDIS.  The published
 * RNDIS specs are ambiguous and appear to be incomplete, and are also
 * needlessly complex.  They borrow more from CDC ACM than CDC ECM.
 */

#define DRIVER_DESC     "Ethernet Gadget"
#define DRIVER_VERSION      "Memorial Day 2008"

#ifdef USB_ETH_RNDIS
#define PREFIX          "RNDIS/"
#else
#define PREFIX          ""
#endif

/*
 * This driver aims for interoperability by using CDC ECM unless
 *
 *      can_support_ecm()
 *
 * returns false, in which case it supports the CDC Subset.  By default,
 * that returns true; most hardware has no problems with CDC ECM, that's
 * a good default.  Previous versions of this driver had no default; this
 * version changes that, removing overhead for new controller support.
 *
 *  IF YOUR HARDWARE CAN'T SUPPORT CDC ECM, UPDATE THAT ROUTINE!
 */

static inline bool has_rndis(void)
{
#ifdef  USB_ETH_RNDIS
    return true;
#else
    return false;
#endif
}

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

/*
 * Kbuild is not very cooperative with respect to linking separately
 * compiled library objects into one module.  So for now we won't use
 * separate compilation ... ensuring init/exit sections work to shrink
 * the runtime footprint, and giving us at least some parts of what
 * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
 */
#include "f_ecm.c"
#include "f_subset.c"
#ifdef  USB_ETH_RNDIS
#include "f_rndis.c"
#include "rndis.c"
#endif
#include "f_eem.c"
#include "u_ether.c"

/*-------------------------------------------------------------------------*/
USB_GADGET_COMPOSITE_OPTIONS();

/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
 * Instead:  allocate your own, using normal USB-IF procedures.
 */

/* Thanks to NetChip Technologies for donating this product ID.
 * It's for devices with only CDC Ethernet configurations.
 */
#define CDC_VENDOR_NUM      0x0525  /* NetChip */
#define CDC_PRODUCT_NUM     0xa4a1  /* Linux-USB Ethernet Gadget */

/* For hardware that can't talk CDC, we use the same vendor ID that
 * ARM Linux has used for ethernet-over-usb, both with sa1100 and
 * with pxa250.  We're protocol-compatible, if the host-side drivers
 * use the endpoint descriptors.  bcdDevice (version) is nonzero, so
 * drivers that need to hard-wire endpoint numbers have a hook.
 *
 * The protocol is a minimal subset of CDC Ether, which works on any bulk
 * hardware that's not deeply broken ... even on hardware that can't talk
 * RNDIS (like SA-1100, with no interrupt endpoint, or anything that
 * doesn't handle control-OUT).
 */
#define SIMPLE_VENDOR_NUM   0x049f
#define SIMPLE_PRODUCT_NUM  0x505a

/* For hardware that can talk RNDIS and either of the above protocols,
 * use this ID ... the windows INF files will know it.  Unless it's
 * used with CDC Ethernet, Linux 2.4 hosts will need updates to choose
 * the non-RNDIS configuration.
 */
#define RNDIS_VENDOR_NUM    0x0525  /* NetChip */
#define RNDIS_PRODUCT_NUM   0xa4a2  /* Ethernet/RNDIS Gadget */

/* For EEM gadgets */
#define EEM_VENDOR_NUM      0x1d6b  /* Linux Foundation */
#define EEM_PRODUCT_NUM     0x0102  /* EEM Gadget */

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

static struct usb_device_descriptor device_desc = {
    .bLength =      sizeof device_desc,
    .bDescriptorType =  USB_DT_DEVICE,

    .bcdUSB =       cpu_to_le16 (0x0200),

    .bDeviceClass =     USB_CLASS_COMM,
    .bDeviceSubClass =  0,
    .bDeviceProtocol =  0,
    /* .bMaxPacketSize0 = f(hardware) */

    /* Vendor and product id defaults change according to what configs
     * we support.  (As does bNumConfigurations.)  These values can
     * also be overridden by module parameters.
     */
    .idVendor =     cpu_to_le16 (CDC_VENDOR_NUM),
    .idProduct =        cpu_to_le16 (CDC_PRODUCT_NUM),
    /* .bcdDevice = f(hardware) */
    /* .iManufacturer = DYNAMIC */
    /* .iProduct = DYNAMIC */
    /* NO SERIAL NUMBER */
    .bNumConfigurations =   1,
};

static struct usb_otg_descriptor otg_descriptor = {
    .bLength =      sizeof otg_descriptor,
    .bDescriptorType =  USB_DT_OTG,

    /* REVISIT SRP-only hardware is possible, although
     * it would not be called "OTG" ...
     */
    .bmAttributes =     USB_OTG_SRP | USB_OTG_HNP,
};

static const struct usb_descriptor_header *otg_desc[] = {
    (struct usb_descriptor_header *) &otg_descriptor,
    NULL,
};

static struct usb_string strings_dev[] = {
    [USB_GADGET_MANUFACTURER_IDX].s = "",
    [USB_GADGET_PRODUCT_IDX].s = PREFIX DRIVER_DESC,
    [USB_GADGET_SERIAL_IDX].s = "",
    {  } /* end of list */
};

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

static struct usb_gadget_strings *dev_strings[] = {
    &stringtab_dev,
    NULL,
};

static u8 hostaddr[ETH_ALEN];

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

/*
 * We may not have an RNDIS configuration, but if we do it needs to be
 * the first one present.  That's to make Microsoft's drivers happy,
 * and to follow DOCSIS 1.0 (cable modem standard).
 */
static int __init rndis_do_config(struct usb_configuration *c)
{
    /* FIXME alloc iConfiguration string, set it in c->strings */

    if (gadget_is_otg(c->cdev->gadget)) {
        c->descriptors = otg_desc;
        c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
    }

    return rndis_bind_config(c, hostaddr);
}

static struct usb_configuration rndis_config_driver = {
    .label          = "RNDIS",
    .bConfigurationValue    = 2,
    /* .iConfiguration = DYNAMIC */
    .bmAttributes       = USB_CONFIG_ATT_SELFPOWER,
};

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

#ifdef CONFIG_USB_ETH_EEM
static bool use_eem = 1;
#else
static bool use_eem;
#endif
module_param(use_eem, bool, 0);
MODULE_PARM_DESC(use_eem, "use CDC EEM mode");

/*
 * We _always_ have an ECM, CDC Subset, or EEM configuration.
 */
static int __init eth_do_config(struct usb_configuration *c)
{
    /* FIXME alloc iConfiguration string, set it in c->strings */

    if (gadget_is_otg(c->cdev->gadget)) {
        c->descriptors = otg_desc;
        c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
    }

    if (use_eem)
        return eem_bind_config(c);
    else if (can_support_ecm(c->cdev->gadget))
        return ecm_bind_config(c, hostaddr);
    else
        return geth_bind_config(c, hostaddr);
}

static struct usb_configuration eth_config_driver = {
    /* .label = f(hardware) */
    .bConfigurationValue    = 1,
    /* .iConfiguration = DYNAMIC */
    .bmAttributes       = USB_CONFIG_ATT_SELFPOWER,
};

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

static int __init eth_bind(struct usb_composite_dev *cdev)
{
    struct usb_gadget   *gadget = cdev->gadget;
    int         status;

    /* set up network link layer */
    status = gether_setup(cdev->gadget, hostaddr);
    if (status < 0)
        return status;

    /* set up main config label and device descriptor */
    if (use_eem) {
        /* EEM */
        eth_config_driver.label = "CDC Ethernet (EEM)";
        device_desc.idVendor = cpu_to_le16(EEM_VENDOR_NUM);
        device_desc.idProduct = cpu_to_le16(EEM_PRODUCT_NUM);
    } else if (can_support_ecm(cdev->gadget)) {
        /* ECM */
        eth_config_driver.label = "CDC Ethernet (ECM)";
    } else {
        /* CDC Subset */
        eth_config_driver.label = "CDC Subset/SAFE";

        device_desc.idVendor = cpu_to_le16(SIMPLE_VENDOR_NUM);
        device_desc.idProduct = cpu_to_le16(SIMPLE_PRODUCT_NUM);
        if (!has_rndis())
            device_desc.bDeviceClass = USB_CLASS_VENDOR_SPEC;
    }

    if (has_rndis()) {
        /* RNDIS plus ECM-or-Subset */
        device_desc.idVendor = cpu_to_le16(RNDIS_VENDOR_NUM);
        device_desc.idProduct = cpu_to_le16(RNDIS_PRODUCT_NUM);
        device_desc.bNumConfigurations = 2;
    }

    /* Allocate string descriptor numbers ... note that string
     * contents can be overridden by the composite_dev glue.
     */

    status = usb_string_ids_tab(cdev, strings_dev);
    if (status < 0)
        goto fail;
    device_desc.iManufacturer = strings_dev[USB_GADGET_MANUFACTURER_IDX].id;
    device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;

    /* register our configuration(s); RNDIS first, if it's used */
    if (has_rndis()) {
        status = usb_add_config(cdev, &rndis_config_driver,
                rndis_do_config);
        if (status < 0)
            goto fail;
    }

    status = usb_add_config(cdev, &eth_config_driver, eth_do_config);
    if (status < 0)
        goto fail;

    usb_composite_overwrite_options(cdev, &coverwrite);
    dev_info(&gadget->dev, "%s, version: " DRIVER_VERSION "\n",
            DRIVER_DESC);

    return 0;

fail:
    gether_cleanup();
    return status;
}

static int __exit eth_unbind(struct usb_composite_dev *cdev)
{
    gether_cleanup();
    return 0;
}

static __refdata struct usb_composite_driver eth_driver = {
    .name       = "g_ether",
    .dev        = &device_desc,
    .strings    = dev_strings,
    .max_speed  = USB_SPEED_SUPER,
    .bind       = eth_bind,
    .unbind     = __exit_p(eth_unbind),
};

MODULE_DESCRIPTION(PREFIX DRIVER_DESC);
MODULE_AUTHOR("David Brownell, Benedikt Spanger");
MODULE_LICENSE("GPL");

static int __init init(void)
{
    return usb_composite_probe(&eth_driver);
}
module_init(init);

static void __exit cleanup(void)
{
    usb_composite_unregister(&eth_driver);
}
module_exit(cleanup);