/*
 * 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];
static struct eth_dev *the_dev;
/*-------------------------------------------------------------------------*/

/*
 * 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, the_dev);
}

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

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 */
        the_dev = gether_setup(cdev->gadget, hostaddr);
        if (IS_ERR(the_dev))
                return PTR_ERR(the_dev);

        /* 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(the_dev);
        return status;
}

static int __exit eth_unbind(struct usb_composite_dev *cdev)
{
        gether_cleanup(the_dev);
        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);