// SPDX-License-Identifier: GPL-2.0+
/*
 * 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
 */

/* #define VERBOSE_DEBUG */

#include <linux/kernel.h>
#include <linux/netdevice.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
}

#include <linux/module.h>

#include "u_ecm.h"
#include "u_gether.h"
#ifdef  USB_ETH_RNDIS
#include "u_rndis.h"
#include "rndis.h"
#else
#define rndis_borrow_net(...) do {} while (0)
#endif
#include "u_eem.h"

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

USB_ETHERNET_MODULE_PARAMETERS();

/* 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 = DYNAMIC */

        .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 const struct usb_descriptor_header *otg_desc[2];

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 struct usb_function_instance *fi_ecm;
static struct usb_function *f_ecm;

static struct usb_function_instance *fi_eem;
static struct usb_function *f_eem;

static struct usb_function_instance *fi_geth;
static struct usb_function *f_geth;

static struct usb_function_instance *fi_rndis;
static struct usb_function *f_rndis;

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

/*
 * 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 rndis_do_config(struct usb_configuration *c)
{
        int status;

        /* 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;
        }

        f_rndis = usb_get_function(fi_rndis);
        if (IS_ERR(f_rndis))
                return PTR_ERR(f_rndis);

        status = usb_add_function(c, f_rndis);
        if (status < 0)
                usb_put_function(f_rndis);

        return status;
}

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 eth_do_config(struct usb_configuration *c)
{
        int status = 0;

        /* 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) {
                f_eem = usb_get_function(fi_eem);
                if (IS_ERR(f_eem))
                        return PTR_ERR(f_eem);

                status = usb_add_function(c, f_eem);
                if (status < 0)
                        usb_put_function(f_eem);

                return status;
        } else if (can_support_ecm(c->cdev->gadget)) {
                f_ecm = usb_get_function(fi_ecm);
                if (IS_ERR(f_ecm))
                        return PTR_ERR(f_ecm);

                status = usb_add_function(c, f_ecm);
                if (status < 0)
                        usb_put_function(f_ecm);

                return status;
        } else {
                f_geth = usb_get_function(fi_geth);
                if (IS_ERR(f_geth))
                        return PTR_ERR(f_geth);

                status = usb_add_function(c, f_geth);
                if (status < 0)
                        usb_put_function(f_geth);

                return status;
        }

}

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

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

static int eth_bind(struct usb_composite_dev *cdev)
{
        struct usb_gadget       *gadget = cdev->gadget;
        struct f_eem_opts       *eem_opts = NULL;
        struct f_ecm_opts       *ecm_opts = NULL;
        struct f_gether_opts    *geth_opts = NULL;
        struct net_device       *net;
        int                     status;

        /* set up main config label and device descriptor */
        if (use_eem) {
                /* EEM */
                fi_eem = usb_get_function_instance("eem");
                if (IS_ERR(fi_eem))
                        return PTR_ERR(fi_eem);

                eem_opts = container_of(fi_eem, struct f_eem_opts, func_inst);

                net = eem_opts->net;

                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(gadget)) {
                /* ECM */

                fi_ecm = usb_get_function_instance("ecm");
                if (IS_ERR(fi_ecm))
                        return PTR_ERR(fi_ecm);

                ecm_opts = container_of(fi_ecm, struct f_ecm_opts, func_inst);

                net = ecm_opts->net;

                eth_config_driver.label = "CDC Ethernet (ECM)";
        } else {
                /* CDC Subset */

                fi_geth = usb_get_function_instance("geth");
                if (IS_ERR(fi_geth))
                        return PTR_ERR(fi_geth);

                geth_opts = container_of(fi_geth, struct f_gether_opts,
                                         func_inst);

                net = geth_opts->net;

                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;
        }

        gether_set_qmult(net, qmult);
        if (!gether_set_host_addr(net, host_addr))
                pr_info("using host ethernet address: %s", host_addr);
        if (!gether_set_dev_addr(net, dev_addr))
                pr_info("using self ethernet address: %s", dev_addr);

        if (has_rndis()) {
                /* RNDIS plus ECM-or-Subset */
                gether_set_gadget(net, cdev->gadget);
                status = gether_register_netdev(net);
                if (status)
                        goto fail;

                if (use_eem)
                        eem_opts->bound = true;
                else if (can_support_ecm(gadget))
                        ecm_opts->bound = true;
                else
                        geth_opts->bound = true;

                fi_rndis = usb_get_function_instance("rndis");
                if (IS_ERR(fi_rndis)) {
                        status = PTR_ERR(fi_rndis);
                        goto fail;
                }

                rndis_borrow_net(fi_rndis, net);

                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 fail1;
        device_desc.iManufacturer = strings_dev[USB_GADGET_MANUFACTURER_IDX].id;
        device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;

        if (gadget_is_otg(gadget) && !otg_desc[0]) {
                struct usb_descriptor_header *usb_desc;

                usb_desc = usb_otg_descriptor_alloc(gadget);
                if (!usb_desc) {
                        status = -ENOMEM;
                        goto fail1;
                }
                usb_otg_descriptor_init(gadget, usb_desc);
                otg_desc[0] = usb_desc;
                otg_desc[1] = NULL;
        }

        /* 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 fail2;
        }

        status = usb_add_config(cdev, &eth_config_driver, eth_do_config);
        if (status < 0)
                goto fail2;

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

        return 0;

fail2:
        kfree(otg_desc[0]);
        otg_desc[0] = NULL;
fail1:
        if (has_rndis())
                usb_put_function_instance(fi_rndis);
fail:
        if (use_eem)
                usb_put_function_instance(fi_eem);
        else if (can_support_ecm(gadget))
                usb_put_function_instance(fi_ecm);
        else
                usb_put_function_instance(fi_geth);
        return status;
}

static int eth_unbind(struct usb_composite_dev *cdev)
{
        if (has_rndis()) {
                usb_put_function(f_rndis);
                usb_put_function_instance(fi_rndis);
        }
        if (use_eem) {
                usb_put_function(f_eem);
                usb_put_function_instance(fi_eem);
        } else if (can_support_ecm(cdev->gadget)) {
                usb_put_function(f_ecm);
                usb_put_function_instance(fi_ecm);
        } else {
                usb_put_function(f_geth);
                usb_put_function_instance(fi_geth);
        }
        kfree(otg_desc[0]);
        otg_desc[0] = NULL;

        return 0;
}

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

module_usb_composite_driver(eth_driver);

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