/*
   * 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>
  #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 =		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,
  	.bcdOTG =		cpu_to_le16(0x0200),
  };
  
  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 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 __init 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 __init 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 __init 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;
  
  	/* 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 fail1;
  	}
  
  	status = usb_add_config(cdev, &eth_config_driver, eth_do_config);
  	if (status < 0)
  		goto fail1;
  
  	usb_composite_overwrite_options(cdev, &coverwrite);
  	dev_info(&gadget->dev, "%s, version: " DRIVER_VERSION "
  ",
  			DRIVER_DESC);
  
  	return 0;
  
  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 __exit 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);
  	}
  	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);
  }
  late_initcall(init);
  
  static void __exit cleanup(void)
  {
  	usb_composite_unregister(&eth_driver);
  }
  module_exit(cleanup);