text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * ncm.c -- NCM gadget driver
   *
   * Copyright (C) 2010 Nokia Corporation
   * Contact: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
   *
   * The driver borrows from ether.c which is:
   *
   * Copyright (C) 2003-2005,2008 David Brownell
   * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
   * Copyright (C) 2008 Nokia Corporation
   */
  
  /* #define DEBUG */
  /* #define VERBOSE_DEBUG */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/usb/composite.h>
  
  #include "u_ether.h"
  #include "u_ncm.h"
  
  #define DRIVER_DESC		"NCM Gadget"
  
  /*-------------------------------------------------------------------------*/
  
  /* 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 */
  
  /*-------------------------------------------------------------------------*/
  USB_GADGET_COMPOSITE_OPTIONS();
  
  USB_ETHERNET_MODULE_PARAMETERS();
  
  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];
  
  /* string IDs are assigned dynamically */
  static struct usb_string strings_dev[] = {
  	[USB_GADGET_MANUFACTURER_IDX].s = "",
  	[USB_GADGET_PRODUCT_IDX].s = 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 *f_ncm_inst;
  static struct usb_function *f_ncm;
  
  /*-------------------------------------------------------------------------*/
  
  static int ncm_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_ncm = usb_get_function(f_ncm_inst);
  	if (IS_ERR(f_ncm))
  		return PTR_ERR(f_ncm);
  
  	status = usb_add_function(c, f_ncm);
  	if (status < 0) {
  		usb_put_function(f_ncm);
  		return status;
  	}
  
  	return 0;
  }
  
  static struct usb_configuration ncm_config_driver = {
  	/* .label = f(hardware) */
  	.label			= "CDC Ethernet (NCM)",
  	.bConfigurationValue	= 1,
  	/* .iConfiguration = DYNAMIC */
  	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
  };
  
  /*-------------------------------------------------------------------------*/
  
  static int gncm_bind(struct usb_composite_dev *cdev)
  {
  	struct usb_gadget	*gadget = cdev->gadget;
  	struct f_ncm_opts	*ncm_opts;
  	int			status;
  
  	f_ncm_inst = usb_get_function_instance("ncm");
  	if (IS_ERR(f_ncm_inst))
  		return PTR_ERR(f_ncm_inst);
  
  	ncm_opts = container_of(f_ncm_inst, struct f_ncm_opts, func_inst);
  
  	gether_set_qmult(ncm_opts->net, qmult);
  	if (!gether_set_host_addr(ncm_opts->net, host_addr))
  		pr_info("using host ethernet address: %s", host_addr);
  	if (!gether_set_dev_addr(ncm_opts->net, dev_addr))
  		pr_info("using self ethernet address: %s", dev_addr);
  
  	/* 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;
  
  	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 fail;
  		}
  		usb_otg_descriptor_init(gadget, usb_desc);
  		otg_desc[0] = usb_desc;
  		otg_desc[1] = NULL;
  	}
  
  	status = usb_add_config(cdev, &ncm_config_driver,
  				ncm_do_config);
  	if (status < 0)
  		goto fail1;
  
  	usb_composite_overwrite_options(cdev, &coverwrite);
  	dev_info(&gadget->dev, "%s\n", DRIVER_DESC);
  
  	return 0;
  
  fail1:
  	kfree(otg_desc[0]);
  	otg_desc[0] = NULL;
  fail:
  	usb_put_function_instance(f_ncm_inst);
  	return status;
  }
  
  static int gncm_unbind(struct usb_composite_dev *cdev)
  {
  	if (!IS_ERR_OR_NULL(f_ncm))
  		usb_put_function(f_ncm);
  	if (!IS_ERR_OR_NULL(f_ncm_inst))
  		usb_put_function_instance(f_ncm_inst);
  	kfree(otg_desc[0]);
  	otg_desc[0] = NULL;
  
  	return 0;
  }
  
  static struct usb_composite_driver ncm_driver = {
  	.name		= "g_ncm",
  	.dev		= &device_desc,
  	.strings	= dev_strings,
  	.max_speed	= USB_SPEED_SUPER,
  	.bind		= gncm_bind,
  	.unbind		= gncm_unbind,
  };
  
  module_usb_composite_driver(ncm_driver);
  
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_AUTHOR("Yauheni Kaliuta");
  MODULE_LICENSE("GPL");
  