/*
   * usb/gadget/config.c -- simplify building config descriptors
   *
   * Copyright (C) 2003 David Brownell
   *
   * 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.
   */
  
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/list.h>
  #include <linux/string.h>
  #include <linux/device.h>
  
  #include <linux/usb/ch9.h>
  #include <linux/usb/gadget.h>
  #include <linux/usb/composite.h>
  
  /**
   * usb_descriptor_fillbuf - fill buffer with descriptors
   * @buf: Buffer to be filled
   * @buflen: Size of buf
   * @src: Array of descriptor pointers, terminated by null pointer.
   *
   * Copies descriptors into the buffer, returning the length or a
   * negative error code if they can't all be copied.  Useful when
   * assembling descriptors for an associated set of interfaces used
   * as part of configuring a composite device; or in other cases where
   * sets of descriptors need to be marshaled.
   */
  int
  usb_descriptor_fillbuf(void *buf, unsigned buflen,
  		const struct usb_descriptor_header **src)
  {
  	u8	*dest = buf;
  
  	if (!src)
  		return -EINVAL;
  
  	/* fill buffer from src[] until null descriptor ptr */
  	for (; NULL != *src; src++) {
  		unsigned		len = (*src)->bLength;
  
  		if (len > buflen)
  			return -EINVAL;
  		memcpy(dest, *src, len);
  		buflen -= len;
  		dest += len;
  	}
  	return dest - (u8 *)buf;
  }
  EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);
  
  /**
   * usb_gadget_config_buf - builts a complete configuration descriptor
   * @config: Header for the descriptor, including characteristics such
   *	as power requirements and number of interfaces.
   * @desc: Null-terminated vector of pointers to the descriptors (interface,
   *	endpoint, etc) defining all functions in this device configuration.
   * @buf: Buffer for the resulting configuration descriptor.
   * @length: Length of buffer.  If this is not big enough to hold the
   *	entire configuration descriptor, an error code will be returned.
   *
   * This copies descriptors into the response buffer, building a descriptor
   * for that configuration.  It returns the buffer length or a negative
   * status code.  The config.wTotalLength field is set to match the length
   * of the result, but other descriptor fields (including power usage and
   * interface count) must be set by the caller.
   *
   * Gadget drivers could use this when constructing a config descriptor
   * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
   * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
   */
  int usb_gadget_config_buf(
  	const struct usb_config_descriptor	*config,
  	void					*buf,
  	unsigned				length,
  	const struct usb_descriptor_header	**desc
  )
  {
  	struct usb_config_descriptor		*cp = buf;
  	int					len;
  
  	/* config descriptor first */
  	if (length < USB_DT_CONFIG_SIZE || !desc)
  		return -EINVAL;
  	*cp = *config;
  
  	/* then interface/endpoint/class/vendor/... */
  	len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
  			length - USB_DT_CONFIG_SIZE, desc);
  	if (len < 0)
  		return len;
  	len += USB_DT_CONFIG_SIZE;
  	if (len > 0xffff)
  		return -EINVAL;
  
  	/* patch up the config descriptor */
  	cp->bLength = USB_DT_CONFIG_SIZE;
  	cp->bDescriptorType = USB_DT_CONFIG;
  	cp->wTotalLength = cpu_to_le16(len);
  	cp->bmAttributes |= USB_CONFIG_ATT_ONE;
  	return len;
  }
  EXPORT_SYMBOL_GPL(usb_gadget_config_buf);
  
  /**
   * usb_copy_descriptors - copy a vector of USB descriptors
   * @src: null-terminated vector to copy
   * Context: initialization code, which may sleep
   *
   * This makes a copy of a vector of USB descriptors.  Its primary use
   * is to support usb_function objects which can have multiple copies,
   * each needing different descriptors.  Functions may have static
   * tables of descriptors, which are used as templates and customized
   * with identifiers (for interfaces, strings, endpoints, and more)
   * as needed by a given function instance.
   */
  struct usb_descriptor_header **
  usb_copy_descriptors(struct usb_descriptor_header **src)
  {
  	struct usb_descriptor_header **tmp;
  	unsigned bytes;
  	unsigned n_desc;
  	void *mem;
  	struct usb_descriptor_header **ret;
  
  	/* count descriptors and their sizes; then add vector size */
  	for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
  		bytes += (*tmp)->bLength;
  	bytes += (n_desc + 1) * sizeof(*tmp);
  
  	mem = kmalloc(bytes, GFP_KERNEL);
  	if (!mem)
  		return NULL;
  
  	/* fill in pointers starting at "tmp",
  	 * to descriptors copied starting at "mem";
  	 * and return "ret"
  	 */
  	tmp = mem;
  	ret = mem;
  	mem += (n_desc + 1) * sizeof(*tmp);
  	while (*src) {
  		memcpy(mem, *src, (*src)->bLength);
  		*tmp = mem;
  		tmp++;
  		mem += (*src)->bLength;
  		src++;
  	}
  	*tmp = NULL;
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(usb_copy_descriptors);
  
  int usb_assign_descriptors(struct usb_function *f,
  		struct usb_descriptor_header **fs,
  		struct usb_descriptor_header **hs,
  		struct usb_descriptor_header **ss)
  {
  	struct usb_gadget *g = f->config->cdev->gadget;
  
  	if (fs) {
  		f->fs_descriptors = usb_copy_descriptors(fs);
  		if (!f->fs_descriptors)
  			goto err;
  	}
  	if (hs && gadget_is_dualspeed(g)) {
  		f->hs_descriptors = usb_copy_descriptors(hs);
  		if (!f->hs_descriptors)
  			goto err;
  	}
  	if (ss && gadget_is_superspeed(g)) {
  		f->ss_descriptors = usb_copy_descriptors(ss);
  		if (!f->ss_descriptors)
  			goto err;
  	}
  	return 0;
  err:
  	usb_free_all_descriptors(f);
  	return -ENOMEM;
  }
  EXPORT_SYMBOL_GPL(usb_assign_descriptors);
  
  void usb_free_all_descriptors(struct usb_function *f)
  {
  	usb_free_descriptors(f->fs_descriptors);
  	usb_free_descriptors(f->hs_descriptors);
  	usb_free_descriptors(f->ss_descriptors);
  }
  EXPORT_SYMBOL_GPL(usb_free_all_descriptors);