/* * 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. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include <linux/errno.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/string.h> #include <linux/device.h> #include <linux/usb_ch9.h> #include <linux/usb_gadget.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 (; 0 != *src; src++) { unsigned len = (*src)->bLength; if (len > buflen) return -EINVAL; memcpy(dest, *src, len); buflen -= len; dest += len; } return dest - (u8 *)buf; } /** * 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; }