118 lines
3.7 KiB
C
118 lines
3.7 KiB
C
/*
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* usb/gadget/config.c -- simplify building config descriptors
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*
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* Copyright (C) 2003 David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/string.h>
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#include <linux/device.h>
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#include <linux/usb_ch9.h>
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#include <linux/usb_gadget.h>
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/**
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* usb_descriptor_fillbuf - fill buffer with descriptors
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* @buf: Buffer to be filled
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* @buflen: Size of buf
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* @src: Array of descriptor pointers, terminated by null pointer.
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*
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* Copies descriptors into the buffer, returning the length or a
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* negative error code if they can't all be copied. Useful when
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* assembling descriptors for an associated set of interfaces used
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* as part of configuring a composite device; or in other cases where
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* sets of descriptors need to be marshaled.
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*/
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int
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usb_descriptor_fillbuf(void *buf, unsigned buflen,
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const struct usb_descriptor_header **src)
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{
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u8 *dest = buf;
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if (!src)
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return -EINVAL;
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/* fill buffer from src[] until null descriptor ptr */
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for (; 0 != *src; src++) {
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unsigned len = (*src)->bLength;
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if (len > buflen)
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return -EINVAL;
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memcpy(dest, *src, len);
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buflen -= len;
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dest += len;
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}
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return dest - (u8 *)buf;
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}
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/**
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* usb_gadget_config_buf - builts a complete configuration descriptor
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* @config: Header for the descriptor, including characteristics such
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* as power requirements and number of interfaces.
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* @desc: Null-terminated vector of pointers to the descriptors (interface,
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* endpoint, etc) defining all functions in this device configuration.
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* @buf: Buffer for the resulting configuration descriptor.
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* @length: Length of buffer. If this is not big enough to hold the
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* entire configuration descriptor, an error code will be returned.
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*
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* This copies descriptors into the response buffer, building a descriptor
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* for that configuration. It returns the buffer length or a negative
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* status code. The config.wTotalLength field is set to match the length
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* of the result, but other descriptor fields (including power usage and
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* interface count) must be set by the caller.
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*
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* Gadget drivers could use this when constructing a config descriptor
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* in response to USB_REQ_GET_DESCRIPTOR. They will need to patch the
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* resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
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*/
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int usb_gadget_config_buf(
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const struct usb_config_descriptor *config,
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void *buf,
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unsigned length,
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const struct usb_descriptor_header **desc
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)
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{
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struct usb_config_descriptor *cp = buf;
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int len;
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/* config descriptor first */
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if (length < USB_DT_CONFIG_SIZE || !desc)
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return -EINVAL;
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*cp = *config;
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/* then interface/endpoint/class/vendor/... */
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len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
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length - USB_DT_CONFIG_SIZE, desc);
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if (len < 0)
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return len;
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len += USB_DT_CONFIG_SIZE;
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if (len > 0xffff)
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return -EINVAL;
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/* patch up the config descriptor */
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cp->bLength = USB_DT_CONFIG_SIZE;
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cp->bDescriptorType = USB_DT_CONFIG;
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cp->wTotalLength = cpu_to_le16(len);
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cp->bmAttributes |= USB_CONFIG_ATT_ONE;
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return len;
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}
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