linux/drivers/usb/gadget/config.c
David Brownell a4c39c41bf usb gadget: descriptor copying support
Define three new descriptor manipulation utilities, for use when
setting up functions that may have multiple instances:

	usb_copy_descriptors() to copy a vector of descriptors
	usb_free_descriptors() to free the copy
	usb_find_endpoint() to find a copied version

These will be used as follows.  Functions will continue to have static
tables of descriptors they update, now used as __initdata templates.

When a function creates a new instance, it patches those tables with
relevant interface and string IDs, plus endpoint assignments.  Then it
copies those morphed descriptors, associates the copies with the new
function instance, and records the endpoint descriptors to use when
activating the endpoints.  When initialization is done, only the copies
remain in memory.  The copies are freed on driver removal.

This ensures that each instance has descriptors which hold the right
instance-specific data.  Two instances in the same configuration will
obviously never share the same interface IDs or use the same endpoints.
Instances in different configurations won't do so either, which means
this is slightly less memory-efficient in some cases.

This also includes a bugfix to the epautoconf code that shows up with
this usage model.  It must replace the previous endpoint number when
updating the template descriptors, not just mask in a few more bits.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 15:16:00 -07:00

192 lines
5.6 KiB
C

/*
* 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 (; NULL != *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;
}
/**
* 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 **__init
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;
}
/**
* usb_find_endpoint - find a copy of an endpoint descriptor
* @src: original vector of descriptors
* @copy: copy of @src
* @ep: endpoint descriptor found in @src
*
* This returns the copy of the @match descriptor made for @copy. Its
* intended use is to help remembering the endpoint descriptor to use
* when enabling a given endpoint.
*/
struct usb_endpoint_descriptor *__init
usb_find_endpoint(
struct usb_descriptor_header **src,
struct usb_descriptor_header **copy,
struct usb_endpoint_descriptor *match
)
{
while (*src) {
if (*src == (void *) match)
return (void *)*copy;
src++;
copy++;
}
return NULL;
}