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// SPDX-License-Identifier: GPL-2.0+
/*
* epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
*
* Copyright (C) 2004 David Brownell
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
/**
* usb_ep_autoconfig_ss() - choose an endpoint matching the ep
* descriptor and ep companion descriptor
* @gadget: The device to which the endpoint must belong.
* @desc: Endpoint descriptor, with endpoint direction and transfer mode
* initialized. For periodic transfers, the maximum packet
* size must also be initialized. This is modified on
* success.
* @ep_comp: Endpoint companion descriptor, with the required
* number of streams. Will be modified when the chosen EP
* supports a different number of streams.
*
* This routine replaces the usb_ep_autoconfig when needed
* superspeed enhancments. If such enhancemnets are required,
* the FD should call usb_ep_autoconfig_ss directly and provide
* the additional ep_comp parameter.
*
* By choosing an endpoint to use with the specified descriptor,
* this routine simplifies writing gadget drivers that work with
* multiple USB device controllers. The endpoint would be
* passed later to usb_ep_enable(), along with some descriptor.
*
* That second descriptor won't always be the same as the first one.
* For example, isochronous endpoints can be autoconfigured for high
* bandwidth, and then used in several lower bandwidth altsettings.
* Also, high and full speed descriptors will be different.
*
* Be sure to examine and test the results of autoconfiguration
* on your hardware. This code may not make the best choices
* about how to use the USB controller, and it can't know all
* the restrictions that may apply. Some combinations of driver
* and hardware won't be able to autoconfigure.
*
* On success, this returns an claimed usb_ep, and modifies the endpoint
* descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
* is initialized as if the endpoint were used at full speed and
* the bmAttribute field in the ep companion descriptor is
* updated with the assigned number of streams if it is
* different from the original value. To prevent the endpoint
* from being returned by a later autoconfig call, claims it by
* assigning ep->claimed to true.
*
* On failure, this returns a null endpoint descriptor.
*/
struct usb_ep *usb_ep_autoconfig_ss(
struct usb_gadget *gadget,
struct usb_endpoint_descriptor *desc,
struct usb_ss_ep_comp_descriptor *ep_comp
)
{
struct usb_ep *ep;
if (gadget->ops->match_ep) {
ep = gadget->ops->match_ep(gadget, desc, ep_comp);
if (ep)
goto found_ep;
}
/* Second, look at endpoints until an unclaimed one looks usable */
list_for_each_entry (ep, &gadget->ep_list, ep_list) {
if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
goto found_ep;
}
/* Fail */
return NULL;
found_ep:
/*
* If the protocol driver hasn't yet decided on wMaxPacketSize
* and wants to know the maximum possible, provide the info.
*/
if (desc->wMaxPacketSize == 0)
desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
/* report address */
desc->bEndpointAddress &= USB_DIR_IN;
if (isdigit(ep->name[2])) {
u8 num = simple_strtoul(&ep->name[2], NULL, 10);
desc->bEndpointAddress |= num;
} else if (desc->bEndpointAddress & USB_DIR_IN) {
if (++gadget->in_epnum > 15)
return NULL;
desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
} else {
if (++gadget->out_epnum > 15)
return NULL;
desc->bEndpointAddress |= gadget->out_epnum;
}
ep->address = desc->bEndpointAddress;
ep->desc = NULL;
ep->comp_desc = NULL;
ep->claimed = true;
return ep;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
/**
* usb_ep_autoconfig() - choose an endpoint matching the
* descriptor
* @gadget: The device to which the endpoint must belong.
* @desc: Endpoint descriptor, with endpoint direction and transfer mode
* initialized. For periodic transfers, the maximum packet
* size must also be initialized. This is modified on success.
*
* By choosing an endpoint to use with the specified descriptor, this
* routine simplifies writing gadget drivers that work with multiple
* USB device controllers. The endpoint would be passed later to
* usb_ep_enable(), along with some descriptor.
*
* That second descriptor won't always be the same as the first one.
* For example, isochronous endpoints can be autoconfigured for high
* bandwidth, and then used in several lower bandwidth altsettings.
* Also, high and full speed descriptors will be different.
*
* Be sure to examine and test the results of autoconfiguration on your
* hardware. This code may not make the best choices about how to use the
* USB controller, and it can't know all the restrictions that may apply.
* Some combinations of driver and hardware won't be able to autoconfigure.
*
* On success, this returns an claimed usb_ep, and modifies the endpoint
* descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
* is initialized as if the endpoint were used at full speed. Because of
* that the users must consider adjusting the autoconfigured descriptor.
* To prevent the endpoint from being returned by a later autoconfig call,
* claims it by assigning ep->claimed to true.
*
* On failure, this returns a null endpoint descriptor.
*/
struct usb_ep *usb_ep_autoconfig(
struct usb_gadget *gadget,
struct usb_endpoint_descriptor *desc
)
{
struct usb_ep *ep;
u8 type;
ep = usb_ep_autoconfig_ss(gadget, desc, NULL);
if (!ep)
return NULL;
type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
/* report (variable) full speed bulk maxpacket */
if (type == USB_ENDPOINT_XFER_BULK) {
int size = ep->maxpacket_limit;
/* min() doesn't work on bitfields with gcc-3.5 */
if (size > 64)
size = 64;
desc->wMaxPacketSize = cpu_to_le16(size);
}
return ep;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
/**
* usb_ep_autoconfig_release - releases endpoint and set it to initial state
* @ep: endpoint which should be released
*
* This function can be used during function bind for endpoints obtained
* from usb_ep_autoconfig(). It unclaims endpoint claimed by
* usb_ep_autoconfig() to make it available for other functions. Endpoint
* which was released is no longer invalid and shouldn't be used in
* context of function which released it.
*/
void usb_ep_autoconfig_release(struct usb_ep *ep)
{
ep->claimed = false;
ep->driver_data = NULL;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
/**
* usb_ep_autoconfig_reset - reset endpoint autoconfig state
* @gadget: device for which autoconfig state will be reset
*
* Use this for devices where one configuration may need to assign
* endpoint resources very differently from the next one. It clears
* state such as ep->claimed and the record of assigned endpoints
* used by usb_ep_autoconfig().
*/
void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
{
struct usb_ep *ep;
list_for_each_entry (ep, &gadget->ep_list, ep_list) {
ep->claimed = false;
ep->driver_data = NULL;
}
gadget->in_epnum = 0;
gadget->out_epnum = 0;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);
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