drivers/usb/gadget/epautoconf.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
  *
  * Copyright (C) 2004 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/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;
 	u8		type;

 	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;

 	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;
 	}

 	/* report (variable) full speed bulk maxpacket */
 	if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
 		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);
 	}

 	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.  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
 )
 {
 	return usb_ep_autoconfig_ss(gadget, desc, NULL);
 }
 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);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
	*
	* Copyright (C) 2004 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/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;
	u8 type;

	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;

	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;
	}

	/* report (variable) full speed bulk maxpacket */
	if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
	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);
	}

	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. 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
	)
	{
	return usb_ep_autoconfig_ss(gadget, desc, NULL);
	}
	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);