drivers/usb/gadget/epautoconf.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
   4  *
   5  * Copyright (C) 2004 David Brownell
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/device.h>
  17
  18 #include <linux/ctype.h>
  19 #include <linux/string.h>
  20
  21 #include <linux/usb/ch9.h>
  22 #include <linux/usb/gadget.h>
  23
  24 /**
  25  * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
  26  * descriptor and ep companion descriptor
  27  * @gadget: The device to which the endpoint must belong.
  28  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
  29  *    initialized.  For periodic transfers, the maximum packet
  30  *    size must also be initialized.  This is modified on
  31  *    success.
  32  * @ep_comp: Endpoint companion descriptor, with the required
  33  *    number of streams. Will be modified when the chosen EP
  34  *    supports a different number of streams.
  35  *
  36  * This routine replaces the usb_ep_autoconfig when needed
  37  * superspeed enhancments. If such enhancemnets are required,
  38  * the FD should call usb_ep_autoconfig_ss directly and provide
  39  * the additional ep_comp parameter.
  40  *
  41  * By choosing an endpoint to use with the specified descriptor,
  42  * this routine simplifies writing gadget drivers that work with
  43  * multiple USB device controllers.  The endpoint would be
  44  * passed later to usb_ep_enable(), along with some descriptor.
  45  *
  46  * That second descriptor won't always be the same as the first one.
  47  * For example, isochronous endpoints can be autoconfigured for high
  48  * bandwidth, and then used in several lower bandwidth altsettings.
  49  * Also, high and full speed descriptors will be different.
  50  *
  51  * Be sure to examine and test the results of autoconfiguration
  52  * on your hardware.  This code may not make the best choices
  53  * about how to use the USB controller, and it can't know all
  54  * the restrictions that may apply. Some combinations of driver
  55  * and hardware won't be able to autoconfigure.
  56  *
  57  * On success, this returns an claimed usb_ep, and modifies the endpoint
  58  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
  59  * is initialized as if the endpoint were used at full speed and
  60  * the bmAttribute field in the ep companion descriptor is
  61  * updated with the assigned number of streams if it is
  62  * different from the original value. To prevent the endpoint
  63  * from being returned by a later autoconfig call, claims it by
  64  * assigning ep->claimed to true.
  65  *
  66  * On failure, this returns a null endpoint descriptor.
  67  */
  68 struct usb_ep *usb_ep_autoconfig_ss(
  69         struct usb_gadget               *gadget,
  70         struct usb_endpoint_descriptor  *desc,
  71         struct usb_ss_ep_comp_descriptor *ep_comp
  72 )
  73 {
  74         struct usb_ep   *ep;
  75         u8              type;
  76
  77         type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
  78
  79         if (gadget->ops->match_ep) {
  80                 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
  81                 if (ep)
  82                         goto found_ep;
  83         }
  84
  85         /* Second, look at endpoints until an unclaimed one looks usable */
  86         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
  87                 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
  88                         goto found_ep;
  89         }
  90
  91         /* Fail */
  92         return NULL;
  93 found_ep:
  94
  95         /*
  96          * If the protocol driver hasn't yet decided on wMaxPacketSize
  97          * and wants to know the maximum possible, provide the info.
  98          */
  99         if (desc->wMaxPacketSize == 0)
 100                 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
 101
 102         /* report address */
 103         desc->bEndpointAddress &= USB_DIR_IN;
 104         if (isdigit(ep->name[2])) {
 105                 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
 106                 desc->bEndpointAddress |= num;
 107         } else if (desc->bEndpointAddress & USB_DIR_IN) {
 108                 if (++gadget->in_epnum > 15)
 109                         return NULL;
 110                 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
 111         } else {
 112                 if (++gadget->out_epnum > 15)
 113                         return NULL;
 114                 desc->bEndpointAddress |= gadget->out_epnum;
 115         }
 116
 117         /* report (variable) full speed bulk maxpacket */
 118         if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
 119                 int size = ep->maxpacket_limit;
 120
 121                 /* min() doesn't work on bitfields with gcc-3.5 */
 122                 if (size > 64)
 123                         size = 64;
 124                 desc->wMaxPacketSize = cpu_to_le16(size);
 125         }
 126
 127         ep->address = desc->bEndpointAddress;
 128         ep->desc = NULL;
 129         ep->comp_desc = NULL;
 130         ep->claimed = true;
 131         return ep;
 132 }
 133 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
 134
 135 /**
 136  * usb_ep_autoconfig() - choose an endpoint matching the
 137  * descriptor
 138  * @gadget: The device to which the endpoint must belong.
 139  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 140  *      initialized.  For periodic transfers, the maximum packet
 141  *      size must also be initialized.  This is modified on success.
 142  *
 143  * By choosing an endpoint to use with the specified descriptor, this
 144  * routine simplifies writing gadget drivers that work with multiple
 145  * USB device controllers.  The endpoint would be passed later to
 146  * usb_ep_enable(), along with some descriptor.
 147  *
 148  * That second descriptor won't always be the same as the first one.
 149  * For example, isochronous endpoints can be autoconfigured for high
 150  * bandwidth, and then used in several lower bandwidth altsettings.
 151  * Also, high and full speed descriptors will be different.
 152  *
 153  * Be sure to examine and test the results of autoconfiguration on your
 154  * hardware.  This code may not make the best choices about how to use the
 155  * USB controller, and it can't know all the restrictions that may apply.
 156  * Some combinations of driver and hardware won't be able to autoconfigure.
 157  *
 158  * On success, this returns an claimed usb_ep, and modifies the endpoint
 159  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 160  * is initialized as if the endpoint were used at full speed.  To prevent
 161  * the endpoint from being returned by a later autoconfig call, claims it
 162  * by assigning ep->claimed to true.
 163  *
 164  * On failure, this returns a null endpoint descriptor.
 165  */
 166 struct usb_ep *usb_ep_autoconfig(
 167         struct usb_gadget               *gadget,
 168         struct usb_endpoint_descriptor  *desc
 169 )
 170 {
 171         return usb_ep_autoconfig_ss(gadget, desc, NULL);
 172 }
 173 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
 174
 175 /**
 176  * usb_ep_autoconfig_release - releases endpoint and set it to initial state
 177  * @ep: endpoint which should be released
 178  *
 179  * This function can be used during function bind for endpoints obtained
 180  * from usb_ep_autoconfig(). It unclaims endpoint claimed by
 181  * usb_ep_autoconfig() to make it available for other functions. Endpoint
 182  * which was released is no longer invalid and shouldn't be used in
 183  * context of function which released it.
 184  */
 185 void usb_ep_autoconfig_release(struct usb_ep *ep)
 186 {
 187         ep->claimed = false;
 188         ep->driver_data = NULL;
 189 }
 190 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
 191
 192 /**
 193  * usb_ep_autoconfig_reset - reset endpoint autoconfig state
 194  * @gadget: device for which autoconfig state will be reset
 195  *
 196  * Use this for devices where one configuration may need to assign
 197  * endpoint resources very differently from the next one.  It clears
 198  * state such as ep->claimed and the record of assigned endpoints
 199  * used by usb_ep_autoconfig().
 200  */
 201 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
 202 {
 203         struct usb_ep   *ep;
 204
 205         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
 206                 ep->claimed = false;
 207                 ep->driver_data = NULL;
 208         }
 209         gadget->in_epnum = 0;
 210         gadget->out_epnum = 0;
 211 }
 212 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);