drivers/usb/gadget/epautoconf.c

   1 /*
   2  * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
   3  *
   4  * Copyright (C) 2004 David Brownell
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/device.h>
  16
  17 #include <linux/ctype.h>
  18 #include <linux/string.h>
  19
  20 #include <linux/usb/ch9.h>
  21 #include <linux/usb/gadget.h>
  22
  23 /**
  24  * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
  25  * descriptor and ep companion descriptor
  26  * @gadget: The device to which the endpoint must belong.
  27  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
  28  *    initialized.  For periodic transfers, the maximum packet
  29  *    size must also be initialized.  This is modified on
  30  *    success.
  31  * @ep_comp: Endpoint companion descriptor, with the required
  32  *    number of streams. Will be modified when the chosen EP
  33  *    supports a different number of streams.
  34  *
  35  * This routine replaces the usb_ep_autoconfig when needed
  36  * superspeed enhancments. If such enhancemnets are required,
  37  * the FD should call usb_ep_autoconfig_ss directly and provide
  38  * the additional ep_comp parameter.
  39  *
  40  * By choosing an endpoint to use with the specified descriptor,
  41  * this routine simplifies writing gadget drivers that work with
  42  * multiple USB device controllers.  The endpoint would be
  43  * passed later to usb_ep_enable(), along with some descriptor.
  44  *
  45  * That second descriptor won't always be the same as the first one.
  46  * For example, isochronous endpoints can be autoconfigured for high
  47  * bandwidth, and then used in several lower bandwidth altsettings.
  48  * Also, high and full speed descriptors will be different.
  49  *
  50  * Be sure to examine and test the results of autoconfiguration
  51  * on your hardware.  This code may not make the best choices
  52  * about how to use the USB controller, and it can't know all
  53  * the restrictions that may apply. Some combinations of driver
  54  * and hardware won't be able to autoconfigure.
  55  *
  56  * On success, this returns an un-claimed usb_ep, and modifies the endpoint
  57  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
  58  * is initialized as if the endpoint were used at full speed and
  59  * the bmAttribute field in the ep companion descriptor is
  60  * updated with the assigned number of streams if it is
  61  * different from the original value. To prevent the endpoint
  62  * from being returned by a later autoconfig call, claim it by
  63  * assigning ep->claimed to true.
  64  *
  65  * On failure, this returns a null endpoint descriptor.
  66  */
  67 struct usb_ep *usb_ep_autoconfig_ss(
  68         struct usb_gadget               *gadget,
  69         struct usb_endpoint_descriptor  *desc,
  70         struct usb_ss_ep_comp_descriptor *ep_comp
  71 )
  72 {
  73         struct usb_ep   *ep;
  74         u8              type;
  75
  76         type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
  77
  78         if (gadget->ops->match_ep) {
  79                 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
  80                 if (ep)
  81                         goto found_ep;
  82         }
  83
  84         /* Second, look at endpoints until an unclaimed one looks usable */
  85         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
  86                 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
  87                         goto found_ep;
  88         }
  89
  90         /* Fail */
  91         return NULL;
  92 found_ep:
  93
  94         /*
  95          * If the protocol driver hasn't yet decided on wMaxPacketSize
  96          * and wants to know the maximum possible, provide the info.
  97          */
  98         if (desc->wMaxPacketSize == 0)
  99                 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
 100
 101         /* report address */
 102         desc->bEndpointAddress &= USB_DIR_IN;
 103         if (isdigit(ep->name[2])) {
 104                 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
 105                 desc->bEndpointAddress |= num;
 106         } else if (desc->bEndpointAddress & USB_DIR_IN) {
 107                 if (++gadget->in_epnum > 15)
 108                         return NULL;
 109                 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
 110         } else {
 111                 if (++gadget->out_epnum > 15)
 112                         return NULL;
 113                 desc->bEndpointAddress |= gadget->out_epnum;
 114         }
 115
 116         /* report (variable) full speed bulk maxpacket */
 117         if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
 118                 int size = ep->maxpacket_limit;
 119
 120                 /* min() doesn't work on bitfields with gcc-3.5 */
 121                 if (size > 64)
 122                         size = 64;
 123                 desc->wMaxPacketSize = cpu_to_le16(size);
 124         }
 125
 126         ep->address = desc->bEndpointAddress;
 127         ep->desc = NULL;
 128         ep->comp_desc = NULL;
 129         ep->claimed = true;
 130         return ep;
 131 }
 132 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
 133
 134 /**
 135  * usb_ep_autoconfig() - choose an endpoint matching the
 136  * descriptor
 137  * @gadget: The device to which the endpoint must belong.
 138  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 139  *      initialized.  For periodic transfers, the maximum packet
 140  *      size must also be initialized.  This is modified on success.
 141  *
 142  * By choosing an endpoint to use with the specified descriptor, this
 143  * routine simplifies writing gadget drivers that work with multiple
 144  * USB device controllers.  The endpoint would be passed later to
 145  * usb_ep_enable(), along with some descriptor.
 146  *
 147  * That second descriptor won't always be the same as the first one.
 148  * For example, isochronous endpoints can be autoconfigured for high
 149  * bandwidth, and then used in several lower bandwidth altsettings.
 150  * Also, high and full speed descriptors will be different.
 151  *
 152  * Be sure to examine and test the results of autoconfiguration on your
 153  * hardware.  This code may not make the best choices about how to use the
 154  * USB controller, and it can't know all the restrictions that may apply.
 155  * Some combinations of driver and hardware won't be able to autoconfigure.
 156  *
 157  * On success, this returns an un-claimed usb_ep, and modifies the endpoint
 158  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 159  * is initialized as if the endpoint were used at full speed.  To prevent
 160  * the endpoint from being returned by a later autoconfig call, claim it
 161  * by assigning ep->claimed to true.
 162  *
 163  * On failure, this returns a null endpoint descriptor.
 164  */
 165 struct usb_ep *usb_ep_autoconfig(
 166         struct usb_gadget               *gadget,
 167         struct usb_endpoint_descriptor  *desc
 168 )
 169 {
 170         return usb_ep_autoconfig_ss(gadget, desc, NULL);
 171 }
 172 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
 173
 174 /**
 175  * usb_ep_autoconfig_reset - reset endpoint autoconfig state
 176  * @gadget: device for which autoconfig state will be reset
 177  *
 178  * Use this for devices where one configuration may need to assign
 179  * endpoint resources very differently from the next one.  It clears
 180  * state such as ep->claimed and the record of assigned endpoints
 181  * used by usb_ep_autoconfig().
 182  */
 183 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
 184 {
 185         struct usb_ep   *ep;
 186
 187         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
 188                 ep->claimed = false;
 189         }
 190         gadget->in_epnum = 0;
 191         gadget->out_epnum = 0;
 192 }
 193 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);