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
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/device.h>
  12
  13 #include <linux/ctype.h>
  14 #include <linux/string.h>
  15
  16 #include <linux/usb/ch9.h>
  17 #include <linux/usb/gadget.h>
  18
  19 /**
  20  * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
  21  * descriptor and ep companion descriptor
  22  * @gadget: The device to which the endpoint must belong.
  23  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
  24  *    initialized.  For periodic transfers, the maximum packet
  25  *    size must also be initialized.  This is modified on
  26  *    success.
  27  * @ep_comp: Endpoint companion descriptor, with the required
  28  *    number of streams. Will be modified when the chosen EP
  29  *    supports a different number of streams.
  30  *
  31  * This routine replaces the usb_ep_autoconfig when needed
  32  * superspeed enhancments. If such enhancemnets are required,
  33  * the FD should call usb_ep_autoconfig_ss directly and provide
  34  * the additional ep_comp parameter.
  35  *
  36  * By choosing an endpoint to use with the specified descriptor,
  37  * this routine simplifies writing gadget drivers that work with
  38  * multiple USB device controllers.  The endpoint would be
  39  * passed later to usb_ep_enable(), along with some descriptor.
  40  *
  41  * That second descriptor won't always be the same as the first one.
  42  * For example, isochronous endpoints can be autoconfigured for high
  43  * bandwidth, and then used in several lower bandwidth altsettings.
  44  * Also, high and full speed descriptors will be different.
  45  *
  46  * Be sure to examine and test the results of autoconfiguration
  47  * on your hardware.  This code may not make the best choices
  48  * about how to use the USB controller, and it can't know all
  49  * the restrictions that may apply. Some combinations of driver
  50  * and hardware won't be able to autoconfigure.
  51  *
  52  * On success, this returns an claimed usb_ep, and modifies the endpoint
  53  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
  54  * is initialized as if the endpoint were used at full speed and
  55  * the bmAttribute field in the ep companion descriptor is
  56  * updated with the assigned number of streams if it is
  57  * different from the original value. To prevent the endpoint
  58  * from being returned by a later autoconfig call, claims it by
  59  * assigning ep->claimed to true.
  60  *
  61  * On failure, this returns a null endpoint descriptor.
  62  */
  63 struct usb_ep *usb_ep_autoconfig_ss(
  64         struct usb_gadget               *gadget,
  65         struct usb_endpoint_descriptor  *desc,
  66         struct usb_ss_ep_comp_descriptor *ep_comp
  67 )
  68 {
  69         struct usb_ep   *ep;
  70
  71         if (gadget->ops->match_ep) {
  72                 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
  73                 if (ep)
  74                         goto found_ep;
  75         }
  76
  77         /* Second, look at endpoints until an unclaimed one looks usable */
  78         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
  79                 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
  80                         goto found_ep;
  81         }
  82
  83         /* Fail */
  84         return NULL;
  85 found_ep:
  86
  87         /*
  88          * If the protocol driver hasn't yet decided on wMaxPacketSize
  89          * and wants to know the maximum possible, provide the info.
  90          */
  91         if (desc->wMaxPacketSize == 0)
  92                 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
  93
  94         /* report address */
  95         desc->bEndpointAddress &= USB_DIR_IN;
  96         if (isdigit(ep->name[2])) {
  97                 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
  98                 desc->bEndpointAddress |= num;
  99         } else if (desc->bEndpointAddress & USB_DIR_IN) {
 100                 if (++gadget->in_epnum > 15)
 101                         return NULL;
 102                 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
 103         } else {
 104                 if (++gadget->out_epnum > 15)
 105                         return NULL;
 106                 desc->bEndpointAddress |= gadget->out_epnum;
 107         }
 108
 109         ep->address = desc->bEndpointAddress;
 110         ep->desc = NULL;
 111         ep->comp_desc = NULL;
 112         ep->claimed = true;
 113         return ep;
 114 }
 115 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
 116
 117 /**
 118  * usb_ep_autoconfig() - choose an endpoint matching the
 119  * descriptor
 120  * @gadget: The device to which the endpoint must belong.
 121  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 122  *      initialized.  For periodic transfers, the maximum packet
 123  *      size must also be initialized.  This is modified on success.
 124  *
 125  * By choosing an endpoint to use with the specified descriptor, this
 126  * routine simplifies writing gadget drivers that work with multiple
 127  * USB device controllers.  The endpoint would be passed later to
 128  * usb_ep_enable(), along with some descriptor.
 129  *
 130  * That second descriptor won't always be the same as the first one.
 131  * For example, isochronous endpoints can be autoconfigured for high
 132  * bandwidth, and then used in several lower bandwidth altsettings.
 133  * Also, high and full speed descriptors will be different.
 134  *
 135  * Be sure to examine and test the results of autoconfiguration on your
 136  * hardware.  This code may not make the best choices about how to use the
 137  * USB controller, and it can't know all the restrictions that may apply.
 138  * Some combinations of driver and hardware won't be able to autoconfigure.
 139  *
 140  * On success, this returns an claimed usb_ep, and modifies the endpoint
 141  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 142  * is initialized as if the endpoint were used at full speed. Because of
 143  * that the users must consider adjusting the autoconfigured descriptor.
 144  * To prevent the endpoint from being returned by a later autoconfig call,
 145  * claims it by assigning ep->claimed to true.
 146  *
 147  * On failure, this returns a null endpoint descriptor.
 148  */
 149 struct usb_ep *usb_ep_autoconfig(
 150         struct usb_gadget               *gadget,
 151         struct usb_endpoint_descriptor  *desc
 152 )
 153 {
 154         struct usb_ep   *ep;
 155         u8              type;
 156
 157         ep = usb_ep_autoconfig_ss(gadget, desc, NULL);
 158         if (!ep)
 159                 return NULL;
 160
 161         type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
 162
 163         /* report (variable) full speed bulk maxpacket */
 164         if (type == USB_ENDPOINT_XFER_BULK) {
 165                 int size = ep->maxpacket_limit;
 166
 167                 /* min() doesn't work on bitfields with gcc-3.5 */
 168                 if (size > 64)
 169                         size = 64;
 170                 desc->wMaxPacketSize = cpu_to_le16(size);
 171         }
 172
 173         return ep;
 174 }
 175 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
 176
 177 /**
 178  * usb_ep_autoconfig_release - releases endpoint and set it to initial state
 179  * @ep: endpoint which should be released
 180  *
 181  * This function can be used during function bind for endpoints obtained
 182  * from usb_ep_autoconfig(). It unclaims endpoint claimed by
 183  * usb_ep_autoconfig() to make it available for other functions. Endpoint
 184  * which was released is no longer invalid and shouldn't be used in
 185  * context of function which released it.
 186  */
 187 void usb_ep_autoconfig_release(struct usb_ep *ep)
 188 {
 189         ep->claimed = false;
 190         ep->driver_data = NULL;
 191 }
 192 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
 193
 194 /**
 195  * usb_ep_autoconfig_reset - reset endpoint autoconfig state
 196  * @gadget: device for which autoconfig state will be reset
 197  *
 198  * Use this for devices where one configuration may need to assign
 199  * endpoint resources very differently from the next one.  It clears
 200  * state such as ep->claimed and the record of assigned endpoints
 201  * used by usb_ep_autoconfig().
 202  */
 203 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
 204 {
 205         struct usb_ep   *ep;
 206
 207         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
 208                 ep->claimed = false;
 209                 ep->driver_data = NULL;
 210         }
 211         gadget->in_epnum = 0;
 212         gadget->out_epnum = 0;
 213 }
 214 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);