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         u8              type;
  71
  72         type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
  73
  74         if (gadget->ops->match_ep) {
  75                 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
  76                 if (ep)
  77                         goto found_ep;
  78         }
  79
  80         /* Second, look at endpoints until an unclaimed one looks usable */
  81         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
  82                 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
  83                         goto found_ep;
  84         }
  85
  86         /* Fail */
  87         return NULL;
  88 found_ep:
  89
  90         /*
  91          * If the protocol driver hasn't yet decided on wMaxPacketSize
  92          * and wants to know the maximum possible, provide the info.
  93          */
  94         if (desc->wMaxPacketSize == 0)
  95                 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
  96
  97         /* report address */
  98         desc->bEndpointAddress &= USB_DIR_IN;
  99         if (isdigit(ep->name[2])) {
 100                 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
 101                 desc->bEndpointAddress |= num;
 102         } else if (desc->bEndpointAddress & USB_DIR_IN) {
 103                 if (++gadget->in_epnum > 15)
 104                         return NULL;
 105                 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
 106         } else {
 107                 if (++gadget->out_epnum > 15)
 108                         return NULL;
 109                 desc->bEndpointAddress |= gadget->out_epnum;
 110         }
 111
 112         /* report (variable) full speed bulk maxpacket */
 113         if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
 114                 int size = ep->maxpacket_limit;
 115
 116                 /* min() doesn't work on bitfields with gcc-3.5 */
 117                 if (size > 64)
 118                         size = 64;
 119                 desc->wMaxPacketSize = cpu_to_le16(size);
 120         }
 121
 122         ep->address = desc->bEndpointAddress;
 123         ep->desc = NULL;
 124         ep->comp_desc = NULL;
 125         ep->claimed = true;
 126         return ep;
 127 }
 128 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
 129
 130 /**
 131  * usb_ep_autoconfig() - choose an endpoint matching the
 132  * descriptor
 133  * @gadget: The device to which the endpoint must belong.
 134  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 135  *      initialized.  For periodic transfers, the maximum packet
 136  *      size must also be initialized.  This is modified on success.
 137  *
 138  * By choosing an endpoint to use with the specified descriptor, this
 139  * routine simplifies writing gadget drivers that work with multiple
 140  * USB device controllers.  The endpoint would be passed later to
 141  * usb_ep_enable(), along with some descriptor.
 142  *
 143  * That second descriptor won't always be the same as the first one.
 144  * For example, isochronous endpoints can be autoconfigured for high
 145  * bandwidth, and then used in several lower bandwidth altsettings.
 146  * Also, high and full speed descriptors will be different.
 147  *
 148  * Be sure to examine and test the results of autoconfiguration on your
 149  * hardware.  This code may not make the best choices about how to use the
 150  * USB controller, and it can't know all the restrictions that may apply.
 151  * Some combinations of driver and hardware won't be able to autoconfigure.
 152  *
 153  * On success, this returns an claimed usb_ep, and modifies the endpoint
 154  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 155  * is initialized as if the endpoint were used at full speed.  To prevent
 156  * the endpoint from being returned by a later autoconfig call, claims it
 157  * by assigning ep->claimed to true.
 158  *
 159  * On failure, this returns a null endpoint descriptor.
 160  */
 161 struct usb_ep *usb_ep_autoconfig(
 162         struct usb_gadget               *gadget,
 163         struct usb_endpoint_descriptor  *desc
 164 )
 165 {
 166         return usb_ep_autoconfig_ss(gadget, desc, NULL);
 167 }
 168 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
 169
 170 /**
 171  * usb_ep_autoconfig_release - releases endpoint and set it to initial state
 172  * @ep: endpoint which should be released
 173  *
 174  * This function can be used during function bind for endpoints obtained
 175  * from usb_ep_autoconfig(). It unclaims endpoint claimed by
 176  * usb_ep_autoconfig() to make it available for other functions. Endpoint
 177  * which was released is no longer invalid and shouldn't be used in
 178  * context of function which released it.
 179  */
 180 void usb_ep_autoconfig_release(struct usb_ep *ep)
 181 {
 182         ep->claimed = false;
 183         ep->driver_data = NULL;
 184 }
 185 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
 186
 187 /**
 188  * usb_ep_autoconfig_reset - reset endpoint autoconfig state
 189  * @gadget: device for which autoconfig state will be reset
 190  *
 191  * Use this for devices where one configuration may need to assign
 192  * endpoint resources very differently from the next one.  It clears
 193  * state such as ep->claimed and the record of assigned endpoints
 194  * used by usb_ep_autoconfig().
 195  */
 196 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
 197 {
 198         struct usb_ep   *ep;
 199
 200         list_for_each_entry (ep, &gadget->ep_list, ep_list) {
 201                 ep->claimed = false;
 202                 ep->driver_data = NULL;
 203         }
 204         gadget->in_epnum = 0;
 205         gadget->out_epnum = 0;
 206 }
 207 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);