usb/gadget/epautoconf.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
0004  *
0005  * Copyright (C) 2004 David Brownell
0006  */
0007
0008 #include <linux/kernel.h>
0009 #include <linux/module.h>
0010 #include <linux/types.h>
0011 #include <linux/device.h>
0012
0013 #include <linux/ctype.h>
0014 #include <linux/string.h>
0015
0016 #include <linux/usb/ch9.h>
0017 #include <linux/usb/gadget.h>
0018
0019 /**
0020  * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
0021  * descriptor and ep companion descriptor
0022  * @gadget: The device to which the endpoint must belong.
0023  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
0024  *    initialized.  For periodic transfers, the maximum packet
0025  *    size must also be initialized.  This is modified on
0026  *    success.
0027  * @ep_comp: Endpoint companion descriptor, with the required
0028  *    number of streams. Will be modified when the chosen EP
0029  *    supports a different number of streams.
0030  *
0031  * This routine replaces the usb_ep_autoconfig when needed
0032  * superspeed enhancments. If such enhancemnets are required,
0033  * the FD should call usb_ep_autoconfig_ss directly and provide
0034  * the additional ep_comp parameter.
0035  *
0036  * By choosing an endpoint to use with the specified descriptor,
0037  * this routine simplifies writing gadget drivers that work with
0038  * multiple USB device controllers.  The endpoint would be
0039  * passed later to usb_ep_enable(), along with some descriptor.
0040  *
0041  * That second descriptor won't always be the same as the first one.
0042  * For example, isochronous endpoints can be autoconfigured for high
0043  * bandwidth, and then used in several lower bandwidth altsettings.
0044  * Also, high and full speed descriptors will be different.
0045  *
0046  * Be sure to examine and test the results of autoconfiguration
0047  * on your hardware.  This code may not make the best choices
0048  * about how to use the USB controller, and it can't know all
0049  * the restrictions that may apply. Some combinations of driver
0050  * and hardware won't be able to autoconfigure.
0051  *
0052  * On success, this returns an claimed usb_ep, and modifies the endpoint
0053  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
0054  * is initialized as if the endpoint were used at full speed and
0055  * the bmAttribute field in the ep companion descriptor is
0056  * updated with the assigned number of streams if it is
0057  * different from the original value. To prevent the endpoint
0058  * from being returned by a later autoconfig call, claims it by
0059  * assigning ep->claimed to true.
0060  *
0061  * On failure, this returns a null endpoint descriptor.
0062  */
0063 struct usb_ep *usb_ep_autoconfig_ss(
0064     struct usb_gadget       *gadget,
0065     struct usb_endpoint_descriptor  *desc,
0066     struct usb_ss_ep_comp_descriptor *ep_comp
0067 )
0068 {
0069     struct usb_ep   *ep;
0070
0071     if (gadget->ops->match_ep) {
0072         ep = gadget->ops->match_ep(gadget, desc, ep_comp);
0073         if (ep)
0074             goto found_ep;
0075     }
0076
0077     /* Second, look at endpoints until an unclaimed one looks usable */
0078     list_for_each_entry (ep, &gadget->ep_list, ep_list) {
0079         if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
0080             goto found_ep;
0081     }
0082
0083     /* Fail */
0084     return NULL;
0085 found_ep:
0086
0087     /*
0088      * If the protocol driver hasn't yet decided on wMaxPacketSize
0089      * and wants to know the maximum possible, provide the info.
0090      */
0091     if (desc->wMaxPacketSize == 0)
0092         desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
0093
0094     /* report address */
0095     desc->bEndpointAddress &= USB_DIR_IN;
0096     if (isdigit(ep->name[2])) {
0097         u8 num = simple_strtoul(&ep->name[2], NULL, 10);
0098         desc->bEndpointAddress |= num;
0099     } else if (desc->bEndpointAddress & USB_DIR_IN) {
0100         if (++gadget->in_epnum > 15)
0101             return NULL;
0102         desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
0103     } else {
0104         if (++gadget->out_epnum > 15)
0105             return NULL;
0106         desc->bEndpointAddress |= gadget->out_epnum;
0107     }
0108
0109     ep->address = desc->bEndpointAddress;
0110     ep->desc = NULL;
0111     ep->comp_desc = NULL;
0112     ep->claimed = true;
0113     return ep;
0114 }
0115 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
0116
0117 /**
0118  * usb_ep_autoconfig() - choose an endpoint matching the
0119  * descriptor
0120  * @gadget: The device to which the endpoint must belong.
0121  * @desc: Endpoint descriptor, with endpoint direction and transfer mode
0122  *  initialized.  For periodic transfers, the maximum packet
0123  *  size must also be initialized.  This is modified on success.
0124  *
0125  * By choosing an endpoint to use with the specified descriptor, this
0126  * routine simplifies writing gadget drivers that work with multiple
0127  * USB device controllers.  The endpoint would be passed later to
0128  * usb_ep_enable(), along with some descriptor.
0129  *
0130  * That second descriptor won't always be the same as the first one.
0131  * For example, isochronous endpoints can be autoconfigured for high
0132  * bandwidth, and then used in several lower bandwidth altsettings.
0133  * Also, high and full speed descriptors will be different.
0134  *
0135  * Be sure to examine and test the results of autoconfiguration on your
0136  * hardware.  This code may not make the best choices about how to use the
0137  * USB controller, and it can't know all the restrictions that may apply.
0138  * Some combinations of driver and hardware won't be able to autoconfigure.
0139  *
0140  * On success, this returns an claimed usb_ep, and modifies the endpoint
0141  * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
0142  * is initialized as if the endpoint were used at full speed. Because of
0143  * that the users must consider adjusting the autoconfigured descriptor.
0144  * To prevent the endpoint from being returned by a later autoconfig call,
0145  * claims it by assigning ep->claimed to true.
0146  *
0147  * On failure, this returns a null endpoint descriptor.
0148  */
0149 struct usb_ep *usb_ep_autoconfig(
0150     struct usb_gadget       *gadget,
0151     struct usb_endpoint_descriptor  *desc
0152 )
0153 {
0154     struct usb_ep   *ep;
0155     u8      type;
0156
0157     ep = usb_ep_autoconfig_ss(gadget, desc, NULL);
0158     if (!ep)
0159         return NULL;
0160
0161     type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
0162
0163     /* report (variable) full speed bulk maxpacket */
0164     if (type == USB_ENDPOINT_XFER_BULK) {
0165         int size = ep->maxpacket_limit;
0166
0167         /* min() doesn't work on bitfields with gcc-3.5 */
0168         if (size > 64)
0169             size = 64;
0170         desc->wMaxPacketSize = cpu_to_le16(size);
0171     }
0172
0173     return ep;
0174 }
0175 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
0176
0177 /**
0178  * usb_ep_autoconfig_release - releases endpoint and set it to initial state
0179  * @ep: endpoint which should be released
0180  *
0181  * This function can be used during function bind for endpoints obtained
0182  * from usb_ep_autoconfig(). It unclaims endpoint claimed by
0183  * usb_ep_autoconfig() to make it available for other functions. Endpoint
0184  * which was released is no longer valid and shouldn't be used in
0185  * context of function which released it.
0186  */
0187 void usb_ep_autoconfig_release(struct usb_ep *ep)
0188 {
0189     ep->claimed = false;
0190     ep->driver_data = NULL;
0191 }
0192 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
0193
0194 /**
0195  * usb_ep_autoconfig_reset - reset endpoint autoconfig state
0196  * @gadget: device for which autoconfig state will be reset
0197  *
0198  * Use this for devices where one configuration may need to assign
0199  * endpoint resources very differently from the next one.  It clears
0200  * state such as ep->claimed and the record of assigned endpoints
0201  * used by usb_ep_autoconfig().
0202  */
0203 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
0204 {
0205     struct usb_ep   *ep;
0206
0207     list_for_each_entry (ep, &gadget->ep_list, ep_list) {
0208         ep->claimed = false;
0209         ep->driver_data = NULL;
0210     }
0211     gadget->in_epnum = 0;
0212     gadget->out_epnum = 0;
0213 }
0214 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);