Home | History | Annotate | Line # | Download | only in usb
usbdi_util.c revision 1.49.40.1
      1 /*	$NetBSD: usbdi_util.c,v 1.49.40.1 2008/05/16 02:25:12 yamt Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Lennart Augustsson (lennart (at) augustsson.net) at
      9  * Carlstedt Research & Technology.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     30  * POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 __KERNEL_RCSID(0, "$NetBSD: usbdi_util.c,v 1.49.40.1 2008/05/16 02:25:12 yamt Exp $");
     35 
     36 #include <sys/param.h>
     37 #include <sys/systm.h>
     38 #include <sys/kernel.h>
     39 #include <sys/malloc.h>
     40 #if defined(__NetBSD__) || defined(__OpenBSD__)
     41 #include <sys/proc.h>
     42 #include <sys/device.h>
     43 #elif defined(__FreeBSD__)
     44 #include <sys/bus.h>
     45 #endif
     46 
     47 #include <dev/usb/usb.h>
     48 #include <dev/usb/usbhid.h>
     49 
     50 #include <dev/usb/usbdi.h>
     51 #include <dev/usb/usbdi_util.h>
     52 
     53 #ifdef USB_DEBUG
     54 #define DPRINTF(x)	if (usbdebug) logprintf x
     55 #define DPRINTFN(n,x)	if (usbdebug>(n)) logprintf x
     56 extern int usbdebug;
     57 #else
     58 #define DPRINTF(x)
     59 #define DPRINTFN(n,x)
     60 #endif
     61 
     62 usbd_status
     63 usbd_get_desc(usbd_device_handle dev, int type, int index, int len, void *desc)
     64 {
     65 	usb_device_request_t req;
     66 
     67 	DPRINTFN(3,("usbd_get_desc: type=%d, index=%d, len=%d\n",
     68 		    type, index, len));
     69 
     70 	req.bmRequestType = UT_READ_DEVICE;
     71 	req.bRequest = UR_GET_DESCRIPTOR;
     72 	USETW2(req.wValue, type, index);
     73 	USETW(req.wIndex, 0);
     74 	USETW(req.wLength, len);
     75 	return (usbd_do_request(dev, &req, desc));
     76 }
     77 
     78 usbd_status
     79 usbd_get_config_desc(usbd_device_handle dev, int confidx,
     80 		     usb_config_descriptor_t *d)
     81 {
     82 	usbd_status err;
     83 
     84 	DPRINTFN(3,("usbd_get_config_desc: confidx=%d\n", confidx));
     85 	err = usbd_get_desc(dev, UDESC_CONFIG, confidx,
     86 			    USB_CONFIG_DESCRIPTOR_SIZE, d);
     87 	if (err)
     88 		return (err);
     89 	if (d->bDescriptorType != UDESC_CONFIG) {
     90 		DPRINTFN(-1,("usbd_get_config_desc: confidx=%d, bad desc "
     91 			     "len=%d type=%d\n",
     92 			     confidx, d->bLength, d->bDescriptorType));
     93 		return (USBD_INVAL);
     94 	}
     95 	return (USBD_NORMAL_COMPLETION);
     96 }
     97 
     98 usbd_status
     99 usbd_get_config_desc_full(usbd_device_handle dev, int conf, void *d, int size)
    100 {
    101 	DPRINTFN(3,("usbd_get_config_desc_full: conf=%d\n", conf));
    102 	return (usbd_get_desc(dev, UDESC_CONFIG, conf, size, d));
    103 }
    104 
    105 usbd_status
    106 usbd_get_device_desc(usbd_device_handle dev, usb_device_descriptor_t *d)
    107 {
    108 	DPRINTFN(3,("usbd_get_device_desc:\n"));
    109 	return (usbd_get_desc(dev, UDESC_DEVICE,
    110 			     0, USB_DEVICE_DESCRIPTOR_SIZE, d));
    111 }
    112 
    113 usbd_status
    114 usbd_get_device_status(usbd_device_handle dev, usb_status_t *st)
    115 {
    116 	usb_device_request_t req;
    117 
    118 	req.bmRequestType = UT_READ_DEVICE;
    119 	req.bRequest = UR_GET_STATUS;
    120 	USETW(req.wValue, 0);
    121 	USETW(req.wIndex, 0);
    122 	USETW(req.wLength, sizeof(usb_status_t));
    123 	return (usbd_do_request(dev, &req, st));
    124 }
    125 
    126 usbd_status
    127 usbd_get_hub_status(usbd_device_handle dev, usb_hub_status_t *st)
    128 {
    129 	usb_device_request_t req;
    130 
    131 	req.bmRequestType = UT_READ_CLASS_DEVICE;
    132 	req.bRequest = UR_GET_STATUS;
    133 	USETW(req.wValue, 0);
    134 	USETW(req.wIndex, 0);
    135 	USETW(req.wLength, sizeof(usb_hub_status_t));
    136 	return (usbd_do_request(dev, &req, st));
    137 }
    138 
    139 usbd_status
    140 usbd_set_address(usbd_device_handle dev, int addr)
    141 {
    142 	usb_device_request_t req;
    143 
    144 	req.bmRequestType = UT_WRITE_DEVICE;
    145 	req.bRequest = UR_SET_ADDRESS;
    146 	USETW(req.wValue, addr);
    147 	USETW(req.wIndex, 0);
    148 	USETW(req.wLength, 0);
    149 	return usbd_do_request(dev, &req, 0);
    150 }
    151 
    152 usbd_status
    153 usbd_get_port_status(usbd_device_handle dev, int port, usb_port_status_t *ps)
    154 {
    155 	usb_device_request_t req;
    156 
    157 	req.bmRequestType = UT_READ_CLASS_OTHER;
    158 	req.bRequest = UR_GET_STATUS;
    159 	USETW(req.wValue, 0);
    160 	USETW(req.wIndex, port);
    161 	USETW(req.wLength, sizeof *ps);
    162 	return (usbd_do_request(dev, &req, ps));
    163 }
    164 
    165 usbd_status
    166 usbd_clear_hub_feature(usbd_device_handle dev, int sel)
    167 {
    168 	usb_device_request_t req;
    169 
    170 	req.bmRequestType = UT_WRITE_CLASS_DEVICE;
    171 	req.bRequest = UR_CLEAR_FEATURE;
    172 	USETW(req.wValue, sel);
    173 	USETW(req.wIndex, 0);
    174 	USETW(req.wLength, 0);
    175 	return (usbd_do_request(dev, &req, 0));
    176 }
    177 
    178 usbd_status
    179 usbd_set_hub_feature(usbd_device_handle dev, int sel)
    180 {
    181 	usb_device_request_t req;
    182 
    183 	req.bmRequestType = UT_WRITE_CLASS_DEVICE;
    184 	req.bRequest = UR_SET_FEATURE;
    185 	USETW(req.wValue, sel);
    186 	USETW(req.wIndex, 0);
    187 	USETW(req.wLength, 0);
    188 	return (usbd_do_request(dev, &req, 0));
    189 }
    190 
    191 usbd_status
    192 usbd_clear_port_feature(usbd_device_handle dev, int port, int sel)
    193 {
    194 	usb_device_request_t req;
    195 
    196 	req.bmRequestType = UT_WRITE_CLASS_OTHER;
    197 	req.bRequest = UR_CLEAR_FEATURE;
    198 	USETW(req.wValue, sel);
    199 	USETW(req.wIndex, port);
    200 	USETW(req.wLength, 0);
    201 	return (usbd_do_request(dev, &req, 0));
    202 }
    203 
    204 usbd_status
    205 usbd_set_port_feature(usbd_device_handle dev, int port, int sel)
    206 {
    207 	usb_device_request_t req;
    208 
    209 	req.bmRequestType = UT_WRITE_CLASS_OTHER;
    210 	req.bRequest = UR_SET_FEATURE;
    211 	USETW(req.wValue, sel);
    212 	USETW(req.wIndex, port);
    213 	USETW(req.wLength, 0);
    214 	return (usbd_do_request(dev, &req, 0));
    215 }
    216 
    217 usbd_status
    218 usbd_get_protocol(usbd_interface_handle iface, u_int8_t *report)
    219 {
    220 	usb_interface_descriptor_t *id = usbd_get_interface_descriptor(iface);
    221 	usbd_device_handle dev;
    222 	usb_device_request_t req;
    223 
    224 	DPRINTFN(4, ("usbd_get_protocol: iface=%p, endpt=%d\n",
    225 		     iface, id->bInterfaceNumber));
    226 	if (id == NULL)
    227 		return (USBD_IOERROR);
    228 	usbd_interface2device_handle(iface, &dev);
    229 	req.bmRequestType = UT_READ_CLASS_INTERFACE;
    230 	req.bRequest = UR_GET_PROTOCOL;
    231 	USETW(req.wValue, 0);
    232 	USETW(req.wIndex, id->bInterfaceNumber);
    233 	USETW(req.wLength, 1);
    234 	return (usbd_do_request(dev, &req, report));
    235 }
    236 
    237 usbd_status
    238 usbd_set_protocol(usbd_interface_handle iface, int report)
    239 {
    240 	usb_interface_descriptor_t *id = usbd_get_interface_descriptor(iface);
    241 	usbd_device_handle dev;
    242 	usb_device_request_t req;
    243 
    244 	DPRINTFN(4, ("usbd_set_protocol: iface=%p, report=%d, endpt=%d\n",
    245 		     iface, report, id->bInterfaceNumber));
    246 	if (id == NULL)
    247 		return (USBD_IOERROR);
    248 	usbd_interface2device_handle(iface, &dev);
    249 	req.bmRequestType = UT_WRITE_CLASS_INTERFACE;
    250 	req.bRequest = UR_SET_PROTOCOL;
    251 	USETW(req.wValue, report);
    252 	USETW(req.wIndex, id->bInterfaceNumber);
    253 	USETW(req.wLength, 0);
    254 	return (usbd_do_request(dev, &req, 0));
    255 }
    256 
    257 usbd_status
    258 usbd_set_report(usbd_interface_handle iface, int type, int id, void *data,
    259 		int len)
    260 {
    261 	usb_interface_descriptor_t *ifd = usbd_get_interface_descriptor(iface);
    262 	usbd_device_handle dev;
    263 	usb_device_request_t req;
    264 
    265 	DPRINTFN(4, ("usbd_set_report: len=%d\n", len));
    266 	if (ifd == NULL)
    267 		return (USBD_IOERROR);
    268 	usbd_interface2device_handle(iface, &dev);
    269 	req.bmRequestType = UT_WRITE_CLASS_INTERFACE;
    270 	req.bRequest = UR_SET_REPORT;
    271 	USETW2(req.wValue, type, id);
    272 	USETW(req.wIndex, ifd->bInterfaceNumber);
    273 	USETW(req.wLength, len);
    274 	return (usbd_do_request(dev, &req, data));
    275 }
    276 
    277 usbd_status
    278 usbd_set_report_async(usbd_interface_handle iface, int type, int id, void *data,
    279 		      int len)
    280 {
    281 	usb_interface_descriptor_t *ifd = usbd_get_interface_descriptor(iface);
    282 	usbd_device_handle dev;
    283 	usb_device_request_t req;
    284 
    285 	DPRINTFN(4, ("usbd_set_report_async: len=%d\n", len));
    286 	if (ifd == NULL)
    287 		return (USBD_IOERROR);
    288 	usbd_interface2device_handle(iface, &dev);
    289 	req.bmRequestType = UT_WRITE_CLASS_INTERFACE;
    290 	req.bRequest = UR_SET_REPORT;
    291 	USETW2(req.wValue, type, id);
    292 	USETW(req.wIndex, ifd->bInterfaceNumber);
    293 	USETW(req.wLength, len);
    294 	return (usbd_do_request_async(dev, &req, data));
    295 }
    296 
    297 usbd_status
    298 usbd_get_report(usbd_interface_handle iface, int type, int id, void *data,
    299 		int len)
    300 {
    301 	usb_interface_descriptor_t *ifd = usbd_get_interface_descriptor(iface);
    302 	usbd_device_handle dev;
    303 	usb_device_request_t req;
    304 
    305 	DPRINTFN(4, ("usbd_get_report: len=%d\n", len));
    306 	if (ifd == NULL)
    307 		return (USBD_IOERROR);
    308 	usbd_interface2device_handle(iface, &dev);
    309 	req.bmRequestType = UT_READ_CLASS_INTERFACE;
    310 	req.bRequest = UR_GET_REPORT;
    311 	USETW2(req.wValue, type, id);
    312 	USETW(req.wIndex, ifd->bInterfaceNumber);
    313 	USETW(req.wLength, len);
    314 	return (usbd_do_request(dev, &req, data));
    315 }
    316 
    317 usbd_status
    318 usbd_set_idle(usbd_interface_handle iface, int duration, int id)
    319 {
    320 	usb_interface_descriptor_t *ifd = usbd_get_interface_descriptor(iface);
    321 	usbd_device_handle dev;
    322 	usb_device_request_t req;
    323 
    324 	DPRINTFN(4, ("usbd_set_idle: %d %d\n", duration, id));
    325 	if (ifd == NULL)
    326 		return (USBD_IOERROR);
    327 	usbd_interface2device_handle(iface, &dev);
    328 	req.bmRequestType = UT_WRITE_CLASS_INTERFACE;
    329 	req.bRequest = UR_SET_IDLE;
    330 	USETW2(req.wValue, duration, id);
    331 	USETW(req.wIndex, ifd->bInterfaceNumber);
    332 	USETW(req.wLength, 0);
    333 	return (usbd_do_request(dev, &req, 0));
    334 }
    335 
    336 usbd_status
    337 usbd_get_report_descriptor(usbd_device_handle dev, int ifcno,
    338 			   int size, void *d)
    339 {
    340 	usb_device_request_t req;
    341 
    342 	req.bmRequestType = UT_READ_INTERFACE;
    343 	req.bRequest = UR_GET_DESCRIPTOR;
    344 	USETW2(req.wValue, UDESC_REPORT, 0); /* report id should be 0 */
    345 	USETW(req.wIndex, ifcno);
    346 	USETW(req.wLength, size);
    347 	return (usbd_do_request(dev, &req, d));
    348 }
    349 
    350 usb_hid_descriptor_t *
    351 usbd_get_hid_descriptor(usbd_interface_handle ifc)
    352 {
    353 	usb_interface_descriptor_t *idesc = usbd_get_interface_descriptor(ifc);
    354 	usbd_device_handle dev;
    355 	usb_config_descriptor_t *cdesc;
    356 	usb_hid_descriptor_t *hd;
    357 	char *p, *end;
    358 
    359 	if (idesc == NULL)
    360 		return (NULL);
    361 	usbd_interface2device_handle(ifc, &dev);
    362 	cdesc = usbd_get_config_descriptor(dev);
    363 
    364 	p = (char *)idesc + idesc->bLength;
    365 	end = (char *)cdesc + UGETW(cdesc->wTotalLength);
    366 
    367 	for (; p < end; p += hd->bLength) {
    368 		hd = (usb_hid_descriptor_t *)p;
    369 		if (p + hd->bLength <= end && hd->bDescriptorType == UDESC_HID)
    370 			return (hd);
    371 		if (hd->bDescriptorType == UDESC_INTERFACE)
    372 			break;
    373 	}
    374 	return (NULL);
    375 }
    376 
    377 usbd_status
    378 usbd_read_report_desc(usbd_interface_handle ifc, void **descp, int *sizep,
    379 		       usb_malloc_type mem)
    380 {
    381 	usb_interface_descriptor_t *id;
    382 	usb_hid_descriptor_t *hid;
    383 	usbd_device_handle dev;
    384 	usbd_status err;
    385 
    386 	usbd_interface2device_handle(ifc, &dev);
    387 	id = usbd_get_interface_descriptor(ifc);
    388 	if (id == NULL)
    389 		return (USBD_INVAL);
    390 	hid = usbd_get_hid_descriptor(ifc);
    391 	if (hid == NULL)
    392 		return (USBD_IOERROR);
    393 	*sizep = UGETW(hid->descrs[0].wDescriptorLength);
    394 	*descp = malloc(*sizep, mem, M_NOWAIT);
    395 	if (*descp == NULL)
    396 		return (USBD_NOMEM);
    397 	err = usbd_get_report_descriptor(dev, id->bInterfaceNumber,
    398 					 *sizep, *descp);
    399 	if (err) {
    400 		free(*descp, mem);
    401 		*descp = NULL;
    402 		return (err);
    403 	}
    404 	return (USBD_NORMAL_COMPLETION);
    405 }
    406 
    407 usbd_status
    408 usbd_get_config(usbd_device_handle dev, u_int8_t *conf)
    409 {
    410 	usb_device_request_t req;
    411 
    412 	req.bmRequestType = UT_READ_DEVICE;
    413 	req.bRequest = UR_GET_CONFIG;
    414 	USETW(req.wValue, 0);
    415 	USETW(req.wIndex, 0);
    416 	USETW(req.wLength, 1);
    417 	return (usbd_do_request(dev, &req, conf));
    418 }
    419 
    420 Static void usbd_bulk_transfer_cb(usbd_xfer_handle xfer,
    421 				  usbd_private_handle priv, usbd_status status);
    422 Static void
    423 usbd_bulk_transfer_cb(usbd_xfer_handle xfer, usbd_private_handle priv,
    424 		      usbd_status status)
    425 {
    426 	wakeup(xfer);
    427 }
    428 
    429 usbd_status
    430 usbd_bulk_transfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
    431 		   u_int16_t flags, u_int32_t timeout, void *buf,
    432 		   u_int32_t *size, const char *lbl)
    433 {
    434 	usbd_status err;
    435 	int s, error;
    436 
    437 	usbd_setup_xfer(xfer, pipe, 0, buf, *size,
    438 			flags, timeout, usbd_bulk_transfer_cb);
    439 	DPRINTFN(1, ("usbd_bulk_transfer: start transfer %d bytes\n", *size));
    440 	s = splusb();		/* don't want callback until tsleep() */
    441 	err = usbd_transfer(xfer);
    442 	if (err != USBD_IN_PROGRESS) {
    443 		splx(s);
    444 		return (err);
    445 	}
    446 	error = tsleep((void *)xfer, PZERO | PCATCH, lbl, 0);
    447 	splx(s);
    448 	if (error) {
    449 		DPRINTF(("usbd_bulk_transfer: tsleep=%d\n", error));
    450 		usbd_abort_pipe(pipe);
    451 		return (USBD_INTERRUPTED);
    452 	}
    453 	usbd_get_xfer_status(xfer, NULL, NULL, size, &err);
    454 	DPRINTFN(1,("usbd_bulk_transfer: transferred %d\n", *size));
    455 	if (err) {
    456 		DPRINTF(("usbd_bulk_transfer: error=%d\n", err));
    457 		usbd_clear_endpoint_stall(pipe);
    458 	}
    459 	return (err);
    460 }
    461 
    462 Static void usbd_intr_transfer_cb(usbd_xfer_handle xfer,
    463 				  usbd_private_handle priv, usbd_status status);
    464 Static void
    465 usbd_intr_transfer_cb(usbd_xfer_handle xfer, usbd_private_handle priv,
    466 		      usbd_status status)
    467 {
    468 	wakeup(xfer);
    469 }
    470 
    471 usbd_status
    472 usbd_intr_transfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
    473 		   u_int16_t flags, u_int32_t timeout, void *buf,
    474 		   u_int32_t *size, const char *lbl)
    475 {
    476 	usbd_status err;
    477 	int s, error;
    478 
    479 	usbd_setup_xfer(xfer, pipe, 0, buf, *size,
    480 			flags, timeout, usbd_intr_transfer_cb);
    481 	DPRINTFN(1, ("usbd_intr_transfer: start transfer %d bytes\n", *size));
    482 	s = splusb();		/* don't want callback until tsleep() */
    483 	err = usbd_transfer(xfer);
    484 	if (err != USBD_IN_PROGRESS) {
    485 		splx(s);
    486 		return (err);
    487 	}
    488 	error = tsleep(xfer, PZERO | PCATCH, lbl, 0);
    489 	splx(s);
    490 	if (error) {
    491 		DPRINTF(("usbd_intr_transfer: tsleep=%d\n", error));
    492 		usbd_abort_pipe(pipe);
    493 		return (USBD_INTERRUPTED);
    494 	}
    495 	usbd_get_xfer_status(xfer, NULL, NULL, size, &err);
    496 	DPRINTFN(1,("usbd_intr_transfer: transferred %d\n", *size));
    497 	if (err) {
    498 		DPRINTF(("usbd_intr_transfer: error=%d\n", err));
    499 		usbd_clear_endpoint_stall(pipe);
    500 	}
    501 	return (err);
    502 }
    503 
    504 void
    505 usb_detach_wait(device_ptr_t dv)
    506 {
    507 	DPRINTF(("usb_detach_wait: waiting for %s\n", USBDEVPTRNAME(dv)));
    508 	if (tsleep(dv, PZERO, "usbdet", hz * 60))
    509 		printf("usb_detach_wait: %s didn't detach\n",
    510 		        USBDEVPTRNAME(dv));
    511 	DPRINTF(("usb_detach_wait: %s done\n", USBDEVPTRNAME(dv)));
    512 }
    513 
    514 void
    515 usb_detach_wakeup(device_ptr_t dv)
    516 {
    517 	DPRINTF(("usb_detach_wakeup: for %s\n", USBDEVPTRNAME(dv)));
    518 	wakeup(dv);
    519 }
    520 
    521 const usb_cdc_descriptor_t *
    522 usb_find_desc(usbd_device_handle dev, int type, int subtype)
    523 {
    524 	usbd_desc_iter_t iter;
    525 	const usb_cdc_descriptor_t *desc;
    526 
    527 	usb_desc_iter_init(dev, &iter);
    528 	for (;;) {
    529 		desc = (const usb_cdc_descriptor_t *)usb_desc_iter_next(&iter);
    530 		if (!desc || (desc->bDescriptorType == type &&
    531 			      (subtype == USBD_CDCSUBTYPE_ANY ||
    532 			       subtype == desc->bDescriptorSubtype)))
    533 			break;
    534 	}
    535 	return desc;
    536 }
    537 
    538 /* same as usb_find_desc(), but searches only in the specified interface. */
    539 const usb_cdc_descriptor_t *
    540 usb_find_desc_if(usbd_device_handle dev, int type, int subtype,
    541 		 usb_interface_descriptor_t *id)
    542 {
    543 	usbd_desc_iter_t iter;
    544 	const usb_cdc_descriptor_t *desc;
    545 
    546 	usb_desc_iter_init(dev, &iter);
    547 
    548 	iter.cur = (void *)id;		/* start from the interface desc */
    549 	usb_desc_iter_next(&iter);	/* and skip it */
    550 
    551 	while ((desc = (const usb_cdc_descriptor_t *)usb_desc_iter_next(&iter))
    552 	       != NULL) {
    553 		if (desc->bDescriptorType == UDESC_INTERFACE) {
    554 			/* we ran into the next interface --- not found */
    555 			return NULL;
    556 		}
    557 		if (desc->bDescriptorType == type &&
    558 		    (subtype == USBD_CDCSUBTYPE_ANY ||
    559 		     subtype == desc->bDescriptorSubtype))
    560 			break;
    561 	}
    562 	return desc;
    563 }
    564