1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * f_midi.c -- USB MIDI class function driver
4  *
5  * Copyright (C) 2006 Thumtronics Pty Ltd.
6  * Developed for Thumtronics by Grey Innovation
7  * Ben Williamson <ben.williamson@greyinnovation.com>
8  *
9  * Rewritten for the composite framework
10  *   Copyright (C) 2011 Daniel Mack <zonque@gmail.com>
11  *
12  * Based on drivers/usb/gadget/f_audio.c,
13  *   Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
14  *   Copyright (C) 2008 Analog Devices, Inc
15  *
16  * and drivers/usb/gadget/midi.c,
17  *   Copyright (C) 2006 Thumtronics Pty Ltd.
18  *   Ben Williamson <ben.williamson@greyinnovation.com>
19  */
20 
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/slab.h>
24 #include <linux/device.h>
25 #include <linux/kfifo.h>
26 #include <linux/spinlock.h>
27 
28 #include <sound/core.h>
29 #include <sound/initval.h>
30 #include <sound/rawmidi.h>
31 
32 #include <linux/usb/ch9.h>
33 #include <linux/usb/gadget.h>
34 #include <linux/usb/audio.h>
35 #include <linux/usb/midi.h>
36 
37 #include "u_f.h"
38 #include "u_midi.h"
39 
40 MODULE_AUTHOR("Ben Williamson");
41 MODULE_LICENSE("GPL v2");
42 
43 static const char f_midi_shortname[] = "f_midi";
44 static const char f_midi_longname[] = "MIDI Gadget";
45 
46 /*
47  * We can only handle 16 cables on one single endpoint, as cable numbers are
48  * stored in 4-bit fields. And as the interface currently only holds one
49  * single endpoint, this is the maximum number of ports we can allow.
50  */
51 #define MAX_PORTS 16
52 
53 /* MIDI message states */
54 enum {
55 	STATE_INITIAL = 0,	/* pseudo state */
56 	STATE_1PARAM,
57 	STATE_2PARAM_1,
58 	STATE_2PARAM_2,
59 	STATE_SYSEX_0,
60 	STATE_SYSEX_1,
61 	STATE_SYSEX_2,
62 	STATE_REAL_TIME,
63 	STATE_FINISHED,		/* pseudo state */
64 };
65 
66 /*
67  * This is a gadget, and the IN/OUT naming is from the host's perspective.
68  * USB -> OUT endpoint -> rawmidi
69  * USB <- IN endpoint  <- rawmidi
70  */
71 struct gmidi_in_port {
72 	struct snd_rawmidi_substream *substream;
73 	int active;
74 	uint8_t cable;
75 	uint8_t state;
76 	uint8_t data[2];
77 };
78 
79 struct f_midi {
80 	struct usb_function	func;
81 	struct usb_gadget	*gadget;
82 	struct usb_ep		*in_ep, *out_ep;
83 	struct snd_card		*card;
84 	struct snd_rawmidi	*rmidi;
85 	u8			ms_id;
86 
87 	struct snd_rawmidi_substream *out_substream[MAX_PORTS];
88 
89 	unsigned long		out_triggered;
90 	struct work_struct	work;
91 	unsigned int in_ports;
92 	unsigned int out_ports;
93 	int index;
94 	char *id;
95 	unsigned int buflen, qlen;
96 	/* This fifo is used as a buffer ring for pre-allocated IN usb_requests */
97 	DECLARE_KFIFO_PTR(in_req_fifo, struct usb_request *);
98 	spinlock_t transmit_lock;
99 	unsigned int in_last_port;
100 	unsigned char free_ref;
101 
102 	struct gmidi_in_port	in_ports_array[/* in_ports */];
103 };
104 
105 static inline struct f_midi *func_to_midi(struct usb_function *f)
106 {
107 	return container_of(f, struct f_midi, func);
108 }
109 
110 static void f_midi_transmit(struct f_midi *midi);
111 static void f_midi_rmidi_free(struct snd_rawmidi *rmidi);
112 static void f_midi_free_inst(struct usb_function_instance *f);
113 
114 DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
115 DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
116 DECLARE_USB_MS_ENDPOINT_DESCRIPTOR(16);
117 
118 /* B.3.1  Standard AC Interface Descriptor */
119 static struct usb_interface_descriptor ac_interface_desc = {
120 	.bLength =		USB_DT_INTERFACE_SIZE,
121 	.bDescriptorType =	USB_DT_INTERFACE,
122 	/* .bInterfaceNumber =	DYNAMIC */
123 	/* .bNumEndpoints =	DYNAMIC */
124 	.bInterfaceClass =	USB_CLASS_AUDIO,
125 	.bInterfaceSubClass =	USB_SUBCLASS_AUDIOCONTROL,
126 	/* .iInterface =	DYNAMIC */
127 };
128 
129 /* B.3.2  Class-Specific AC Interface Descriptor */
130 static struct uac1_ac_header_descriptor_1 ac_header_desc = {
131 	.bLength =		UAC_DT_AC_HEADER_SIZE(1),
132 	.bDescriptorType =	USB_DT_CS_INTERFACE,
133 	.bDescriptorSubtype =	USB_MS_HEADER,
134 	.bcdADC =		cpu_to_le16(0x0100),
135 	.wTotalLength =		cpu_to_le16(UAC_DT_AC_HEADER_SIZE(1)),
136 	.bInCollection =	1,
137 	/* .baInterfaceNr =	DYNAMIC */
138 };
139 
140 /* B.4.1  Standard MS Interface Descriptor */
141 static struct usb_interface_descriptor ms_interface_desc = {
142 	.bLength =		USB_DT_INTERFACE_SIZE,
143 	.bDescriptorType =	USB_DT_INTERFACE,
144 	/* .bInterfaceNumber =	DYNAMIC */
145 	.bNumEndpoints =	2,
146 	.bInterfaceClass =	USB_CLASS_AUDIO,
147 	.bInterfaceSubClass =	USB_SUBCLASS_MIDISTREAMING,
148 	/* .iInterface =	DYNAMIC */
149 };
150 
151 /* B.4.2  Class-Specific MS Interface Descriptor */
152 static struct usb_ms_header_descriptor ms_header_desc = {
153 	.bLength =		USB_DT_MS_HEADER_SIZE,
154 	.bDescriptorType =	USB_DT_CS_INTERFACE,
155 	.bDescriptorSubtype =	USB_MS_HEADER,
156 	.bcdMSC =		cpu_to_le16(0x0100),
157 	/* .wTotalLength =	DYNAMIC */
158 };
159 
160 /* B.5.1  Standard Bulk OUT Endpoint Descriptor */
161 static struct usb_endpoint_descriptor bulk_out_desc = {
162 	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
163 	.bDescriptorType =	USB_DT_ENDPOINT,
164 	.bEndpointAddress =	USB_DIR_OUT,
165 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
166 };
167 
168 static struct usb_ss_ep_comp_descriptor bulk_out_ss_comp_desc = {
169 	.bLength                = sizeof(bulk_out_ss_comp_desc),
170 	.bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
171 	/* .bMaxBurst           = 0, */
172 	/* .bmAttributes        = 0, */
173 };
174 
175 /* B.5.2  Class-specific MS Bulk OUT Endpoint Descriptor */
176 static struct usb_ms_endpoint_descriptor_16 ms_out_desc = {
177 	/* .bLength =		DYNAMIC */
178 	.bDescriptorType =	USB_DT_CS_ENDPOINT,
179 	.bDescriptorSubtype =	USB_MS_GENERAL,
180 	/* .bNumEmbMIDIJack =	DYNAMIC */
181 	/* .baAssocJackID =	DYNAMIC */
182 };
183 
184 /* B.6.1  Standard Bulk IN Endpoint Descriptor */
185 static struct usb_endpoint_descriptor bulk_in_desc = {
186 	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
187 	.bDescriptorType =	USB_DT_ENDPOINT,
188 	.bEndpointAddress =	USB_DIR_IN,
189 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
190 };
191 
192 static struct usb_ss_ep_comp_descriptor bulk_in_ss_comp_desc = {
193 	.bLength                = sizeof(bulk_in_ss_comp_desc),
194 	.bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
195 	/* .bMaxBurst           = 0, */
196 	/* .bmAttributes        = 0, */
197 };
198 
199 /* B.6.2  Class-specific MS Bulk IN Endpoint Descriptor */
200 static struct usb_ms_endpoint_descriptor_16 ms_in_desc = {
201 	/* .bLength =		DYNAMIC */
202 	.bDescriptorType =	USB_DT_CS_ENDPOINT,
203 	.bDescriptorSubtype =	USB_MS_GENERAL,
204 	/* .bNumEmbMIDIJack =	DYNAMIC */
205 	/* .baAssocJackID =	DYNAMIC */
206 };
207 
208 /* string IDs are assigned dynamically */
209 
210 #define STRING_FUNC_IDX			0
211 
212 static struct usb_string midi_string_defs[] = {
213 	[STRING_FUNC_IDX].s = "MIDI function",
214 	{  } /* end of list */
215 };
216 
217 static struct usb_gadget_strings midi_stringtab = {
218 	.language	= 0x0409,	/* en-us */
219 	.strings	= midi_string_defs,
220 };
221 
222 static struct usb_gadget_strings *midi_strings[] = {
223 	&midi_stringtab,
224 	NULL,
225 };
226 
227 static inline struct usb_request *midi_alloc_ep_req(struct usb_ep *ep,
228 						    unsigned length)
229 {
230 	return alloc_ep_req(ep, length);
231 }
232 
233 static const uint8_t f_midi_cin_length[] = {
234 	0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
235 };
236 
237 /*
238  * Receives a chunk of MIDI data.
239  */
240 static void f_midi_read_data(struct usb_ep *ep, int cable,
241 			     uint8_t *data, int length)
242 {
243 	struct f_midi *midi = ep->driver_data;
244 	struct snd_rawmidi_substream *substream = midi->out_substream[cable];
245 
246 	if (!substream)
247 		/* Nobody is listening - throw it on the floor. */
248 		return;
249 
250 	if (!test_bit(cable, &midi->out_triggered))
251 		return;
252 
253 	snd_rawmidi_receive(substream, data, length);
254 }
255 
256 static void f_midi_handle_out_data(struct usb_ep *ep, struct usb_request *req)
257 {
258 	unsigned int i;
259 	u8 *buf = req->buf;
260 
261 	for (i = 0; i + 3 < req->actual; i += 4)
262 		if (buf[i] != 0) {
263 			int cable = buf[i] >> 4;
264 			int length = f_midi_cin_length[buf[i] & 0x0f];
265 			f_midi_read_data(ep, cable, &buf[i + 1], length);
266 		}
267 }
268 
269 static void
270 f_midi_complete(struct usb_ep *ep, struct usb_request *req)
271 {
272 	struct f_midi *midi = ep->driver_data;
273 	struct usb_composite_dev *cdev = midi->func.config->cdev;
274 	int status = req->status;
275 
276 	switch (status) {
277 	case 0:			 /* normal completion */
278 		if (ep == midi->out_ep) {
279 			/* We received stuff. req is queued again, below */
280 			f_midi_handle_out_data(ep, req);
281 		} else if (ep == midi->in_ep) {
282 			/* Our transmit completed. See if there's more to go.
283 			 * f_midi_transmit eats req, don't queue it again. */
284 			req->length = 0;
285 			f_midi_transmit(midi);
286 			return;
287 		}
288 		break;
289 
290 	/* this endpoint is normally active while we're configured */
291 	case -ECONNABORTED:	/* hardware forced ep reset */
292 	case -ECONNRESET:	/* request dequeued */
293 	case -ESHUTDOWN:	/* disconnect from host */
294 		VDBG(cdev, "%s gone (%d), %d/%d\n", ep->name, status,
295 				req->actual, req->length);
296 		if (ep == midi->out_ep) {
297 			f_midi_handle_out_data(ep, req);
298 			/* We don't need to free IN requests because it's handled
299 			 * by the midi->in_req_fifo. */
300 			free_ep_req(ep, req);
301 		}
302 		return;
303 
304 	case -EOVERFLOW:	/* buffer overrun on read means that
305 				 * we didn't provide a big enough buffer.
306 				 */
307 	default:
308 		DBG(cdev, "%s complete --> %d, %d/%d\n", ep->name,
309 				status, req->actual, req->length);
310 		break;
311 	case -EREMOTEIO:	/* short read */
312 		break;
313 	}
314 
315 	status = usb_ep_queue(ep, req, GFP_ATOMIC);
316 	if (status) {
317 		ERROR(cdev, "kill %s:  resubmit %d bytes --> %d\n",
318 				ep->name, req->length, status);
319 		usb_ep_set_halt(ep);
320 		/* FIXME recover later ... somehow */
321 	}
322 }
323 
324 static void f_midi_drop_out_substreams(struct f_midi *midi)
325 {
326 	unsigned int i;
327 
328 	for (i = 0; i < midi->in_ports; i++) {
329 		struct gmidi_in_port *port = midi->in_ports_array + i;
330 		struct snd_rawmidi_substream *substream = port->substream;
331 
332 		if (port->active && substream)
333 			snd_rawmidi_drop_output(substream);
334 	}
335 }
336 
337 static int f_midi_start_ep(struct f_midi *midi,
338 			   struct usb_function *f,
339 			   struct usb_ep *ep)
340 {
341 	int err;
342 	struct usb_composite_dev *cdev = f->config->cdev;
343 
344 	usb_ep_disable(ep);
345 
346 	err = config_ep_by_speed(midi->gadget, f, ep);
347 	if (err) {
348 		ERROR(cdev, "can't configure %s: %d\n", ep->name, err);
349 		return err;
350 	}
351 
352 	err = usb_ep_enable(ep);
353 	if (err) {
354 		ERROR(cdev, "can't start %s: %d\n", ep->name, err);
355 		return err;
356 	}
357 
358 	ep->driver_data = midi;
359 
360 	return 0;
361 }
362 
363 static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
364 {
365 	struct f_midi *midi = func_to_midi(f);
366 	unsigned i;
367 	int err;
368 
369 	/* we only set alt for MIDIStreaming interface */
370 	if (intf != midi->ms_id)
371 		return 0;
372 
373 	err = f_midi_start_ep(midi, f, midi->in_ep);
374 	if (err)
375 		return err;
376 
377 	err = f_midi_start_ep(midi, f, midi->out_ep);
378 	if (err)
379 		return err;
380 
381 	/* pre-allocate write usb requests to use on f_midi_transmit. */
382 	while (kfifo_avail(&midi->in_req_fifo)) {
383 		struct usb_request *req =
384 			midi_alloc_ep_req(midi->in_ep, midi->buflen);
385 
386 		if (req == NULL)
387 			return -ENOMEM;
388 
389 		req->length = 0;
390 		req->complete = f_midi_complete;
391 
392 		kfifo_put(&midi->in_req_fifo, req);
393 	}
394 
395 	/* allocate a bunch of read buffers and queue them all at once. */
396 	for (i = 0; i < midi->qlen && err == 0; i++) {
397 		struct usb_request *req =
398 			midi_alloc_ep_req(midi->out_ep, midi->buflen);
399 
400 		if (req == NULL)
401 			return -ENOMEM;
402 
403 		req->complete = f_midi_complete;
404 		err = usb_ep_queue(midi->out_ep, req, GFP_ATOMIC);
405 		if (err) {
406 			ERROR(midi, "%s: couldn't enqueue request: %d\n",
407 				    midi->out_ep->name, err);
408 			if (req->buf != NULL)
409 				free_ep_req(midi->out_ep, req);
410 			return err;
411 		}
412 	}
413 
414 	return 0;
415 }
416 
417 static void f_midi_disable(struct usb_function *f)
418 {
419 	struct f_midi *midi = func_to_midi(f);
420 	struct usb_composite_dev *cdev = f->config->cdev;
421 	struct usb_request *req = NULL;
422 
423 	DBG(cdev, "disable\n");
424 
425 	/*
426 	 * just disable endpoints, forcing completion of pending i/o.
427 	 * all our completion handlers free their requests in this case.
428 	 */
429 	usb_ep_disable(midi->in_ep);
430 	usb_ep_disable(midi->out_ep);
431 
432 	/* release IN requests */
433 	while (kfifo_get(&midi->in_req_fifo, &req))
434 		free_ep_req(midi->in_ep, req);
435 
436 	f_midi_drop_out_substreams(midi);
437 }
438 
439 static int f_midi_snd_free(struct snd_device *device)
440 {
441 	return 0;
442 }
443 
444 /*
445  * Converts MIDI commands to USB MIDI packets.
446  */
447 static void f_midi_transmit_byte(struct usb_request *req,
448 				 struct gmidi_in_port *port, uint8_t b)
449 {
450 	uint8_t p[4] = { port->cable << 4, 0, 0, 0 };
451 	uint8_t next_state = STATE_INITIAL;
452 
453 	switch (b) {
454 	case 0xf8 ... 0xff:
455 		/* System Real-Time Messages */
456 		p[0] |= 0x0f;
457 		p[1] = b;
458 		next_state = port->state;
459 		port->state = STATE_REAL_TIME;
460 		break;
461 
462 	case 0xf7:
463 		/* End of SysEx */
464 		switch (port->state) {
465 		case STATE_SYSEX_0:
466 			p[0] |= 0x05;
467 			p[1] = 0xf7;
468 			next_state = STATE_FINISHED;
469 			break;
470 		case STATE_SYSEX_1:
471 			p[0] |= 0x06;
472 			p[1] = port->data[0];
473 			p[2] = 0xf7;
474 			next_state = STATE_FINISHED;
475 			break;
476 		case STATE_SYSEX_2:
477 			p[0] |= 0x07;
478 			p[1] = port->data[0];
479 			p[2] = port->data[1];
480 			p[3] = 0xf7;
481 			next_state = STATE_FINISHED;
482 			break;
483 		default:
484 			/* Ignore byte */
485 			next_state = port->state;
486 			port->state = STATE_INITIAL;
487 		}
488 		break;
489 
490 	case 0xf0 ... 0xf6:
491 		/* System Common Messages */
492 		port->data[0] = port->data[1] = 0;
493 		port->state = STATE_INITIAL;
494 		switch (b) {
495 		case 0xf0:
496 			port->data[0] = b;
497 			port->data[1] = 0;
498 			next_state = STATE_SYSEX_1;
499 			break;
500 		case 0xf1:
501 		case 0xf3:
502 			port->data[0] = b;
503 			next_state = STATE_1PARAM;
504 			break;
505 		case 0xf2:
506 			port->data[0] = b;
507 			next_state = STATE_2PARAM_1;
508 			break;
509 		case 0xf4:
510 		case 0xf5:
511 			next_state = STATE_INITIAL;
512 			break;
513 		case 0xf6:
514 			p[0] |= 0x05;
515 			p[1] = 0xf6;
516 			next_state = STATE_FINISHED;
517 			break;
518 		}
519 		break;
520 
521 	case 0x80 ... 0xef:
522 		/*
523 		 * Channel Voice Messages, Channel Mode Messages
524 		 * and Control Change Messages.
525 		 */
526 		port->data[0] = b;
527 		port->data[1] = 0;
528 		port->state = STATE_INITIAL;
529 		if (b >= 0xc0 && b <= 0xdf)
530 			next_state = STATE_1PARAM;
531 		else
532 			next_state = STATE_2PARAM_1;
533 		break;
534 
535 	case 0x00 ... 0x7f:
536 		/* Message parameters */
537 		switch (port->state) {
538 		case STATE_1PARAM:
539 			if (port->data[0] < 0xf0)
540 				p[0] |= port->data[0] >> 4;
541 			else
542 				p[0] |= 0x02;
543 
544 			p[1] = port->data[0];
545 			p[2] = b;
546 			/* This is to allow Running State Messages */
547 			next_state = STATE_1PARAM;
548 			break;
549 		case STATE_2PARAM_1:
550 			port->data[1] = b;
551 			next_state = STATE_2PARAM_2;
552 			break;
553 		case STATE_2PARAM_2:
554 			if (port->data[0] < 0xf0)
555 				p[0] |= port->data[0] >> 4;
556 			else
557 				p[0] |= 0x03;
558 
559 			p[1] = port->data[0];
560 			p[2] = port->data[1];
561 			p[3] = b;
562 			/* This is to allow Running State Messages */
563 			next_state = STATE_2PARAM_1;
564 			break;
565 		case STATE_SYSEX_0:
566 			port->data[0] = b;
567 			next_state = STATE_SYSEX_1;
568 			break;
569 		case STATE_SYSEX_1:
570 			port->data[1] = b;
571 			next_state = STATE_SYSEX_2;
572 			break;
573 		case STATE_SYSEX_2:
574 			p[0] |= 0x04;
575 			p[1] = port->data[0];
576 			p[2] = port->data[1];
577 			p[3] = b;
578 			next_state = STATE_SYSEX_0;
579 			break;
580 		}
581 		break;
582 	}
583 
584 	/* States where we have to write into the USB request */
585 	if (next_state == STATE_FINISHED ||
586 	    port->state == STATE_SYSEX_2 ||
587 	    port->state == STATE_1PARAM ||
588 	    port->state == STATE_2PARAM_2 ||
589 	    port->state == STATE_REAL_TIME) {
590 
591 		unsigned int length = req->length;
592 		u8 *buf = (u8 *)req->buf + length;
593 
594 		memcpy(buf, p, sizeof(p));
595 		req->length = length + sizeof(p);
596 
597 		if (next_state == STATE_FINISHED) {
598 			next_state = STATE_INITIAL;
599 			port->data[0] = port->data[1] = 0;
600 		}
601 	}
602 
603 	port->state = next_state;
604 }
605 
606 static int f_midi_do_transmit(struct f_midi *midi, struct usb_ep *ep)
607 {
608 	struct usb_request *req = NULL;
609 	unsigned int len, i;
610 	bool active = false;
611 	int err;
612 
613 	/*
614 	 * We peek the request in order to reuse it if it fails to enqueue on
615 	 * its endpoint
616 	 */
617 	len = kfifo_peek(&midi->in_req_fifo, &req);
618 	if (len != 1) {
619 		ERROR(midi, "%s: Couldn't get usb request\n", __func__);
620 		return -1;
621 	}
622 
623 	/*
624 	 * If buffer overrun, then we ignore this transmission.
625 	 * IMPORTANT: This will cause the user-space rawmidi device to block
626 	 * until a) usb requests have been completed or b) snd_rawmidi_write()
627 	 * times out.
628 	 */
629 	if (req->length > 0)
630 		return 0;
631 
632 	for (i = midi->in_last_port; i < midi->in_ports; ++i) {
633 		struct gmidi_in_port *port = midi->in_ports_array + i;
634 		struct snd_rawmidi_substream *substream = port->substream;
635 
636 		if (!port->active || !substream)
637 			continue;
638 
639 		while (req->length + 3 < midi->buflen) {
640 			uint8_t b;
641 
642 			if (snd_rawmidi_transmit(substream, &b, 1) != 1) {
643 				port->active = 0;
644 				break;
645 			}
646 			f_midi_transmit_byte(req, port, b);
647 		}
648 
649 		active = !!port->active;
650 		if (active)
651 			break;
652 	}
653 	midi->in_last_port = active ? i : 0;
654 
655 	if (req->length <= 0)
656 		goto done;
657 
658 	err = usb_ep_queue(ep, req, GFP_ATOMIC);
659 	if (err < 0) {
660 		ERROR(midi, "%s failed to queue req: %d\n",
661 		      midi->in_ep->name, err);
662 		req->length = 0; /* Re-use request next time. */
663 	} else {
664 		/* Upon success, put request at the back of the queue. */
665 		kfifo_skip(&midi->in_req_fifo);
666 		kfifo_put(&midi->in_req_fifo, req);
667 	}
668 
669 done:
670 	return active;
671 }
672 
673 static void f_midi_transmit(struct f_midi *midi)
674 {
675 	struct usb_ep *ep = midi->in_ep;
676 	int ret;
677 	unsigned long flags;
678 
679 	/* We only care about USB requests if IN endpoint is enabled */
680 	if (!ep || !ep->enabled)
681 		goto drop_out;
682 
683 	spin_lock_irqsave(&midi->transmit_lock, flags);
684 
685 	do {
686 		ret = f_midi_do_transmit(midi, ep);
687 		if (ret < 0) {
688 			spin_unlock_irqrestore(&midi->transmit_lock, flags);
689 			goto drop_out;
690 		}
691 	} while (ret);
692 
693 	spin_unlock_irqrestore(&midi->transmit_lock, flags);
694 
695 	return;
696 
697 drop_out:
698 	f_midi_drop_out_substreams(midi);
699 }
700 
701 static void f_midi_in_work(struct work_struct *work)
702 {
703 	struct f_midi *midi;
704 
705 	midi = container_of(work, struct f_midi, work);
706 	f_midi_transmit(midi);
707 }
708 
709 static int f_midi_in_open(struct snd_rawmidi_substream *substream)
710 {
711 	struct f_midi *midi = substream->rmidi->private_data;
712 	struct gmidi_in_port *port;
713 
714 	if (substream->number >= midi->in_ports)
715 		return -EINVAL;
716 
717 	VDBG(midi, "%s()\n", __func__);
718 	port = midi->in_ports_array + substream->number;
719 	port->substream = substream;
720 	port->state = STATE_INITIAL;
721 	return 0;
722 }
723 
724 static int f_midi_in_close(struct snd_rawmidi_substream *substream)
725 {
726 	struct f_midi *midi = substream->rmidi->private_data;
727 
728 	VDBG(midi, "%s()\n", __func__);
729 	return 0;
730 }
731 
732 static void f_midi_in_trigger(struct snd_rawmidi_substream *substream, int up)
733 {
734 	struct f_midi *midi = substream->rmidi->private_data;
735 
736 	if (substream->number >= midi->in_ports)
737 		return;
738 
739 	VDBG(midi, "%s() %d\n", __func__, up);
740 	midi->in_ports_array[substream->number].active = up;
741 	if (up)
742 		queue_work(system_highpri_wq, &midi->work);
743 }
744 
745 static int f_midi_out_open(struct snd_rawmidi_substream *substream)
746 {
747 	struct f_midi *midi = substream->rmidi->private_data;
748 
749 	if (substream->number >= MAX_PORTS)
750 		return -EINVAL;
751 
752 	VDBG(midi, "%s()\n", __func__);
753 	midi->out_substream[substream->number] = substream;
754 	return 0;
755 }
756 
757 static int f_midi_out_close(struct snd_rawmidi_substream *substream)
758 {
759 	struct f_midi *midi = substream->rmidi->private_data;
760 
761 	VDBG(midi, "%s()\n", __func__);
762 	return 0;
763 }
764 
765 static void f_midi_out_trigger(struct snd_rawmidi_substream *substream, int up)
766 {
767 	struct f_midi *midi = substream->rmidi->private_data;
768 
769 	VDBG(midi, "%s()\n", __func__);
770 
771 	if (up)
772 		set_bit(substream->number, &midi->out_triggered);
773 	else
774 		clear_bit(substream->number, &midi->out_triggered);
775 }
776 
777 static const struct snd_rawmidi_ops gmidi_in_ops = {
778 	.open = f_midi_in_open,
779 	.close = f_midi_in_close,
780 	.trigger = f_midi_in_trigger,
781 };
782 
783 static const struct snd_rawmidi_ops gmidi_out_ops = {
784 	.open = f_midi_out_open,
785 	.close = f_midi_out_close,
786 	.trigger = f_midi_out_trigger
787 };
788 
789 static inline void f_midi_unregister_card(struct f_midi *midi)
790 {
791 	if (midi->card) {
792 		snd_card_free(midi->card);
793 		midi->card = NULL;
794 	}
795 }
796 
797 /* register as a sound "card" */
798 static int f_midi_register_card(struct f_midi *midi)
799 {
800 	struct snd_card *card;
801 	struct snd_rawmidi *rmidi;
802 	int err;
803 	static struct snd_device_ops ops = {
804 		.dev_free = f_midi_snd_free,
805 	};
806 
807 	err = snd_card_new(&midi->gadget->dev, midi->index, midi->id,
808 			   THIS_MODULE, 0, &card);
809 	if (err < 0) {
810 		ERROR(midi, "snd_card_new() failed\n");
811 		goto fail;
812 	}
813 	midi->card = card;
814 
815 	err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, midi, &ops);
816 	if (err < 0) {
817 		ERROR(midi, "snd_device_new() failed: error %d\n", err);
818 		goto fail;
819 	}
820 
821 	strcpy(card->driver, f_midi_longname);
822 	strcpy(card->longname, f_midi_longname);
823 	strcpy(card->shortname, f_midi_shortname);
824 
825 	/* Set up rawmidi */
826 	snd_component_add(card, "MIDI");
827 	err = snd_rawmidi_new(card, card->longname, 0,
828 			      midi->out_ports, midi->in_ports, &rmidi);
829 	if (err < 0) {
830 		ERROR(midi, "snd_rawmidi_new() failed: error %d\n", err);
831 		goto fail;
832 	}
833 	midi->rmidi = rmidi;
834 	midi->in_last_port = 0;
835 	strcpy(rmidi->name, card->shortname);
836 	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
837 			    SNDRV_RAWMIDI_INFO_INPUT |
838 			    SNDRV_RAWMIDI_INFO_DUPLEX;
839 	rmidi->private_data = midi;
840 	rmidi->private_free = f_midi_rmidi_free;
841 	midi->free_ref++;
842 
843 	/*
844 	 * Yes, rawmidi OUTPUT = USB IN, and rawmidi INPUT = USB OUT.
845 	 * It's an upside-down world being a gadget.
846 	 */
847 	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &gmidi_in_ops);
848 	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &gmidi_out_ops);
849 
850 	/* register it - we're ready to go */
851 	err = snd_card_register(card);
852 	if (err < 0) {
853 		ERROR(midi, "snd_card_register() failed\n");
854 		goto fail;
855 	}
856 
857 	VDBG(midi, "%s() finished ok\n", __func__);
858 	return 0;
859 
860 fail:
861 	f_midi_unregister_card(midi);
862 	return err;
863 }
864 
865 /* MIDI function driver setup/binding */
866 
867 static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
868 {
869 	struct usb_descriptor_header **midi_function;
870 	struct usb_midi_in_jack_descriptor jack_in_ext_desc[MAX_PORTS];
871 	struct usb_midi_in_jack_descriptor jack_in_emb_desc[MAX_PORTS];
872 	struct usb_midi_out_jack_descriptor_1 jack_out_ext_desc[MAX_PORTS];
873 	struct usb_midi_out_jack_descriptor_1 jack_out_emb_desc[MAX_PORTS];
874 	struct usb_composite_dev *cdev = c->cdev;
875 	struct f_midi *midi = func_to_midi(f);
876 	struct usb_string *us;
877 	int status, n, jack = 1, i = 0, endpoint_descriptor_index = 0;
878 
879 	midi->gadget = cdev->gadget;
880 	INIT_WORK(&midi->work, f_midi_in_work);
881 	status = f_midi_register_card(midi);
882 	if (status < 0)
883 		goto fail_register;
884 
885 	/* maybe allocate device-global string ID */
886 	us = usb_gstrings_attach(c->cdev, midi_strings,
887 				 ARRAY_SIZE(midi_string_defs));
888 	if (IS_ERR(us)) {
889 		status = PTR_ERR(us);
890 		goto fail;
891 	}
892 	ac_interface_desc.iInterface = us[STRING_FUNC_IDX].id;
893 
894 	/* We have two interfaces, AudioControl and MIDIStreaming */
895 	status = usb_interface_id(c, f);
896 	if (status < 0)
897 		goto fail;
898 	ac_interface_desc.bInterfaceNumber = status;
899 
900 	status = usb_interface_id(c, f);
901 	if (status < 0)
902 		goto fail;
903 	ms_interface_desc.bInterfaceNumber = status;
904 	ac_header_desc.baInterfaceNr[0] = status;
905 	midi->ms_id = status;
906 
907 	status = -ENODEV;
908 
909 	/* allocate instance-specific endpoints */
910 	midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
911 	if (!midi->in_ep)
912 		goto fail;
913 
914 	midi->out_ep = usb_ep_autoconfig(cdev->gadget, &bulk_out_desc);
915 	if (!midi->out_ep)
916 		goto fail;
917 
918 	/* allocate temporary function list */
919 	midi_function = kcalloc((MAX_PORTS * 4) + 11, sizeof(*midi_function),
920 				GFP_KERNEL);
921 	if (!midi_function) {
922 		status = -ENOMEM;
923 		goto fail;
924 	}
925 
926 	/*
927 	 * construct the function's descriptor set. As the number of
928 	 * input and output MIDI ports is configurable, we have to do
929 	 * it that way.
930 	 */
931 
932 	/* add the headers - these are always the same */
933 	midi_function[i++] = (struct usb_descriptor_header *) &ac_interface_desc;
934 	midi_function[i++] = (struct usb_descriptor_header *) &ac_header_desc;
935 	midi_function[i++] = (struct usb_descriptor_header *) &ms_interface_desc;
936 
937 	/* calculate the header's wTotalLength */
938 	n = USB_DT_MS_HEADER_SIZE
939 		+ (midi->in_ports + midi->out_ports) *
940 			(USB_DT_MIDI_IN_SIZE + USB_DT_MIDI_OUT_SIZE(1));
941 	ms_header_desc.wTotalLength = cpu_to_le16(n);
942 
943 	midi_function[i++] = (struct usb_descriptor_header *) &ms_header_desc;
944 
945 	/* configure the external IN jacks, each linked to an embedded OUT jack */
946 	for (n = 0; n < midi->in_ports; n++) {
947 		struct usb_midi_in_jack_descriptor *in_ext = &jack_in_ext_desc[n];
948 		struct usb_midi_out_jack_descriptor_1 *out_emb = &jack_out_emb_desc[n];
949 
950 		in_ext->bLength			= USB_DT_MIDI_IN_SIZE;
951 		in_ext->bDescriptorType		= USB_DT_CS_INTERFACE;
952 		in_ext->bDescriptorSubtype	= USB_MS_MIDI_IN_JACK;
953 		in_ext->bJackType		= USB_MS_EXTERNAL;
954 		in_ext->bJackID			= jack++;
955 		in_ext->iJack			= 0;
956 		midi_function[i++] = (struct usb_descriptor_header *) in_ext;
957 
958 		out_emb->bLength		= USB_DT_MIDI_OUT_SIZE(1);
959 		out_emb->bDescriptorType	= USB_DT_CS_INTERFACE;
960 		out_emb->bDescriptorSubtype	= USB_MS_MIDI_OUT_JACK;
961 		out_emb->bJackType		= USB_MS_EMBEDDED;
962 		out_emb->bJackID		= jack++;
963 		out_emb->bNrInputPins		= 1;
964 		out_emb->pins[0].baSourcePin	= 1;
965 		out_emb->pins[0].baSourceID	= in_ext->bJackID;
966 		out_emb->iJack			= 0;
967 		midi_function[i++] = (struct usb_descriptor_header *) out_emb;
968 
969 		/* link it to the endpoint */
970 		ms_in_desc.baAssocJackID[n] = out_emb->bJackID;
971 	}
972 
973 	/* configure the external OUT jacks, each linked to an embedded IN jack */
974 	for (n = 0; n < midi->out_ports; n++) {
975 		struct usb_midi_in_jack_descriptor *in_emb = &jack_in_emb_desc[n];
976 		struct usb_midi_out_jack_descriptor_1 *out_ext = &jack_out_ext_desc[n];
977 
978 		in_emb->bLength			= USB_DT_MIDI_IN_SIZE;
979 		in_emb->bDescriptorType		= USB_DT_CS_INTERFACE;
980 		in_emb->bDescriptorSubtype	= USB_MS_MIDI_IN_JACK;
981 		in_emb->bJackType		= USB_MS_EMBEDDED;
982 		in_emb->bJackID			= jack++;
983 		in_emb->iJack			= 0;
984 		midi_function[i++] = (struct usb_descriptor_header *) in_emb;
985 
986 		out_ext->bLength =		USB_DT_MIDI_OUT_SIZE(1);
987 		out_ext->bDescriptorType =	USB_DT_CS_INTERFACE;
988 		out_ext->bDescriptorSubtype =	USB_MS_MIDI_OUT_JACK;
989 		out_ext->bJackType =		USB_MS_EXTERNAL;
990 		out_ext->bJackID =		jack++;
991 		out_ext->bNrInputPins =		1;
992 		out_ext->iJack =		0;
993 		out_ext->pins[0].baSourceID =	in_emb->bJackID;
994 		out_ext->pins[0].baSourcePin =	1;
995 		midi_function[i++] = (struct usb_descriptor_header *) out_ext;
996 
997 		/* link it to the endpoint */
998 		ms_out_desc.baAssocJackID[n] = in_emb->bJackID;
999 	}
1000 
1001 	/* configure the endpoint descriptors ... */
1002 	ms_out_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->in_ports);
1003 	ms_out_desc.bNumEmbMIDIJack = midi->in_ports;
1004 
1005 	ms_in_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->out_ports);
1006 	ms_in_desc.bNumEmbMIDIJack = midi->out_ports;
1007 
1008 	/* ... and add them to the list */
1009 	endpoint_descriptor_index = i;
1010 	midi_function[i++] = (struct usb_descriptor_header *) &bulk_out_desc;
1011 	midi_function[i++] = (struct usb_descriptor_header *) &ms_out_desc;
1012 	midi_function[i++] = (struct usb_descriptor_header *) &bulk_in_desc;
1013 	midi_function[i++] = (struct usb_descriptor_header *) &ms_in_desc;
1014 	midi_function[i++] = NULL;
1015 
1016 	/*
1017 	 * support all relevant hardware speeds... we expect that when
1018 	 * hardware is dual speed, all bulk-capable endpoints work at
1019 	 * both speeds
1020 	 */
1021 	/* copy descriptors, and track endpoint copies */
1022 	f->fs_descriptors = usb_copy_descriptors(midi_function);
1023 	if (!f->fs_descriptors)
1024 		goto fail_f_midi;
1025 
1026 	if (gadget_is_dualspeed(c->cdev->gadget)) {
1027 		bulk_in_desc.wMaxPacketSize = cpu_to_le16(512);
1028 		bulk_out_desc.wMaxPacketSize = cpu_to_le16(512);
1029 		f->hs_descriptors = usb_copy_descriptors(midi_function);
1030 		if (!f->hs_descriptors)
1031 			goto fail_f_midi;
1032 	}
1033 
1034 	if (gadget_is_superspeed(c->cdev->gadget)) {
1035 		bulk_in_desc.wMaxPacketSize = cpu_to_le16(1024);
1036 		bulk_out_desc.wMaxPacketSize = cpu_to_le16(1024);
1037 		i = endpoint_descriptor_index;
1038 		midi_function[i++] = (struct usb_descriptor_header *)
1039 				     &bulk_out_desc;
1040 		midi_function[i++] = (struct usb_descriptor_header *)
1041 				     &bulk_out_ss_comp_desc;
1042 		midi_function[i++] = (struct usb_descriptor_header *)
1043 				     &ms_out_desc;
1044 		midi_function[i++] = (struct usb_descriptor_header *)
1045 				     &bulk_in_desc;
1046 		midi_function[i++] = (struct usb_descriptor_header *)
1047 				     &bulk_in_ss_comp_desc;
1048 		midi_function[i++] = (struct usb_descriptor_header *)
1049 				     &ms_in_desc;
1050 		f->ss_descriptors = usb_copy_descriptors(midi_function);
1051 		if (!f->ss_descriptors)
1052 			goto fail_f_midi;
1053 
1054 		if (gadget_is_superspeed_plus(c->cdev->gadget)) {
1055 			f->ssp_descriptors = usb_copy_descriptors(midi_function);
1056 			if (!f->ssp_descriptors)
1057 				goto fail_f_midi;
1058 		}
1059 	}
1060 
1061 	kfree(midi_function);
1062 
1063 	return 0;
1064 
1065 fail_f_midi:
1066 	kfree(midi_function);
1067 	usb_free_all_descriptors(f);
1068 fail:
1069 	f_midi_unregister_card(midi);
1070 fail_register:
1071 	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
1072 
1073 	return status;
1074 }
1075 
1076 static inline struct f_midi_opts *to_f_midi_opts(struct config_item *item)
1077 {
1078 	return container_of(to_config_group(item), struct f_midi_opts,
1079 			    func_inst.group);
1080 }
1081 
1082 static void midi_attr_release(struct config_item *item)
1083 {
1084 	struct f_midi_opts *opts = to_f_midi_opts(item);
1085 
1086 	usb_put_function_instance(&opts->func_inst);
1087 }
1088 
1089 static struct configfs_item_operations midi_item_ops = {
1090 	.release	= midi_attr_release,
1091 };
1092 
1093 #define F_MIDI_OPT(name, test_limit, limit)				\
1094 static ssize_t f_midi_opts_##name##_show(struct config_item *item, char *page) \
1095 {									\
1096 	struct f_midi_opts *opts = to_f_midi_opts(item);		\
1097 	int result;							\
1098 									\
1099 	mutex_lock(&opts->lock);					\
1100 	result = sprintf(page, "%u\n", opts->name);			\
1101 	mutex_unlock(&opts->lock);					\
1102 									\
1103 	return result;							\
1104 }									\
1105 									\
1106 static ssize_t f_midi_opts_##name##_store(struct config_item *item,	\
1107 					 const char *page, size_t len)	\
1108 {									\
1109 	struct f_midi_opts *opts = to_f_midi_opts(item);		\
1110 	int ret;							\
1111 	u32 num;							\
1112 									\
1113 	mutex_lock(&opts->lock);					\
1114 	if (opts->refcnt > 1) {						\
1115 		ret = -EBUSY;						\
1116 		goto end;						\
1117 	}								\
1118 									\
1119 	ret = kstrtou32(page, 0, &num);					\
1120 	if (ret)							\
1121 		goto end;						\
1122 									\
1123 	if (test_limit && num > limit) {				\
1124 		ret = -EINVAL;						\
1125 		goto end;						\
1126 	}								\
1127 	opts->name = num;						\
1128 	ret = len;							\
1129 									\
1130 end:									\
1131 	mutex_unlock(&opts->lock);					\
1132 	return ret;							\
1133 }									\
1134 									\
1135 CONFIGFS_ATTR(f_midi_opts_, name);
1136 
1137 #define F_MIDI_OPT_SIGNED(name, test_limit, limit)				\
1138 static ssize_t f_midi_opts_##name##_show(struct config_item *item, char *page) \
1139 {									\
1140 	struct f_midi_opts *opts = to_f_midi_opts(item);		\
1141 	int result;							\
1142 									\
1143 	mutex_lock(&opts->lock);					\
1144 	result = sprintf(page, "%d\n", opts->name);			\
1145 	mutex_unlock(&opts->lock);					\
1146 									\
1147 	return result;							\
1148 }									\
1149 									\
1150 static ssize_t f_midi_opts_##name##_store(struct config_item *item,	\
1151 					 const char *page, size_t len)	\
1152 {									\
1153 	struct f_midi_opts *opts = to_f_midi_opts(item);		\
1154 	int ret;							\
1155 	s32 num;							\
1156 									\
1157 	mutex_lock(&opts->lock);					\
1158 	if (opts->refcnt > 1) {						\
1159 		ret = -EBUSY;						\
1160 		goto end;						\
1161 	}								\
1162 									\
1163 	ret = kstrtos32(page, 0, &num);					\
1164 	if (ret)							\
1165 		goto end;						\
1166 									\
1167 	if (test_limit && num > limit) {				\
1168 		ret = -EINVAL;						\
1169 		goto end;						\
1170 	}								\
1171 	opts->name = num;						\
1172 	ret = len;							\
1173 									\
1174 end:									\
1175 	mutex_unlock(&opts->lock);					\
1176 	return ret;							\
1177 }									\
1178 									\
1179 CONFIGFS_ATTR(f_midi_opts_, name);
1180 
1181 F_MIDI_OPT_SIGNED(index, true, SNDRV_CARDS);
1182 F_MIDI_OPT(buflen, false, 0);
1183 F_MIDI_OPT(qlen, false, 0);
1184 F_MIDI_OPT(in_ports, true, MAX_PORTS);
1185 F_MIDI_OPT(out_ports, true, MAX_PORTS);
1186 
1187 static ssize_t f_midi_opts_id_show(struct config_item *item, char *page)
1188 {
1189 	struct f_midi_opts *opts = to_f_midi_opts(item);
1190 	int result;
1191 
1192 	mutex_lock(&opts->lock);
1193 	if (opts->id) {
1194 		result = strlcpy(page, opts->id, PAGE_SIZE);
1195 	} else {
1196 		page[0] = 0;
1197 		result = 0;
1198 	}
1199 
1200 	mutex_unlock(&opts->lock);
1201 
1202 	return result;
1203 }
1204 
1205 static ssize_t f_midi_opts_id_store(struct config_item *item,
1206 				    const char *page, size_t len)
1207 {
1208 	struct f_midi_opts *opts = to_f_midi_opts(item);
1209 	int ret;
1210 	char *c;
1211 
1212 	mutex_lock(&opts->lock);
1213 	if (opts->refcnt > 1) {
1214 		ret = -EBUSY;
1215 		goto end;
1216 	}
1217 
1218 	c = kstrndup(page, len, GFP_KERNEL);
1219 	if (!c) {
1220 		ret = -ENOMEM;
1221 		goto end;
1222 	}
1223 	if (opts->id_allocated)
1224 		kfree(opts->id);
1225 	opts->id = c;
1226 	opts->id_allocated = true;
1227 	ret = len;
1228 end:
1229 	mutex_unlock(&opts->lock);
1230 	return ret;
1231 }
1232 
1233 CONFIGFS_ATTR(f_midi_opts_, id);
1234 
1235 static struct configfs_attribute *midi_attrs[] = {
1236 	&f_midi_opts_attr_index,
1237 	&f_midi_opts_attr_buflen,
1238 	&f_midi_opts_attr_qlen,
1239 	&f_midi_opts_attr_in_ports,
1240 	&f_midi_opts_attr_out_ports,
1241 	&f_midi_opts_attr_id,
1242 	NULL,
1243 };
1244 
1245 static const struct config_item_type midi_func_type = {
1246 	.ct_item_ops	= &midi_item_ops,
1247 	.ct_attrs	= midi_attrs,
1248 	.ct_owner	= THIS_MODULE,
1249 };
1250 
1251 static void f_midi_free_inst(struct usb_function_instance *f)
1252 {
1253 	struct f_midi_opts *opts;
1254 	bool free = false;
1255 
1256 	opts = container_of(f, struct f_midi_opts, func_inst);
1257 
1258 	mutex_lock(&opts->lock);
1259 	if (!--opts->refcnt) {
1260 		free = true;
1261 	}
1262 	mutex_unlock(&opts->lock);
1263 
1264 	if (free) {
1265 		if (opts->id_allocated)
1266 			kfree(opts->id);
1267 		kfree(opts);
1268 	}
1269 }
1270 
1271 static struct usb_function_instance *f_midi_alloc_inst(void)
1272 {
1273 	struct f_midi_opts *opts;
1274 
1275 	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
1276 	if (!opts)
1277 		return ERR_PTR(-ENOMEM);
1278 
1279 	mutex_init(&opts->lock);
1280 	opts->func_inst.free_func_inst = f_midi_free_inst;
1281 	opts->index = SNDRV_DEFAULT_IDX1;
1282 	opts->id = SNDRV_DEFAULT_STR1;
1283 	opts->buflen = 512;
1284 	opts->qlen = 32;
1285 	opts->in_ports = 1;
1286 	opts->out_ports = 1;
1287 	opts->refcnt = 1;
1288 
1289 	config_group_init_type_name(&opts->func_inst.group, "",
1290 				    &midi_func_type);
1291 
1292 	return &opts->func_inst;
1293 }
1294 
1295 static void f_midi_free(struct usb_function *f)
1296 {
1297 	struct f_midi *midi;
1298 	struct f_midi_opts *opts;
1299 	bool free = false;
1300 
1301 	midi = func_to_midi(f);
1302 	opts = container_of(f->fi, struct f_midi_opts, func_inst);
1303 	mutex_lock(&opts->lock);
1304 	if (!--midi->free_ref) {
1305 		kfree(midi->id);
1306 		kfifo_free(&midi->in_req_fifo);
1307 		kfree(midi);
1308 		free = true;
1309 	}
1310 	mutex_unlock(&opts->lock);
1311 
1312 	if (free)
1313 		f_midi_free_inst(&opts->func_inst);
1314 }
1315 
1316 static void f_midi_rmidi_free(struct snd_rawmidi *rmidi)
1317 {
1318 	f_midi_free(rmidi->private_data);
1319 }
1320 
1321 static void f_midi_unbind(struct usb_configuration *c, struct usb_function *f)
1322 {
1323 	struct usb_composite_dev *cdev = f->config->cdev;
1324 	struct f_midi *midi = func_to_midi(f);
1325 	struct snd_card *card;
1326 
1327 	DBG(cdev, "unbind\n");
1328 
1329 	/* just to be sure */
1330 	f_midi_disable(f);
1331 
1332 	card = midi->card;
1333 	midi->card = NULL;
1334 	if (card)
1335 		snd_card_free_when_closed(card);
1336 
1337 	usb_free_all_descriptors(f);
1338 }
1339 
1340 static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
1341 {
1342 	struct f_midi *midi = NULL;
1343 	struct f_midi_opts *opts;
1344 	int status, i;
1345 
1346 	opts = container_of(fi, struct f_midi_opts, func_inst);
1347 
1348 	mutex_lock(&opts->lock);
1349 	/* sanity check */
1350 	if (opts->in_ports > MAX_PORTS || opts->out_ports > MAX_PORTS) {
1351 		status = -EINVAL;
1352 		goto setup_fail;
1353 	}
1354 
1355 	/* allocate and initialize one new instance */
1356 	midi = kzalloc(struct_size(midi, in_ports_array, opts->in_ports),
1357 		       GFP_KERNEL);
1358 	if (!midi) {
1359 		status = -ENOMEM;
1360 		goto setup_fail;
1361 	}
1362 
1363 	for (i = 0; i < opts->in_ports; i++)
1364 		midi->in_ports_array[i].cable = i;
1365 
1366 	/* set up ALSA midi devices */
1367 	midi->id = kstrdup(opts->id, GFP_KERNEL);
1368 	if (opts->id && !midi->id) {
1369 		status = -ENOMEM;
1370 		goto midi_free;
1371 	}
1372 	midi->in_ports = opts->in_ports;
1373 	midi->out_ports = opts->out_ports;
1374 	midi->index = opts->index;
1375 	midi->buflen = opts->buflen;
1376 	midi->qlen = opts->qlen;
1377 	midi->in_last_port = 0;
1378 	midi->free_ref = 1;
1379 
1380 	status = kfifo_alloc(&midi->in_req_fifo, midi->qlen, GFP_KERNEL);
1381 	if (status)
1382 		goto midi_free;
1383 
1384 	spin_lock_init(&midi->transmit_lock);
1385 
1386 	++opts->refcnt;
1387 	mutex_unlock(&opts->lock);
1388 
1389 	midi->func.name		= "gmidi function";
1390 	midi->func.bind		= f_midi_bind;
1391 	midi->func.unbind	= f_midi_unbind;
1392 	midi->func.set_alt	= f_midi_set_alt;
1393 	midi->func.disable	= f_midi_disable;
1394 	midi->func.free_func	= f_midi_free;
1395 
1396 	return &midi->func;
1397 
1398 midi_free:
1399 	if (midi)
1400 		kfree(midi->id);
1401 	kfree(midi);
1402 setup_fail:
1403 	mutex_unlock(&opts->lock);
1404 
1405 	return ERR_PTR(status);
1406 }
1407 
1408 DECLARE_USB_FUNCTION_INIT(midi, f_midi_alloc_inst, f_midi_alloc);
1409