summaryrefslogtreecommitdiffstats
path: root/drivers/usb/gadget/function/f_acm.c
blob: be9df09fde26508c6b658cd0686681fb43e1d4bb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
/*
 * f_acm.c -- USB CDC serial (ACM) function driver
 *
 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
 * Copyright (C) 2008 by David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 * Copyright (C) 2009 by Samsung Electronics
 * Author: Michal Nazarewicz (mina86@mina86.com)
 *
 * This software is distributed under the terms of the GNU General
 * Public License ("GPL") as published by the Free Software Foundation,
 * either version 2 of that License or (at your option) any later version.
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>

#include "u_serial.h"


/*
 * This CDC ACM function support just wraps control functions and
 * notifications around the generic serial-over-usb code.
 *
 * Because CDC ACM is standardized by the USB-IF, many host operating
 * systems have drivers for it.  Accordingly, ACM is the preferred
 * interop solution for serial-port type connections.  The control
 * models are often not necessary, and in any case don't do much in
 * this bare-bones implementation.
 *
 * Note that even MS-Windows has some support for ACM.  However, that
 * support is somewhat broken because when you use ACM in a composite
 * device, having multiple interfaces confuses the poor OS.  It doesn't
 * seem to understand CDC Union descriptors.  The new "association"
 * descriptors (roughly equivalent to CDC Unions) may sometimes help.
 */

struct f_acm {
	struct gserial			port;
	u8				ctrl_id, data_id;
	u8				port_num;

	u8				pending;

	/* lock is mostly for pending and notify_req ... they get accessed
	 * by callbacks both from tty (open/close/break) under its spinlock,
	 * and notify_req.complete() which can't use that lock.
	 */
	spinlock_t			lock;

	struct usb_ep			*notify;
	struct usb_request		*notify_req;

	struct usb_cdc_line_coding	port_line_coding;	/* 8-N-1 etc */

	/* SetControlLineState request -- CDC 1.1 section 6.2.14 (INPUT) */
	u16				port_handshake_bits;
#define ACM_CTRL_RTS	(1 << 1)	/* unused with full duplex */
#define ACM_CTRL_DTR	(1 << 0)	/* host is ready for data r/w */

	/* SerialState notification -- CDC 1.1 section 6.3.5 (OUTPUT) */
	u16				serial_state;
#define ACM_CTRL_OVERRUN	(1 << 6)
#define ACM_CTRL_PARITY		(1 << 5)
#define ACM_CTRL_FRAMING	(1 << 4)
#define ACM_CTRL_RI		(1 << 3)
#define ACM_CTRL_BRK		(1 << 2)
#define ACM_CTRL_DSR		(1 << 1)
#define ACM_CTRL_DCD		(1 << 0)
};

static inline struct f_acm *func_to_acm(struct usb_function *f)
{
	return container_of(f, struct f_acm, port.func);
}

static inline struct f_acm *port_to_acm(struct gserial *p)
{
	return container_of(p, struct f_acm, port);
}

/*-------------------------------------------------------------------------*/

/* notification endpoint uses smallish and infrequent fixed-size messages */

#define GS_NOTIFY_INTERVAL_MS		32
#define GS_NOTIFY_MAXPACKET		10	/* notification + 2 bytes */

/* interface and class descriptors: */

static struct usb_interface_assoc_descriptor
acm_iad_descriptor = {
	.bLength =		sizeof acm_iad_descriptor,
	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,

	/* .bFirstInterface =	DYNAMIC, */
	.bInterfaceCount = 	2,	// control + data
	.bFunctionClass =	USB_CLASS_COMM,
	.bFunctionSubClass =	USB_CDC_SUBCLASS_ACM,
	.bFunctionProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
	/* .iFunction =		DYNAMIC */
};


static struct usb_interface_descriptor acm_control_interface_desc = {
	.bLength =		USB_DT_INTERFACE_SIZE,
	.bDescriptorType =	USB_DT_INTERFACE,
	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	1,
	.bInterfaceClass =	USB_CLASS_COMM,
	.bInterfaceSubClass =	USB_CDC_SUBCLASS_ACM,
	.bInterfaceProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
	/* .iInterface = DYNAMIC */
};

static struct usb_interface_descriptor acm_data_interface_desc = {
	.bLength =		USB_DT_INTERFACE_SIZE,
	.bDescriptorType =	USB_DT_INTERFACE,
	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	2,
	.bInterfaceClass =	USB_CLASS_CDC_DATA,
	.bInterfaceSubClass =	0,
	.bInterfaceProtocol =	0,
	/* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc acm_header_desc = {
	.bLength =		sizeof(acm_header_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
	.bcdCDC =		cpu_to_le16(0x0110),
};

static struct usb_cdc_call_mgmt_descriptor
acm_call_mgmt_descriptor = {
	.bLength =		sizeof(acm_call_mgmt_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
	.bmCapabilities =	0,
	/* .bDataInterface = DYNAMIC */
};

static struct usb_cdc_acm_descriptor acm_descriptor = {
	.bLength =		sizeof(acm_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
	.bmCapabilities =	USB_CDC_CAP_LINE,
};

static struct usb_cdc_union_desc acm_union_desc = {
	.bLength =		sizeof(acm_union_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
	/* .bMasterInterface0 =	DYNAMIC */
	/* .bSlaveInterface0 =	DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor acm_fs_notify_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		GS_NOTIFY_INTERVAL_MS,
};

static struct usb_endpoint_descriptor acm_fs_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor acm_fs_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_OUT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *acm_fs_function[] = {
	(struct usb_descriptor_header *) &acm_iad_descriptor,
	(struct usb_descriptor_header *) &acm_control_interface_desc,
	(struct usb_descriptor_header *) &acm_header_desc,
	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &acm_descriptor,
	(struct usb_descriptor_header *) &acm_union_desc,
	(struct usb_descriptor_header *) &acm_fs_notify_desc,
	(struct usb_descriptor_header *) &acm_data_interface_desc,
	(struct usb_descriptor_header *) &acm_fs_in_desc,
	(struct usb_descriptor_header *) &acm_fs_out_desc,
	NULL,
};

/* high speed support: */
static struct usb_endpoint_descriptor acm_hs_notify_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		USB_MS_TO_HS_INTERVAL(GS_NOTIFY_INTERVAL_MS),
};

static struct usb_endpoint_descriptor acm_hs_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
};

static struct usb_endpoint_descriptor acm_hs_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
};

static struct usb_descriptor_header *acm_hs_function[] = {
	(struct usb_descriptor_header *) &acm_iad_descriptor,
	(struct usb_descriptor_header *) &acm_control_interface_desc,
	(struct usb_descriptor_header *) &acm_header_desc,
	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &acm_descriptor,
	(struct usb_descriptor_header *) &acm_union_desc,
	(struct usb_descriptor_header *) &acm_hs_notify_desc,
	(struct usb_descriptor_header *) &acm_data_interface_desc,
	(struct usb_descriptor_header *) &acm_hs_in_desc,
	(struct usb_descriptor_header *) &acm_hs_out_desc,
	NULL,
};

static struct usb_endpoint_descriptor acm_ss_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(1024),
};

static struct usb_endpoint_descriptor acm_ss_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor acm_ss_bulk_comp_desc = {
	.bLength =              sizeof acm_ss_bulk_comp_desc,
	.bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_descriptor_header *acm_ss_function[] = {
	(struct usb_descriptor_header *) &acm_iad_descriptor,
	(struct usb_descriptor_header *) &acm_control_interface_desc,
	(struct usb_descriptor_header *) &acm_header_desc,
	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &acm_descriptor,
	(struct usb_descriptor_header *) &acm_union_desc,
	(struct usb_descriptor_header *) &acm_hs_notify_desc,
	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
	(struct usb_descriptor_header *) &acm_data_interface_desc,
	(struct usb_descriptor_header *) &acm_ss_in_desc,
	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
	(struct usb_descriptor_header *) &acm_ss_out_desc,
	(struct usb_descriptor_header *) &acm_ss_bulk_comp_desc,
	NULL,
};

/* string descriptors: */

#define ACM_CTRL_IDX	0
#define ACM_DATA_IDX	1
#define ACM_IAD_IDX	2

/* static strings, in UTF-8 */
static struct usb_string acm_string_defs[] = {
	[ACM_CTRL_IDX].s = "CDC Abstract Control Model (ACM)",
	[ACM_DATA_IDX].s = "CDC ACM Data",
	[ACM_IAD_IDX ].s = "CDC Serial",
	{  } /* end of list */
};

static struct usb_gadget_strings acm_string_table = {
	.language =		0x0409,	/* en-us */
	.strings =		acm_string_defs,
};

static struct usb_gadget_strings *acm_strings[] = {
	&acm_string_table,
	NULL,
};

/*-------------------------------------------------------------------------*/

/* ACM control ... data handling is delegated to tty library code.
 * The main task of this function is to activate and deactivate
 * that code based on device state; track parameters like line
 * speed, handshake state, and so on; and issue notifications.
 */

static void acm_complete_set_line_coding(struct usb_ep *ep,
		struct usb_request *req)
{
	struct f_acm	*acm = ep->driver_data;
	struct usb_composite_dev *cdev = acm->port.func.config->cdev;

	if (req->status != 0) {
		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d completion, err %d\n",
			acm->port_num, req->status);
		return;
	}

	/* normal completion */
	if (req->actual != sizeof(acm->port_line_coding)) {
		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d short resp, len %d\n",
			acm->port_num, req->actual);
		usb_ep_set_halt(ep);
	} else {
		struct usb_cdc_line_coding	*value = req->buf;

		/* REVISIT:  we currently just remember this data.
		 * If we change that, (a) validate it first, then
		 * (b) update whatever hardware needs updating,
		 * (c) worry about locking.  This is information on
		 * the order of 9600-8-N-1 ... most of which means
		 * nothing unless we control a real RS232 line.
		 */
		acm->port_line_coding = *value;
	}
}

static int acm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
	struct f_acm		*acm = func_to_acm(f);
	struct usb_composite_dev *cdev = f->config->cdev;
	struct usb_request	*req = cdev->req;
	int			value = -EOPNOTSUPP;
	u16			w_index = le16_to_cpu(ctrl->wIndex);
	u16			w_value = le16_to_cpu(ctrl->wValue);
	u16			w_length = le16_to_cpu(ctrl->wLength);

	/* composite driver infrastructure handles everything except
	 * CDC class messages; interface activation uses set_alt().
	 *
	 * Note CDC spec table 4 lists the ACM request profile.  It requires
	 * encapsulated command support ... we don't handle any, and respond
	 * to them by stalling.  Options include get/set/clear comm features
	 * (not that useful) and SEND_BREAK.
	 */
	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {

	/* SET_LINE_CODING ... just read and save what the host sends */
	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_SET_LINE_CODING:
		if (w_length != sizeof(struct usb_cdc_line_coding)
				|| w_index != acm->ctrl_id)
			goto invalid;

		value = w_length;
		cdev->gadget->ep0->driver_data = acm;
		req->complete = acm_complete_set_line_coding;
		break;

	/* GET_LINE_CODING ... return what host sent, or initial value */
	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_GET_LINE_CODING:
		if (w_index != acm->ctrl_id)
			goto invalid;

		value = min_t(unsigned, w_length,
				sizeof(struct usb_cdc_line_coding));
		memcpy(req->buf, &acm->port_line_coding, value);
		break;

	/* SET_CONTROL_LINE_STATE ... save what the host sent */
	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
			| USB_CDC_REQ_SET_CONTROL_LINE_STATE:
		if (w_index != acm->ctrl_id)
			goto invalid;

		value = 0;

		/* FIXME we should not allow data to flow until the
		 * host sets the ACM_CTRL_DTR bit; and when it clears
		 * that bit, we should return to that no-flow state.
		 */
		acm->port_handshake_bits = w_value;
		break;

	default:
invalid:
		dev_vdbg(&cdev->gadget->dev,
			 "invalid control req%02x.%02x v%04x i%04x l%d\n",
			 ctrl->bRequestType, ctrl->bRequest,
			 w_value, w_index, w_length);
	}

	/* respond with data transfer or status phase? */
	if (value >= 0) {
		dev_dbg(&cdev->gadget->dev,
			"acm ttyGS%d req%02x.%02x v%04x i%04x l%d\n",
			acm->port_num, ctrl->bRequestType, ctrl->bRequest,
			w_value, w_index, w_length);
		req->zero = 0;
		req->length = value;
		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
		if (value < 0)
			ERROR(cdev, "acm response on ttyGS%d, err %d\n",
					acm->port_num, value);
	}

	/* device either stalls (value < 0) or reports success */
	return value;
}

static int acm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
	struct f_acm		*acm = func_to_acm(f);
	struct usb_composite_dev *cdev = f->config->cdev;

	/* we know alt == 0, so this is an activation or a reset */

	if (intf == acm->ctrl_id) {
		if (acm->notify->driver_data) {
			dev_vdbg(&cdev->gadget->dev,
				 "reset acm control interface %d\n", intf);
			usb_ep_disable(acm->notify);
		}

		if (!acm->notify->desc)
			if (config_ep_by_speed(cdev->gadget, f, acm->notify))
				return -EINVAL;

		usb_ep_enable(acm->notify);
		acm->notify->driver_data = acm;

	} else if (intf == acm->data_id) {
		if (acm->port.in->driver_data) {
			dev_dbg(&cdev->gadget->dev,
				"reset acm ttyGS%d\n", acm->port_num);
			gserial_disconnect(&acm->port);
		}
		if (!acm->port.in->desc || !acm->port.out->desc) {
			dev_dbg(&cdev->gadget->dev,
				"activate acm ttyGS%d\n", acm->port_num);
			if (config_ep_by_speed(cdev->gadget, f,
					       acm->port.in) ||
			    config_ep_by_speed(cdev->gadget, f,
					       acm->port.out)) {
				acm->port.in->desc = NULL;
				acm->port.out->desc = NULL;
				return -EINVAL;
			}
		}
		gserial_connect(&acm->port, acm->port_num);

	} else
		return -EINVAL;

	return 0;
}

static void acm_disable(struct usb_function *f)
{
	struct f_acm	*acm = func_to_acm(f);
	struct usb_composite_dev *cdev = f->config->cdev;

	dev_dbg(&cdev->gadget->dev, "acm ttyGS%d deactivated\n", acm->port_num);
	gserial_disconnect(&acm->port);
	usb_ep_disable(acm->notify);
	acm->notify->driver_data = NULL;
}

/*-------------------------------------------------------------------------*/

/**
 * acm_cdc_notify - issue CDC notification to host
 * @acm: wraps host to be notified
 * @type: notification type
 * @value: Refer to cdc specs, wValue field.
 * @data: data to be sent
 * @length: size of data
 * Context: irqs blocked, acm->lock held, acm_notify_req non-null
 *
 * Returns zero on success or a negative errno.
 *
 * See section 6.3.5 of the CDC 1.1 specification for information
 * about the only notification we issue:  SerialState change.
 */
static int acm_cdc_notify(struct f_acm *acm, u8 type, u16 value,
		void *data, unsigned length)
{
	struct usb_ep			*ep = acm->notify;
	struct usb_request		*req;
	struct usb_cdc_notification	*notify;
	const unsigned			len = sizeof(*notify) + length;
	void				*buf;
	int				status;

	req = acm->notify_req;
	acm->notify_req = NULL;
	acm->pending = false;

	req->length = len;
	notify = req->buf;
	buf = notify + 1;

	notify->bmRequestType = USB_DIR_IN | USB_TYPE_CLASS
			| USB_RECIP_INTERFACE;
	notify->bNotificationType = type;
	notify->wValue = cpu_to_le16(value);
	notify->wIndex = cpu_to_le16(acm->ctrl_id);
	notify->wLength = cpu_to_le16(length);
	memcpy(buf, data, length);

	/* ep_queue() can complete immediately if it fills the fifo... */
	spin_unlock(&acm->lock);
	status = usb_ep_queue(ep, req, GFP_ATOMIC);
	spin_lock(&acm->lock);

	if (status < 0) {
		ERROR(acm->port.func.config->cdev,
				"acm ttyGS%d can't notify serial state, %d\n",
				acm->port_num, status);
		acm->notify_req = req;
	}

	return status;
}

static int acm_notify_serial_state(struct f_acm *acm)
{
	struct usb_composite_dev *cdev = acm->port.func.config->cdev;
	int			status;

	spin_lock(&acm->lock);
	if (acm->notify_req) {
		dev_dbg(&cdev->gadget->dev, "acm ttyGS%d serial state %04x\n",
			acm->port_num, acm->serial_state);
		status = acm_cdc_notify(acm, USB_CDC_NOTIFY_SERIAL_STATE,
				0, &acm->serial_state, sizeof(acm->serial_state));
	} else {
		acm->pending = true;
		status = 0;
	}
	spin_unlock(&acm->lock);
	return status;
}

static void acm_cdc_notify_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct f_acm		*acm = req->context;
	u8			doit = false;

	/* on this call path we do NOT hold the port spinlock,
	 * which is why ACM needs its own spinlock
	 */
	spin_lock(&acm->lock);
	if (req->status != -ESHUTDOWN)
		doit = acm->pending;
	acm->notify_req = req;
	spin_unlock(&acm->lock);

	if (doit)
		acm_notify_serial_state(acm);
}

/* connect == the TTY link is open */

static void acm_connect(struct gserial *port)
{
	struct f_acm		*acm = port_to_acm(port);

	acm->serial_state |= ACM_CTRL_DSR | ACM_CTRL_DCD;
	acm_notify_serial_state(acm);
}

static void acm_disconnect(struct gserial *port)
{
	struct f_acm		*acm = port_to_acm(port);

	acm->serial_state &= ~(ACM_CTRL_DSR | ACM_CTRL_DCD);
	acm_notify_serial_state(acm);
}

static int acm_send_break(struct gserial *port, int duration)
{
	struct f_acm		*acm = port_to_acm(port);
	u16			state;

	state = acm->serial_state;
	state &= ~ACM_CTRL_BRK;
	if (duration)
		state |= ACM_CTRL_BRK;

	acm->serial_state = state;
	return acm_notify_serial_state(acm);
}

/*-------------------------------------------------------------------------*/

/* ACM function driver setup/binding */
static int
acm_bind(struct usb_configuration *c, struct usb_function *f)
{
	struct usb_composite_dev *cdev = c->cdev;
	struct f_acm		*acm = func_to_acm(f);
	struct usb_string	*us;
	int			status;
	struct usb_ep		*ep;

	/* REVISIT might want instance-specific strings to help
	 * distinguish instances ...
	 */

	/* maybe allocate device-global string IDs, and patch descriptors */
	us = usb_gstrings_attach(cdev, acm_strings,
			ARRAY_SIZE(acm_string_defs));
	if (IS_ERR(us))
		return PTR_ERR(us);
	acm_control_interface_desc.iInterface = us[ACM_CTRL_IDX].id;
	acm_data_interface_desc.iInterface = us[ACM_DATA_IDX].id;
	acm_iad_descriptor.iFunction = us[ACM_IAD_IDX].id;

	/* allocate instance-specific interface IDs, and patch descriptors */
	status = usb_interface_id(c, f);
	if (status < 0)
		goto fail;
	acm->ctrl_id = status;
	acm_iad_descriptor.bFirstInterface = status;

	acm_control_interface_desc.bInterfaceNumber = status;
	acm_union_desc .bMasterInterface0 = status;

	status = usb_interface_id(c, f);
	if (status < 0)
		goto fail;
	acm->data_id = status;

	acm_data_interface_desc.bInterfaceNumber = status;
	acm_union_desc.bSlaveInterface0 = status;
	acm_call_mgmt_descriptor.bDataInterface = status;

	status = -ENODEV;

	/* allocate instance-specific endpoints */
	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_in_desc);
	if (!ep)
		goto fail;
	acm->port.in = ep;
	ep->driver_data = cdev;	/* claim */

	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_out_desc);
	if (!ep)
		goto fail;
	acm->port.out = ep;
	ep->driver_data = cdev;	/* claim */

	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_notify_desc);
	if (!ep)
		goto fail;
	acm->notify = ep;
	ep->driver_data = cdev;	/* claim */

	/* allocate notification */
	acm->notify_req = gs_alloc_req(ep,
			sizeof(struct usb_cdc_notification) + 2,
			GFP_KERNEL);
	if (!acm->notify_req)
		goto fail;

	acm->notify_req->complete = acm_cdc_notify_complete;
	acm->notify_req->context = acm;

	/* support all relevant hardware speeds... we expect that when
	 * hardware is dual speed, all bulk-capable endpoints work at
	 * both speeds
	 */
	acm_hs_in_desc.bEndpointAddress = acm_fs_in_desc.bEndpointAddress;
	acm_hs_out_desc.bEndpointAddress = acm_fs_out_desc.bEndpointAddress;
	acm_hs_notify_desc.bEndpointAddress =
		acm_fs_notify_desc.bEndpointAddress;

	acm_ss_in_desc.bEndpointAddress = acm_fs_in_desc.bEndpointAddress;
	acm_ss_out_desc.bEndpointAddress = acm_fs_out_desc.bEndpointAddress;

	status = usb_assign_descriptors(f, acm_fs_function, acm_hs_function,
			acm_ss_function);
	if (status)
		goto fail;

	dev_dbg(&cdev->gadget->dev,
		"acm ttyGS%d: %s speed IN/%s OUT/%s NOTIFY/%s\n",
		acm->port_num,
		gadget_is_superspeed(c->cdev->gadget) ? "super" :
		gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
		acm->port.in->name, acm->port.out->name,
		acm->notify->name);
	return 0;

fail:
	if (acm->notify_req)
		gs_free_req(acm->notify, acm->notify_req);

	/* we might as well release our claims on endpoints */
	if (acm->notify)
		acm->notify->driver_data = NULL;
	if (acm->port.out)
		acm->port.out->driver_data = NULL;
	if (acm->port.in)
		acm->port.in->driver_data = NULL;

	ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);

	return status;
}

static void acm_unbind(struct usb_configuration *c, struct usb_function *f)
{
	struct f_acm		*acm = func_to_acm(f);

	acm_string_defs[0].id = 0;
	usb_free_all_descriptors(f);
	if (acm->notify_req)
		gs_free_req(acm->notify, acm->notify_req);
}

static void acm_free_func(struct usb_function *f)
{
	struct f_acm		*acm = func_to_acm(f);

	kfree(acm);
}

static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
{
	struct f_serial_opts *opts;
	struct f_acm *acm;

	acm = kzalloc(sizeof(*acm), GFP_KERNEL);
	if (!acm)
		return ERR_PTR(-ENOMEM);

	spin_lock_init(&acm->lock);

	acm->port.connect = acm_connect;
	acm->port.disconnect = acm_disconnect;
	acm->port.send_break = acm_send_break;

	acm->port.func.name = "acm";
	acm->port.func.strings = acm_strings;
	/* descriptors are per-instance copies */
	acm->port.func.bind = acm_bind;
	acm->port.func.set_alt = acm_set_alt;
	acm->port.func.setup = acm_setup;
	acm->port.func.disable = acm_disable;

	opts = container_of(fi, struct f_serial_opts, func_inst);
	acm->port_num = opts->port_num;
	acm->port.func.unbind = acm_unbind;
	acm->port.func.free_func = acm_free_func;

	return &acm->port.func;
}

static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
{
	return container_of(to_config_group(item), struct f_serial_opts,
			func_inst.group);
}

CONFIGFS_ATTR_STRUCT(f_serial_opts);
static ssize_t f_acm_attr_show(struct config_item *item,
				 struct configfs_attribute *attr,
				 char *page)
{
	struct f_serial_opts *opts = to_f_serial_opts(item);
	struct f_serial_opts_attribute *f_serial_opts_attr =
		container_of(attr, struct f_serial_opts_attribute, attr);
	ssize_t ret = 0;

	if (f_serial_opts_attr->show)
		ret = f_serial_opts_attr->show(opts, page);
	return ret;
}

static void acm_attr_release(struct config_item *item)
{
	struct f_serial_opts *opts = to_f_serial_opts(item);

	usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations acm_item_ops = {
	.release                = acm_attr_release,
	.show_attribute		= f_acm_attr_show,
};

static ssize_t f_acm_port_num_show(struct f_serial_opts *opts, char *page)
{
	return sprintf(page, "%u\n", opts->port_num);
}

static struct f_serial_opts_attribute f_acm_port_num =
	__CONFIGFS_ATTR_RO(port_num, f_acm_port_num_show);


static struct configfs_attribute *acm_attrs[] = {
	&f_acm_port_num.attr,
	NULL,
};

static struct config_item_type acm_func_type = {
	.ct_item_ops    = &acm_item_ops,
	.ct_attrs	= acm_attrs,
	.ct_owner       = THIS_MODULE,
};

static void acm_free_instance(struct usb_function_instance *fi)
{
	struct f_serial_opts *opts;

	opts = container_of(fi, struct f_serial_opts, func_inst);
	gserial_free_line(opts->port_num);
	kfree(opts);
}

static struct usb_function_instance *acm_alloc_instance(void)
{
	struct f_serial_opts *opts;
	int ret;

	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
	if (!opts)
		return ERR_PTR(-ENOMEM);
	opts->func_inst.free_func_inst = acm_free_instance;
	ret = gserial_alloc_line(&opts->port_num);
	if (ret) {
		kfree(opts);
		return ERR_PTR(ret);
	}
	config_group_init_type_name(&opts->func_inst.group, "",
			&acm_func_type);
	return &opts->func_inst;
}
DECLARE_USB_FUNCTION_INIT(acm, acm_alloc_instance, acm_alloc_func);
MODULE_LICENSE("GPL");