aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/isdn/gigaset/ser-gigaset.c
blob: 0ef09d0eb96bfbc00600b498ba3c7ad58ec506a9 (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
/* This is the serial hardware link layer (HLL) for the Gigaset 307x isdn
 * DECT base (aka Sinus 45 isdn) using the RS232 DECT data module M101,
 * written as a line discipline.
 *
 * =====================================================================
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 * =====================================================================
 */

#include "gigaset.h"
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/completion.h>

/* Version Information */
#define DRIVER_AUTHOR "Tilman Schmidt"
#define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"

#define GIGASET_MINORS     1
#define GIGASET_MINOR      0
#define GIGASET_MODULENAME "ser_gigaset"
#define GIGASET_DEVNAME    "ttyGS"

/* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
#define IF_WRITEBUF 264

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_GIGASET_M101);

static int startmode = SM_ISDN;
module_param(startmode, int, S_IRUGO);
MODULE_PARM_DESC(startmode, "initial operation mode");
static int cidmode = 1;
module_param(cidmode, int, S_IRUGO);
MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");

static struct gigaset_driver *driver;

struct ser_cardstate {
	struct platform_device	dev;
	struct tty_struct	*tty;
	atomic_t		refcnt;
	struct completion	dead_cmp;
};

static struct platform_driver device_driver = {
	.driver = {
		.name = GIGASET_MODULENAME,
	},
};

static void flush_send_queue(struct cardstate *);

/* transmit data from current open skb
 * result: number of bytes sent or error code < 0
 */
static int write_modem(struct cardstate *cs)
{
	struct tty_struct *tty = cs->hw.ser->tty;
	struct bc_state *bcs = &cs->bcs[0];	/* only one channel */
	struct sk_buff *skb = bcs->tx_skb;
	int sent = -EOPNOTSUPP;

	if (!tty || !tty->driver || !skb)
		return -EINVAL;

	if (!skb->len) {
		dev_kfree_skb_any(skb);
		bcs->tx_skb = NULL;
		return -EINVAL;
	}

	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	if (tty->ops->write)
		sent = tty->ops->write(tty, skb->data, skb->len);
	gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
	if (sent < 0) {
		/* error */
		flush_send_queue(cs);
		return sent;
	}
	skb_pull(skb, sent);
	if (!skb->len) {
		/* skb sent completely */
		gigaset_skb_sent(bcs, skb);

		gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
			(unsigned long) skb);
		dev_kfree_skb_any(skb);
		bcs->tx_skb = NULL;
	}
	return sent;
}

/*
 * transmit first queued command buffer
 * result: number of bytes sent or error code < 0
 */
static int send_cb(struct cardstate *cs)
{
	struct tty_struct *tty = cs->hw.ser->tty;
	struct cmdbuf_t *cb, *tcb;
	unsigned long flags;
	int sent = 0;

	if (!tty || !tty->driver)
		return -EFAULT;

	cb = cs->cmdbuf;
	if (!cb)
		return 0;	/* nothing to do */

	if (cb->len) {
		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
		sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
		if (sent < 0) {
			/* error */
			gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
			flush_send_queue(cs);
			return sent;
		}
		cb->offset += sent;
		cb->len -= sent;
		gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
			sent, cb->len, cs->cmdbytes);
	}

	while (cb && !cb->len) {
		spin_lock_irqsave(&cs->cmdlock, flags);
		cs->cmdbytes -= cs->curlen;
		tcb = cb;
		cs->cmdbuf = cb = cb->next;
		if (cb) {
			cb->prev = NULL;
			cs->curlen = cb->len;
		} else {
			cs->lastcmdbuf = NULL;
			cs->curlen = 0;
		}
		spin_unlock_irqrestore(&cs->cmdlock, flags);

		if (tcb->wake_tasklet)
			tasklet_schedule(tcb->wake_tasklet);
		kfree(tcb);
	}
	return sent;
}

/*
 * send queue tasklet
 * If there is already a skb opened, put data to the transfer buffer
 * by calling "write_modem".
 * Otherwise take a new skb out of the queue.
 */
static void gigaset_modem_fill(unsigned long data)
{
	struct cardstate *cs = (struct cardstate *) data;
	struct bc_state *bcs;
	struct sk_buff *nextskb;
	int sent = 0;

	if (!cs) {
		gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
		return;
	}
	bcs = cs->bcs;
	if (!bcs) {
		gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
		return;
	}
	if (!bcs->tx_skb) {
		/* no skb is being sent; send command if any */
		sent = send_cb(cs);
		gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
		if (sent)
			/* something sent or error */
			return;

		/* no command to send; get skb */
		nextskb = skb_dequeue(&bcs->squeue);
		if (!nextskb)
			/* no skb either, nothing to do */
			return;
		bcs->tx_skb = nextskb;

		gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
			(unsigned long) bcs->tx_skb);
	}

	/* send skb */
	gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
	if (write_modem(cs) < 0)
		gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
}

/*
 * throw away all data queued for sending
 */
static void flush_send_queue(struct cardstate *cs)
{
	struct sk_buff *skb;
	struct cmdbuf_t *cb;
	unsigned long flags;

	/* command queue */
	spin_lock_irqsave(&cs->cmdlock, flags);
	while ((cb = cs->cmdbuf) != NULL) {
		cs->cmdbuf = cb->next;
		if (cb->wake_tasklet)
			tasklet_schedule(cb->wake_tasklet);
		kfree(cb);
	}
	cs->cmdbuf = cs->lastcmdbuf = NULL;
	cs->cmdbytes = cs->curlen = 0;
	spin_unlock_irqrestore(&cs->cmdlock, flags);

	/* data queue */
	if (cs->bcs->tx_skb)
		dev_kfree_skb_any(cs->bcs->tx_skb);
	while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
		dev_kfree_skb_any(skb);
}


/* Gigaset Driver Interface */
/* ======================== */

/*
 * queue an AT command string for transmission to the Gigaset device
 * parameters:
 *	cs		controller state structure
 *	buf		buffer containing the string to send
 *	len		number of characters to send
 *	wake_tasklet	tasklet to run when transmission is complete, or NULL
 * return value:
 *	number of bytes queued, or error code < 0
 */
static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb)
{
	unsigned long flags;

	gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
				DEBUG_TRANSCMD : DEBUG_LOCKCMD,
			   "CMD Transmit", cb->len, cb->buf);

	spin_lock_irqsave(&cs->cmdlock, flags);
	cb->prev = cs->lastcmdbuf;
	if (cs->lastcmdbuf)
		cs->lastcmdbuf->next = cb;
	else {
		cs->cmdbuf = cb;
		cs->curlen = cb->len;
	}
	cs->cmdbytes += cb->len;
	cs->lastcmdbuf = cb;
	spin_unlock_irqrestore(&cs->cmdlock, flags);

	spin_lock_irqsave(&cs->lock, flags);
	if (cs->connected)
		tasklet_schedule(&cs->write_tasklet);
	spin_unlock_irqrestore(&cs->lock, flags);
	return cb->len;
}

/*
 * tty_driver.write_room interface routine
 * return number of characters the driver will accept to be written
 * parameter:
 *	controller state structure
 * return value:
 *	number of characters
 */
static int gigaset_write_room(struct cardstate *cs)
{
	unsigned bytes;

	bytes = cs->cmdbytes;
	return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
}

/*
 * tty_driver.chars_in_buffer interface routine
 * return number of characters waiting to be sent
 * parameter:
 *	controller state structure
 * return value:
 *	number of characters
 */
static int gigaset_chars_in_buffer(struct cardstate *cs)
{
	return cs->cmdbytes;
}

/*
 * implementation of ioctl(GIGASET_BRKCHARS)
 * parameter:
 *	controller state structure
 * return value:
 *	-EINVAL (unimplemented function)
 */
static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
{
	/* not implemented */
	return -EINVAL;
}

/*
 * Open B channel
 * Called by "do_action" in ev-layer.c
 */
static int gigaset_init_bchannel(struct bc_state *bcs)
{
	/* nothing to do for M10x */
	gigaset_bchannel_up(bcs);
	return 0;
}

/*
 * Close B channel
 * Called by "do_action" in ev-layer.c
 */
static int gigaset_close_bchannel(struct bc_state *bcs)
{
	/* nothing to do for M10x */
	gigaset_bchannel_down(bcs);
	return 0;
}

/*
 * Set up B channel structure
 * This is called by "gigaset_initcs" in common.c
 */
static int gigaset_initbcshw(struct bc_state *bcs)
{
	/* unused */
	bcs->hw.ser = NULL;
	return 1;
}

/*
 * Free B channel structure
 * Called by "gigaset_freebcs" in common.c
 */
static int gigaset_freebcshw(struct bc_state *bcs)
{
	/* unused */
	return 1;
}

/*
 * Reinitialize B channel structure
 * This is called by "bcs_reinit" in common.c
 */
static void gigaset_reinitbcshw(struct bc_state *bcs)
{
	/* nothing to do for M10x */
}

/*
 * Free hardware specific device data
 * This will be called by "gigaset_freecs" in common.c
 */
static void gigaset_freecshw(struct cardstate *cs)
{
	tasklet_kill(&cs->write_tasklet);
	if (!cs->hw.ser)
		return;
	dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
	platform_device_unregister(&cs->hw.ser->dev);
	kfree(cs->hw.ser);
	cs->hw.ser = NULL;
}

static void gigaset_device_release(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);

	/* adapted from platform_device_release() in drivers/base/platform.c */
	kfree(dev->platform_data);
	kfree(pdev->resource);
}

/*
 * Set up hardware specific device data
 * This is called by "gigaset_initcs" in common.c
 */
static int gigaset_initcshw(struct cardstate *cs)
{
	int rc;
	struct ser_cardstate *scs;

	scs = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL);
	if (!scs) {
		pr_err("out of memory\n");
		return 0;
	}
	cs->hw.ser = scs;

	cs->hw.ser->dev.name = GIGASET_MODULENAME;
	cs->hw.ser->dev.id = cs->minor_index;
	cs->hw.ser->dev.dev.release = gigaset_device_release;
	rc = platform_device_register(&cs->hw.ser->dev);
	if (rc != 0) {
		pr_err("error %d registering platform device\n", rc);
		kfree(cs->hw.ser);
		cs->hw.ser = NULL;
		return 0;
	}
	dev_set_drvdata(&cs->hw.ser->dev.dev, cs);

	tasklet_init(&cs->write_tasklet,
		     gigaset_modem_fill, (unsigned long) cs);
	return 1;
}

/*
 * set modem control lines
 * Parameters:
 *	card state structure
 *	modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 * and by "if_lock" and "if_termios" in interface.c
 */
static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state,
				  unsigned new_state)
{
	struct tty_struct *tty = cs->hw.ser->tty;
	unsigned int set, clear;

	if (!tty || !tty->driver || !tty->ops->tiocmset)
		return -EINVAL;
	set = new_state & ~old_state;
	clear = old_state & ~new_state;
	if (!set && !clear)
		return 0;
	gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
	return tty->ops->tiocmset(tty, NULL, set, clear);
}

static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
{
	return -EINVAL;
}

static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
{
	return -EINVAL;
}

static const struct gigaset_ops ops = {
	gigaset_write_cmd,
	gigaset_write_room,
	gigaset_chars_in_buffer,
	gigaset_brkchars,
	gigaset_init_bchannel,
	gigaset_close_bchannel,
	gigaset_initbcshw,
	gigaset_freebcshw,
	gigaset_reinitbcshw,
	gigaset_initcshw,
	gigaset_freecshw,
	gigaset_set_modem_ctrl,
	gigaset_baud_rate,
	gigaset_set_line_ctrl,
	gigaset_m10x_send_skb,	/* asyncdata.c */
	gigaset_m10x_input,	/* asyncdata.c */
};


/* Line Discipline Interface */
/* ========================= */

/* helper functions for cardstate refcounting */
static struct cardstate *cs_get(struct tty_struct *tty)
{
	struct cardstate *cs = tty->disc_data;

	if (!cs || !cs->hw.ser) {
		gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
		return NULL;
	}
	atomic_inc(&cs->hw.ser->refcnt);
	return cs;
}

static void cs_put(struct cardstate *cs)
{
	if (atomic_dec_and_test(&cs->hw.ser->refcnt))
		complete(&cs->hw.ser->dead_cmp);
}

/*
 * Called by the tty driver when the line discipline is pushed onto the tty.
 * Called in process context.
 */
static int
gigaset_tty_open(struct tty_struct *tty)
{
	struct cardstate *cs;

	gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");

	pr_info(DRIVER_DESC "\n");

	if (!driver) {
		pr_err("%s: no driver structure\n", __func__);
		return -ENODEV;
	}

	/* allocate memory for our device state and initialize it */
	cs = gigaset_initcs(driver, 1, 1, 0, cidmode, GIGASET_MODULENAME);
	if (!cs)
		goto error;

	cs->dev = &cs->hw.ser->dev.dev;
	cs->hw.ser->tty = tty;
	atomic_set(&cs->hw.ser->refcnt, 1);
	init_completion(&cs->hw.ser->dead_cmp);

	tty->disc_data = cs;

	/* OK.. Initialization of the datastructures and the HW is done.. Now
	 * startup system and notify the LL that we are ready to run
	 */
	if (startmode == SM_LOCKED)
		cs->mstate = MS_LOCKED;
	if (!gigaset_start(cs)) {
		tasklet_kill(&cs->write_tasklet);
		goto error;
	}

	gig_dbg(DEBUG_INIT, "Startup of HLL done");
	return 0;

error:
	gig_dbg(DEBUG_INIT, "Startup of HLL failed");
	tty->disc_data = NULL;
	gigaset_freecs(cs);
	return -ENODEV;
}

/*
 * Called by the tty driver when the line discipline is removed.
 * Called from process context.
 */
static void
gigaset_tty_close(struct tty_struct *tty)
{
	struct cardstate *cs = tty->disc_data;

	gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");

	if (!cs) {
		gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
		return;
	}

	/* prevent other callers from entering ldisc methods */
	tty->disc_data = NULL;

	if (!cs->hw.ser)
		pr_err("%s: no hw cardstate\n", __func__);
	else {
		/* wait for running methods to finish */
		if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
			wait_for_completion(&cs->hw.ser->dead_cmp);
	}

	/* stop operations */
	gigaset_stop(cs);
	tasklet_kill(&cs->write_tasklet);
	flush_send_queue(cs);
	cs->dev = NULL;
	gigaset_freecs(cs);

	gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
}

/*
 * Called by the tty driver when the tty line is hung up.
 * Wait for I/O to driver to complete and unregister ISDN device.
 * This is already done by the close routine, so just call that.
 * Called from process context.
 */
static int gigaset_tty_hangup(struct tty_struct *tty)
{
	gigaset_tty_close(tty);
	return 0;
}

/*
 * Read on the tty.
 * Unused, received data goes only to the Gigaset driver.
 */
static ssize_t
gigaset_tty_read(struct tty_struct *tty, struct file *file,
		 unsigned char __user *buf, size_t count)
{
	return -EAGAIN;
}

/*
 * Write on the tty.
 * Unused, transmit data comes only from the Gigaset driver.
 */
static ssize_t
gigaset_tty_write(struct tty_struct *tty, struct file *file,
		  const unsigned char *buf, size_t count)
{
	return -EAGAIN;
}

/*
 * Ioctl on the tty.
 * Called in process context only.
 * May be re-entered by multiple ioctl calling threads.
 */
static int
gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
		  unsigned int cmd, unsigned long arg)
{
	struct cardstate *cs = cs_get(tty);
	int rc, val;
	int __user *p = (int __user *)arg;

	if (!cs)
		return -ENXIO;

	switch (cmd) {

	case FIONREAD:
		/* unused, always return zero */
		val = 0;
		rc = put_user(val, p);
		break;

	case TCFLSH:
		/* flush our buffers and the serial port's buffer */
		switch (arg) {
		case TCIFLUSH:
			/* no own input buffer to flush */
			break;
		case TCIOFLUSH:
		case TCOFLUSH:
			flush_send_queue(cs);
			break;
		}
		/* Pass through */

	default:
		/* pass through to underlying serial device */
		rc = n_tty_ioctl_helper(tty, file, cmd, arg);
		break;
	}
	cs_put(cs);
	return rc;
}

/*
 * Called by the tty driver when a block of data has been received.
 * Will not be re-entered while running but other ldisc functions
 * may be called in parallel.
 * Can be called from hard interrupt level as well as soft interrupt
 * level or mainline.
 * Parameters:
 *	tty	tty structure
 *	buf	buffer containing received characters
 *	cflags	buffer containing error flags for received characters (ignored)
 *	count	number of received characters
 */
static void
gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
		    char *cflags, int count)
{
	struct cardstate *cs = cs_get(tty);
	unsigned tail, head, n;
	struct inbuf_t *inbuf;

	if (!cs)
		return;
	inbuf = cs->inbuf;
	if (!inbuf) {
		dev_err(cs->dev, "%s: no inbuf\n", __func__);
		cs_put(cs);
		return;
	}

	tail = inbuf->tail;
	head = inbuf->head;
	gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
		head, tail, count);

	if (head <= tail) {
		/* possible buffer wraparound */
		n = min_t(unsigned, count, RBUFSIZE - tail);
		memcpy(inbuf->data + tail, buf, n);
		tail = (tail + n) % RBUFSIZE;
		buf += n;
		count -= n;
	}

	if (count > 0) {
		/* tail < head and some data left */
		n = head - tail - 1;
		if (count > n) {
			dev_err(cs->dev,
				"inbuf overflow, discarding %d bytes\n",
				count - n);
			count = n;
		}
		memcpy(inbuf->data + tail, buf, count);
		tail += count;
	}

	gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
	inbuf->tail = tail;

	/* Everything was received .. Push data into handler */
	gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
	gigaset_schedule_event(cs);
	cs_put(cs);
}

/*
 * Called by the tty driver when there's room for more data to send.
 */
static void
gigaset_tty_wakeup(struct tty_struct *tty)
{
	struct cardstate *cs = cs_get(tty);

	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	if (!cs)
		return;
	tasklet_schedule(&cs->write_tasklet);
	cs_put(cs);
}

static struct tty_ldisc_ops gigaset_ldisc = {
	.owner		= THIS_MODULE,
	.magic		= TTY_LDISC_MAGIC,
	.name		= "ser_gigaset",
	.open		= gigaset_tty_open,
	.close		= gigaset_tty_close,
	.hangup		= gigaset_tty_hangup,
	.read		= gigaset_tty_read,
	.write		= gigaset_tty_write,
	.ioctl		= gigaset_tty_ioctl,
	.receive_buf	= gigaset_tty_receive,
	.write_wakeup	= gigaset_tty_wakeup,
};


/* Initialization / Shutdown */
/* ========================= */

static int __init ser_gigaset_init(void)
{
	int rc;

	gig_dbg(DEBUG_INIT, "%s", __func__);
	rc = platform_driver_register(&device_driver);
	if (rc != 0) {
		pr_err("error %d registering platform driver\n", rc);
		return rc;
	}

	/* allocate memory for our driver state and initialize it */
	driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
					  GIGASET_MODULENAME, GIGASET_DEVNAME,
					  &ops, THIS_MODULE);
	if (!driver)
		goto error;

	rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc);
	if (rc != 0) {
		pr_err("error %d registering line discipline\n", rc);
		goto error;
	}

	return 0;

error:
	if (driver) {
		gigaset_freedriver(driver);
		driver = NULL;
	}
	platform_driver_unregister(&device_driver);
	return rc;
}

static void __exit ser_gigaset_exit(void)
{
	int rc;

	gig_dbg(DEBUG_INIT, "%s", __func__);

	if (driver) {
		gigaset_freedriver(driver);
		driver = NULL;
	}

	rc = tty_unregister_ldisc(N_GIGASET_M101);
	if (rc != 0)
		pr_err("error %d unregistering line discipline\n", rc);

	platform_driver_unregister(&device_driver);
}

module_init(ser_gigaset_init);
module_exit(ser_gigaset_exit);