summaryrefslogtreecommitdiffstats
path: root/drivers/net/caif/caif_spi.c
blob: 05e791f46aef7db07b5df2393db24d7a56108ab5 (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
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
/*
 * Copyright (C) ST-Ericsson AB 2010
 * Contact: Sjur Brendeland / sjur.brandeland@stericsson.com
 * Author:  Daniel Martensson / Daniel.Martensson@stericsson.com
 * License terms: GNU General Public License (GPL) version 2.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/string.h>
#include <linux/workqueue.h>
#include <linux/completion.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/debugfs.h>
#include <linux/if_arp.h>
#include <net/caif/caif_layer.h>
#include <net/caif/caif_spi.h>

#ifndef CONFIG_CAIF_SPI_SYNC
#define FLAVOR "Flavour: Vanilla.\n"
#else
#define FLAVOR "Flavour: Master CMD&LEN at start.\n"
#endif /* CONFIG_CAIF_SPI_SYNC */

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Daniel Martensson<daniel.martensson@stericsson.com>");
MODULE_DESCRIPTION("CAIF SPI driver");

/* Returns the number of padding bytes for alignment. */
#define PAD_POW2(x, pow) ((((x)&((pow)-1))==0) ? 0 : (((pow)-((x)&((pow)-1)))))

static int spi_loop;
module_param(spi_loop, bool, S_IRUGO);
MODULE_PARM_DESC(spi_loop, "SPI running in loopback mode.");

/* SPI frame alignment. */
module_param(spi_frm_align, int, S_IRUGO);
MODULE_PARM_DESC(spi_frm_align, "SPI frame alignment.");

/*
 * SPI padding options.
 * Warning: must be a base of 2 (& operation used) and can not be zero !
 */
module_param(spi_up_head_align, int, S_IRUGO);
MODULE_PARM_DESC(spi_up_head_align, "SPI uplink head alignment.");

module_param(spi_up_tail_align, int, S_IRUGO);
MODULE_PARM_DESC(spi_up_tail_align, "SPI uplink tail alignment.");

module_param(spi_down_head_align, int, S_IRUGO);
MODULE_PARM_DESC(spi_down_head_align, "SPI downlink head alignment.");

module_param(spi_down_tail_align, int, S_IRUGO);
MODULE_PARM_DESC(spi_down_tail_align, "SPI downlink tail alignment.");

#ifdef CONFIG_ARM
#define BYTE_HEX_FMT "%02X"
#else
#define BYTE_HEX_FMT "%02hhX"
#endif

#define SPI_MAX_PAYLOAD_SIZE 4096
/*
 * Threshold values for the SPI packet queue. Flowcontrol will be asserted
 * when the number of packets exceeds HIGH_WATER_MARK. It will not be
 * deasserted before the number of packets drops below LOW_WATER_MARK.
 */
#define LOW_WATER_MARK   100
#define HIGH_WATER_MARK  (LOW_WATER_MARK*5)

#ifdef CONFIG_UML

/*
 * We sometimes use UML for debugging, but it cannot handle
 * dma_alloc_coherent so we have to wrap it.
 */
static inline void *dma_alloc(dma_addr_t *daddr)
{
	return kmalloc(SPI_DMA_BUF_LEN, GFP_KERNEL);
}

static inline void dma_free(void *cpu_addr, dma_addr_t handle)
{
	kfree(cpu_addr);
}

#else

static inline void *dma_alloc(dma_addr_t *daddr)
{
	return dma_alloc_coherent(NULL, SPI_DMA_BUF_LEN, daddr,
				GFP_KERNEL);
}

static inline void dma_free(void *cpu_addr, dma_addr_t handle)
{
	dma_free_coherent(NULL, SPI_DMA_BUF_LEN, cpu_addr, handle);
}
#endif	/* CONFIG_UML */

#ifdef CONFIG_DEBUG_FS

#define DEBUGFS_BUF_SIZE	4096

static struct dentry *dbgfs_root;

static inline void driver_debugfs_create(void)
{
	dbgfs_root = debugfs_create_dir(cfspi_spi_driver.driver.name, NULL);
}

static inline void driver_debugfs_remove(void)
{
	debugfs_remove(dbgfs_root);
}

static inline void dev_debugfs_rem(struct cfspi *cfspi)
{
	debugfs_remove(cfspi->dbgfs_frame);
	debugfs_remove(cfspi->dbgfs_state);
	debugfs_remove(cfspi->dbgfs_dir);
}

static int dbgfs_open(struct inode *inode, struct file *file)
{
	file->private_data = inode->i_private;
	return 0;
}

static ssize_t dbgfs_state(struct file *file, char __user *user_buf,
			   size_t count, loff_t *ppos)
{
	char *buf;
	int len = 0;
	ssize_t size;
	struct cfspi *cfspi = file->private_data;

	buf = kzalloc(DEBUGFS_BUF_SIZE, GFP_KERNEL);
	if (!buf)
		return 0;

	/* Print out debug information. */
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"CAIF SPI debug information:\n");

	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len), FLAVOR);

	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"STATE: %d\n", cfspi->dbg_state);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Previous CMD: 0x%x\n", cfspi->pcmd);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Current CMD: 0x%x\n", cfspi->cmd);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Previous TX len: %d\n", cfspi->tx_ppck_len);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Previous RX len: %d\n", cfspi->rx_ppck_len);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Current TX len: %d\n", cfspi->tx_cpck_len);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Current RX len: %d\n", cfspi->rx_cpck_len);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Next TX len: %d\n", cfspi->tx_npck_len);
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Next RX len: %d\n", cfspi->rx_npck_len);

	if (len > DEBUGFS_BUF_SIZE)
		len = DEBUGFS_BUF_SIZE;

	size = simple_read_from_buffer(user_buf, count, ppos, buf, len);
	kfree(buf);

	return size;
}

static ssize_t print_frame(char *buf, size_t size, char *frm,
			   size_t count, size_t cut)
{
	int len = 0;
	int i;
	for (i = 0; i < count; i++) {
		len += snprintf((buf + len), (size - len),
					"[0x" BYTE_HEX_FMT "]",
					frm[i]);
		if ((i == cut) && (count > (cut * 2))) {
			/* Fast forward. */
			i = count - cut;
			len += snprintf((buf + len), (size - len),
					"--- %u bytes skipped ---\n",
					(int)(count - (cut * 2)));
		}

		if ((!(i % 10)) && i) {
			len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
					"\n");
		}
	}
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len), "\n");
	return len;
}

static ssize_t dbgfs_frame(struct file *file, char __user *user_buf,
			   size_t count, loff_t *ppos)
{
	char *buf;
	int len = 0;
	ssize_t size;
	struct cfspi *cfspi;

	cfspi = file->private_data;
	buf = kzalloc(DEBUGFS_BUF_SIZE, GFP_KERNEL);
	if (!buf)
		return 0;

	/* Print out debug information. */
	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Current frame:\n");

	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Tx data (Len: %d):\n", cfspi->tx_cpck_len);

	len += print_frame((buf + len), (DEBUGFS_BUF_SIZE - len),
			   cfspi->xfer.va_tx,
			   (cfspi->tx_cpck_len + SPI_CMD_SZ), 100);

	len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
			"Rx data (Len: %d):\n", cfspi->rx_cpck_len);

	len += print_frame((buf + len), (DEBUGFS_BUF_SIZE - len),
			   cfspi->xfer.va_rx,
			   (cfspi->rx_cpck_len + SPI_CMD_SZ), 100);

	size = simple_read_from_buffer(user_buf, count, ppos, buf, len);
	kfree(buf);

	return size;
}

static const struct file_operations dbgfs_state_fops = {
	.open = dbgfs_open,
	.read = dbgfs_state,
	.owner = THIS_MODULE
};

static const struct file_operations dbgfs_frame_fops = {
	.open = dbgfs_open,
	.read = dbgfs_frame,
	.owner = THIS_MODULE
};

static inline void dev_debugfs_add(struct cfspi *cfspi)
{
	cfspi->dbgfs_dir = debugfs_create_dir(cfspi->pdev->name, dbgfs_root);
	cfspi->dbgfs_state = debugfs_create_file("state", S_IRUGO,
						 cfspi->dbgfs_dir, cfspi,
						 &dbgfs_state_fops);
	cfspi->dbgfs_frame = debugfs_create_file("frame", S_IRUGO,
						 cfspi->dbgfs_dir, cfspi,
						 &dbgfs_frame_fops);
}

inline void cfspi_dbg_state(struct cfspi *cfspi, int state)
{
	cfspi->dbg_state = state;
};
#else

static inline void driver_debugfs_create(void)
{
}

static inline void driver_debugfs_remove(void)
{
}

static inline void dev_debugfs_add(struct cfspi *cfspi)
{
}

static inline void dev_debugfs_rem(struct cfspi *cfspi)
{
}

inline void cfspi_dbg_state(struct cfspi *cfspi, int state)
{
}
#endif				/* CONFIG_DEBUG_FS */

static LIST_HEAD(cfspi_list);
static spinlock_t cfspi_list_lock;

/* SPI uplink head alignment. */
static ssize_t show_up_head_align(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%d\n", spi_up_head_align);
}

static DRIVER_ATTR(up_head_align, S_IRUSR, show_up_head_align, NULL);

/* SPI uplink tail alignment. */
static ssize_t show_up_tail_align(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%d\n", spi_up_tail_align);
}

static DRIVER_ATTR(up_tail_align, S_IRUSR, show_up_tail_align, NULL);

/* SPI downlink head alignment. */
static ssize_t show_down_head_align(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%d\n", spi_down_head_align);
}

static DRIVER_ATTR(down_head_align, S_IRUSR, show_down_head_align, NULL);

/* SPI downlink tail alignment. */
static ssize_t show_down_tail_align(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%d\n", spi_down_tail_align);
}

static DRIVER_ATTR(down_tail_align, S_IRUSR, show_down_tail_align, NULL);

/* SPI frame alignment. */
static ssize_t show_frame_align(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%d\n", spi_frm_align);
}

static DRIVER_ATTR(frame_align, S_IRUSR, show_frame_align, NULL);

int cfspi_xmitfrm(struct cfspi *cfspi, u8 *buf, size_t len)
{
	u8 *dst = buf;
	caif_assert(buf);

	if (cfspi->slave && !cfspi->slave_talked)
		cfspi->slave_talked = true;

	do {
		struct sk_buff *skb;
		struct caif_payload_info *info;
		int spad = 0;
		int epad;

		skb = skb_dequeue(&cfspi->chead);
		if (!skb)
			break;

		/*
		 * Calculate length of frame including SPI padding.
		 * The payload position is found in the control buffer.
		 */
		info = (struct caif_payload_info *)&skb->cb;

		/*
		 * Compute head offset i.e. number of bytes to add to
		 * get the start of the payload aligned.
		 */
		if (spi_up_head_align > 1) {
			spad = 1 + PAD_POW2((info->hdr_len + 1), spi_up_head_align);
			*dst = (u8)(spad - 1);
			dst += spad;
		}

		/* Copy in CAIF frame. */
		skb_copy_bits(skb, 0, dst, skb->len);
		dst += skb->len;
		cfspi->ndev->stats.tx_packets++;
		cfspi->ndev->stats.tx_bytes += skb->len;

		/*
		 * Compute tail offset i.e. number of bytes to add to
		 * get the complete CAIF frame aligned.
		 */
		epad = PAD_POW2((skb->len + spad), spi_up_tail_align);
		dst += epad;

		dev_kfree_skb(skb);

	} while ((dst - buf) < len);

	return dst - buf;
}

int cfspi_xmitlen(struct cfspi *cfspi)
{
	struct sk_buff *skb = NULL;
	int frm_len = 0;
	int pkts = 0;

	/*
	 * Decommit previously committed frames.
	 * skb_queue_splice_tail(&cfspi->chead,&cfspi->qhead)
	 */
	while (skb_peek(&cfspi->chead)) {
		skb = skb_dequeue_tail(&cfspi->chead);
		skb_queue_head(&cfspi->qhead, skb);
	}

	do {
		struct caif_payload_info *info = NULL;
		int spad = 0;
		int epad = 0;

		skb = skb_dequeue(&cfspi->qhead);
		if (!skb)
			break;

		/*
		 * Calculate length of frame including SPI padding.
		 * The payload position is found in the control buffer.
		 */
		info = (struct caif_payload_info *)&skb->cb;

		/*
		 * Compute head offset i.e. number of bytes to add to
		 * get the start of the payload aligned.
		 */
		if (spi_up_head_align > 1)
			spad = 1 + PAD_POW2((info->hdr_len + 1), spi_up_head_align);

		/*
		 * Compute tail offset i.e. number of bytes to add to
		 * get the complete CAIF frame aligned.
		 */
		epad = PAD_POW2((skb->len + spad), spi_up_tail_align);

		if ((skb->len + spad + epad + frm_len) <= CAIF_MAX_SPI_FRAME) {
			skb_queue_tail(&cfspi->chead, skb);
			pkts++;
			frm_len += skb->len + spad + epad;
		} else {
			/* Put back packet. */
			skb_queue_head(&cfspi->qhead, skb);
			break;
		}
	} while (pkts <= CAIF_MAX_SPI_PKTS);

	/*
	 * Send flow on if previously sent flow off
	 * and now go below the low water mark
	 */
	if (cfspi->flow_off_sent && cfspi->qhead.qlen < cfspi->qd_low_mark &&
		cfspi->cfdev.flowctrl) {
		cfspi->flow_off_sent = 0;
		cfspi->cfdev.flowctrl(cfspi->ndev, 1);
	}

	return frm_len;
}

static void cfspi_ss_cb(bool assert, struct cfspi_ifc *ifc)
{
	struct cfspi *cfspi = (struct cfspi *)ifc->priv;

	/*
	 * The slave device is the master on the link. Interrupts before the
	 * slave has transmitted are considered spurious.
	 */
	if (cfspi->slave && !cfspi->slave_talked) {
		printk(KERN_WARNING "CFSPI: Spurious SS interrupt.\n");
		return;
	}

	if (!in_interrupt())
		spin_lock(&cfspi->lock);
	if (assert) {
		set_bit(SPI_SS_ON, &cfspi->state);
		set_bit(SPI_XFER, &cfspi->state);
	} else {
		set_bit(SPI_SS_OFF, &cfspi->state);
	}
	if (!in_interrupt())
		spin_unlock(&cfspi->lock);

	/* Wake up the xfer thread. */
	if (assert)
		wake_up_interruptible(&cfspi->wait);
}

static void cfspi_xfer_done_cb(struct cfspi_ifc *ifc)
{
	struct cfspi *cfspi = (struct cfspi *)ifc->priv;

	/* Transfer done, complete work queue */
	complete(&cfspi->comp);
}

static int cfspi_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct cfspi *cfspi = NULL;
	unsigned long flags;
	if (!dev)
		return -EINVAL;

	cfspi = netdev_priv(dev);

	skb_queue_tail(&cfspi->qhead, skb);

	spin_lock_irqsave(&cfspi->lock, flags);
	if (!test_and_set_bit(SPI_XFER, &cfspi->state)) {
		/* Wake up xfer thread. */
		wake_up_interruptible(&cfspi->wait);
	}
	spin_unlock_irqrestore(&cfspi->lock, flags);

	/* Send flow off if number of bytes is above high water mark */
	if (!cfspi->flow_off_sent &&
		cfspi->qhead.qlen > cfspi->qd_high_mark &&
		cfspi->cfdev.flowctrl) {
		cfspi->flow_off_sent = 1;
		cfspi->cfdev.flowctrl(cfspi->ndev, 0);
	}

	return 0;
}

int cfspi_rxfrm(struct cfspi *cfspi, u8 *buf, size_t len)
{
	u8 *src = buf;

	caif_assert(buf != NULL);

	do {
		int res;
		struct sk_buff *skb = NULL;
		int spad = 0;
		int epad = 0;
		u8 *dst = NULL;
		int pkt_len = 0;

		/*
		 * Compute head offset i.e. number of bytes added to
		 * get the start of the payload aligned.
		 */
		if (spi_down_head_align > 1) {
			spad = 1 + *src;
			src += spad;
		}

		/* Read length of CAIF frame (little endian). */
		pkt_len = *src;
		pkt_len |= ((*(src+1)) << 8) & 0xFF00;
		pkt_len += 2;	/* Add FCS fields. */

		/* Get a suitable caif packet and copy in data. */

		skb = netdev_alloc_skb(cfspi->ndev, pkt_len + 1);
		caif_assert(skb != NULL);

		dst = skb_put(skb, pkt_len);
		memcpy(dst, src, pkt_len);
		src += pkt_len;

		skb->protocol = htons(ETH_P_CAIF);
		skb_reset_mac_header(skb);
		skb->dev = cfspi->ndev;

		/*
		 * Push received packet up the stack.
		 */
		if (!spi_loop)
			res = netif_rx_ni(skb);
		else
			res = cfspi_xmit(skb, cfspi->ndev);

		if (!res) {
			cfspi->ndev->stats.rx_packets++;
			cfspi->ndev->stats.rx_bytes += pkt_len;
		} else
			cfspi->ndev->stats.rx_dropped++;

		/*
		 * Compute tail offset i.e. number of bytes added to
		 * get the complete CAIF frame aligned.
		 */
		epad = PAD_POW2((pkt_len + spad), spi_down_tail_align);
		src += epad;
	} while ((src - buf) < len);

	return src - buf;
}

static int cfspi_open(struct net_device *dev)
{
	netif_wake_queue(dev);
	return 0;
}

static int cfspi_close(struct net_device *dev)
{
	netif_stop_queue(dev);
	return 0;
}
static const struct net_device_ops cfspi_ops = {
	.ndo_open = cfspi_open,
	.ndo_stop = cfspi_close,
	.ndo_start_xmit = cfspi_xmit
};

static void cfspi_setup(struct net_device *dev)
{
	struct cfspi *cfspi = netdev_priv(dev);
	dev->features = 0;
	dev->netdev_ops = &cfspi_ops;
	dev->type = ARPHRD_CAIF;
	dev->flags = IFF_NOARP | IFF_POINTOPOINT;
	dev->tx_queue_len = 0;
	dev->mtu = SPI_MAX_PAYLOAD_SIZE;
	dev->destructor = free_netdev;
	skb_queue_head_init(&cfspi->qhead);
	skb_queue_head_init(&cfspi->chead);
	cfspi->cfdev.link_select = CAIF_LINK_HIGH_BANDW;
	cfspi->cfdev.use_frag = false;
	cfspi->cfdev.use_stx = false;
	cfspi->cfdev.use_fcs = false;
	cfspi->ndev = dev;
}

int cfspi_spi_probe(struct platform_device *pdev)
{
	struct cfspi *cfspi = NULL;
	struct net_device *ndev;
	struct cfspi_dev *dev;
	int res;
	dev = (struct cfspi_dev *)pdev->dev.platform_data;

	ndev = alloc_netdev(sizeof(struct cfspi),
			"cfspi%d", cfspi_setup);
	if (!ndev)
		return -ENOMEM;

	cfspi = netdev_priv(ndev);
	netif_stop_queue(ndev);
	cfspi->ndev = ndev;
	cfspi->pdev = pdev;

	/* Set flow info. */
	cfspi->flow_off_sent = 0;
	cfspi->qd_low_mark = LOW_WATER_MARK;
	cfspi->qd_high_mark = HIGH_WATER_MARK;

	/* Set slave info. */
	if (!strncmp(cfspi_spi_driver.driver.name, "cfspi_sspi", 10)) {
		cfspi->slave = true;
		cfspi->slave_talked = false;
	} else {
		cfspi->slave = false;
		cfspi->slave_talked = false;
	}

	/* Assign the SPI device. */
	cfspi->dev = dev;
	/* Assign the device ifc to this SPI interface. */
	dev->ifc = &cfspi->ifc;

	/* Allocate DMA buffers. */
	cfspi->xfer.va_tx = dma_alloc(&cfspi->xfer.pa_tx);
	if (!cfspi->xfer.va_tx) {
		res = -ENODEV;
		goto err_dma_alloc_tx;
	}

	cfspi->xfer.va_rx = dma_alloc(&cfspi->xfer.pa_rx);

	if (!cfspi->xfer.va_rx) {
		res = -ENODEV;
		goto err_dma_alloc_rx;
	}

	/* Initialize the work queue. */
	INIT_WORK(&cfspi->work, cfspi_xfer);

	/* Initialize spin locks. */
	spin_lock_init(&cfspi->lock);

	/* Initialize flow control state. */
	cfspi->flow_stop = false;

	/* Initialize wait queue. */
	init_waitqueue_head(&cfspi->wait);

	/* Create work thread. */
	cfspi->wq = create_singlethread_workqueue(dev->name);
	if (!cfspi->wq) {
		printk(KERN_WARNING "CFSPI: failed to create work queue.\n");
		res = -ENODEV;
		goto err_create_wq;
	}

	/* Initialize work queue. */
	init_completion(&cfspi->comp);

	/* Create debugfs entries. */
	dev_debugfs_add(cfspi);

	/* Set up the ifc. */
	cfspi->ifc.ss_cb = cfspi_ss_cb;
	cfspi->ifc.xfer_done_cb = cfspi_xfer_done_cb;
	cfspi->ifc.priv = cfspi;

	/* Add CAIF SPI device to list. */
	spin_lock(&cfspi_list_lock);
	list_add_tail(&cfspi->list, &cfspi_list);
	spin_unlock(&cfspi_list_lock);

	/* Schedule the work queue. */
	queue_work(cfspi->wq, &cfspi->work);

	/* Register network device. */
	res = register_netdev(ndev);
	if (res) {
		printk(KERN_ERR "CFSPI: Reg. error: %d.\n", res);
		goto err_net_reg;
	}
	return res;

 err_net_reg:
	dev_debugfs_rem(cfspi);
	set_bit(SPI_TERMINATE, &cfspi->state);
	wake_up_interruptible(&cfspi->wait);
	destroy_workqueue(cfspi->wq);
 err_create_wq:
	dma_free(cfspi->xfer.va_rx, cfspi->xfer.pa_rx);
 err_dma_alloc_rx:
	dma_free(cfspi->xfer.va_tx, cfspi->xfer.pa_tx);
 err_dma_alloc_tx:
	free_netdev(ndev);

	return res;
}

int cfspi_spi_remove(struct platform_device *pdev)
{
	struct list_head *list_node;
	struct list_head *n;
	struct cfspi *cfspi = NULL;
	struct cfspi_dev *dev;

	dev = (struct cfspi_dev *)pdev->dev.platform_data;
	spin_lock(&cfspi_list_lock);
	list_for_each_safe(list_node, n, &cfspi_list) {
		cfspi = list_entry(list_node, struct cfspi, list);
		/* Find the corresponding device. */
		if (cfspi->dev == dev) {
			/* Remove from list. */
			list_del(list_node);
			/* Free DMA buffers. */
			dma_free(cfspi->xfer.va_rx, cfspi->xfer.pa_rx);
			dma_free(cfspi->xfer.va_tx, cfspi->xfer.pa_tx);
			set_bit(SPI_TERMINATE, &cfspi->state);
			wake_up_interruptible(&cfspi->wait);
			destroy_workqueue(cfspi->wq);
			/* Destroy debugfs directory and files. */
			dev_debugfs_rem(cfspi);
			unregister_netdev(cfspi->ndev);
			spin_unlock(&cfspi_list_lock);
			return 0;
		}
	}
	spin_unlock(&cfspi_list_lock);
	return -ENODEV;
}

static void __exit cfspi_exit_module(void)
{
	struct list_head *list_node;
	struct list_head *n;
	struct cfspi *cfspi = NULL;

	list_for_each_safe(list_node, n, &cfspi_list) {
		cfspi = list_entry(list_node, struct cfspi, list);
		platform_device_unregister(cfspi->pdev);
	}

	/* Destroy sysfs files. */
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_up_head_align);
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_up_tail_align);
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_down_head_align);
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_down_tail_align);
	driver_remove_file(&cfspi_spi_driver.driver, &driver_attr_frame_align);
	/* Unregister platform driver. */
	platform_driver_unregister(&cfspi_spi_driver);
	/* Destroy debugfs root directory. */
	driver_debugfs_remove();
}

static int __init cfspi_init_module(void)
{
	int result;

	/* Initialize spin lock. */
	spin_lock_init(&cfspi_list_lock);

	/* Register platform driver. */
	result = platform_driver_register(&cfspi_spi_driver);
	if (result) {
		printk(KERN_ERR "Could not register platform SPI driver.\n");
		goto err_dev_register;
	}

	/* Create sysfs files. */
	result =
	    driver_create_file(&cfspi_spi_driver.driver,
			       &driver_attr_up_head_align);
	if (result) {
		printk(KERN_ERR "Sysfs creation failed 1.\n");
		goto err_create_up_head_align;
	}

	result =
	    driver_create_file(&cfspi_spi_driver.driver,
			       &driver_attr_up_tail_align);
	if (result) {
		printk(KERN_ERR "Sysfs creation failed 2.\n");
		goto err_create_up_tail_align;
	}

	result =
	    driver_create_file(&cfspi_spi_driver.driver,
			       &driver_attr_down_head_align);
	if (result) {
		printk(KERN_ERR "Sysfs creation failed 3.\n");
		goto err_create_down_head_align;
	}

	result =
	    driver_create_file(&cfspi_spi_driver.driver,
			       &driver_attr_down_tail_align);
	if (result) {
		printk(KERN_ERR "Sysfs creation failed 4.\n");
		goto err_create_down_tail_align;
	}

	result =
	    driver_create_file(&cfspi_spi_driver.driver,
			       &driver_attr_frame_align);
	if (result) {
		printk(KERN_ERR "Sysfs creation failed 5.\n");
		goto err_create_frame_align;
	}
	driver_debugfs_create();
	return result;

 err_create_frame_align:
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_down_tail_align);
 err_create_down_tail_align:
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_down_head_align);
 err_create_down_head_align:
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_up_tail_align);
 err_create_up_tail_align:
	driver_remove_file(&cfspi_spi_driver.driver,
			   &driver_attr_up_head_align);
 err_create_up_head_align:
 err_dev_register:
	return result;
}

module_init(cfspi_init_module);
module_exit(cfspi_exit_module);