summaryrefslogtreecommitdiffstats
path: root/drivers/hid/hid-mcp2221.c
blob: 560eeec4035aa18036f0ae137aeca04c4660cb5a (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
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
// SPDX-License-Identifier: GPL-2.0-only
/*
 * MCP2221A - Microchip USB to I2C Host Protocol Bridge
 *
 * Copyright (c) 2020, Rishi Gupta <gupt21@gmail.com>
 *
 * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/20005565B.pdf
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/hid.h>
#include <linux/hidraw.h>
#include <linux/i2c.h>
#include <linux/gpio/driver.h>
#include "hid-ids.h"

/* Commands codes in a raw output report */
enum {
	MCP2221_I2C_WR_DATA = 0x90,
	MCP2221_I2C_WR_NO_STOP = 0x94,
	MCP2221_I2C_RD_DATA = 0x91,
	MCP2221_I2C_RD_RPT_START = 0x93,
	MCP2221_I2C_GET_DATA = 0x40,
	MCP2221_I2C_PARAM_OR_STATUS	= 0x10,
	MCP2221_I2C_SET_SPEED = 0x20,
	MCP2221_I2C_CANCEL = 0x10,
	MCP2221_GPIO_SET = 0x50,
	MCP2221_GPIO_GET = 0x51,
};

/* Response codes in a raw input report */
enum {
	MCP2221_SUCCESS = 0x00,
	MCP2221_I2C_ENG_BUSY = 0x01,
	MCP2221_I2C_START_TOUT = 0x12,
	MCP2221_I2C_STOP_TOUT = 0x62,
	MCP2221_I2C_WRADDRL_TOUT = 0x23,
	MCP2221_I2C_WRDATA_TOUT = 0x44,
	MCP2221_I2C_WRADDRL_NACK = 0x25,
	MCP2221_I2C_MASK_ADDR_NACK = 0x40,
	MCP2221_I2C_WRADDRL_SEND = 0x21,
	MCP2221_I2C_ADDR_NACK = 0x25,
	MCP2221_I2C_READ_COMPL = 0x55,
	MCP2221_ALT_F_NOT_GPIOV = 0xEE,
	MCP2221_ALT_F_NOT_GPIOD = 0xEF,
};

/* MCP GPIO direction encoding */
enum {
	MCP2221_DIR_OUT = 0x00,
	MCP2221_DIR_IN = 0x01,
};

#define MCP_NGPIO	4

/* MCP GPIO set command layout */
struct mcp_set_gpio {
	u8 cmd;
	u8 dummy;
	struct {
		u8 change_value;
		u8 value;
		u8 change_direction;
		u8 direction;
	} gpio[MCP_NGPIO];
} __packed;

/* MCP GPIO get command layout */
struct mcp_get_gpio {
	u8 cmd;
	u8 dummy;
	struct {
		u8 direction;
		u8 value;
	} gpio[MCP_NGPIO];
} __packed;

/*
 * There is no way to distinguish responses. Therefore next command
 * is sent only after response to previous has been received. Mutex
 * lock is used for this purpose mainly.
 */
struct mcp2221 {
	struct hid_device *hdev;
	struct i2c_adapter adapter;
	struct mutex lock;
	struct completion wait_in_report;
	u8 *rxbuf;
	u8 txbuf[64];
	int rxbuf_idx;
	int status;
	u8 cur_i2c_clk_div;
	struct gpio_chip *gc;
	u8 gp_idx;
	u8 gpio_dir;
};

/*
 * Default i2c bus clock frequency 400 kHz. Modify this if you
 * want to set some other frequency (min 50 kHz - max 400 kHz).
 */
static uint i2c_clk_freq = 400;

/* Synchronously send output report to the device */
static int mcp_send_report(struct mcp2221 *mcp,
					u8 *out_report, size_t len)
{
	u8 *buf;
	int ret;

	buf = kmemdup(out_report, len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	/* mcp2221 uses interrupt endpoint for out reports */
	ret = hid_hw_output_report(mcp->hdev, buf, len);
	kfree(buf);

	if (ret < 0)
		return ret;
	return 0;
}

/*
 * Send o/p report to the device and wait for i/p report to be
 * received from the device. If the device does not respond,
 * we timeout.
 */
static int mcp_send_data_req_status(struct mcp2221 *mcp,
			u8 *out_report, int len)
{
	int ret;
	unsigned long t;

	reinit_completion(&mcp->wait_in_report);

	ret = mcp_send_report(mcp, out_report, len);
	if (ret)
		return ret;

	t = wait_for_completion_timeout(&mcp->wait_in_report,
							msecs_to_jiffies(4000));
	if (!t)
		return -ETIMEDOUT;

	return mcp->status;
}

/* Check pass/fail for actual communication with i2c slave */
static int mcp_chk_last_cmd_status(struct mcp2221 *mcp)
{
	memset(mcp->txbuf, 0, 8);
	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;

	return mcp_send_data_req_status(mcp, mcp->txbuf, 8);
}

/* Cancels last command releasing i2c bus just in case occupied */
static int mcp_cancel_last_cmd(struct mcp2221 *mcp)
{
	memset(mcp->txbuf, 0, 8);
	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
	mcp->txbuf[2] = MCP2221_I2C_CANCEL;

	return mcp_send_data_req_status(mcp, mcp->txbuf, 8);
}

static int mcp_set_i2c_speed(struct mcp2221 *mcp)
{
	int ret;

	memset(mcp->txbuf, 0, 8);
	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
	mcp->txbuf[3] = MCP2221_I2C_SET_SPEED;
	mcp->txbuf[4] = mcp->cur_i2c_clk_div;

	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 8);
	if (ret) {
		/* Small delay is needed here */
		usleep_range(980, 1000);
		mcp_cancel_last_cmd(mcp);
	}

	return 0;
}

/*
 * An output report can contain minimum 1 and maximum 60 user data
 * bytes. If the number of data bytes is more then 60, we send it
 * in chunks of 60 bytes. Last chunk may contain exactly 60 or less
 * bytes. Total number of bytes is informed in very first report to
 * mcp2221, from that point onwards it first collect all the data
 * from host and then send to i2c slave device.
 */
static int mcp_i2c_write(struct mcp2221 *mcp,
				struct i2c_msg *msg, int type, u8 last_status)
{
	int ret, len, idx, sent;

	idx = 0;
	sent  = 0;
	if (msg->len < 60)
		len = msg->len;
	else
		len = 60;

	do {
		mcp->txbuf[0] = type;
		mcp->txbuf[1] = msg->len & 0xff;
		mcp->txbuf[2] = msg->len >> 8;
		mcp->txbuf[3] = (u8)(msg->addr << 1);

		memcpy(&mcp->txbuf[4], &msg->buf[idx], len);

		ret = mcp_send_data_req_status(mcp, mcp->txbuf, len + 4);
		if (ret)
			return ret;

		usleep_range(980, 1000);

		if (last_status) {
			ret = mcp_chk_last_cmd_status(mcp);
			if (ret)
				return ret;
		}

		sent = sent + len;
		if (sent >= msg->len)
			break;

		idx = idx + len;
		if ((msg->len - sent) < 60)
			len = msg->len - sent;
		else
			len = 60;

		/*
		 * Testing shows delay is needed between successive writes
		 * otherwise next write fails on first-try from i2c core.
		 * This value is obtained through automated stress testing.
		 */
		usleep_range(980, 1000);
	} while (len > 0);

	return ret;
}

/*
 * Device reads all data (0 - 65535 bytes) from i2c slave device and
 * stores it in device itself. This data is read back from device to
 * host in multiples of 60 bytes using input reports.
 */
static int mcp_i2c_smbus_read(struct mcp2221 *mcp,
				struct i2c_msg *msg, int type, u16 smbus_addr,
				u8 smbus_len, u8 *smbus_buf)
{
	int ret;
	u16 total_len;

	mcp->txbuf[0] = type;
	if (msg) {
		mcp->txbuf[1] = msg->len & 0xff;
		mcp->txbuf[2] = msg->len >> 8;
		mcp->txbuf[3] = (u8)(msg->addr << 1);
		total_len = msg->len;
		mcp->rxbuf = msg->buf;
	} else {
		mcp->txbuf[1] = smbus_len;
		mcp->txbuf[2] = 0;
		mcp->txbuf[3] = (u8)(smbus_addr << 1);
		total_len = smbus_len;
		mcp->rxbuf = smbus_buf;
	}

	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 4);
	if (ret)
		return ret;

	mcp->rxbuf_idx = 0;

	do {
		memset(mcp->txbuf, 0, 4);
		mcp->txbuf[0] = MCP2221_I2C_GET_DATA;

		ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
		if (ret)
			return ret;

		ret = mcp_chk_last_cmd_status(mcp);
		if (ret)
			return ret;

		usleep_range(980, 1000);
	} while (mcp->rxbuf_idx < total_len);

	return ret;
}

static int mcp_i2c_xfer(struct i2c_adapter *adapter,
				struct i2c_msg msgs[], int num)
{
	int ret;
	struct mcp2221 *mcp = i2c_get_adapdata(adapter);

	hid_hw_power(mcp->hdev, PM_HINT_FULLON);

	mutex_lock(&mcp->lock);

	/* Setting speed before every transaction is required for mcp2221 */
	ret = mcp_set_i2c_speed(mcp);
	if (ret)
		goto exit;

	if (num == 1) {
		if (msgs->flags & I2C_M_RD) {
			ret = mcp_i2c_smbus_read(mcp, msgs, MCP2221_I2C_RD_DATA,
							0, 0, NULL);
		} else {
			ret = mcp_i2c_write(mcp, msgs, MCP2221_I2C_WR_DATA, 1);
		}
		if (ret)
			goto exit;
		ret = num;
	} else if (num == 2) {
		/* Ex transaction; send reg address and read its contents */
		if (msgs[0].addr == msgs[1].addr &&
			!(msgs[0].flags & I2C_M_RD) &&
			 (msgs[1].flags & I2C_M_RD)) {

			ret = mcp_i2c_write(mcp, &msgs[0],
						MCP2221_I2C_WR_NO_STOP, 0);
			if (ret)
				goto exit;

			ret = mcp_i2c_smbus_read(mcp, &msgs[1],
						MCP2221_I2C_RD_RPT_START,
						0, 0, NULL);
			if (ret)
				goto exit;
			ret = num;
		} else {
			dev_err(&adapter->dev,
				"unsupported multi-msg i2c transaction\n");
			ret = -EOPNOTSUPP;
		}
	} else {
		dev_err(&adapter->dev,
			"unsupported multi-msg i2c transaction\n");
		ret = -EOPNOTSUPP;
	}

exit:
	hid_hw_power(mcp->hdev, PM_HINT_NORMAL);
	mutex_unlock(&mcp->lock);
	return ret;
}

static int mcp_smbus_write(struct mcp2221 *mcp, u16 addr,
				u8 command, u8 *buf, u8 len, int type,
				u8 last_status)
{
	int data_len, ret;

	mcp->txbuf[0] = type;
	mcp->txbuf[1] = len + 1; /* 1 is due to command byte itself */
	mcp->txbuf[2] = 0;
	mcp->txbuf[3] = (u8)(addr << 1);
	mcp->txbuf[4] = command;

	switch (len) {
	case 0:
		data_len = 5;
		break;
	case 1:
		mcp->txbuf[5] = buf[0];
		data_len = 6;
		break;
	case 2:
		mcp->txbuf[5] = buf[0];
		mcp->txbuf[6] = buf[1];
		data_len = 7;
		break;
	default:
		if (len > I2C_SMBUS_BLOCK_MAX)
			return -EINVAL;

		memcpy(&mcp->txbuf[5], buf, len);
		data_len = len + 5;
	}

	ret = mcp_send_data_req_status(mcp, mcp->txbuf, data_len);
	if (ret)
		return ret;

	if (last_status) {
		usleep_range(980, 1000);

		ret = mcp_chk_last_cmd_status(mcp);
		if (ret)
			return ret;
	}

	return ret;
}

static int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
				unsigned short flags, char read_write,
				u8 command, int size,
				union i2c_smbus_data *data)
{
	int ret;
	struct mcp2221 *mcp = i2c_get_adapdata(adapter);

	hid_hw_power(mcp->hdev, PM_HINT_FULLON);

	mutex_lock(&mcp->lock);

	ret = mcp_set_i2c_speed(mcp);
	if (ret)
		goto exit;

	switch (size) {

	case I2C_SMBUS_QUICK:
		if (read_write == I2C_SMBUS_READ)
			ret = mcp_i2c_smbus_read(mcp, NULL, MCP2221_I2C_RD_DATA,
						addr, 0, &data->byte);
		else
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_DATA, 1);
		break;
	case I2C_SMBUS_BYTE:
		if (read_write == I2C_SMBUS_READ)
			ret = mcp_i2c_smbus_read(mcp, NULL, MCP2221_I2C_RD_DATA,
						addr, 1, &data->byte);
		else
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_DATA, 1);
		break;
	case I2C_SMBUS_BYTE_DATA:
		if (read_write == I2C_SMBUS_READ) {
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_NO_STOP, 0);
			if (ret)
				goto exit;

			ret = mcp_i2c_smbus_read(mcp, NULL,
						MCP2221_I2C_RD_RPT_START,
						addr, 1, &data->byte);
		} else {
			ret = mcp_smbus_write(mcp, addr, command, &data->byte,
						1, MCP2221_I2C_WR_DATA, 1);
		}
		break;
	case I2C_SMBUS_WORD_DATA:
		if (read_write == I2C_SMBUS_READ) {
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_NO_STOP, 0);
			if (ret)
				goto exit;

			ret = mcp_i2c_smbus_read(mcp, NULL,
						MCP2221_I2C_RD_RPT_START,
						addr, 2, (u8 *)&data->word);
		} else {
			ret = mcp_smbus_write(mcp, addr, command,
						(u8 *)&data->word, 2,
						MCP2221_I2C_WR_DATA, 1);
		}
		break;
	case I2C_SMBUS_BLOCK_DATA:
		if (read_write == I2C_SMBUS_READ) {
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_NO_STOP, 1);
			if (ret)
				goto exit;

			mcp->rxbuf_idx = 0;
			mcp->rxbuf = data->block;
			mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
			ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
			if (ret)
				goto exit;
		} else {
			if (!data->block[0]) {
				ret = -EINVAL;
				goto exit;
			}
			ret = mcp_smbus_write(mcp, addr, command, data->block,
						data->block[0] + 1,
						MCP2221_I2C_WR_DATA, 1);
		}
		break;
	case I2C_SMBUS_I2C_BLOCK_DATA:
		if (read_write == I2C_SMBUS_READ) {
			ret = mcp_smbus_write(mcp, addr, command, NULL,
						0, MCP2221_I2C_WR_NO_STOP, 1);
			if (ret)
				goto exit;

			mcp->rxbuf_idx = 0;
			mcp->rxbuf = data->block;
			mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
			ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
			if (ret)
				goto exit;
		} else {
			if (!data->block[0]) {
				ret = -EINVAL;
				goto exit;
			}
			ret = mcp_smbus_write(mcp, addr, command,
						&data->block[1], data->block[0],
						MCP2221_I2C_WR_DATA, 1);
		}
		break;
	case I2C_SMBUS_PROC_CALL:
		ret = mcp_smbus_write(mcp, addr, command,
						(u8 *)&data->word,
						2, MCP2221_I2C_WR_NO_STOP, 0);
		if (ret)
			goto exit;

		ret = mcp_i2c_smbus_read(mcp, NULL,
						MCP2221_I2C_RD_RPT_START,
						addr, 2, (u8 *)&data->word);
		break;
	case I2C_SMBUS_BLOCK_PROC_CALL:
		ret = mcp_smbus_write(mcp, addr, command, data->block,
						data->block[0] + 1,
						MCP2221_I2C_WR_NO_STOP, 0);
		if (ret)
			goto exit;

		ret = mcp_i2c_smbus_read(mcp, NULL,
						MCP2221_I2C_RD_RPT_START,
						addr, I2C_SMBUS_BLOCK_MAX,
						data->block);
		break;
	default:
		dev_err(&mcp->adapter.dev,
			"unsupported smbus transaction size:%d\n", size);
		ret = -EOPNOTSUPP;
	}

exit:
	hid_hw_power(mcp->hdev, PM_HINT_NORMAL);
	mutex_unlock(&mcp->lock);
	return ret;
}

static u32 mcp_i2c_func(struct i2c_adapter *adapter)
{
	return I2C_FUNC_I2C |
			I2C_FUNC_SMBUS_READ_BLOCK_DATA |
			I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
			(I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_PEC);
}

static const struct i2c_algorithm mcp_i2c_algo = {
	.master_xfer = mcp_i2c_xfer,
	.smbus_xfer = mcp_smbus_xfer,
	.functionality = mcp_i2c_func,
};

static int mcp_gpio_get(struct gpio_chip *gc,
				unsigned int offset)
{
	int ret;
	struct mcp2221 *mcp = gpiochip_get_data(gc);

	mcp->txbuf[0] = MCP2221_GPIO_GET;

	mcp->gp_idx = offsetof(struct mcp_get_gpio, gpio[offset].value);

	mutex_lock(&mcp->lock);
	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
	mutex_unlock(&mcp->lock);

	return ret;
}

static void mcp_gpio_set(struct gpio_chip *gc,
				unsigned int offset, int value)
{
	struct mcp2221 *mcp = gpiochip_get_data(gc);

	memset(mcp->txbuf, 0, 18);
	mcp->txbuf[0] = MCP2221_GPIO_SET;

	mcp->gp_idx = offsetof(struct mcp_set_gpio, gpio[offset].value);

	mcp->txbuf[mcp->gp_idx - 1] = 1;
	mcp->txbuf[mcp->gp_idx] = !!value;

	mutex_lock(&mcp->lock);
	mcp_send_data_req_status(mcp, mcp->txbuf, 18);
	mutex_unlock(&mcp->lock);
}

static int mcp_gpio_dir_set(struct mcp2221 *mcp,
				unsigned int offset, u8 val)
{
	memset(mcp->txbuf, 0, 18);
	mcp->txbuf[0] = MCP2221_GPIO_SET;

	mcp->gp_idx = offsetof(struct mcp_set_gpio, gpio[offset].direction);

	mcp->txbuf[mcp->gp_idx - 1] = 1;
	mcp->txbuf[mcp->gp_idx] = val;

	return mcp_send_data_req_status(mcp, mcp->txbuf, 18);
}

static int mcp_gpio_direction_input(struct gpio_chip *gc,
				unsigned int offset)
{
	int ret;
	struct mcp2221 *mcp = gpiochip_get_data(gc);

	mutex_lock(&mcp->lock);
	ret = mcp_gpio_dir_set(mcp, offset, MCP2221_DIR_IN);
	mutex_unlock(&mcp->lock);

	return ret;
}

static int mcp_gpio_direction_output(struct gpio_chip *gc,
				unsigned int offset, int value)
{
	int ret;
	struct mcp2221 *mcp = gpiochip_get_data(gc);

	mutex_lock(&mcp->lock);
	ret = mcp_gpio_dir_set(mcp, offset, MCP2221_DIR_OUT);
	mutex_unlock(&mcp->lock);

	/* Can't configure as output, bailout early */
	if (ret)
		return ret;

	mcp_gpio_set(gc, offset, value);

	return 0;
}

static int mcp_gpio_get_direction(struct gpio_chip *gc,
				unsigned int offset)
{
	int ret;
	struct mcp2221 *mcp = gpiochip_get_data(gc);

	mcp->txbuf[0] = MCP2221_GPIO_GET;

	mcp->gp_idx = offsetof(struct mcp_get_gpio, gpio[offset].direction);

	mutex_lock(&mcp->lock);
	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
	mutex_unlock(&mcp->lock);

	if (ret)
		return ret;

	if (mcp->gpio_dir == MCP2221_DIR_IN)
		return GPIO_LINE_DIRECTION_IN;

	return GPIO_LINE_DIRECTION_OUT;
}

/* Gives current state of i2c engine inside mcp2221 */
static int mcp_get_i2c_eng_state(struct mcp2221 *mcp,
				u8 *data, u8 idx)
{
	int ret;

	switch (data[idx]) {
	case MCP2221_I2C_WRADDRL_NACK:
	case MCP2221_I2C_WRADDRL_SEND:
		ret = -ENXIO;
		break;
	case MCP2221_I2C_START_TOUT:
	case MCP2221_I2C_STOP_TOUT:
	case MCP2221_I2C_WRADDRL_TOUT:
	case MCP2221_I2C_WRDATA_TOUT:
		ret = -ETIMEDOUT;
		break;
	case MCP2221_I2C_ENG_BUSY:
		ret = -EAGAIN;
		break;
	case MCP2221_SUCCESS:
		ret = 0x00;
		break;
	default:
		ret = -EIO;
	}

	return ret;
}

/*
 * MCP2221 uses interrupt endpoint for input reports. This function
 * is called by HID layer when it receives i/p report from mcp2221,
 * which is actually a response to the previously sent command.
 *
 * MCP2221A firmware specific return codes are parsed and 0 or
 * appropriate negative error code is returned. Delayed response
 * results in timeout error and stray reponses results in -EIO.
 */
static int mcp2221_raw_event(struct hid_device *hdev,
				struct hid_report *report, u8 *data, int size)
{
	u8 *buf;
	struct mcp2221 *mcp = hid_get_drvdata(hdev);

	switch (data[0]) {

	case MCP2221_I2C_WR_DATA:
	case MCP2221_I2C_WR_NO_STOP:
	case MCP2221_I2C_RD_DATA:
	case MCP2221_I2C_RD_RPT_START:
		switch (data[1]) {
		case MCP2221_SUCCESS:
			mcp->status = 0;
			break;
		default:
			mcp->status = mcp_get_i2c_eng_state(mcp, data, 2);
		}
		complete(&mcp->wait_in_report);
		break;

	case MCP2221_I2C_PARAM_OR_STATUS:
		switch (data[1]) {
		case MCP2221_SUCCESS:
			if ((mcp->txbuf[3] == MCP2221_I2C_SET_SPEED) &&
				(data[3] != MCP2221_I2C_SET_SPEED)) {
				mcp->status = -EAGAIN;
				break;
			}
			if (data[20] & MCP2221_I2C_MASK_ADDR_NACK) {
				mcp->status = -ENXIO;
				break;
			}
			mcp->status = mcp_get_i2c_eng_state(mcp, data, 8);
			break;
		default:
			mcp->status = -EIO;
		}
		complete(&mcp->wait_in_report);
		break;

	case MCP2221_I2C_GET_DATA:
		switch (data[1]) {
		case MCP2221_SUCCESS:
			if (data[2] == MCP2221_I2C_ADDR_NACK) {
				mcp->status = -ENXIO;
				break;
			}
			if (!mcp_get_i2c_eng_state(mcp, data, 2)
				&& (data[3] == 0)) {
				mcp->status = 0;
				break;
			}
			if (data[3] == 127) {
				mcp->status = -EIO;
				break;
			}
			if (data[2] == MCP2221_I2C_READ_COMPL) {
				buf = mcp->rxbuf;
				memcpy(&buf[mcp->rxbuf_idx], &data[4], data[3]);
				mcp->rxbuf_idx = mcp->rxbuf_idx + data[3];
				mcp->status = 0;
				break;
			}
			mcp->status = -EIO;
			break;
		default:
			mcp->status = -EIO;
		}
		complete(&mcp->wait_in_report);
		break;

	case MCP2221_GPIO_GET:
		switch (data[1]) {
		case MCP2221_SUCCESS:
			if ((data[mcp->gp_idx] == MCP2221_ALT_F_NOT_GPIOV) ||
				(data[mcp->gp_idx + 1] == MCP2221_ALT_F_NOT_GPIOD)) {
				mcp->status = -ENOENT;
			} else {
				mcp->status = !!data[mcp->gp_idx];
				mcp->gpio_dir = data[mcp->gp_idx + 1];
			}
			break;
		default:
			mcp->status = -EAGAIN;
		}
		complete(&mcp->wait_in_report);
		break;

	case MCP2221_GPIO_SET:
		switch (data[1]) {
		case MCP2221_SUCCESS:
			if ((data[mcp->gp_idx] == MCP2221_ALT_F_NOT_GPIOV) ||
				(data[mcp->gp_idx - 1] == MCP2221_ALT_F_NOT_GPIOV)) {
				mcp->status = -ENOENT;
			} else {
				mcp->status = 0;
			}
			break;
		default:
			mcp->status = -EAGAIN;
		}
		complete(&mcp->wait_in_report);
		break;

	default:
		mcp->status = -EIO;
		complete(&mcp->wait_in_report);
	}

	return 1;
}

static int mcp2221_probe(struct hid_device *hdev,
					const struct hid_device_id *id)
{
	int ret;
	struct mcp2221 *mcp;

	mcp = devm_kzalloc(&hdev->dev, sizeof(*mcp), GFP_KERNEL);
	if (!mcp)
		return -ENOMEM;

	ret = hid_parse(hdev);
	if (ret) {
		hid_err(hdev, "can't parse reports\n");
		return ret;
	}

	/*
	 * This driver uses the .raw_event callback and therefore does not need any
	 * HID_CONNECT_xxx flags.
	 */
	ret = hid_hw_start(hdev, 0);
	if (ret) {
		hid_err(hdev, "can't start hardware\n");
		return ret;
	}

	hid_info(hdev, "USB HID v%x.%02x Device [%s] on %s\n", hdev->version >> 8,
			hdev->version & 0xff, hdev->name, hdev->phys);

	ret = hid_hw_open(hdev);
	if (ret) {
		hid_err(hdev, "can't open device\n");
		goto err_hstop;
	}

	mutex_init(&mcp->lock);
	init_completion(&mcp->wait_in_report);
	hid_set_drvdata(hdev, mcp);
	mcp->hdev = hdev;

	/* Set I2C bus clock diviser */
	if (i2c_clk_freq > 400)
		i2c_clk_freq = 400;
	if (i2c_clk_freq < 50)
		i2c_clk_freq = 50;
	mcp->cur_i2c_clk_div = (12000000 / (i2c_clk_freq * 1000)) - 3;

	mcp->adapter.owner = THIS_MODULE;
	mcp->adapter.class = I2C_CLASS_HWMON;
	mcp->adapter.algo = &mcp_i2c_algo;
	mcp->adapter.retries = 1;
	mcp->adapter.dev.parent = &hdev->dev;
	snprintf(mcp->adapter.name, sizeof(mcp->adapter.name),
			"MCP2221 usb-i2c bridge");

	ret = i2c_add_adapter(&mcp->adapter);
	if (ret) {
		hid_err(hdev, "can't add usb-i2c adapter: %d\n", ret);
		goto err_i2c;
	}
	i2c_set_adapdata(&mcp->adapter, mcp);

	/* Setup GPIO chip */
	mcp->gc = devm_kzalloc(&hdev->dev, sizeof(*mcp->gc), GFP_KERNEL);
	if (!mcp->gc) {
		ret = -ENOMEM;
		goto err_gc;
	}

	mcp->gc->label = "mcp2221_gpio";
	mcp->gc->direction_input = mcp_gpio_direction_input;
	mcp->gc->direction_output = mcp_gpio_direction_output;
	mcp->gc->get_direction = mcp_gpio_get_direction;
	mcp->gc->set = mcp_gpio_set;
	mcp->gc->get = mcp_gpio_get;
	mcp->gc->ngpio = MCP_NGPIO;
	mcp->gc->base = -1;
	mcp->gc->can_sleep = 1;
	mcp->gc->parent = &hdev->dev;

	ret = devm_gpiochip_add_data(&hdev->dev, mcp->gc, mcp);
	if (ret)
		goto err_gc;

	return 0;

err_gc:
	i2c_del_adapter(&mcp->adapter);
err_i2c:
	hid_hw_close(mcp->hdev);
err_hstop:
	hid_hw_stop(mcp->hdev);
	return ret;
}

static void mcp2221_remove(struct hid_device *hdev)
{
	struct mcp2221 *mcp = hid_get_drvdata(hdev);

	i2c_del_adapter(&mcp->adapter);
	hid_hw_close(mcp->hdev);
	hid_hw_stop(mcp->hdev);
}

static const struct hid_device_id mcp2221_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_MCP2221) },
	{ }
};
MODULE_DEVICE_TABLE(hid, mcp2221_devices);

static struct hid_driver mcp2221_driver = {
	.name		= "mcp2221",
	.id_table	= mcp2221_devices,
	.probe		= mcp2221_probe,
	.remove		= mcp2221_remove,
	.raw_event	= mcp2221_raw_event,
};

/* Register with HID core */
module_hid_driver(mcp2221_driver);

MODULE_AUTHOR("Rishi Gupta <gupt21@gmail.com>");
MODULE_DESCRIPTION("MCP2221 Microchip HID USB to I2C master bridge");
MODULE_LICENSE("GPL v2");