summaryrefslogtreecommitdiffstats
path: root/drivers/char/tpm/tpm_i2c_nuvoton.c
blob: caa86b19c76dd7007a3975756dec8fe069a31db3 (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
 /******************************************************************************
 * Nuvoton TPM I2C Device Driver Interface for WPCT301/NPCT501/NPCT6XX,
 * based on the TCG TPM Interface Spec version 1.2.
 * Specifications at www.trustedcomputinggroup.org
 *
 * Copyright (C) 2011, Nuvoton Technology Corporation.
 *  Dan Morav <dan.morav@nuvoton.com>
 * Copyright (C) 2013, Obsidian Research Corp.
 *  Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/>.
 *
 * Nuvoton contact information: APC.Support@nuvoton.com
 *****************************************************************************/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/i2c.h>
#include <linux/of_device.h>
#include "tpm.h"

/* I2C interface offsets */
#define TPM_STS                0x00
#define TPM_BURST_COUNT        0x01
#define TPM_DATA_FIFO_W        0x20
#define TPM_DATA_FIFO_R        0x40
#define TPM_VID_DID_RID        0x60
/* TPM command header size */
#define TPM_HEADER_SIZE        10
#define TPM_RETRY      5
/*
 * I2C bus device maximum buffer size w/o counting I2C address or command
 * i.e. max size required for I2C write is 34 = addr, command, 32 bytes data
 */
#define TPM_I2C_MAX_BUF_SIZE           32
#define TPM_I2C_RETRY_COUNT            32
#define TPM_I2C_BUS_DELAY              1000      	/* usec */
#define TPM_I2C_RETRY_DELAY_SHORT      (2 * 1000)	/* usec */
#define TPM_I2C_RETRY_DELAY_LONG       (10 * 1000) 	/* usec */
#define TPM_I2C_DELAY_RANGE            300		/* usec */

#define OF_IS_TPM2 ((void *)1)
#define I2C_IS_TPM2 1

struct priv_data {
	int irq;
	unsigned int intrs;
	wait_queue_head_t read_queue;
};

static s32 i2c_nuvoton_read_buf(struct i2c_client *client, u8 offset, u8 size,
				u8 *data)
{
	s32 status;

	status = i2c_smbus_read_i2c_block_data(client, offset, size, data);
	dev_dbg(&client->dev,
		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
		offset, size, (int)size, data, status);
	return status;
}

static s32 i2c_nuvoton_write_buf(struct i2c_client *client, u8 offset, u8 size,
				 u8 *data)
{
	s32 status;

	status = i2c_smbus_write_i2c_block_data(client, offset, size, data);
	dev_dbg(&client->dev,
		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
		offset, size, (int)size, data, status);
	return status;
}

#define TPM_STS_VALID          0x80
#define TPM_STS_COMMAND_READY  0x40
#define TPM_STS_GO             0x20
#define TPM_STS_DATA_AVAIL     0x10
#define TPM_STS_EXPECT         0x08
#define TPM_STS_RESPONSE_RETRY 0x02
#define TPM_STS_ERR_VAL        0x07    /* bit2...bit0 reads always 0 */

#define TPM_I2C_SHORT_TIMEOUT  750     /* ms */
#define TPM_I2C_LONG_TIMEOUT   2000    /* 2 sec */

/* read TPM_STS register */
static u8 i2c_nuvoton_read_status(struct tpm_chip *chip)
{
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	s32 status;
	u8 data;

	status = i2c_nuvoton_read_buf(client, TPM_STS, 1, &data);
	if (status <= 0) {
		dev_err(&chip->dev, "%s() error return %d\n", __func__,
			status);
		data = TPM_STS_ERR_VAL;
	}

	return data;
}

/* write byte to TPM_STS register */
static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
{
	s32 status;
	int i;

	/* this causes the current command to be aborted */
	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
		if (status < 0)
			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
				     + TPM_I2C_DELAY_RANGE);
	}
	return status;
}

/* write commandReady to TPM_STS register */
static void i2c_nuvoton_ready(struct tpm_chip *chip)
{
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	s32 status;

	/* this causes the current command to be aborted */
	status = i2c_nuvoton_write_status(client, TPM_STS_COMMAND_READY);
	if (status < 0)
		dev_err(&chip->dev,
			"%s() fail to write TPM_STS.commandReady\n", __func__);
}

/* read burstCount field from TPM_STS register
 * return -1 on fail to read */
static int i2c_nuvoton_get_burstcount(struct i2c_client *client,
				      struct tpm_chip *chip)
{
	unsigned long stop = jiffies + chip->timeout_d;
	s32 status;
	int burst_count = -1;
	u8 data;

	/* wait for burstcount to be non-zero */
	do {
		/* in I2C burstCount is 1 byte */
		status = i2c_nuvoton_read_buf(client, TPM_BURST_COUNT, 1,
					      &data);
		if (status > 0 && data > 0) {
			burst_count = min_t(u8, TPM_I2C_MAX_BUF_SIZE, data);
			break;
		}
		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
			     + TPM_I2C_DELAY_RANGE);
	} while (time_before(jiffies, stop));

	return burst_count;
}

/*
 * WPCT301/NPCT501/NPCT6XX SINT# supports only dataAvail
 * any call to this function which is not waiting for dataAvail will
 * set queue to NULL to avoid waiting for interrupt
 */
static bool i2c_nuvoton_check_status(struct tpm_chip *chip, u8 mask, u8 value)
{
	u8 status = i2c_nuvoton_read_status(chip);
	return (status != TPM_STS_ERR_VAL) && ((status & mask) == value);
}

static int i2c_nuvoton_wait_for_stat(struct tpm_chip *chip, u8 mask, u8 value,
				     u32 timeout, wait_queue_head_t *queue)
{
	if ((chip->flags & TPM_CHIP_FLAG_IRQ) && queue) {
		s32 rc;
		struct priv_data *priv = dev_get_drvdata(&chip->dev);
		unsigned int cur_intrs = priv->intrs;

		enable_irq(priv->irq);
		rc = wait_event_interruptible_timeout(*queue,
						      cur_intrs != priv->intrs,
						      timeout);
		if (rc > 0)
			return 0;
		/* At this point we know that the SINT pin is asserted, so we
		 * do not need to do i2c_nuvoton_check_status */
	} else {
		unsigned long ten_msec, stop;
		bool status_valid;

		/* check current status */
		status_valid = i2c_nuvoton_check_status(chip, mask, value);
		if (status_valid)
			return 0;

		/* use polling to wait for the event */
		ten_msec = jiffies + usecs_to_jiffies(TPM_I2C_RETRY_DELAY_LONG);
		stop = jiffies + timeout;
		do {
			if (time_before(jiffies, ten_msec))
				usleep_range(TPM_I2C_RETRY_DELAY_SHORT,
					     TPM_I2C_RETRY_DELAY_SHORT
					     + TPM_I2C_DELAY_RANGE);
			else
				usleep_range(TPM_I2C_RETRY_DELAY_LONG,
					     TPM_I2C_RETRY_DELAY_LONG
					     + TPM_I2C_DELAY_RANGE);
			status_valid = i2c_nuvoton_check_status(chip, mask,
								value);
			if (status_valid)
				return 0;
		} while (time_before(jiffies, stop));
	}
	dev_err(&chip->dev, "%s(%02x, %02x) -> timeout\n", __func__, mask,
		value);
	return -ETIMEDOUT;
}

/* wait for dataAvail field to be set in the TPM_STS register */
static int i2c_nuvoton_wait_for_data_avail(struct tpm_chip *chip, u32 timeout,
					   wait_queue_head_t *queue)
{
	return i2c_nuvoton_wait_for_stat(chip,
					 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
					 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
					 timeout, queue);
}

/* Read @count bytes into @buf from TPM_RD_FIFO register */
static int i2c_nuvoton_recv_data(struct i2c_client *client,
				 struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	s32 rc;
	int burst_count, bytes2read, size = 0;

	while (size < count &&
	       i2c_nuvoton_wait_for_data_avail(chip,
					       chip->timeout_c,
					       &priv->read_queue) == 0) {
		burst_count = i2c_nuvoton_get_burstcount(client, chip);
		if (burst_count < 0) {
			dev_err(&chip->dev,
				"%s() fail to read burstCount=%d\n", __func__,
				burst_count);
			return -EIO;
		}
		bytes2read = min_t(size_t, burst_count, count - size);
		rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_R,
					  bytes2read, &buf[size]);
		if (rc < 0) {
			dev_err(&chip->dev,
				"%s() fail on i2c_nuvoton_read_buf()=%d\n",
				__func__, rc);
			return -EIO;
		}
		dev_dbg(&chip->dev, "%s(%d):", __func__, bytes2read);
		size += bytes2read;
	}

	return size;
}

/* Read TPM command results */
static int i2c_nuvoton_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	struct device *dev = chip->dev.parent;
	struct i2c_client *client = to_i2c_client(dev);
	s32 rc;
	int status;
	int burst_count;
	int retries;
	int size = 0;
	u32 expected;

	if (count < TPM_HEADER_SIZE) {
		i2c_nuvoton_ready(chip);    /* return to idle */
		dev_err(dev, "%s() count < header size\n", __func__);
		return -EIO;
	}
	for (retries = 0; retries < TPM_RETRY; retries++) {
		if (retries > 0) {
			/* if this is not the first trial, set responseRetry */
			i2c_nuvoton_write_status(client,
						 TPM_STS_RESPONSE_RETRY);
		}
		/*
		 * read first available (> 10 bytes), including:
		 * tag, paramsize, and result
		 */
		status = i2c_nuvoton_wait_for_data_avail(
			chip, chip->timeout_c, &priv->read_queue);
		if (status != 0) {
			dev_err(dev, "%s() timeout on dataAvail\n", __func__);
			size = -ETIMEDOUT;
			continue;
		}
		burst_count = i2c_nuvoton_get_burstcount(client, chip);
		if (burst_count < 0) {
			dev_err(dev, "%s() fail to get burstCount\n", __func__);
			size = -EIO;
			continue;
		}
		size = i2c_nuvoton_recv_data(client, chip, buf,
					     burst_count);
		if (size < TPM_HEADER_SIZE) {
			dev_err(dev, "%s() fail to read header\n", __func__);
			size = -EIO;
			continue;
		}
		/*
		 * convert number of expected bytes field from big endian 32 bit
		 * to machine native
		 */
		expected = be32_to_cpu(*(__be32 *) (buf + 2));
		if (expected > count || expected < size) {
			dev_err(dev, "%s() expected > count\n", __func__);
			size = -EIO;
			continue;
		}
		rc = i2c_nuvoton_recv_data(client, chip, &buf[size],
					   expected - size);
		size += rc;
		if (rc < 0 || size < expected) {
			dev_err(dev, "%s() fail to read remainder of result\n",
				__func__);
			size = -EIO;
			continue;
		}
		if (i2c_nuvoton_wait_for_stat(
			    chip, TPM_STS_VALID | TPM_STS_DATA_AVAIL,
			    TPM_STS_VALID, chip->timeout_c,
			    NULL)) {
			dev_err(dev, "%s() error left over data\n", __func__);
			size = -ETIMEDOUT;
			continue;
		}
		break;
	}
	i2c_nuvoton_ready(chip);
	dev_dbg(&chip->dev, "%s() -> %d\n", __func__, size);
	return size;
}

/*
 * Send TPM command.
 *
 * If interrupts are used (signaled by an irq set in the vendor structure)
 * tpm.c can skip polling for the data to be available as the interrupt is
 * waited for here
 */
static int i2c_nuvoton_send(struct tpm_chip *chip, u8 *buf, size_t len)
{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	struct device *dev = chip->dev.parent;
	struct i2c_client *client = to_i2c_client(dev);
	u32 ordinal;
	size_t count = 0;
	int burst_count, bytes2write, retries, rc = -EIO;

	for (retries = 0; retries < TPM_RETRY; retries++) {
		i2c_nuvoton_ready(chip);
		if (i2c_nuvoton_wait_for_stat(chip, TPM_STS_COMMAND_READY,
					      TPM_STS_COMMAND_READY,
					      chip->timeout_b, NULL)) {
			dev_err(dev, "%s() timeout on commandReady\n",
				__func__);
			rc = -EIO;
			continue;
		}
		rc = 0;
		while (count < len - 1) {
			burst_count = i2c_nuvoton_get_burstcount(client,
								 chip);
			if (burst_count < 0) {
				dev_err(dev, "%s() fail get burstCount\n",
					__func__);
				rc = -EIO;
				break;
			}
			bytes2write = min_t(size_t, burst_count,
					    len - 1 - count);
			rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W,
						   bytes2write, &buf[count]);
			if (rc < 0) {
				dev_err(dev, "%s() fail i2cWriteBuf\n",
					__func__);
				break;
			}
			dev_dbg(dev, "%s(%d):", __func__, bytes2write);
			count += bytes2write;
			rc = i2c_nuvoton_wait_for_stat(chip,
						       TPM_STS_VALID |
						       TPM_STS_EXPECT,
						       TPM_STS_VALID |
						       TPM_STS_EXPECT,
						       chip->timeout_c,
						       NULL);
			if (rc < 0) {
				dev_err(dev, "%s() timeout on Expect\n",
					__func__);
				rc = -ETIMEDOUT;
				break;
			}
		}
		if (rc < 0)
			continue;

		/* write last byte */
		rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W, 1,
					   &buf[count]);
		if (rc < 0) {
			dev_err(dev, "%s() fail to write last byte\n",
				__func__);
			rc = -EIO;
			continue;
		}
		dev_dbg(dev, "%s(last): %02x", __func__, buf[count]);
		rc = i2c_nuvoton_wait_for_stat(chip,
					       TPM_STS_VALID | TPM_STS_EXPECT,
					       TPM_STS_VALID,
					       chip->timeout_c, NULL);
		if (rc) {
			dev_err(dev, "%s() timeout on Expect to clear\n",
				__func__);
			rc = -ETIMEDOUT;
			continue;
		}
		break;
	}
	if (rc < 0) {
		/* retries == TPM_RETRY */
		i2c_nuvoton_ready(chip);
		return rc;
	}
	/* execute the TPM command */
	rc = i2c_nuvoton_write_status(client, TPM_STS_GO);
	if (rc < 0) {
		dev_err(dev, "%s() fail to write Go\n", __func__);
		i2c_nuvoton_ready(chip);
		return rc;
	}
	ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
	rc = i2c_nuvoton_wait_for_data_avail(chip,
					     tpm_calc_ordinal_duration(chip,
								       ordinal),
					     &priv->read_queue);
	if (rc) {
		dev_err(dev, "%s() timeout command duration\n", __func__);
		i2c_nuvoton_ready(chip);
		return rc;
	}

	dev_dbg(dev, "%s() -> %zd\n", __func__, len);
	return len;
}

static bool i2c_nuvoton_req_canceled(struct tpm_chip *chip, u8 status)
{
	return (status == TPM_STS_COMMAND_READY);
}

static const struct tpm_class_ops tpm_i2c = {
	.flags = TPM_OPS_AUTO_STARTUP,
	.status = i2c_nuvoton_read_status,
	.recv = i2c_nuvoton_recv,
	.send = i2c_nuvoton_send,
	.cancel = i2c_nuvoton_ready,
	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
	.req_canceled = i2c_nuvoton_req_canceled,
};

/* The only purpose for the handler is to signal to any waiting threads that
 * the interrupt is currently being asserted. The driver does not do any
 * processing triggered by interrupts, and the chip provides no way to mask at
 * the source (plus that would be slow over I2C). Run the IRQ as a one-shot,
 * this means it cannot be shared. */
static irqreturn_t i2c_nuvoton_int_handler(int dummy, void *dev_id)
{
	struct tpm_chip *chip = dev_id;
	struct priv_data *priv = dev_get_drvdata(&chip->dev);

	priv->intrs++;
	wake_up(&priv->read_queue);
	disable_irq_nosync(priv->irq);
	return IRQ_HANDLED;
}

static int get_vid(struct i2c_client *client, u32 *res)
{
	static const u8 vid_did_rid_value[] = { 0x50, 0x10, 0xfe };
	u32 temp;
	s32 rc;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -ENODEV;
	rc = i2c_nuvoton_read_buf(client, TPM_VID_DID_RID, 4, (u8 *)&temp);
	if (rc < 0)
		return rc;

	/* check WPCT301 values - ignore RID */
	if (memcmp(&temp, vid_did_rid_value, sizeof(vid_did_rid_value))) {
		/*
		 * f/w rev 2.81 has an issue where the VID_DID_RID is not
		 * reporting the right value. so give it another chance at
		 * offset 0x20 (FIFO_W).
		 */
		rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_W, 4,
					  (u8 *) (&temp));
		if (rc < 0)
			return rc;

		/* check WPCT301 values - ignore RID */
		if (memcmp(&temp, vid_did_rid_value,
			   sizeof(vid_did_rid_value)))
			return -ENODEV;
	}

	*res = temp;
	return 0;
}

static int i2c_nuvoton_probe(struct i2c_client *client,
			     const struct i2c_device_id *id)
{
	int rc;
	struct tpm_chip *chip;
	struct device *dev = &client->dev;
	struct priv_data *priv;
	u32 vid = 0;

	rc = get_vid(client, &vid);
	if (rc)
		return rc;

	dev_info(dev, "VID: %04X DID: %02X RID: %02X\n", (u16) vid,
		 (u8) (vid >> 16), (u8) (vid >> 24));

	chip = tpmm_chip_alloc(dev, &tpm_i2c);
	if (IS_ERR(chip))
		return PTR_ERR(chip);

	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	if (dev->of_node) {
		const struct of_device_id *of_id;

		of_id = of_match_device(dev->driver->of_match_table, dev);
		if (of_id && of_id->data == OF_IS_TPM2)
			chip->flags |= TPM_CHIP_FLAG_TPM2;
	} else
		if (id->driver_data == I2C_IS_TPM2)
			chip->flags |= TPM_CHIP_FLAG_TPM2;

	init_waitqueue_head(&priv->read_queue);

	/* Default timeouts */
	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);

	dev_set_drvdata(&chip->dev, priv);

	/*
	 * I2C intfcaps (interrupt capabilitieis) in the chip are hard coded to:
	 *   TPM_INTF_INT_LEVEL_LOW | TPM_INTF_DATA_AVAIL_INT
	 * The IRQ should be set in the i2c_board_info (which is done
	 * automatically in of_i2c_register_devices, for device tree users */
	priv->irq = client->irq;
	if (client->irq) {
		dev_dbg(dev, "%s() priv->irq\n", __func__);
		rc = devm_request_irq(dev, client->irq,
				      i2c_nuvoton_int_handler,
				      IRQF_TRIGGER_LOW,
				      dev_name(&chip->dev),
				      chip);
		if (rc) {
			dev_err(dev, "%s() Unable to request irq: %d for use\n",
				__func__, priv->irq);
			priv->irq = 0;
		} else {
			chip->flags |= TPM_CHIP_FLAG_IRQ;
			/* Clear any pending interrupt */
			i2c_nuvoton_ready(chip);
			/* - wait for TPM_STS==0xA0 (stsValid, commandReady) */
			rc = i2c_nuvoton_wait_for_stat(chip,
						       TPM_STS_COMMAND_READY,
						       TPM_STS_COMMAND_READY,
						       chip->timeout_b,
						       NULL);
			if (rc == 0) {
				/*
				 * TIS is in ready state
				 * write dummy byte to enter reception state
				 * TPM_DATA_FIFO_W <- rc (0)
				 */
				rc = i2c_nuvoton_write_buf(client,
							   TPM_DATA_FIFO_W,
							   1, (u8 *) (&rc));
				if (rc < 0)
					return rc;
				/* TPM_STS <- 0x40 (commandReady) */
				i2c_nuvoton_ready(chip);
			} else {
				/*
				 * timeout_b reached - command was
				 * aborted. TIS should now be in idle state -
				 * only TPM_STS_VALID should be set
				 */
				if (i2c_nuvoton_read_status(chip) !=
				    TPM_STS_VALID)
					return -EIO;
			}
		}
	}

	return tpm_chip_register(chip);
}

static int i2c_nuvoton_remove(struct i2c_client *client)
{
	struct tpm_chip *chip = i2c_get_clientdata(client);

	tpm_chip_unregister(chip);
	return 0;
}

static const struct i2c_device_id i2c_nuvoton_id[] = {
	{"tpm_i2c_nuvoton"},
	{"tpm2_i2c_nuvoton", .driver_data = I2C_IS_TPM2},
	{}
};
MODULE_DEVICE_TABLE(i2c, i2c_nuvoton_id);

#ifdef CONFIG_OF
static const struct of_device_id i2c_nuvoton_of_match[] = {
	{.compatible = "nuvoton,npct501"},
	{.compatible = "winbond,wpct301"},
	{.compatible = "nuvoton,npct601", .data = OF_IS_TPM2},
	{},
};
MODULE_DEVICE_TABLE(of, i2c_nuvoton_of_match);
#endif

static SIMPLE_DEV_PM_OPS(i2c_nuvoton_pm_ops, tpm_pm_suspend, tpm_pm_resume);

static struct i2c_driver i2c_nuvoton_driver = {
	.id_table = i2c_nuvoton_id,
	.probe = i2c_nuvoton_probe,
	.remove = i2c_nuvoton_remove,
	.driver = {
		.name = "tpm_i2c_nuvoton",
		.pm = &i2c_nuvoton_pm_ops,
		.of_match_table = of_match_ptr(i2c_nuvoton_of_match),
	},
};

module_i2c_driver(i2c_nuvoton_driver);

MODULE_AUTHOR("Dan Morav (dan.morav@nuvoton.com)");
MODULE_DESCRIPTION("Nuvoton TPM I2C Driver");
MODULE_LICENSE("GPL");