1  /******************************************************************************
2  * Nuvoton TPM I2C Device Driver Interface for WPCT301/NPCT501/NPCT6XX,
3  * based on the TCG TPM Interface Spec version 1.2.
4  * Specifications at www.trustedcomputinggroup.org
5  *
6  * Copyright (C) 2011, Nuvoton Technology Corporation.
7  *  Dan Morav <dan.morav@nuvoton.com>
8  * Copyright (C) 2013, Obsidian Research Corp.
9  *  Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
10  *
11  * This program is free software: you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation, either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program.  If not, see http://www.gnu.org/licenses/>.
23  *
24  * Nuvoton contact information: APC.Support@nuvoton.com
25  *****************************************************************************/
26 
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/moduleparam.h>
30 #include <linux/slab.h>
31 #include <linux/interrupt.h>
32 #include <linux/wait.h>
33 #include <linux/i2c.h>
34 #include <linux/of_device.h>
35 #include "tpm.h"
36 
37 /* I2C interface offsets */
38 #define TPM_STS                0x00
39 #define TPM_BURST_COUNT        0x01
40 #define TPM_DATA_FIFO_W        0x20
41 #define TPM_DATA_FIFO_R        0x40
42 #define TPM_VID_DID_RID        0x60
43 /* TPM command header size */
44 #define TPM_HEADER_SIZE        10
45 #define TPM_RETRY      5
46 /*
47  * I2C bus device maximum buffer size w/o counting I2C address or command
48  * i.e. max size required for I2C write is 34 = addr, command, 32 bytes data
49  */
50 #define TPM_I2C_MAX_BUF_SIZE           32
51 #define TPM_I2C_RETRY_COUNT            32
52 #define TPM_I2C_BUS_DELAY              1000      	/* usec */
53 #define TPM_I2C_RETRY_DELAY_SHORT      (2 * 1000)	/* usec */
54 #define TPM_I2C_RETRY_DELAY_LONG       (10 * 1000) 	/* usec */
55 #define TPM_I2C_DELAY_RANGE            300		/* usec */
56 
57 #define OF_IS_TPM2 ((void *)1)
58 #define I2C_IS_TPM2 1
59 
60 struct priv_data {
61 	int irq;
62 	unsigned int intrs;
63 	wait_queue_head_t read_queue;
64 };
65 
66 static s32 i2c_nuvoton_read_buf(struct i2c_client *client, u8 offset, u8 size,
67 				u8 *data)
68 {
69 	s32 status;
70 
71 	status = i2c_smbus_read_i2c_block_data(client, offset, size, data);
72 	dev_dbg(&client->dev,
73 		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
74 		offset, size, (int)size, data, status);
75 	return status;
76 }
77 
78 static s32 i2c_nuvoton_write_buf(struct i2c_client *client, u8 offset, u8 size,
79 				 u8 *data)
80 {
81 	s32 status;
82 
83 	status = i2c_smbus_write_i2c_block_data(client, offset, size, data);
84 	dev_dbg(&client->dev,
85 		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
86 		offset, size, (int)size, data, status);
87 	return status;
88 }
89 
90 #define TPM_STS_VALID          0x80
91 #define TPM_STS_COMMAND_READY  0x40
92 #define TPM_STS_GO             0x20
93 #define TPM_STS_DATA_AVAIL     0x10
94 #define TPM_STS_EXPECT         0x08
95 #define TPM_STS_RESPONSE_RETRY 0x02
96 #define TPM_STS_ERR_VAL        0x07    /* bit2...bit0 reads always 0 */
97 
98 #define TPM_I2C_SHORT_TIMEOUT  750     /* ms */
99 #define TPM_I2C_LONG_TIMEOUT   2000    /* 2 sec */
100 
101 /* read TPM_STS register */
102 static u8 i2c_nuvoton_read_status(struct tpm_chip *chip)
103 {
104 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
105 	s32 status;
106 	u8 data;
107 
108 	status = i2c_nuvoton_read_buf(client, TPM_STS, 1, &data);
109 	if (status <= 0) {
110 		dev_err(&chip->dev, "%s() error return %d\n", __func__,
111 			status);
112 		data = TPM_STS_ERR_VAL;
113 	}
114 
115 	return data;
116 }
117 
118 /* write byte to TPM_STS register */
119 static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
120 {
121 	s32 status;
122 	int i;
123 
124 	/* this causes the current command to be aborted */
125 	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
126 		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
127 		if (status < 0)
128 			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
129 				     + TPM_I2C_DELAY_RANGE);
130 	}
131 	return status;
132 }
133 
134 /* write commandReady to TPM_STS register */
135 static void i2c_nuvoton_ready(struct tpm_chip *chip)
136 {
137 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
138 	s32 status;
139 
140 	/* this causes the current command to be aborted */
141 	status = i2c_nuvoton_write_status(client, TPM_STS_COMMAND_READY);
142 	if (status < 0)
143 		dev_err(&chip->dev,
144 			"%s() fail to write TPM_STS.commandReady\n", __func__);
145 }
146 
147 /* read burstCount field from TPM_STS register
148  * return -1 on fail to read */
149 static int i2c_nuvoton_get_burstcount(struct i2c_client *client,
150 				      struct tpm_chip *chip)
151 {
152 	unsigned long stop = jiffies + chip->timeout_d;
153 	s32 status;
154 	int burst_count = -1;
155 	u8 data;
156 
157 	/* wait for burstcount to be non-zero */
158 	do {
159 		/* in I2C burstCount is 1 byte */
160 		status = i2c_nuvoton_read_buf(client, TPM_BURST_COUNT, 1,
161 					      &data);
162 		if (status > 0 && data > 0) {
163 			burst_count = min_t(u8, TPM_I2C_MAX_BUF_SIZE, data);
164 			break;
165 		}
166 		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
167 			     + TPM_I2C_DELAY_RANGE);
168 	} while (time_before(jiffies, stop));
169 
170 	return burst_count;
171 }
172 
173 /*
174  * WPCT301/NPCT501/NPCT6XX SINT# supports only dataAvail
175  * any call to this function which is not waiting for dataAvail will
176  * set queue to NULL to avoid waiting for interrupt
177  */
178 static bool i2c_nuvoton_check_status(struct tpm_chip *chip, u8 mask, u8 value)
179 {
180 	u8 status = i2c_nuvoton_read_status(chip);
181 	return (status != TPM_STS_ERR_VAL) && ((status & mask) == value);
182 }
183 
184 static int i2c_nuvoton_wait_for_stat(struct tpm_chip *chip, u8 mask, u8 value,
185 				     u32 timeout, wait_queue_head_t *queue)
186 {
187 	if ((chip->flags & TPM_CHIP_FLAG_IRQ) && queue) {
188 		s32 rc;
189 		struct priv_data *priv = dev_get_drvdata(&chip->dev);
190 		unsigned int cur_intrs = priv->intrs;
191 
192 		enable_irq(priv->irq);
193 		rc = wait_event_interruptible_timeout(*queue,
194 						      cur_intrs != priv->intrs,
195 						      timeout);
196 		if (rc > 0)
197 			return 0;
198 		/* At this point we know that the SINT pin is asserted, so we
199 		 * do not need to do i2c_nuvoton_check_status */
200 	} else {
201 		unsigned long ten_msec, stop;
202 		bool status_valid;
203 
204 		/* check current status */
205 		status_valid = i2c_nuvoton_check_status(chip, mask, value);
206 		if (status_valid)
207 			return 0;
208 
209 		/* use polling to wait for the event */
210 		ten_msec = jiffies + usecs_to_jiffies(TPM_I2C_RETRY_DELAY_LONG);
211 		stop = jiffies + timeout;
212 		do {
213 			if (time_before(jiffies, ten_msec))
214 				usleep_range(TPM_I2C_RETRY_DELAY_SHORT,
215 					     TPM_I2C_RETRY_DELAY_SHORT
216 					     + TPM_I2C_DELAY_RANGE);
217 			else
218 				usleep_range(TPM_I2C_RETRY_DELAY_LONG,
219 					     TPM_I2C_RETRY_DELAY_LONG
220 					     + TPM_I2C_DELAY_RANGE);
221 			status_valid = i2c_nuvoton_check_status(chip, mask,
222 								value);
223 			if (status_valid)
224 				return 0;
225 		} while (time_before(jiffies, stop));
226 	}
227 	dev_err(&chip->dev, "%s(%02x, %02x) -> timeout\n", __func__, mask,
228 		value);
229 	return -ETIMEDOUT;
230 }
231 
232 /* wait for dataAvail field to be set in the TPM_STS register */
233 static int i2c_nuvoton_wait_for_data_avail(struct tpm_chip *chip, u32 timeout,
234 					   wait_queue_head_t *queue)
235 {
236 	return i2c_nuvoton_wait_for_stat(chip,
237 					 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
238 					 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
239 					 timeout, queue);
240 }
241 
242 /* Read @count bytes into @buf from TPM_RD_FIFO register */
243 static int i2c_nuvoton_recv_data(struct i2c_client *client,
244 				 struct tpm_chip *chip, u8 *buf, size_t count)
245 {
246 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
247 	s32 rc;
248 	int burst_count, bytes2read, size = 0;
249 
250 	while (size < count &&
251 	       i2c_nuvoton_wait_for_data_avail(chip,
252 					       chip->timeout_c,
253 					       &priv->read_queue) == 0) {
254 		burst_count = i2c_nuvoton_get_burstcount(client, chip);
255 		if (burst_count < 0) {
256 			dev_err(&chip->dev,
257 				"%s() fail to read burstCount=%d\n", __func__,
258 				burst_count);
259 			return -EIO;
260 		}
261 		bytes2read = min_t(size_t, burst_count, count - size);
262 		rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_R,
263 					  bytes2read, &buf[size]);
264 		if (rc < 0) {
265 			dev_err(&chip->dev,
266 				"%s() fail on i2c_nuvoton_read_buf()=%d\n",
267 				__func__, rc);
268 			return -EIO;
269 		}
270 		dev_dbg(&chip->dev, "%s(%d):", __func__, bytes2read);
271 		size += bytes2read;
272 	}
273 
274 	return size;
275 }
276 
277 /* Read TPM command results */
278 static int i2c_nuvoton_recv(struct tpm_chip *chip, u8 *buf, size_t count)
279 {
280 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
281 	struct device *dev = chip->dev.parent;
282 	struct i2c_client *client = to_i2c_client(dev);
283 	s32 rc;
284 	int expected, status, burst_count, retries, size = 0;
285 
286 	if (count < TPM_HEADER_SIZE) {
287 		i2c_nuvoton_ready(chip);    /* return to idle */
288 		dev_err(dev, "%s() count < header size\n", __func__);
289 		return -EIO;
290 	}
291 	for (retries = 0; retries < TPM_RETRY; retries++) {
292 		if (retries > 0) {
293 			/* if this is not the first trial, set responseRetry */
294 			i2c_nuvoton_write_status(client,
295 						 TPM_STS_RESPONSE_RETRY);
296 		}
297 		/*
298 		 * read first available (> 10 bytes), including:
299 		 * tag, paramsize, and result
300 		 */
301 		status = i2c_nuvoton_wait_for_data_avail(
302 			chip, chip->timeout_c, &priv->read_queue);
303 		if (status != 0) {
304 			dev_err(dev, "%s() timeout on dataAvail\n", __func__);
305 			size = -ETIMEDOUT;
306 			continue;
307 		}
308 		burst_count = i2c_nuvoton_get_burstcount(client, chip);
309 		if (burst_count < 0) {
310 			dev_err(dev, "%s() fail to get burstCount\n", __func__);
311 			size = -EIO;
312 			continue;
313 		}
314 		size = i2c_nuvoton_recv_data(client, chip, buf,
315 					     burst_count);
316 		if (size < TPM_HEADER_SIZE) {
317 			dev_err(dev, "%s() fail to read header\n", __func__);
318 			size = -EIO;
319 			continue;
320 		}
321 		/*
322 		 * convert number of expected bytes field from big endian 32 bit
323 		 * to machine native
324 		 */
325 		expected = be32_to_cpu(*(__be32 *) (buf + 2));
326 		if (expected > count) {
327 			dev_err(dev, "%s() expected > count\n", __func__);
328 			size = -EIO;
329 			continue;
330 		}
331 		rc = i2c_nuvoton_recv_data(client, chip, &buf[size],
332 					   expected - size);
333 		size += rc;
334 		if (rc < 0 || size < expected) {
335 			dev_err(dev, "%s() fail to read remainder of result\n",
336 				__func__);
337 			size = -EIO;
338 			continue;
339 		}
340 		if (i2c_nuvoton_wait_for_stat(
341 			    chip, TPM_STS_VALID | TPM_STS_DATA_AVAIL,
342 			    TPM_STS_VALID, chip->timeout_c,
343 			    NULL)) {
344 			dev_err(dev, "%s() error left over data\n", __func__);
345 			size = -ETIMEDOUT;
346 			continue;
347 		}
348 		break;
349 	}
350 	i2c_nuvoton_ready(chip);
351 	dev_dbg(&chip->dev, "%s() -> %d\n", __func__, size);
352 	return size;
353 }
354 
355 /*
356  * Send TPM command.
357  *
358  * If interrupts are used (signaled by an irq set in the vendor structure)
359  * tpm.c can skip polling for the data to be available as the interrupt is
360  * waited for here
361  */
362 static int i2c_nuvoton_send(struct tpm_chip *chip, u8 *buf, size_t len)
363 {
364 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
365 	struct device *dev = chip->dev.parent;
366 	struct i2c_client *client = to_i2c_client(dev);
367 	u32 ordinal;
368 	size_t count = 0;
369 	int burst_count, bytes2write, retries, rc = -EIO;
370 
371 	for (retries = 0; retries < TPM_RETRY; retries++) {
372 		i2c_nuvoton_ready(chip);
373 		if (i2c_nuvoton_wait_for_stat(chip, TPM_STS_COMMAND_READY,
374 					      TPM_STS_COMMAND_READY,
375 					      chip->timeout_b, NULL)) {
376 			dev_err(dev, "%s() timeout on commandReady\n",
377 				__func__);
378 			rc = -EIO;
379 			continue;
380 		}
381 		rc = 0;
382 		while (count < len - 1) {
383 			burst_count = i2c_nuvoton_get_burstcount(client,
384 								 chip);
385 			if (burst_count < 0) {
386 				dev_err(dev, "%s() fail get burstCount\n",
387 					__func__);
388 				rc = -EIO;
389 				break;
390 			}
391 			bytes2write = min_t(size_t, burst_count,
392 					    len - 1 - count);
393 			rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W,
394 						   bytes2write, &buf[count]);
395 			if (rc < 0) {
396 				dev_err(dev, "%s() fail i2cWriteBuf\n",
397 					__func__);
398 				break;
399 			}
400 			dev_dbg(dev, "%s(%d):", __func__, bytes2write);
401 			count += bytes2write;
402 			rc = i2c_nuvoton_wait_for_stat(chip,
403 						       TPM_STS_VALID |
404 						       TPM_STS_EXPECT,
405 						       TPM_STS_VALID |
406 						       TPM_STS_EXPECT,
407 						       chip->timeout_c,
408 						       NULL);
409 			if (rc < 0) {
410 				dev_err(dev, "%s() timeout on Expect\n",
411 					__func__);
412 				rc = -ETIMEDOUT;
413 				break;
414 			}
415 		}
416 		if (rc < 0)
417 			continue;
418 
419 		/* write last byte */
420 		rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W, 1,
421 					   &buf[count]);
422 		if (rc < 0) {
423 			dev_err(dev, "%s() fail to write last byte\n",
424 				__func__);
425 			rc = -EIO;
426 			continue;
427 		}
428 		dev_dbg(dev, "%s(last): %02x", __func__, buf[count]);
429 		rc = i2c_nuvoton_wait_for_stat(chip,
430 					       TPM_STS_VALID | TPM_STS_EXPECT,
431 					       TPM_STS_VALID,
432 					       chip->timeout_c, NULL);
433 		if (rc) {
434 			dev_err(dev, "%s() timeout on Expect to clear\n",
435 				__func__);
436 			rc = -ETIMEDOUT;
437 			continue;
438 		}
439 		break;
440 	}
441 	if (rc < 0) {
442 		/* retries == TPM_RETRY */
443 		i2c_nuvoton_ready(chip);
444 		return rc;
445 	}
446 	/* execute the TPM command */
447 	rc = i2c_nuvoton_write_status(client, TPM_STS_GO);
448 	if (rc < 0) {
449 		dev_err(dev, "%s() fail to write Go\n", __func__);
450 		i2c_nuvoton_ready(chip);
451 		return rc;
452 	}
453 	ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
454 	rc = i2c_nuvoton_wait_for_data_avail(chip,
455 					     tpm_calc_ordinal_duration(chip,
456 								       ordinal),
457 					     &priv->read_queue);
458 	if (rc) {
459 		dev_err(dev, "%s() timeout command duration\n", __func__);
460 		i2c_nuvoton_ready(chip);
461 		return rc;
462 	}
463 
464 	dev_dbg(dev, "%s() -> %zd\n", __func__, len);
465 	return len;
466 }
467 
468 static bool i2c_nuvoton_req_canceled(struct tpm_chip *chip, u8 status)
469 {
470 	return (status == TPM_STS_COMMAND_READY);
471 }
472 
473 static const struct tpm_class_ops tpm_i2c = {
474 	.flags = TPM_OPS_AUTO_STARTUP,
475 	.status = i2c_nuvoton_read_status,
476 	.recv = i2c_nuvoton_recv,
477 	.send = i2c_nuvoton_send,
478 	.cancel = i2c_nuvoton_ready,
479 	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
480 	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
481 	.req_canceled = i2c_nuvoton_req_canceled,
482 };
483 
484 /* The only purpose for the handler is to signal to any waiting threads that
485  * the interrupt is currently being asserted. The driver does not do any
486  * processing triggered by interrupts, and the chip provides no way to mask at
487  * the source (plus that would be slow over I2C). Run the IRQ as a one-shot,
488  * this means it cannot be shared. */
489 static irqreturn_t i2c_nuvoton_int_handler(int dummy, void *dev_id)
490 {
491 	struct tpm_chip *chip = dev_id;
492 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
493 
494 	priv->intrs++;
495 	wake_up(&priv->read_queue);
496 	disable_irq_nosync(priv->irq);
497 	return IRQ_HANDLED;
498 }
499 
500 static int get_vid(struct i2c_client *client, u32 *res)
501 {
502 	static const u8 vid_did_rid_value[] = { 0x50, 0x10, 0xfe };
503 	u32 temp;
504 	s32 rc;
505 
506 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
507 		return -ENODEV;
508 	rc = i2c_nuvoton_read_buf(client, TPM_VID_DID_RID, 4, (u8 *)&temp);
509 	if (rc < 0)
510 		return rc;
511 
512 	/* check WPCT301 values - ignore RID */
513 	if (memcmp(&temp, vid_did_rid_value, sizeof(vid_did_rid_value))) {
514 		/*
515 		 * f/w rev 2.81 has an issue where the VID_DID_RID is not
516 		 * reporting the right value. so give it another chance at
517 		 * offset 0x20 (FIFO_W).
518 		 */
519 		rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_W, 4,
520 					  (u8 *) (&temp));
521 		if (rc < 0)
522 			return rc;
523 
524 		/* check WPCT301 values - ignore RID */
525 		if (memcmp(&temp, vid_did_rid_value,
526 			   sizeof(vid_did_rid_value)))
527 			return -ENODEV;
528 	}
529 
530 	*res = temp;
531 	return 0;
532 }
533 
534 static int i2c_nuvoton_probe(struct i2c_client *client,
535 			     const struct i2c_device_id *id)
536 {
537 	int rc;
538 	struct tpm_chip *chip;
539 	struct device *dev = &client->dev;
540 	struct priv_data *priv;
541 	u32 vid = 0;
542 
543 	rc = get_vid(client, &vid);
544 	if (rc)
545 		return rc;
546 
547 	dev_info(dev, "VID: %04X DID: %02X RID: %02X\n", (u16) vid,
548 		 (u8) (vid >> 16), (u8) (vid >> 24));
549 
550 	chip = tpmm_chip_alloc(dev, &tpm_i2c);
551 	if (IS_ERR(chip))
552 		return PTR_ERR(chip);
553 
554 	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
555 	if (!priv)
556 		return -ENOMEM;
557 
558 	if (dev->of_node) {
559 		const struct of_device_id *of_id;
560 
561 		of_id = of_match_device(dev->driver->of_match_table, dev);
562 		if (of_id && of_id->data == OF_IS_TPM2)
563 			chip->flags |= TPM_CHIP_FLAG_TPM2;
564 	} else
565 		if (id->driver_data == I2C_IS_TPM2)
566 			chip->flags |= TPM_CHIP_FLAG_TPM2;
567 
568 	init_waitqueue_head(&priv->read_queue);
569 
570 	/* Default timeouts */
571 	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
572 	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
573 	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
574 	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
575 
576 	dev_set_drvdata(&chip->dev, priv);
577 
578 	/*
579 	 * I2C intfcaps (interrupt capabilitieis) in the chip are hard coded to:
580 	 *   TPM_INTF_INT_LEVEL_LOW | TPM_INTF_DATA_AVAIL_INT
581 	 * The IRQ should be set in the i2c_board_info (which is done
582 	 * automatically in of_i2c_register_devices, for device tree users */
583 	priv->irq = client->irq;
584 	if (client->irq) {
585 		dev_dbg(dev, "%s() priv->irq\n", __func__);
586 		rc = devm_request_irq(dev, client->irq,
587 				      i2c_nuvoton_int_handler,
588 				      IRQF_TRIGGER_LOW,
589 				      dev_name(&chip->dev),
590 				      chip);
591 		if (rc) {
592 			dev_err(dev, "%s() Unable to request irq: %d for use\n",
593 				__func__, priv->irq);
594 			priv->irq = 0;
595 		} else {
596 			chip->flags |= TPM_CHIP_FLAG_IRQ;
597 			/* Clear any pending interrupt */
598 			i2c_nuvoton_ready(chip);
599 			/* - wait for TPM_STS==0xA0 (stsValid, commandReady) */
600 			rc = i2c_nuvoton_wait_for_stat(chip,
601 						       TPM_STS_COMMAND_READY,
602 						       TPM_STS_COMMAND_READY,
603 						       chip->timeout_b,
604 						       NULL);
605 			if (rc == 0) {
606 				/*
607 				 * TIS is in ready state
608 				 * write dummy byte to enter reception state
609 				 * TPM_DATA_FIFO_W <- rc (0)
610 				 */
611 				rc = i2c_nuvoton_write_buf(client,
612 							   TPM_DATA_FIFO_W,
613 							   1, (u8 *) (&rc));
614 				if (rc < 0)
615 					return rc;
616 				/* TPM_STS <- 0x40 (commandReady) */
617 				i2c_nuvoton_ready(chip);
618 			} else {
619 				/*
620 				 * timeout_b reached - command was
621 				 * aborted. TIS should now be in idle state -
622 				 * only TPM_STS_VALID should be set
623 				 */
624 				if (i2c_nuvoton_read_status(chip) !=
625 				    TPM_STS_VALID)
626 					return -EIO;
627 			}
628 		}
629 	}
630 
631 	return tpm_chip_register(chip);
632 }
633 
634 static int i2c_nuvoton_remove(struct i2c_client *client)
635 {
636 	struct tpm_chip *chip = i2c_get_clientdata(client);
637 
638 	tpm_chip_unregister(chip);
639 	return 0;
640 }
641 
642 static const struct i2c_device_id i2c_nuvoton_id[] = {
643 	{"tpm_i2c_nuvoton"},
644 	{"tpm2_i2c_nuvoton", .driver_data = I2C_IS_TPM2},
645 	{}
646 };
647 MODULE_DEVICE_TABLE(i2c, i2c_nuvoton_id);
648 
649 #ifdef CONFIG_OF
650 static const struct of_device_id i2c_nuvoton_of_match[] = {
651 	{.compatible = "nuvoton,npct501"},
652 	{.compatible = "winbond,wpct301"},
653 	{.compatible = "nuvoton,npct601", .data = OF_IS_TPM2},
654 	{},
655 };
656 MODULE_DEVICE_TABLE(of, i2c_nuvoton_of_match);
657 #endif
658 
659 static SIMPLE_DEV_PM_OPS(i2c_nuvoton_pm_ops, tpm_pm_suspend, tpm_pm_resume);
660 
661 static struct i2c_driver i2c_nuvoton_driver = {
662 	.id_table = i2c_nuvoton_id,
663 	.probe = i2c_nuvoton_probe,
664 	.remove = i2c_nuvoton_remove,
665 	.driver = {
666 		.name = "tpm_i2c_nuvoton",
667 		.pm = &i2c_nuvoton_pm_ops,
668 		.of_match_table = of_match_ptr(i2c_nuvoton_of_match),
669 	},
670 };
671 
672 module_i2c_driver(i2c_nuvoton_driver);
673 
674 MODULE_AUTHOR("Dan Morav (dan.morav@nuvoton.com)");
675 MODULE_DESCRIPTION("Nuvoton TPM I2C Driver");
676 MODULE_LICENSE("GPL");
677