1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2020 Google Inc.
4  *
5  * Based on Infineon TPM driver by Peter Huewe.
6  *
7  * cr50 is a firmware for H1 secure modules that requires special
8  * handling for the I2C interface.
9  *
10  * - Use an interrupt for transaction status instead of hardcoded delays.
11  * - Must use write+wait+read read protocol.
12  * - All 4 bytes of status register must be read/written at once.
13  * - Burst count max is 63 bytes, and burst count behaves slightly differently
14  *   than other I2C TPMs.
15  * - When reading from FIFO the full burstcnt must be read instead of just
16  *   reading header and determining the remainder.
17  */
18 
19 #include <linux/acpi.h>
20 #include <linux/completion.h>
21 #include <linux/i2c.h>
22 #include <linux/interrupt.h>
23 #include <linux/module.h>
24 #include <linux/pm.h>
25 #include <linux/slab.h>
26 #include <linux/wait.h>
27 
28 #include "tpm_tis_core.h"
29 
30 #define TPM_CR50_MAX_BUFSIZE		64
31 #define TPM_CR50_TIMEOUT_SHORT_MS	2		/* Short timeout during transactions */
32 #define TPM_CR50_TIMEOUT_NOIRQ_MS	20		/* Timeout for TPM ready without IRQ */
33 #define TPM_CR50_I2C_DID_VID		0x00281ae0L	/* Device and vendor ID reg value */
34 #define TPM_TI50_I2C_DID_VID		0x504a6666L	/* Device and vendor ID reg value */
35 #define TPM_CR50_I2C_MAX_RETRIES	3		/* Max retries due to I2C errors */
36 #define TPM_CR50_I2C_RETRY_DELAY_LO	55		/* Min usecs between retries on I2C */
37 #define TPM_CR50_I2C_RETRY_DELAY_HI	65		/* Max usecs between retries on I2C */
38 
39 #define TPM_I2C_ACCESS(l)	(0x0000 | ((l) << 4))
40 #define TPM_I2C_STS(l)		(0x0001 | ((l) << 4))
41 #define TPM_I2C_DATA_FIFO(l)	(0x0005 | ((l) << 4))
42 #define TPM_I2C_DID_VID(l)	(0x0006 | ((l) << 4))
43 
44 /**
45  * struct tpm_i2c_cr50_priv_data - Driver private data.
46  * @irq:	Irq number used for this chip.
47  *		If irq <= 0, then a fixed timeout is used instead of waiting for irq.
48  * @tpm_ready:	Struct used by irq handler to signal R/W readiness.
49  * @buf:	Buffer used for i2c writes, with i2c address prepended to content.
50  *
51  * Private driver struct used by kernel threads and interrupt context.
52  */
53 struct tpm_i2c_cr50_priv_data {
54 	int irq;
55 	struct completion tpm_ready;
56 	u8 buf[TPM_CR50_MAX_BUFSIZE];
57 };
58 
59 /**
60  * tpm_cr50_i2c_int_handler() - cr50 interrupt handler.
61  * @dummy:	Unused parameter.
62  * @tpm_info:	TPM chip information.
63  *
64  * The cr50 interrupt handler signals waiting threads that the
65  * interrupt has been asserted. It does not do any interrupt triggered
66  * processing but is instead used to avoid fixed delays.
67  *
68  * Return:
69  *	IRQ_HANDLED signifies irq was handled by this device.
70  */
71 static irqreturn_t tpm_cr50_i2c_int_handler(int dummy, void *tpm_info)
72 {
73 	struct tpm_chip *chip = tpm_info;
74 	struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev);
75 
76 	complete(&priv->tpm_ready);
77 
78 	return IRQ_HANDLED;
79 }
80 
81 /**
82  * tpm_cr50_i2c_wait_tpm_ready() - Wait for tpm to signal ready.
83  * @chip: A TPM chip.
84  *
85  * Wait for completion interrupt if available, otherwise use a fixed
86  * delay for the TPM to be ready.
87  *
88  * Return:
89  * - 0:		Success.
90  * - -errno:	A POSIX error code.
91  */
92 static int tpm_cr50_i2c_wait_tpm_ready(struct tpm_chip *chip)
93 {
94 	struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev);
95 
96 	/* Use a safe fixed delay if interrupt is not supported */
97 	if (priv->irq <= 0) {
98 		msleep(TPM_CR50_TIMEOUT_NOIRQ_MS);
99 		return 0;
100 	}
101 
102 	/* Wait for interrupt to indicate TPM is ready to respond */
103 	if (!wait_for_completion_timeout(&priv->tpm_ready,
104 					 msecs_to_jiffies(chip->timeout_a))) {
105 		dev_warn(&chip->dev, "Timeout waiting for TPM ready\n");
106 		return -ETIMEDOUT;
107 	}
108 
109 	return 0;
110 }
111 
112 /**
113  * tpm_cr50_i2c_enable_tpm_irq() - Enable TPM irq.
114  * @chip: A TPM chip.
115  */
116 static void tpm_cr50_i2c_enable_tpm_irq(struct tpm_chip *chip)
117 {
118 	struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev);
119 
120 	if (priv->irq > 0) {
121 		reinit_completion(&priv->tpm_ready);
122 		enable_irq(priv->irq);
123 	}
124 }
125 
126 /**
127  * tpm_cr50_i2c_disable_tpm_irq() - Disable TPM irq.
128  * @chip: A TPM chip.
129  */
130 static void tpm_cr50_i2c_disable_tpm_irq(struct tpm_chip *chip)
131 {
132 	struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev);
133 
134 	if (priv->irq > 0)
135 		disable_irq(priv->irq);
136 }
137 
138 /**
139  * tpm_cr50_i2c_transfer_message() - Transfer a message over i2c.
140  * @dev:	Device information.
141  * @adapter:	I2C adapter.
142  * @msg:	Message to transfer.
143  *
144  * Call unlocked i2c transfer routine with the provided parameters and
145  * retry in case of bus errors.
146  *
147  * Return:
148  * - 0:		Success.
149  * - -errno:	A POSIX error code.
150  */
151 static int tpm_cr50_i2c_transfer_message(struct device *dev,
152 					 struct i2c_adapter *adapter,
153 					 struct i2c_msg *msg)
154 {
155 	unsigned int try;
156 	int rc;
157 
158 	for (try = 0; try < TPM_CR50_I2C_MAX_RETRIES; try++) {
159 		rc = __i2c_transfer(adapter, msg, 1);
160 		if (rc == 1)
161 			return 0; /* Successfully transferred the message */
162 		if (try)
163 			dev_warn(dev, "i2c transfer failed (attempt %d/%d): %d\n",
164 				 try + 1, TPM_CR50_I2C_MAX_RETRIES, rc);
165 		usleep_range(TPM_CR50_I2C_RETRY_DELAY_LO, TPM_CR50_I2C_RETRY_DELAY_HI);
166 	}
167 
168 	/* No i2c message transferred */
169 	return -EIO;
170 }
171 
172 /**
173  * tpm_cr50_i2c_read() - Read from TPM register.
174  * @chip:	A TPM chip.
175  * @addr:	Register address to read from.
176  * @buffer:	Read destination, provided by caller.
177  * @len:	Number of bytes to read.
178  *
179  * Sends the register address byte to the TPM, then waits until TPM
180  * is ready via interrupt signal or timeout expiration, then 'len'
181  * bytes are read from TPM response into the provided 'buffer'.
182  *
183  * Return:
184  * - 0:		Success.
185  * - -errno:	A POSIX error code.
186  */
187 static int tpm_cr50_i2c_read(struct tpm_chip *chip, u8 addr, u8 *buffer, size_t len)
188 {
189 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
190 	struct i2c_msg msg_reg_addr = {
191 		.addr = client->addr,
192 		.len = 1,
193 		.buf = &addr
194 	};
195 	struct i2c_msg msg_response = {
196 		.addr = client->addr,
197 		.flags = I2C_M_RD,
198 		.len = len,
199 		.buf = buffer
200 	};
201 	int rc;
202 
203 	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
204 
205 	/* Prepare for completion interrupt */
206 	tpm_cr50_i2c_enable_tpm_irq(chip);
207 
208 	/* Send the register address byte to the TPM */
209 	rc = tpm_cr50_i2c_transfer_message(&chip->dev, client->adapter, &msg_reg_addr);
210 	if (rc < 0)
211 		goto out;
212 
213 	/* Wait for TPM to be ready with response data */
214 	rc = tpm_cr50_i2c_wait_tpm_ready(chip);
215 	if (rc < 0)
216 		goto out;
217 
218 	/* Read response data from the TPM */
219 	rc = tpm_cr50_i2c_transfer_message(&chip->dev, client->adapter, &msg_response);
220 
221 out:
222 	tpm_cr50_i2c_disable_tpm_irq(chip);
223 	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
224 
225 	if (rc < 0)
226 		return rc;
227 
228 	return 0;
229 }
230 
231 /**
232  * tpm_cr50_i2c_write()- Write to TPM register.
233  * @chip:	A TPM chip.
234  * @addr:	Register address to write to.
235  * @buffer:	Data to write.
236  * @len:	Number of bytes to write.
237  *
238  * The provided address is prepended to the data in 'buffer', the
239  * cobined address+data is sent to the TPM, then wait for TPM to
240  * indicate it is done writing.
241  *
242  * Return:
243  * - 0:		Success.
244  * - -errno:	A POSIX error code.
245  */
246 static int tpm_cr50_i2c_write(struct tpm_chip *chip, u8 addr, u8 *buffer,
247 			      size_t len)
248 {
249 	struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev);
250 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
251 	struct i2c_msg msg = {
252 		.addr = client->addr,
253 		.len = len + 1,
254 		.buf = priv->buf
255 	};
256 	int rc;
257 
258 	if (len > TPM_CR50_MAX_BUFSIZE - 1)
259 		return -EINVAL;
260 
261 	/* Prepend the 'register address' to the buffer */
262 	priv->buf[0] = addr;
263 	memcpy(priv->buf + 1, buffer, len);
264 
265 	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
266 
267 	/* Prepare for completion interrupt */
268 	tpm_cr50_i2c_enable_tpm_irq(chip);
269 
270 	/* Send write request buffer with address */
271 	rc = tpm_cr50_i2c_transfer_message(&chip->dev, client->adapter, &msg);
272 	if (rc < 0)
273 		goto out;
274 
275 	/* Wait for TPM to be ready, ignore timeout */
276 	tpm_cr50_i2c_wait_tpm_ready(chip);
277 
278 out:
279 	tpm_cr50_i2c_disable_tpm_irq(chip);
280 	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
281 
282 	if (rc < 0)
283 		return rc;
284 
285 	return 0;
286 }
287 
288 /**
289  * tpm_cr50_check_locality() - Verify TPM locality 0 is active.
290  * @chip: A TPM chip.
291  *
292  * Return:
293  * - 0:		Success.
294  * - -errno:	A POSIX error code.
295  */
296 static int tpm_cr50_check_locality(struct tpm_chip *chip)
297 {
298 	u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
299 	u8 buf;
300 	int rc;
301 
302 	rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
303 	if (rc < 0)
304 		return rc;
305 
306 	if ((buf & mask) == mask)
307 		return 0;
308 
309 	return -EIO;
310 }
311 
312 /**
313  * tpm_cr50_release_locality() - Release TPM locality.
314  * @chip:	A TPM chip.
315  * @force:	Flag to force release if set.
316  */
317 static void tpm_cr50_release_locality(struct tpm_chip *chip, bool force)
318 {
319 	u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_PENDING;
320 	u8 addr = TPM_I2C_ACCESS(0);
321 	u8 buf;
322 
323 	if (tpm_cr50_i2c_read(chip, addr, &buf, sizeof(buf)) < 0)
324 		return;
325 
326 	if (force || (buf & mask) == mask) {
327 		buf = TPM_ACCESS_ACTIVE_LOCALITY;
328 		tpm_cr50_i2c_write(chip, addr, &buf, sizeof(buf));
329 	}
330 }
331 
332 /**
333  * tpm_cr50_request_locality() - Request TPM locality 0.
334  * @chip: A TPM chip.
335  *
336  * Return:
337  * - 0:		Success.
338  * - -errno:	A POSIX error code.
339  */
340 static int tpm_cr50_request_locality(struct tpm_chip *chip)
341 {
342 	u8 buf = TPM_ACCESS_REQUEST_USE;
343 	unsigned long stop;
344 	int rc;
345 
346 	if (!tpm_cr50_check_locality(chip))
347 		return 0;
348 
349 	rc = tpm_cr50_i2c_write(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
350 	if (rc < 0)
351 		return rc;
352 
353 	stop = jiffies + chip->timeout_a;
354 	do {
355 		if (!tpm_cr50_check_locality(chip))
356 			return 0;
357 
358 		msleep(TPM_CR50_TIMEOUT_SHORT_MS);
359 	} while (time_before(jiffies, stop));
360 
361 	return -ETIMEDOUT;
362 }
363 
364 /**
365  * tpm_cr50_i2c_tis_status() - Read cr50 tis status.
366  * @chip: A TPM chip.
367  *
368  * cr50 requires all 4 bytes of status register to be read.
369  *
370  * Return:
371  *	TPM status byte.
372  */
373 static u8 tpm_cr50_i2c_tis_status(struct tpm_chip *chip)
374 {
375 	u8 buf[4];
376 
377 	if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0)
378 		return 0;
379 
380 	return buf[0];
381 }
382 
383 /**
384  * tpm_cr50_i2c_tis_set_ready() - Set status register to ready.
385  * @chip: A TPM chip.
386  *
387  * cr50 requires all 4 bytes of status register to be written.
388  */
389 static void tpm_cr50_i2c_tis_set_ready(struct tpm_chip *chip)
390 {
391 	u8 buf[4] = { TPM_STS_COMMAND_READY };
392 
393 	tpm_cr50_i2c_write(chip, TPM_I2C_STS(0), buf, sizeof(buf));
394 	msleep(TPM_CR50_TIMEOUT_SHORT_MS);
395 }
396 
397 /**
398  * tpm_cr50_i2c_get_burst_and_status() - Get burst count and status.
399  * @chip:	A TPM chip.
400  * @mask:	Status mask.
401  * @burst:	Return value for burst.
402  * @status:	Return value for status.
403  *
404  * cr50 uses bytes 3:2 of status register for burst count and
405  * all 4 bytes must be read.
406  *
407  * Return:
408  * - 0:		Success.
409  * - -errno:	A POSIX error code.
410  */
411 static int tpm_cr50_i2c_get_burst_and_status(struct tpm_chip *chip, u8 mask,
412 					     size_t *burst, u32 *status)
413 {
414 	unsigned long stop;
415 	u8 buf[4];
416 
417 	*status = 0;
418 
419 	/* wait for burstcount */
420 	stop = jiffies + chip->timeout_b;
421 
422 	do {
423 		if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0) {
424 			msleep(TPM_CR50_TIMEOUT_SHORT_MS);
425 			continue;
426 		}
427 
428 		*status = *buf;
429 		*burst = le16_to_cpup((__le16 *)(buf + 1));
430 
431 		if ((*status & mask) == mask &&
432 		    *burst > 0 && *burst <= TPM_CR50_MAX_BUFSIZE - 1)
433 			return 0;
434 
435 		msleep(TPM_CR50_TIMEOUT_SHORT_MS);
436 	} while (time_before(jiffies, stop));
437 
438 	dev_err(&chip->dev, "Timeout reading burst and status\n");
439 	return -ETIMEDOUT;
440 }
441 
442 /**
443  * tpm_cr50_i2c_tis_recv() - TPM reception callback.
444  * @chip:	A TPM chip.
445  * @buf:	Reception buffer.
446  * @buf_len:	Buffer length to read.
447  *
448  * Return:
449  * - >= 0:	Number of read bytes.
450  * - -errno:	A POSIX error code.
451  */
452 static int tpm_cr50_i2c_tis_recv(struct tpm_chip *chip, u8 *buf, size_t buf_len)
453 {
454 
455 	u8 mask = TPM_STS_VALID | TPM_STS_DATA_AVAIL;
456 	size_t burstcnt, cur, len, expected;
457 	u8 addr = TPM_I2C_DATA_FIFO(0);
458 	u32 status;
459 	int rc;
460 
461 	if (buf_len < TPM_HEADER_SIZE)
462 		return -EINVAL;
463 
464 	rc = tpm_cr50_i2c_get_burst_and_status(chip, mask, &burstcnt, &status);
465 	if (rc < 0)
466 		goto out_err;
467 
468 	if (burstcnt > buf_len || burstcnt < TPM_HEADER_SIZE) {
469 		dev_err(&chip->dev,
470 			"Unexpected burstcnt: %zu (max=%zu, min=%d)\n",
471 			burstcnt, buf_len, TPM_HEADER_SIZE);
472 		rc = -EIO;
473 		goto out_err;
474 	}
475 
476 	/* Read first chunk of burstcnt bytes */
477 	rc = tpm_cr50_i2c_read(chip, addr, buf, burstcnt);
478 	if (rc < 0) {
479 		dev_err(&chip->dev, "Read of first chunk failed\n");
480 		goto out_err;
481 	}
482 
483 	/* Determine expected data in the return buffer */
484 	expected = be32_to_cpup((__be32 *)(buf + 2));
485 	if (expected > buf_len) {
486 		dev_err(&chip->dev, "Buffer too small to receive i2c data\n");
487 		rc = -E2BIG;
488 		goto out_err;
489 	}
490 
491 	/* Now read the rest of the data */
492 	cur = burstcnt;
493 	while (cur < expected) {
494 		/* Read updated burst count and check status */
495 		rc = tpm_cr50_i2c_get_burst_and_status(chip, mask, &burstcnt, &status);
496 		if (rc < 0)
497 			goto out_err;
498 
499 		len = min_t(size_t, burstcnt, expected - cur);
500 		rc = tpm_cr50_i2c_read(chip, addr, buf + cur, len);
501 		if (rc < 0) {
502 			dev_err(&chip->dev, "Read failed\n");
503 			goto out_err;
504 		}
505 
506 		cur += len;
507 	}
508 
509 	/* Ensure TPM is done reading data */
510 	rc = tpm_cr50_i2c_get_burst_and_status(chip, TPM_STS_VALID, &burstcnt, &status);
511 	if (rc < 0)
512 		goto out_err;
513 	if (status & TPM_STS_DATA_AVAIL) {
514 		dev_err(&chip->dev, "Data still available\n");
515 		rc = -EIO;
516 		goto out_err;
517 	}
518 
519 	tpm_cr50_release_locality(chip, false);
520 	return cur;
521 
522 out_err:
523 	/* Abort current transaction if still pending */
524 	if (tpm_cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY)
525 		tpm_cr50_i2c_tis_set_ready(chip);
526 
527 	tpm_cr50_release_locality(chip, false);
528 	return rc;
529 }
530 
531 /**
532  * tpm_cr50_i2c_tis_send() - TPM transmission callback.
533  * @chip:	A TPM chip.
534  * @buf:	Buffer to send.
535  * @len:	Buffer length.
536  *
537  * Return:
538  * - 0:		Success.
539  * - -errno:	A POSIX error code.
540  */
541 static int tpm_cr50_i2c_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
542 {
543 	size_t burstcnt, limit, sent = 0;
544 	u8 tpm_go[4] = { TPM_STS_GO };
545 	unsigned long stop;
546 	u32 status;
547 	int rc;
548 
549 	rc = tpm_cr50_request_locality(chip);
550 	if (rc < 0)
551 		return rc;
552 
553 	/* Wait until TPM is ready for a command */
554 	stop = jiffies + chip->timeout_b;
555 	while (!(tpm_cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY)) {
556 		if (time_after(jiffies, stop)) {
557 			rc = -ETIMEDOUT;
558 			goto out_err;
559 		}
560 
561 		tpm_cr50_i2c_tis_set_ready(chip);
562 	}
563 
564 	while (len > 0) {
565 		u8 mask = TPM_STS_VALID;
566 
567 		/* Wait for data if this is not the first chunk */
568 		if (sent > 0)
569 			mask |= TPM_STS_DATA_EXPECT;
570 
571 		/* Read burst count and check status */
572 		rc = tpm_cr50_i2c_get_burst_and_status(chip, mask, &burstcnt, &status);
573 		if (rc < 0)
574 			goto out_err;
575 
576 		/*
577 		 * Use burstcnt - 1 to account for the address byte
578 		 * that is inserted by tpm_cr50_i2c_write()
579 		 */
580 		limit = min_t(size_t, burstcnt - 1, len);
581 		rc = tpm_cr50_i2c_write(chip, TPM_I2C_DATA_FIFO(0), &buf[sent], limit);
582 		if (rc < 0) {
583 			dev_err(&chip->dev, "Write failed\n");
584 			goto out_err;
585 		}
586 
587 		sent += limit;
588 		len -= limit;
589 	}
590 
591 	/* Ensure TPM is not expecting more data */
592 	rc = tpm_cr50_i2c_get_burst_and_status(chip, TPM_STS_VALID, &burstcnt, &status);
593 	if (rc < 0)
594 		goto out_err;
595 	if (status & TPM_STS_DATA_EXPECT) {
596 		dev_err(&chip->dev, "Data still expected\n");
597 		rc = -EIO;
598 		goto out_err;
599 	}
600 
601 	/* Start the TPM command */
602 	rc = tpm_cr50_i2c_write(chip, TPM_I2C_STS(0), tpm_go,
603 				sizeof(tpm_go));
604 	if (rc < 0) {
605 		dev_err(&chip->dev, "Start command failed\n");
606 		goto out_err;
607 	}
608 	return 0;
609 
610 out_err:
611 	/* Abort current transaction if still pending */
612 	if (tpm_cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY)
613 		tpm_cr50_i2c_tis_set_ready(chip);
614 
615 	tpm_cr50_release_locality(chip, false);
616 	return rc;
617 }
618 
619 /**
620  * tpm_cr50_i2c_req_canceled() - Callback to notify a request cancel.
621  * @chip:	A TPM chip.
622  * @status:	Status given by the cancel callback.
623  *
624  * Return:
625  *	True if command is ready, False otherwise.
626  */
627 static bool tpm_cr50_i2c_req_canceled(struct tpm_chip *chip, u8 status)
628 {
629 	return status == TPM_STS_COMMAND_READY;
630 }
631 
632 static bool tpm_cr50_i2c_is_firmware_power_managed(struct device *dev)
633 {
634 	u8 val;
635 	int ret;
636 
637 	/* This flag should default true when the device property is not present */
638 	ret = device_property_read_u8(dev, "firmware-power-managed", &val);
639 	if (ret)
640 		return true;
641 
642 	return val;
643 }
644 
645 static const struct tpm_class_ops cr50_i2c = {
646 	.flags = TPM_OPS_AUTO_STARTUP,
647 	.status = &tpm_cr50_i2c_tis_status,
648 	.recv = &tpm_cr50_i2c_tis_recv,
649 	.send = &tpm_cr50_i2c_tis_send,
650 	.cancel = &tpm_cr50_i2c_tis_set_ready,
651 	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
652 	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
653 	.req_canceled = &tpm_cr50_i2c_req_canceled,
654 };
655 
656 #ifdef CONFIG_ACPI
657 static const struct acpi_device_id cr50_i2c_acpi_id[] = {
658 	{ "GOOG0005", 0 },
659 	{}
660 };
661 MODULE_DEVICE_TABLE(acpi, cr50_i2c_acpi_id);
662 #endif
663 
664 #ifdef CONFIG_OF
665 static const struct of_device_id of_cr50_i2c_match[] = {
666 	{ .compatible = "google,cr50", },
667 	{}
668 };
669 MODULE_DEVICE_TABLE(of, of_cr50_i2c_match);
670 #endif
671 
672 /**
673  * tpm_cr50_i2c_probe() - Driver probe function.
674  * @client:	I2C client information.
675  * @id:		I2C device id.
676  *
677  * Return:
678  * - 0:		Success.
679  * - -errno:	A POSIX error code.
680  */
681 static int tpm_cr50_i2c_probe(struct i2c_client *client)
682 {
683 	struct tpm_i2c_cr50_priv_data *priv;
684 	struct device *dev = &client->dev;
685 	struct tpm_chip *chip;
686 	u32 vendor;
687 	u8 buf[4];
688 	int rc;
689 
690 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
691 		return -ENODEV;
692 
693 	chip = tpmm_chip_alloc(dev, &cr50_i2c);
694 	if (IS_ERR(chip))
695 		return PTR_ERR(chip);
696 
697 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
698 	if (!priv)
699 		return -ENOMEM;
700 
701 	/* cr50 is a TPM 2.0 chip */
702 	chip->flags |= TPM_CHIP_FLAG_TPM2;
703 	if (tpm_cr50_i2c_is_firmware_power_managed(dev))
704 		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED;
705 
706 	/* Default timeouts */
707 	chip->timeout_a = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
708 	chip->timeout_b = msecs_to_jiffies(TIS_LONG_TIMEOUT);
709 	chip->timeout_c = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
710 	chip->timeout_d = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
711 
712 	dev_set_drvdata(&chip->dev, priv);
713 	init_completion(&priv->tpm_ready);
714 
715 	if (client->irq > 0) {
716 		rc = devm_request_irq(dev, client->irq, tpm_cr50_i2c_int_handler,
717 				      IRQF_TRIGGER_FALLING | IRQF_ONESHOT |
718 				      IRQF_NO_AUTOEN,
719 				      dev->driver->name, chip);
720 		if (rc < 0) {
721 			dev_err(dev, "Failed to probe IRQ %d\n", client->irq);
722 			return rc;
723 		}
724 
725 		priv->irq = client->irq;
726 	} else {
727 		dev_warn(dev, "No IRQ, will use %ums delay for TPM ready\n",
728 			 TPM_CR50_TIMEOUT_NOIRQ_MS);
729 	}
730 
731 	rc = tpm_cr50_request_locality(chip);
732 	if (rc < 0) {
733 		dev_err(dev, "Could not request locality\n");
734 		return rc;
735 	}
736 
737 	/* Read four bytes from DID_VID register */
738 	rc = tpm_cr50_i2c_read(chip, TPM_I2C_DID_VID(0), buf, sizeof(buf));
739 	if (rc < 0) {
740 		dev_err(dev, "Could not read vendor id\n");
741 		tpm_cr50_release_locality(chip, true);
742 		return rc;
743 	}
744 
745 	vendor = le32_to_cpup((__le32 *)buf);
746 	if (vendor != TPM_CR50_I2C_DID_VID && vendor != TPM_TI50_I2C_DID_VID) {
747 		dev_err(dev, "Vendor ID did not match! ID was %08x\n", vendor);
748 		tpm_cr50_release_locality(chip, true);
749 		return -ENODEV;
750 	}
751 
752 	dev_info(dev, "%s TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
753 		 vendor == TPM_TI50_I2C_DID_VID ? "ti50" : "cr50",
754 		 client->addr, client->irq, vendor >> 16);
755 	return tpm_chip_register(chip);
756 }
757 
758 /**
759  * tpm_cr50_i2c_remove() - Driver remove function.
760  * @client: I2C client information.
761  *
762  * Return:
763  * - 0:		Success.
764  * - -errno:	A POSIX error code.
765  */
766 static int tpm_cr50_i2c_remove(struct i2c_client *client)
767 {
768 	struct tpm_chip *chip = i2c_get_clientdata(client);
769 	struct device *dev = &client->dev;
770 
771 	if (!chip) {
772 		dev_crit(dev, "Could not get client data at remove, memory corruption ahead\n");
773 		return 0;
774 	}
775 
776 	tpm_chip_unregister(chip);
777 	tpm_cr50_release_locality(chip, true);
778 
779 	return 0;
780 }
781 
782 static SIMPLE_DEV_PM_OPS(cr50_i2c_pm, tpm_pm_suspend, tpm_pm_resume);
783 
784 static struct i2c_driver cr50_i2c_driver = {
785 	.probe_new = tpm_cr50_i2c_probe,
786 	.remove = tpm_cr50_i2c_remove,
787 	.driver = {
788 		.name = "cr50_i2c",
789 		.pm = &cr50_i2c_pm,
790 		.acpi_match_table = ACPI_PTR(cr50_i2c_acpi_id),
791 		.of_match_table = of_match_ptr(of_cr50_i2c_match),
792 	},
793 };
794 
795 module_i2c_driver(cr50_i2c_driver);
796 
797 MODULE_DESCRIPTION("cr50 TPM I2C Driver");
798 MODULE_LICENSE("GPL");
799