1 /*
2  * Copyright (C) 2011 Infineon Technologies
3  *
4  * Authors:
5  * Peter Huewe <huewe.external@infineon.com>
6  *
7  * Description:
8  * Device driver for TCG/TCPA TPM (trusted platform module).
9  * Specifications at www.trustedcomputinggroup.org
10  *
11  * This device driver implements the TPM interface as defined in
12  * the TCG TPM Interface Spec version 1.2, revision 1.0 and the
13  * Infineon I2C Protocol Stack Specification v0.20.
14  *
15  * It is based on the Linux kernel driver tpm.c from Leendert van
16  * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
17  *
18  * Version: 2.1.1
19  *
20  * SPDX-License-Identifier:	GPL-2.0
21  */
22 
23 #include <common.h>
24 #include <dm.h>
25 #include <fdtdec.h>
26 #include <i2c.h>
27 #include <tpm.h>
28 #include <linux/errno.h>
29 #include <linux/compiler.h>
30 #include <linux/types.h>
31 #include <linux/unaligned/be_byteshift.h>
32 
33 #include "tpm_tis.h"
34 #include "tpm_internal.h"
35 
36 DECLARE_GLOBAL_DATA_PTR;
37 
38 enum i2c_chip_type {
39 	SLB9635,
40 	SLB9645,
41 	UNKNOWN,
42 };
43 
44 /* expected value for DIDVID register */
45 #define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
46 #define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L
47 
48 static const char * const chip_name[] = {
49 	[SLB9635] = "slb9635tt",
50 	[SLB9645] = "slb9645tt",
51 	[UNKNOWN] = "unknown/fallback to slb9635",
52 };
53 
54 #define	TPM_ACCESS(l)			(0x0000 | ((l) << 4))
55 #define	TPM_STS(l)			(0x0001 | ((l) << 4))
56 #define	TPM_DATA_FIFO(l)		(0x0005 | ((l) << 4))
57 #define	TPM_DID_VID(l)			(0x0006 | ((l) << 4))
58 
59 /*
60  * tpm_tis_i2c_read() - read from TPM register
61  * @addr: register address to read from
62  * @buffer: provided by caller
63  * @len: number of bytes to read
64  *
65  * Read len bytes from TPM register and put them into
66  * buffer (little-endian format, i.e. first byte is put into buffer[0]).
67  *
68  * NOTE: TPM is big-endian for multi-byte values. Multi-byte
69  * values have to be swapped.
70  *
71  * Return -EIO on error, 0 on success.
72  */
73 static int tpm_tis_i2c_read(struct udevice *dev, u8 addr, u8 *buffer,
74 			    size_t len)
75 {
76 	struct tpm_chip *chip = dev_get_priv(dev);
77 	int rc;
78 	int count;
79 	uint32_t addrbuf = addr;
80 
81 	if ((chip->chip_type == SLB9635) || (chip->chip_type == UNKNOWN)) {
82 		/* slb9635 protocol should work in both cases */
83 		for (count = 0; count < MAX_COUNT; count++) {
84 			rc = dm_i2c_write(dev, 0, (uchar *)&addrbuf, 1);
85 			if (rc == 0)
86 				break;  /* Success, break to skip sleep */
87 			udelay(SLEEP_DURATION_US);
88 		}
89 		if (rc)
90 			return rc;
91 
92 		/* After the TPM has successfully received the register address
93 		 * it needs some time, thus we're sleeping here again, before
94 		 * retrieving the data
95 		 */
96 		for (count = 0; count < MAX_COUNT; count++) {
97 			udelay(SLEEP_DURATION_US);
98 			rc = dm_i2c_read(dev, 0, buffer, len);
99 			if (rc == 0)
100 				break;  /* success, break to skip sleep */
101 		}
102 	} else {
103 		/*
104 		 * Use a combined read for newer chips.
105 		 * Unfortunately the smbus functions are not suitable due to
106 		 * the 32 byte limit of the smbus.
107 		 * Retries should usually not be needed, but are kept just to
108 		 * be safe on the safe side.
109 		 */
110 		for (count = 0; count < MAX_COUNT; count++) {
111 			rc = dm_i2c_read(dev, addr, buffer, len);
112 			if (rc == 0)
113 				break;  /* break here to skip sleep */
114 			udelay(SLEEP_DURATION_US);
115 		}
116 	}
117 
118 	/* Take care of 'guard time' */
119 	udelay(SLEEP_DURATION_US);
120 	if (rc)
121 		return rc;
122 
123 	return 0;
124 }
125 
126 static int tpm_tis_i2c_write_generic(struct udevice *dev, u8 addr,
127 				     const u8 *buffer, size_t len,
128 				     unsigned int sleep_time_us, u8 max_count)
129 {
130 	struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
131 	struct tpm_chip *chip = dev_get_priv(dev);
132 	int rc = 0;
133 	int count;
134 
135 	if (chip->chip_type == SLB9635) {
136 		/* Prepare send buffer to include the address */
137 		priv->buf[0] = addr;
138 		memcpy(&(priv->buf[1]), buffer, len);
139 		buffer = priv->buf;
140 		len++;
141 		addr = 0;
142 	}
143 
144 	for (count = 0; count < max_count; count++) {
145 		rc = dm_i2c_write(dev, addr, buffer, len);
146 		if (rc == 0)
147 			break;  /* Success, break to skip sleep */
148 		udelay(sleep_time_us);
149 	}
150 
151 	/* take care of 'guard time' */
152 	udelay(sleep_time_us);
153 	if (rc)
154 		return rc;
155 
156 	return 0;
157 }
158 
159 /*
160  * tpm_tis_i2c_write() - write to TPM register
161  * @addr: register address to write to
162  * @buffer: containing data to be written
163  * @len: number of bytes to write
164  *
165  * Write len bytes from provided buffer to TPM register (little
166  * endian format, i.e. buffer[0] is written as first byte).
167  *
168  * NOTE: TPM is big-endian for multi-byte values. Multi-byte
169  * values have to be swapped.
170  *
171  * NOTE: use this function instead of the tpm_tis_i2c_write_generic function.
172  *
173  * Return -EIO on error, 0 on success
174  */
175 static int tpm_tis_i2c_write(struct udevice *dev, u8 addr, const u8 *buffer,
176 			     size_t len)
177 {
178 	return tpm_tis_i2c_write_generic(dev, addr, buffer, len,
179 					 SLEEP_DURATION_US, MAX_COUNT);
180 }
181 
182 /*
183  * This function is needed especially for the cleanup situation after
184  * sending TPM_READY
185  */
186 static int tpm_tis_i2c_write_long(struct udevice *dev, u8 addr, u8 *buffer,
187 				  size_t len)
188 {
189 	return tpm_tis_i2c_write_generic(dev, addr, buffer, len,
190 					 SLEEP_DURATION_LONG_US,
191 					 MAX_COUNT_LONG);
192 }
193 
194 static int tpm_tis_i2c_check_locality(struct udevice *dev, int loc)
195 {
196 	const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
197 	struct tpm_chip *chip = dev_get_priv(dev);
198 	u8 buf;
199 	int rc;
200 
201 	rc = tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1);
202 	if (rc < 0)
203 		return rc;
204 
205 	if ((buf & mask) == mask) {
206 		chip->locality = loc;
207 		return loc;
208 	}
209 
210 	return -ENOENT;
211 }
212 
213 static void tpm_tis_i2c_release_locality(struct udevice *dev, int loc,
214 					 int force)
215 {
216 	const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
217 	u8 buf;
218 
219 	if (tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1) < 0)
220 		return;
221 
222 	if (force || (buf & mask) == mask) {
223 		buf = TPM_ACCESS_ACTIVE_LOCALITY;
224 		tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);
225 	}
226 }
227 
228 static int tpm_tis_i2c_request_locality(struct udevice *dev, int loc)
229 {
230 	struct tpm_chip *chip = dev_get_priv(dev);
231 	unsigned long start, stop;
232 	u8 buf = TPM_ACCESS_REQUEST_USE;
233 	int rc;
234 
235 	rc = tpm_tis_i2c_check_locality(dev, loc);
236 	if (rc >= 0) {
237 		debug("%s: Already have locality\n", __func__);
238 		return loc;  /* We already have the locality */
239 	} else if (rc != -ENOENT) {
240 		debug("%s: Failed to get locality: %d\n", __func__, rc);
241 		return rc;
242 	}
243 
244 	rc = tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);
245 	if (rc) {
246 		debug("%s: Failed to write to TPM: %d\n", __func__, rc);
247 		return rc;
248 	}
249 
250 	/* Wait for burstcount */
251 	start = get_timer(0);
252 	stop = chip->timeout_a;
253 	do {
254 		rc = tpm_tis_i2c_check_locality(dev, loc);
255 		if (rc >= 0) {
256 			debug("%s: Have locality\n", __func__);
257 			return loc;
258 		} else if (rc != -ENOENT) {
259 			debug("%s: Failed to get locality: %d\n", __func__, rc);
260 			return rc;
261 		}
262 		mdelay(TPM_TIMEOUT_MS);
263 	} while (get_timer(start) < stop);
264 	debug("%s: Timeout getting locality: %d\n", __func__, rc);
265 
266 	return rc;
267 }
268 
269 static u8 tpm_tis_i2c_status(struct udevice *dev)
270 {
271 	struct tpm_chip *chip = dev_get_priv(dev);
272 	/* NOTE: Since i2c read may fail, return 0 in this case --> time-out */
273 	u8 buf;
274 
275 	if (tpm_tis_i2c_read(dev, TPM_STS(chip->locality), &buf, 1) < 0)
276 		return 0;
277 	else
278 		return buf;
279 }
280 
281 static int tpm_tis_i2c_ready(struct udevice *dev)
282 {
283 	struct tpm_chip *chip = dev_get_priv(dev);
284 	int rc;
285 
286 	/* This causes the current command to be aborted */
287 	u8 buf = TPM_STS_COMMAND_READY;
288 
289 	debug("%s\n", __func__);
290 	rc = tpm_tis_i2c_write_long(dev, TPM_STS(chip->locality), &buf, 1);
291 	if (rc)
292 		debug("%s: rc=%d\n", __func__, rc);
293 
294 	return rc;
295 }
296 
297 static ssize_t tpm_tis_i2c_get_burstcount(struct udevice *dev)
298 {
299 	struct tpm_chip *chip = dev_get_priv(dev);
300 	unsigned long start, stop;
301 	ssize_t burstcnt;
302 	u8 addr, buf[3];
303 
304 	/* Wait for burstcount */
305 	/* XXX: Which timeout value? Spec has 2 answers (c & d) */
306 	start = get_timer(0);
307 	stop = chip->timeout_d;
308 	do {
309 		/* Note: STS is little endian */
310 		addr = TPM_STS(chip->locality) + 1;
311 		if (tpm_tis_i2c_read(dev, addr, buf, 3) < 0)
312 			burstcnt = 0;
313 		else
314 			burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
315 
316 		if (burstcnt)
317 			return burstcnt;
318 		mdelay(TPM_TIMEOUT_MS);
319 	} while (get_timer(start) < stop);
320 
321 	return -EBUSY;
322 }
323 
324 static int tpm_tis_i2c_wait_for_stat(struct udevice *dev, u8 mask,
325 				     unsigned long timeout, int *status)
326 {
327 	unsigned long start, stop;
328 
329 	/* Check current status */
330 	*status = tpm_tis_i2c_status(dev);
331 	if ((*status & mask) == mask)
332 		return 0;
333 
334 	start = get_timer(0);
335 	stop = timeout;
336 	do {
337 		mdelay(TPM_TIMEOUT_MS);
338 		*status = tpm_tis_i2c_status(dev);
339 		if ((*status & mask) == mask)
340 			return 0;
341 	} while (get_timer(start) < stop);
342 
343 	return -ETIMEDOUT;
344 }
345 
346 static int tpm_tis_i2c_recv_data(struct udevice *dev, u8 *buf, size_t count)
347 {
348 	struct tpm_chip *chip = dev_get_priv(dev);
349 	size_t size = 0;
350 	ssize_t burstcnt;
351 	int rc;
352 
353 	while (size < count) {
354 		burstcnt = tpm_tis_i2c_get_burstcount(dev);
355 
356 		/* burstcount < 0 -> tpm is busy */
357 		if (burstcnt < 0)
358 			return burstcnt;
359 
360 		/* Limit received data to max left */
361 		if (burstcnt > (count - size))
362 			burstcnt = count - size;
363 
364 		rc = tpm_tis_i2c_read(dev, TPM_DATA_FIFO(chip->locality),
365 				      &(buf[size]), burstcnt);
366 		if (rc == 0)
367 			size += burstcnt;
368 	}
369 
370 	return size;
371 }
372 
373 static int tpm_tis_i2c_recv(struct udevice *dev, u8 *buf, size_t count)
374 {
375 	struct tpm_chip *chip = dev_get_priv(dev);
376 	int size = 0;
377 	int expected, status;
378 	int rc;
379 
380 	status = tpm_tis_i2c_status(dev);
381 	if (status == TPM_STS_COMMAND_READY)
382 		return -EINTR;
383 	if ((status & (TPM_STS_DATA_AVAIL | TPM_STS_VALID)) !=
384 	    (TPM_STS_DATA_AVAIL | TPM_STS_VALID))
385 		return -EAGAIN;
386 
387 	debug("...got it;\n");
388 
389 	/* Read first 10 bytes, including tag, paramsize, and result */
390 	size = tpm_tis_i2c_recv_data(dev, buf, TPM_HEADER_SIZE);
391 	if (size < TPM_HEADER_SIZE) {
392 		debug("Unable to read header\n");
393 		return size < 0 ? size : -EIO;
394 	}
395 
396 	expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);
397 	if ((size_t)expected > count) {
398 		debug("Error size=%x, expected=%x, count=%x\n", size, expected,
399 		      count);
400 		return -ENOSPC;
401 	}
402 
403 	size += tpm_tis_i2c_recv_data(dev, &buf[TPM_HEADER_SIZE],
404 				      expected - TPM_HEADER_SIZE);
405 	if (size < expected) {
406 		debug("Unable to read remainder of result\n");
407 		return -ETIMEDOUT;
408 	}
409 
410 	rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID, chip->timeout_c,
411 				       &status);
412 	if (rc)
413 		return rc;
414 	if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
415 		debug("Error left over data\n");
416 		return -EIO;
417 	}
418 
419 	return size;
420 }
421 
422 static int tpm_tis_i2c_send(struct udevice *dev, const u8 *buf, size_t len)
423 {
424 	struct tpm_chip *chip = dev_get_priv(dev);
425 	int rc, status;
426 	size_t burstcnt;
427 	size_t count = 0;
428 	int retry = 0;
429 	u8 sts = TPM_STS_GO;
430 
431 	debug("%s: len=%d\n", __func__, len);
432 	if (len > TPM_DEV_BUFSIZE)
433 		return -E2BIG;  /* Command is too long for our tpm, sorry */
434 
435 	if (tpm_tis_i2c_request_locality(dev, 0) < 0)
436 		return -EBUSY;
437 
438 	status = tpm_tis_i2c_status(dev);
439 	if ((status & TPM_STS_COMMAND_READY) == 0) {
440 		rc = tpm_tis_i2c_ready(dev);
441 		if (rc)
442 			return rc;
443 		rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_COMMAND_READY,
444 					       chip->timeout_b, &status);
445 		if (rc)
446 			return rc;
447 	}
448 
449 	burstcnt = tpm_tis_i2c_get_burstcount(dev);
450 
451 	/* burstcount < 0 -> tpm is busy */
452 	if (burstcnt < 0)
453 		return burstcnt;
454 
455 	while (count < len) {
456 		udelay(300);
457 		if (burstcnt > len - count)
458 			burstcnt = len - count;
459 
460 #ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION
461 		if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN)
462 			burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN;
463 #endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */
464 
465 		rc = tpm_tis_i2c_write(dev, TPM_DATA_FIFO(chip->locality),
466 				       &(buf[count]), burstcnt);
467 		if (rc == 0)
468 			count += burstcnt;
469 		else {
470 			debug("%s: error\n", __func__);
471 			if (retry++ > 10)
472 				return -EIO;
473 			rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID,
474 						       chip->timeout_c,
475 						       &status);
476 			if (rc)
477 				return rc;
478 
479 			if ((status & TPM_STS_DATA_EXPECT) == 0)
480 				return -EIO;
481 		}
482 	}
483 
484 	/* Go and do it */
485 	rc = tpm_tis_i2c_write(dev, TPM_STS(chip->locality), &sts, 1);
486 	if (rc < 0)
487 		return rc;
488 	debug("%s: done, rc=%d\n", __func__, rc);
489 
490 	return len;
491 }
492 
493 static int tpm_tis_i2c_cleanup(struct udevice *dev)
494 {
495 	struct tpm_chip *chip = dev_get_priv(dev);
496 
497 	tpm_tis_i2c_ready(dev);
498 	/*
499 	 * The TPM needs some time to clean up here,
500 	 * so we sleep rather than keeping the bus busy
501 	 */
502 	mdelay(2);
503 	tpm_tis_i2c_release_locality(dev, chip->locality, 0);
504 
505 	return 0;
506 }
507 
508 static int tpm_tis_i2c_init(struct udevice *dev)
509 {
510 	struct tpm_chip *chip = dev_get_priv(dev);
511 	u32 vendor;
512 	u32 expected_did_vid;
513 	int rc;
514 
515 	chip->is_open = 1;
516 
517 	/* Default timeouts - these could move to the device tree */
518 	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
519 	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
520 	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
521 	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;
522 
523 	rc = tpm_tis_i2c_request_locality(dev, 0);
524 	if (rc < 0)
525 		return rc;
526 
527 	/* Read four bytes from DID_VID register */
528 	if (tpm_tis_i2c_read(dev, TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
529 		tpm_tis_i2c_release_locality(dev, 0, 1);
530 		return -EIO;
531 	}
532 
533 	if (chip->chip_type == SLB9635) {
534 		vendor = be32_to_cpu(vendor);
535 		expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
536 	} else {
537 		/* device id and byte order has changed for newer i2c tpms */
538 		expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
539 	}
540 
541 	if (chip->chip_type != UNKNOWN && vendor != expected_did_vid) {
542 		error("Vendor id did not match! ID was %08x\n", vendor);
543 		return -ENODEV;
544 	}
545 
546 	chip->vend_dev = vendor;
547 	debug("1.2 TPM (chip type %s device-id 0x%X)\n",
548 	      chip_name[chip->chip_type], vendor >> 16);
549 
550 	/*
551 	 * A timeout query to TPM can be placed here.
552 	 * Standard timeout values are used so far
553 	 */
554 
555 	return 0;
556 }
557 
558 static int tpm_tis_i2c_open(struct udevice *dev)
559 {
560 	struct tpm_chip *chip = dev_get_priv(dev);
561 	int rc;
562 
563 	debug("%s: start\n", __func__);
564 	if (chip->is_open)
565 		return -EBUSY;
566 	rc = tpm_tis_i2c_init(dev);
567 	if (rc < 0)
568 		chip->is_open = 0;
569 
570 	return rc;
571 }
572 
573 static int tpm_tis_i2c_close(struct udevice *dev)
574 {
575 	struct tpm_chip *chip = dev_get_priv(dev);
576 
577 	if (chip->is_open) {
578 		tpm_tis_i2c_release_locality(dev, chip->locality, 1);
579 		chip->is_open = 0;
580 		chip->vend_dev = 0;
581 	}
582 
583 	return 0;
584 }
585 
586 static int tpm_tis_get_desc(struct udevice *dev, char *buf, int size)
587 {
588 	struct tpm_chip *chip = dev_get_priv(dev);
589 
590 	if (size < 50)
591 		return -ENOSPC;
592 
593 	return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
594 			chip->is_open ? "open" : "closed",
595 			chip_name[chip->chip_type],
596 			chip->vend_dev >> 16);
597 }
598 
599 static int tpm_tis_i2c_probe(struct udevice *dev)
600 {
601 	struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);
602 	struct tpm_chip *chip = dev_get_priv(dev);
603 
604 	chip->chip_type = dev_get_driver_data(dev);
605 
606 	/* TODO: These need to be checked and tuned */
607 	uc_priv->duration_ms[TPM_SHORT] = TIS_SHORT_TIMEOUT_MS;
608 	uc_priv->duration_ms[TPM_MEDIUM] = TIS_LONG_TIMEOUT_MS;
609 	uc_priv->duration_ms[TPM_LONG] = TIS_LONG_TIMEOUT_MS;
610 	uc_priv->retry_time_ms = TPM_TIMEOUT_MS;
611 
612 	return 0;
613 }
614 
615 static const struct tpm_ops tpm_tis_i2c_ops = {
616 	.open		= tpm_tis_i2c_open,
617 	.close		= tpm_tis_i2c_close,
618 	.get_desc	= tpm_tis_get_desc,
619 	.send		= tpm_tis_i2c_send,
620 	.recv		= tpm_tis_i2c_recv,
621 	.cleanup	= tpm_tis_i2c_cleanup,
622 };
623 
624 static const struct udevice_id tpm_tis_i2c_ids[] = {
625 	{ .compatible = "infineon,slb9635tt", .data = SLB9635 },
626 	{ .compatible = "infineon,slb9645tt", .data = SLB9645 },
627 	{ }
628 };
629 
630 U_BOOT_DRIVER(tpm_tis_i2c) = {
631 	.name   = "tpm_tis_infineon",
632 	.id     = UCLASS_TPM,
633 	.of_match = tpm_tis_i2c_ids,
634 	.ops    = &tpm_tis_i2c_ops,
635 	.probe	= tpm_tis_i2c_probe,
636 	.priv_auto_alloc_size = sizeof(struct tpm_chip),
637 };
638