1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Cr50 / H1 TPM support
4  *
5  * Copyright 2018 Google LLC
6  */
7 
8 #define LOG_CATEGORY UCLASS_TPM
9 
10 #include <common.h>
11 #include <dm.h>
12 #include <i2c.h>
13 #include <irq.h>
14 #include <log.h>
15 #include <spl.h>
16 #include <tpm-v2.h>
17 #include <acpi/acpigen.h>
18 #include <acpi/acpi_device.h>
19 #include <asm/gpio.h>
20 #include <asm/io.h>
21 #include <asm/arch/iomap.h>
22 #include <asm/arch/pm.h>
23 #include <linux/delay.h>
24 #include <dm/acpi.h>
25 
26 enum {
27 	TIMEOUT_INIT_MS		= 30000, /* Very long timeout for TPM init */
28 	TIMEOUT_LONG_US		= 2 * 1000 * 1000,
29 	TIMEOUT_SHORT_US	= 2 * 1000,
30 	TIMEOUT_NO_IRQ_US	= 20 * 1000,
31 	TIMEOUT_IRQ_US		= 100 * 1000,
32 };
33 
34 enum {
35 	CR50_DID_VID = 0x00281ae0L
36 };
37 
38 enum {
39 	CR50_MAX_BUF_SIZE = 63,
40 };
41 
42 /**
43  * struct cr50_priv - Private driver data
44  *
45  * @ready_gpio: GPIO to use to check if the TPM is ready
46  * @irq: IRQ to use check if the TPM is ready (has priority over @ready_gpio)
47  * @locality: Currenttly claimed locality (-1 if none)
48  * @vendor: vendor: Vendor ID for TPM
49  * @use_irq: true to use @irq, false to use @ready if available
50  */
51 struct cr50_priv {
52 	struct gpio_desc ready_gpio;
53 	struct irq irq;
54 	int locality;
55 	uint vendor;
56 	bool use_irq;
57 };
58 
59 /* Wait for interrupt to indicate TPM is ready */
cr50_i2c_wait_tpm_ready(struct udevice * dev)60 static int cr50_i2c_wait_tpm_ready(struct udevice *dev)
61 {
62 	struct cr50_priv *priv = dev_get_priv(dev);
63 	ulong timeout, base;
64 	int i;
65 
66 	if (!priv->use_irq && !dm_gpio_is_valid(&priv->ready_gpio)) {
67 		/* Fixed delay if interrupt not supported */
68 		udelay(TIMEOUT_NO_IRQ_US);
69 		return 0;
70 	}
71 
72 	base = timer_get_us();
73 	timeout = base + TIMEOUT_IRQ_US;
74 
75 	i = 0;
76 	while (priv->use_irq ? !irq_read_and_clear(&priv->irq) :
77 	       !dm_gpio_get_value(&priv->ready_gpio)) {
78 		i++;
79 		if ((int)(timer_get_us() - timeout) >= 0) {
80 			log_warning("Timeout\n");
81 			/* Use this instead of the -ETIMEDOUT used by i2c */
82 			return -ETIME;
83 		}
84 	}
85 	log_debug("i=%d\n", i);
86 
87 	return 0;
88 }
89 
90 /* Clear pending interrupts */
cr50_i2c_clear_tpm_irq(struct udevice * dev)91 static void cr50_i2c_clear_tpm_irq(struct udevice *dev)
92 {
93 	struct cr50_priv *priv = dev_get_priv(dev);
94 
95 	if (priv->use_irq)
96 		irq_read_and_clear(&priv->irq);
97 }
98 
99 /*
100  * cr50_i2c_read() - read from TPM register
101  *
102  * @dev: TPM chip information
103  * @addr: register address to read from
104  * @buffer: provided by caller
105  * @len: number of bytes to read
106  *
107  * 1) send register address byte 'addr' to the TPM
108  * 2) wait for TPM to indicate it is ready
109  * 3) read 'len' bytes of TPM response into the provided 'buffer'
110  *
111  * Return 0 on success. -ve on error
112  */
cr50_i2c_read(struct udevice * dev,u8 addr,u8 * buffer,size_t len)113 static int cr50_i2c_read(struct udevice *dev, u8 addr, u8 *buffer,
114 			 size_t len)
115 {
116 	int ret;
117 
118 	/* Clear interrupt before starting transaction */
119 	cr50_i2c_clear_tpm_irq(dev);
120 
121 	/* Send the register address byte to the TPM */
122 	ret = dm_i2c_write(dev, 0, &addr, 1);
123 	if (ret) {
124 		log_err("Address write failed (err=%d)\n", ret);
125 		return ret;
126 	}
127 
128 	/* Wait for TPM to be ready with response data */
129 	ret = cr50_i2c_wait_tpm_ready(dev);
130 	if (ret)
131 		return ret;
132 
133 	/* Read response data frrom the TPM */
134 	ret = dm_i2c_read(dev, 0, buffer, len);
135 	if (ret) {
136 		log_err("Read response failed (err=%d)\n", ret);
137 		return ret;
138 	}
139 
140 	return 0;
141 }
142 
143 /*
144  * cr50_i2c_write() - write to TPM register
145  *
146  * @dev: TPM chip information
147  * @addr: register address to write to
148  * @buffer: data to write
149  * @len: number of bytes to write
150  *
151  * 1) prepend the provided address to the provided data
152  * 2) send the address+data to the TPM
153  * 3) wait for TPM to indicate it is done writing
154  *
155  * Returns -1 on error, 0 on success.
156  */
cr50_i2c_write(struct udevice * dev,u8 addr,const u8 * buffer,size_t len)157 static int cr50_i2c_write(struct udevice *dev, u8 addr, const u8 *buffer,
158 			  size_t len)
159 {
160 	u8 buf[len + 1];
161 	int ret;
162 
163 	if (len > CR50_MAX_BUF_SIZE) {
164 		log_err("Length %zd is too large\n", len);
165 		return -E2BIG;
166 	}
167 
168 	/* Prepend the 'register address' to the buffer */
169 	buf[0] = addr;
170 	memcpy(buf + 1, buffer, len);
171 
172 	/* Clear interrupt before starting transaction */
173 	cr50_i2c_clear_tpm_irq(dev);
174 
175 	/* Send write request buffer with address */
176 	ret = dm_i2c_write(dev, 0, buf, len + 1);
177 	if (ret) {
178 		log_err("Error writing to TPM (err=%d)\n", ret);
179 		return ret;
180 	}
181 
182 	/* Wait for TPM to be ready */
183 	return cr50_i2c_wait_tpm_ready(dev);
184 }
185 
tpm_access(int locality)186 static inline u8 tpm_access(int locality)
187 {
188 	if (locality == -1)
189 		locality = 0;
190 	return 0x0 | (locality << 4);
191 }
192 
tpm_sts(int locality)193 static inline u8 tpm_sts(int locality)
194 {
195 	if (locality == -1)
196 		locality = 0;
197 	return 0x1 | (locality << 4);
198 }
199 
tpm_data_fifo(int locality)200 static inline u8 tpm_data_fifo(int locality)
201 {
202 	if (locality == -1)
203 		locality = 0;
204 	return 0x5 | (locality << 4);
205 }
206 
tpm_did_vid(int locality)207 static inline u8 tpm_did_vid(int locality)
208 {
209 	if (locality == -1)
210 		locality = 0;
211 	return 0x6 | (locality << 4);
212 }
213 
release_locality(struct udevice * dev,int force)214 static int release_locality(struct udevice *dev, int force)
215 {
216 	struct cr50_priv *priv = dev_get_priv(dev);
217 	u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_PENDING;
218 	u8 addr = tpm_access(priv->locality);
219 	int ret;
220 	u8 buf;
221 
222 	ret = cr50_i2c_read(dev, addr, &buf, 1);
223 	if (ret)
224 		return ret;
225 
226 	if (force || (buf & mask) == mask) {
227 		buf = TPM_ACCESS_ACTIVE_LOCALITY;
228 		cr50_i2c_write(dev, addr, &buf, 1);
229 	}
230 
231 	priv->locality = -1;
232 
233 	return 0;
234 }
235 
236 /* cr50 requires all 4 bytes of status register to be read */
cr50_i2c_status(struct udevice * dev)237 static int cr50_i2c_status(struct udevice *dev)
238 {
239 	struct cr50_priv *priv = dev_get_priv(dev);
240 	u8 buf[4];
241 	int ret;
242 
243 	ret = cr50_i2c_read(dev, tpm_sts(priv->locality), buf, sizeof(buf));
244 	if (ret) {
245 		log_warning("%s: Failed to read status\n", __func__);
246 		return ret;
247 	}
248 
249 	return buf[0];
250 }
251 
252 /* cr50 requires all 4 bytes of status register to be written */
cr50_i2c_ready(struct udevice * dev)253 static int cr50_i2c_ready(struct udevice *dev)
254 {
255 	struct cr50_priv *priv = dev_get_priv(dev);
256 	u8 buf[4] = { TPM_STS_COMMAND_READY };
257 	int ret;
258 
259 	ret = cr50_i2c_write(dev, tpm_sts(priv->locality), buf, sizeof(buf));
260 	if (ret)
261 		return ret;
262 
263 	udelay(TIMEOUT_SHORT_US);
264 
265 	return 0;
266 }
267 
cr50_i2c_wait_burststs(struct udevice * dev,u8 mask,size_t * burst,int * status)268 static int cr50_i2c_wait_burststs(struct udevice *dev, u8 mask,
269 				  size_t *burst, int *status)
270 {
271 	struct cr50_priv *priv = dev_get_priv(dev);
272 	ulong timeout;
273 	u32 buf;
274 
275 	/*
276 	 * cr50 uses bytes 3:2 of status register for burst count and all 4
277 	 * bytes must be read
278 	 */
279 	timeout = timer_get_us() + TIMEOUT_LONG_US;
280 	while (timer_get_us() < timeout) {
281 		if (cr50_i2c_read(dev, tpm_sts(priv->locality),
282 				  (u8 *)&buf, sizeof(buf)) < 0) {
283 			udelay(TIMEOUT_SHORT_US);
284 			continue;
285 		}
286 
287 		*status = buf & 0xff;
288 		*burst = le16_to_cpu((buf >> 8) & 0xffff);
289 
290 		if ((*status & mask) == mask &&
291 		    *burst > 0 && *burst <= CR50_MAX_BUF_SIZE)
292 			return 0;
293 
294 		udelay(TIMEOUT_SHORT_US);
295 	}
296 
297 	log_warning("Timeout reading burst and status\n");
298 
299 	return -ETIMEDOUT;
300 }
301 
cr50_i2c_recv(struct udevice * dev,u8 * buf,size_t buf_len)302 static int cr50_i2c_recv(struct udevice *dev, u8 *buf, size_t buf_len)
303 {
304 	struct cr50_priv *priv = dev_get_priv(dev);
305 	size_t burstcnt, expected, current, len;
306 	u8 addr = tpm_data_fifo(priv->locality);
307 	u8 mask = TPM_STS_VALID | TPM_STS_DATA_AVAIL;
308 	u32 expected_buf;
309 	int status;
310 	int ret;
311 
312 	log_debug("%s: len=%x\n", __func__, buf_len);
313 	if (buf_len < TPM_HEADER_SIZE)
314 		return -E2BIG;
315 
316 	ret = cr50_i2c_wait_burststs(dev, mask, &burstcnt, &status);
317 	if (ret < 0) {
318 		log_warning("First chunk not available\n");
319 		goto out_err;
320 	}
321 
322 	/* Read first chunk of burstcnt bytes */
323 	if (cr50_i2c_read(dev, addr, buf, burstcnt) < 0) {
324 		log_warning("Read failed\n");
325 		goto out_err;
326 	}
327 
328 	/* Determine expected data in the return buffer */
329 	memcpy(&expected_buf, buf + TPM_CMD_COUNT_OFFSET, sizeof(expected_buf));
330 	expected = be32_to_cpu(expected_buf);
331 	if (expected > buf_len) {
332 		log_warning("Too much data: %zu > %zu\n", expected, buf_len);
333 		goto out_err;
334 	}
335 
336 	/* Now read the rest of the data */
337 	current = burstcnt;
338 	while (current < expected) {
339 		/* Read updated burst count and check status */
340 		if (cr50_i2c_wait_burststs(dev, mask, &burstcnt, &status) < 0) {
341 			log_warning("- burst failure1\n");
342 			goto out_err;
343 			}
344 
345 		len = min(burstcnt, expected - current);
346 		if (cr50_i2c_read(dev, addr, buf + current, len) != 0) {
347 			log_warning("Read failed\n");
348 			goto out_err;
349 		}
350 
351 		current += len;
352 	}
353 
354 	if (cr50_i2c_wait_burststs(dev, TPM_STS_VALID, &burstcnt,
355 				   &status) < 0) {
356 		log_warning("- burst failure2\n");
357 		goto out_err;
358 	}
359 	if (status & TPM_STS_DATA_AVAIL) {
360 		log_warning("Data still available\n");
361 		goto out_err;
362 	}
363 
364 	return current;
365 
366 out_err:
367 	/* Abort current transaction if still pending */
368 	ret = cr50_i2c_status(dev);
369 	if (ret < 0)
370 		return ret;
371 	if (ret & TPM_STS_COMMAND_READY) {
372 		ret = cr50_i2c_ready(dev);
373 		if (ret)
374 			return ret;
375 	}
376 
377 	return -EIO;
378 }
379 
cr50_i2c_send(struct udevice * dev,const u8 * buf,size_t len)380 static int cr50_i2c_send(struct udevice *dev, const u8 *buf, size_t len)
381 {
382 	struct cr50_priv *priv = dev_get_priv(dev);
383 	int status;
384 	size_t burstcnt, limit, sent = 0;
385 	u8 tpm_go[4] = { TPM_STS_GO };
386 	ulong timeout;
387 	int ret;
388 
389 	log_debug("%s: len=%x\n", __func__, len);
390 	timeout = timer_get_us() + TIMEOUT_LONG_US;
391 	do {
392 		ret = cr50_i2c_status(dev);
393 		if (ret < 0)
394 			goto out_err;
395 		if (ret & TPM_STS_COMMAND_READY)
396 			break;
397 
398 		if (timer_get_us() > timeout)
399 			goto out_err;
400 
401 		ret = cr50_i2c_ready(dev);
402 		if (ret)
403 			goto out_err;
404 	} while (1);
405 
406 	while (len > 0) {
407 		u8 mask = TPM_STS_VALID;
408 
409 		/* Wait for data if this is not the first chunk */
410 		if (sent > 0)
411 			mask |= TPM_STS_DATA_EXPECT;
412 
413 		if (cr50_i2c_wait_burststs(dev, mask, &burstcnt, &status) < 0)
414 			goto out_err;
415 
416 		/*
417 		 * Use burstcnt - 1 to account for the address byte
418 		 * that is inserted by cr50_i2c_write()
419 		 */
420 		limit = min(burstcnt - 1, len);
421 		if (cr50_i2c_write(dev, tpm_data_fifo(priv->locality),
422 				   &buf[sent], limit) != 0) {
423 			log_warning("Write failed\n");
424 			goto out_err;
425 		}
426 
427 		sent += limit;
428 		len -= limit;
429 	}
430 
431 	/* Ensure TPM is not expecting more data */
432 	if (cr50_i2c_wait_burststs(dev, TPM_STS_VALID, &burstcnt, &status) < 0)
433 		goto out_err;
434 	if (status & TPM_STS_DATA_EXPECT) {
435 		log_warning("Data still expected\n");
436 		goto out_err;
437 	}
438 
439 	/* Start the TPM command */
440 	ret = cr50_i2c_write(dev, tpm_sts(priv->locality), tpm_go,
441 			     sizeof(tpm_go));
442 	if (ret) {
443 		log_warning("Start command failed\n");
444 		goto out_err;
445 	}
446 
447 	return sent;
448 
449 out_err:
450 	/* Abort current transaction if still pending */
451 	ret = cr50_i2c_status(dev);
452 
453 	if (ret < 0 || (ret & TPM_STS_COMMAND_READY)) {
454 		ret = cr50_i2c_ready(dev);
455 		if (ret)
456 			return ret;
457 	}
458 
459 	return -EIO;
460 }
461 
462 /**
463  * process_reset() - Wait for the Cr50 to reset
464  *
465  * Cr50 processes reset requests asynchronously and conceivably could be busy
466  * executing a long command and not reacting to the reset pulse for a while.
467  *
468  * This function will make sure that the AP does not proceed with boot until
469  * TPM finished reset processing.
470  *
471  * @dev: Cr50 device
472  * @return 0 if OK, -EPERM if locality could not be taken
473  */
process_reset(struct udevice * dev)474 static int process_reset(struct udevice *dev)
475 {
476 	const int loc = 0;
477 	u8 access;
478 	ulong start;
479 
480 	/*
481 	 * Locality is released by TPM reset.
482 	 *
483 	 * If locality is taken at this point, this could be due to the fact
484 	 * that the TPM is performing a long operation and has not processed
485 	 * reset request yet. We'll wait up to CR50_TIMEOUT_INIT_MS and see if
486 	 * it releases locality when reset is processed.
487 	 */
488 	start = get_timer(0);
489 	do {
490 		const u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
491 		int ret;
492 
493 		ret = cr50_i2c_read(dev, tpm_access(loc),
494 				    &access, sizeof(access));
495 		if (ret || ((access & mask) == mask)) {
496 			/*
497 			 * Don't bombard the chip with traffic; let it keep
498 			 * processing the command.
499 			 */
500 			mdelay(2);
501 			continue;
502 		}
503 
504 		log_debug("TPM ready after %ld ms\n", get_timer(start));
505 
506 		return 0;
507 	} while (get_timer(start) < TIMEOUT_INIT_MS);
508 
509 	log_err("TPM failed to reset after %ld ms, status: %#x\n",
510 		get_timer(start), access);
511 
512 	return -EPERM;
513 }
514 
515 /*
516  * Locality could be already claimed (if this is a later U-Boot phase and the
517  * read-only U-Boot did not release it), or not yet claimed, if this is TPL or
518  * the older read-only U-Boot did release it.
519  */
claim_locality(struct udevice * dev,int loc)520 static int claim_locality(struct udevice *dev, int loc)
521 {
522 	const u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
523 	struct cr50_priv *priv = dev_get_priv(dev);
524 	u8 access;
525 	int ret;
526 
527 	ret = cr50_i2c_read(dev, tpm_access(loc), &access, sizeof(access));
528 	if (ret)
529 		return log_msg_ret("read1", ret);
530 
531 	if ((access & mask) == mask) {
532 		log_warning("Locality already claimed\n");
533 		return 0;
534 	}
535 
536 	access = TPM_ACCESS_REQUEST_USE;
537 	ret = cr50_i2c_write(dev, tpm_access(loc), &access, sizeof(access));
538 	if (ret)
539 		return log_msg_ret("write", ret);
540 
541 	ret = cr50_i2c_read(dev, tpm_access(loc), &access, sizeof(access));
542 	if (ret)
543 		return log_msg_ret("read2", ret);
544 
545 	if ((access & mask) != mask) {
546 		log_err("Failed to claim locality\n");
547 		return -EPERM;
548 	}
549 	log_debug("Claimed locality %d\n", loc);
550 	priv->locality = loc;
551 
552 	return 0;
553 }
554 
cr50_i2c_get_desc(struct udevice * dev,char * buf,int size)555 static int cr50_i2c_get_desc(struct udevice *dev, char *buf, int size)
556 {
557 	struct dm_i2c_chip *chip = dev_get_parent_plat(dev);
558 	struct cr50_priv *priv = dev_get_priv(dev);
559 	int len;
560 
561 	len = snprintf(buf, size, "cr50 TPM 2.0 (i2c %02x id %x), ",
562 		       chip->chip_addr, priv->vendor >> 16);
563 	if (priv->use_irq) {
564 		len += snprintf(buf + len, size - len, "irq=%s/%ld",
565 				priv->irq.dev->name, priv->irq.id);
566 	} else if (dm_gpio_is_valid(&priv->ready_gpio)) {
567 		len += snprintf(buf + len, size - len, "gpio=%s/%u",
568 				priv->ready_gpio.dev->name,
569 				priv->ready_gpio.offset);
570 	} else {
571 		len += snprintf(buf + len, size - len, "delay=%d",
572 				TIMEOUT_NO_IRQ_US);
573 	}
574 
575 	return len;
576 }
577 
cr50_i2c_open(struct udevice * dev)578 static int cr50_i2c_open(struct udevice *dev)
579 {
580 	char buf[80];
581 	int ret;
582 
583 	ret = process_reset(dev);
584 	if (ret)
585 		return log_msg_ret("reset", ret);
586 
587 	ret = claim_locality(dev, 0);
588 	if (ret)
589 		return log_msg_ret("claim", ret);
590 
591 	cr50_i2c_get_desc(dev, buf, sizeof(buf));
592 	log_debug("%s\n", buf);
593 
594 	return 0;
595 }
596 
cr50_i2c_cleanup(struct udevice * dev)597 static int cr50_i2c_cleanup(struct udevice *dev)
598 {
599 	struct cr50_priv *priv = dev_get_priv(dev);
600 
601 	log_debug("cleanup %d\n", priv->locality);
602 	if (priv->locality != -1)
603 		release_locality(dev, 1);
604 
605 	return 0;
606 }
607 
cr50_acpi_fill_ssdt(const struct udevice * dev,struct acpi_ctx * ctx)608 static int cr50_acpi_fill_ssdt(const struct udevice *dev, struct acpi_ctx *ctx)
609 {
610 	char scope[ACPI_PATH_MAX];
611 	char name[ACPI_NAME_MAX];
612 	const char *hid;
613 	int ret;
614 
615 	ret = acpi_device_scope(dev, scope, sizeof(scope));
616 	if (ret)
617 		return log_msg_ret("scope", ret);
618 	ret = acpi_get_name(dev, name);
619 	if (ret)
620 		return log_msg_ret("name", ret);
621 
622 	hid = dev_read_string(dev, "acpi,hid");
623 	if (!hid)
624 		return log_msg_ret("hid", ret);
625 
626 	/* Device */
627 	acpigen_write_scope(ctx, scope);
628 	acpigen_write_device(ctx, name);
629 	acpigen_write_name_string(ctx, "_HID", hid);
630 	acpigen_write_name_integer(ctx, "_UID",
631 				   dev_read_u32_default(dev, "acpi,uid", 0));
632 	acpigen_write_name_string(ctx, "_DDN",
633 				  dev_read_string(dev, "acpi,ddn"));
634 	acpigen_write_sta(ctx, acpi_device_status(dev));
635 
636 	/* Resources */
637 	acpigen_write_name(ctx, "_CRS");
638 	acpigen_write_resourcetemplate_header(ctx);
639 	ret = acpi_device_write_i2c_dev(ctx, dev);
640 	if (ret < 0)
641 		return log_msg_ret("i2c", ret);
642 	ret = acpi_device_write_interrupt_or_gpio(ctx, (struct udevice *)dev,
643 						  "ready-gpios");
644 	if (ret < 0)
645 		return log_msg_ret("irq_gpio", ret);
646 
647 	acpigen_write_resourcetemplate_footer(ctx);
648 
649 	acpigen_pop_len(ctx); /* Device */
650 	acpigen_pop_len(ctx); /* Scope */
651 
652 	return 0;
653 }
654 
655 enum {
656 	TPM_TIMEOUT_MS		= 5,
657 	SHORT_TIMEOUT_MS	= 750,
658 	LONG_TIMEOUT_MS		= 2000,
659 };
660 
cr50_i2c_of_to_plat(struct udevice * dev)661 static int cr50_i2c_of_to_plat(struct udevice *dev)
662 {
663 	struct tpm_chip_priv *upriv = dev_get_uclass_priv(dev);
664 	struct cr50_priv *priv = dev_get_priv(dev);
665 	struct irq irq;
666 	int ret;
667 
668 	upriv->version = TPM_V2;
669 	upriv->duration_ms[TPM_SHORT] = SHORT_TIMEOUT_MS;
670 	upriv->duration_ms[TPM_MEDIUM] = LONG_TIMEOUT_MS;
671 	upriv->duration_ms[TPM_LONG] = LONG_TIMEOUT_MS;
672 	upriv->retry_time_ms = TPM_TIMEOUT_MS;
673 
674 	upriv->pcr_count = 32;
675 	upriv->pcr_select_min = 2;
676 
677 	/* Optional GPIO to track when cr50 is ready */
678 	ret = irq_get_by_index(dev, 0, &irq);
679 	if (!ret) {
680 		priv->irq = irq;
681 		priv->use_irq = true;
682 	} else {
683 		ret = gpio_request_by_name(dev, "ready-gpios", 0,
684 					   &priv->ready_gpio, GPIOD_IS_IN);
685 		if (ret) {
686 			log_warning("Cr50 does not have an ready GPIO/interrupt (err=%d)\n",
687 				    ret);
688 		}
689 	}
690 
691 	return 0;
692 }
693 
cr50_i2c_probe(struct udevice * dev)694 static int cr50_i2c_probe(struct udevice *dev)
695 {
696 	struct cr50_priv *priv = dev_get_priv(dev);
697 	u32 vendor = 0;
698 	ulong start;
699 
700 	/*
701 	 * 150ms should be enough to synchronise with the TPM even under the
702 	 * worst nested-reset-request conditions. In the vast majority of cases
703 	 * there will be no wait at all.
704 	 */
705 	start = get_timer(0);
706 	while (get_timer(start) < 150) {
707 		int ret;
708 
709 		/* Exit once DID and VID verified */
710 		ret = cr50_i2c_read(dev, tpm_did_vid(0), (u8 *)&vendor, 4);
711 		if (!ret && vendor == CR50_DID_VID)
712 			break;
713 
714 		/* TPM might be resetting; let's retry in a bit */
715 		mdelay(10);
716 	}
717 	if (vendor != CR50_DID_VID) {
718 		log_warning("DID_VID %08x not recognised\n", vendor);
719 		return log_msg_ret("vendor-id", -EXDEV);
720 	}
721 	priv->vendor = vendor;
722 	priv->locality = -1;
723 	log_debug("Cr50 ready\n");
724 
725 	return 0;
726 }
727 
728 struct acpi_ops cr50_acpi_ops = {
729 	.fill_ssdt	= cr50_acpi_fill_ssdt,
730 };
731 
732 static const struct tpm_ops cr50_i2c_ops = {
733 	.open		= cr50_i2c_open,
734 	.get_desc	= cr50_i2c_get_desc,
735 	.send		= cr50_i2c_send,
736 	.recv		= cr50_i2c_recv,
737 	.cleanup	= cr50_i2c_cleanup,
738 };
739 
740 static const struct udevice_id cr50_i2c_ids[] = {
741 	{ .compatible = "google,cr50" },
742 	{ }
743 };
744 
745 U_BOOT_DRIVER(google_cr50) = {
746 	.name   = "google_cr50",
747 	.id     = UCLASS_TPM,
748 	.of_match = cr50_i2c_ids,
749 	.ops    = &cr50_i2c_ops,
750 	.of_to_plat	= cr50_i2c_of_to_plat,
751 	.probe	= cr50_i2c_probe,
752 	.remove	= cr50_i2c_cleanup,
753 	.priv_auto	= sizeof(struct cr50_priv),
754 	ACPI_OPS_PTR(&cr50_acpi_ops)
755 	.flags		= DM_FLAG_OS_PREPARE,
756 };
757