drivers/tpm/tpm_tis_i2c.c

   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  * See file CREDITS for list of people who contributed to this
  21  * project.
  22  *
  23  * This program is free software; you can redistribute it and/or
  24  * modify it under the terms of the GNU General Public License as
  25  * published by the Free Software Foundation, version 2 of the
  26  * License.
  27  *
  28  * This program is distributed in the hope that it will be useful,
  29  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  31  * GNU General Public License for more details.
  32  *
  33  * You should have received a copy of the GNU General Public License
  34  * along with this program; if not, write to the Free Software
  35  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  36  * MA 02111-1307 USA
  37  */
  38
  39 #include <common.h>
  40 #include <fdtdec.h>
  41 #include <compiler.h>
  42 #include <i2c.h>
  43 #include <tpm.h>
  44 #include <asm-generic/errno.h>
  45 #include <linux/types.h>
  46 #include <linux/unaligned/be_byteshift.h>
  47
  48 #include "tpm_private.h"
  49
  50 DECLARE_GLOBAL_DATA_PTR;
  51
  52 /* Address of the TPM on the I2C bus */
  53 #define TPM_I2C_ADDR            0x20
  54
  55 /* Max buffer size supported by our tpm */
  56 #define TPM_DEV_BUFSIZE         1260
  57
  58 /* Max number of iterations after i2c NAK */
  59 #define MAX_COUNT               3
  60
  61 /*
  62  * Max number of iterations after i2c NAK for 'long' commands
  63  *
  64  * We need this especially for sending TPM_READY, since the cleanup after the
  65  * transtion to the ready state may take some time, but it is unpredictable
  66  * how long it will take.
  67  */
  68 #define MAX_COUNT_LONG          50
  69
  70 #define SLEEP_DURATION          60      /* in usec */
  71 #define SLEEP_DURATION_LONG     210     /* in usec */
  72
  73 #define TPM_HEADER_SIZE         10
  74
  75 /*
  76  * Expected value for DIDVID register
  77  *
  78  * The only device the system knows about at this moment is Infineon slb9635.
  79  */
  80 #define TPM_TIS_I2C_DID_VID     0x000b15d1L
  81
  82 enum tis_access {
  83         TPM_ACCESS_VALID                = 0x80,
  84         TPM_ACCESS_ACTIVE_LOCALITY      = 0x20,
  85         TPM_ACCESS_REQUEST_PENDING      = 0x04,
  86         TPM_ACCESS_REQUEST_USE          = 0x02,
  87 };
  88
  89 enum tis_status {
  90         TPM_STS_VALID                   = 0x80,
  91         TPM_STS_COMMAND_READY           = 0x40,
  92         TPM_STS_GO                      = 0x20,
  93         TPM_STS_DATA_AVAIL              = 0x10,
  94         TPM_STS_DATA_EXPECT             = 0x08,
  95 };
  96
  97 enum tis_defaults {
  98         TIS_SHORT_TIMEOUT               = 750,  /* ms */
  99         TIS_LONG_TIMEOUT                = 2000, /* ms */
 100 };
 101
 102 /* expected value for DIDVID register */
 103 #define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
 104 #define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L
 105
 106 enum i2c_chip_type {
 107         SLB9635,
 108         SLB9645,
 109         UNKNOWN,
 110 };
 111
 112 static const char * const chip_name[] = {
 113         [SLB9635] = "slb9635tt",
 114         [SLB9645] = "slb9645tt",
 115         [UNKNOWN] = "unknown/fallback to slb9635",
 116 };
 117
 118 #define TPM_ACCESS(l)                   (0x0000 | ((l) << 4))
 119 #define TPM_STS(l)                      (0x0001 | ((l) << 4))
 120 #define TPM_DATA_FIFO(l)                (0x0005 | ((l) << 4))
 121 #define TPM_DID_VID(l)                  (0x0006 | ((l) << 4))
 122
 123 /* Structure to store I2C TPM specific stuff */
 124 struct tpm_dev {
 125         uint addr;
 126         u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)];  /* Max buffer size + addr */
 127         enum i2c_chip_type chip_type;
 128 };
 129
 130 static struct tpm_dev tpm_dev = {
 131         .addr = TPM_I2C_ADDR
 132 };
 133
 134 static struct tpm_dev tpm_dev;
 135
 136 /*
 137  * iic_tpm_read() - read from TPM register
 138  * @addr: register address to read from
 139  * @buffer: provided by caller
 140  * @len: number of bytes to read
 141  *
 142  * Read len bytes from TPM register and put them into
 143  * buffer (little-endian format, i.e. first byte is put into buffer[0]).
 144  *
 145  * NOTE: TPM is big-endian for multi-byte values. Multi-byte
 146  * values have to be swapped.
 147  *
 148  * Return -EIO on error, 0 on success.
 149  */
 150 static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 151 {
 152         int rc;
 153         int count;
 154         uint32_t addrbuf = addr;
 155
 156         if ((tpm_dev.chip_type == SLB9635) || (tpm_dev.chip_type == UNKNOWN)) {
 157                 /* slb9635 protocol should work in both cases */
 158                 for (count = 0; count < MAX_COUNT; count++) {
 159                         rc = i2c_write(tpm_dev.addr, 0, 0,
 160                                        (uchar *)&addrbuf, 1);
 161                         if (rc == 0)
 162                                 break;  /* Success, break to skip sleep */
 163                         udelay(SLEEP_DURATION);
 164                 }
 165                 if (rc)
 166                         return -rc;
 167
 168                 /* After the TPM has successfully received the register address
 169                  * it needs some time, thus we're sleeping here again, before
 170                  * retrieving the data
 171                  */
 172                 for (count = 0; count < MAX_COUNT; count++) {
 173                         udelay(SLEEP_DURATION);
 174                         rc = i2c_read(tpm_dev.addr, 0, 0, buffer, len);
 175                         if (rc == 0)
 176                                 break;  /* success, break to skip sleep */
 177                 }
 178         } else {
 179                 /*
 180                  * Use a combined read for newer chips.
 181                  * Unfortunately the smbus functions are not suitable due to
 182                  * the 32 byte limit of the smbus.
 183                  * Retries should usually not be needed, but are kept just to
 184                  * be safe on the safe side.
 185                  */
 186                 for (count = 0; count < MAX_COUNT; count++) {
 187                         rc = i2c_read(tpm_dev.addr, addr, 1, buffer, len);
 188                         if (rc == 0)
 189                                 break;  /* break here to skip sleep */
 190                         udelay(SLEEP_DURATION);
 191                 }
 192         }
 193
 194         /* Take care of 'guard time' */
 195         udelay(SLEEP_DURATION);
 196         if (rc)
 197                 return -rc;
 198
 199         return 0;
 200 }
 201
 202 static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
 203                 unsigned int sleep_time, u8 max_count)
 204 {
 205         int rc = 0;
 206         int count;
 207
 208         /* Prepare send buffer */
 209         tpm_dev.buf[0] = addr;
 210         memcpy(&(tpm_dev.buf[1]), buffer, len);
 211
 212         for (count = 0; count < max_count; count++) {
 213                 rc = i2c_write(tpm_dev.addr, 0, 0, tpm_dev.buf, len + 1);
 214                 if (rc == 0)
 215                         break;  /* Success, break to skip sleep */
 216                 udelay(sleep_time);
 217         }
 218
 219         /* take care of 'guard time' */
 220         udelay(SLEEP_DURATION);
 221         if (rc)
 222                 return -rc;
 223
 224         return 0;
 225 }
 226
 227 /*
 228  * iic_tpm_write() - write to TPM register
 229  * @addr: register address to write to
 230  * @buffer: containing data to be written
 231  * @len: number of bytes to write
 232  *
 233  * Write len bytes from provided buffer to TPM register (little
 234  * endian format, i.e. buffer[0] is written as first byte).
 235  *
 236  * NOTE: TPM is big-endian for multi-byte values. Multi-byte
 237  * values have to be swapped.
 238  *
 239  * NOTE: use this function instead of the iic_tpm_write_generic function.
 240  *
 241  * Return -EIO on error, 0 on success
 242  */
 243 static int iic_tpm_write(u8 addr, u8 *buffer, size_t len)
 244 {
 245         return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION,
 246                         MAX_COUNT);
 247 }
 248
 249 /*
 250  * This function is needed especially for the cleanup situation after
 251  * sending TPM_READY
 252  */
 253 static int iic_tpm_write_long(u8 addr, u8 *buffer, size_t len)
 254 {
 255         return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG,
 256                         MAX_COUNT_LONG);
 257 }
 258
 259 static int check_locality(struct tpm_chip *chip, int loc)
 260 {
 261         const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
 262         u8 buf;
 263         int rc;
 264
 265         rc = iic_tpm_read(TPM_ACCESS(loc), &buf, 1);
 266         if (rc < 0)
 267                 return rc;
 268
 269         if ((buf & mask) == mask) {
 270                 chip->vendor.locality = loc;
 271                 return loc;
 272         }
 273
 274         return -1;
 275 }
 276
 277 static void release_locality(struct tpm_chip *chip, int loc, int force)
 278 {
 279         const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
 280         u8 buf;
 281
 282         if (iic_tpm_read(TPM_ACCESS(loc), &buf, 1) < 0)
 283                 return;
 284
 285         if (force || (buf & mask) == mask) {
 286                 buf = TPM_ACCESS_ACTIVE_LOCALITY;
 287                 iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
 288         }
 289 }
 290
 291 static int request_locality(struct tpm_chip *chip, int loc)
 292 {
 293         unsigned long start, stop;
 294         u8 buf = TPM_ACCESS_REQUEST_USE;
 295
 296         if (check_locality(chip, loc) >= 0)
 297                 return loc;  /* We already have the locality */
 298
 299         iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
 300
 301         /* Wait for burstcount */
 302         start = get_timer(0);
 303         stop = chip->vendor.timeout_a;
 304         do {
 305                 if (check_locality(chip, loc) >= 0)
 306                         return loc;
 307                 udelay(TPM_TIMEOUT * 1000);
 308         } while (get_timer(start) < stop);
 309
 310         return -1;
 311 }
 312
 313 static u8 tpm_tis_i2c_status(struct tpm_chip *chip)
 314 {
 315         /* NOTE: Since i2c read may fail, return 0 in this case --> time-out */
 316         u8 buf;
 317
 318         if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
 319                 return 0;
 320         else
 321                 return buf;
 322 }
 323
 324 static void tpm_tis_i2c_ready(struct tpm_chip *chip)
 325 {
 326         /* This causes the current command to be aborted */
 327         u8 buf = TPM_STS_COMMAND_READY;
 328
 329         iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1);
 330 }
 331
 332 static ssize_t get_burstcount(struct tpm_chip *chip)
 333 {
 334         unsigned long start, stop;
 335         ssize_t burstcnt;
 336         u8 addr, buf[3];
 337
 338         /* Wait for burstcount */
 339         /* XXX: Which timeout value? Spec has 2 answers (c & d) */
 340         start = get_timer(0);
 341         stop = chip->vendor.timeout_d;
 342         do {
 343                 /* Note: STS is little endian */
 344                 addr = TPM_STS(chip->vendor.locality) + 1;
 345                 if (iic_tpm_read(addr, buf, 3) < 0)
 346                         burstcnt = 0;
 347                 else
 348                         burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
 349
 350                 if (burstcnt)
 351                         return burstcnt;
 352                 udelay(TPM_TIMEOUT * 1000);
 353         } while (get_timer(start) < stop);
 354
 355         return -EBUSY;
 356 }
 357
 358 static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 359                 int *status)
 360 {
 361         unsigned long start, stop;
 362
 363         /* Check current status */
 364         *status = tpm_tis_i2c_status(chip);
 365         if ((*status & mask) == mask)
 366                 return 0;
 367
 368         start = get_timer(0);
 369         stop = timeout;
 370         do {
 371                 udelay(TPM_TIMEOUT * 1000);
 372                 *status = tpm_tis_i2c_status(chip);
 373                 if ((*status & mask) == mask)
 374                         return 0;
 375         } while (get_timer(start) < stop);
 376
 377         return -ETIME;
 378 }
 379
 380 static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 381 {
 382         size_t size = 0;
 383         ssize_t burstcnt;
 384         int rc;
 385
 386         while (size < count) {
 387                 burstcnt = get_burstcount(chip);
 388
 389                 /* burstcount < 0 -> tpm is busy */
 390                 if (burstcnt < 0)
 391                         return burstcnt;
 392
 393                 /* Limit received data to max left */
 394                 if (burstcnt > (count - size))
 395                         burstcnt = count - size;
 396
 397                 rc = iic_tpm_read(TPM_DATA_FIFO(chip->vendor.locality),
 398                                 &(buf[size]), burstcnt);
 399                 if (rc == 0)
 400                         size += burstcnt;
 401         }
 402
 403         return size;
 404 }
 405
 406 static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 407 {
 408         int size = 0;
 409         int expected, status;
 410
 411         if (count < TPM_HEADER_SIZE) {
 412                 size = -EIO;
 413                 goto out;
 414         }
 415
 416         /* Read first 10 bytes, including tag, paramsize, and result */
 417         size = recv_data(chip, buf, TPM_HEADER_SIZE);
 418         if (size < TPM_HEADER_SIZE) {
 419                 error("Unable to read header\n");
 420                 goto out;
 421         }
 422
 423         expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);
 424         if ((size_t)expected > count) {
 425                 size = -EIO;
 426                 goto out;
 427         }
 428
 429         size += recv_data(chip, &buf[TPM_HEADER_SIZE],
 430                         expected - TPM_HEADER_SIZE);
 431         if (size < expected) {
 432                 error("Unable to read remainder of result\n");
 433                 size = -ETIME;
 434                 goto out;
 435         }
 436
 437         wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
 438         if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
 439                 error("Error left over data\n");
 440                 size = -EIO;
 441                 goto out;
 442         }
 443
 444 out:
 445         tpm_tis_i2c_ready(chip);
 446         /*
 447          * The TPM needs some time to clean up here,
 448          * so we sleep rather than keeping the bus busy
 449          */
 450         udelay(2000);
 451         release_locality(chip, chip->vendor.locality, 0);
 452
 453         return size;
 454 }
 455
 456 static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
 457 {
 458         int rc, status;
 459         ssize_t burstcnt;
 460         size_t count = 0;
 461         int retry = 0;
 462         u8 sts = TPM_STS_GO;
 463
 464         if (len > TPM_DEV_BUFSIZE)
 465                 return -E2BIG;  /* Command is too long for our tpm, sorry */
 466
 467         if (request_locality(chip, 0) < 0)
 468                 return -EBUSY;
 469
 470         status = tpm_tis_i2c_status(chip);
 471         if ((status & TPM_STS_COMMAND_READY) == 0) {
 472                 tpm_tis_i2c_ready(chip);
 473                 if (wait_for_stat(chip, TPM_STS_COMMAND_READY,
 474                                   chip->vendor.timeout_b, &status) < 0) {
 475                         rc = -ETIME;
 476                         goto out_err;
 477                 }
 478         }
 479
 480         burstcnt = get_burstcount(chip);
 481
 482         /* burstcount < 0 -> tpm is busy */
 483         if (burstcnt < 0)
 484                 return burstcnt;
 485
 486         while (count < len - 1) {
 487                 if (burstcnt > len - 1 - count)
 488                         burstcnt = len - 1 - count;
 489
 490 #ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION
 491                 if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION)
 492                         burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION;
 493 #endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */
 494
 495                 rc = iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality),
 496                                 &(buf[count]), burstcnt);
 497                 if (rc == 0)
 498                         count += burstcnt;
 499                 else {
 500                         retry++;
 501                         wait_for_stat(chip, TPM_STS_VALID,
 502                                       chip->vendor.timeout_c, &status);
 503
 504                         if ((status & TPM_STS_DATA_EXPECT) == 0) {
 505                                 rc = -EIO;
 506                                 goto out_err;
 507                         }
 508                 }
 509         }
 510
 511         /* Write last byte */
 512         iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1);
 513         wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
 514         if ((status & TPM_STS_DATA_EXPECT) != 0) {
 515                 rc = -EIO;
 516                 goto out_err;
 517         }
 518
 519         /* Go and do it */
 520         iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1);
 521
 522         return len;
 523
 524 out_err:
 525         tpm_tis_i2c_ready(chip);
 526         /*
 527          * The TPM needs some time to clean up here,
 528          * so we sleep rather than keeping the bus busy
 529          */
 530         udelay(2000);
 531         release_locality(chip, chip->vendor.locality, 0);
 532
 533         return rc;
 534 }
 535
 536 static struct tpm_vendor_specific tpm_tis_i2c = {
 537         .status = tpm_tis_i2c_status,
 538         .recv = tpm_tis_i2c_recv,
 539         .send = tpm_tis_i2c_send,
 540         .cancel = tpm_tis_i2c_ready,
 541         .req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 542         .req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 543         .req_canceled = TPM_STS_COMMAND_READY,
 544 };
 545
 546
 547 static enum i2c_chip_type tpm_vendor_chip_type(void)
 548 {
 549 #ifdef CONFIG_OF_CONTROL
 550         const void *blob = gd->fdt_blob;
 551
 552         if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9645_TPM) >= 0)
 553                 return SLB9645;
 554
 555         if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM) >= 0)
 556                 return SLB9635;
 557 #endif
 558         return UNKNOWN;
 559 }
 560
 561 /* Initialisation of i2c tpm */
 562 int tpm_vendor_init(uint32_t dev_addr)
 563 {
 564         u32 vendor;
 565         u32 expected_did_vid;
 566         uint old_addr;
 567         int rc = 0;
 568         struct tpm_chip *chip;
 569
 570         old_addr = tpm_dev.addr;
 571         if (dev_addr != 0)
 572                 tpm_dev.addr = dev_addr;
 573
 574         tpm_dev.chip_type = tpm_vendor_chip_type();
 575
 576         chip = tpm_register_hardware(&tpm_tis_i2c);
 577         if (chip < 0) {
 578                 rc = -ENODEV;
 579                 goto out_err;
 580         }
 581
 582         /* Disable interrupts (not supported) */
 583         chip->vendor.irq = 0;
 584
 585         /* Default timeouts */
 586         chip->vendor.timeout_a = TIS_SHORT_TIMEOUT;
 587         chip->vendor.timeout_b = TIS_LONG_TIMEOUT;
 588         chip->vendor.timeout_c = TIS_SHORT_TIMEOUT;
 589         chip->vendor.timeout_d = TIS_SHORT_TIMEOUT;
 590
 591         if (request_locality(chip, 0) < 0) {
 592                 rc = -ENODEV;
 593                 goto out_err;
 594         }
 595
 596         /* Read four bytes from DID_VID register */
 597         if (iic_tpm_read(TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
 598                 rc = -EIO;
 599                 goto out_release;
 600         }
 601
 602         if (tpm_dev.chip_type == SLB9635) {
 603                 vendor = be32_to_cpu(vendor);
 604                 expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
 605         } else {
 606                 /* device id and byte order has changed for newer i2c tpms */
 607                 expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
 608         }
 609
 610         if (tpm_dev.chip_type != UNKNOWN && vendor != expected_did_vid) {
 611                 error("Vendor id did not match! ID was %08x\n", vendor);
 612                 rc = -ENODEV;
 613                 goto out_release;
 614         }
 615
 616         debug("1.2 TPM (chip type %s device-id 0x%X)\n",
 617               chip_name[tpm_dev.chip_type], vendor >> 16);
 618
 619         /*
 620          * A timeout query to TPM can be placed here.
 621          * Standard timeout values are used so far
 622          */
 623
 624         return 0;
 625
 626 out_release:
 627         release_locality(chip, 0, 1);
 628
 629 out_err:
 630         tpm_dev.addr = old_addr;
 631         return rc;
 632 }
 633
 634 void tpm_vendor_cleanup(struct tpm_chip *chip)
 635 {
 636         release_locality(chip, chip->vendor.locality, 1);
 637 }