root/drivers/char/tpm/st33zp24/st33zp24.c

DEFINITIONS

1. clear_interruption
2. st33zp24_cancel
3. st33zp24_status
4. check_locality
5. request_locality
6. release_locality
7. get_burstcount
8. wait_for_tpm_stat_cond
9. wait_for_stat
10. recv_data
11. tpm_ioserirq_handler
12. st33zp24_send
13. st33zp24_recv
14. st33zp24_req_canceled
15. st33zp24_probe
16. st33zp24_remove
17. st33zp24_pm_suspend
18. st33zp24_pm_resume

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * STMicroelectronics TPM Linux driver for TPM ST33ZP24
   4  * Copyright (C) 2009 - 2016 STMicroelectronics
   5  */
   6 
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/kernel.h>
  10 #include <linux/delay.h>
  11 #include <linux/wait.h>
  12 #include <linux/freezer.h>
  13 #include <linux/string.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/gpio.h>
  16 #include <linux/sched.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/io.h>
  19 #include <linux/slab.h>
  20 
  21 #include "../tpm.h"
  22 #include "st33zp24.h"
  23 
  24 #define TPM_ACCESS                      0x0
  25 #define TPM_STS                         0x18
  26 #define TPM_DATA_FIFO                   0x24
  27 #define TPM_INTF_CAPABILITY             0x14
  28 #define TPM_INT_STATUS                  0x10
  29 #define TPM_INT_ENABLE                  0x08
  30 
  31 #define LOCALITY0                       0
  32 
  33 enum st33zp24_access {
  34         TPM_ACCESS_VALID = 0x80,
  35         TPM_ACCESS_ACTIVE_LOCALITY = 0x20,
  36         TPM_ACCESS_REQUEST_PENDING = 0x04,
  37         TPM_ACCESS_REQUEST_USE = 0x02,
  38 };
  39 
  40 enum st33zp24_status {
  41         TPM_STS_VALID = 0x80,
  42         TPM_STS_COMMAND_READY = 0x40,
  43         TPM_STS_GO = 0x20,
  44         TPM_STS_DATA_AVAIL = 0x10,
  45         TPM_STS_DATA_EXPECT = 0x08,
  46 };
  47 
  48 enum st33zp24_int_flags {
  49         TPM_GLOBAL_INT_ENABLE = 0x80,
  50         TPM_INTF_CMD_READY_INT = 0x080,
  51         TPM_INTF_FIFO_AVALAIBLE_INT = 0x040,
  52         TPM_INTF_WAKE_UP_READY_INT = 0x020,
  53         TPM_INTF_LOCALITY_CHANGE_INT = 0x004,
  54         TPM_INTF_STS_VALID_INT = 0x002,
  55         TPM_INTF_DATA_AVAIL_INT = 0x001,
  56 };
  57 
  58 enum tis_defaults {
  59         TIS_SHORT_TIMEOUT = 750,
  60         TIS_LONG_TIMEOUT = 2000,
  61 };
  62 
  63 /*
  64  * clear_interruption clear the pending interrupt.
  65  * @param: tpm_dev, the tpm device device.
  66  * @return: the interrupt status value.
  67  */
  68 static u8 clear_interruption(struct st33zp24_dev *tpm_dev)
  69 {
  70         u8 interrupt;
  71 
  72         tpm_dev->ops->recv(tpm_dev->phy_id, TPM_INT_STATUS, &interrupt, 1);
  73         tpm_dev->ops->send(tpm_dev->phy_id, TPM_INT_STATUS, &interrupt, 1);
  74         return interrupt;
  75 } /* clear_interruption() */
  76 
  77 /*
  78  * st33zp24_cancel, cancel the current command execution or
  79  * set STS to COMMAND READY.
  80  * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h
  81  */
  82 static void st33zp24_cancel(struct tpm_chip *chip)
  83 {
  84         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
  85         u8 data;
  86 
  87         data = TPM_STS_COMMAND_READY;
  88         tpm_dev->ops->send(tpm_dev->phy_id, TPM_STS, &data, 1);
  89 } /* st33zp24_cancel() */
  90 
  91 /*
  92  * st33zp24_status return the TPM_STS register
  93  * @param: chip, the tpm chip description
  94  * @return: the TPM_STS register value.
  95  */
  96 static u8 st33zp24_status(struct tpm_chip *chip)
  97 {
  98         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
  99         u8 data;
 100 
 101         tpm_dev->ops->recv(tpm_dev->phy_id, TPM_STS, &data, 1);
 102         return data;
 103 } /* st33zp24_status() */
 104 
 105 /*
 106  * check_locality if the locality is active
 107  * @param: chip, the tpm chip description
 108  * @return: true if LOCALITY0 is active, otherwise false
 109  */
 110 static bool check_locality(struct tpm_chip *chip)
 111 {
 112         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 113         u8 data;
 114         u8 status;
 115 
 116         status = tpm_dev->ops->recv(tpm_dev->phy_id, TPM_ACCESS, &data, 1);
 117         if (status && (data &
 118                 (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
 119                 (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
 120                 return true;
 121 
 122         return false;
 123 } /* check_locality() */
 124 
 125 /*
 126  * request_locality request the TPM locality
 127  * @param: chip, the chip description
 128  * @return: the active locality or negative value.
 129  */
 130 static int request_locality(struct tpm_chip *chip)
 131 {
 132         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 133         unsigned long stop;
 134         long ret;
 135         u8 data;
 136 
 137         if (check_locality(chip))
 138                 return tpm_dev->locality;
 139 
 140         data = TPM_ACCESS_REQUEST_USE;
 141         ret = tpm_dev->ops->send(tpm_dev->phy_id, TPM_ACCESS, &data, 1);
 142         if (ret < 0)
 143                 return ret;
 144 
 145         stop = jiffies + chip->timeout_a;
 146 
 147         /* Request locality is usually effective after the request */
 148         do {
 149                 if (check_locality(chip))
 150                         return tpm_dev->locality;
 151                 msleep(TPM_TIMEOUT);
 152         } while (time_before(jiffies, stop));
 153 
 154         /* could not get locality */
 155         return -EACCES;
 156 } /* request_locality() */
 157 
 158 /*
 159  * release_locality release the active locality
 160  * @param: chip, the tpm chip description.
 161  */
 162 static void release_locality(struct tpm_chip *chip)
 163 {
 164         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 165         u8 data;
 166 
 167         data = TPM_ACCESS_ACTIVE_LOCALITY;
 168 
 169         tpm_dev->ops->send(tpm_dev->phy_id, TPM_ACCESS, &data, 1);
 170 }
 171 
 172 /*
 173  * get_burstcount return the burstcount value
 174  * @param: chip, the chip description
 175  * return: the burstcount or negative value.
 176  */
 177 static int get_burstcount(struct tpm_chip *chip)
 178 {
 179         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 180         unsigned long stop;
 181         int burstcnt, status;
 182         u8 temp;
 183 
 184         stop = jiffies + chip->timeout_d;
 185         do {
 186                 status = tpm_dev->ops->recv(tpm_dev->phy_id, TPM_STS + 1,
 187                                             &temp, 1);
 188                 if (status < 0)
 189                         return -EBUSY;
 190 
 191                 burstcnt = temp;
 192                 status = tpm_dev->ops->recv(tpm_dev->phy_id, TPM_STS + 2,
 193                                             &temp, 1);
 194                 if (status < 0)
 195                         return -EBUSY;
 196 
 197                 burstcnt |= temp << 8;
 198                 if (burstcnt)
 199                         return burstcnt;
 200                 msleep(TPM_TIMEOUT);
 201         } while (time_before(jiffies, stop));
 202         return -EBUSY;
 203 } /* get_burstcount() */
 204 
 205 
 206 /*
 207  * wait_for_tpm_stat_cond
 208  * @param: chip, chip description
 209  * @param: mask, expected mask value
 210  * @param: check_cancel, does the command expected to be canceled ?
 211  * @param: canceled, did we received a cancel request ?
 212  * @return: true if status == mask or if the command is canceled.
 213  * false in other cases.
 214  */
 215 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
 216                                 bool check_cancel, bool *canceled)
 217 {
 218         u8 status = chip->ops->status(chip);
 219 
 220         *canceled = false;
 221         if ((status & mask) == mask)
 222                 return true;
 223         if (check_cancel && chip->ops->req_canceled(chip, status)) {
 224                 *canceled = true;
 225                 return true;
 226         }
 227         return false;
 228 }
 229 
 230 /*
 231  * wait_for_stat wait for a TPM_STS value
 232  * @param: chip, the tpm chip description
 233  * @param: mask, the value mask to wait
 234  * @param: timeout, the timeout
 235  * @param: queue, the wait queue.
 236  * @param: check_cancel, does the command can be cancelled ?
 237  * @return: the tpm status, 0 if success, -ETIME if timeout is reached.
 238  */
 239 static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 240                         wait_queue_head_t *queue, bool check_cancel)
 241 {
 242         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 243         unsigned long stop;
 244         int ret = 0;
 245         bool canceled = false;
 246         bool condition;
 247         u32 cur_intrs;
 248         u8 status;
 249 
 250         /* check current status */
 251         status = st33zp24_status(chip);
 252         if ((status & mask) == mask)
 253                 return 0;
 254 
 255         stop = jiffies + timeout;
 256 
 257         if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 258                 cur_intrs = tpm_dev->intrs;
 259                 clear_interruption(tpm_dev);
 260                 enable_irq(tpm_dev->irq);
 261 
 262                 do {
 263                         if (ret == -ERESTARTSYS && freezing(current))
 264                                 clear_thread_flag(TIF_SIGPENDING);
 265 
 266                         timeout = stop - jiffies;
 267                         if ((long) timeout <= 0)
 268                                 return -1;
 269 
 270                         ret = wait_event_interruptible_timeout(*queue,
 271                                                 cur_intrs != tpm_dev->intrs,
 272                                                 timeout);
 273                         clear_interruption(tpm_dev);
 274                         condition = wait_for_tpm_stat_cond(chip, mask,
 275                                                 check_cancel, &canceled);
 276                         if (ret >= 0 && condition) {
 277                                 if (canceled)
 278                                         return -ECANCELED;
 279                                 return 0;
 280                         }
 281                 } while (ret == -ERESTARTSYS && freezing(current));
 282 
 283                 disable_irq_nosync(tpm_dev->irq);
 284 
 285         } else {
 286                 do {
 287                         msleep(TPM_TIMEOUT);
 288                         status = chip->ops->status(chip);
 289                         if ((status & mask) == mask)
 290                                 return 0;
 291                 } while (time_before(jiffies, stop));
 292         }
 293 
 294         return -ETIME;
 295 } /* wait_for_stat() */
 296 
 297 /*
 298  * recv_data receive data
 299  * @param: chip, the tpm chip description
 300  * @param: buf, the buffer where the data are received
 301  * @param: count, the number of data to receive
 302  * @return: the number of bytes read from TPM FIFO.
 303  */
 304 static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 305 {
 306         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 307         int size = 0, burstcnt, len, ret;
 308 
 309         while (size < count &&
 310                wait_for_stat(chip,
 311                              TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 312                              chip->timeout_c,
 313                              &tpm_dev->read_queue, true) == 0) {
 314                 burstcnt = get_burstcount(chip);
 315                 if (burstcnt < 0)
 316                         return burstcnt;
 317                 len = min_t(int, burstcnt, count - size);
 318                 ret = tpm_dev->ops->recv(tpm_dev->phy_id, TPM_DATA_FIFO,
 319                                          buf + size, len);
 320                 if (ret < 0)
 321                         return ret;
 322 
 323                 size += len;
 324         }
 325         return size;
 326 }
 327 
 328 /*
 329  * tpm_ioserirq_handler the serirq irq handler
 330  * @param: irq, the tpm chip description
 331  * @param: dev_id, the description of the chip
 332  * @return: the status of the handler.
 333  */
 334 static irqreturn_t tpm_ioserirq_handler(int irq, void *dev_id)
 335 {
 336         struct tpm_chip *chip = dev_id;
 337         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 338 
 339         tpm_dev->intrs++;
 340         wake_up_interruptible(&tpm_dev->read_queue);
 341         disable_irq_nosync(tpm_dev->irq);
 342 
 343         return IRQ_HANDLED;
 344 } /* tpm_ioserirq_handler() */
 345 
 346 /*
 347  * st33zp24_send send TPM commands through the I2C bus.
 348  *
 349  * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h
 350  * @param: buf, the buffer to send.
 351  * @param: count, the number of bytes to send.
 352  * @return: In case of success the number of bytes sent.
 353  *                      In other case, a < 0 value describing the issue.
 354  */
 355 static int st33zp24_send(struct tpm_chip *chip, unsigned char *buf,
 356                          size_t len)
 357 {
 358         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 359         u32 status, i, size, ordinal;
 360         int burstcnt = 0;
 361         int ret;
 362         u8 data;
 363 
 364         if (len < TPM_HEADER_SIZE)
 365                 return -EBUSY;
 366 
 367         ret = request_locality(chip);
 368         if (ret < 0)
 369                 return ret;
 370 
 371         status = st33zp24_status(chip);
 372         if ((status & TPM_STS_COMMAND_READY) == 0) {
 373                 st33zp24_cancel(chip);
 374                 if (wait_for_stat
 375                     (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
 376                      &tpm_dev->read_queue, false) < 0) {
 377                         ret = -ETIME;
 378                         goto out_err;
 379                 }
 380         }
 381 
 382         for (i = 0; i < len - 1;) {
 383                 burstcnt = get_burstcount(chip);
 384                 if (burstcnt < 0)
 385                         return burstcnt;
 386                 size = min_t(int, len - i - 1, burstcnt);
 387                 ret = tpm_dev->ops->send(tpm_dev->phy_id, TPM_DATA_FIFO,
 388                                          buf + i, size);
 389                 if (ret < 0)
 390                         goto out_err;
 391 
 392                 i += size;
 393         }
 394 
 395         status = st33zp24_status(chip);
 396         if ((status & TPM_STS_DATA_EXPECT) == 0) {
 397                 ret = -EIO;
 398                 goto out_err;
 399         }
 400 
 401         ret = tpm_dev->ops->send(tpm_dev->phy_id, TPM_DATA_FIFO,
 402                                  buf + len - 1, 1);
 403         if (ret < 0)
 404                 goto out_err;
 405 
 406         status = st33zp24_status(chip);
 407         if ((status & TPM_STS_DATA_EXPECT) != 0) {
 408                 ret = -EIO;
 409                 goto out_err;
 410         }
 411 
 412         data = TPM_STS_GO;
 413         ret = tpm_dev->ops->send(tpm_dev->phy_id, TPM_STS, &data, 1);
 414         if (ret < 0)
 415                 goto out_err;
 416 
 417         if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 418                 ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
 419 
 420                 ret = wait_for_stat(chip, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 421                                 tpm_calc_ordinal_duration(chip, ordinal),
 422                                 &tpm_dev->read_queue, false);
 423                 if (ret < 0)
 424                         goto out_err;
 425         }
 426 
 427         return 0;
 428 out_err:
 429         st33zp24_cancel(chip);
 430         release_locality(chip);
 431         return ret;
 432 }
 433 
 434 /*
 435  * st33zp24_recv received TPM response through TPM phy.
 436  * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h.
 437  * @param: buf, the buffer to store datas.
 438  * @param: count, the number of bytes to send.
 439  * @return: In case of success the number of bytes received.
 440  *          In other case, a < 0 value describing the issue.
 441  */
 442 static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
 443                             size_t count)
 444 {
 445         int size = 0;
 446         u32 expected;
 447 
 448         if (!chip)
 449                 return -EBUSY;
 450 
 451         if (count < TPM_HEADER_SIZE) {
 452                 size = -EIO;
 453                 goto out;
 454         }
 455 
 456         size = recv_data(chip, buf, TPM_HEADER_SIZE);
 457         if (size < TPM_HEADER_SIZE) {
 458                 dev_err(&chip->dev, "Unable to read header\n");
 459                 goto out;
 460         }
 461 
 462         expected = be32_to_cpu(*(__be32 *)(buf + 2));
 463         if (expected > count || expected < TPM_HEADER_SIZE) {
 464                 size = -EIO;
 465                 goto out;
 466         }
 467 
 468         size += recv_data(chip, &buf[TPM_HEADER_SIZE],
 469                         expected - TPM_HEADER_SIZE);
 470         if (size < expected) {
 471                 dev_err(&chip->dev, "Unable to read remainder of result\n");
 472                 size = -ETIME;
 473         }
 474 
 475 out:
 476         st33zp24_cancel(chip);
 477         release_locality(chip);
 478         return size;
 479 }
 480 
 481 /*
 482  * st33zp24_req_canceled
 483  * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h.
 484  * @param: status, the TPM status.
 485  * @return: Does TPM ready to compute a new command ? true.
 486  */
 487 static bool st33zp24_req_canceled(struct tpm_chip *chip, u8 status)
 488 {
 489         return (status == TPM_STS_COMMAND_READY);
 490 }
 491 
 492 static const struct tpm_class_ops st33zp24_tpm = {
 493         .flags = TPM_OPS_AUTO_STARTUP,
 494         .send = st33zp24_send,
 495         .recv = st33zp24_recv,
 496         .cancel = st33zp24_cancel,
 497         .status = st33zp24_status,
 498         .req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 499         .req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 500         .req_canceled = st33zp24_req_canceled,
 501 };
 502 
 503 /*
 504  * st33zp24_probe initialize the TPM device
 505  * @param: client, the i2c_client drescription (TPM I2C description).
 506  * @param: id, the i2c_device_id struct.
 507  * @return: 0 in case of success.
 508  *       -1 in other case.
 509  */
 510 int st33zp24_probe(void *phy_id, const struct st33zp24_phy_ops *ops,
 511                    struct device *dev, int irq, int io_lpcpd)
 512 {
 513         int ret;
 514         u8 intmask = 0;
 515         struct tpm_chip *chip;
 516         struct st33zp24_dev *tpm_dev;
 517 
 518         chip = tpmm_chip_alloc(dev, &st33zp24_tpm);
 519         if (IS_ERR(chip))
 520                 return PTR_ERR(chip);
 521 
 522         tpm_dev = devm_kzalloc(dev, sizeof(struct st33zp24_dev),
 523                                GFP_KERNEL);
 524         if (!tpm_dev)
 525                 return -ENOMEM;
 526 
 527         tpm_dev->phy_id = phy_id;
 528         tpm_dev->ops = ops;
 529         dev_set_drvdata(&chip->dev, tpm_dev);
 530 
 531         chip->timeout_a = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
 532         chip->timeout_b = msecs_to_jiffies(TIS_LONG_TIMEOUT);
 533         chip->timeout_c = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
 534         chip->timeout_d = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
 535 
 536         tpm_dev->locality = LOCALITY0;
 537 
 538         if (irq) {
 539                 /* INTERRUPT Setup */
 540                 init_waitqueue_head(&tpm_dev->read_queue);
 541                 tpm_dev->intrs = 0;
 542 
 543                 if (request_locality(chip) != LOCALITY0) {
 544                         ret = -ENODEV;
 545                         goto _tpm_clean_answer;
 546                 }
 547 
 548                 clear_interruption(tpm_dev);
 549                 ret = devm_request_irq(dev, irq, tpm_ioserirq_handler,
 550                                 IRQF_TRIGGER_HIGH, "TPM SERIRQ management",
 551                                 chip);
 552                 if (ret < 0) {
 553                         dev_err(&chip->dev, "TPM SERIRQ signals %d not available\n",
 554                                 irq);
 555                         goto _tpm_clean_answer;
 556                 }
 557 
 558                 intmask |= TPM_INTF_CMD_READY_INT
 559                         |  TPM_INTF_STS_VALID_INT
 560                         |  TPM_INTF_DATA_AVAIL_INT;
 561 
 562                 ret = tpm_dev->ops->send(tpm_dev->phy_id, TPM_INT_ENABLE,
 563                                          &intmask, 1);
 564                 if (ret < 0)
 565                         goto _tpm_clean_answer;
 566 
 567                 intmask = TPM_GLOBAL_INT_ENABLE;
 568                 ret = tpm_dev->ops->send(tpm_dev->phy_id, (TPM_INT_ENABLE + 3),
 569                                          &intmask, 1);
 570                 if (ret < 0)
 571                         goto _tpm_clean_answer;
 572 
 573                 tpm_dev->irq = irq;
 574                 chip->flags |= TPM_CHIP_FLAG_IRQ;
 575 
 576                 disable_irq_nosync(tpm_dev->irq);
 577         }
 578 
 579         return tpm_chip_register(chip);
 580 _tpm_clean_answer:
 581         dev_info(&chip->dev, "TPM initialization fail\n");
 582         return ret;
 583 }
 584 EXPORT_SYMBOL(st33zp24_probe);
 585 
 586 /*
 587  * st33zp24_remove remove the TPM device
 588  * @param: tpm_data, the tpm phy.
 589  * @return: 0 in case of success.
 590  */
 591 int st33zp24_remove(struct tpm_chip *chip)
 592 {
 593         tpm_chip_unregister(chip);
 594         return 0;
 595 }
 596 EXPORT_SYMBOL(st33zp24_remove);
 597 
 598 #ifdef CONFIG_PM_SLEEP
 599 /*
 600  * st33zp24_pm_suspend suspend the TPM device
 601  * @param: tpm_data, the tpm phy.
 602  * @param: mesg, the power management message.
 603  * @return: 0 in case of success.
 604  */
 605 int st33zp24_pm_suspend(struct device *dev)
 606 {
 607         struct tpm_chip *chip = dev_get_drvdata(dev);
 608         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 609 
 610         int ret = 0;
 611 
 612         if (gpio_is_valid(tpm_dev->io_lpcpd))
 613                 gpio_set_value(tpm_dev->io_lpcpd, 0);
 614         else
 615                 ret = tpm_pm_suspend(dev);
 616 
 617         return ret;
 618 } /* st33zp24_pm_suspend() */
 619 EXPORT_SYMBOL(st33zp24_pm_suspend);
 620 
 621 /*
 622  * st33zp24_pm_resume resume the TPM device
 623  * @param: tpm_data, the tpm phy.
 624  * @return: 0 in case of success.
 625  */
 626 int st33zp24_pm_resume(struct device *dev)
 627 {
 628         struct tpm_chip *chip = dev_get_drvdata(dev);
 629         struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 630         int ret = 0;
 631 
 632         if (gpio_is_valid(tpm_dev->io_lpcpd)) {
 633                 gpio_set_value(tpm_dev->io_lpcpd, 1);
 634                 ret = wait_for_stat(chip,
 635                                 TPM_STS_VALID, chip->timeout_b,
 636                                 &tpm_dev->read_queue, false);
 637         } else {
 638                 ret = tpm_pm_resume(dev);
 639                 if (!ret)
 640                         tpm1_do_selftest(chip);
 641         }
 642         return ret;
 643 } /* st33zp24_pm_resume() */
 644 EXPORT_SYMBOL(st33zp24_pm_resume);
 645 #endif
 646 
 647 MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
 648 MODULE_DESCRIPTION("ST33ZP24 TPM 1.2 driver");
 649 MODULE_VERSION("1.3.0");
 650 MODULE_LICENSE("GPL");