drivers/char/tpm/tpm_i2c_nuvoton.c

   1 /******************************************************************************
   2  * Nuvoton TPM I2C Device Driver Interface for WPCT301/NPCT501,
   3  * based on the TCG TPM Interface Spec version 1.2.
   4  * Specifications at www.trustedcomputinggroup.org
   5  *
   6  * Copyright (C) 2011, Nuvoton Technology Corporation.
   7  *  Dan Morav <[email protected]>
   8  * Copyright (C) 2013, Obsidian Research Corp.
   9  *  Jason Gunthorpe <[email protected]>
  10  *
  11  * This program is free software: you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation, either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program.  If not, see http://www.gnu.org/licenses/>.
  23  *
  24  * Nuvoton contact information: [email protected]
  25  *****************************************************************************/
  26
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/slab.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/wait.h>
  33 #include <linux/i2c.h>
  34 #include "tpm.h"
  35
  36 /* I2C interface offsets */
  37 #define TPM_STS                0x00
  38 #define TPM_BURST_COUNT        0x01
  39 #define TPM_DATA_FIFO_W        0x20
  40 #define TPM_DATA_FIFO_R        0x40
  41 #define TPM_VID_DID_RID        0x60
  42 /* TPM command header size */
  43 #define TPM_HEADER_SIZE        10
  44 #define TPM_RETRY      5
  45 /*
  46  * I2C bus device maximum buffer size w/o counting I2C address or command
  47  * i.e. max size required for I2C write is 34 = addr, command, 32 bytes data
  48  */
  49 #define TPM_I2C_MAX_BUF_SIZE           32
  50 #define TPM_I2C_RETRY_COUNT            32
  51 #define TPM_I2C_BUS_DELAY              1       /* msec */
  52 #define TPM_I2C_RETRY_DELAY_SHORT      2       /* msec */
  53 #define TPM_I2C_RETRY_DELAY_LONG       10      /* msec */
  54
  55 #define I2C_DRIVER_NAME "tpm_i2c_nuvoton"
  56
  57 struct priv_data {
  58         unsigned int intrs;
  59 };
  60
  61 static s32 i2c_nuvoton_read_buf(struct i2c_client *client, u8 offset, u8 size,
  62                                 u8 *data)
  63 {
  64         s32 status;
  65
  66         status = i2c_smbus_read_i2c_block_data(client, offset, size, data);
  67         dev_dbg(&client->dev,
  68                 "%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
  69                 offset, size, (int)size, data, status);
  70         return status;
  71 }
  72
  73 static s32 i2c_nuvoton_write_buf(struct i2c_client *client, u8 offset, u8 size,
  74                                  u8 *data)
  75 {
  76         s32 status;
  77
  78         status = i2c_smbus_write_i2c_block_data(client, offset, size, data);
  79         dev_dbg(&client->dev,
  80                 "%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
  81                 offset, size, (int)size, data, status);
  82         return status;
  83 }
  84
  85 #define TPM_STS_VALID          0x80
  86 #define TPM_STS_COMMAND_READY  0x40
  87 #define TPM_STS_GO             0x20
  88 #define TPM_STS_DATA_AVAIL     0x10
  89 #define TPM_STS_EXPECT         0x08
  90 #define TPM_STS_RESPONSE_RETRY 0x02
  91 #define TPM_STS_ERR_VAL        0x07    /* bit2...bit0 reads always 0 */
  92
  93 #define TPM_I2C_SHORT_TIMEOUT  750     /* ms */
  94 #define TPM_I2C_LONG_TIMEOUT   2000    /* 2 sec */
  95
  96 /* read TPM_STS register */
  97 static u8 i2c_nuvoton_read_status(struct tpm_chip *chip)
  98 {
  99         struct i2c_client *client = to_i2c_client(chip->pdev);
 100         s32 status;
 101         u8 data;
 102
 103         status = i2c_nuvoton_read_buf(client, TPM_STS, 1, &data);
 104         if (status <= 0) {
 105                 dev_err(chip->pdev, "%s() error return %d\n", __func__,
 106                         status);
 107                 data = TPM_STS_ERR_VAL;
 108         }
 109
 110         return data;
 111 }
 112
 113 /* write byte to TPM_STS register */
 114 static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
 115 {
 116         s32 status;
 117         int i;
 118
 119         /* this causes the current command to be aborted */
 120         for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
 121                 status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
 122                 msleep(TPM_I2C_BUS_DELAY);
 123         }
 124         return status;
 125 }
 126
 127 /* write commandReady to TPM_STS register */
 128 static void i2c_nuvoton_ready(struct tpm_chip *chip)
 129 {
 130         struct i2c_client *client = to_i2c_client(chip->pdev);
 131         s32 status;
 132
 133         /* this causes the current command to be aborted */
 134         status = i2c_nuvoton_write_status(client, TPM_STS_COMMAND_READY);
 135         if (status < 0)
 136                 dev_err(chip->pdev,
 137                         "%s() fail to write TPM_STS.commandReady\n", __func__);
 138 }
 139
 140 /* read burstCount field from TPM_STS register
 141  * return -1 on fail to read */
 142 static int i2c_nuvoton_get_burstcount(struct i2c_client *client,
 143                                       struct tpm_chip *chip)
 144 {
 145         unsigned long stop = jiffies + chip->vendor.timeout_d;
 146         s32 status;
 147         int burst_count = -1;
 148         u8 data;
 149
 150         /* wait for burstcount to be non-zero */
 151         do {
 152                 /* in I2C burstCount is 1 byte */
 153                 status = i2c_nuvoton_read_buf(client, TPM_BURST_COUNT, 1,
 154                                               &data);
 155                 if (status > 0 && data > 0) {
 156                         burst_count = min_t(u8, TPM_I2C_MAX_BUF_SIZE, data);
 157                         break;
 158                 }
 159                 msleep(TPM_I2C_BUS_DELAY);
 160         } while (time_before(jiffies, stop));
 161
 162         return burst_count;
 163 }
 164
 165 /*
 166  * WPCT301/NPCT501 SINT# supports only dataAvail
 167  * any call to this function which is not waiting for dataAvail will
 168  * set queue to NULL to avoid waiting for interrupt
 169  */
 170 static bool i2c_nuvoton_check_status(struct tpm_chip *chip, u8 mask, u8 value)
 171 {
 172         u8 status = i2c_nuvoton_read_status(chip);
 173         return (status != TPM_STS_ERR_VAL) && ((status & mask) == value);
 174 }
 175
 176 static int i2c_nuvoton_wait_for_stat(struct tpm_chip *chip, u8 mask, u8 value,
 177                                      u32 timeout, wait_queue_head_t *queue)
 178 {
 179         if (chip->vendor.irq && queue) {
 180                 s32 rc;
 181                 struct priv_data *priv = chip->vendor.priv;
 182                 unsigned int cur_intrs = priv->intrs;
 183
 184                 enable_irq(chip->vendor.irq);
 185                 rc = wait_event_interruptible_timeout(*queue,
 186                                                       cur_intrs != priv->intrs,
 187                                                       timeout);
 188                 if (rc > 0)
 189                         return 0;
 190                 /* At this point we know that the SINT pin is asserted, so we
 191                  * do not need to do i2c_nuvoton_check_status */
 192         } else {
 193                 unsigned long ten_msec, stop;
 194                 bool status_valid;
 195
 196                 /* check current status */
 197                 status_valid = i2c_nuvoton_check_status(chip, mask, value);
 198                 if (status_valid)
 199                         return 0;
 200
 201                 /* use polling to wait for the event */
 202                 ten_msec = jiffies + msecs_to_jiffies(TPM_I2C_RETRY_DELAY_LONG);
 203                 stop = jiffies + timeout;
 204                 do {
 205                         if (time_before(jiffies, ten_msec))
 206                                 msleep(TPM_I2C_RETRY_DELAY_SHORT);
 207                         else
 208                                 msleep(TPM_I2C_RETRY_DELAY_LONG);
 209                         status_valid = i2c_nuvoton_check_status(chip, mask,
 210                                                                 value);
 211                         if (status_valid)
 212                                 return 0;
 213                 } while (time_before(jiffies, stop));
 214         }
 215         dev_err(chip->pdev, "%s(%02x, %02x) -> timeout\n", __func__, mask,
 216                 value);
 217         return -ETIMEDOUT;
 218 }
 219
 220 /* wait for dataAvail field to be set in the TPM_STS register */
 221 static int i2c_nuvoton_wait_for_data_avail(struct tpm_chip *chip, u32 timeout,
 222                                            wait_queue_head_t *queue)
 223 {
 224         return i2c_nuvoton_wait_for_stat(chip,
 225                                          TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 226                                          TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 227                                          timeout, queue);
 228 }
 229
 230 /* Read @count bytes into @buf from TPM_RD_FIFO register */
 231 static int i2c_nuvoton_recv_data(struct i2c_client *client,
 232                                  struct tpm_chip *chip, u8 *buf, size_t count)
 233 {
 234         s32 rc;
 235         int burst_count, bytes2read, size = 0;
 236
 237         while (size < count &&
 238                i2c_nuvoton_wait_for_data_avail(chip,
 239                                                chip->vendor.timeout_c,
 240                                                &chip->vendor.read_queue) == 0) {
 241                 burst_count = i2c_nuvoton_get_burstcount(client, chip);
 242                 if (burst_count < 0) {
 243                         dev_err(chip->pdev,
 244                                 "%s() fail to read burstCount=%d\n", __func__,
 245                                 burst_count);
 246                         return -EIO;
 247                 }
 248                 bytes2read = min_t(size_t, burst_count, count - size);
 249                 rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_R,
 250                                           bytes2read, &buf[size]);
 251                 if (rc < 0) {
 252                         dev_err(chip->pdev,
 253                                 "%s() fail on i2c_nuvoton_read_buf()=%d\n",
 254                                 __func__, rc);
 255                         return -EIO;
 256                 }
 257                 dev_dbg(chip->pdev, "%s(%d):", __func__, bytes2read);
 258                 size += bytes2read;
 259         }
 260
 261         return size;
 262 }
 263
 264 /* Read TPM command results */
 265 static int i2c_nuvoton_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 266 {
 267         struct device *dev = chip->pdev;
 268         struct i2c_client *client = to_i2c_client(dev);
 269         s32 rc;
 270         int expected, status, burst_count, retries, size = 0;
 271
 272         if (count < TPM_HEADER_SIZE) {
 273                 i2c_nuvoton_ready(chip);    /* return to idle */
 274                 dev_err(dev, "%s() count < header size\n", __func__);
 275                 return -EIO;
 276         }
 277         for (retries = 0; retries < TPM_RETRY; retries++) {
 278                 if (retries > 0) {
 279                         /* if this is not the first trial, set responseRetry */
 280                         i2c_nuvoton_write_status(client,
 281                                                  TPM_STS_RESPONSE_RETRY);
 282                 }
 283                 /*
 284                  * read first available (> 10 bytes), including:
 285                  * tag, paramsize, and result
 286                  */
 287                 status = i2c_nuvoton_wait_for_data_avail(
 288                         chip, chip->vendor.timeout_c, &chip->vendor.read_queue);
 289                 if (status != 0) {
 290                         dev_err(dev, "%s() timeout on dataAvail\n", __func__);
 291                         size = -ETIMEDOUT;
 292                         continue;
 293                 }
 294                 burst_count = i2c_nuvoton_get_burstcount(client, chip);
 295                 if (burst_count < 0) {
 296                         dev_err(dev, "%s() fail to get burstCount\n", __func__);
 297                         size = -EIO;
 298                         continue;
 299                 }
 300                 size = i2c_nuvoton_recv_data(client, chip, buf,
 301                                              burst_count);
 302                 if (size < TPM_HEADER_SIZE) {
 303                         dev_err(dev, "%s() fail to read header\n", __func__);
 304                         size = -EIO;
 305                         continue;
 306                 }
 307                 /*
 308                  * convert number of expected bytes field from big endian 32 bit
 309                  * to machine native
 310                  */
 311                 expected = be32_to_cpu(*(__be32 *) (buf + 2));
 312                 if (expected > count) {
 313                         dev_err(dev, "%s() expected > count\n", __func__);
 314                         size = -EIO;
 315                         continue;
 316                 }
 317                 rc = i2c_nuvoton_recv_data(client, chip, &buf[size],
 318                                            expected - size);
 319                 size += rc;
 320                 if (rc < 0 || size < expected) {
 321                         dev_err(dev, "%s() fail to read remainder of result\n",
 322                                 __func__);
 323                         size = -EIO;
 324                         continue;
 325                 }
 326                 if (i2c_nuvoton_wait_for_stat(
 327                             chip, TPM_STS_VALID | TPM_STS_DATA_AVAIL,
 328                             TPM_STS_VALID, chip->vendor.timeout_c,
 329                             NULL)) {
 330                         dev_err(dev, "%s() error left over data\n", __func__);
 331                         size = -ETIMEDOUT;
 332                         continue;
 333                 }
 334                 break;
 335         }
 336         i2c_nuvoton_ready(chip);
 337         dev_dbg(chip->pdev, "%s() -> %d\n", __func__, size);
 338         return size;
 339 }
 340
 341 /*
 342  * Send TPM command.
 343  *
 344  * If interrupts are used (signaled by an irq set in the vendor structure)
 345  * tpm.c can skip polling for the data to be available as the interrupt is
 346  * waited for here
 347  */
 348 static int i2c_nuvoton_send(struct tpm_chip *chip, u8 *buf, size_t len)
 349 {
 350         struct device *dev = chip->pdev;
 351         struct i2c_client *client = to_i2c_client(dev);
 352         u32 ordinal;
 353         size_t count = 0;
 354         int burst_count, bytes2write, retries, rc = -EIO;
 355
 356         for (retries = 0; retries < TPM_RETRY; retries++) {
 357                 i2c_nuvoton_ready(chip);
 358                 if (i2c_nuvoton_wait_for_stat(chip, TPM_STS_COMMAND_READY,
 359                                               TPM_STS_COMMAND_READY,
 360                                               chip->vendor.timeout_b, NULL)) {
 361                         dev_err(dev, "%s() timeout on commandReady\n",
 362                                 __func__);
 363                         rc = -EIO;
 364                         continue;
 365                 }
 366                 rc = 0;
 367                 while (count < len - 1) {
 368                         burst_count = i2c_nuvoton_get_burstcount(client,
 369                                                                  chip);
 370                         if (burst_count < 0) {
 371                                 dev_err(dev, "%s() fail get burstCount\n",
 372                                         __func__);
 373                                 rc = -EIO;
 374                                 break;
 375                         }
 376                         bytes2write = min_t(size_t, burst_count,
 377                                             len - 1 - count);
 378                         rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W,
 379                                                    bytes2write, &buf[count]);
 380                         if (rc < 0) {
 381                                 dev_err(dev, "%s() fail i2cWriteBuf\n",
 382                                         __func__);
 383                                 break;
 384                         }
 385                         dev_dbg(dev, "%s(%d):", __func__, bytes2write);
 386                         count += bytes2write;
 387                         rc = i2c_nuvoton_wait_for_stat(chip,
 388                                                        TPM_STS_VALID |
 389                                                        TPM_STS_EXPECT,
 390                                                        TPM_STS_VALID |
 391                                                        TPM_STS_EXPECT,
 392                                                        chip->vendor.timeout_c,
 393                                                        NULL);
 394                         if (rc < 0) {
 395                                 dev_err(dev, "%s() timeout on Expect\n",
 396                                         __func__);
 397                                 rc = -ETIMEDOUT;
 398                                 break;
 399                         }
 400                 }
 401                 if (rc < 0)
 402                         continue;
 403
 404                 /* write last byte */
 405                 rc = i2c_nuvoton_write_buf(client, TPM_DATA_FIFO_W, 1,
 406                                            &buf[count]);
 407                 if (rc < 0) {
 408                         dev_err(dev, "%s() fail to write last byte\n",
 409                                 __func__);
 410                         rc = -EIO;
 411                         continue;
 412                 }
 413                 dev_dbg(dev, "%s(last): %02x", __func__, buf[count]);
 414                 rc = i2c_nuvoton_wait_for_stat(chip,
 415                                                TPM_STS_VALID | TPM_STS_EXPECT,
 416                                                TPM_STS_VALID,
 417                                                chip->vendor.timeout_c, NULL);
 418                 if (rc) {
 419                         dev_err(dev, "%s() timeout on Expect to clear\n",
 420                                 __func__);
 421                         rc = -ETIMEDOUT;
 422                         continue;
 423                 }
 424                 break;
 425         }
 426         if (rc < 0) {
 427                 /* retries == TPM_RETRY */
 428                 i2c_nuvoton_ready(chip);
 429                 return rc;
 430         }
 431         /* execute the TPM command */
 432         rc = i2c_nuvoton_write_status(client, TPM_STS_GO);
 433         if (rc < 0) {
 434                 dev_err(dev, "%s() fail to write Go\n", __func__);
 435                 i2c_nuvoton_ready(chip);
 436                 return rc;
 437         }
 438         ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
 439         rc = i2c_nuvoton_wait_for_data_avail(chip,
 440                                              tpm_calc_ordinal_duration(chip,
 441                                                                        ordinal),
 442                                              &chip->vendor.read_queue);
 443         if (rc) {
 444                 dev_err(dev, "%s() timeout command duration\n", __func__);
 445                 i2c_nuvoton_ready(chip);
 446                 return rc;
 447         }
 448
 449         dev_dbg(dev, "%s() -> %zd\n", __func__, len);
 450         return len;
 451 }
 452
 453 static bool i2c_nuvoton_req_canceled(struct tpm_chip *chip, u8 status)
 454 {
 455         return (status == TPM_STS_COMMAND_READY);
 456 }
 457
 458 static const struct tpm_class_ops tpm_i2c = {
 459         .status = i2c_nuvoton_read_status,
 460         .recv = i2c_nuvoton_recv,
 461         .send = i2c_nuvoton_send,
 462         .cancel = i2c_nuvoton_ready,
 463         .req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 464         .req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 465         .req_canceled = i2c_nuvoton_req_canceled,
 466 };
 467
 468 /* The only purpose for the handler is to signal to any waiting threads that
 469  * the interrupt is currently being asserted. The driver does not do any
 470  * processing triggered by interrupts, and the chip provides no way to mask at
 471  * the source (plus that would be slow over I2C). Run the IRQ as a one-shot,
 472  * this means it cannot be shared. */
 473 static irqreturn_t i2c_nuvoton_int_handler(int dummy, void *dev_id)
 474 {
 475         struct tpm_chip *chip = dev_id;
 476         struct priv_data *priv = chip->vendor.priv;
 477
 478         priv->intrs++;
 479         wake_up(&chip->vendor.read_queue);
 480         disable_irq_nosync(chip->vendor.irq);
 481         return IRQ_HANDLED;
 482 }
 483
 484 static int get_vid(struct i2c_client *client, u32 *res)
 485 {
 486         static const u8 vid_did_rid_value[] = { 0x50, 0x10, 0xfe };
 487         u32 temp;
 488         s32 rc;
 489
 490         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 491                 return -ENODEV;
 492         rc = i2c_nuvoton_read_buf(client, TPM_VID_DID_RID, 4, (u8 *)&temp);
 493         if (rc < 0)
 494                 return rc;
 495
 496         /* check WPCT301 values - ignore RID */
 497         if (memcmp(&temp, vid_did_rid_value, sizeof(vid_did_rid_value))) {
 498                 /*
 499                  * f/w rev 2.81 has an issue where the VID_DID_RID is not
 500                  * reporting the right value. so give it another chance at
 501                  * offset 0x20 (FIFO_W).
 502                  */
 503                 rc = i2c_nuvoton_read_buf(client, TPM_DATA_FIFO_W, 4,
 504                                           (u8 *) (&temp));
 505                 if (rc < 0)
 506                         return rc;
 507
 508                 /* check WPCT301 values - ignore RID */
 509                 if (memcmp(&temp, vid_did_rid_value,
 510                            sizeof(vid_did_rid_value)))
 511                         return -ENODEV;
 512         }
 513
 514         *res = temp;
 515         return 0;
 516 }
 517
 518 static int i2c_nuvoton_probe(struct i2c_client *client,
 519                              const struct i2c_device_id *id)
 520 {
 521         int rc;
 522         struct tpm_chip *chip;
 523         struct device *dev = &client->dev;
 524         u32 vid = 0;
 525
 526         rc = get_vid(client, &vid);
 527         if (rc)
 528                 return rc;
 529
 530         dev_info(dev, "VID: %04X DID: %02X RID: %02X\n", (u16) vid,
 531                  (u8) (vid >> 16), (u8) (vid >> 24));
 532
 533         chip = tpmm_chip_alloc(dev, &tpm_i2c);
 534         if (IS_ERR(chip))
 535                 return PTR_ERR(chip);
 536
 537         chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data),
 538                                          GFP_KERNEL);
 539         if (!chip->vendor.priv)
 540                 return -ENOMEM;
 541
 542         init_waitqueue_head(&chip->vendor.read_queue);
 543         init_waitqueue_head(&chip->vendor.int_queue);
 544
 545         /* Default timeouts */
 546         chip->vendor.timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
 547         chip->vendor.timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
 548         chip->vendor.timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
 549         chip->vendor.timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
 550
 551         /*
 552          * I2C intfcaps (interrupt capabilitieis) in the chip are hard coded to:
 553          *   TPM_INTF_INT_LEVEL_LOW | TPM_INTF_DATA_AVAIL_INT
 554          * The IRQ should be set in the i2c_board_info (which is done
 555          * automatically in of_i2c_register_devices, for device tree users */
 556         chip->vendor.irq = client->irq;
 557
 558         if (chip->vendor.irq) {
 559                 dev_dbg(dev, "%s() chip-vendor.irq\n", __func__);
 560                 rc = devm_request_irq(dev, chip->vendor.irq,
 561                                       i2c_nuvoton_int_handler,
 562                                       IRQF_TRIGGER_LOW,
 563                                       chip->devname,
 564                                       chip);
 565                 if (rc) {
 566                         dev_err(dev, "%s() Unable to request irq: %d for use\n",
 567                                 __func__, chip->vendor.irq);
 568                         chip->vendor.irq = 0;
 569                 } else {
 570                         /* Clear any pending interrupt */
 571                         i2c_nuvoton_ready(chip);
 572                         /* - wait for TPM_STS==0xA0 (stsValid, commandReady) */
 573                         rc = i2c_nuvoton_wait_for_stat(chip,
 574                                                        TPM_STS_COMMAND_READY,
 575                                                        TPM_STS_COMMAND_READY,
 576                                                        chip->vendor.timeout_b,
 577                                                        NULL);
 578                         if (rc == 0) {
 579                                 /*
 580                                  * TIS is in ready state
 581                                  * write dummy byte to enter reception state
 582                                  * TPM_DATA_FIFO_W <- rc (0)
 583                                  */
 584                                 rc = i2c_nuvoton_write_buf(client,
 585                                                            TPM_DATA_FIFO_W,
 586                                                            1, (u8 *) (&rc));
 587                                 if (rc < 0)
 588                                         return rc;
 589                                 /* TPM_STS <- 0x40 (commandReady) */
 590                                 i2c_nuvoton_ready(chip);
 591                         } else {
 592                                 /*
 593                                  * timeout_b reached - command was
 594                                  * aborted. TIS should now be in idle state -
 595                                  * only TPM_STS_VALID should be set
 596                                  */
 597                                 if (i2c_nuvoton_read_status(chip) !=
 598                                     TPM_STS_VALID)
 599                                         return -EIO;
 600                         }
 601                 }
 602         }
 603
 604         if (tpm_get_timeouts(chip))
 605                 return -ENODEV;
 606
 607         if (tpm_do_selftest(chip))
 608                 return -ENODEV;
 609
 610         return tpm_chip_register(chip);
 611 }
 612
 613 static int i2c_nuvoton_remove(struct i2c_client *client)
 614 {
 615         struct device *dev = &(client->dev);
 616         struct tpm_chip *chip = dev_get_drvdata(dev);
 617         tpm_chip_unregister(chip);
 618         return 0;
 619 }
 620
 621 static const struct i2c_device_id i2c_nuvoton_id[] = {
 622         {I2C_DRIVER_NAME, 0},
 623         {}
 624 };
 625 MODULE_DEVICE_TABLE(i2c, i2c_nuvoton_id);
 626
 627 #ifdef CONFIG_OF
 628 static const struct of_device_id i2c_nuvoton_of_match[] = {
 629         {.compatible = "nuvoton,npct501"},
 630         {.compatible = "winbond,wpct301"},
 631         {},
 632 };
 633 MODULE_DEVICE_TABLE(of, i2c_nuvoton_of_match);
 634 #endif
 635
 636 static SIMPLE_DEV_PM_OPS(i2c_nuvoton_pm_ops, tpm_pm_suspend, tpm_pm_resume);
 637
 638 static struct i2c_driver i2c_nuvoton_driver = {
 639         .id_table = i2c_nuvoton_id,
 640         .probe = i2c_nuvoton_probe,
 641         .remove = i2c_nuvoton_remove,
 642         .driver = {
 643                 .name = I2C_DRIVER_NAME,
 644                 .owner = THIS_MODULE,
 645                 .pm = &i2c_nuvoton_pm_ops,
 646                 .of_match_table = of_match_ptr(i2c_nuvoton_of_match),
 647         },
 648 };
 649
 650 module_i2c_driver(i2c_nuvoton_driver);
 651
 652 MODULE_AUTHOR("Dan Morav ([email protected])");
 653 MODULE_DESCRIPTION("Nuvoton TPM I2C Driver");
 654 MODULE_LICENSE("GPL");