drivers/char/hw_random/n2-drv.c

   1 /* n2-drv.c: Niagara-2 RNG driver.
   2  *
   3  * Copyright (C) 2008, 2011 David S. Miller <[email protected]>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/types.h>
   9 #include <linux/delay.h>
  10 #include <linux/slab.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/preempt.h>
  13 #include <linux/hw_random.h>
  14
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17
  18 #include <asm/hypervisor.h>
  19
  20 #include "n2rng.h"
  21
  22 #define DRV_MODULE_NAME         "n2rng"
  23 #define PFX DRV_MODULE_NAME     ": "
  24 #define DRV_MODULE_VERSION      "0.2"
  25 #define DRV_MODULE_RELDATE      "July 27, 2011"
  26
  27 static char version[] =
  28         DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
  29
  30 MODULE_AUTHOR("David S. Miller ([email protected])");
  31 MODULE_DESCRIPTION("Niagara2 RNG driver");
  32 MODULE_LICENSE("GPL");
  33 MODULE_VERSION(DRV_MODULE_VERSION);
  34
  35 /* The Niagara2 RNG provides a 64-bit read-only random number
  36  * register, plus a control register.  Access to the RNG is
  37  * virtualized through the hypervisor so that both guests and control
  38  * nodes can access the device.
  39  *
  40  * The entropy source consists of raw entropy sources, each
  41  * constructed from a voltage controlled oscillator whose phase is
  42  * jittered by thermal noise sources.
  43  *
  44  * The oscillator in each of the three raw entropy sources run at
  45  * different frequencies.  Normally, all three generator outputs are
  46  * gathered, xored together, and fed into a CRC circuit, the output of
  47  * which is the 64-bit read-only register.
  48  *
  49  * Some time is necessary for all the necessary entropy to build up
  50  * such that a full 64-bits of entropy are available in the register.
  51  * In normal operating mode (RNG_CTL_LFSR is set), the chip implements
  52  * an interlock which blocks register reads until sufficient entropy
  53  * is available.
  54  *
  55  * A control register is provided for adjusting various aspects of RNG
  56  * operation, and to enable diagnostic modes.  Each of the three raw
  57  * entropy sources has an enable bit (RNG_CTL_ES{1,2,3}).  Also
  58  * provided are fields for controlling the minimum time in cycles
  59  * between read accesses to the register (RNG_CTL_WAIT, this controls
  60  * the interlock described in the previous paragraph).
  61  *
  62  * The standard setting is to have the mode bit (RNG_CTL_LFSR) set,
  63  * all three entropy sources enabled, and the interlock time set
  64  * appropriately.
  65  *
  66  * The CRC polynomial used by the chip is:
  67  *
  68  * P(X) = x64 + x61 + x57 + x56 + x52 + x51 + x50 + x48 + x47 + x46 +
  69  *        x43 + x42 + x41 + x39 + x38 + x37 + x35 + x32 + x28 + x25 +
  70  *        x22 + x21 + x17 + x15 + x13 + x12 + x11 + x7 + x5 + x + 1
  71  *
  72  * The RNG_CTL_VCO value of each noise cell must be programmed
  73  * separately.  This is why 4 control register values must be provided
  74  * to the hypervisor.  During a write, the hypervisor writes them all,
  75  * one at a time, to the actual RNG_CTL register.  The first three
  76  * values are used to setup the desired RNG_CTL_VCO for each entropy
  77  * source, for example:
  78  *
  79  *      control 0: (1 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES1
  80  *      control 1: (2 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES2
  81  *      control 2: (3 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES3
  82  *
  83  * And then the fourth value sets the final chip state and enables
  84  * desired.
  85  */
  86
  87 static int n2rng_hv_err_trans(unsigned long hv_err)
  88 {
  89         switch (hv_err) {
  90         case HV_EOK:
  91                 return 0;
  92         case HV_EWOULDBLOCK:
  93                 return -EAGAIN;
  94         case HV_ENOACCESS:
  95                 return -EPERM;
  96         case HV_EIO:
  97                 return -EIO;
  98         case HV_EBUSY:
  99                 return -EBUSY;
 100         case HV_EBADALIGN:
 101         case HV_ENORADDR:
 102                 return -EFAULT;
 103         default:
 104                 return -EINVAL;
 105         }
 106 }
 107
 108 static unsigned long n2rng_generic_read_control_v2(unsigned long ra,
 109                                                    unsigned long unit)
 110 {
 111         unsigned long hv_err, state, ticks, watchdog_delta, watchdog_status;
 112         int block = 0, busy = 0;
 113
 114         while (1) {
 115                 hv_err = sun4v_rng_ctl_read_v2(ra, unit, &state,
 116                                                &ticks,
 117                                                &watchdog_delta,
 118                                                &watchdog_status);
 119                 if (hv_err == HV_EOK)
 120                         break;
 121
 122                 if (hv_err == HV_EBUSY) {
 123                         if (++busy >= N2RNG_BUSY_LIMIT)
 124                                 break;
 125
 126                         udelay(1);
 127                 } else if (hv_err == HV_EWOULDBLOCK) {
 128                         if (++block >= N2RNG_BLOCK_LIMIT)
 129                                 break;
 130
 131                         __delay(ticks);
 132                 } else
 133                         break;
 134         }
 135
 136         return hv_err;
 137 }
 138
 139 /* In multi-socket situations, the hypervisor might need to
 140  * queue up the RNG control register write if it's for a unit
 141  * that is on a cpu socket other than the one we are executing on.
 142  *
 143  * We poll here waiting for a successful read of that control
 144  * register to make sure the write has been actually performed.
 145  */
 146 static unsigned long n2rng_control_settle_v2(struct n2rng *np, int unit)
 147 {
 148         unsigned long ra = __pa(&np->scratch_control[0]);
 149
 150         return n2rng_generic_read_control_v2(ra, unit);
 151 }
 152
 153 static unsigned long n2rng_write_ctl_one(struct n2rng *np, int unit,
 154                                          unsigned long state,
 155                                          unsigned long control_ra,
 156                                          unsigned long watchdog_timeout,
 157                                          unsigned long *ticks)
 158 {
 159         unsigned long hv_err;
 160
 161         if (np->hvapi_major == 1) {
 162                 hv_err = sun4v_rng_ctl_write_v1(control_ra, state,
 163                                                 watchdog_timeout, ticks);
 164         } else {
 165                 hv_err = sun4v_rng_ctl_write_v2(control_ra, state,
 166                                                 watchdog_timeout, unit);
 167                 if (hv_err == HV_EOK)
 168                         hv_err = n2rng_control_settle_v2(np, unit);
 169                 *ticks = N2RNG_ACCUM_CYCLES_DEFAULT;
 170         }
 171
 172         return hv_err;
 173 }
 174
 175 static int n2rng_generic_read_data(unsigned long data_ra)
 176 {
 177         unsigned long ticks, hv_err;
 178         int block = 0, hcheck = 0;
 179
 180         while (1) {
 181                 hv_err = sun4v_rng_data_read(data_ra, &ticks);
 182                 if (hv_err == HV_EOK)
 183                         return 0;
 184
 185                 if (hv_err == HV_EWOULDBLOCK) {
 186                         if (++block >= N2RNG_BLOCK_LIMIT)
 187                                 return -EWOULDBLOCK;
 188                         __delay(ticks);
 189                 } else if (hv_err == HV_ENOACCESS) {
 190                         return -EPERM;
 191                 } else if (hv_err == HV_EIO) {
 192                         if (++hcheck >= N2RNG_HCHECK_LIMIT)
 193                                 return -EIO;
 194                         udelay(10000);
 195                 } else
 196                         return -ENODEV;
 197         }
 198 }
 199
 200 static unsigned long n2rng_read_diag_data_one(struct n2rng *np,
 201                                               unsigned long unit,
 202                                               unsigned long data_ra,
 203                                               unsigned long data_len,
 204                                               unsigned long *ticks)
 205 {
 206         unsigned long hv_err;
 207
 208         if (np->hvapi_major == 1) {
 209                 hv_err = sun4v_rng_data_read_diag_v1(data_ra, data_len, ticks);
 210         } else {
 211                 hv_err = sun4v_rng_data_read_diag_v2(data_ra, data_len,
 212                                                      unit, ticks);
 213                 if (!*ticks)
 214                         *ticks = N2RNG_ACCUM_CYCLES_DEFAULT;
 215         }
 216         return hv_err;
 217 }
 218
 219 static int n2rng_generic_read_diag_data(struct n2rng *np,
 220                                         unsigned long unit,
 221                                         unsigned long data_ra,
 222                                         unsigned long data_len)
 223 {
 224         unsigned long ticks, hv_err;
 225         int block = 0;
 226
 227         while (1) {
 228                 hv_err = n2rng_read_diag_data_one(np, unit,
 229                                                   data_ra, data_len,
 230                                                   &ticks);
 231                 if (hv_err == HV_EOK)
 232                         return 0;
 233
 234                 if (hv_err == HV_EWOULDBLOCK) {
 235                         if (++block >= N2RNG_BLOCK_LIMIT)
 236                                 return -EWOULDBLOCK;
 237                         __delay(ticks);
 238                 } else if (hv_err == HV_ENOACCESS) {
 239                         return -EPERM;
 240                 } else if (hv_err == HV_EIO) {
 241                         return -EIO;
 242                 } else
 243                         return -ENODEV;
 244         }
 245 }
 246
 247
 248 static int n2rng_generic_write_control(struct n2rng *np,
 249                                        unsigned long control_ra,
 250                                        unsigned long unit,
 251                                        unsigned long state)
 252 {
 253         unsigned long hv_err, ticks;
 254         int block = 0, busy = 0;
 255
 256         while (1) {
 257                 hv_err = n2rng_write_ctl_one(np, unit, state, control_ra,
 258                                              np->wd_timeo, &ticks);
 259                 if (hv_err == HV_EOK)
 260                         return 0;
 261
 262                 if (hv_err == HV_EWOULDBLOCK) {
 263                         if (++block >= N2RNG_BLOCK_LIMIT)
 264                                 return -EWOULDBLOCK;
 265                         __delay(ticks);
 266                 } else if (hv_err == HV_EBUSY) {
 267                         if (++busy >= N2RNG_BUSY_LIMIT)
 268                                 return -EBUSY;
 269                         udelay(1);
 270                 } else
 271                         return -ENODEV;
 272         }
 273 }
 274
 275 /* Just try to see if we can successfully access the control register
 276  * of the RNG on the domain on which we are currently executing.
 277  */
 278 static int n2rng_try_read_ctl(struct n2rng *np)
 279 {
 280         unsigned long hv_err;
 281         unsigned long x;
 282
 283         if (np->hvapi_major == 1) {
 284                 hv_err = sun4v_rng_get_diag_ctl();
 285         } else {
 286                 /* We purposefully give invalid arguments, HV_NOACCESS
 287                  * is higher priority than the errors we'd get from
 288                  * these other cases, and that's the error we are
 289                  * truly interested in.
 290                  */
 291                 hv_err = sun4v_rng_ctl_read_v2(0UL, ~0UL, &x, &x, &x, &x);
 292                 switch (hv_err) {
 293                 case HV_EWOULDBLOCK:
 294                 case HV_ENOACCESS:
 295                         break;
 296                 default:
 297                         hv_err = HV_EOK;
 298                         break;
 299                 }
 300         }
 301
 302         return n2rng_hv_err_trans(hv_err);
 303 }
 304
 305 #define CONTROL_DEFAULT_BASE            \
 306         ((2 << RNG_CTL_ASEL_SHIFT) |    \
 307          (N2RNG_ACCUM_CYCLES_DEFAULT << RNG_CTL_WAIT_SHIFT) |   \
 308          RNG_CTL_LFSR)
 309
 310 #define CONTROL_DEFAULT_0               \
 311         (CONTROL_DEFAULT_BASE |         \
 312          (1 << RNG_CTL_VCO_SHIFT) |     \
 313          RNG_CTL_ES1)
 314 #define CONTROL_DEFAULT_1               \
 315         (CONTROL_DEFAULT_BASE |         \
 316          (2 << RNG_CTL_VCO_SHIFT) |     \
 317          RNG_CTL_ES2)
 318 #define CONTROL_DEFAULT_2               \
 319         (CONTROL_DEFAULT_BASE |         \
 320          (3 << RNG_CTL_VCO_SHIFT) |     \
 321          RNG_CTL_ES3)
 322 #define CONTROL_DEFAULT_3               \
 323         (CONTROL_DEFAULT_BASE |         \
 324          RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3)
 325
 326 static void n2rng_control_swstate_init(struct n2rng *np)
 327 {
 328         int i;
 329
 330         np->flags |= N2RNG_FLAG_CONTROL;
 331
 332         np->health_check_sec = N2RNG_HEALTH_CHECK_SEC_DEFAULT;
 333         np->accum_cycles = N2RNG_ACCUM_CYCLES_DEFAULT;
 334         np->wd_timeo = N2RNG_WD_TIMEO_DEFAULT;
 335
 336         for (i = 0; i < np->num_units; i++) {
 337                 struct n2rng_unit *up = &np->units[i];
 338
 339                 up->control[0] = CONTROL_DEFAULT_0;
 340                 up->control[1] = CONTROL_DEFAULT_1;
 341                 up->control[2] = CONTROL_DEFAULT_2;
 342                 up->control[3] = CONTROL_DEFAULT_3;
 343         }
 344
 345         np->hv_state = HV_RNG_STATE_UNCONFIGURED;
 346 }
 347
 348 static int n2rng_grab_diag_control(struct n2rng *np)
 349 {
 350         int i, busy_count, err = -ENODEV;
 351
 352         busy_count = 0;
 353         for (i = 0; i < 100; i++) {
 354                 err = n2rng_try_read_ctl(np);
 355                 if (err != -EAGAIN)
 356                         break;
 357
 358                 if (++busy_count > 100) {
 359                         dev_err(&np->op->dev,
 360                                 "Grab diag control timeout.\n");
 361                         return -ENODEV;
 362                 }
 363
 364                 udelay(1);
 365         }
 366
 367         return err;
 368 }
 369
 370 static int n2rng_init_control(struct n2rng *np)
 371 {
 372         int err = n2rng_grab_diag_control(np);
 373
 374         /* Not in the control domain, that's OK we are only a consumer
 375          * of the RNG data, we don't setup and program it.
 376          */
 377         if (err == -EPERM)
 378                 return 0;
 379         if (err)
 380                 return err;
 381
 382         n2rng_control_swstate_init(np);
 383
 384         return 0;
 385 }
 386
 387 static int n2rng_data_read(struct hwrng *rng, u32 *data)
 388 {
 389         struct n2rng *np = (struct n2rng *) rng->priv;
 390         unsigned long ra = __pa(&np->test_data);
 391         int len;
 392
 393         if (!(np->flags & N2RNG_FLAG_READY)) {
 394                 len = 0;
 395         } else if (np->flags & N2RNG_FLAG_BUFFER_VALID) {
 396                 np->flags &= ~N2RNG_FLAG_BUFFER_VALID;
 397                 *data = np->buffer;
 398                 len = 4;
 399         } else {
 400                 int err = n2rng_generic_read_data(ra);
 401                 if (!err) {
 402                         np->buffer = np->test_data >> 32;
 403                         *data = np->test_data & 0xffffffff;
 404                         len = 4;
 405                 } else {
 406                         dev_err(&np->op->dev, "RNG error, restesting\n");
 407                         np->flags &= ~N2RNG_FLAG_READY;
 408                         if (!(np->flags & N2RNG_FLAG_SHUTDOWN))
 409                                 schedule_delayed_work(&np->work, 0);
 410                         len = 0;
 411                 }
 412         }
 413
 414         return len;
 415 }
 416
 417 /* On a guest node, just make sure we can read random data properly.
 418  * If a control node reboots or reloads it's n2rng driver, this won't
 419  * work during that time.  So we have to keep probing until the device
 420  * becomes usable.
 421  */
 422 static int n2rng_guest_check(struct n2rng *np)
 423 {
 424         unsigned long ra = __pa(&np->test_data);
 425
 426         return n2rng_generic_read_data(ra);
 427 }
 428
 429 static int n2rng_entropy_diag_read(struct n2rng *np, unsigned long unit,
 430                                    u64 *pre_control, u64 pre_state,
 431                                    u64 *buffer, unsigned long buf_len,
 432                                    u64 *post_control, u64 post_state)
 433 {
 434         unsigned long post_ctl_ra = __pa(post_control);
 435         unsigned long pre_ctl_ra = __pa(pre_control);
 436         unsigned long buffer_ra = __pa(buffer);
 437         int err;
 438
 439         err = n2rng_generic_write_control(np, pre_ctl_ra, unit, pre_state);
 440         if (err)
 441                 return err;
 442
 443         err = n2rng_generic_read_diag_data(np, unit,
 444                                            buffer_ra, buf_len);
 445
 446         (void) n2rng_generic_write_control(np, post_ctl_ra, unit,
 447                                            post_state);
 448
 449         return err;
 450 }
 451
 452 static u64 advance_polynomial(u64 poly, u64 val, int count)
 453 {
 454         int i;
 455
 456         for (i = 0; i < count; i++) {
 457                 int highbit_set = ((s64)val < 0);
 458
 459                 val <<= 1;
 460                 if (highbit_set)
 461                         val ^= poly;
 462         }
 463
 464         return val;
 465 }
 466
 467 static int n2rng_test_buffer_find(struct n2rng *np, u64 val)
 468 {
 469         int i, count = 0;
 470
 471         /* Purposefully skip over the first word.  */
 472         for (i = 1; i < SELFTEST_BUFFER_WORDS; i++) {
 473                 if (np->test_buffer[i] == val)
 474                         count++;
 475         }
 476         return count;
 477 }
 478
 479 static void n2rng_dump_test_buffer(struct n2rng *np)
 480 {
 481         int i;
 482
 483         for (i = 0; i < SELFTEST_BUFFER_WORDS; i++)
 484                 dev_err(&np->op->dev, "Test buffer slot %d [0x%016llx]\n",
 485                         i, np->test_buffer[i]);
 486 }
 487
 488 static int n2rng_check_selftest_buffer(struct n2rng *np, unsigned long unit)
 489 {
 490         u64 val = SELFTEST_VAL;
 491         int err, matches, limit;
 492
 493         matches = 0;
 494         for (limit = 0; limit < SELFTEST_LOOPS_MAX; limit++) {
 495                 matches += n2rng_test_buffer_find(np, val);
 496                 if (matches >= SELFTEST_MATCH_GOAL)
 497                         break;
 498                 val = advance_polynomial(SELFTEST_POLY, val, 1);
 499         }
 500
 501         err = 0;
 502         if (limit >= SELFTEST_LOOPS_MAX) {
 503                 err = -ENODEV;
 504                 dev_err(&np->op->dev, "Selftest failed on unit %lu\n", unit);
 505                 n2rng_dump_test_buffer(np);
 506         } else
 507                 dev_info(&np->op->dev, "Selftest passed on unit %lu\n", unit);
 508
 509         return err;
 510 }
 511
 512 static int n2rng_control_selftest(struct n2rng *np, unsigned long unit)
 513 {
 514         int err;
 515
 516         np->test_control[0] = (0x2 << RNG_CTL_ASEL_SHIFT);
 517         np->test_control[1] = (0x2 << RNG_CTL_ASEL_SHIFT);
 518         np->test_control[2] = (0x2 << RNG_CTL_ASEL_SHIFT);
 519         np->test_control[3] = ((0x2 << RNG_CTL_ASEL_SHIFT) |
 520                                RNG_CTL_LFSR |
 521                                ((SELFTEST_TICKS - 2) << RNG_CTL_WAIT_SHIFT));
 522
 523
 524         err = n2rng_entropy_diag_read(np, unit, np->test_control,
 525                                       HV_RNG_STATE_HEALTHCHECK,
 526                                       np->test_buffer,
 527                                       sizeof(np->test_buffer),
 528                                       &np->units[unit].control[0],
 529                                       np->hv_state);
 530         if (err)
 531                 return err;
 532
 533         return n2rng_check_selftest_buffer(np, unit);
 534 }
 535
 536 static int n2rng_control_check(struct n2rng *np)
 537 {
 538         int i;
 539
 540         for (i = 0; i < np->num_units; i++) {
 541                 int err = n2rng_control_selftest(np, i);
 542                 if (err)
 543                         return err;
 544         }
 545         return 0;
 546 }
 547
 548 /* The sanity checks passed, install the final configuration into the
 549  * chip, it's ready to use.
 550  */
 551 static int n2rng_control_configure_units(struct n2rng *np)
 552 {
 553         int unit, err;
 554
 555         err = 0;
 556         for (unit = 0; unit < np->num_units; unit++) {
 557                 struct n2rng_unit *up = &np->units[unit];
 558                 unsigned long ctl_ra = __pa(&up->control[0]);
 559                 int esrc;
 560                 u64 base;
 561
 562                 base = ((np->accum_cycles << RNG_CTL_WAIT_SHIFT) |
 563                         (2 << RNG_CTL_ASEL_SHIFT) |
 564                         RNG_CTL_LFSR);
 565
 566                 /* XXX This isn't the best.  We should fetch a bunch
 567                  * XXX of words using each entropy source combined XXX
 568                  * with each VCO setting, and see which combinations
 569                  * XXX give the best random data.
 570                  */
 571                 for (esrc = 0; esrc < 3; esrc++)
 572                         up->control[esrc] = base |
 573                                 (esrc << RNG_CTL_VCO_SHIFT) |
 574                                 (RNG_CTL_ES1 << esrc);
 575
 576                 up->control[3] = base |
 577                         (RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3);
 578
 579                 err = n2rng_generic_write_control(np, ctl_ra, unit,
 580                                                   HV_RNG_STATE_CONFIGURED);
 581                 if (err)
 582                         break;
 583         }
 584
 585         return err;
 586 }
 587
 588 static void n2rng_work(struct work_struct *work)
 589 {
 590         struct n2rng *np = container_of(work, struct n2rng, work.work);
 591         int err = 0;
 592
 593         if (!(np->flags & N2RNG_FLAG_CONTROL)) {
 594                 err = n2rng_guest_check(np);
 595         } else {
 596                 preempt_disable();
 597                 err = n2rng_control_check(np);
 598                 preempt_enable();
 599
 600                 if (!err)
 601                         err = n2rng_control_configure_units(np);
 602         }
 603
 604         if (!err) {
 605                 np->flags |= N2RNG_FLAG_READY;
 606                 dev_info(&np->op->dev, "RNG ready\n");
 607         }
 608
 609         if (err && !(np->flags & N2RNG_FLAG_SHUTDOWN))
 610                 schedule_delayed_work(&np->work, HZ * 2);
 611 }
 612
 613 static void n2rng_driver_version(void)
 614 {
 615         static int n2rng_version_printed;
 616
 617         if (n2rng_version_printed++ == 0)
 618                 pr_info("%s", version);
 619 }
 620
 621 static const struct of_device_id n2rng_match[];
 622 static int n2rng_probe(struct platform_device *op)
 623 {
 624         const struct of_device_id *match;
 625         int multi_capable;
 626         int err = -ENOMEM;
 627         struct n2rng *np;
 628
 629         match = of_match_device(n2rng_match, &op->dev);
 630         if (!match)
 631                 return -EINVAL;
 632         multi_capable = (match->data != NULL);
 633
 634         n2rng_driver_version();
 635         np = kzalloc(sizeof(*np), GFP_KERNEL);
 636         if (!np)
 637                 goto out;
 638         np->op = op;
 639
 640         INIT_DELAYED_WORK(&np->work, n2rng_work);
 641
 642         if (multi_capable)
 643                 np->flags |= N2RNG_FLAG_MULTI;
 644
 645         err = -ENODEV;
 646         np->hvapi_major = 2;
 647         if (sun4v_hvapi_register(HV_GRP_RNG,
 648                                  np->hvapi_major,
 649                                  &np->hvapi_minor)) {
 650                 np->hvapi_major = 1;
 651                 if (sun4v_hvapi_register(HV_GRP_RNG,
 652                                          np->hvapi_major,
 653                                          &np->hvapi_minor)) {
 654                         dev_err(&op->dev, "Cannot register suitable "
 655                                 "HVAPI version.\n");
 656                         goto out_free;
 657                 }
 658         }
 659
 660         if (np->flags & N2RNG_FLAG_MULTI) {
 661                 if (np->hvapi_major < 2) {
 662                         dev_err(&op->dev, "multi-unit-capable RNG requires "
 663                                 "HVAPI major version 2 or later, got %lu\n",
 664                                 np->hvapi_major);
 665                         goto out_hvapi_unregister;
 666                 }
 667                 np->num_units = of_getintprop_default(op->dev.of_node,
 668                                                       "rng-#units", 0);
 669                 if (!np->num_units) {
 670                         dev_err(&op->dev, "VF RNG lacks rng-#units property\n");
 671                         goto out_hvapi_unregister;
 672                 }
 673         } else
 674                 np->num_units = 1;
 675
 676         dev_info(&op->dev, "Registered RNG HVAPI major %lu minor %lu\n",
 677                  np->hvapi_major, np->hvapi_minor);
 678
 679         np->units = kzalloc(sizeof(struct n2rng_unit) * np->num_units,
 680                             GFP_KERNEL);
 681         err = -ENOMEM;
 682         if (!np->units)
 683                 goto out_hvapi_unregister;
 684
 685         err = n2rng_init_control(np);
 686         if (err)
 687                 goto out_free_units;
 688
 689         dev_info(&op->dev, "Found %s RNG, units: %d\n",
 690                  ((np->flags & N2RNG_FLAG_MULTI) ?
 691                   "multi-unit-capable" : "single-unit"),
 692                  np->num_units);
 693
 694         np->hwrng.name = "n2rng";
 695         np->hwrng.data_read = n2rng_data_read;
 696         np->hwrng.priv = (unsigned long) np;
 697
 698         err = hwrng_register(&np->hwrng);
 699         if (err)
 700                 goto out_free_units;
 701
 702         platform_set_drvdata(op, np);
 703
 704         schedule_delayed_work(&np->work, 0);
 705
 706         return 0;
 707
 708 out_free_units:
 709         kfree(np->units);
 710         np->units = NULL;
 711
 712 out_hvapi_unregister:
 713         sun4v_hvapi_unregister(HV_GRP_RNG);
 714
 715 out_free:
 716         kfree(np);
 717 out:
 718         return err;
 719 }
 720
 721 static int n2rng_remove(struct platform_device *op)
 722 {
 723         struct n2rng *np = platform_get_drvdata(op);
 724
 725         np->flags |= N2RNG_FLAG_SHUTDOWN;
 726
 727         cancel_delayed_work_sync(&np->work);
 728
 729         hwrng_unregister(&np->hwrng);
 730
 731         sun4v_hvapi_unregister(HV_GRP_RNG);
 732
 733         kfree(np->units);
 734         np->units = NULL;
 735
 736         kfree(np);
 737
 738         return 0;
 739 }
 740
 741 static const struct of_device_id n2rng_match[] = {
 742         {
 743                 .name           = "random-number-generator",
 744                 .compatible     = "SUNW,n2-rng",
 745         },
 746         {
 747                 .name           = "random-number-generator",
 748                 .compatible     = "SUNW,vf-rng",
 749                 .data           = (void *) 1,
 750         },
 751         {
 752                 .name           = "random-number-generator",
 753                 .compatible     = "SUNW,kt-rng",
 754                 .data           = (void *) 1,
 755         },
 756         {},
 757 };
 758 MODULE_DEVICE_TABLE(of, n2rng_match);
 759
 760 static struct platform_driver n2rng_driver = {
 761         .driver = {
 762                 .name = "n2rng",
 763                 .owner = THIS_MODULE,
 764                 .of_match_table = n2rng_match,
 765         },
 766         .probe          = n2rng_probe,
 767         .remove         = n2rng_remove,
 768 };
 769
 770 module_platform_driver(n2rng_driver);