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n2-drv.c
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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/init.h>
11 #include <linux/slab.h>
12 #include <linux/workqueue.h>
13 #include <linux/preempt.h>
14 #include <linux/hw_random.h>
15 
16 #include <linux/of.h>
17 #include <linux/of_device.h>
18 
19 #include <asm/hypervisor.h>
20 
21 #include "n2rng.h"
22 
23 #define DRV_MODULE_NAME "n2rng"
24 #define PFX DRV_MODULE_NAME ": "
25 #define DRV_MODULE_VERSION "0.2"
26 #define DRV_MODULE_RELDATE "July 27, 2011"
27 
28 static char version[] __devinitdata =
29  DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
30 
31 MODULE_AUTHOR("David S. Miller ([email protected])");
32 MODULE_DESCRIPTION("Niagara2 RNG driver");
33 MODULE_LICENSE("GPL");
34 MODULE_VERSION(DRV_MODULE_VERSION);
35 
36 /* The Niagara2 RNG provides a 64-bit read-only random number
37  * register, plus a control register. Access to the RNG is
38  * virtualized through the hypervisor so that both guests and control
39  * nodes can access the device.
40  *
41  * The entropy source consists of raw entropy sources, each
42  * constructed from a voltage controlled oscillator whose phase is
43  * jittered by thermal noise sources.
44  *
45  * The oscillator in each of the three raw entropy sources run at
46  * different frequencies. Normally, all three generator outputs are
47  * gathered, xored together, and fed into a CRC circuit, the output of
48  * which is the 64-bit read-only register.
49  *
50  * Some time is necessary for all the necessary entropy to build up
51  * such that a full 64-bits of entropy are available in the register.
52  * In normal operating mode (RNG_CTL_LFSR is set), the chip implements
53  * an interlock which blocks register reads until sufficient entropy
54  * is available.
55  *
56  * A control register is provided for adjusting various aspects of RNG
57  * operation, and to enable diagnostic modes. Each of the three raw
58  * entropy sources has an enable bit (RNG_CTL_ES{1,2,3}). Also
59  * provided are fields for controlling the minimum time in cycles
60  * between read accesses to the register (RNG_CTL_WAIT, this controls
61  * the interlock described in the previous paragraph).
62  *
63  * The standard setting is to have the mode bit (RNG_CTL_LFSR) set,
64  * all three entropy sources enabled, and the interlock time set
65  * appropriately.
66  *
67  * The CRC polynomial used by the chip is:
68  *
69  * P(X) = x64 + x61 + x57 + x56 + x52 + x51 + x50 + x48 + x47 + x46 +
70  * x43 + x42 + x41 + x39 + x38 + x37 + x35 + x32 + x28 + x25 +
71  * x22 + x21 + x17 + x15 + x13 + x12 + x11 + x7 + x5 + x + 1
72  *
73  * The RNG_CTL_VCO value of each noise cell must be programmed
74  * separately. This is why 4 control register values must be provided
75  * to the hypervisor. During a write, the hypervisor writes them all,
76  * one at a time, to the actual RNG_CTL register. The first three
77  * values are used to setup the desired RNG_CTL_VCO for each entropy
78  * source, for example:
79  *
80  * control 0: (1 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES1
81  * control 1: (2 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES2
82  * control 2: (3 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES3
83  *
84  * And then the fourth value sets the final chip state and enables
85  * desired.
86  */
87 
88 static int n2rng_hv_err_trans(unsigned long hv_err)
89 {
90  switch (hv_err) {
91  case HV_EOK:
92  return 0;
93  case HV_EWOULDBLOCK:
94  return -EAGAIN;
95  case HV_ENOACCESS:
96  return -EPERM;
97  case HV_EIO:
98  return -EIO;
99  case HV_EBUSY:
100  return -EBUSY;
101  case HV_EBADALIGN:
102  case HV_ENORADDR:
103  return -EFAULT;
104  default:
105  return -EINVAL;
106  }
107 }
108 
109 static unsigned long n2rng_generic_read_control_v2(unsigned long ra,
110  unsigned long unit)
111 {
112  unsigned long hv_err, state, ticks, watchdog_delta, watchdog_status;
113  int block = 0, busy = 0;
114 
115  while (1) {
116  hv_err = sun4v_rng_ctl_read_v2(ra, unit, &state,
117  &ticks,
118  &watchdog_delta,
119  &watchdog_status);
120  if (hv_err == HV_EOK)
121  break;
122 
123  if (hv_err == HV_EBUSY) {
124  if (++busy >= N2RNG_BUSY_LIMIT)
125  break;
126 
127  udelay(1);
128  } else if (hv_err == HV_EWOULDBLOCK) {
129  if (++block >= N2RNG_BLOCK_LIMIT)
130  break;
131 
132  __delay(ticks);
133  } else
134  break;
135  }
136 
137  return hv_err;
138 }
139 
140 /* In multi-socket situations, the hypervisor might need to
141  * queue up the RNG control register write if it's for a unit
142  * that is on a cpu socket other than the one we are executing on.
143  *
144  * We poll here waiting for a successful read of that control
145  * register to make sure the write has been actually performed.
146  */
147 static unsigned long n2rng_control_settle_v2(struct n2rng *np, int unit)
148 {
149  unsigned long ra = __pa(&np->scratch_control[0]);
150 
151  return n2rng_generic_read_control_v2(ra, unit);
152 }
153 
154 static unsigned long n2rng_write_ctl_one(struct n2rng *np, int unit,
155  unsigned long state,
156  unsigned long control_ra,
157  unsigned long watchdog_timeout,
158  unsigned long *ticks)
159 {
160  unsigned long hv_err;
161 
162  if (np->hvapi_major == 1) {
163  hv_err = sun4v_rng_ctl_write_v1(control_ra, state,
164  watchdog_timeout, ticks);
165  } else {
166  hv_err = sun4v_rng_ctl_write_v2(control_ra, state,
167  watchdog_timeout, unit);
168  if (hv_err == HV_EOK)
169  hv_err = n2rng_control_settle_v2(np, unit);
170  *ticks = N2RNG_ACCUM_CYCLES_DEFAULT;
171  }
172 
173  return hv_err;
174 }
175 
176 static int n2rng_generic_read_data(unsigned long data_ra)
177 {
178  unsigned long ticks, hv_err;
179  int block = 0, hcheck = 0;
180 
181  while (1) {
182  hv_err = sun4v_rng_data_read(data_ra, &ticks);
183  if (hv_err == HV_EOK)
184  return 0;
185 
186  if (hv_err == HV_EWOULDBLOCK) {
187  if (++block >= N2RNG_BLOCK_LIMIT)
188  return -EWOULDBLOCK;
189  __delay(ticks);
190  } else if (hv_err == HV_ENOACCESS) {
191  return -EPERM;
192  } else if (hv_err == HV_EIO) {
193  if (++hcheck >= N2RNG_HCHECK_LIMIT)
194  return -EIO;
195  udelay(10000);
196  } else
197  return -ENODEV;
198  }
199 }
200 
201 static unsigned long n2rng_read_diag_data_one(struct n2rng *np,
202  unsigned long unit,
203  unsigned long data_ra,
204  unsigned long data_len,
205  unsigned long *ticks)
206 {
207  unsigned long hv_err;
208 
209  if (np->hvapi_major == 1) {
210  hv_err = sun4v_rng_data_read_diag_v1(data_ra, data_len, ticks);
211  } else {
212  hv_err = sun4v_rng_data_read_diag_v2(data_ra, data_len,
213  unit, ticks);
214  if (!*ticks)
215  *ticks = N2RNG_ACCUM_CYCLES_DEFAULT;
216  }
217  return hv_err;
218 }
219 
220 static int n2rng_generic_read_diag_data(struct n2rng *np,
221  unsigned long unit,
222  unsigned long data_ra,
223  unsigned long data_len)
224 {
225  unsigned long ticks, hv_err;
226  int block = 0;
227 
228  while (1) {
229  hv_err = n2rng_read_diag_data_one(np, unit,
230  data_ra, data_len,
231  &ticks);
232  if (hv_err == HV_EOK)
233  return 0;
234 
235  if (hv_err == HV_EWOULDBLOCK) {
236  if (++block >= N2RNG_BLOCK_LIMIT)
237  return -EWOULDBLOCK;
238  __delay(ticks);
239  } else if (hv_err == HV_ENOACCESS) {
240  return -EPERM;
241  } else if (hv_err == HV_EIO) {
242  return -EIO;
243  } else
244  return -ENODEV;
245  }
246 }
247 
248 
249 static int n2rng_generic_write_control(struct n2rng *np,
250  unsigned long control_ra,
251  unsigned long unit,
252  unsigned long state)
253 {
254  unsigned long hv_err, ticks;
255  int block = 0, busy = 0;
256 
257  while (1) {
258  hv_err = n2rng_write_ctl_one(np, unit, state, control_ra,
259  np->wd_timeo, &ticks);
260  if (hv_err == HV_EOK)
261  return 0;
262 
263  if (hv_err == HV_EWOULDBLOCK) {
264  if (++block >= N2RNG_BLOCK_LIMIT)
265  return -EWOULDBLOCK;
266  __delay(ticks);
267  } else if (hv_err == HV_EBUSY) {
268  if (++busy >= N2RNG_BUSY_LIMIT)
269  return -EBUSY;
270  udelay(1);
271  } else
272  return -ENODEV;
273  }
274 }
275 
276 /* Just try to see if we can successfully access the control register
277  * of the RNG on the domain on which we are currently executing.
278  */
279 static int n2rng_try_read_ctl(struct n2rng *np)
280 {
281  unsigned long hv_err;
282  unsigned long x;
283 
284  if (np->hvapi_major == 1) {
285  hv_err = sun4v_rng_get_diag_ctl();
286  } else {
287  /* We purposefully give invalid arguments, HV_NOACCESS
288  * is higher priority than the errors we'd get from
289  * these other cases, and that's the error we are
290  * truly interested in.
291  */
292  hv_err = sun4v_rng_ctl_read_v2(0UL, ~0UL, &x, &x, &x, &x);
293  switch (hv_err) {
294  case HV_EWOULDBLOCK:
295  case HV_ENOACCESS:
296  break;
297  default:
298  hv_err = HV_EOK;
299  break;
300  }
301  }
302 
303  return n2rng_hv_err_trans(hv_err);
304 }
305 
306 #define CONTROL_DEFAULT_BASE \
307  ((2 << RNG_CTL_ASEL_SHIFT) | \
308  (N2RNG_ACCUM_CYCLES_DEFAULT << RNG_CTL_WAIT_SHIFT) | \
309  RNG_CTL_LFSR)
310 
311 #define CONTROL_DEFAULT_0 \
312  (CONTROL_DEFAULT_BASE | \
313  (1 << RNG_CTL_VCO_SHIFT) | \
314  RNG_CTL_ES1)
315 #define CONTROL_DEFAULT_1 \
316  (CONTROL_DEFAULT_BASE | \
317  (2 << RNG_CTL_VCO_SHIFT) | \
318  RNG_CTL_ES2)
319 #define CONTROL_DEFAULT_2 \
320  (CONTROL_DEFAULT_BASE | \
321  (3 << RNG_CTL_VCO_SHIFT) | \
322  RNG_CTL_ES3)
323 #define CONTROL_DEFAULT_3 \
324  (CONTROL_DEFAULT_BASE | \
325  RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3)
326 
327 static void n2rng_control_swstate_init(struct n2rng *np)
328 {
329  int i;
330 
331  np->flags |= N2RNG_FLAG_CONTROL;
332 
333  np->health_check_sec = N2RNG_HEALTH_CHECK_SEC_DEFAULT;
334  np->accum_cycles = N2RNG_ACCUM_CYCLES_DEFAULT;
335  np->wd_timeo = N2RNG_WD_TIMEO_DEFAULT;
336 
337  for (i = 0; i < np->num_units; i++) {
338  struct n2rng_unit *up = &np->units[i];
339 
340  up->control[0] = CONTROL_DEFAULT_0;
341  up->control[1] = CONTROL_DEFAULT_1;
342  up->control[2] = CONTROL_DEFAULT_2;
343  up->control[3] = CONTROL_DEFAULT_3;
344  }
345 
346  np->hv_state = HV_RNG_STATE_UNCONFIGURED;
347 }
348 
349 static int n2rng_grab_diag_control(struct n2rng *np)
350 {
351  int i, busy_count, err = -ENODEV;
352 
353  busy_count = 0;
354  for (i = 0; i < 100; i++) {
355  err = n2rng_try_read_ctl(np);
356  if (err != -EAGAIN)
357  break;
358 
359  if (++busy_count > 100) {
360  dev_err(&np->op->dev,
361  "Grab diag control timeout.\n");
362  return -ENODEV;
363  }
364 
365  udelay(1);
366  }
367 
368  return err;
369 }
370 
371 static int n2rng_init_control(struct n2rng *np)
372 {
373  int err = n2rng_grab_diag_control(np);
374 
375  /* Not in the control domain, that's OK we are only a consumer
376  * of the RNG data, we don't setup and program it.
377  */
378  if (err == -EPERM)
379  return 0;
380  if (err)
381  return err;
382 
383  n2rng_control_swstate_init(np);
384 
385  return 0;
386 }
387 
388 static int n2rng_data_read(struct hwrng *rng, u32 *data)
389 {
390  struct n2rng *np = (struct n2rng *) rng->priv;
391  unsigned long ra = __pa(&np->test_data);
392  int len;
393 
394  if (!(np->flags & N2RNG_FLAG_READY)) {
395  len = 0;
396  } else if (np->flags & N2RNG_FLAG_BUFFER_VALID) {
397  np->flags &= ~N2RNG_FLAG_BUFFER_VALID;
398  *data = np->buffer;
399  len = 4;
400  } else {
401  int err = n2rng_generic_read_data(ra);
402  if (!err) {
403  np->buffer = np->test_data >> 32;
404  *data = np->test_data & 0xffffffff;
405  len = 4;
406  } else {
407  dev_err(&np->op->dev, "RNG error, restesting\n");
408  np->flags &= ~N2RNG_FLAG_READY;
409  if (!(np->flags & N2RNG_FLAG_SHUTDOWN))
410  schedule_delayed_work(&np->work, 0);
411  len = 0;
412  }
413  }
414 
415  return len;
416 }
417 
418 /* On a guest node, just make sure we can read random data properly.
419  * If a control node reboots or reloads it's n2rng driver, this won't
420  * work during that time. So we have to keep probing until the device
421  * becomes usable.
422  */
423 static int n2rng_guest_check(struct n2rng *np)
424 {
425  unsigned long ra = __pa(&np->test_data);
426 
427  return n2rng_generic_read_data(ra);
428 }
429 
430 static int n2rng_entropy_diag_read(struct n2rng *np, unsigned long unit,
431  u64 *pre_control, u64 pre_state,
432  u64 *buffer, unsigned long buf_len,
433  u64 *post_control, u64 post_state)
434 {
435  unsigned long post_ctl_ra = __pa(post_control);
436  unsigned long pre_ctl_ra = __pa(pre_control);
437  unsigned long buffer_ra = __pa(buffer);
438  int err;
439 
440  err = n2rng_generic_write_control(np, pre_ctl_ra, unit, pre_state);
441  if (err)
442  return err;
443 
444  err = n2rng_generic_read_diag_data(np, unit,
445  buffer_ra, buf_len);
446 
447  (void) n2rng_generic_write_control(np, post_ctl_ra, unit,
448  post_state);
449 
450  return err;
451 }
452 
453 static u64 advance_polynomial(u64 poly, u64 val, int count)
454 {
455  int i;
456 
457  for (i = 0; i < count; i++) {
458  int highbit_set = ((s64)val < 0);
459 
460  val <<= 1;
461  if (highbit_set)
462  val ^= poly;
463  }
464 
465  return val;
466 }
467 
468 static int n2rng_test_buffer_find(struct n2rng *np, u64 val)
469 {
470  int i, count = 0;
471 
472  /* Purposefully skip over the first word. */
473  for (i = 1; i < SELFTEST_BUFFER_WORDS; i++) {
474  if (np->test_buffer[i] == val)
475  count++;
476  }
477  return count;
478 }
479 
480 static void n2rng_dump_test_buffer(struct n2rng *np)
481 {
482  int i;
483 
484  for (i = 0; i < SELFTEST_BUFFER_WORDS; i++)
485  dev_err(&np->op->dev, "Test buffer slot %d [0x%016llx]\n",
486  i, np->test_buffer[i]);
487 }
488 
489 static int n2rng_check_selftest_buffer(struct n2rng *np, unsigned long unit)
490 {
491  u64 val = SELFTEST_VAL;
492  int err, matches, limit;
493 
494  matches = 0;
495  for (limit = 0; limit < SELFTEST_LOOPS_MAX; limit++) {
496  matches += n2rng_test_buffer_find(np, val);
497  if (matches >= SELFTEST_MATCH_GOAL)
498  break;
499  val = advance_polynomial(SELFTEST_POLY, val, 1);
500  }
501 
502  err = 0;
503  if (limit >= SELFTEST_LOOPS_MAX) {
504  err = -ENODEV;
505  dev_err(&np->op->dev, "Selftest failed on unit %lu\n", unit);
506  n2rng_dump_test_buffer(np);
507  } else
508  dev_info(&np->op->dev, "Selftest passed on unit %lu\n", unit);
509 
510  return err;
511 }
512 
513 static int n2rng_control_selftest(struct n2rng *np, unsigned long unit)
514 {
515  int err;
516 
517  np->test_control[0] = (0x2 << RNG_CTL_ASEL_SHIFT);
518  np->test_control[1] = (0x2 << RNG_CTL_ASEL_SHIFT);
519  np->test_control[2] = (0x2 << RNG_CTL_ASEL_SHIFT);
520  np->test_control[3] = ((0x2 << RNG_CTL_ASEL_SHIFT) |
521  RNG_CTL_LFSR |
522  ((SELFTEST_TICKS - 2) << RNG_CTL_WAIT_SHIFT));
523 
524 
525  err = n2rng_entropy_diag_read(np, unit, np->test_control,
526  HV_RNG_STATE_HEALTHCHECK,
527  np->test_buffer,
528  sizeof(np->test_buffer),
529  &np->units[unit].control[0],
530  np->hv_state);
531  if (err)
532  return err;
533 
534  return n2rng_check_selftest_buffer(np, unit);
535 }
536 
537 static int n2rng_control_check(struct n2rng *np)
538 {
539  int i;
540 
541  for (i = 0; i < np->num_units; i++) {
542  int err = n2rng_control_selftest(np, i);
543  if (err)
544  return err;
545  }
546  return 0;
547 }
548 
549 /* The sanity checks passed, install the final configuration into the
550  * chip, it's ready to use.
551  */
552 static int n2rng_control_configure_units(struct n2rng *np)
553 {
554  int unit, err;
555 
556  err = 0;
557  for (unit = 0; unit < np->num_units; unit++) {
558  struct n2rng_unit *up = &np->units[unit];
559  unsigned long ctl_ra = __pa(&up->control[0]);
560  int esrc;
561  u64 base;
562 
563  base = ((np->accum_cycles << RNG_CTL_WAIT_SHIFT) |
564  (2 << RNG_CTL_ASEL_SHIFT) |
565  RNG_CTL_LFSR);
566 
567  /* XXX This isn't the best. We should fetch a bunch
568  * XXX of words using each entropy source combined XXX
569  * with each VCO setting, and see which combinations
570  * XXX give the best random data.
571  */
572  for (esrc = 0; esrc < 3; esrc++)
573  up->control[esrc] = base |
574  (esrc << RNG_CTL_VCO_SHIFT) |
575  (RNG_CTL_ES1 << esrc);
576 
577  up->control[3] = base |
578  (RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3);
579 
580  err = n2rng_generic_write_control(np, ctl_ra, unit,
581  HV_RNG_STATE_CONFIGURED);
582  if (err)
583  break;
584  }
585 
586  return err;
587 }
588 
589 static void n2rng_work(struct work_struct *work)
590 {
591  struct n2rng *np = container_of(work, struct n2rng, work.work);
592  int err = 0;
593 
594  if (!(np->flags & N2RNG_FLAG_CONTROL)) {
595  err = n2rng_guest_check(np);
596  } else {
597  preempt_disable();
598  err = n2rng_control_check(np);
599  preempt_enable();
600 
601  if (!err)
602  err = n2rng_control_configure_units(np);
603  }
604 
605  if (!err) {
606  np->flags |= N2RNG_FLAG_READY;
607  dev_info(&np->op->dev, "RNG ready\n");
608  }
609 
610  if (err && !(np->flags & N2RNG_FLAG_SHUTDOWN))
611  schedule_delayed_work(&np->work, HZ * 2);
612 }
613 
614 static void __devinit n2rng_driver_version(void)
615 {
616  static int n2rng_version_printed;
617 
618  if (n2rng_version_printed++ == 0)
619  pr_info("%s", version);
620 }
621 
622 static const struct of_device_id n2rng_match[];
623 static int __devinit n2rng_probe(struct platform_device *op)
624 {
625  const struct of_device_id *match;
626  int multi_capable;
627  int err = -ENOMEM;
628  struct n2rng *np;
629 
630  match = of_match_device(n2rng_match, &op->dev);
631  if (!match)
632  return -EINVAL;
633  multi_capable = (match->data != NULL);
634 
635  n2rng_driver_version();
636  np = kzalloc(sizeof(*np), GFP_KERNEL);
637  if (!np)
638  goto out;
639  np->op = op;
640 
641  INIT_DELAYED_WORK(&np->work, n2rng_work);
642 
643  if (multi_capable)
644  np->flags |= N2RNG_FLAG_MULTI;
645 
646  err = -ENODEV;
647  np->hvapi_major = 2;
648  if (sun4v_hvapi_register(HV_GRP_RNG,
649  np->hvapi_major,
650  &np->hvapi_minor)) {
651  np->hvapi_major = 1;
652  if (sun4v_hvapi_register(HV_GRP_RNG,
653  np->hvapi_major,
654  &np->hvapi_minor)) {
655  dev_err(&op->dev, "Cannot register suitable "
656  "HVAPI version.\n");
657  goto out_free;
658  }
659  }
660 
661  if (np->flags & N2RNG_FLAG_MULTI) {
662  if (np->hvapi_major < 2) {
663  dev_err(&op->dev, "multi-unit-capable RNG requires "
664  "HVAPI major version 2 or later, got %lu\n",
665  np->hvapi_major);
666  goto out_hvapi_unregister;
667  }
668  np->num_units = of_getintprop_default(op->dev.of_node,
669  "rng-#units", 0);
670  if (!np->num_units) {
671  dev_err(&op->dev, "VF RNG lacks rng-#units property\n");
672  goto out_hvapi_unregister;
673  }
674  } else
675  np->num_units = 1;
676 
677  dev_info(&op->dev, "Registered RNG HVAPI major %lu minor %lu\n",
678  np->hvapi_major, np->hvapi_minor);
679 
680  np->units = kzalloc(sizeof(struct n2rng_unit) * np->num_units,
681  GFP_KERNEL);
682  err = -ENOMEM;
683  if (!np->units)
684  goto out_hvapi_unregister;
685 
686  err = n2rng_init_control(np);
687  if (err)
688  goto out_free_units;
689 
690  dev_info(&op->dev, "Found %s RNG, units: %d\n",
691  ((np->flags & N2RNG_FLAG_MULTI) ?
692  "multi-unit-capable" : "single-unit"),
693  np->num_units);
694 
695  np->hwrng.name = "n2rng";
696  np->hwrng.data_read = n2rng_data_read;
697  np->hwrng.priv = (unsigned long) np;
698 
699  err = hwrng_register(&np->hwrng);
700  if (err)
701  goto out_free_units;
702 
703  dev_set_drvdata(&op->dev, np);
704 
705  schedule_delayed_work(&np->work, 0);
706 
707  return 0;
708 
709 out_free_units:
710  kfree(np->units);
711  np->units = NULL;
712 
713 out_hvapi_unregister:
714  sun4v_hvapi_unregister(HV_GRP_RNG);
715 
716 out_free:
717  kfree(np);
718 out:
719  return err;
720 }
721 
722 static int __devexit n2rng_remove(struct platform_device *op)
723 {
724  struct n2rng *np = dev_get_drvdata(&op->dev);
725 
726  np->flags |= N2RNG_FLAG_SHUTDOWN;
727 
728  cancel_delayed_work_sync(&np->work);
729 
730  hwrng_unregister(&np->hwrng);
731 
732  sun4v_hvapi_unregister(HV_GRP_RNG);
733 
734  kfree(np->units);
735  np->units = NULL;
736 
737  kfree(np);
738 
739  dev_set_drvdata(&op->dev, NULL);
740 
741  return 0;
742 }
743 
744 static const struct of_device_id n2rng_match[] = {
745  {
746  .name = "random-number-generator",
747  .compatible = "SUNW,n2-rng",
748  },
749  {
750  .name = "random-number-generator",
751  .compatible = "SUNW,vf-rng",
752  .data = (void *) 1,
753  },
754  {
755  .name = "random-number-generator",
756  .compatible = "SUNW,kt-rng",
757  .data = (void *) 1,
758  },
759  {},
760 };
761 MODULE_DEVICE_TABLE(of, n2rng_match);
762 
763 static struct platform_driver n2rng_driver = {
764  .driver = {
765  .name = "n2rng",
766  .owner = THIS_MODULE,
767  .of_match_table = n2rng_match,
768  },
769  .probe = n2rng_probe,
770  .remove = __devexit_p(n2rng_remove),
771 };
772 
773 module_platform_driver(n2rng_driver);
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