Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas...
[linux-2.6.git] / drivers / char / hw_random / n2-drv.c
1 /* n2-drv.c: Niagara-2 RNG driver.
2  *
3  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
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      "0.1"
26 #define DRV_MODULE_RELDATE      "May 15, 2008"
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 (davem@davemloft.net)");
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 victoria_falls;
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         victoria_falls = (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 (victoria_falls)
644                 np->flags |= N2RNG_FLAG_VF;
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_VF) {
662                 if (np->hvapi_major < 2) {
663                         dev_err(&op->dev, "VF RNG requires HVAPI major "
664                                 "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_VF) ?
692                   "Victoria Falls" : "Niagara2"),
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 };
756 MODULE_DEVICE_TABLE(of, n2rng_match);
757
758 static struct platform_driver n2rng_driver = {
759         .driver = {
760                 .name = "n2rng",
761                 .owner = THIS_MODULE,
762                 .of_match_table = n2rng_match,
763         },
764         .probe          = n2rng_probe,
765         .remove         = __devexit_p(n2rng_remove),
766 };
767
768 static int __init n2rng_init(void)
769 {
770         return platform_driver_register(&n2rng_driver);
771 }
772
773 static void __exit n2rng_exit(void)
774 {
775         platform_driver_unregister(&n2rng_driver);
776 }
777
778 module_init(n2rng_init);
779 module_exit(n2rng_exit);