xref: /linux/arch/powerpc/kernel/sysfs.c (revision 2d6ffcca623a9a16df6cdfbe8250b7a5904a5f5e)
1 #include <linux/sysdev.h>
2 #include <linux/cpu.h>
3 #include <linux/smp.h>
4 #include <linux/percpu.h>
5 #include <linux/init.h>
6 #include <linux/sched.h>
7 #include <linux/module.h>
8 #include <linux/nodemask.h>
9 #include <linux/cpumask.h>
10 #include <linux/notifier.h>
11 
12 #include <asm/current.h>
13 #include <asm/processor.h>
14 #include <asm/cputable.h>
15 #include <asm/firmware.h>
16 #include <asm/hvcall.h>
17 #include <asm/prom.h>
18 #include <asm/paca.h>
19 #include <asm/lppaca.h>
20 #include <asm/machdep.h>
21 #include <asm/smp.h>
22 
23 static DEFINE_PER_CPU(struct cpu, cpu_devices);
24 
25 /* SMT stuff */
26 
27 #ifdef CONFIG_PPC_MULTIPLATFORM
28 /* Time in microseconds we delay before sleeping in the idle loop */
29 DEFINE_PER_CPU(unsigned long, smt_snooze_delay) = { 100 };
30 
31 static ssize_t store_smt_snooze_delay(struct sys_device *dev,
32 				      struct sysdev_attribute *attr,
33 				      const char *buf,
34 				      size_t count)
35 {
36 	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
37 	ssize_t ret;
38 	unsigned long snooze;
39 
40 	ret = sscanf(buf, "%lu", &snooze);
41 	if (ret != 1)
42 		return -EINVAL;
43 
44 	per_cpu(smt_snooze_delay, cpu->sysdev.id) = snooze;
45 
46 	return count;
47 }
48 
49 static ssize_t show_smt_snooze_delay(struct sys_device *dev,
50 				     struct sysdev_attribute *attr,
51 				     char *buf)
52 {
53 	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
54 
55 	return sprintf(buf, "%lu\n", per_cpu(smt_snooze_delay, cpu->sysdev.id));
56 }
57 
58 static SYSDEV_ATTR(smt_snooze_delay, 0644, show_smt_snooze_delay,
59 		   store_smt_snooze_delay);
60 
61 /* Only parse OF options if the matching cmdline option was not specified */
62 static int smt_snooze_cmdline;
63 
64 static int __init smt_setup(void)
65 {
66 	struct device_node *options;
67 	const unsigned int *val;
68 	unsigned int cpu;
69 
70 	if (!cpu_has_feature(CPU_FTR_SMT))
71 		return -ENODEV;
72 
73 	options = of_find_node_by_path("/options");
74 	if (!options)
75 		return -ENODEV;
76 
77 	val = of_get_property(options, "ibm,smt-snooze-delay", NULL);
78 	if (!smt_snooze_cmdline && val) {
79 		for_each_possible_cpu(cpu)
80 			per_cpu(smt_snooze_delay, cpu) = *val;
81 	}
82 
83 	of_node_put(options);
84 	return 0;
85 }
86 __initcall(smt_setup);
87 
88 static int __init setup_smt_snooze_delay(char *str)
89 {
90 	unsigned int cpu;
91 	int snooze;
92 
93 	if (!cpu_has_feature(CPU_FTR_SMT))
94 		return 1;
95 
96 	smt_snooze_cmdline = 1;
97 
98 	if (get_option(&str, &snooze)) {
99 		for_each_possible_cpu(cpu)
100 			per_cpu(smt_snooze_delay, cpu) = snooze;
101 	}
102 
103 	return 1;
104 }
105 __setup("smt-snooze-delay=", setup_smt_snooze_delay);
106 
107 #endif /* CONFIG_PPC_MULTIPLATFORM */
108 
109 /*
110  * Enabling PMCs will slow partition context switch times so we only do
111  * it the first time we write to the PMCs.
112  */
113 
114 static DEFINE_PER_CPU(char, pmcs_enabled);
115 
116 void ppc64_enable_pmcs(void)
117 {
118 	/* Only need to enable them once */
119 	if (__get_cpu_var(pmcs_enabled))
120 		return;
121 
122 	__get_cpu_var(pmcs_enabled) = 1;
123 
124 	if (ppc_md.enable_pmcs)
125 		ppc_md.enable_pmcs();
126 }
127 EXPORT_SYMBOL(ppc64_enable_pmcs);
128 
129 /* XXX convert to rusty's on_one_cpu */
130 static unsigned long run_on_cpu(unsigned long cpu,
131 			        unsigned long (*func)(unsigned long),
132 				unsigned long arg)
133 {
134 	cpumask_t old_affinity = current->cpus_allowed;
135 	unsigned long ret;
136 
137 	/* should return -EINVAL to userspace */
138 	if (set_cpus_allowed(current, cpumask_of_cpu(cpu)))
139 		return 0;
140 
141 	ret = func(arg);
142 
143 	set_cpus_allowed(current, old_affinity);
144 
145 	return ret;
146 }
147 
148 #define SYSFS_PMCSETUP(NAME, ADDRESS) \
149 static unsigned long read_##NAME(unsigned long junk) \
150 { \
151 	return mfspr(ADDRESS); \
152 } \
153 static unsigned long write_##NAME(unsigned long val) \
154 { \
155 	ppc64_enable_pmcs(); \
156 	mtspr(ADDRESS, val); \
157 	return 0; \
158 } \
159 static ssize_t show_##NAME(struct sys_device *dev, \
160 			struct sysdev_attribute *attr, \
161 			char *buf) \
162 { \
163 	struct cpu *cpu = container_of(dev, struct cpu, sysdev); \
164 	unsigned long val = run_on_cpu(cpu->sysdev.id, read_##NAME, 0); \
165 	return sprintf(buf, "%lx\n", val); \
166 } \
167 static ssize_t __used \
168 	store_##NAME(struct sys_device *dev, struct sysdev_attribute *attr, \
169 			const char *buf, size_t count) \
170 { \
171 	struct cpu *cpu = container_of(dev, struct cpu, sysdev); \
172 	unsigned long val; \
173 	int ret = sscanf(buf, "%lx", &val); \
174 	if (ret != 1) \
175 		return -EINVAL; \
176 	run_on_cpu(cpu->sysdev.id, write_##NAME, val); \
177 	return count; \
178 }
179 
180 
181 /* Let's define all possible registers, we'll only hook up the ones
182  * that are implemented on the current processor
183  */
184 
185 SYSFS_PMCSETUP(mmcr0, SPRN_MMCR0);
186 SYSFS_PMCSETUP(mmcr1, SPRN_MMCR1);
187 SYSFS_PMCSETUP(mmcra, SPRN_MMCRA);
188 SYSFS_PMCSETUP(pmc1, SPRN_PMC1);
189 SYSFS_PMCSETUP(pmc2, SPRN_PMC2);
190 SYSFS_PMCSETUP(pmc3, SPRN_PMC3);
191 SYSFS_PMCSETUP(pmc4, SPRN_PMC4);
192 SYSFS_PMCSETUP(pmc5, SPRN_PMC5);
193 SYSFS_PMCSETUP(pmc6, SPRN_PMC6);
194 SYSFS_PMCSETUP(pmc7, SPRN_PMC7);
195 SYSFS_PMCSETUP(pmc8, SPRN_PMC8);
196 SYSFS_PMCSETUP(purr, SPRN_PURR);
197 SYSFS_PMCSETUP(spurr, SPRN_SPURR);
198 SYSFS_PMCSETUP(dscr, SPRN_DSCR);
199 
200 SYSFS_PMCSETUP(pa6t_pmc0, SPRN_PA6T_PMC0);
201 SYSFS_PMCSETUP(pa6t_pmc1, SPRN_PA6T_PMC1);
202 SYSFS_PMCSETUP(pa6t_pmc2, SPRN_PA6T_PMC2);
203 SYSFS_PMCSETUP(pa6t_pmc3, SPRN_PA6T_PMC3);
204 SYSFS_PMCSETUP(pa6t_pmc4, SPRN_PA6T_PMC4);
205 SYSFS_PMCSETUP(pa6t_pmc5, SPRN_PA6T_PMC5);
206 
207 #ifdef CONFIG_DEBUG_KERNEL
208 SYSFS_PMCSETUP(hid0, SPRN_HID0);
209 SYSFS_PMCSETUP(hid1, SPRN_HID1);
210 SYSFS_PMCSETUP(hid4, SPRN_HID4);
211 SYSFS_PMCSETUP(hid5, SPRN_HID5);
212 SYSFS_PMCSETUP(ima0, SPRN_PA6T_IMA0);
213 SYSFS_PMCSETUP(ima1, SPRN_PA6T_IMA1);
214 SYSFS_PMCSETUP(ima2, SPRN_PA6T_IMA2);
215 SYSFS_PMCSETUP(ima3, SPRN_PA6T_IMA3);
216 SYSFS_PMCSETUP(ima4, SPRN_PA6T_IMA4);
217 SYSFS_PMCSETUP(ima5, SPRN_PA6T_IMA5);
218 SYSFS_PMCSETUP(ima6, SPRN_PA6T_IMA6);
219 SYSFS_PMCSETUP(ima7, SPRN_PA6T_IMA7);
220 SYSFS_PMCSETUP(ima8, SPRN_PA6T_IMA8);
221 SYSFS_PMCSETUP(ima9, SPRN_PA6T_IMA9);
222 SYSFS_PMCSETUP(imaat, SPRN_PA6T_IMAAT);
223 SYSFS_PMCSETUP(btcr, SPRN_PA6T_BTCR);
224 SYSFS_PMCSETUP(pccr, SPRN_PA6T_PCCR);
225 SYSFS_PMCSETUP(rpccr, SPRN_PA6T_RPCCR);
226 SYSFS_PMCSETUP(der, SPRN_PA6T_DER);
227 SYSFS_PMCSETUP(mer, SPRN_PA6T_MER);
228 SYSFS_PMCSETUP(ber, SPRN_PA6T_BER);
229 SYSFS_PMCSETUP(ier, SPRN_PA6T_IER);
230 SYSFS_PMCSETUP(sier, SPRN_PA6T_SIER);
231 SYSFS_PMCSETUP(siar, SPRN_PA6T_SIAR);
232 SYSFS_PMCSETUP(tsr0, SPRN_PA6T_TSR0);
233 SYSFS_PMCSETUP(tsr1, SPRN_PA6T_TSR1);
234 SYSFS_PMCSETUP(tsr2, SPRN_PA6T_TSR2);
235 SYSFS_PMCSETUP(tsr3, SPRN_PA6T_TSR3);
236 #endif /* CONFIG_DEBUG_KERNEL */
237 
238 static SYSDEV_ATTR(mmcra, 0600, show_mmcra, store_mmcra);
239 static SYSDEV_ATTR(spurr, 0600, show_spurr, NULL);
240 static SYSDEV_ATTR(dscr, 0600, show_dscr, store_dscr);
241 static SYSDEV_ATTR(purr, 0600, show_purr, store_purr);
242 
243 static struct sysdev_attribute ibm_common_attrs[] = {
244 	_SYSDEV_ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
245 	_SYSDEV_ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
246 };
247 
248 static struct sysdev_attribute ibm_pmc_attrs[] = {
249 	_SYSDEV_ATTR(pmc1, 0600, show_pmc1, store_pmc1),
250 	_SYSDEV_ATTR(pmc2, 0600, show_pmc2, store_pmc2),
251 	_SYSDEV_ATTR(pmc3, 0600, show_pmc3, store_pmc3),
252 	_SYSDEV_ATTR(pmc4, 0600, show_pmc4, store_pmc4),
253 	_SYSDEV_ATTR(pmc5, 0600, show_pmc5, store_pmc5),
254 	_SYSDEV_ATTR(pmc6, 0600, show_pmc6, store_pmc6),
255 	_SYSDEV_ATTR(pmc7, 0600, show_pmc7, store_pmc7),
256 	_SYSDEV_ATTR(pmc8, 0600, show_pmc8, store_pmc8),
257 };
258 
259 static struct sysdev_attribute pa6t_attrs[] = {
260 	_SYSDEV_ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
261 	_SYSDEV_ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
262 	_SYSDEV_ATTR(pmc0, 0600, show_pa6t_pmc0, store_pa6t_pmc0),
263 	_SYSDEV_ATTR(pmc1, 0600, show_pa6t_pmc1, store_pa6t_pmc1),
264 	_SYSDEV_ATTR(pmc2, 0600, show_pa6t_pmc2, store_pa6t_pmc2),
265 	_SYSDEV_ATTR(pmc3, 0600, show_pa6t_pmc3, store_pa6t_pmc3),
266 	_SYSDEV_ATTR(pmc4, 0600, show_pa6t_pmc4, store_pa6t_pmc4),
267 	_SYSDEV_ATTR(pmc5, 0600, show_pa6t_pmc5, store_pa6t_pmc5),
268 #ifdef CONFIG_DEBUG_KERNEL
269 	_SYSDEV_ATTR(hid0, 0600, show_hid0, store_hid0),
270 	_SYSDEV_ATTR(hid1, 0600, show_hid1, store_hid1),
271 	_SYSDEV_ATTR(hid4, 0600, show_hid4, store_hid4),
272 	_SYSDEV_ATTR(hid5, 0600, show_hid5, store_hid5),
273 	_SYSDEV_ATTR(ima0, 0600, show_ima0, store_ima0),
274 	_SYSDEV_ATTR(ima1, 0600, show_ima1, store_ima1),
275 	_SYSDEV_ATTR(ima2, 0600, show_ima2, store_ima2),
276 	_SYSDEV_ATTR(ima3, 0600, show_ima3, store_ima3),
277 	_SYSDEV_ATTR(ima4, 0600, show_ima4, store_ima4),
278 	_SYSDEV_ATTR(ima5, 0600, show_ima5, store_ima5),
279 	_SYSDEV_ATTR(ima6, 0600, show_ima6, store_ima6),
280 	_SYSDEV_ATTR(ima7, 0600, show_ima7, store_ima7),
281 	_SYSDEV_ATTR(ima8, 0600, show_ima8, store_ima8),
282 	_SYSDEV_ATTR(ima9, 0600, show_ima9, store_ima9),
283 	_SYSDEV_ATTR(imaat, 0600, show_imaat, store_imaat),
284 	_SYSDEV_ATTR(btcr, 0600, show_btcr, store_btcr),
285 	_SYSDEV_ATTR(pccr, 0600, show_pccr, store_pccr),
286 	_SYSDEV_ATTR(rpccr, 0600, show_rpccr, store_rpccr),
287 	_SYSDEV_ATTR(der, 0600, show_der, store_der),
288 	_SYSDEV_ATTR(mer, 0600, show_mer, store_mer),
289 	_SYSDEV_ATTR(ber, 0600, show_ber, store_ber),
290 	_SYSDEV_ATTR(ier, 0600, show_ier, store_ier),
291 	_SYSDEV_ATTR(sier, 0600, show_sier, store_sier),
292 	_SYSDEV_ATTR(siar, 0600, show_siar, store_siar),
293 	_SYSDEV_ATTR(tsr0, 0600, show_tsr0, store_tsr0),
294 	_SYSDEV_ATTR(tsr1, 0600, show_tsr1, store_tsr1),
295 	_SYSDEV_ATTR(tsr2, 0600, show_tsr2, store_tsr2),
296 	_SYSDEV_ATTR(tsr3, 0600, show_tsr3, store_tsr3),
297 #endif /* CONFIG_DEBUG_KERNEL */
298 };
299 
300 
301 static void register_cpu_online(unsigned int cpu)
302 {
303 	struct cpu *c = &per_cpu(cpu_devices, cpu);
304 	struct sys_device *s = &c->sysdev;
305 	struct sysdev_attribute *attrs, *pmc_attrs;
306 	int i, nattrs;
307 
308 	if (!firmware_has_feature(FW_FEATURE_ISERIES) &&
309 			cpu_has_feature(CPU_FTR_SMT))
310 		sysdev_create_file(s, &attr_smt_snooze_delay);
311 
312 	/* PMC stuff */
313 	switch (cur_cpu_spec->pmc_type) {
314 	case PPC_PMC_IBM:
315 		attrs = ibm_common_attrs;
316 		nattrs = sizeof(ibm_common_attrs) / sizeof(struct sysdev_attribute);
317 		pmc_attrs = ibm_pmc_attrs;
318 		break;
319 	case PPC_PMC_PA6T:
320 		/* PA Semi starts counting at PMC0 */
321 		attrs = pa6t_attrs;
322 		nattrs = sizeof(pa6t_attrs) / sizeof(struct sysdev_attribute);
323 		pmc_attrs = NULL;
324 		break;
325 	default:
326 		attrs = NULL;
327 		nattrs = 0;
328 		pmc_attrs = NULL;
329 	}
330 
331 	for (i = 0; i < nattrs; i++)
332 		sysdev_create_file(s, &attrs[i]);
333 
334 	if (pmc_attrs)
335 		for (i = 0; i < cur_cpu_spec->num_pmcs; i++)
336 			sysdev_create_file(s, &pmc_attrs[i]);
337 
338 	if (cpu_has_feature(CPU_FTR_MMCRA))
339 		sysdev_create_file(s, &attr_mmcra);
340 
341 	if (cpu_has_feature(CPU_FTR_PURR))
342 		sysdev_create_file(s, &attr_purr);
343 
344 	if (cpu_has_feature(CPU_FTR_SPURR))
345 		sysdev_create_file(s, &attr_spurr);
346 
347 	if (cpu_has_feature(CPU_FTR_DSCR))
348 		sysdev_create_file(s, &attr_dscr);
349 }
350 
351 #ifdef CONFIG_HOTPLUG_CPU
352 static void unregister_cpu_online(unsigned int cpu)
353 {
354 	struct cpu *c = &per_cpu(cpu_devices, cpu);
355 	struct sys_device *s = &c->sysdev;
356 	struct sysdev_attribute *attrs, *pmc_attrs;
357 	int i, nattrs;
358 
359 	BUG_ON(!c->hotpluggable);
360 
361 	if (!firmware_has_feature(FW_FEATURE_ISERIES) &&
362 			cpu_has_feature(CPU_FTR_SMT))
363 		sysdev_remove_file(s, &attr_smt_snooze_delay);
364 
365 	/* PMC stuff */
366 	switch (cur_cpu_spec->pmc_type) {
367 	case PPC_PMC_IBM:
368 		attrs = ibm_common_attrs;
369 		nattrs = sizeof(ibm_common_attrs) / sizeof(struct sysdev_attribute);
370 		pmc_attrs = ibm_pmc_attrs;
371 		break;
372 	case PPC_PMC_PA6T:
373 		/* PA Semi starts counting at PMC0 */
374 		attrs = pa6t_attrs;
375 		nattrs = sizeof(pa6t_attrs) / sizeof(struct sysdev_attribute);
376 		pmc_attrs = NULL;
377 		break;
378 	default:
379 		attrs = NULL;
380 		nattrs = 0;
381 		pmc_attrs = NULL;
382 	}
383 
384 	for (i = 0; i < nattrs; i++)
385 		sysdev_remove_file(s, &attrs[i]);
386 
387 	if (pmc_attrs)
388 		for (i = 0; i < cur_cpu_spec->num_pmcs; i++)
389 			sysdev_remove_file(s, &pmc_attrs[i]);
390 
391 	if (cpu_has_feature(CPU_FTR_MMCRA))
392 		sysdev_remove_file(s, &attr_mmcra);
393 
394 	if (cpu_has_feature(CPU_FTR_PURR))
395 		sysdev_remove_file(s, &attr_purr);
396 
397 	if (cpu_has_feature(CPU_FTR_SPURR))
398 		sysdev_remove_file(s, &attr_spurr);
399 
400 	if (cpu_has_feature(CPU_FTR_DSCR))
401 		sysdev_remove_file(s, &attr_dscr);
402 }
403 #endif /* CONFIG_HOTPLUG_CPU */
404 
405 static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,
406 				      unsigned long action, void *hcpu)
407 {
408 	unsigned int cpu = (unsigned int)(long)hcpu;
409 
410 	switch (action) {
411 	case CPU_ONLINE:
412 	case CPU_ONLINE_FROZEN:
413 		register_cpu_online(cpu);
414 		break;
415 #ifdef CONFIG_HOTPLUG_CPU
416 	case CPU_DEAD:
417 	case CPU_DEAD_FROZEN:
418 		unregister_cpu_online(cpu);
419 		break;
420 #endif
421 	}
422 	return NOTIFY_OK;
423 }
424 
425 static struct notifier_block __cpuinitdata sysfs_cpu_nb = {
426 	.notifier_call	= sysfs_cpu_notify,
427 };
428 
429 static DEFINE_MUTEX(cpu_mutex);
430 
431 int cpu_add_sysdev_attr(struct sysdev_attribute *attr)
432 {
433 	int cpu;
434 
435 	mutex_lock(&cpu_mutex);
436 
437 	for_each_possible_cpu(cpu) {
438 		sysdev_create_file(get_cpu_sysdev(cpu), attr);
439 	}
440 
441 	mutex_unlock(&cpu_mutex);
442 	return 0;
443 }
444 EXPORT_SYMBOL_GPL(cpu_add_sysdev_attr);
445 
446 int cpu_add_sysdev_attr_group(struct attribute_group *attrs)
447 {
448 	int cpu;
449 	struct sys_device *sysdev;
450 	int ret;
451 
452 	mutex_lock(&cpu_mutex);
453 
454 	for_each_possible_cpu(cpu) {
455 		sysdev = get_cpu_sysdev(cpu);
456 		ret = sysfs_create_group(&sysdev->kobj, attrs);
457 		WARN_ON(ret != 0);
458 	}
459 
460 	mutex_unlock(&cpu_mutex);
461 	return 0;
462 }
463 EXPORT_SYMBOL_GPL(cpu_add_sysdev_attr_group);
464 
465 
466 void cpu_remove_sysdev_attr(struct sysdev_attribute *attr)
467 {
468 	int cpu;
469 
470 	mutex_lock(&cpu_mutex);
471 
472 	for_each_possible_cpu(cpu) {
473 		sysdev_remove_file(get_cpu_sysdev(cpu), attr);
474 	}
475 
476 	mutex_unlock(&cpu_mutex);
477 }
478 EXPORT_SYMBOL_GPL(cpu_remove_sysdev_attr);
479 
480 void cpu_remove_sysdev_attr_group(struct attribute_group *attrs)
481 {
482 	int cpu;
483 	struct sys_device *sysdev;
484 
485 	mutex_lock(&cpu_mutex);
486 
487 	for_each_possible_cpu(cpu) {
488 		sysdev = get_cpu_sysdev(cpu);
489 		sysfs_remove_group(&sysdev->kobj, attrs);
490 	}
491 
492 	mutex_unlock(&cpu_mutex);
493 }
494 EXPORT_SYMBOL_GPL(cpu_remove_sysdev_attr_group);
495 
496 
497 /* NUMA stuff */
498 
499 #ifdef CONFIG_NUMA
500 static void register_nodes(void)
501 {
502 	int i;
503 
504 	for (i = 0; i < MAX_NUMNODES; i++)
505 		register_one_node(i);
506 }
507 
508 int sysfs_add_device_to_node(struct sys_device *dev, int nid)
509 {
510 	struct node *node = &node_devices[nid];
511 	return sysfs_create_link(&node->sysdev.kobj, &dev->kobj,
512 			kobject_name(&dev->kobj));
513 }
514 EXPORT_SYMBOL_GPL(sysfs_add_device_to_node);
515 
516 void sysfs_remove_device_from_node(struct sys_device *dev, int nid)
517 {
518 	struct node *node = &node_devices[nid];
519 	sysfs_remove_link(&node->sysdev.kobj, kobject_name(&dev->kobj));
520 }
521 EXPORT_SYMBOL_GPL(sysfs_remove_device_from_node);
522 
523 #else
524 static void register_nodes(void)
525 {
526 	return;
527 }
528 
529 #endif
530 
531 /* Only valid if CPU is present. */
532 static ssize_t show_physical_id(struct sys_device *dev, char *buf)
533 {
534 	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
535 
536 	return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->sysdev.id));
537 }
538 static SYSDEV_ATTR(physical_id, 0444, show_physical_id, NULL);
539 
540 static int __init topology_init(void)
541 {
542 	int cpu;
543 
544 	register_nodes();
545 	register_cpu_notifier(&sysfs_cpu_nb);
546 
547 	for_each_possible_cpu(cpu) {
548 		struct cpu *c = &per_cpu(cpu_devices, cpu);
549 
550 		/*
551 		 * For now, we just see if the system supports making
552 		 * the RTAS calls for CPU hotplug.  But, there may be a
553 		 * more comprehensive way to do this for an individual
554 		 * CPU.  For instance, the boot cpu might never be valid
555 		 * for hotplugging.
556 		 */
557 		if (ppc_md.cpu_die)
558 			c->hotpluggable = 1;
559 
560 		if (cpu_online(cpu) || c->hotpluggable) {
561 			register_cpu(c, cpu);
562 
563 			sysdev_create_file(&c->sysdev, &attr_physical_id);
564 		}
565 
566 		if (cpu_online(cpu))
567 			register_cpu_online(cpu);
568 	}
569 
570 	return 0;
571 }
572 subsys_initcall(topology_init);
573