1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2012 by Oracle Inc
4  * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
5  *
6  * This code borrows ideas from
7  * https://lore.kernel.org/lkml/1322673664-14642-6-git-send-email-konrad.wilk@oracle.com
8  * so many thanks go to Kevin Tian <kevin.tian@intel.com>
9  * and Yu Ke <ke.yu@intel.com>.
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/cpumask.h>
15 #include <linux/cpufreq.h>
16 #include <linux/freezer.h>
17 #include <linux/kernel.h>
18 #include <linux/kthread.h>
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/types.h>
22 #include <linux/syscore_ops.h>
23 #include <linux/acpi.h>
24 #include <acpi/processor.h>
25 #include <xen/xen.h>
26 #include <xen/interface/platform.h>
27 #include <asm/xen/hypercall.h>
28 
29 static int no_hypercall;
30 MODULE_PARM_DESC(off, "Inhibit the hypercall.");
31 module_param_named(off, no_hypercall, int, 0400);
32 
33 /*
34  * Note: Do not convert the acpi_id* below to cpumask_var_t or use cpumask_bit
35  * - as those shrink to nr_cpu_bits (which is dependent on possible_cpu), which
36  * can be less than what we want to put in. Instead use the 'nr_acpi_bits'
37  * which is dynamically computed based on the MADT or x2APIC table.
38  */
39 static unsigned int nr_acpi_bits;
40 /* Mutex to protect the acpi_ids_done - for CPU hotplug use. */
41 static DEFINE_MUTEX(acpi_ids_mutex);
42 /* Which ACPI ID we have processed from 'struct acpi_processor'. */
43 static unsigned long *acpi_ids_done;
44 /* Which ACPI ID exist in the SSDT/DSDT processor definitions. */
45 static unsigned long *acpi_id_present;
46 /* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
47 static unsigned long *acpi_id_cst_present;
48 /* Which ACPI P-State dependencies for a enumerated processor */
49 static struct acpi_psd_package *acpi_psd;
50 
51 static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
52 {
53 	struct xen_platform_op op = {
54 		.cmd			= XENPF_set_processor_pminfo,
55 		.interface_version	= XENPF_INTERFACE_VERSION,
56 		.u.set_pminfo.id	= _pr->acpi_id,
57 		.u.set_pminfo.type	= XEN_PM_CX,
58 	};
59 	struct xen_processor_cx *dst_cx, *dst_cx_states = NULL;
60 	struct acpi_processor_cx *cx;
61 	unsigned int i, ok;
62 	int ret = 0;
63 
64 	dst_cx_states = kcalloc(_pr->power.count,
65 				sizeof(struct xen_processor_cx), GFP_KERNEL);
66 	if (!dst_cx_states)
67 		return -ENOMEM;
68 
69 	for (ok = 0, i = 1; i <= _pr->power.count; i++) {
70 		cx = &_pr->power.states[i];
71 		if (!cx->valid)
72 			continue;
73 
74 		dst_cx = &(dst_cx_states[ok++]);
75 
76 		dst_cx->reg.space_id = ACPI_ADR_SPACE_SYSTEM_IO;
77 		if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
78 			dst_cx->reg.bit_width = 8;
79 			dst_cx->reg.bit_offset = 0;
80 			dst_cx->reg.access_size = 1;
81 		} else {
82 			dst_cx->reg.space_id = ACPI_ADR_SPACE_FIXED_HARDWARE;
83 			if (cx->entry_method == ACPI_CSTATE_FFH) {
84 				/* NATIVE_CSTATE_BEYOND_HALT */
85 				dst_cx->reg.bit_offset = 2;
86 				dst_cx->reg.bit_width = 1; /* VENDOR_INTEL */
87 			}
88 			dst_cx->reg.access_size = 0;
89 		}
90 		dst_cx->reg.address = cx->address;
91 
92 		dst_cx->type = cx->type;
93 		dst_cx->latency = cx->latency;
94 
95 		dst_cx->dpcnt = 0;
96 		set_xen_guest_handle(dst_cx->dp, NULL);
97 	}
98 	if (!ok) {
99 		pr_debug("No _Cx for ACPI CPU %u\n", _pr->acpi_id);
100 		kfree(dst_cx_states);
101 		return -EINVAL;
102 	}
103 	op.u.set_pminfo.power.count = ok;
104 	op.u.set_pminfo.power.flags.bm_control = _pr->flags.bm_control;
105 	op.u.set_pminfo.power.flags.bm_check = _pr->flags.bm_check;
106 	op.u.set_pminfo.power.flags.has_cst = _pr->flags.has_cst;
107 	op.u.set_pminfo.power.flags.power_setup_done =
108 		_pr->flags.power_setup_done;
109 
110 	set_xen_guest_handle(op.u.set_pminfo.power.states, dst_cx_states);
111 
112 	if (!no_hypercall)
113 		ret = HYPERVISOR_platform_op(&op);
114 
115 	if (!ret) {
116 		pr_debug("ACPI CPU%u - C-states uploaded.\n", _pr->acpi_id);
117 		for (i = 1; i <= _pr->power.count; i++) {
118 			cx = &_pr->power.states[i];
119 			if (!cx->valid)
120 				continue;
121 			pr_debug("     C%d: %s %d uS\n",
122 				 cx->type, cx->desc, (u32)cx->latency);
123 		}
124 	} else if ((ret != -EINVAL) && (ret != -ENOSYS))
125 		/* EINVAL means the ACPI ID is incorrect - meaning the ACPI
126 		 * table is referencing a non-existing CPU - which can happen
127 		 * with broken ACPI tables. */
128 		pr_err("(CX): Hypervisor error (%d) for ACPI CPU%u\n",
129 		       ret, _pr->acpi_id);
130 
131 	kfree(dst_cx_states);
132 
133 	return ret;
134 }
135 static struct xen_processor_px *
136 xen_copy_pss_data(struct acpi_processor *_pr,
137 		  struct xen_processor_performance *dst_perf)
138 {
139 	struct xen_processor_px *dst_states = NULL;
140 	unsigned int i;
141 
142 	BUILD_BUG_ON(sizeof(struct xen_processor_px) !=
143 		     sizeof(struct acpi_processor_px));
144 
145 	dst_states = kcalloc(_pr->performance->state_count,
146 			     sizeof(struct xen_processor_px), GFP_KERNEL);
147 	if (!dst_states)
148 		return ERR_PTR(-ENOMEM);
149 
150 	dst_perf->state_count = _pr->performance->state_count;
151 	for (i = 0; i < _pr->performance->state_count; i++) {
152 		/* Fortunatly for us, they are both the same size */
153 		memcpy(&(dst_states[i]), &(_pr->performance->states[i]),
154 		       sizeof(struct acpi_processor_px));
155 	}
156 	return dst_states;
157 }
158 static int xen_copy_psd_data(struct acpi_processor *_pr,
159 			     struct xen_processor_performance *dst)
160 {
161 	struct acpi_psd_package *pdomain;
162 
163 	BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
164 		     sizeof(struct acpi_psd_package));
165 
166 	/* This information is enumerated only if acpi_processor_preregister_performance
167 	 * has been called.
168 	 */
169 	dst->shared_type = _pr->performance->shared_type;
170 
171 	pdomain = &(_pr->performance->domain_info);
172 
173 	/* 'acpi_processor_preregister_performance' does not parse if the
174 	 * num_processors <= 1, but Xen still requires it. Do it manually here.
175 	 */
176 	if (pdomain->num_processors <= 1) {
177 		if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
178 			dst->shared_type = CPUFREQ_SHARED_TYPE_ALL;
179 		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
180 			dst->shared_type = CPUFREQ_SHARED_TYPE_HW;
181 		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
182 			dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;
183 
184 	}
185 	memcpy(&(dst->domain_info), pdomain, sizeof(struct acpi_psd_package));
186 	return 0;
187 }
188 static int xen_copy_pct_data(struct acpi_pct_register *pct,
189 			     struct xen_pct_register *dst_pct)
190 {
191 	/* It would be nice if you could just do 'memcpy(pct, dst_pct') but
192 	 * sadly the Xen structure did not have the proper padding so the
193 	 * descriptor field takes two (dst_pct) bytes instead of one (pct).
194 	 */
195 	dst_pct->descriptor = pct->descriptor;
196 	dst_pct->length = pct->length;
197 	dst_pct->space_id = pct->space_id;
198 	dst_pct->bit_width = pct->bit_width;
199 	dst_pct->bit_offset = pct->bit_offset;
200 	dst_pct->reserved = pct->reserved;
201 	dst_pct->address = pct->address;
202 	return 0;
203 }
204 static int push_pxx_to_hypervisor(struct acpi_processor *_pr)
205 {
206 	int ret = 0;
207 	struct xen_platform_op op = {
208 		.cmd			= XENPF_set_processor_pminfo,
209 		.interface_version	= XENPF_INTERFACE_VERSION,
210 		.u.set_pminfo.id	= _pr->acpi_id,
211 		.u.set_pminfo.type	= XEN_PM_PX,
212 	};
213 	struct xen_processor_performance *dst_perf;
214 	struct xen_processor_px *dst_states = NULL;
215 
216 	dst_perf = &op.u.set_pminfo.perf;
217 
218 	dst_perf->platform_limit = _pr->performance_platform_limit;
219 	dst_perf->flags |= XEN_PX_PPC;
220 	xen_copy_pct_data(&(_pr->performance->control_register),
221 			  &dst_perf->control_register);
222 	xen_copy_pct_data(&(_pr->performance->status_register),
223 			  &dst_perf->status_register);
224 	dst_perf->flags |= XEN_PX_PCT;
225 	dst_states = xen_copy_pss_data(_pr, dst_perf);
226 	if (!IS_ERR_OR_NULL(dst_states)) {
227 		set_xen_guest_handle(dst_perf->states, dst_states);
228 		dst_perf->flags |= XEN_PX_PSS;
229 	}
230 	if (!xen_copy_psd_data(_pr, dst_perf))
231 		dst_perf->flags |= XEN_PX_PSD;
232 
233 	if (dst_perf->flags != (XEN_PX_PSD | XEN_PX_PSS | XEN_PX_PCT | XEN_PX_PPC)) {
234 		pr_warn("ACPI CPU%u missing some P-state data (%x), skipping\n",
235 			_pr->acpi_id, dst_perf->flags);
236 		ret = -ENODEV;
237 		goto err_free;
238 	}
239 
240 	if (!no_hypercall)
241 		ret = HYPERVISOR_platform_op(&op);
242 
243 	if (!ret) {
244 		struct acpi_processor_performance *perf;
245 		unsigned int i;
246 
247 		perf = _pr->performance;
248 		pr_debug("ACPI CPU%u - P-states uploaded.\n", _pr->acpi_id);
249 		for (i = 0; i < perf->state_count; i++) {
250 			pr_debug("     %cP%d: %d MHz, %d mW, %d uS\n",
251 			(i == perf->state ? '*' : ' '), i,
252 			(u32) perf->states[i].core_frequency,
253 			(u32) perf->states[i].power,
254 			(u32) perf->states[i].transition_latency);
255 		}
256 	} else if ((ret != -EINVAL) && (ret != -ENOSYS))
257 		/* EINVAL means the ACPI ID is incorrect - meaning the ACPI
258 		 * table is referencing a non-existing CPU - which can happen
259 		 * with broken ACPI tables. */
260 		pr_warn("(_PXX): Hypervisor error (%d) for ACPI CPU%u\n",
261 			ret, _pr->acpi_id);
262 err_free:
263 	if (!IS_ERR_OR_NULL(dst_states))
264 		kfree(dst_states);
265 
266 	return ret;
267 }
268 static int upload_pm_data(struct acpi_processor *_pr)
269 {
270 	int err = 0;
271 
272 	mutex_lock(&acpi_ids_mutex);
273 	if (__test_and_set_bit(_pr->acpi_id, acpi_ids_done)) {
274 		mutex_unlock(&acpi_ids_mutex);
275 		return -EBUSY;
276 	}
277 	if (_pr->flags.power)
278 		err = push_cxx_to_hypervisor(_pr);
279 
280 	if (_pr->performance && _pr->performance->states)
281 		err |= push_pxx_to_hypervisor(_pr);
282 
283 	mutex_unlock(&acpi_ids_mutex);
284 	return err;
285 }
286 static unsigned int __init get_max_acpi_id(void)
287 {
288 	struct xenpf_pcpuinfo *info;
289 	struct xen_platform_op op = {
290 		.cmd = XENPF_get_cpuinfo,
291 		.interface_version = XENPF_INTERFACE_VERSION,
292 	};
293 	int ret = 0;
294 	unsigned int i, last_cpu, max_acpi_id = 0;
295 
296 	info = &op.u.pcpu_info;
297 	info->xen_cpuid = 0;
298 
299 	ret = HYPERVISOR_platform_op(&op);
300 	if (ret)
301 		return NR_CPUS;
302 
303 	/* The max_present is the same irregardless of the xen_cpuid */
304 	last_cpu = op.u.pcpu_info.max_present;
305 	for (i = 0; i <= last_cpu; i++) {
306 		info->xen_cpuid = i;
307 		ret = HYPERVISOR_platform_op(&op);
308 		if (ret)
309 			continue;
310 		max_acpi_id = max(info->acpi_id, max_acpi_id);
311 	}
312 	max_acpi_id *= 2; /* Slack for CPU hotplug support. */
313 	pr_debug("Max ACPI ID: %u\n", max_acpi_id);
314 	return max_acpi_id;
315 }
316 /*
317  * The read_acpi_id and check_acpi_ids are there to support the Xen
318  * oddity of virtual CPUs != physical CPUs in the initial domain.
319  * The user can supply 'xen_max_vcpus=X' on the Xen hypervisor line
320  * which will band the amount of CPUs the initial domain can see.
321  * In general that is OK, except it plays havoc with any of the
322  * for_each_[present|online]_cpu macros which are banded to the virtual
323  * CPU amount.
324  */
325 static acpi_status
326 read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
327 {
328 	u32 acpi_id;
329 	acpi_status status;
330 	acpi_object_type acpi_type;
331 	unsigned long long tmp;
332 	union acpi_object object = { 0 };
333 	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
334 	acpi_io_address pblk = 0;
335 
336 	status = acpi_get_type(handle, &acpi_type);
337 	if (ACPI_FAILURE(status))
338 		return AE_OK;
339 
340 	switch (acpi_type) {
341 	case ACPI_TYPE_PROCESSOR:
342 		status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
343 		if (ACPI_FAILURE(status))
344 			return AE_OK;
345 		acpi_id = object.processor.proc_id;
346 		pblk = object.processor.pblk_address;
347 		break;
348 	case ACPI_TYPE_DEVICE:
349 		status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
350 		if (ACPI_FAILURE(status))
351 			return AE_OK;
352 		acpi_id = tmp;
353 		break;
354 	default:
355 		return AE_OK;
356 	}
357 	if (invalid_phys_cpuid(acpi_get_phys_id(handle,
358 						acpi_type == ACPI_TYPE_DEVICE,
359 						acpi_id))) {
360 		pr_debug("CPU with ACPI ID %u is unavailable\n", acpi_id);
361 		return AE_OK;
362 	}
363 	/* There are more ACPI Processor objects than in x2APIC or MADT.
364 	 * This can happen with incorrect ACPI SSDT declerations. */
365 	if (acpi_id >= nr_acpi_bits) {
366 		pr_debug("max acpi id %u, trying to set %u\n",
367 			 nr_acpi_bits - 1, acpi_id);
368 		return AE_OK;
369 	}
370 	/* OK, There is a ACPI Processor object */
371 	__set_bit(acpi_id, acpi_id_present);
372 
373 	pr_debug("ACPI CPU%u w/ PBLK:0x%lx\n", acpi_id, (unsigned long)pblk);
374 
375 	/* It has P-state dependencies */
376 	if (!acpi_processor_get_psd(handle, &acpi_psd[acpi_id])) {
377 		pr_debug("ACPI CPU%u w/ PST:coord_type = %llu domain = %llu\n",
378 			 acpi_id, acpi_psd[acpi_id].coord_type,
379 			 acpi_psd[acpi_id].domain);
380 	}
381 
382 	status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
383 	if (ACPI_FAILURE(status)) {
384 		if (!pblk)
385 			return AE_OK;
386 	}
387 	/* .. and it has a C-state */
388 	__set_bit(acpi_id, acpi_id_cst_present);
389 
390 	return AE_OK;
391 }
392 static int check_acpi_ids(struct acpi_processor *pr_backup)
393 {
394 
395 	if (!pr_backup)
396 		return -ENODEV;
397 
398 	if (acpi_id_present && acpi_id_cst_present)
399 		/* OK, done this once .. skip to uploading */
400 		goto upload;
401 
402 	/* All online CPUs have been processed at this stage. Now verify
403 	 * whether in fact "online CPUs" == physical CPUs.
404 	 */
405 	acpi_id_present = bitmap_zalloc(nr_acpi_bits, GFP_KERNEL);
406 	if (!acpi_id_present)
407 		return -ENOMEM;
408 
409 	acpi_id_cst_present = bitmap_zalloc(nr_acpi_bits, GFP_KERNEL);
410 	if (!acpi_id_cst_present) {
411 		bitmap_free(acpi_id_present);
412 		return -ENOMEM;
413 	}
414 
415 	acpi_psd = kcalloc(nr_acpi_bits, sizeof(struct acpi_psd_package),
416 			   GFP_KERNEL);
417 	if (!acpi_psd) {
418 		bitmap_free(acpi_id_present);
419 		bitmap_free(acpi_id_cst_present);
420 		return -ENOMEM;
421 	}
422 
423 	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
424 			    ACPI_UINT32_MAX,
425 			    read_acpi_id, NULL, NULL, NULL);
426 	acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, read_acpi_id, NULL, NULL);
427 
428 upload:
429 	if (!bitmap_equal(acpi_id_present, acpi_ids_done, nr_acpi_bits)) {
430 		unsigned int i;
431 		for_each_set_bit(i, acpi_id_present, nr_acpi_bits) {
432 			pr_backup->acpi_id = i;
433 			/* Mask out C-states if there are no _CST or PBLK */
434 			pr_backup->flags.power = test_bit(i, acpi_id_cst_present);
435 			/* num_entries is non-zero if we evaluated _PSD */
436 			if (acpi_psd[i].num_entries) {
437 				memcpy(&pr_backup->performance->domain_info,
438 				       &acpi_psd[i],
439 				       sizeof(struct acpi_psd_package));
440 			}
441 			(void)upload_pm_data(pr_backup);
442 		}
443 	}
444 
445 	return 0;
446 }
447 
448 /* acpi_perf_data is a pointer to percpu data. */
449 static struct acpi_processor_performance __percpu *acpi_perf_data;
450 
451 static void free_acpi_perf_data(void)
452 {
453 	int i;
454 
455 	/* Freeing a NULL pointer is OK, and alloc_percpu zeroes. */
456 	for_each_possible_cpu(i)
457 		free_cpumask_var(per_cpu_ptr(acpi_perf_data, i)
458 				 ->shared_cpu_map);
459 	free_percpu(acpi_perf_data);
460 }
461 
462 static int xen_upload_processor_pm_data(void)
463 {
464 	struct acpi_processor *pr_backup = NULL;
465 	int i;
466 	int rc = 0;
467 
468 	pr_info("Uploading Xen processor PM info\n");
469 
470 	for_each_possible_cpu(i) {
471 		struct acpi_processor *_pr;
472 		_pr = per_cpu(processors, i /* APIC ID */);
473 		if (!_pr)
474 			continue;
475 
476 		if (!pr_backup)
477 			pr_backup = kmemdup(_pr, sizeof(*_pr), GFP_KERNEL);
478 		(void)upload_pm_data(_pr);
479 	}
480 
481 	rc = check_acpi_ids(pr_backup);
482 	kfree(pr_backup);
483 
484 	return rc;
485 }
486 
487 static void xen_acpi_processor_resume_worker(struct work_struct *dummy)
488 {
489 	int rc;
490 
491 	bitmap_zero(acpi_ids_done, nr_acpi_bits);
492 
493 	rc = xen_upload_processor_pm_data();
494 	if (rc != 0)
495 		pr_info("ACPI data upload failed, error = %d\n", rc);
496 }
497 
498 static void xen_acpi_processor_resume(void)
499 {
500 	static DECLARE_WORK(wq, xen_acpi_processor_resume_worker);
501 
502 	/*
503 	 * xen_upload_processor_pm_data() calls non-atomic code.
504 	 * However, the context for xen_acpi_processor_resume is syscore
505 	 * with only the boot CPU online and in an atomic context.
506 	 *
507 	 * So defer the upload for some point safer.
508 	 */
509 	schedule_work(&wq);
510 }
511 
512 static struct syscore_ops xap_syscore_ops = {
513 	.resume	= xen_acpi_processor_resume,
514 };
515 
516 static int __init xen_acpi_processor_init(void)
517 {
518 	int i;
519 	int rc;
520 
521 	if (!xen_initial_domain())
522 		return -ENODEV;
523 
524 	nr_acpi_bits = get_max_acpi_id() + 1;
525 	acpi_ids_done = bitmap_zalloc(nr_acpi_bits, GFP_KERNEL);
526 	if (!acpi_ids_done)
527 		return -ENOMEM;
528 
529 	acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
530 	if (!acpi_perf_data) {
531 		pr_debug("Memory allocation error for acpi_perf_data\n");
532 		bitmap_free(acpi_ids_done);
533 		return -ENOMEM;
534 	}
535 	for_each_possible_cpu(i) {
536 		if (!zalloc_cpumask_var_node(
537 			&per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
538 			GFP_KERNEL, cpu_to_node(i))) {
539 			rc = -ENOMEM;
540 			goto err_out;
541 		}
542 	}
543 
544 	/* Do initialization in ACPI core. It is OK to fail here. */
545 	(void)acpi_processor_preregister_performance(acpi_perf_data);
546 
547 	for_each_possible_cpu(i) {
548 		struct acpi_processor *pr;
549 		struct acpi_processor_performance *perf;
550 
551 		pr = per_cpu(processors, i);
552 		perf = per_cpu_ptr(acpi_perf_data, i);
553 		if (!pr)
554 			continue;
555 
556 		pr->performance = perf;
557 		rc = acpi_processor_get_performance_info(pr);
558 		if (rc)
559 			goto err_out;
560 	}
561 
562 	rc = xen_upload_processor_pm_data();
563 	if (rc)
564 		goto err_unregister;
565 
566 	register_syscore_ops(&xap_syscore_ops);
567 
568 	return 0;
569 err_unregister:
570 	for_each_possible_cpu(i)
571 		acpi_processor_unregister_performance(i);
572 
573 err_out:
574 	/* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
575 	free_acpi_perf_data();
576 	bitmap_free(acpi_ids_done);
577 	return rc;
578 }
579 static void __exit xen_acpi_processor_exit(void)
580 {
581 	int i;
582 
583 	unregister_syscore_ops(&xap_syscore_ops);
584 	bitmap_free(acpi_ids_done);
585 	bitmap_free(acpi_id_present);
586 	bitmap_free(acpi_id_cst_present);
587 	kfree(acpi_psd);
588 	for_each_possible_cpu(i)
589 		acpi_processor_unregister_performance(i);
590 
591 	free_acpi_perf_data();
592 }
593 
594 MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
595 MODULE_DESCRIPTION("Xen ACPI Processor P-states (and Cx) driver which uploads PM data to Xen hypervisor");
596 MODULE_LICENSE("GPL");
597 
598 /* We want to be loaded before the CPU freq scaling drivers are loaded.
599  * They are loaded in late_initcall. */
600 device_initcall(xen_acpi_processor_init);
601 module_exit(xen_acpi_processor_exit);
602