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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * acpi_pad.c ACPI Processor Aggregator Driver
4 *
5 * Copyright (c) 2009, Intel Corporation.
6 */
7
8#include <linux/kernel.h>
9#include <linux/cpumask.h>
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/types.h>
13#include <linux/kthread.h>
14#include <uapi/linux/sched/types.h>
15#include <linux/freezer.h>
16#include <linux/cpu.h>
17#include <linux/tick.h>
18#include <linux/slab.h>
19#include <linux/acpi.h>
20#include <asm/mwait.h>
21#include <xen/xen.h>
22
23#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
24#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
25#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
26static DEFINE_MUTEX(isolated_cpus_lock);
27static DEFINE_MUTEX(round_robin_lock);
28
29static unsigned long power_saving_mwait_eax;
30
31static unsigned char tsc_detected_unstable;
32static unsigned char tsc_marked_unstable;
33
34static void power_saving_mwait_init(void)
35{
36 unsigned int eax, ebx, ecx, edx;
37 unsigned int highest_cstate = 0;
38 unsigned int highest_subcstate = 0;
39 int i;
40
41 if (!boot_cpu_has(X86_FEATURE_MWAIT))
42 return;
43 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
44 return;
45
46 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
47
48 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
49 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
50 return;
51
52 edx >>= MWAIT_SUBSTATE_SIZE;
53 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
54 if (edx & MWAIT_SUBSTATE_MASK) {
55 highest_cstate = i;
56 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
57 }
58 }
59 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
60 (highest_subcstate - 1);
61
62#if defined(CONFIG_X86)
63 switch (boot_cpu_data.x86_vendor) {
64 case X86_VENDOR_HYGON:
65 case X86_VENDOR_AMD:
66 case X86_VENDOR_INTEL:
67 case X86_VENDOR_ZHAOXIN:
68 /*
69 * AMD Fam10h TSC will tick in all
70 * C/P/S0/S1 states when this bit is set.
71 */
72 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
73 tsc_detected_unstable = 1;
74 break;
75 default:
76 /* TSC could halt in idle */
77 tsc_detected_unstable = 1;
78 }
79#endif
80}
81
82static unsigned long cpu_weight[NR_CPUS];
83static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
84static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
85static void round_robin_cpu(unsigned int tsk_index)
86{
87 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
88 cpumask_var_t tmp;
89 int cpu;
90 unsigned long min_weight = -1;
91 unsigned long preferred_cpu;
92
93 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
94 return;
95
96 mutex_lock(&round_robin_lock);
97 cpumask_clear(tmp);
98 for_each_cpu(cpu, pad_busy_cpus)
99 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
100 cpumask_andnot(tmp, cpu_online_mask, tmp);
101 /* avoid HT sibilings if possible */
102 if (cpumask_empty(tmp))
103 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
104 if (cpumask_empty(tmp)) {
105 mutex_unlock(&round_robin_lock);
106 free_cpumask_var(tmp);
107 return;
108 }
109 for_each_cpu(cpu, tmp) {
110 if (cpu_weight[cpu] < min_weight) {
111 min_weight = cpu_weight[cpu];
112 preferred_cpu = cpu;
113 }
114 }
115
116 if (tsk_in_cpu[tsk_index] != -1)
117 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
118 tsk_in_cpu[tsk_index] = preferred_cpu;
119 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
120 cpu_weight[preferred_cpu]++;
121 mutex_unlock(&round_robin_lock);
122
123 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
124
125 free_cpumask_var(tmp);
126}
127
128static void exit_round_robin(unsigned int tsk_index)
129{
130 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
131 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
132 tsk_in_cpu[tsk_index] = -1;
133}
134
135static unsigned int idle_pct = 5; /* percentage */
136static unsigned int round_robin_time = 1; /* second */
137static int power_saving_thread(void *data)
138{
139 int do_sleep;
140 unsigned int tsk_index = (unsigned long)data;
141 u64 last_jiffies = 0;
142
143 sched_set_fifo_low(current);
144
145 while (!kthread_should_stop()) {
146 unsigned long expire_time;
147
148 /* round robin to cpus */
149 expire_time = last_jiffies + round_robin_time * HZ;
150 if (time_before(expire_time, jiffies)) {
151 last_jiffies = jiffies;
152 round_robin_cpu(tsk_index);
153 }
154
155 do_sleep = 0;
156
157 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
158
159 while (!need_resched()) {
160 if (tsc_detected_unstable && !tsc_marked_unstable) {
161 /* TSC could halt in idle, so notify users */
162 mark_tsc_unstable("TSC halts in idle");
163 tsc_marked_unstable = 1;
164 }
165 local_irq_disable();
166 tick_broadcast_enable();
167 tick_broadcast_enter();
168 stop_critical_timings();
169
170 mwait_idle_with_hints(power_saving_mwait_eax, 1);
171
172 start_critical_timings();
173 tick_broadcast_exit();
174 local_irq_enable();
175
176 if (time_before(expire_time, jiffies)) {
177 do_sleep = 1;
178 break;
179 }
180 }
181
182 /*
183 * current sched_rt has threshold for rt task running time.
184 * When a rt task uses 95% CPU time, the rt thread will be
185 * scheduled out for 5% CPU time to not starve other tasks. But
186 * the mechanism only works when all CPUs have RT task running,
187 * as if one CPU hasn't RT task, RT task from other CPUs will
188 * borrow CPU time from this CPU and cause RT task use > 95%
189 * CPU time. To make 'avoid starvation' work, takes a nap here.
190 */
191 if (unlikely(do_sleep))
192 schedule_timeout_killable(HZ * idle_pct / 100);
193
194 /* If an external event has set the need_resched flag, then
195 * we need to deal with it, or this loop will continue to
196 * spin without calling __mwait().
197 */
198 if (unlikely(need_resched()))
199 schedule();
200 }
201
202 exit_round_robin(tsk_index);
203 return 0;
204}
205
206static struct task_struct *ps_tsks[NR_CPUS];
207static unsigned int ps_tsk_num;
208static int create_power_saving_task(void)
209{
210 int rc;
211
212 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
213 (void *)(unsigned long)ps_tsk_num,
214 "acpi_pad/%d", ps_tsk_num);
215
216 if (IS_ERR(ps_tsks[ps_tsk_num])) {
217 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
218 ps_tsks[ps_tsk_num] = NULL;
219 } else {
220 rc = 0;
221 ps_tsk_num++;
222 }
223
224 return rc;
225}
226
227static void destroy_power_saving_task(void)
228{
229 if (ps_tsk_num > 0) {
230 ps_tsk_num--;
231 kthread_stop(ps_tsks[ps_tsk_num]);
232 ps_tsks[ps_tsk_num] = NULL;
233 }
234}
235
236static void set_power_saving_task_num(unsigned int num)
237{
238 if (num > ps_tsk_num) {
239 while (ps_tsk_num < num) {
240 if (create_power_saving_task())
241 return;
242 }
243 } else if (num < ps_tsk_num) {
244 while (ps_tsk_num > num)
245 destroy_power_saving_task();
246 }
247}
248
249static void acpi_pad_idle_cpus(unsigned int num_cpus)
250{
251 get_online_cpus();
252
253 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
254 set_power_saving_task_num(num_cpus);
255
256 put_online_cpus();
257}
258
259static uint32_t acpi_pad_idle_cpus_num(void)
260{
261 return ps_tsk_num;
262}
263
264static ssize_t acpi_pad_rrtime_store(struct device *dev,
265 struct device_attribute *attr, const char *buf, size_t count)
266{
267 unsigned long num;
268 if (kstrtoul(buf, 0, &num))
269 return -EINVAL;
270 if (num < 1 || num >= 100)
271 return -EINVAL;
272 mutex_lock(&isolated_cpus_lock);
273 round_robin_time = num;
274 mutex_unlock(&isolated_cpus_lock);
275 return count;
276}
277
278static ssize_t acpi_pad_rrtime_show(struct device *dev,
279 struct device_attribute *attr, char *buf)
280{
281 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
282}
283static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
284 acpi_pad_rrtime_show,
285 acpi_pad_rrtime_store);
286
287static ssize_t acpi_pad_idlepct_store(struct device *dev,
288 struct device_attribute *attr, const char *buf, size_t count)
289{
290 unsigned long num;
291 if (kstrtoul(buf, 0, &num))
292 return -EINVAL;
293 if (num < 1 || num >= 100)
294 return -EINVAL;
295 mutex_lock(&isolated_cpus_lock);
296 idle_pct = num;
297 mutex_unlock(&isolated_cpus_lock);
298 return count;
299}
300
301static ssize_t acpi_pad_idlepct_show(struct device *dev,
302 struct device_attribute *attr, char *buf)
303{
304 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
305}
306static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
307 acpi_pad_idlepct_show,
308 acpi_pad_idlepct_store);
309
310static ssize_t acpi_pad_idlecpus_store(struct device *dev,
311 struct device_attribute *attr, const char *buf, size_t count)
312{
313 unsigned long num;
314 if (kstrtoul(buf, 0, &num))
315 return -EINVAL;
316 mutex_lock(&isolated_cpus_lock);
317 acpi_pad_idle_cpus(num);
318 mutex_unlock(&isolated_cpus_lock);
319 return count;
320}
321
322static ssize_t acpi_pad_idlecpus_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
324{
325 return cpumap_print_to_pagebuf(false, buf,
326 to_cpumask(pad_busy_cpus_bits));
327}
328
329static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
330 acpi_pad_idlecpus_show,
331 acpi_pad_idlecpus_store);
332
333static int acpi_pad_add_sysfs(struct acpi_device *device)
334{
335 int result;
336
337 result = device_create_file(&device->dev, &dev_attr_idlecpus);
338 if (result)
339 return -ENODEV;
340 result = device_create_file(&device->dev, &dev_attr_idlepct);
341 if (result) {
342 device_remove_file(&device->dev, &dev_attr_idlecpus);
343 return -ENODEV;
344 }
345 result = device_create_file(&device->dev, &dev_attr_rrtime);
346 if (result) {
347 device_remove_file(&device->dev, &dev_attr_idlecpus);
348 device_remove_file(&device->dev, &dev_attr_idlepct);
349 return -ENODEV;
350 }
351 return 0;
352}
353
354static void acpi_pad_remove_sysfs(struct acpi_device *device)
355{
356 device_remove_file(&device->dev, &dev_attr_idlecpus);
357 device_remove_file(&device->dev, &dev_attr_idlepct);
358 device_remove_file(&device->dev, &dev_attr_rrtime);
359}
360
361/*
362 * Query firmware how many CPUs should be idle
363 * return -1 on failure
364 */
365static int acpi_pad_pur(acpi_handle handle)
366{
367 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
368 union acpi_object *package;
369 int num = -1;
370
371 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
372 return num;
373
374 if (!buffer.length || !buffer.pointer)
375 return num;
376
377 package = buffer.pointer;
378
379 if (package->type == ACPI_TYPE_PACKAGE &&
380 package->package.count == 2 &&
381 package->package.elements[0].integer.value == 1) /* rev 1 */
382
383 num = package->package.elements[1].integer.value;
384
385 kfree(buffer.pointer);
386 return num;
387}
388
389static void acpi_pad_handle_notify(acpi_handle handle)
390{
391 int num_cpus;
392 uint32_t idle_cpus;
393 struct acpi_buffer param = {
394 .length = 4,
395 .pointer = (void *)&idle_cpus,
396 };
397
398 mutex_lock(&isolated_cpus_lock);
399 num_cpus = acpi_pad_pur(handle);
400 if (num_cpus < 0) {
401 mutex_unlock(&isolated_cpus_lock);
402 return;
403 }
404 acpi_pad_idle_cpus(num_cpus);
405 idle_cpus = acpi_pad_idle_cpus_num();
406 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
407 mutex_unlock(&isolated_cpus_lock);
408}
409
410static void acpi_pad_notify(acpi_handle handle, u32 event,
411 void *data)
412{
413 struct acpi_device *device = data;
414
415 switch (event) {
416 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
417 acpi_pad_handle_notify(handle);
418 acpi_bus_generate_netlink_event(device->pnp.device_class,
419 dev_name(&device->dev), event, 0);
420 break;
421 default:
422 pr_warn("Unsupported event [0x%x]\n", event);
423 break;
424 }
425}
426
427static int acpi_pad_add(struct acpi_device *device)
428{
429 acpi_status status;
430
431 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
432 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
433
434 if (acpi_pad_add_sysfs(device))
435 return -ENODEV;
436
437 status = acpi_install_notify_handler(device->handle,
438 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
439 if (ACPI_FAILURE(status)) {
440 acpi_pad_remove_sysfs(device);
441 return -ENODEV;
442 }
443
444 return 0;
445}
446
447static int acpi_pad_remove(struct acpi_device *device)
448{
449 mutex_lock(&isolated_cpus_lock);
450 acpi_pad_idle_cpus(0);
451 mutex_unlock(&isolated_cpus_lock);
452
453 acpi_remove_notify_handler(device->handle,
454 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
455 acpi_pad_remove_sysfs(device);
456 return 0;
457}
458
459static const struct acpi_device_id pad_device_ids[] = {
460 {"ACPI000C", 0},
461 {"", 0},
462};
463MODULE_DEVICE_TABLE(acpi, pad_device_ids);
464
465static struct acpi_driver acpi_pad_driver = {
466 .name = "processor_aggregator",
467 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
468 .ids = pad_device_ids,
469 .ops = {
470 .add = acpi_pad_add,
471 .remove = acpi_pad_remove,
472 },
473};
474
475static int __init acpi_pad_init(void)
476{
477 /* Xen ACPI PAD is used when running as Xen Dom0. */
478 if (xen_initial_domain())
479 return -ENODEV;
480
481 power_saving_mwait_init();
482 if (power_saving_mwait_eax == 0)
483 return -EINVAL;
484
485 return acpi_bus_register_driver(&acpi_pad_driver);
486}
487
488static void __exit acpi_pad_exit(void)
489{
490 acpi_bus_unregister_driver(&acpi_pad_driver);
491}
492
493module_init(acpi_pad_init);
494module_exit(acpi_pad_exit);
495MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
496MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
497MODULE_LICENSE("GPL");
1/*
2 * acpi_pad.c ACPI Processor Aggregator Driver
3 *
4 * Copyright (c) 2009, Intel Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 */
20
21#include <linux/kernel.h>
22#include <linux/cpumask.h>
23#include <linux/module.h>
24#include <linux/init.h>
25#include <linux/types.h>
26#include <linux/kthread.h>
27#include <linux/freezer.h>
28#include <linux/cpu.h>
29#include <linux/clockchips.h>
30#include <linux/slab.h>
31#include <linux/acpi.h>
32#include <asm/mwait.h>
33
34#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
35#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
36#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
37static DEFINE_MUTEX(isolated_cpus_lock);
38static DEFINE_MUTEX(round_robin_lock);
39
40static unsigned long power_saving_mwait_eax;
41
42static unsigned char tsc_detected_unstable;
43static unsigned char tsc_marked_unstable;
44static unsigned char lapic_detected_unstable;
45static unsigned char lapic_marked_unstable;
46
47static void power_saving_mwait_init(void)
48{
49 unsigned int eax, ebx, ecx, edx;
50 unsigned int highest_cstate = 0;
51 unsigned int highest_subcstate = 0;
52 int i;
53
54 if (!boot_cpu_has(X86_FEATURE_MWAIT))
55 return;
56 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
57 return;
58
59 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
60
61 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
62 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
63 return;
64
65 edx >>= MWAIT_SUBSTATE_SIZE;
66 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
67 if (edx & MWAIT_SUBSTATE_MASK) {
68 highest_cstate = i;
69 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
70 }
71 }
72 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
73 (highest_subcstate - 1);
74
75#if defined(CONFIG_X86)
76 switch (boot_cpu_data.x86_vendor) {
77 case X86_VENDOR_AMD:
78 case X86_VENDOR_INTEL:
79 /*
80 * AMD Fam10h TSC will tick in all
81 * C/P/S0/S1 states when this bit is set.
82 */
83 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
84 tsc_detected_unstable = 1;
85 if (!boot_cpu_has(X86_FEATURE_ARAT))
86 lapic_detected_unstable = 1;
87 break;
88 default:
89 /* TSC & LAPIC could halt in idle */
90 tsc_detected_unstable = 1;
91 lapic_detected_unstable = 1;
92 }
93#endif
94}
95
96static unsigned long cpu_weight[NR_CPUS];
97static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
98static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
99static void round_robin_cpu(unsigned int tsk_index)
100{
101 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
102 cpumask_var_t tmp;
103 int cpu;
104 unsigned long min_weight = -1;
105 unsigned long uninitialized_var(preferred_cpu);
106
107 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
108 return;
109
110 mutex_lock(&round_robin_lock);
111 cpumask_clear(tmp);
112 for_each_cpu(cpu, pad_busy_cpus)
113 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
114 cpumask_andnot(tmp, cpu_online_mask, tmp);
115 /* avoid HT sibilings if possible */
116 if (cpumask_empty(tmp))
117 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
118 if (cpumask_empty(tmp)) {
119 mutex_unlock(&round_robin_lock);
120 return;
121 }
122 for_each_cpu(cpu, tmp) {
123 if (cpu_weight[cpu] < min_weight) {
124 min_weight = cpu_weight[cpu];
125 preferred_cpu = cpu;
126 }
127 }
128
129 if (tsk_in_cpu[tsk_index] != -1)
130 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
131 tsk_in_cpu[tsk_index] = preferred_cpu;
132 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
133 cpu_weight[preferred_cpu]++;
134 mutex_unlock(&round_robin_lock);
135
136 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
137}
138
139static void exit_round_robin(unsigned int tsk_index)
140{
141 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
142 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
143 tsk_in_cpu[tsk_index] = -1;
144}
145
146static unsigned int idle_pct = 5; /* percentage */
147static unsigned int round_robin_time = 1; /* second */
148static int power_saving_thread(void *data)
149{
150 struct sched_param param = {.sched_priority = 1};
151 int do_sleep;
152 unsigned int tsk_index = (unsigned long)data;
153 u64 last_jiffies = 0;
154
155 sched_setscheduler(current, SCHED_RR, ¶m);
156
157 while (!kthread_should_stop()) {
158 int cpu;
159 u64 expire_time;
160
161 try_to_freeze();
162
163 /* round robin to cpus */
164 if (last_jiffies + round_robin_time * HZ < jiffies) {
165 last_jiffies = jiffies;
166 round_robin_cpu(tsk_index);
167 }
168
169 do_sleep = 0;
170
171 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
172
173 while (!need_resched()) {
174 if (tsc_detected_unstable && !tsc_marked_unstable) {
175 /* TSC could halt in idle, so notify users */
176 mark_tsc_unstable("TSC halts in idle");
177 tsc_marked_unstable = 1;
178 }
179 if (lapic_detected_unstable && !lapic_marked_unstable) {
180 int i;
181 /* LAPIC could halt in idle, so notify users */
182 for_each_online_cpu(i)
183 clockevents_notify(
184 CLOCK_EVT_NOTIFY_BROADCAST_ON,
185 &i);
186 lapic_marked_unstable = 1;
187 }
188 local_irq_disable();
189 cpu = smp_processor_id();
190 if (lapic_marked_unstable)
191 clockevents_notify(
192 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
193 stop_critical_timings();
194
195 mwait_idle_with_hints(power_saving_mwait_eax, 1);
196
197 start_critical_timings();
198 if (lapic_marked_unstable)
199 clockevents_notify(
200 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
201 local_irq_enable();
202
203 if (jiffies > expire_time) {
204 do_sleep = 1;
205 break;
206 }
207 }
208
209 /*
210 * current sched_rt has threshold for rt task running time.
211 * When a rt task uses 95% CPU time, the rt thread will be
212 * scheduled out for 5% CPU time to not starve other tasks. But
213 * the mechanism only works when all CPUs have RT task running,
214 * as if one CPU hasn't RT task, RT task from other CPUs will
215 * borrow CPU time from this CPU and cause RT task use > 95%
216 * CPU time. To make 'avoid starvation' work, takes a nap here.
217 */
218 if (do_sleep)
219 schedule_timeout_killable(HZ * idle_pct / 100);
220 }
221
222 exit_round_robin(tsk_index);
223 return 0;
224}
225
226static struct task_struct *ps_tsks[NR_CPUS];
227static unsigned int ps_tsk_num;
228static int create_power_saving_task(void)
229{
230 int rc;
231
232 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
233 (void *)(unsigned long)ps_tsk_num,
234 "acpi_pad/%d", ps_tsk_num);
235
236 if (IS_ERR(ps_tsks[ps_tsk_num])) {
237 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
238 ps_tsks[ps_tsk_num] = NULL;
239 } else {
240 rc = 0;
241 ps_tsk_num++;
242 }
243
244 return rc;
245}
246
247static void destroy_power_saving_task(void)
248{
249 if (ps_tsk_num > 0) {
250 ps_tsk_num--;
251 kthread_stop(ps_tsks[ps_tsk_num]);
252 ps_tsks[ps_tsk_num] = NULL;
253 }
254}
255
256static void set_power_saving_task_num(unsigned int num)
257{
258 if (num > ps_tsk_num) {
259 while (ps_tsk_num < num) {
260 if (create_power_saving_task())
261 return;
262 }
263 } else if (num < ps_tsk_num) {
264 while (ps_tsk_num > num)
265 destroy_power_saving_task();
266 }
267}
268
269static void acpi_pad_idle_cpus(unsigned int num_cpus)
270{
271 get_online_cpus();
272
273 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
274 set_power_saving_task_num(num_cpus);
275
276 put_online_cpus();
277}
278
279static uint32_t acpi_pad_idle_cpus_num(void)
280{
281 return ps_tsk_num;
282}
283
284static ssize_t acpi_pad_rrtime_store(struct device *dev,
285 struct device_attribute *attr, const char *buf, size_t count)
286{
287 unsigned long num;
288 if (kstrtoul(buf, 0, &num))
289 return -EINVAL;
290 if (num < 1 || num >= 100)
291 return -EINVAL;
292 mutex_lock(&isolated_cpus_lock);
293 round_robin_time = num;
294 mutex_unlock(&isolated_cpus_lock);
295 return count;
296}
297
298static ssize_t acpi_pad_rrtime_show(struct device *dev,
299 struct device_attribute *attr, char *buf)
300{
301 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
302}
303static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
304 acpi_pad_rrtime_show,
305 acpi_pad_rrtime_store);
306
307static ssize_t acpi_pad_idlepct_store(struct device *dev,
308 struct device_attribute *attr, const char *buf, size_t count)
309{
310 unsigned long num;
311 if (kstrtoul(buf, 0, &num))
312 return -EINVAL;
313 if (num < 1 || num >= 100)
314 return -EINVAL;
315 mutex_lock(&isolated_cpus_lock);
316 idle_pct = num;
317 mutex_unlock(&isolated_cpus_lock);
318 return count;
319}
320
321static ssize_t acpi_pad_idlepct_show(struct device *dev,
322 struct device_attribute *attr, char *buf)
323{
324 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
325}
326static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
327 acpi_pad_idlepct_show,
328 acpi_pad_idlepct_store);
329
330static ssize_t acpi_pad_idlecpus_store(struct device *dev,
331 struct device_attribute *attr, const char *buf, size_t count)
332{
333 unsigned long num;
334 if (kstrtoul(buf, 0, &num))
335 return -EINVAL;
336 mutex_lock(&isolated_cpus_lock);
337 acpi_pad_idle_cpus(num);
338 mutex_unlock(&isolated_cpus_lock);
339 return count;
340}
341
342static ssize_t acpi_pad_idlecpus_show(struct device *dev,
343 struct device_attribute *attr, char *buf)
344{
345 int n = 0;
346 n = cpumask_scnprintf(buf, PAGE_SIZE-2, to_cpumask(pad_busy_cpus_bits));
347 buf[n++] = '\n';
348 buf[n] = '\0';
349 return n;
350}
351static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
352 acpi_pad_idlecpus_show,
353 acpi_pad_idlecpus_store);
354
355static int acpi_pad_add_sysfs(struct acpi_device *device)
356{
357 int result;
358
359 result = device_create_file(&device->dev, &dev_attr_idlecpus);
360 if (result)
361 return -ENODEV;
362 result = device_create_file(&device->dev, &dev_attr_idlepct);
363 if (result) {
364 device_remove_file(&device->dev, &dev_attr_idlecpus);
365 return -ENODEV;
366 }
367 result = device_create_file(&device->dev, &dev_attr_rrtime);
368 if (result) {
369 device_remove_file(&device->dev, &dev_attr_idlecpus);
370 device_remove_file(&device->dev, &dev_attr_idlepct);
371 return -ENODEV;
372 }
373 return 0;
374}
375
376static void acpi_pad_remove_sysfs(struct acpi_device *device)
377{
378 device_remove_file(&device->dev, &dev_attr_idlecpus);
379 device_remove_file(&device->dev, &dev_attr_idlepct);
380 device_remove_file(&device->dev, &dev_attr_rrtime);
381}
382
383/*
384 * Query firmware how many CPUs should be idle
385 * return -1 on failure
386 */
387static int acpi_pad_pur(acpi_handle handle)
388{
389 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
390 union acpi_object *package;
391 int num = -1;
392
393 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
394 return num;
395
396 if (!buffer.length || !buffer.pointer)
397 return num;
398
399 package = buffer.pointer;
400
401 if (package->type == ACPI_TYPE_PACKAGE &&
402 package->package.count == 2 &&
403 package->package.elements[0].integer.value == 1) /* rev 1 */
404
405 num = package->package.elements[1].integer.value;
406
407 kfree(buffer.pointer);
408 return num;
409}
410
411static void acpi_pad_handle_notify(acpi_handle handle)
412{
413 int num_cpus;
414 uint32_t idle_cpus;
415 struct acpi_buffer param = {
416 .length = 4,
417 .pointer = (void *)&idle_cpus,
418 };
419
420 mutex_lock(&isolated_cpus_lock);
421 num_cpus = acpi_pad_pur(handle);
422 if (num_cpus < 0) {
423 mutex_unlock(&isolated_cpus_lock);
424 return;
425 }
426 acpi_pad_idle_cpus(num_cpus);
427 idle_cpus = acpi_pad_idle_cpus_num();
428 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
429 mutex_unlock(&isolated_cpus_lock);
430}
431
432static void acpi_pad_notify(acpi_handle handle, u32 event,
433 void *data)
434{
435 struct acpi_device *device = data;
436
437 switch (event) {
438 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
439 acpi_pad_handle_notify(handle);
440 acpi_bus_generate_netlink_event(device->pnp.device_class,
441 dev_name(&device->dev), event, 0);
442 break;
443 default:
444 pr_warn("Unsupported event [0x%x]\n", event);
445 break;
446 }
447}
448
449static int acpi_pad_add(struct acpi_device *device)
450{
451 acpi_status status;
452
453 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
454 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
455
456 if (acpi_pad_add_sysfs(device))
457 return -ENODEV;
458
459 status = acpi_install_notify_handler(device->handle,
460 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
461 if (ACPI_FAILURE(status)) {
462 acpi_pad_remove_sysfs(device);
463 return -ENODEV;
464 }
465
466 return 0;
467}
468
469static int acpi_pad_remove(struct acpi_device *device)
470{
471 mutex_lock(&isolated_cpus_lock);
472 acpi_pad_idle_cpus(0);
473 mutex_unlock(&isolated_cpus_lock);
474
475 acpi_remove_notify_handler(device->handle,
476 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
477 acpi_pad_remove_sysfs(device);
478 return 0;
479}
480
481static const struct acpi_device_id pad_device_ids[] = {
482 {"ACPI000C", 0},
483 {"", 0},
484};
485MODULE_DEVICE_TABLE(acpi, pad_device_ids);
486
487static struct acpi_driver acpi_pad_driver = {
488 .name = "processor_aggregator",
489 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
490 .ids = pad_device_ids,
491 .ops = {
492 .add = acpi_pad_add,
493 .remove = acpi_pad_remove,
494 },
495};
496
497static int __init acpi_pad_init(void)
498{
499 power_saving_mwait_init();
500 if (power_saving_mwait_eax == 0)
501 return -EINVAL;
502
503 return acpi_bus_register_driver(&acpi_pad_driver);
504}
505
506static void __exit acpi_pad_exit(void)
507{
508 acpi_bus_unregister_driver(&acpi_pad_driver);
509}
510
511module_init(acpi_pad_init);
512module_exit(acpi_pad_exit);
513MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
514MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
515MODULE_LICENSE("GPL");