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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 <acpi/acpi_bus.h>
32#include <acpi/acpi_drivers.h>
33#include <asm/mwait.h>
34
35#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
36#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
37#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
38static DEFINE_MUTEX(isolated_cpus_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(&isolated_cpus_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(&isolated_cpus_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(&isolated_cpus_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 = 10; /* 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 __monitor((void *)¤t_thread_info()->flags, 0, 0);
196 smp_mb();
197 if (!need_resched())
198 __mwait(power_saving_mwait_eax, 1);
199
200 start_critical_timings();
201 if (lapic_marked_unstable)
202 clockevents_notify(
203 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
204 local_irq_enable();
205
206 if (jiffies > expire_time) {
207 do_sleep = 1;
208 break;
209 }
210 }
211
212 /*
213 * current sched_rt has threshold for rt task running time.
214 * When a rt task uses 95% CPU time, the rt thread will be
215 * scheduled out for 5% CPU time to not starve other tasks. But
216 * the mechanism only works when all CPUs have RT task running,
217 * as if one CPU hasn't RT task, RT task from other CPUs will
218 * borrow CPU time from this CPU and cause RT task use > 95%
219 * CPU time. To make 'avoid starvation' work, takes a nap here.
220 */
221 if (do_sleep)
222 schedule_timeout_killable(HZ * idle_pct / 100);
223 }
224
225 exit_round_robin(tsk_index);
226 return 0;
227}
228
229static struct task_struct *ps_tsks[NR_CPUS];
230static unsigned int ps_tsk_num;
231static int create_power_saving_task(void)
232{
233 int rc = -ENOMEM;
234
235 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
236 (void *)(unsigned long)ps_tsk_num,
237 "power_saving/%d", ps_tsk_num);
238 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
239 if (!rc)
240 ps_tsk_num++;
241 else
242 ps_tsks[ps_tsk_num] = NULL;
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 (strict_strtoul(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 (strict_strtoul(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 (strict_strtoul(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
411/* Notify firmware how many CPUs are idle */
412static void acpi_pad_ost(acpi_handle handle, int stat,
413 uint32_t idle_cpus)
414{
415 union acpi_object params[3] = {
416 {.type = ACPI_TYPE_INTEGER,},
417 {.type = ACPI_TYPE_INTEGER,},
418 {.type = ACPI_TYPE_BUFFER,},
419 };
420 struct acpi_object_list arg_list = {3, params};
421
422 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
423 params[1].integer.value = stat;
424 params[2].buffer.length = 4;
425 params[2].buffer.pointer = (void *)&idle_cpus;
426 acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
427}
428
429static void acpi_pad_handle_notify(acpi_handle handle)
430{
431 int num_cpus;
432 uint32_t idle_cpus;
433
434 mutex_lock(&isolated_cpus_lock);
435 num_cpus = acpi_pad_pur(handle);
436 if (num_cpus < 0) {
437 mutex_unlock(&isolated_cpus_lock);
438 return;
439 }
440 acpi_pad_idle_cpus(num_cpus);
441 idle_cpus = acpi_pad_idle_cpus_num();
442 acpi_pad_ost(handle, 0, idle_cpus);
443 mutex_unlock(&isolated_cpus_lock);
444}
445
446static void acpi_pad_notify(acpi_handle handle, u32 event,
447 void *data)
448{
449 struct acpi_device *device = data;
450
451 switch (event) {
452 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
453 acpi_pad_handle_notify(handle);
454 acpi_bus_generate_proc_event(device, event, 0);
455 acpi_bus_generate_netlink_event(device->pnp.device_class,
456 dev_name(&device->dev), event, 0);
457 break;
458 default:
459 printk(KERN_WARNING "Unsupported event [0x%x]\n", event);
460 break;
461 }
462}
463
464static int acpi_pad_add(struct acpi_device *device)
465{
466 acpi_status status;
467
468 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
469 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
470
471 if (acpi_pad_add_sysfs(device))
472 return -ENODEV;
473
474 status = acpi_install_notify_handler(device->handle,
475 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
476 if (ACPI_FAILURE(status)) {
477 acpi_pad_remove_sysfs(device);
478 return -ENODEV;
479 }
480
481 return 0;
482}
483
484static int acpi_pad_remove(struct acpi_device *device,
485 int type)
486{
487 mutex_lock(&isolated_cpus_lock);
488 acpi_pad_idle_cpus(0);
489 mutex_unlock(&isolated_cpus_lock);
490
491 acpi_remove_notify_handler(device->handle,
492 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
493 acpi_pad_remove_sysfs(device);
494 return 0;
495}
496
497static const struct acpi_device_id pad_device_ids[] = {
498 {"ACPI000C", 0},
499 {"", 0},
500};
501MODULE_DEVICE_TABLE(acpi, pad_device_ids);
502
503static struct acpi_driver acpi_pad_driver = {
504 .name = "processor_aggregator",
505 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
506 .ids = pad_device_ids,
507 .ops = {
508 .add = acpi_pad_add,
509 .remove = acpi_pad_remove,
510 },
511};
512
513static int __init acpi_pad_init(void)
514{
515 power_saving_mwait_init();
516 if (power_saving_mwait_eax == 0)
517 return -EINVAL;
518
519 return acpi_bus_register_driver(&acpi_pad_driver);
520}
521
522static void __exit acpi_pad_exit(void)
523{
524 acpi_bus_unregister_driver(&acpi_pad_driver);
525}
526
527module_init(acpi_pad_init);
528module_exit(acpi_pad_exit);
529MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
530MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
531MODULE_LICENSE("GPL");
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 <linux/perf_event.h>
21#include <asm/mwait.h>
22#include <xen/xen.h>
23
24#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
25#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
26#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
27static DEFINE_MUTEX(isolated_cpus_lock);
28static DEFINE_MUTEX(round_robin_lock);
29
30static unsigned long power_saving_mwait_eax;
31
32static unsigned char tsc_detected_unstable;
33static unsigned char tsc_marked_unstable;
34
35static void power_saving_mwait_init(void)
36{
37 unsigned int eax, ebx, ecx, edx;
38 unsigned int highest_cstate = 0;
39 unsigned int highest_subcstate = 0;
40 int i;
41
42 if (!boot_cpu_has(X86_FEATURE_MWAIT))
43 return;
44 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
45 return;
46
47 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
48
49 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
50 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
51 return;
52
53 edx >>= MWAIT_SUBSTATE_SIZE;
54 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
55 if (edx & MWAIT_SUBSTATE_MASK) {
56 highest_cstate = i;
57 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
58 }
59 }
60 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
61 (highest_subcstate - 1);
62
63#if defined(CONFIG_X86)
64 switch (boot_cpu_data.x86_vendor) {
65 case X86_VENDOR_HYGON:
66 case X86_VENDOR_AMD:
67 case X86_VENDOR_INTEL:
68 case X86_VENDOR_ZHAOXIN:
69 /*
70 * AMD Fam10h TSC will tick in all
71 * C/P/S0/S1 states when this bit is set.
72 */
73 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
74 tsc_detected_unstable = 1;
75 break;
76 default:
77 /* TSC could halt in idle */
78 tsc_detected_unstable = 1;
79 }
80#endif
81}
82
83static unsigned long cpu_weight[NR_CPUS];
84static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
85static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
86static void round_robin_cpu(unsigned int tsk_index)
87{
88 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
89 cpumask_var_t tmp;
90 int cpu;
91 unsigned long min_weight = -1;
92 unsigned long preferred_cpu;
93
94 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
95 return;
96
97 mutex_lock(&round_robin_lock);
98 cpumask_clear(tmp);
99 for_each_cpu(cpu, pad_busy_cpus)
100 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
101 cpumask_andnot(tmp, cpu_online_mask, tmp);
102 /* avoid HT sibilings if possible */
103 if (cpumask_empty(tmp))
104 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
105 if (cpumask_empty(tmp)) {
106 mutex_unlock(&round_robin_lock);
107 free_cpumask_var(tmp);
108 return;
109 }
110 for_each_cpu(cpu, tmp) {
111 if (cpu_weight[cpu] < min_weight) {
112 min_weight = cpu_weight[cpu];
113 preferred_cpu = cpu;
114 }
115 }
116
117 if (tsk_in_cpu[tsk_index] != -1)
118 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
119 tsk_in_cpu[tsk_index] = preferred_cpu;
120 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
121 cpu_weight[preferred_cpu]++;
122 mutex_unlock(&round_robin_lock);
123
124 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
125
126 free_cpumask_var(tmp);
127}
128
129static void exit_round_robin(unsigned int tsk_index)
130{
131 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
132
133 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
134 tsk_in_cpu[tsk_index] = -1;
135}
136
137static unsigned int idle_pct = 5; /* percentage */
138static unsigned int round_robin_time = 1; /* second */
139static int power_saving_thread(void *data)
140{
141 int do_sleep;
142 unsigned int tsk_index = (unsigned long)data;
143 u64 last_jiffies = 0;
144
145 sched_set_fifo_low(current);
146
147 while (!kthread_should_stop()) {
148 unsigned long expire_time;
149
150 /* round robin to cpus */
151 expire_time = last_jiffies + round_robin_time * HZ;
152 if (time_before(expire_time, jiffies)) {
153 last_jiffies = jiffies;
154 round_robin_cpu(tsk_index);
155 }
156
157 do_sleep = 0;
158
159 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
160
161 while (!need_resched()) {
162 if (tsc_detected_unstable && !tsc_marked_unstable) {
163 /* TSC could halt in idle, so notify users */
164 mark_tsc_unstable("TSC halts in idle");
165 tsc_marked_unstable = 1;
166 }
167 local_irq_disable();
168
169 perf_lopwr_cb(true);
170
171 tick_broadcast_enable();
172 tick_broadcast_enter();
173 stop_critical_timings();
174
175 mwait_idle_with_hints(power_saving_mwait_eax, 1);
176
177 start_critical_timings();
178 tick_broadcast_exit();
179
180 perf_lopwr_cb(false);
181
182 local_irq_enable();
183
184 if (time_before(expire_time, jiffies)) {
185 do_sleep = 1;
186 break;
187 }
188 }
189
190 /*
191 * current sched_rt has threshold for rt task running time.
192 * When a rt task uses 95% CPU time, the rt thread will be
193 * scheduled out for 5% CPU time to not starve other tasks. But
194 * the mechanism only works when all CPUs have RT task running,
195 * as if one CPU hasn't RT task, RT task from other CPUs will
196 * borrow CPU time from this CPU and cause RT task use > 95%
197 * CPU time. To make 'avoid starvation' work, takes a nap here.
198 */
199 if (unlikely(do_sleep))
200 schedule_timeout_killable(HZ * idle_pct / 100);
201
202 /* If an external event has set the need_resched flag, then
203 * we need to deal with it, or this loop will continue to
204 * spin without calling __mwait().
205 */
206 if (unlikely(need_resched()))
207 schedule();
208 }
209
210 exit_round_robin(tsk_index);
211 return 0;
212}
213
214static struct task_struct *ps_tsks[NR_CPUS];
215static unsigned int ps_tsk_num;
216static int create_power_saving_task(void)
217{
218 int rc;
219
220 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
221 (void *)(unsigned long)ps_tsk_num,
222 "acpi_pad/%d", ps_tsk_num);
223
224 if (IS_ERR(ps_tsks[ps_tsk_num])) {
225 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
226 ps_tsks[ps_tsk_num] = NULL;
227 } else {
228 rc = 0;
229 ps_tsk_num++;
230 }
231
232 return rc;
233}
234
235static void destroy_power_saving_task(void)
236{
237 if (ps_tsk_num > 0) {
238 ps_tsk_num--;
239 kthread_stop(ps_tsks[ps_tsk_num]);
240 ps_tsks[ps_tsk_num] = NULL;
241 }
242}
243
244static void set_power_saving_task_num(unsigned int num)
245{
246 if (num > ps_tsk_num) {
247 while (ps_tsk_num < num) {
248 if (create_power_saving_task())
249 return;
250 }
251 } else if (num < ps_tsk_num) {
252 while (ps_tsk_num > num)
253 destroy_power_saving_task();
254 }
255}
256
257static void acpi_pad_idle_cpus(unsigned int num_cpus)
258{
259 cpus_read_lock();
260
261 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
262 set_power_saving_task_num(num_cpus);
263
264 cpus_read_unlock();
265}
266
267static uint32_t acpi_pad_idle_cpus_num(void)
268{
269 return ps_tsk_num;
270}
271
272static ssize_t rrtime_store(struct device *dev,
273 struct device_attribute *attr, const char *buf, size_t count)
274{
275 unsigned long num;
276
277 if (kstrtoul(buf, 0, &num))
278 return -EINVAL;
279 if (num < 1 || num >= 100)
280 return -EINVAL;
281 mutex_lock(&isolated_cpus_lock);
282 round_robin_time = num;
283 mutex_unlock(&isolated_cpus_lock);
284 return count;
285}
286
287static ssize_t rrtime_show(struct device *dev,
288 struct device_attribute *attr, char *buf)
289{
290 return sysfs_emit(buf, "%d\n", round_robin_time);
291}
292static DEVICE_ATTR_RW(rrtime);
293
294static ssize_t idlepct_store(struct device *dev,
295 struct device_attribute *attr, const char *buf, size_t count)
296{
297 unsigned long num;
298
299 if (kstrtoul(buf, 0, &num))
300 return -EINVAL;
301 if (num < 1 || num >= 100)
302 return -EINVAL;
303 mutex_lock(&isolated_cpus_lock);
304 idle_pct = num;
305 mutex_unlock(&isolated_cpus_lock);
306 return count;
307}
308
309static ssize_t idlepct_show(struct device *dev,
310 struct device_attribute *attr, char *buf)
311{
312 return sysfs_emit(buf, "%d\n", idle_pct);
313}
314static DEVICE_ATTR_RW(idlepct);
315
316static ssize_t idlecpus_store(struct device *dev,
317 struct device_attribute *attr, const char *buf, size_t count)
318{
319 unsigned long num;
320
321 if (kstrtoul(buf, 0, &num))
322 return -EINVAL;
323 mutex_lock(&isolated_cpus_lock);
324 acpi_pad_idle_cpus(num);
325 mutex_unlock(&isolated_cpus_lock);
326 return count;
327}
328
329static ssize_t idlecpus_show(struct device *dev,
330 struct device_attribute *attr, char *buf)
331{
332 return cpumap_print_to_pagebuf(false, buf,
333 to_cpumask(pad_busy_cpus_bits));
334}
335
336static DEVICE_ATTR_RW(idlecpus);
337
338static int acpi_pad_add_sysfs(struct acpi_device *device)
339{
340 int result;
341
342 result = device_create_file(&device->dev, &dev_attr_idlecpus);
343 if (result)
344 return -ENODEV;
345 result = device_create_file(&device->dev, &dev_attr_idlepct);
346 if (result) {
347 device_remove_file(&device->dev, &dev_attr_idlecpus);
348 return -ENODEV;
349 }
350 result = device_create_file(&device->dev, &dev_attr_rrtime);
351 if (result) {
352 device_remove_file(&device->dev, &dev_attr_idlecpus);
353 device_remove_file(&device->dev, &dev_attr_idlepct);
354 return -ENODEV;
355 }
356 return 0;
357}
358
359static void acpi_pad_remove_sysfs(struct acpi_device *device)
360{
361 device_remove_file(&device->dev, &dev_attr_idlecpus);
362 device_remove_file(&device->dev, &dev_attr_idlepct);
363 device_remove_file(&device->dev, &dev_attr_rrtime);
364}
365
366/*
367 * Query firmware how many CPUs should be idle
368 * return -1 on failure
369 */
370static int acpi_pad_pur(acpi_handle handle)
371{
372 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
373 union acpi_object *package;
374 int num = -1;
375
376 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
377 return num;
378
379 if (!buffer.length || !buffer.pointer)
380 return num;
381
382 package = buffer.pointer;
383
384 if (package->type == ACPI_TYPE_PACKAGE &&
385 package->package.count == 2 &&
386 package->package.elements[0].integer.value == 1) /* rev 1 */
387
388 num = package->package.elements[1].integer.value;
389
390 kfree(buffer.pointer);
391 return num;
392}
393
394static void acpi_pad_handle_notify(acpi_handle handle)
395{
396 int num_cpus;
397 uint32_t idle_cpus;
398 struct acpi_buffer param = {
399 .length = 4,
400 .pointer = (void *)&idle_cpus,
401 };
402
403 mutex_lock(&isolated_cpus_lock);
404 num_cpus = acpi_pad_pur(handle);
405 if (num_cpus < 0) {
406 mutex_unlock(&isolated_cpus_lock);
407 return;
408 }
409 acpi_pad_idle_cpus(num_cpus);
410 idle_cpus = acpi_pad_idle_cpus_num();
411 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
412 mutex_unlock(&isolated_cpus_lock);
413}
414
415static void acpi_pad_notify(acpi_handle handle, u32 event,
416 void *data)
417{
418 struct acpi_device *device = data;
419
420 switch (event) {
421 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
422 acpi_pad_handle_notify(handle);
423 acpi_bus_generate_netlink_event(device->pnp.device_class,
424 dev_name(&device->dev), event, 0);
425 break;
426 default:
427 pr_warn("Unsupported event [0x%x]\n", event);
428 break;
429 }
430}
431
432static int acpi_pad_add(struct acpi_device *device)
433{
434 acpi_status status;
435
436 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
437 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
438
439 if (acpi_pad_add_sysfs(device))
440 return -ENODEV;
441
442 status = acpi_install_notify_handler(device->handle,
443 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
444 if (ACPI_FAILURE(status)) {
445 acpi_pad_remove_sysfs(device);
446 return -ENODEV;
447 }
448
449 return 0;
450}
451
452static void acpi_pad_remove(struct acpi_device *device)
453{
454 mutex_lock(&isolated_cpus_lock);
455 acpi_pad_idle_cpus(0);
456 mutex_unlock(&isolated_cpus_lock);
457
458 acpi_remove_notify_handler(device->handle,
459 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
460 acpi_pad_remove_sysfs(device);
461}
462
463static const struct acpi_device_id pad_device_ids[] = {
464 {"ACPI000C", 0},
465 {"", 0},
466};
467MODULE_DEVICE_TABLE(acpi, pad_device_ids);
468
469static struct acpi_driver acpi_pad_driver = {
470 .name = "processor_aggregator",
471 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
472 .ids = pad_device_ids,
473 .ops = {
474 .add = acpi_pad_add,
475 .remove = acpi_pad_remove,
476 },
477};
478
479static int __init acpi_pad_init(void)
480{
481 /* Xen ACPI PAD is used when running as Xen Dom0. */
482 if (xen_initial_domain())
483 return -ENODEV;
484
485 power_saving_mwait_init();
486 if (power_saving_mwait_eax == 0)
487 return -EINVAL;
488
489 return acpi_bus_register_driver(&acpi_pad_driver);
490}
491
492static void __exit acpi_pad_exit(void)
493{
494 acpi_bus_unregister_driver(&acpi_pad_driver);
495}
496
497module_init(acpi_pad_init);
498module_exit(acpi_pad_exit);
499MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
500MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
501MODULE_LICENSE("GPL");