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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 */
16
17#include <linux/kernel.h>
18#include <linux/cpumask.h>
19#include <linux/module.h>
20#include <linux/init.h>
21#include <linux/types.h>
22#include <linux/kthread.h>
23#include <linux/freezer.h>
24#include <linux/cpu.h>
25#include <linux/tick.h>
26#include <linux/slab.h>
27#include <linux/acpi.h>
28#include <asm/mwait.h>
29
30#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
31#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
32#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
33static DEFINE_MUTEX(isolated_cpus_lock);
34static DEFINE_MUTEX(round_robin_lock);
35
36static unsigned long power_saving_mwait_eax;
37
38static unsigned char tsc_detected_unstable;
39static unsigned char tsc_marked_unstable;
40
41static void power_saving_mwait_init(void)
42{
43 unsigned int eax, ebx, ecx, edx;
44 unsigned int highest_cstate = 0;
45 unsigned int highest_subcstate = 0;
46 int i;
47
48 if (!boot_cpu_has(X86_FEATURE_MWAIT))
49 return;
50 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
51 return;
52
53 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
54
55 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
56 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
57 return;
58
59 edx >>= MWAIT_SUBSTATE_SIZE;
60 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
61 if (edx & MWAIT_SUBSTATE_MASK) {
62 highest_cstate = i;
63 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
64 }
65 }
66 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
67 (highest_subcstate - 1);
68
69#if defined(CONFIG_X86)
70 switch (boot_cpu_data.x86_vendor) {
71 case X86_VENDOR_AMD:
72 case X86_VENDOR_INTEL:
73 /*
74 * AMD Fam10h TSC will tick in all
75 * C/P/S0/S1 states when this bit is set.
76 */
77 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
78 tsc_detected_unstable = 1;
79 break;
80 default:
81 /* TSC could halt in idle */
82 tsc_detected_unstable = 1;
83 }
84#endif
85}
86
87static unsigned long cpu_weight[NR_CPUS];
88static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
89static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
90static void round_robin_cpu(unsigned int tsk_index)
91{
92 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
93 cpumask_var_t tmp;
94 int cpu;
95 unsigned long min_weight = -1;
96 unsigned long uninitialized_var(preferred_cpu);
97
98 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
99 return;
100
101 mutex_lock(&round_robin_lock);
102 cpumask_clear(tmp);
103 for_each_cpu(cpu, pad_busy_cpus)
104 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
105 cpumask_andnot(tmp, cpu_online_mask, tmp);
106 /* avoid HT sibilings if possible */
107 if (cpumask_empty(tmp))
108 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
109 if (cpumask_empty(tmp)) {
110 mutex_unlock(&round_robin_lock);
111 return;
112 }
113 for_each_cpu(cpu, tmp) {
114 if (cpu_weight[cpu] < min_weight) {
115 min_weight = cpu_weight[cpu];
116 preferred_cpu = cpu;
117 }
118 }
119
120 if (tsk_in_cpu[tsk_index] != -1)
121 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
122 tsk_in_cpu[tsk_index] = preferred_cpu;
123 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
124 cpu_weight[preferred_cpu]++;
125 mutex_unlock(&round_robin_lock);
126
127 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
128}
129
130static void exit_round_robin(unsigned int tsk_index)
131{
132 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
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 struct sched_param param = {.sched_priority = 1};
142 int do_sleep;
143 unsigned int tsk_index = (unsigned long)data;
144 u64 last_jiffies = 0;
145
146 sched_setscheduler(current, SCHED_RR, ¶m);
147
148 while (!kthread_should_stop()) {
149 unsigned long expire_time;
150
151 /* round robin to cpus */
152 expire_time = last_jiffies + round_robin_time * HZ;
153 if (time_before(expire_time, jiffies)) {
154 last_jiffies = jiffies;
155 round_robin_cpu(tsk_index);
156 }
157
158 do_sleep = 0;
159
160 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
161
162 while (!need_resched()) {
163 if (tsc_detected_unstable && !tsc_marked_unstable) {
164 /* TSC could halt in idle, so notify users */
165 mark_tsc_unstable("TSC halts in idle");
166 tsc_marked_unstable = 1;
167 }
168 local_irq_disable();
169 tick_broadcast_enable();
170 tick_broadcast_enter();
171 stop_critical_timings();
172
173 mwait_idle_with_hints(power_saving_mwait_eax, 1);
174
175 start_critical_timings();
176 tick_broadcast_exit();
177 local_irq_enable();
178
179 if (time_before(expire_time, jiffies)) {
180 do_sleep = 1;
181 break;
182 }
183 }
184
185 /*
186 * current sched_rt has threshold for rt task running time.
187 * When a rt task uses 95% CPU time, the rt thread will be
188 * scheduled out for 5% CPU time to not starve other tasks. But
189 * the mechanism only works when all CPUs have RT task running,
190 * as if one CPU hasn't RT task, RT task from other CPUs will
191 * borrow CPU time from this CPU and cause RT task use > 95%
192 * CPU time. To make 'avoid starvation' work, takes a nap here.
193 */
194 if (unlikely(do_sleep))
195 schedule_timeout_killable(HZ * idle_pct / 100);
196
197 /* If an external event has set the need_resched flag, then
198 * we need to deal with it, or this loop will continue to
199 * spin without calling __mwait().
200 */
201 if (unlikely(need_resched()))
202 schedule();
203 }
204
205 exit_round_robin(tsk_index);
206 return 0;
207}
208
209static struct task_struct *ps_tsks[NR_CPUS];
210static unsigned int ps_tsk_num;
211static int create_power_saving_task(void)
212{
213 int rc;
214
215 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
216 (void *)(unsigned long)ps_tsk_num,
217 "acpi_pad/%d", ps_tsk_num);
218
219 if (IS_ERR(ps_tsks[ps_tsk_num])) {
220 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
221 ps_tsks[ps_tsk_num] = NULL;
222 } else {
223 rc = 0;
224 ps_tsk_num++;
225 }
226
227 return rc;
228}
229
230static void destroy_power_saving_task(void)
231{
232 if (ps_tsk_num > 0) {
233 ps_tsk_num--;
234 kthread_stop(ps_tsks[ps_tsk_num]);
235 ps_tsks[ps_tsk_num] = NULL;
236 }
237}
238
239static void set_power_saving_task_num(unsigned int num)
240{
241 if (num > ps_tsk_num) {
242 while (ps_tsk_num < num) {
243 if (create_power_saving_task())
244 return;
245 }
246 } else if (num < ps_tsk_num) {
247 while (ps_tsk_num > num)
248 destroy_power_saving_task();
249 }
250}
251
252static void acpi_pad_idle_cpus(unsigned int num_cpus)
253{
254 get_online_cpus();
255
256 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
257 set_power_saving_task_num(num_cpus);
258
259 put_online_cpus();
260}
261
262static uint32_t acpi_pad_idle_cpus_num(void)
263{
264 return ps_tsk_num;
265}
266
267static ssize_t acpi_pad_rrtime_store(struct device *dev,
268 struct device_attribute *attr, const char *buf, size_t count)
269{
270 unsigned long num;
271 if (kstrtoul(buf, 0, &num))
272 return -EINVAL;
273 if (num < 1 || num >= 100)
274 return -EINVAL;
275 mutex_lock(&isolated_cpus_lock);
276 round_robin_time = num;
277 mutex_unlock(&isolated_cpus_lock);
278 return count;
279}
280
281static ssize_t acpi_pad_rrtime_show(struct device *dev,
282 struct device_attribute *attr, char *buf)
283{
284 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
285}
286static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
287 acpi_pad_rrtime_show,
288 acpi_pad_rrtime_store);
289
290static ssize_t acpi_pad_idlepct_store(struct device *dev,
291 struct device_attribute *attr, const char *buf, size_t count)
292{
293 unsigned long num;
294 if (kstrtoul(buf, 0, &num))
295 return -EINVAL;
296 if (num < 1 || num >= 100)
297 return -EINVAL;
298 mutex_lock(&isolated_cpus_lock);
299 idle_pct = num;
300 mutex_unlock(&isolated_cpus_lock);
301 return count;
302}
303
304static ssize_t acpi_pad_idlepct_show(struct device *dev,
305 struct device_attribute *attr, char *buf)
306{
307 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
308}
309static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
310 acpi_pad_idlepct_show,
311 acpi_pad_idlepct_store);
312
313static ssize_t acpi_pad_idlecpus_store(struct device *dev,
314 struct device_attribute *attr, const char *buf, size_t count)
315{
316 unsigned long num;
317 if (kstrtoul(buf, 0, &num))
318 return -EINVAL;
319 mutex_lock(&isolated_cpus_lock);
320 acpi_pad_idle_cpus(num);
321 mutex_unlock(&isolated_cpus_lock);
322 return count;
323}
324
325static ssize_t acpi_pad_idlecpus_show(struct device *dev,
326 struct device_attribute *attr, char *buf)
327{
328 return cpumap_print_to_pagebuf(false, buf,
329 to_cpumask(pad_busy_cpus_bits));
330}
331
332static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
333 acpi_pad_idlecpus_show,
334 acpi_pad_idlecpus_store);
335
336static int acpi_pad_add_sysfs(struct acpi_device *device)
337{
338 int result;
339
340 result = device_create_file(&device->dev, &dev_attr_idlecpus);
341 if (result)
342 return -ENODEV;
343 result = device_create_file(&device->dev, &dev_attr_idlepct);
344 if (result) {
345 device_remove_file(&device->dev, &dev_attr_idlecpus);
346 return -ENODEV;
347 }
348 result = device_create_file(&device->dev, &dev_attr_rrtime);
349 if (result) {
350 device_remove_file(&device->dev, &dev_attr_idlecpus);
351 device_remove_file(&device->dev, &dev_attr_idlepct);
352 return -ENODEV;
353 }
354 return 0;
355}
356
357static void acpi_pad_remove_sysfs(struct acpi_device *device)
358{
359 device_remove_file(&device->dev, &dev_attr_idlecpus);
360 device_remove_file(&device->dev, &dev_attr_idlepct);
361 device_remove_file(&device->dev, &dev_attr_rrtime);
362}
363
364/*
365 * Query firmware how many CPUs should be idle
366 * return -1 on failure
367 */
368static int acpi_pad_pur(acpi_handle handle)
369{
370 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
371 union acpi_object *package;
372 int num = -1;
373
374 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
375 return num;
376
377 if (!buffer.length || !buffer.pointer)
378 return num;
379
380 package = buffer.pointer;
381
382 if (package->type == ACPI_TYPE_PACKAGE &&
383 package->package.count == 2 &&
384 package->package.elements[0].integer.value == 1) /* rev 1 */
385
386 num = package->package.elements[1].integer.value;
387
388 kfree(buffer.pointer);
389 return num;
390}
391
392static void acpi_pad_handle_notify(acpi_handle handle)
393{
394 int num_cpus;
395 uint32_t idle_cpus;
396 struct acpi_buffer param = {
397 .length = 4,
398 .pointer = (void *)&idle_cpus,
399 };
400
401 mutex_lock(&isolated_cpus_lock);
402 num_cpus = acpi_pad_pur(handle);
403 if (num_cpus < 0) {
404 mutex_unlock(&isolated_cpus_lock);
405 return;
406 }
407 acpi_pad_idle_cpus(num_cpus);
408 idle_cpus = acpi_pad_idle_cpus_num();
409 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
410 mutex_unlock(&isolated_cpus_lock);
411}
412
413static void acpi_pad_notify(acpi_handle handle, u32 event,
414 void *data)
415{
416 struct acpi_device *device = data;
417
418 switch (event) {
419 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
420 acpi_pad_handle_notify(handle);
421 acpi_bus_generate_netlink_event(device->pnp.device_class,
422 dev_name(&device->dev), event, 0);
423 break;
424 default:
425 pr_warn("Unsupported event [0x%x]\n", event);
426 break;
427 }
428}
429
430static int acpi_pad_add(struct acpi_device *device)
431{
432 acpi_status status;
433
434 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
435 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
436
437 if (acpi_pad_add_sysfs(device))
438 return -ENODEV;
439
440 status = acpi_install_notify_handler(device->handle,
441 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
442 if (ACPI_FAILURE(status)) {
443 acpi_pad_remove_sysfs(device);
444 return -ENODEV;
445 }
446
447 return 0;
448}
449
450static int acpi_pad_remove(struct acpi_device *device)
451{
452 mutex_lock(&isolated_cpus_lock);
453 acpi_pad_idle_cpus(0);
454 mutex_unlock(&isolated_cpus_lock);
455
456 acpi_remove_notify_handler(device->handle,
457 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
458 acpi_pad_remove_sysfs(device);
459 return 0;
460}
461
462static const struct acpi_device_id pad_device_ids[] = {
463 {"ACPI000C", 0},
464 {"", 0},
465};
466MODULE_DEVICE_TABLE(acpi, pad_device_ids);
467
468static struct acpi_driver acpi_pad_driver = {
469 .name = "processor_aggregator",
470 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
471 .ids = pad_device_ids,
472 .ops = {
473 .add = acpi_pad_add,
474 .remove = acpi_pad_remove,
475 },
476};
477
478static int __init acpi_pad_init(void)
479{
480 power_saving_mwait_init();
481 if (power_saving_mwait_eax == 0)
482 return -EINVAL;
483
484 return acpi_bus_register_driver(&acpi_pad_driver);
485}
486
487static void __exit acpi_pad_exit(void)
488{
489 acpi_bus_unregister_driver(&acpi_pad_driver);
490}
491
492module_init(acpi_pad_init);
493module_exit(acpi_pad_exit);
494MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
495MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
496MODULE_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 <linux/platform_device.h>
22#include <asm/mwait.h>
23#include <xen/xen.h>
24
25#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
26#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
27#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
28static DEFINE_MUTEX(isolated_cpus_lock);
29static DEFINE_MUTEX(round_robin_lock);
30
31static unsigned long power_saving_mwait_eax;
32
33static unsigned char tsc_detected_unstable;
34static unsigned char tsc_marked_unstable;
35
36static void power_saving_mwait_init(void)
37{
38 unsigned int eax, ebx, ecx, edx;
39 unsigned int highest_cstate = 0;
40 unsigned int highest_subcstate = 0;
41 int i;
42
43 if (!boot_cpu_has(X86_FEATURE_MWAIT))
44 return;
45 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
46 return;
47
48 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
49
50 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
51 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
52 return;
53
54 edx >>= MWAIT_SUBSTATE_SIZE;
55 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
56 if (edx & MWAIT_SUBSTATE_MASK) {
57 highest_cstate = i;
58 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
59 }
60 }
61 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
62 (highest_subcstate - 1);
63
64#if defined(CONFIG_X86)
65 switch (boot_cpu_data.x86_vendor) {
66 case X86_VENDOR_HYGON:
67 case X86_VENDOR_AMD:
68 case X86_VENDOR_INTEL:
69 case X86_VENDOR_ZHAOXIN:
70 case X86_VENDOR_CENTAUR:
71 /*
72 * AMD Fam10h TSC will tick in all
73 * C/P/S0/S1 states when this bit is set.
74 */
75 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
76 tsc_detected_unstable = 1;
77 break;
78 default:
79 /* TSC could halt in idle */
80 tsc_detected_unstable = 1;
81 }
82#endif
83}
84
85static unsigned long cpu_weight[NR_CPUS];
86static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
87static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
88static void round_robin_cpu(unsigned int tsk_index)
89{
90 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
91 cpumask_var_t tmp;
92 int cpu;
93 unsigned long min_weight = -1;
94 unsigned long preferred_cpu;
95
96 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
97 return;
98
99 mutex_lock(&round_robin_lock);
100 cpumask_clear(tmp);
101 for_each_cpu(cpu, pad_busy_cpus)
102 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
103 cpumask_andnot(tmp, cpu_online_mask, tmp);
104 /* avoid HT siblings if possible */
105 if (cpumask_empty(tmp))
106 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
107 if (cpumask_empty(tmp)) {
108 mutex_unlock(&round_robin_lock);
109 free_cpumask_var(tmp);
110 return;
111 }
112 for_each_cpu(cpu, tmp) {
113 if (cpu_weight[cpu] < min_weight) {
114 min_weight = cpu_weight[cpu];
115 preferred_cpu = cpu;
116 }
117 }
118
119 if (tsk_in_cpu[tsk_index] != -1)
120 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
121 tsk_in_cpu[tsk_index] = preferred_cpu;
122 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
123 cpu_weight[preferred_cpu]++;
124 mutex_unlock(&round_robin_lock);
125
126 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
127
128 free_cpumask_var(tmp);
129}
130
131static void exit_round_robin(unsigned int tsk_index)
132{
133 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
134
135 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
136 tsk_in_cpu[tsk_index] = -1;
137}
138
139static unsigned int idle_pct = 5; /* percentage */
140static unsigned int round_robin_time = 1; /* second */
141static int power_saving_thread(void *data)
142{
143 int do_sleep;
144 unsigned int tsk_index = (unsigned long)data;
145 u64 last_jiffies = 0;
146
147 sched_set_fifo_low(current);
148
149 while (!kthread_should_stop()) {
150 unsigned long expire_time;
151
152 /* round robin to cpus */
153 expire_time = last_jiffies + round_robin_time * HZ;
154 if (time_before(expire_time, jiffies)) {
155 last_jiffies = jiffies;
156 round_robin_cpu(tsk_index);
157 }
158
159 do_sleep = 0;
160
161 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
162
163 while (!need_resched()) {
164 if (tsc_detected_unstable && !tsc_marked_unstable) {
165 /* TSC could halt in idle, so notify users */
166 mark_tsc_unstable("TSC halts in idle");
167 tsc_marked_unstable = 1;
168 }
169 local_irq_disable();
170
171 perf_lopwr_cb(true);
172
173 tick_broadcast_enable();
174 tick_broadcast_enter();
175 stop_critical_timings();
176
177 mwait_idle_with_hints(power_saving_mwait_eax, 1);
178
179 start_critical_timings();
180 tick_broadcast_exit();
181
182 perf_lopwr_cb(false);
183
184 local_irq_enable();
185
186 if (time_before(expire_time, jiffies)) {
187 do_sleep = 1;
188 break;
189 }
190 }
191
192 /*
193 * current sched_rt has threshold for rt task running time.
194 * When a rt task uses 95% CPU time, the rt thread will be
195 * scheduled out for 5% CPU time to not starve other tasks. But
196 * the mechanism only works when all CPUs have RT task running,
197 * as if one CPU hasn't RT task, RT task from other CPUs will
198 * borrow CPU time from this CPU and cause RT task use > 95%
199 * CPU time. To make 'avoid starvation' work, takes a nap here.
200 */
201 if (unlikely(do_sleep))
202 schedule_timeout_killable(HZ * idle_pct / 100);
203
204 /* If an external event has set the need_resched flag, then
205 * we need to deal with it, or this loop will continue to
206 * spin without calling __mwait().
207 */
208 if (unlikely(need_resched()))
209 schedule();
210 }
211
212 exit_round_robin(tsk_index);
213 return 0;
214}
215
216static struct task_struct *ps_tsks[NR_CPUS];
217static unsigned int ps_tsk_num;
218static int create_power_saving_task(void)
219{
220 int rc;
221
222 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
223 (void *)(unsigned long)ps_tsk_num,
224 "acpi_pad/%d", ps_tsk_num);
225
226 if (IS_ERR(ps_tsks[ps_tsk_num])) {
227 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
228 ps_tsks[ps_tsk_num] = NULL;
229 } else {
230 rc = 0;
231 ps_tsk_num++;
232 }
233
234 return rc;
235}
236
237static void destroy_power_saving_task(void)
238{
239 if (ps_tsk_num > 0) {
240 ps_tsk_num--;
241 kthread_stop(ps_tsks[ps_tsk_num]);
242 ps_tsks[ps_tsk_num] = NULL;
243 }
244}
245
246static void set_power_saving_task_num(unsigned int num)
247{
248 if (num > ps_tsk_num) {
249 while (ps_tsk_num < num) {
250 if (create_power_saving_task())
251 return;
252 }
253 } else if (num < ps_tsk_num) {
254 while (ps_tsk_num > num)
255 destroy_power_saving_task();
256 }
257}
258
259static void acpi_pad_idle_cpus(unsigned int num_cpus)
260{
261 cpus_read_lock();
262
263 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
264 set_power_saving_task_num(num_cpus);
265
266 cpus_read_unlock();
267}
268
269static uint32_t acpi_pad_idle_cpus_num(void)
270{
271 return ps_tsk_num;
272}
273
274static ssize_t rrtime_store(struct device *dev,
275 struct device_attribute *attr, const char *buf, size_t count)
276{
277 unsigned long num;
278
279 if (kstrtoul(buf, 0, &num))
280 return -EINVAL;
281 if (num < 1 || num >= 100)
282 return -EINVAL;
283 mutex_lock(&isolated_cpus_lock);
284 round_robin_time = num;
285 mutex_unlock(&isolated_cpus_lock);
286 return count;
287}
288
289static ssize_t rrtime_show(struct device *dev,
290 struct device_attribute *attr, char *buf)
291{
292 return sysfs_emit(buf, "%d\n", round_robin_time);
293}
294static DEVICE_ATTR_RW(rrtime);
295
296static ssize_t idlepct_store(struct device *dev,
297 struct device_attribute *attr, const char *buf, size_t count)
298{
299 unsigned long num;
300
301 if (kstrtoul(buf, 0, &num))
302 return -EINVAL;
303 if (num < 1 || num >= 100)
304 return -EINVAL;
305 mutex_lock(&isolated_cpus_lock);
306 idle_pct = num;
307 mutex_unlock(&isolated_cpus_lock);
308 return count;
309}
310
311static ssize_t idlepct_show(struct device *dev,
312 struct device_attribute *attr, char *buf)
313{
314 return sysfs_emit(buf, "%d\n", idle_pct);
315}
316static DEVICE_ATTR_RW(idlepct);
317
318static ssize_t idlecpus_store(struct device *dev,
319 struct device_attribute *attr, const char *buf, size_t count)
320{
321 unsigned long num;
322
323 if (kstrtoul(buf, 0, &num))
324 return -EINVAL;
325 mutex_lock(&isolated_cpus_lock);
326 acpi_pad_idle_cpus(num);
327 mutex_unlock(&isolated_cpus_lock);
328 return count;
329}
330
331static ssize_t idlecpus_show(struct device *dev,
332 struct device_attribute *attr, char *buf)
333{
334 return cpumap_print_to_pagebuf(false, buf,
335 to_cpumask(pad_busy_cpus_bits));
336}
337
338static DEVICE_ATTR_RW(idlecpus);
339
340static struct attribute *acpi_pad_attrs[] = {
341 &dev_attr_idlecpus.attr,
342 &dev_attr_idlepct.attr,
343 &dev_attr_rrtime.attr,
344 NULL
345};
346
347ATTRIBUTE_GROUPS(acpi_pad);
348
349/*
350 * Query firmware how many CPUs should be idle
351 * return -1 on failure
352 */
353static int acpi_pad_pur(acpi_handle handle)
354{
355 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
356 union acpi_object *package;
357 int num = -1;
358
359 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
360 return num;
361
362 if (!buffer.length || !buffer.pointer)
363 return num;
364
365 package = buffer.pointer;
366
367 if (package->type == ACPI_TYPE_PACKAGE &&
368 package->package.count == 2 &&
369 package->package.elements[0].integer.value == 1) /* rev 1 */
370
371 num = package->package.elements[1].integer.value;
372
373 kfree(buffer.pointer);
374 return num;
375}
376
377static void acpi_pad_handle_notify(acpi_handle handle)
378{
379 int num_cpus;
380 uint32_t idle_cpus;
381 struct acpi_buffer param = {
382 .length = 4,
383 .pointer = (void *)&idle_cpus,
384 };
385
386 mutex_lock(&isolated_cpus_lock);
387 num_cpus = acpi_pad_pur(handle);
388 if (num_cpus < 0) {
389 mutex_unlock(&isolated_cpus_lock);
390 return;
391 }
392 acpi_pad_idle_cpus(num_cpus);
393 idle_cpus = acpi_pad_idle_cpus_num();
394 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
395 mutex_unlock(&isolated_cpus_lock);
396}
397
398static void acpi_pad_notify(acpi_handle handle, u32 event,
399 void *data)
400{
401 struct acpi_device *adev = data;
402
403 switch (event) {
404 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
405 acpi_pad_handle_notify(handle);
406 acpi_bus_generate_netlink_event(adev->pnp.device_class,
407 dev_name(&adev->dev), event, 0);
408 break;
409 default:
410 pr_warn("Unsupported event [0x%x]\n", event);
411 break;
412 }
413}
414
415static int acpi_pad_probe(struct platform_device *pdev)
416{
417 struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
418 acpi_status status;
419
420 strcpy(acpi_device_name(adev), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
421 strcpy(acpi_device_class(adev), ACPI_PROCESSOR_AGGREGATOR_CLASS);
422
423 status = acpi_install_notify_handler(adev->handle,
424 ACPI_DEVICE_NOTIFY, acpi_pad_notify, adev);
425
426 if (ACPI_FAILURE(status))
427 return -ENODEV;
428
429 return 0;
430}
431
432static void acpi_pad_remove(struct platform_device *pdev)
433{
434 struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
435
436 mutex_lock(&isolated_cpus_lock);
437 acpi_pad_idle_cpus(0);
438 mutex_unlock(&isolated_cpus_lock);
439
440 acpi_remove_notify_handler(adev->handle,
441 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
442}
443
444static const struct acpi_device_id pad_device_ids[] = {
445 {"ACPI000C", 0},
446 {"", 0},
447};
448MODULE_DEVICE_TABLE(acpi, pad_device_ids);
449
450static struct platform_driver acpi_pad_driver = {
451 .probe = acpi_pad_probe,
452 .remove_new = acpi_pad_remove,
453 .driver = {
454 .dev_groups = acpi_pad_groups,
455 .name = "processor_aggregator",
456 .acpi_match_table = pad_device_ids,
457 },
458};
459
460static int __init acpi_pad_init(void)
461{
462 /* Xen ACPI PAD is used when running as Xen Dom0. */
463 if (xen_initial_domain())
464 return -ENODEV;
465
466 power_saving_mwait_init();
467 if (power_saving_mwait_eax == 0)
468 return -EINVAL;
469
470 return platform_driver_register(&acpi_pad_driver);
471}
472
473static void __exit acpi_pad_exit(void)
474{
475 platform_driver_unregister(&acpi_pad_driver);
476}
477
478module_init(acpi_pad_init);
479module_exit(acpi_pad_exit);
480MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
481MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
482MODULE_LICENSE("GPL");