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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/*
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 <uapi/linux/sched/types.h>
24#include <linux/freezer.h>
25#include <linux/cpu.h>
26#include <linux/tick.h>
27#include <linux/slab.h>
28#include <linux/acpi.h>
29#include <asm/mwait.h>
30#include <xen/xen.h>
31
32#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
33#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
34#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
35static DEFINE_MUTEX(isolated_cpus_lock);
36static DEFINE_MUTEX(round_robin_lock);
37
38static unsigned long power_saving_mwait_eax;
39
40static unsigned char tsc_detected_unstable;
41static unsigned char tsc_marked_unstable;
42
43static void power_saving_mwait_init(void)
44{
45 unsigned int eax, ebx, ecx, edx;
46 unsigned int highest_cstate = 0;
47 unsigned int highest_subcstate = 0;
48 int i;
49
50 if (!boot_cpu_has(X86_FEATURE_MWAIT))
51 return;
52 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
53 return;
54
55 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
56
57 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
58 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
59 return;
60
61 edx >>= MWAIT_SUBSTATE_SIZE;
62 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
63 if (edx & MWAIT_SUBSTATE_MASK) {
64 highest_cstate = i;
65 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
66 }
67 }
68 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
69 (highest_subcstate - 1);
70
71#if defined(CONFIG_X86)
72 switch (boot_cpu_data.x86_vendor) {
73 case X86_VENDOR_AMD:
74 case X86_VENDOR_INTEL:
75 /*
76 * AMD Fam10h TSC will tick in all
77 * C/P/S0/S1 states when this bit is set.
78 */
79 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
80 tsc_detected_unstable = 1;
81 break;
82 default:
83 /* TSC could halt in idle */
84 tsc_detected_unstable = 1;
85 }
86#endif
87}
88
89static unsigned long cpu_weight[NR_CPUS];
90static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
91static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
92static void round_robin_cpu(unsigned int tsk_index)
93{
94 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
95 cpumask_var_t tmp;
96 int cpu;
97 unsigned long min_weight = -1;
98 unsigned long uninitialized_var(preferred_cpu);
99
100 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
101 return;
102
103 mutex_lock(&round_robin_lock);
104 cpumask_clear(tmp);
105 for_each_cpu(cpu, pad_busy_cpus)
106 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
107 cpumask_andnot(tmp, cpu_online_mask, tmp);
108 /* avoid HT sibilings if possible */
109 if (cpumask_empty(tmp))
110 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
111 if (cpumask_empty(tmp)) {
112 mutex_unlock(&round_robin_lock);
113 free_cpumask_var(tmp);
114 return;
115 }
116 for_each_cpu(cpu, tmp) {
117 if (cpu_weight[cpu] < min_weight) {
118 min_weight = cpu_weight[cpu];
119 preferred_cpu = cpu;
120 }
121 }
122
123 if (tsk_in_cpu[tsk_index] != -1)
124 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
125 tsk_in_cpu[tsk_index] = preferred_cpu;
126 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
127 cpu_weight[preferred_cpu]++;
128 mutex_unlock(&round_robin_lock);
129
130 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
131
132 free_cpumask_var(tmp);
133}
134
135static void exit_round_robin(unsigned int tsk_index)
136{
137 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
138 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
139 tsk_in_cpu[tsk_index] = -1;
140}
141
142static unsigned int idle_pct = 5; /* percentage */
143static unsigned int round_robin_time = 1; /* second */
144static int power_saving_thread(void *data)
145{
146 struct sched_param param = {.sched_priority = 1};
147 int do_sleep;
148 unsigned int tsk_index = (unsigned long)data;
149 u64 last_jiffies = 0;
150
151 sched_setscheduler(current, SCHED_RR, ¶m);
152
153 while (!kthread_should_stop()) {
154 unsigned long expire_time;
155
156 /* round robin to cpus */
157 expire_time = last_jiffies + round_robin_time * HZ;
158 if (time_before(expire_time, jiffies)) {
159 last_jiffies = jiffies;
160 round_robin_cpu(tsk_index);
161 }
162
163 do_sleep = 0;
164
165 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
166
167 while (!need_resched()) {
168 if (tsc_detected_unstable && !tsc_marked_unstable) {
169 /* TSC could halt in idle, so notify users */
170 mark_tsc_unstable("TSC halts in idle");
171 tsc_marked_unstable = 1;
172 }
173 local_irq_disable();
174 tick_broadcast_enable();
175 tick_broadcast_enter();
176 stop_critical_timings();
177
178 mwait_idle_with_hints(power_saving_mwait_eax, 1);
179
180 start_critical_timings();
181 tick_broadcast_exit();
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 get_online_cpus();
260
261 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
262 set_power_saving_task_num(num_cpus);
263
264 put_online_cpus();
265}
266
267static uint32_t acpi_pad_idle_cpus_num(void)
268{
269 return ps_tsk_num;
270}
271
272static ssize_t acpi_pad_rrtime_store(struct device *dev,
273 struct device_attribute *attr, const char *buf, size_t count)
274{
275 unsigned long num;
276 if (kstrtoul(buf, 0, &num))
277 return -EINVAL;
278 if (num < 1 || num >= 100)
279 return -EINVAL;
280 mutex_lock(&isolated_cpus_lock);
281 round_robin_time = num;
282 mutex_unlock(&isolated_cpus_lock);
283 return count;
284}
285
286static ssize_t acpi_pad_rrtime_show(struct device *dev,
287 struct device_attribute *attr, char *buf)
288{
289 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
290}
291static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
292 acpi_pad_rrtime_show,
293 acpi_pad_rrtime_store);
294
295static ssize_t acpi_pad_idlepct_store(struct device *dev,
296 struct device_attribute *attr, const char *buf, size_t count)
297{
298 unsigned long num;
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 acpi_pad_idlepct_show(struct device *dev,
310 struct device_attribute *attr, char *buf)
311{
312 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
313}
314static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
315 acpi_pad_idlepct_show,
316 acpi_pad_idlepct_store);
317
318static ssize_t acpi_pad_idlecpus_store(struct device *dev,
319 struct device_attribute *attr, const char *buf, size_t count)
320{
321 unsigned long num;
322 if (kstrtoul(buf, 0, &num))
323 return -EINVAL;
324 mutex_lock(&isolated_cpus_lock);
325 acpi_pad_idle_cpus(num);
326 mutex_unlock(&isolated_cpus_lock);
327 return count;
328}
329
330static ssize_t acpi_pad_idlecpus_show(struct device *dev,
331 struct device_attribute *attr, char *buf)
332{
333 return cpumap_print_to_pagebuf(false, buf,
334 to_cpumask(pad_busy_cpus_bits));
335}
336
337static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
338 acpi_pad_idlecpus_show,
339 acpi_pad_idlecpus_store);
340
341static int acpi_pad_add_sysfs(struct acpi_device *device)
342{
343 int result;
344
345 result = device_create_file(&device->dev, &dev_attr_idlecpus);
346 if (result)
347 return -ENODEV;
348 result = device_create_file(&device->dev, &dev_attr_idlepct);
349 if (result) {
350 device_remove_file(&device->dev, &dev_attr_idlecpus);
351 return -ENODEV;
352 }
353 result = device_create_file(&device->dev, &dev_attr_rrtime);
354 if (result) {
355 device_remove_file(&device->dev, &dev_attr_idlecpus);
356 device_remove_file(&device->dev, &dev_attr_idlepct);
357 return -ENODEV;
358 }
359 return 0;
360}
361
362static void acpi_pad_remove_sysfs(struct acpi_device *device)
363{
364 device_remove_file(&device->dev, &dev_attr_idlecpus);
365 device_remove_file(&device->dev, &dev_attr_idlepct);
366 device_remove_file(&device->dev, &dev_attr_rrtime);
367}
368
369/*
370 * Query firmware how many CPUs should be idle
371 * return -1 on failure
372 */
373static int acpi_pad_pur(acpi_handle handle)
374{
375 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
376 union acpi_object *package;
377 int num = -1;
378
379 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
380 return num;
381
382 if (!buffer.length || !buffer.pointer)
383 return num;
384
385 package = buffer.pointer;
386
387 if (package->type == ACPI_TYPE_PACKAGE &&
388 package->package.count == 2 &&
389 package->package.elements[0].integer.value == 1) /* rev 1 */
390
391 num = package->package.elements[1].integer.value;
392
393 kfree(buffer.pointer);
394 return num;
395}
396
397static void acpi_pad_handle_notify(acpi_handle handle)
398{
399 int num_cpus;
400 uint32_t idle_cpus;
401 struct acpi_buffer param = {
402 .length = 4,
403 .pointer = (void *)&idle_cpus,
404 };
405
406 mutex_lock(&isolated_cpus_lock);
407 num_cpus = acpi_pad_pur(handle);
408 if (num_cpus < 0) {
409 mutex_unlock(&isolated_cpus_lock);
410 return;
411 }
412 acpi_pad_idle_cpus(num_cpus);
413 idle_cpus = acpi_pad_idle_cpus_num();
414 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
415 mutex_unlock(&isolated_cpus_lock);
416}
417
418static void acpi_pad_notify(acpi_handle handle, u32 event,
419 void *data)
420{
421 struct acpi_device *device = data;
422
423 switch (event) {
424 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
425 acpi_pad_handle_notify(handle);
426 acpi_bus_generate_netlink_event(device->pnp.device_class,
427 dev_name(&device->dev), event, 0);
428 break;
429 default:
430 pr_warn("Unsupported event [0x%x]\n", event);
431 break;
432 }
433}
434
435static int acpi_pad_add(struct acpi_device *device)
436{
437 acpi_status status;
438
439 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
440 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
441
442 if (acpi_pad_add_sysfs(device))
443 return -ENODEV;
444
445 status = acpi_install_notify_handler(device->handle,
446 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
447 if (ACPI_FAILURE(status)) {
448 acpi_pad_remove_sysfs(device);
449 return -ENODEV;
450 }
451
452 return 0;
453}
454
455static int acpi_pad_remove(struct acpi_device *device)
456{
457 mutex_lock(&isolated_cpus_lock);
458 acpi_pad_idle_cpus(0);
459 mutex_unlock(&isolated_cpus_lock);
460
461 acpi_remove_notify_handler(device->handle,
462 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
463 acpi_pad_remove_sysfs(device);
464 return 0;
465}
466
467static const struct acpi_device_id pad_device_ids[] = {
468 {"ACPI000C", 0},
469 {"", 0},
470};
471MODULE_DEVICE_TABLE(acpi, pad_device_ids);
472
473static struct acpi_driver acpi_pad_driver = {
474 .name = "processor_aggregator",
475 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
476 .ids = pad_device_ids,
477 .ops = {
478 .add = acpi_pad_add,
479 .remove = acpi_pad_remove,
480 },
481};
482
483static int __init acpi_pad_init(void)
484{
485 /* Xen ACPI PAD is used when running as Xen Dom0. */
486 if (xen_initial_domain())
487 return -ENODEV;
488
489 power_saving_mwait_init();
490 if (power_saving_mwait_eax == 0)
491 return -EINVAL;
492
493 return acpi_bus_register_driver(&acpi_pad_driver);
494}
495
496static void __exit acpi_pad_exit(void)
497{
498 acpi_bus_unregister_driver(&acpi_pad_driver);
499}
500
501module_init(acpi_pad_init);
502module_exit(acpi_pad_exit);
503MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
504MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
505MODULE_LICENSE("GPL");