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