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1c33be57 NP |
1 | /* |
2 | * arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver | |
3 | * | |
4 | * Created by: Nicolas Pitre, March 2012 | |
5 | * Copyright: (C) 2012-2013 Linaro Limited | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
0577fee2 | 12 | #include <linux/atomic.h> |
1c33be57 NP |
13 | #include <linux/init.h> |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/sched.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/cpu_pm.h> | |
71ce1dee | 19 | #include <linux/cpu.h> |
3f09d479 | 20 | #include <linux/cpumask.h> |
71ce1dee NP |
21 | #include <linux/kthread.h> |
22 | #include <linux/wait.h> | |
1bfbddb6 | 23 | #include <linux/time.h> |
3f09d479 LP |
24 | #include <linux/clockchips.h> |
25 | #include <linux/hrtimer.h> | |
26 | #include <linux/tick.h> | |
491990e2 | 27 | #include <linux/notifier.h> |
1c33be57 | 28 | #include <linux/mm.h> |
c0f43751 | 29 | #include <linux/mutex.h> |
b09bbe5b | 30 | #include <linux/smp.h> |
0577fee2 | 31 | #include <linux/spinlock.h> |
1c33be57 | 32 | #include <linux/string.h> |
6b7437ae | 33 | #include <linux/sysfs.h> |
1c33be57 | 34 | #include <linux/irqchip/arm-gic.h> |
c4821c05 | 35 | #include <linux/moduleparam.h> |
1c33be57 NP |
36 | |
37 | #include <asm/smp_plat.h> | |
1bfbddb6 | 38 | #include <asm/cputype.h> |
1c33be57 NP |
39 | #include <asm/suspend.h> |
40 | #include <asm/mcpm.h> | |
41 | #include <asm/bL_switcher.h> | |
42 | ||
1bfbddb6 DM |
43 | #define CREATE_TRACE_POINTS |
44 | #include <trace/events/power_cpu_migrate.h> | |
45 | ||
1c33be57 NP |
46 | |
47 | /* | |
48 | * Use our own MPIDR accessors as the generic ones in asm/cputype.h have | |
49 | * __attribute_const__ and we don't want the compiler to assume any | |
50 | * constness here as the value _does_ change along some code paths. | |
51 | */ | |
52 | ||
53 | static int read_mpidr(void) | |
54 | { | |
55 | unsigned int id; | |
56 | asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id)); | |
57 | return id & MPIDR_HWID_BITMASK; | |
58 | } | |
59 | ||
60 | /* | |
61 | * bL switcher core code. | |
62 | */ | |
63 | ||
108a9640 | 64 | static void bL_do_switch(void *_arg) |
1c33be57 | 65 | { |
38c35d4f | 66 | unsigned ib_mpidr, ib_cpu, ib_cluster; |
108a9640 | 67 | long volatile handshake, **handshake_ptr = _arg; |
1c33be57 | 68 | |
1c33be57 NP |
69 | pr_debug("%s\n", __func__); |
70 | ||
38c35d4f NP |
71 | ib_mpidr = cpu_logical_map(smp_processor_id()); |
72 | ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); | |
73 | ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); | |
1c33be57 | 74 | |
108a9640 NP |
75 | /* Advertise our handshake location */ |
76 | if (handshake_ptr) { | |
77 | handshake = 0; | |
78 | *handshake_ptr = &handshake; | |
79 | } else | |
80 | handshake = -1; | |
81 | ||
1c33be57 NP |
82 | /* |
83 | * Our state has been saved at this point. Let's release our | |
84 | * inbound CPU. | |
85 | */ | |
38c35d4f | 86 | mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume); |
1c33be57 NP |
87 | sev(); |
88 | ||
89 | /* | |
90 | * From this point, we must assume that our counterpart CPU might | |
91 | * have taken over in its parallel world already, as if execution | |
92 | * just returned from cpu_suspend(). It is therefore important to | |
93 | * be very careful not to make any change the other guy is not | |
94 | * expecting. This is why we need stack isolation. | |
95 | * | |
96 | * Fancy under cover tasks could be performed here. For now | |
97 | * we have none. | |
98 | */ | |
99 | ||
108a9640 NP |
100 | /* |
101 | * Let's wait until our inbound is alive. | |
102 | */ | |
103 | while (!handshake) { | |
104 | wfe(); | |
105 | smp_mb(); | |
106 | } | |
107 | ||
1c33be57 NP |
108 | /* Let's put ourself down. */ |
109 | mcpm_cpu_power_down(); | |
110 | ||
111 | /* should never get here */ | |
112 | BUG(); | |
113 | } | |
114 | ||
115 | /* | |
c052de26 NP |
116 | * Stack isolation. To ensure 'current' remains valid, we just use another |
117 | * piece of our thread's stack space which should be fairly lightly used. | |
118 | * The selected area starts just above the thread_info structure located | |
119 | * at the very bottom of the stack, aligned to a cache line, and indexed | |
120 | * with the cluster number. | |
1c33be57 | 121 | */ |
c052de26 | 122 | #define STACK_SIZE 512 |
1c33be57 NP |
123 | extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); |
124 | static int bL_switchpoint(unsigned long _arg) | |
125 | { | |
126 | unsigned int mpidr = read_mpidr(); | |
1c33be57 | 127 | unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1); |
c052de26 | 128 | void *stack = current_thread_info() + 1; |
1c33be57 | 129 | stack = PTR_ALIGN(stack, L1_CACHE_BYTES); |
c052de26 | 130 | stack += clusterid * STACK_SIZE + STACK_SIZE; |
1c33be57 NP |
131 | call_with_stack(bL_do_switch, (void *)_arg, stack); |
132 | BUG(); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Generic switcher interface | |
137 | */ | |
138 | ||
ed96762e | 139 | static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS]; |
38c35d4f | 140 | static int bL_switcher_cpu_pairing[NR_CPUS]; |
ed96762e | 141 | |
1c33be57 NP |
142 | /* |
143 | * bL_switch_to - Switch to a specific cluster for the current CPU | |
144 | * @new_cluster_id: the ID of the cluster to switch to. | |
145 | * | |
146 | * This function must be called on the CPU to be switched. | |
147 | * Returns 0 on success, else a negative status code. | |
148 | */ | |
149 | static int bL_switch_to(unsigned int new_cluster_id) | |
150 | { | |
38c35d4f NP |
151 | unsigned int mpidr, this_cpu, that_cpu; |
152 | unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; | |
6137eba6 | 153 | struct completion inbound_alive; |
108a9640 | 154 | long volatile *handshake_ptr; |
6137eba6 | 155 | int ipi_nr, ret; |
1c33be57 | 156 | |
38c35d4f NP |
157 | this_cpu = smp_processor_id(); |
158 | ob_mpidr = read_mpidr(); | |
159 | ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0); | |
160 | ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1); | |
161 | BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr); | |
1c33be57 | 162 | |
38c35d4f | 163 | if (new_cluster_id == ob_cluster) |
1c33be57 NP |
164 | return 0; |
165 | ||
38c35d4f NP |
166 | that_cpu = bL_switcher_cpu_pairing[this_cpu]; |
167 | ib_mpidr = cpu_logical_map(that_cpu); | |
168 | ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); | |
169 | ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); | |
170 | ||
171 | pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n", | |
172 | this_cpu, ob_mpidr, ib_mpidr); | |
1c33be57 | 173 | |
6137eba6 NP |
174 | this_cpu = smp_processor_id(); |
175 | ||
1c33be57 | 176 | /* Close the gate for our entry vectors */ |
38c35d4f NP |
177 | mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL); |
178 | mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL); | |
1c33be57 | 179 | |
6137eba6 NP |
180 | /* Install our "inbound alive" notifier. */ |
181 | init_completion(&inbound_alive); | |
182 | ipi_nr = register_ipi_completion(&inbound_alive, this_cpu); | |
183 | ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]); | |
184 | mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr); | |
185 | ||
1c33be57 NP |
186 | /* |
187 | * Let's wake up the inbound CPU now in case it requires some delay | |
188 | * to come online, but leave it gated in our entry vector code. | |
189 | */ | |
38c35d4f | 190 | ret = mcpm_cpu_power_up(ib_cpu, ib_cluster); |
1c33be57 NP |
191 | if (ret) { |
192 | pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret); | |
193 | return ret; | |
194 | } | |
195 | ||
6137eba6 NP |
196 | /* |
197 | * Raise a SGI on the inbound CPU to make sure it doesn't stall | |
198 | * in a possible WFI, such as in bL_power_down(). | |
199 | */ | |
200 | gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0); | |
201 | ||
202 | /* | |
203 | * Wait for the inbound to come up. This allows for other | |
204 | * tasks to be scheduled in the mean time. | |
205 | */ | |
206 | wait_for_completion(&inbound_alive); | |
207 | mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0); | |
208 | ||
1c33be57 NP |
209 | /* |
210 | * From this point we are entering the switch critical zone | |
211 | * and can't take any interrupts anymore. | |
212 | */ | |
213 | local_irq_disable(); | |
214 | local_fiq_disable(); | |
41fa4215 | 215 | trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr); |
1c33be57 | 216 | |
1c33be57 | 217 | /* redirect GIC's SGIs to our counterpart */ |
38c35d4f | 218 | gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]); |
1c33be57 | 219 | |
7270d11c | 220 | tick_suspend_local(); |
3f09d479 | 221 | |
1c33be57 NP |
222 | ret = cpu_pm_enter(); |
223 | ||
224 | /* we can not tolerate errors at this point */ | |
225 | if (ret) | |
226 | panic("%s: cpu_pm_enter() returned %d\n", __func__, ret); | |
227 | ||
38c35d4f NP |
228 | /* Swap the physical CPUs in the logical map for this logical CPU. */ |
229 | cpu_logical_map(this_cpu) = ib_mpidr; | |
230 | cpu_logical_map(that_cpu) = ob_mpidr; | |
1c33be57 NP |
231 | |
232 | /* Let's do the actual CPU switch. */ | |
108a9640 | 233 | ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint); |
1c33be57 NP |
234 | if (ret > 0) |
235 | panic("%s: cpu_suspend() returned %d\n", __func__, ret); | |
236 | ||
237 | /* We are executing on the inbound CPU at this point */ | |
238 | mpidr = read_mpidr(); | |
38c35d4f NP |
239 | pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr); |
240 | BUG_ON(mpidr != ib_mpidr); | |
1c33be57 NP |
241 | |
242 | mcpm_cpu_powered_up(); | |
243 | ||
244 | ret = cpu_pm_exit(); | |
245 | ||
7270d11c | 246 | tick_resume_local(); |
3f09d479 | 247 | |
41fa4215 | 248 | trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr); |
1c33be57 NP |
249 | local_fiq_enable(); |
250 | local_irq_enable(); | |
251 | ||
108a9640 NP |
252 | *handshake_ptr = 1; |
253 | dsb_sev(); | |
254 | ||
1c33be57 NP |
255 | if (ret) |
256 | pr_err("%s exiting with error %d\n", __func__, ret); | |
257 | return ret; | |
258 | } | |
259 | ||
71ce1dee | 260 | struct bL_thread { |
0577fee2 | 261 | spinlock_t lock; |
71ce1dee NP |
262 | struct task_struct *task; |
263 | wait_queue_head_t wq; | |
264 | int wanted_cluster; | |
6b7437ae | 265 | struct completion started; |
0577fee2 DM |
266 | bL_switch_completion_handler completer; |
267 | void *completer_cookie; | |
1c33be57 NP |
268 | }; |
269 | ||
71ce1dee NP |
270 | static struct bL_thread bL_threads[NR_CPUS]; |
271 | ||
272 | static int bL_switcher_thread(void *arg) | |
273 | { | |
274 | struct bL_thread *t = arg; | |
275 | struct sched_param param = { .sched_priority = 1 }; | |
276 | int cluster; | |
0577fee2 DM |
277 | bL_switch_completion_handler completer; |
278 | void *completer_cookie; | |
71ce1dee NP |
279 | |
280 | sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); | |
6b7437ae | 281 | complete(&t->started); |
71ce1dee NP |
282 | |
283 | do { | |
284 | if (signal_pending(current)) | |
285 | flush_signals(current); | |
286 | wait_event_interruptible(t->wq, | |
287 | t->wanted_cluster != -1 || | |
288 | kthread_should_stop()); | |
0577fee2 DM |
289 | |
290 | spin_lock(&t->lock); | |
291 | cluster = t->wanted_cluster; | |
292 | completer = t->completer; | |
293 | completer_cookie = t->completer_cookie; | |
294 | t->wanted_cluster = -1; | |
295 | t->completer = NULL; | |
296 | spin_unlock(&t->lock); | |
297 | ||
298 | if (cluster != -1) { | |
71ce1dee | 299 | bL_switch_to(cluster); |
0577fee2 DM |
300 | |
301 | if (completer) | |
302 | completer(completer_cookie); | |
303 | } | |
71ce1dee NP |
304 | } while (!kthread_should_stop()); |
305 | ||
306 | return 0; | |
307 | } | |
308 | ||
6b7437ae | 309 | static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) |
1c33be57 | 310 | { |
71ce1dee NP |
311 | struct task_struct *task; |
312 | ||
313 | task = kthread_create_on_node(bL_switcher_thread, arg, | |
314 | cpu_to_node(cpu), "kswitcher_%d", cpu); | |
315 | if (!IS_ERR(task)) { | |
316 | kthread_bind(task, cpu); | |
317 | wake_up_process(task); | |
318 | } else | |
319 | pr_err("%s failed for CPU %d\n", __func__, cpu); | |
320 | return task; | |
1c33be57 NP |
321 | } |
322 | ||
323 | /* | |
0577fee2 DM |
324 | * bL_switch_request_cb - Switch to a specific cluster for the given CPU, |
325 | * with completion notification via a callback | |
1c33be57 NP |
326 | * |
327 | * @cpu: the CPU to switch | |
328 | * @new_cluster_id: the ID of the cluster to switch to. | |
0577fee2 DM |
329 | * @completer: switch completion callback. if non-NULL, |
330 | * @completer(@completer_cookie) will be called on completion of | |
331 | * the switch, in non-atomic context. | |
332 | * @completer_cookie: opaque context argument for @completer. | |
1c33be57 | 333 | * |
71ce1dee NP |
334 | * This function causes a cluster switch on the given CPU by waking up |
335 | * the appropriate switcher thread. This function may or may not return | |
336 | * before the switch has occurred. | |
0577fee2 DM |
337 | * |
338 | * If a @completer callback function is supplied, it will be called when | |
339 | * the switch is complete. This can be used to determine asynchronously | |
340 | * when the switch is complete, regardless of when bL_switch_request() | |
341 | * returns. When @completer is supplied, no new switch request is permitted | |
342 | * for the affected CPU until after the switch is complete, and @completer | |
343 | * has returned. | |
1c33be57 | 344 | */ |
0577fee2 DM |
345 | int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id, |
346 | bL_switch_completion_handler completer, | |
347 | void *completer_cookie) | |
1c33be57 | 348 | { |
71ce1dee | 349 | struct bL_thread *t; |
1c33be57 | 350 | |
71ce1dee NP |
351 | if (cpu >= ARRAY_SIZE(bL_threads)) { |
352 | pr_err("%s: cpu %d out of bounds\n", __func__, cpu); | |
353 | return -EINVAL; | |
1c33be57 | 354 | } |
1c33be57 | 355 | |
71ce1dee | 356 | t = &bL_threads[cpu]; |
0577fee2 | 357 | |
71ce1dee NP |
358 | if (IS_ERR(t->task)) |
359 | return PTR_ERR(t->task); | |
360 | if (!t->task) | |
361 | return -ESRCH; | |
362 | ||
0577fee2 DM |
363 | spin_lock(&t->lock); |
364 | if (t->completer) { | |
365 | spin_unlock(&t->lock); | |
366 | return -EBUSY; | |
367 | } | |
368 | t->completer = completer; | |
369 | t->completer_cookie = completer_cookie; | |
71ce1dee | 370 | t->wanted_cluster = new_cluster_id; |
0577fee2 | 371 | spin_unlock(&t->lock); |
71ce1dee NP |
372 | wake_up(&t->wq); |
373 | return 0; | |
1c33be57 | 374 | } |
0577fee2 | 375 | EXPORT_SYMBOL_GPL(bL_switch_request_cb); |
71ce1dee | 376 | |
9797a0e9 NP |
377 | /* |
378 | * Activation and configuration code. | |
379 | */ | |
380 | ||
c0f43751 | 381 | static DEFINE_MUTEX(bL_switcher_activation_lock); |
491990e2 | 382 | static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier); |
6b7437ae | 383 | static unsigned int bL_switcher_active; |
38c35d4f | 384 | static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS]; |
9797a0e9 NP |
385 | static cpumask_t bL_switcher_removed_logical_cpus; |
386 | ||
491990e2 DM |
387 | int bL_switcher_register_notifier(struct notifier_block *nb) |
388 | { | |
389 | return blocking_notifier_chain_register(&bL_activation_notifier, nb); | |
390 | } | |
391 | EXPORT_SYMBOL_GPL(bL_switcher_register_notifier); | |
392 | ||
393 | int bL_switcher_unregister_notifier(struct notifier_block *nb) | |
394 | { | |
395 | return blocking_notifier_chain_unregister(&bL_activation_notifier, nb); | |
396 | } | |
397 | EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier); | |
398 | ||
399 | static int bL_activation_notify(unsigned long val) | |
400 | { | |
401 | int ret; | |
402 | ||
403 | ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL); | |
404 | if (ret & NOTIFY_STOP_MASK) | |
405 | pr_err("%s: notifier chain failed with status 0x%x\n", | |
406 | __func__, ret); | |
407 | return notifier_to_errno(ret); | |
408 | } | |
409 | ||
6b7437ae | 410 | static void bL_switcher_restore_cpus(void) |
9797a0e9 NP |
411 | { |
412 | int i; | |
413 | ||
3f8517e7 NP |
414 | for_each_cpu(i, &bL_switcher_removed_logical_cpus) { |
415 | struct device *cpu_dev = get_cpu_device(i); | |
416 | int ret = device_online(cpu_dev); | |
417 | if (ret) | |
418 | dev_err(cpu_dev, "switcher: unable to restore CPU\n"); | |
419 | } | |
9797a0e9 NP |
420 | } |
421 | ||
6b7437ae | 422 | static int bL_switcher_halve_cpus(void) |
9797a0e9 | 423 | { |
38c35d4f NP |
424 | int i, j, cluster_0, gic_id, ret; |
425 | unsigned int cpu, cluster, mask; | |
426 | cpumask_t available_cpus; | |
9797a0e9 | 427 | |
38c35d4f NP |
428 | /* First pass to validate what we have */ |
429 | mask = 0; | |
9797a0e9 | 430 | for_each_online_cpu(i) { |
38c35d4f NP |
431 | cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); |
432 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
9797a0e9 NP |
433 | if (cluster >= 2) { |
434 | pr_err("%s: only dual cluster systems are supported\n", __func__); | |
435 | return -EINVAL; | |
436 | } | |
38c35d4f NP |
437 | if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER)) |
438 | return -EINVAL; | |
439 | mask |= (1 << cluster); | |
9797a0e9 | 440 | } |
38c35d4f NP |
441 | if (mask != 3) { |
442 | pr_err("%s: no CPU pairing possible\n", __func__); | |
9797a0e9 NP |
443 | return -EINVAL; |
444 | } | |
445 | ||
38c35d4f NP |
446 | /* |
447 | * Now let's do the pairing. We match each CPU with another CPU | |
448 | * from a different cluster. To get a uniform scheduling behavior | |
449 | * without fiddling with CPU topology and compute capacity data, | |
450 | * we'll use logical CPUs initially belonging to the same cluster. | |
451 | */ | |
452 | memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing)); | |
453 | cpumask_copy(&available_cpus, cpu_online_mask); | |
454 | cluster_0 = -1; | |
455 | for_each_cpu(i, &available_cpus) { | |
456 | int match = -1; | |
457 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
458 | if (cluster_0 == -1) | |
459 | cluster_0 = cluster; | |
460 | if (cluster != cluster_0) | |
461 | continue; | |
462 | cpumask_clear_cpu(i, &available_cpus); | |
463 | for_each_cpu(j, &available_cpus) { | |
464 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1); | |
9797a0e9 | 465 | /* |
38c35d4f NP |
466 | * Let's remember the last match to create "odd" |
467 | * pairings on purpose in order for other code not | |
468 | * to assume any relation between physical and | |
469 | * logical CPU numbers. | |
9797a0e9 | 470 | */ |
38c35d4f NP |
471 | if (cluster != cluster_0) |
472 | match = j; | |
473 | } | |
474 | if (match != -1) { | |
475 | bL_switcher_cpu_pairing[i] = match; | |
476 | cpumask_clear_cpu(match, &available_cpus); | |
477 | pr_info("CPU%d paired with CPU%d\n", i, match); | |
478 | } | |
479 | } | |
480 | ||
481 | /* | |
482 | * Now we disable the unwanted CPUs i.e. everything that has no | |
483 | * pairing information (that includes the pairing counterparts). | |
484 | */ | |
485 | cpumask_clear(&bL_switcher_removed_logical_cpus); | |
486 | for_each_online_cpu(i) { | |
487 | cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); | |
488 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
489 | ||
490 | /* Let's take note of the GIC ID for this CPU */ | |
491 | gic_id = gic_get_cpu_id(i); | |
492 | if (gic_id < 0) { | |
493 | pr_err("%s: bad GIC ID for CPU %d\n", __func__, i); | |
494 | bL_switcher_restore_cpus(); | |
495 | return -EINVAL; | |
496 | } | |
497 | bL_gic_id[cpu][cluster] = gic_id; | |
498 | pr_info("GIC ID for CPU %u cluster %u is %u\n", | |
499 | cpu, cluster, gic_id); | |
500 | ||
501 | if (bL_switcher_cpu_pairing[i] != -1) { | |
502 | bL_switcher_cpu_original_cluster[i] = cluster; | |
503 | continue; | |
9797a0e9 NP |
504 | } |
505 | ||
3f8517e7 | 506 | ret = device_offline(get_cpu_device(i)); |
9797a0e9 NP |
507 | if (ret) { |
508 | bL_switcher_restore_cpus(); | |
509 | return ret; | |
510 | } | |
511 | cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus); | |
512 | } | |
513 | ||
514 | return 0; | |
515 | } | |
516 | ||
d08e2e09 DM |
517 | /* Determine the logical CPU a given physical CPU is grouped on. */ |
518 | int bL_switcher_get_logical_index(u32 mpidr) | |
519 | { | |
520 | int cpu; | |
521 | ||
522 | if (!bL_switcher_active) | |
523 | return -EUNATCH; | |
524 | ||
525 | mpidr &= MPIDR_HWID_BITMASK; | |
526 | for_each_online_cpu(cpu) { | |
527 | int pairing = bL_switcher_cpu_pairing[cpu]; | |
528 | if (pairing == -1) | |
529 | continue; | |
530 | if ((mpidr == cpu_logical_map(cpu)) || | |
531 | (mpidr == cpu_logical_map(pairing))) | |
532 | return cpu; | |
533 | } | |
534 | return -EINVAL; | |
535 | } | |
536 | ||
b09bbe5b DM |
537 | static void bL_switcher_trace_trigger_cpu(void *__always_unused info) |
538 | { | |
41fa4215 | 539 | trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr()); |
b09bbe5b DM |
540 | } |
541 | ||
29064b88 | 542 | int bL_switcher_trace_trigger(void) |
b09bbe5b DM |
543 | { |
544 | int ret; | |
545 | ||
546 | preempt_disable(); | |
547 | ||
548 | bL_switcher_trace_trigger_cpu(NULL); | |
549 | ret = smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true); | |
550 | ||
551 | preempt_enable(); | |
552 | ||
553 | return ret; | |
554 | } | |
29064b88 | 555 | EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger); |
b09bbe5b | 556 | |
6b7437ae | 557 | static int bL_switcher_enable(void) |
71ce1dee | 558 | { |
9797a0e9 | 559 | int cpu, ret; |
71ce1dee | 560 | |
c0f43751 | 561 | mutex_lock(&bL_switcher_activation_lock); |
b0ced9d2 | 562 | lock_device_hotplug(); |
6b7437ae | 563 | if (bL_switcher_active) { |
b0ced9d2 | 564 | unlock_device_hotplug(); |
c0f43751 | 565 | mutex_unlock(&bL_switcher_activation_lock); |
6b7437ae | 566 | return 0; |
9797a0e9 NP |
567 | } |
568 | ||
6b7437ae NP |
569 | pr_info("big.LITTLE switcher initializing\n"); |
570 | ||
491990e2 DM |
571 | ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE); |
572 | if (ret) | |
573 | goto error; | |
574 | ||
9797a0e9 | 575 | ret = bL_switcher_halve_cpus(); |
491990e2 DM |
576 | if (ret) |
577 | goto error; | |
9797a0e9 | 578 | |
b09bbe5b DM |
579 | bL_switcher_trace_trigger(); |
580 | ||
71ce1dee NP |
581 | for_each_online_cpu(cpu) { |
582 | struct bL_thread *t = &bL_threads[cpu]; | |
0577fee2 | 583 | spin_lock_init(&t->lock); |
71ce1dee | 584 | init_waitqueue_head(&t->wq); |
6b7437ae | 585 | init_completion(&t->started); |
71ce1dee NP |
586 | t->wanted_cluster = -1; |
587 | t->task = bL_switcher_thread_create(cpu, t); | |
588 | } | |
6b7437ae NP |
589 | |
590 | bL_switcher_active = 1; | |
491990e2 | 591 | bL_activation_notify(BL_NOTIFY_POST_ENABLE); |
71ce1dee | 592 | pr_info("big.LITTLE switcher initialized\n"); |
491990e2 DM |
593 | goto out; |
594 | ||
595 | error: | |
596 | pr_warn("big.LITTLE switcher initialization failed\n"); | |
597 | bL_activation_notify(BL_NOTIFY_POST_DISABLE); | |
c0f43751 | 598 | |
491990e2 | 599 | out: |
b0ced9d2 | 600 | unlock_device_hotplug(); |
c0f43751 | 601 | mutex_unlock(&bL_switcher_activation_lock); |
491990e2 | 602 | return ret; |
71ce1dee NP |
603 | } |
604 | ||
6b7437ae NP |
605 | #ifdef CONFIG_SYSFS |
606 | ||
607 | static void bL_switcher_disable(void) | |
608 | { | |
38c35d4f | 609 | unsigned int cpu, cluster; |
6b7437ae NP |
610 | struct bL_thread *t; |
611 | struct task_struct *task; | |
612 | ||
c0f43751 | 613 | mutex_lock(&bL_switcher_activation_lock); |
b0ced9d2 | 614 | lock_device_hotplug(); |
491990e2 DM |
615 | |
616 | if (!bL_switcher_active) | |
617 | goto out; | |
618 | ||
619 | if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) { | |
620 | bL_activation_notify(BL_NOTIFY_POST_ENABLE); | |
621 | goto out; | |
6b7437ae | 622 | } |
491990e2 | 623 | |
6b7437ae NP |
624 | bL_switcher_active = 0; |
625 | ||
626 | /* | |
627 | * To deactivate the switcher, we must shut down the switcher | |
628 | * threads to prevent any other requests from being accepted. | |
629 | * Then, if the final cluster for given logical CPU is not the | |
630 | * same as the original one, we'll recreate a switcher thread | |
631 | * just for the purpose of switching the CPU back without any | |
632 | * possibility for interference from external requests. | |
633 | */ | |
634 | for_each_online_cpu(cpu) { | |
6b7437ae NP |
635 | t = &bL_threads[cpu]; |
636 | task = t->task; | |
637 | t->task = NULL; | |
638 | if (!task || IS_ERR(task)) | |
639 | continue; | |
640 | kthread_stop(task); | |
641 | /* no more switch may happen on this CPU at this point */ | |
642 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); | |
643 | if (cluster == bL_switcher_cpu_original_cluster[cpu]) | |
644 | continue; | |
645 | init_completion(&t->started); | |
646 | t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu]; | |
647 | task = bL_switcher_thread_create(cpu, t); | |
648 | if (!IS_ERR(task)) { | |
649 | wait_for_completion(&t->started); | |
650 | kthread_stop(task); | |
651 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); | |
652 | if (cluster == bL_switcher_cpu_original_cluster[cpu]) | |
653 | continue; | |
654 | } | |
655 | /* If execution gets here, we're in trouble. */ | |
656 | pr_crit("%s: unable to restore original cluster for CPU %d\n", | |
657 | __func__, cpu); | |
38c35d4f NP |
658 | pr_crit("%s: CPU %d can't be restored\n", |
659 | __func__, bL_switcher_cpu_pairing[cpu]); | |
660 | cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu], | |
661 | &bL_switcher_removed_logical_cpus); | |
6b7437ae NP |
662 | } |
663 | ||
664 | bL_switcher_restore_cpus(); | |
b09bbe5b DM |
665 | bL_switcher_trace_trigger(); |
666 | ||
491990e2 DM |
667 | bL_activation_notify(BL_NOTIFY_POST_DISABLE); |
668 | ||
669 | out: | |
b0ced9d2 | 670 | unlock_device_hotplug(); |
c0f43751 | 671 | mutex_unlock(&bL_switcher_activation_lock); |
6b7437ae NP |
672 | } |
673 | ||
674 | static ssize_t bL_switcher_active_show(struct kobject *kobj, | |
675 | struct kobj_attribute *attr, char *buf) | |
676 | { | |
677 | return sprintf(buf, "%u\n", bL_switcher_active); | |
678 | } | |
679 | ||
680 | static ssize_t bL_switcher_active_store(struct kobject *kobj, | |
681 | struct kobj_attribute *attr, const char *buf, size_t count) | |
682 | { | |
683 | int ret; | |
684 | ||
685 | switch (buf[0]) { | |
686 | case '0': | |
687 | bL_switcher_disable(); | |
688 | ret = 0; | |
689 | break; | |
690 | case '1': | |
691 | ret = bL_switcher_enable(); | |
692 | break; | |
693 | default: | |
694 | ret = -EINVAL; | |
695 | } | |
696 | ||
697 | return (ret >= 0) ? count : ret; | |
698 | } | |
699 | ||
b09bbe5b DM |
700 | static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj, |
701 | struct kobj_attribute *attr, const char *buf, size_t count) | |
702 | { | |
703 | int ret = bL_switcher_trace_trigger(); | |
704 | ||
705 | return ret ? ret : count; | |
706 | } | |
707 | ||
6b7437ae NP |
708 | static struct kobj_attribute bL_switcher_active_attr = |
709 | __ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store); | |
710 | ||
b09bbe5b DM |
711 | static struct kobj_attribute bL_switcher_trace_trigger_attr = |
712 | __ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store); | |
713 | ||
6b7437ae NP |
714 | static struct attribute *bL_switcher_attrs[] = { |
715 | &bL_switcher_active_attr.attr, | |
b09bbe5b | 716 | &bL_switcher_trace_trigger_attr.attr, |
6b7437ae NP |
717 | NULL, |
718 | }; | |
719 | ||
720 | static struct attribute_group bL_switcher_attr_group = { | |
721 | .attrs = bL_switcher_attrs, | |
722 | }; | |
723 | ||
724 | static struct kobject *bL_switcher_kobj; | |
725 | ||
726 | static int __init bL_switcher_sysfs_init(void) | |
727 | { | |
728 | int ret; | |
729 | ||
730 | bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj); | |
731 | if (!bL_switcher_kobj) | |
732 | return -ENOMEM; | |
733 | ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group); | |
734 | if (ret) | |
735 | kobject_put(bL_switcher_kobj); | |
736 | return ret; | |
737 | } | |
738 | ||
739 | #endif /* CONFIG_SYSFS */ | |
740 | ||
c0f43751 DM |
741 | bool bL_switcher_get_enabled(void) |
742 | { | |
743 | mutex_lock(&bL_switcher_activation_lock); | |
744 | ||
745 | return bL_switcher_active; | |
746 | } | |
747 | EXPORT_SYMBOL_GPL(bL_switcher_get_enabled); | |
748 | ||
749 | void bL_switcher_put_enabled(void) | |
750 | { | |
751 | mutex_unlock(&bL_switcher_activation_lock); | |
752 | } | |
753 | EXPORT_SYMBOL_GPL(bL_switcher_put_enabled); | |
754 | ||
27261435 NP |
755 | /* |
756 | * Veto any CPU hotplug operation on those CPUs we've removed | |
757 | * while the switcher is active. | |
758 | * We're just not ready to deal with that given the trickery involved. | |
759 | */ | |
760 | static int bL_switcher_hotplug_callback(struct notifier_block *nfb, | |
761 | unsigned long action, void *hcpu) | |
762 | { | |
763 | if (bL_switcher_active) { | |
764 | int pairing = bL_switcher_cpu_pairing[(unsigned long)hcpu]; | |
765 | switch (action & 0xf) { | |
766 | case CPU_UP_PREPARE: | |
767 | case CPU_DOWN_PREPARE: | |
768 | if (pairing == -1) | |
769 | return NOTIFY_BAD; | |
770 | } | |
771 | } | |
772 | return NOTIFY_DONE; | |
773 | } | |
774 | ||
c4821c05 NP |
775 | static bool no_bL_switcher; |
776 | core_param(no_bL_switcher, no_bL_switcher, bool, 0644); | |
777 | ||
6b7437ae NP |
778 | static int __init bL_switcher_init(void) |
779 | { | |
780 | int ret; | |
781 | ||
4530e4b6 NP |
782 | if (!mcpm_is_available()) |
783 | return -ENODEV; | |
6b7437ae | 784 | |
27261435 NP |
785 | cpu_notifier(bL_switcher_hotplug_callback, 0); |
786 | ||
c4821c05 NP |
787 | if (!no_bL_switcher) { |
788 | ret = bL_switcher_enable(); | |
789 | if (ret) | |
790 | return ret; | |
791 | } | |
6b7437ae NP |
792 | |
793 | #ifdef CONFIG_SYSFS | |
794 | ret = bL_switcher_sysfs_init(); | |
795 | if (ret) | |
796 | pr_err("%s: unable to create sysfs entry\n", __func__); | |
797 | #endif | |
798 | ||
799 | return 0; | |
800 | } | |
801 | ||
71ce1dee | 802 | late_initcall(bL_switcher_init); |