blob: 6eaddc47c43dfbd60f52b6d49c425acbd55cab62 [file] [log] [blame]
Nicolas Pitre1c33be52012-04-12 02:56:10 -04001/*
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
Dave Martin0577fee2013-05-22 19:08:16 +010012#include <linux/atomic.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040013#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>
Nicolas Pitre71ce1de2012-10-26 02:36:17 -040019#include <linux/cpu.h>
Lorenzo Pieralisi3f09d472012-05-16 15:55:54 +010020#include <linux/cpumask.h>
Nicolas Pitre71ce1de2012-10-26 02:36:17 -040021#include <linux/kthread.h>
22#include <linux/wait.h>
Dave Martin1bfbddb2012-05-14 17:40:07 +010023#include <linux/time.h>
Lorenzo Pieralisi3f09d472012-05-16 15:55:54 +010024#include <linux/clockchips.h>
25#include <linux/hrtimer.h>
26#include <linux/tick.h>
Dave Martin491990e2012-12-10 17:19:58 +000027#include <linux/notifier.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040028#include <linux/mm.h>
Dave Martinc0f43752012-12-10 17:19:57 +000029#include <linux/mutex.h>
Dave Martinb09bbe52013-02-06 15:45:23 +000030#include <linux/smp.h>
Dave Martin0577fee2013-05-22 19:08:16 +010031#include <linux/spinlock.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040032#include <linux/string.h>
Nicolas Pitre6b7437a2012-11-22 00:05:07 -050033#include <linux/sysfs.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040034#include <linux/irqchip/arm-gic.h>
Nicolas Pitrec4821c02012-11-22 13:33:35 -050035#include <linux/moduleparam.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040036
37#include <asm/smp_plat.h>
Dave Martin1bfbddb2012-05-14 17:40:07 +010038#include <asm/cputype.h>
Nicolas Pitre1c33be52012-04-12 02:56:10 -040039#include <asm/suspend.h>
40#include <asm/mcpm.h>
41#include <asm/bL_switcher.h>
42
Dave Martin1bfbddb2012-05-14 17:40:07 +010043#define CREATE_TRACE_POINTS
44#include <trace/events/power_cpu_migrate.h>
45
Nicolas Pitre1c33be52012-04-12 02:56:10 -040046
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
53static 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
Nicolas Pitre108a9642012-10-23 01:39:08 -040064static void bL_do_switch(void *_arg)
Nicolas Pitre1c33be52012-04-12 02:56:10 -040065{
Nicolas Pitre38c35d42013-06-13 23:42:46 -040066 unsigned ib_mpidr, ib_cpu, ib_cluster;
Nicolas Pitre108a9642012-10-23 01:39:08 -040067 long volatile handshake, **handshake_ptr = _arg;
Nicolas Pitre1c33be52012-04-12 02:56:10 -040068
Nicolas Pitre1c33be52012-04-12 02:56:10 -040069 pr_debug("%s\n", __func__);
70
Nicolas Pitre38c35d42013-06-13 23:42:46 -040071 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);
Nicolas Pitre1c33be52012-04-12 02:56:10 -040074
Nicolas Pitre108a9642012-10-23 01:39:08 -040075 /* Advertise our handshake location */
76 if (handshake_ptr) {
77 handshake = 0;
78 *handshake_ptr = &handshake;
79 } else
80 handshake = -1;
81
Nicolas Pitre1c33be52012-04-12 02:56:10 -040082 /*
83 * Our state has been saved at this point. Let's release our
84 * inbound CPU.
85 */
Nicolas Pitre38c35d42013-06-13 23:42:46 -040086 mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume);
Nicolas Pitre1c33be52012-04-12 02:56:10 -040087 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
Nicolas Pitre108a9642012-10-23 01:39:08 -0400100 /*
101 * Let's wait until our inbound is alive.
102 */
103 while (!handshake) {
104 wfe();
105 smp_mb();
106 }
107
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400108 /* Let's put ourself down. */
109 mcpm_cpu_power_down();
110
111 /* should never get here */
112 BUG();
113}
114
115/*
Nicolas Pitrec052de22012-11-27 15:55:33 -0500116 * 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.
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400121 */
Nicolas Pitrec052de22012-11-27 15:55:33 -0500122#define STACK_SIZE 512
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400123extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
124static int bL_switchpoint(unsigned long _arg)
125{
126 unsigned int mpidr = read_mpidr();
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400127 unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
Nicolas Pitrec052de22012-11-27 15:55:33 -0500128 void *stack = current_thread_info() + 1;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400129 stack = PTR_ALIGN(stack, L1_CACHE_BYTES);
Nicolas Pitrec052de22012-11-27 15:55:33 -0500130 stack += clusterid * STACK_SIZE + STACK_SIZE;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400131 call_with_stack(bL_do_switch, (void *)_arg, stack);
132 BUG();
133}
134
135/*
136 * Generic switcher interface
137 */
138
Nicolas Pitreed967622012-07-05 21:33:26 -0400139static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS];
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400140static int bL_switcher_cpu_pairing[NR_CPUS];
Nicolas Pitreed967622012-07-05 21:33:26 -0400141
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400142/*
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 */
149static int bL_switch_to(unsigned int new_cluster_id)
150{
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400151 unsigned int mpidr, this_cpu, that_cpu;
152 unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster;
Nicolas Pitre6137eba2013-06-13 23:51:18 -0400153 struct completion inbound_alive;
Lorenzo Pieralisi3f09d472012-05-16 15:55:54 +0100154 struct tick_device *tdev;
155 enum clock_event_mode tdev_mode;
Nicolas Pitre108a9642012-10-23 01:39:08 -0400156 long volatile *handshake_ptr;
Nicolas Pitre6137eba2013-06-13 23:51:18 -0400157 int ipi_nr, ret;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400158
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400159 this_cpu = smp_processor_id();
160 ob_mpidr = read_mpidr();
161 ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0);
162 ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1);
163 BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400164
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400165 if (new_cluster_id == ob_cluster)
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400166 return 0;
167
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400168 that_cpu = bL_switcher_cpu_pairing[this_cpu];
169 ib_mpidr = cpu_logical_map(that_cpu);
170 ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0);
171 ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1);
172
173 pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n",
174 this_cpu, ob_mpidr, ib_mpidr);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400175
Nicolas Pitre6137eba2013-06-13 23:51:18 -0400176 this_cpu = smp_processor_id();
177
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400178 /* Close the gate for our entry vectors */
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400179 mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL);
180 mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400181
Nicolas Pitre6137eba2013-06-13 23:51:18 -0400182 /* Install our "inbound alive" notifier. */
183 init_completion(&inbound_alive);
184 ipi_nr = register_ipi_completion(&inbound_alive, this_cpu);
185 ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]);
186 mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr);
187
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400188 /*
189 * Let's wake up the inbound CPU now in case it requires some delay
190 * to come online, but leave it gated in our entry vector code.
191 */
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400192 ret = mcpm_cpu_power_up(ib_cpu, ib_cluster);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400193 if (ret) {
194 pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret);
195 return ret;
196 }
197
198 /*
Nicolas Pitre6137eba2013-06-13 23:51:18 -0400199 * Raise a SGI on the inbound CPU to make sure it doesn't stall
200 * in a possible WFI, such as in bL_power_down().
201 */
202 gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0);
203
204 /*
205 * Wait for the inbound to come up. This allows for other
206 * tasks to be scheduled in the mean time.
207 */
208 wait_for_completion(&inbound_alive);
209 mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0);
210
211 /*
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400212 * From this point we are entering the switch critical zone
213 * and can't take any interrupts anymore.
214 */
215 local_irq_disable();
216 local_fiq_disable();
Thomas Gleixner41fa4212014-07-16 21:04:50 +0000217 trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400218
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400219 /* redirect GIC's SGIs to our counterpart */
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400220 gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400221
Lorenzo Pieralisi3f09d472012-05-16 15:55:54 +0100222 tdev = tick_get_device(this_cpu);
223 if (tdev && !cpumask_equal(tdev->evtdev->cpumask, cpumask_of(this_cpu)))
224 tdev = NULL;
225 if (tdev) {
226 tdev_mode = tdev->evtdev->mode;
227 clockevents_set_mode(tdev->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
228 }
229
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400230 ret = cpu_pm_enter();
231
232 /* we can not tolerate errors at this point */
233 if (ret)
234 panic("%s: cpu_pm_enter() returned %d\n", __func__, ret);
235
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400236 /* Swap the physical CPUs in the logical map for this logical CPU. */
237 cpu_logical_map(this_cpu) = ib_mpidr;
238 cpu_logical_map(that_cpu) = ob_mpidr;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400239
240 /* Let's do the actual CPU switch. */
Nicolas Pitre108a9642012-10-23 01:39:08 -0400241 ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400242 if (ret > 0)
243 panic("%s: cpu_suspend() returned %d\n", __func__, ret);
244
245 /* We are executing on the inbound CPU at this point */
246 mpidr = read_mpidr();
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400247 pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr);
248 BUG_ON(mpidr != ib_mpidr);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400249
250 mcpm_cpu_powered_up();
251
252 ret = cpu_pm_exit();
253
Lorenzo Pieralisi3f09d472012-05-16 15:55:54 +0100254 if (tdev) {
255 clockevents_set_mode(tdev->evtdev, tdev_mode);
256 clockevents_program_event(tdev->evtdev,
257 tdev->evtdev->next_event, 1);
258 }
259
Thomas Gleixner41fa4212014-07-16 21:04:50 +0000260 trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr);
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400261 local_fiq_enable();
262 local_irq_enable();
263
Nicolas Pitre108a9642012-10-23 01:39:08 -0400264 *handshake_ptr = 1;
265 dsb_sev();
266
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400267 if (ret)
268 pr_err("%s exiting with error %d\n", __func__, ret);
269 return ret;
270}
271
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400272struct bL_thread {
Dave Martin0577fee2013-05-22 19:08:16 +0100273 spinlock_t lock;
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400274 struct task_struct *task;
275 wait_queue_head_t wq;
276 int wanted_cluster;
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500277 struct completion started;
Dave Martin0577fee2013-05-22 19:08:16 +0100278 bL_switch_completion_handler completer;
279 void *completer_cookie;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400280};
281
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400282static struct bL_thread bL_threads[NR_CPUS];
283
284static int bL_switcher_thread(void *arg)
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400285{
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400286 struct bL_thread *t = arg;
287 struct sched_param param = { .sched_priority = 1 };
288 int cluster;
Dave Martin0577fee2013-05-22 19:08:16 +0100289 bL_switch_completion_handler completer;
290 void *completer_cookie;
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400291
292 sched_setscheduler_nocheck(current, SCHED_FIFO, &param);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500293 complete(&t->started);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400294
295 do {
296 if (signal_pending(current))
297 flush_signals(current);
298 wait_event_interruptible(t->wq,
299 t->wanted_cluster != -1 ||
300 kthread_should_stop());
Dave Martin0577fee2013-05-22 19:08:16 +0100301
302 spin_lock(&t->lock);
303 cluster = t->wanted_cluster;
304 completer = t->completer;
305 completer_cookie = t->completer_cookie;
306 t->wanted_cluster = -1;
307 t->completer = NULL;
308 spin_unlock(&t->lock);
309
310 if (cluster != -1) {
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400311 bL_switch_to(cluster);
Dave Martin0577fee2013-05-22 19:08:16 +0100312
313 if (completer)
314 completer(completer_cookie);
315 }
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400316 } while (!kthread_should_stop());
317
318 return 0;
319}
320
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500321static struct task_struct *bL_switcher_thread_create(int cpu, void *arg)
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400322{
323 struct task_struct *task;
324
325 task = kthread_create_on_node(bL_switcher_thread, arg,
326 cpu_to_node(cpu), "kswitcher_%d", cpu);
327 if (!IS_ERR(task)) {
328 kthread_bind(task, cpu);
329 wake_up_process(task);
330 } else
331 pr_err("%s failed for CPU %d\n", __func__, cpu);
332 return task;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400333}
334
335/*
Dave Martin0577fee2013-05-22 19:08:16 +0100336 * bL_switch_request_cb - Switch to a specific cluster for the given CPU,
337 * with completion notification via a callback
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400338 *
339 * @cpu: the CPU to switch
340 * @new_cluster_id: the ID of the cluster to switch to.
Dave Martin0577fee2013-05-22 19:08:16 +0100341 * @completer: switch completion callback. if non-NULL,
342 * @completer(@completer_cookie) will be called on completion of
343 * the switch, in non-atomic context.
344 * @completer_cookie: opaque context argument for @completer.
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400345 *
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400346 * This function causes a cluster switch on the given CPU by waking up
347 * the appropriate switcher thread. This function may or may not return
348 * before the switch has occurred.
Dave Martin0577fee2013-05-22 19:08:16 +0100349 *
350 * If a @completer callback function is supplied, it will be called when
351 * the switch is complete. This can be used to determine asynchronously
352 * when the switch is complete, regardless of when bL_switch_request()
353 * returns. When @completer is supplied, no new switch request is permitted
354 * for the affected CPU until after the switch is complete, and @completer
355 * has returned.
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400356 */
Dave Martin0577fee2013-05-22 19:08:16 +0100357int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id,
358 bL_switch_completion_handler completer,
359 void *completer_cookie)
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400360{
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400361 struct bL_thread *t;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400362
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400363 if (cpu >= ARRAY_SIZE(bL_threads)) {
364 pr_err("%s: cpu %d out of bounds\n", __func__, cpu);
365 return -EINVAL;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400366 }
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400367
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400368 t = &bL_threads[cpu];
Dave Martin0577fee2013-05-22 19:08:16 +0100369
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400370 if (IS_ERR(t->task))
371 return PTR_ERR(t->task);
372 if (!t->task)
373 return -ESRCH;
374
Dave Martin0577fee2013-05-22 19:08:16 +0100375 spin_lock(&t->lock);
376 if (t->completer) {
377 spin_unlock(&t->lock);
378 return -EBUSY;
379 }
380 t->completer = completer;
381 t->completer_cookie = completer_cookie;
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400382 t->wanted_cluster = new_cluster_id;
Dave Martin0577fee2013-05-22 19:08:16 +0100383 spin_unlock(&t->lock);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400384 wake_up(&t->wq);
385 return 0;
Nicolas Pitre1c33be52012-04-12 02:56:10 -0400386}
Dave Martin0577fee2013-05-22 19:08:16 +0100387EXPORT_SYMBOL_GPL(bL_switch_request_cb);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400388
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500389/*
390 * Activation and configuration code.
391 */
392
Dave Martinc0f43752012-12-10 17:19:57 +0000393static DEFINE_MUTEX(bL_switcher_activation_lock);
Dave Martin491990e2012-12-10 17:19:58 +0000394static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500395static unsigned int bL_switcher_active;
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400396static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS];
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500397static cpumask_t bL_switcher_removed_logical_cpus;
398
Dave Martin491990e2012-12-10 17:19:58 +0000399int bL_switcher_register_notifier(struct notifier_block *nb)
400{
401 return blocking_notifier_chain_register(&bL_activation_notifier, nb);
402}
403EXPORT_SYMBOL_GPL(bL_switcher_register_notifier);
404
405int bL_switcher_unregister_notifier(struct notifier_block *nb)
406{
407 return blocking_notifier_chain_unregister(&bL_activation_notifier, nb);
408}
409EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier);
410
411static int bL_activation_notify(unsigned long val)
412{
413 int ret;
414
415 ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL);
416 if (ret & NOTIFY_STOP_MASK)
417 pr_err("%s: notifier chain failed with status 0x%x\n",
418 __func__, ret);
419 return notifier_to_errno(ret);
420}
421
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500422static void bL_switcher_restore_cpus(void)
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500423{
424 int i;
425
Nicolas Pitre3f8517e2014-05-23 22:31:44 +0100426 for_each_cpu(i, &bL_switcher_removed_logical_cpus) {
427 struct device *cpu_dev = get_cpu_device(i);
428 int ret = device_online(cpu_dev);
429 if (ret)
430 dev_err(cpu_dev, "switcher: unable to restore CPU\n");
431 }
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500432}
433
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500434static int bL_switcher_halve_cpus(void)
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500435{
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400436 int i, j, cluster_0, gic_id, ret;
437 unsigned int cpu, cluster, mask;
438 cpumask_t available_cpus;
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500439
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400440 /* First pass to validate what we have */
441 mask = 0;
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500442 for_each_online_cpu(i) {
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400443 cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);
444 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500445 if (cluster >= 2) {
446 pr_err("%s: only dual cluster systems are supported\n", __func__);
447 return -EINVAL;
448 }
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400449 if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER))
450 return -EINVAL;
451 mask |= (1 << cluster);
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500452 }
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400453 if (mask != 3) {
454 pr_err("%s: no CPU pairing possible\n", __func__);
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500455 return -EINVAL;
456 }
457
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400458 /*
459 * Now let's do the pairing. We match each CPU with another CPU
460 * from a different cluster. To get a uniform scheduling behavior
461 * without fiddling with CPU topology and compute capacity data,
462 * we'll use logical CPUs initially belonging to the same cluster.
463 */
464 memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing));
465 cpumask_copy(&available_cpus, cpu_online_mask);
466 cluster_0 = -1;
467 for_each_cpu(i, &available_cpus) {
468 int match = -1;
469 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
470 if (cluster_0 == -1)
471 cluster_0 = cluster;
472 if (cluster != cluster_0)
473 continue;
474 cpumask_clear_cpu(i, &available_cpus);
475 for_each_cpu(j, &available_cpus) {
476 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1);
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500477 /*
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400478 * Let's remember the last match to create "odd"
479 * pairings on purpose in order for other code not
480 * to assume any relation between physical and
481 * logical CPU numbers.
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500482 */
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400483 if (cluster != cluster_0)
484 match = j;
485 }
486 if (match != -1) {
487 bL_switcher_cpu_pairing[i] = match;
488 cpumask_clear_cpu(match, &available_cpus);
489 pr_info("CPU%d paired with CPU%d\n", i, match);
490 }
491 }
492
493 /*
494 * Now we disable the unwanted CPUs i.e. everything that has no
495 * pairing information (that includes the pairing counterparts).
496 */
497 cpumask_clear(&bL_switcher_removed_logical_cpus);
498 for_each_online_cpu(i) {
499 cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0);
500 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1);
501
502 /* Let's take note of the GIC ID for this CPU */
503 gic_id = gic_get_cpu_id(i);
504 if (gic_id < 0) {
505 pr_err("%s: bad GIC ID for CPU %d\n", __func__, i);
506 bL_switcher_restore_cpus();
507 return -EINVAL;
508 }
509 bL_gic_id[cpu][cluster] = gic_id;
510 pr_info("GIC ID for CPU %u cluster %u is %u\n",
511 cpu, cluster, gic_id);
512
513 if (bL_switcher_cpu_pairing[i] != -1) {
514 bL_switcher_cpu_original_cluster[i] = cluster;
515 continue;
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500516 }
517
Nicolas Pitre3f8517e2014-05-23 22:31:44 +0100518 ret = device_offline(get_cpu_device(i));
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500519 if (ret) {
520 bL_switcher_restore_cpus();
521 return ret;
522 }
523 cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus);
524 }
525
526 return 0;
527}
528
Dave Martind08e2e02013-02-13 16:20:44 +0000529/* Determine the logical CPU a given physical CPU is grouped on. */
530int bL_switcher_get_logical_index(u32 mpidr)
531{
532 int cpu;
533
534 if (!bL_switcher_active)
535 return -EUNATCH;
536
537 mpidr &= MPIDR_HWID_BITMASK;
538 for_each_online_cpu(cpu) {
539 int pairing = bL_switcher_cpu_pairing[cpu];
540 if (pairing == -1)
541 continue;
542 if ((mpidr == cpu_logical_map(cpu)) ||
543 (mpidr == cpu_logical_map(pairing)))
544 return cpu;
545 }
546 return -EINVAL;
547}
548
Dave Martinb09bbe52013-02-06 15:45:23 +0000549static void bL_switcher_trace_trigger_cpu(void *__always_unused info)
550{
Thomas Gleixner41fa4212014-07-16 21:04:50 +0000551 trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr());
Dave Martinb09bbe52013-02-06 15:45:23 +0000552}
553
Dave Martin29064b82013-02-11 14:39:19 +0000554int bL_switcher_trace_trigger(void)
Dave Martinb09bbe52013-02-06 15:45:23 +0000555{
556 int ret;
557
558 preempt_disable();
559
560 bL_switcher_trace_trigger_cpu(NULL);
561 ret = smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true);
562
563 preempt_enable();
564
565 return ret;
566}
Dave Martin29064b82013-02-11 14:39:19 +0000567EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger);
Dave Martinb09bbe52013-02-06 15:45:23 +0000568
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500569static int bL_switcher_enable(void)
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400570{
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500571 int cpu, ret;
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400572
Dave Martinc0f43752012-12-10 17:19:57 +0000573 mutex_lock(&bL_switcher_activation_lock);
Tushar Beherab0ced9d22013-10-31 06:46:14 +0100574 lock_device_hotplug();
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500575 if (bL_switcher_active) {
Tushar Beherab0ced9d22013-10-31 06:46:14 +0100576 unlock_device_hotplug();
Dave Martinc0f43752012-12-10 17:19:57 +0000577 mutex_unlock(&bL_switcher_activation_lock);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500578 return 0;
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500579 }
580
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500581 pr_info("big.LITTLE switcher initializing\n");
582
Dave Martin491990e2012-12-10 17:19:58 +0000583 ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE);
584 if (ret)
585 goto error;
586
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500587 ret = bL_switcher_halve_cpus();
Dave Martin491990e2012-12-10 17:19:58 +0000588 if (ret)
589 goto error;
Nicolas Pitre9797a0e2012-11-21 11:53:27 -0500590
Dave Martinb09bbe52013-02-06 15:45:23 +0000591 bL_switcher_trace_trigger();
592
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400593 for_each_online_cpu(cpu) {
594 struct bL_thread *t = &bL_threads[cpu];
Dave Martin0577fee2013-05-22 19:08:16 +0100595 spin_lock_init(&t->lock);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400596 init_waitqueue_head(&t->wq);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500597 init_completion(&t->started);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400598 t->wanted_cluster = -1;
599 t->task = bL_switcher_thread_create(cpu, t);
600 }
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500601
602 bL_switcher_active = 1;
Dave Martin491990e2012-12-10 17:19:58 +0000603 bL_activation_notify(BL_NOTIFY_POST_ENABLE);
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400604 pr_info("big.LITTLE switcher initialized\n");
Dave Martin491990e2012-12-10 17:19:58 +0000605 goto out;
Dave Martinc0f43752012-12-10 17:19:57 +0000606
Dave Martin491990e2012-12-10 17:19:58 +0000607error:
608 pr_warn("big.LITTLE switcher initialization failed\n");
609 bL_activation_notify(BL_NOTIFY_POST_DISABLE);
610
611out:
Tushar Beherab0ced9d22013-10-31 06:46:14 +0100612 unlock_device_hotplug();
Dave Martinc0f43752012-12-10 17:19:57 +0000613 mutex_unlock(&bL_switcher_activation_lock);
Dave Martin491990e2012-12-10 17:19:58 +0000614 return ret;
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400615}
616
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500617#ifdef CONFIG_SYSFS
618
619static void bL_switcher_disable(void)
620{
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400621 unsigned int cpu, cluster;
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500622 struct bL_thread *t;
623 struct task_struct *task;
624
Dave Martinc0f43752012-12-10 17:19:57 +0000625 mutex_lock(&bL_switcher_activation_lock);
Tushar Beherab0ced9d22013-10-31 06:46:14 +0100626 lock_device_hotplug();
Dave Martin491990e2012-12-10 17:19:58 +0000627
628 if (!bL_switcher_active)
629 goto out;
630
631 if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) {
632 bL_activation_notify(BL_NOTIFY_POST_ENABLE);
633 goto out;
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500634 }
Dave Martin491990e2012-12-10 17:19:58 +0000635
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500636 bL_switcher_active = 0;
637
638 /*
639 * To deactivate the switcher, we must shut down the switcher
640 * threads to prevent any other requests from being accepted.
641 * Then, if the final cluster for given logical CPU is not the
642 * same as the original one, we'll recreate a switcher thread
643 * just for the purpose of switching the CPU back without any
644 * possibility for interference from external requests.
645 */
646 for_each_online_cpu(cpu) {
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500647 t = &bL_threads[cpu];
648 task = t->task;
649 t->task = NULL;
650 if (!task || IS_ERR(task))
651 continue;
652 kthread_stop(task);
653 /* no more switch may happen on this CPU at this point */
654 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
655 if (cluster == bL_switcher_cpu_original_cluster[cpu])
656 continue;
657 init_completion(&t->started);
658 t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu];
659 task = bL_switcher_thread_create(cpu, t);
660 if (!IS_ERR(task)) {
661 wait_for_completion(&t->started);
662 kthread_stop(task);
663 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
664 if (cluster == bL_switcher_cpu_original_cluster[cpu])
665 continue;
666 }
667 /* If execution gets here, we're in trouble. */
668 pr_crit("%s: unable to restore original cluster for CPU %d\n",
669 __func__, cpu);
Nicolas Pitre38c35d42013-06-13 23:42:46 -0400670 pr_crit("%s: CPU %d can't be restored\n",
671 __func__, bL_switcher_cpu_pairing[cpu]);
672 cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu],
673 &bL_switcher_removed_logical_cpus);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500674 }
675
676 bL_switcher_restore_cpus();
Dave Martinb09bbe52013-02-06 15:45:23 +0000677 bL_switcher_trace_trigger();
678
Dave Martin491990e2012-12-10 17:19:58 +0000679 bL_activation_notify(BL_NOTIFY_POST_DISABLE);
680
681out:
Tushar Beherab0ced9d22013-10-31 06:46:14 +0100682 unlock_device_hotplug();
Dave Martinc0f43752012-12-10 17:19:57 +0000683 mutex_unlock(&bL_switcher_activation_lock);
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500684}
685
686static ssize_t bL_switcher_active_show(struct kobject *kobj,
687 struct kobj_attribute *attr, char *buf)
688{
689 return sprintf(buf, "%u\n", bL_switcher_active);
690}
691
692static ssize_t bL_switcher_active_store(struct kobject *kobj,
693 struct kobj_attribute *attr, const char *buf, size_t count)
694{
695 int ret;
696
697 switch (buf[0]) {
698 case '0':
699 bL_switcher_disable();
700 ret = 0;
701 break;
702 case '1':
703 ret = bL_switcher_enable();
704 break;
705 default:
706 ret = -EINVAL;
707 }
708
709 return (ret >= 0) ? count : ret;
710}
711
Dave Martinb09bbe52013-02-06 15:45:23 +0000712static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj,
713 struct kobj_attribute *attr, const char *buf, size_t count)
714{
715 int ret = bL_switcher_trace_trigger();
716
717 return ret ? ret : count;
718}
719
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500720static struct kobj_attribute bL_switcher_active_attr =
721 __ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store);
722
Dave Martinb09bbe52013-02-06 15:45:23 +0000723static struct kobj_attribute bL_switcher_trace_trigger_attr =
724 __ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store);
725
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500726static struct attribute *bL_switcher_attrs[] = {
727 &bL_switcher_active_attr.attr,
Dave Martinb09bbe52013-02-06 15:45:23 +0000728 &bL_switcher_trace_trigger_attr.attr,
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500729 NULL,
730};
731
732static struct attribute_group bL_switcher_attr_group = {
733 .attrs = bL_switcher_attrs,
734};
735
736static struct kobject *bL_switcher_kobj;
737
738static int __init bL_switcher_sysfs_init(void)
739{
740 int ret;
741
742 bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj);
743 if (!bL_switcher_kobj)
744 return -ENOMEM;
745 ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group);
746 if (ret)
747 kobject_put(bL_switcher_kobj);
748 return ret;
749}
750
751#endif /* CONFIG_SYSFS */
752
Dave Martinc0f43752012-12-10 17:19:57 +0000753bool bL_switcher_get_enabled(void)
754{
755 mutex_lock(&bL_switcher_activation_lock);
756
757 return bL_switcher_active;
758}
759EXPORT_SYMBOL_GPL(bL_switcher_get_enabled);
760
761void bL_switcher_put_enabled(void)
762{
763 mutex_unlock(&bL_switcher_activation_lock);
764}
765EXPORT_SYMBOL_GPL(bL_switcher_put_enabled);
766
Nicolas Pitre272614352012-11-26 22:48:55 -0500767/*
768 * Veto any CPU hotplug operation on those CPUs we've removed
769 * while the switcher is active.
770 * We're just not ready to deal with that given the trickery involved.
771 */
772static int bL_switcher_hotplug_callback(struct notifier_block *nfb,
773 unsigned long action, void *hcpu)
774{
775 if (bL_switcher_active) {
776 int pairing = bL_switcher_cpu_pairing[(unsigned long)hcpu];
777 switch (action & 0xf) {
778 case CPU_UP_PREPARE:
779 case CPU_DOWN_PREPARE:
780 if (pairing == -1)
781 return NOTIFY_BAD;
782 }
783 }
784 return NOTIFY_DONE;
785}
786
Nicolas Pitrec4821c02012-11-22 13:33:35 -0500787static bool no_bL_switcher;
788core_param(no_bL_switcher, no_bL_switcher, bool, 0644);
789
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500790static int __init bL_switcher_init(void)
791{
792 int ret;
793
Nicolas Pitre4530e4b2014-04-22 00:25:35 +0100794 if (!mcpm_is_available())
795 return -ENODEV;
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500796
Nicolas Pitre272614352012-11-26 22:48:55 -0500797 cpu_notifier(bL_switcher_hotplug_callback, 0);
798
Nicolas Pitrec4821c02012-11-22 13:33:35 -0500799 if (!no_bL_switcher) {
800 ret = bL_switcher_enable();
801 if (ret)
802 return ret;
803 }
Nicolas Pitre6b7437a2012-11-22 00:05:07 -0500804
805#ifdef CONFIG_SYSFS
806 ret = bL_switcher_sysfs_init();
807 if (ret)
808 pr_err("%s: unable to create sysfs entry\n", __func__);
809#endif
810
811 return 0;
812}
813
Nicolas Pitre71ce1de2012-10-26 02:36:17 -0400814late_initcall(bL_switcher_init);