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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 | ||
12 | #include <linux/init.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/interrupt.h> | |
17 | #include <linux/cpu_pm.h> | |
71ce1dee | 18 | #include <linux/cpu.h> |
3f09d479 | 19 | #include <linux/cpumask.h> |
71ce1dee NP |
20 | #include <linux/kthread.h> |
21 | #include <linux/wait.h> | |
3f09d479 LP |
22 | #include <linux/clockchips.h> |
23 | #include <linux/hrtimer.h> | |
24 | #include <linux/tick.h> | |
1c33be57 NP |
25 | #include <linux/mm.h> |
26 | #include <linux/string.h> | |
6b7437ae | 27 | #include <linux/sysfs.h> |
1c33be57 | 28 | #include <linux/irqchip/arm-gic.h> |
c4821c05 | 29 | #include <linux/moduleparam.h> |
1c33be57 NP |
30 | |
31 | #include <asm/smp_plat.h> | |
32 | #include <asm/suspend.h> | |
33 | #include <asm/mcpm.h> | |
34 | #include <asm/bL_switcher.h> | |
35 | ||
36 | ||
37 | /* | |
38 | * Use our own MPIDR accessors as the generic ones in asm/cputype.h have | |
39 | * __attribute_const__ and we don't want the compiler to assume any | |
40 | * constness here as the value _does_ change along some code paths. | |
41 | */ | |
42 | ||
43 | static int read_mpidr(void) | |
44 | { | |
45 | unsigned int id; | |
46 | asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id)); | |
47 | return id & MPIDR_HWID_BITMASK; | |
48 | } | |
49 | ||
50 | /* | |
51 | * bL switcher core code. | |
52 | */ | |
53 | ||
54 | static void bL_do_switch(void *_unused) | |
55 | { | |
38c35d4f | 56 | unsigned ib_mpidr, ib_cpu, ib_cluster; |
1c33be57 | 57 | |
1c33be57 NP |
58 | pr_debug("%s\n", __func__); |
59 | ||
38c35d4f NP |
60 | ib_mpidr = cpu_logical_map(smp_processor_id()); |
61 | ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); | |
62 | ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); | |
1c33be57 NP |
63 | |
64 | /* | |
65 | * Our state has been saved at this point. Let's release our | |
66 | * inbound CPU. | |
67 | */ | |
38c35d4f | 68 | mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume); |
1c33be57 NP |
69 | sev(); |
70 | ||
71 | /* | |
72 | * From this point, we must assume that our counterpart CPU might | |
73 | * have taken over in its parallel world already, as if execution | |
74 | * just returned from cpu_suspend(). It is therefore important to | |
75 | * be very careful not to make any change the other guy is not | |
76 | * expecting. This is why we need stack isolation. | |
77 | * | |
78 | * Fancy under cover tasks could be performed here. For now | |
79 | * we have none. | |
80 | */ | |
81 | ||
82 | /* Let's put ourself down. */ | |
83 | mcpm_cpu_power_down(); | |
84 | ||
85 | /* should never get here */ | |
86 | BUG(); | |
87 | } | |
88 | ||
89 | /* | |
c052de26 NP |
90 | * Stack isolation. To ensure 'current' remains valid, we just use another |
91 | * piece of our thread's stack space which should be fairly lightly used. | |
92 | * The selected area starts just above the thread_info structure located | |
93 | * at the very bottom of the stack, aligned to a cache line, and indexed | |
94 | * with the cluster number. | |
1c33be57 | 95 | */ |
c052de26 | 96 | #define STACK_SIZE 512 |
1c33be57 NP |
97 | extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); |
98 | static int bL_switchpoint(unsigned long _arg) | |
99 | { | |
100 | unsigned int mpidr = read_mpidr(); | |
1c33be57 | 101 | unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1); |
c052de26 | 102 | void *stack = current_thread_info() + 1; |
1c33be57 | 103 | stack = PTR_ALIGN(stack, L1_CACHE_BYTES); |
c052de26 | 104 | stack += clusterid * STACK_SIZE + STACK_SIZE; |
1c33be57 NP |
105 | call_with_stack(bL_do_switch, (void *)_arg, stack); |
106 | BUG(); | |
107 | } | |
108 | ||
109 | /* | |
110 | * Generic switcher interface | |
111 | */ | |
112 | ||
ed96762e | 113 | static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS]; |
38c35d4f | 114 | static int bL_switcher_cpu_pairing[NR_CPUS]; |
ed96762e | 115 | |
1c33be57 NP |
116 | /* |
117 | * bL_switch_to - Switch to a specific cluster for the current CPU | |
118 | * @new_cluster_id: the ID of the cluster to switch to. | |
119 | * | |
120 | * This function must be called on the CPU to be switched. | |
121 | * Returns 0 on success, else a negative status code. | |
122 | */ | |
123 | static int bL_switch_to(unsigned int new_cluster_id) | |
124 | { | |
38c35d4f NP |
125 | unsigned int mpidr, this_cpu, that_cpu; |
126 | unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; | |
3f09d479 LP |
127 | struct tick_device *tdev; |
128 | enum clock_event_mode tdev_mode; | |
1c33be57 NP |
129 | int ret; |
130 | ||
38c35d4f NP |
131 | this_cpu = smp_processor_id(); |
132 | ob_mpidr = read_mpidr(); | |
133 | ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0); | |
134 | ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1); | |
135 | BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr); | |
1c33be57 | 136 | |
38c35d4f | 137 | if (new_cluster_id == ob_cluster) |
1c33be57 NP |
138 | return 0; |
139 | ||
38c35d4f NP |
140 | that_cpu = bL_switcher_cpu_pairing[this_cpu]; |
141 | ib_mpidr = cpu_logical_map(that_cpu); | |
142 | ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); | |
143 | ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); | |
144 | ||
145 | pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n", | |
146 | this_cpu, ob_mpidr, ib_mpidr); | |
1c33be57 NP |
147 | |
148 | /* Close the gate for our entry vectors */ | |
38c35d4f NP |
149 | mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL); |
150 | mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL); | |
1c33be57 NP |
151 | |
152 | /* | |
153 | * Let's wake up the inbound CPU now in case it requires some delay | |
154 | * to come online, but leave it gated in our entry vector code. | |
155 | */ | |
38c35d4f | 156 | ret = mcpm_cpu_power_up(ib_cpu, ib_cluster); |
1c33be57 NP |
157 | if (ret) { |
158 | pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret); | |
159 | return ret; | |
160 | } | |
161 | ||
162 | /* | |
163 | * From this point we are entering the switch critical zone | |
164 | * and can't take any interrupts anymore. | |
165 | */ | |
166 | local_irq_disable(); | |
167 | local_fiq_disable(); | |
168 | ||
1c33be57 | 169 | /* redirect GIC's SGIs to our counterpart */ |
38c35d4f | 170 | gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]); |
1c33be57 NP |
171 | |
172 | /* | |
173 | * Raise a SGI on the inbound CPU to make sure it doesn't stall | |
174 | * in a possible WFI, such as in mcpm_power_down(). | |
175 | */ | |
176 | arch_send_wakeup_ipi_mask(cpumask_of(this_cpu)); | |
177 | ||
3f09d479 LP |
178 | tdev = tick_get_device(this_cpu); |
179 | if (tdev && !cpumask_equal(tdev->evtdev->cpumask, cpumask_of(this_cpu))) | |
180 | tdev = NULL; | |
181 | if (tdev) { | |
182 | tdev_mode = tdev->evtdev->mode; | |
183 | clockevents_set_mode(tdev->evtdev, CLOCK_EVT_MODE_SHUTDOWN); | |
184 | } | |
185 | ||
1c33be57 NP |
186 | ret = cpu_pm_enter(); |
187 | ||
188 | /* we can not tolerate errors at this point */ | |
189 | if (ret) | |
190 | panic("%s: cpu_pm_enter() returned %d\n", __func__, ret); | |
191 | ||
38c35d4f NP |
192 | /* Swap the physical CPUs in the logical map for this logical CPU. */ |
193 | cpu_logical_map(this_cpu) = ib_mpidr; | |
194 | cpu_logical_map(that_cpu) = ob_mpidr; | |
1c33be57 NP |
195 | |
196 | /* Let's do the actual CPU switch. */ | |
197 | ret = cpu_suspend(0, bL_switchpoint); | |
198 | if (ret > 0) | |
199 | panic("%s: cpu_suspend() returned %d\n", __func__, ret); | |
200 | ||
201 | /* We are executing on the inbound CPU at this point */ | |
202 | mpidr = read_mpidr(); | |
38c35d4f NP |
203 | pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr); |
204 | BUG_ON(mpidr != ib_mpidr); | |
1c33be57 NP |
205 | |
206 | mcpm_cpu_powered_up(); | |
207 | ||
208 | ret = cpu_pm_exit(); | |
209 | ||
3f09d479 LP |
210 | if (tdev) { |
211 | clockevents_set_mode(tdev->evtdev, tdev_mode); | |
212 | clockevents_program_event(tdev->evtdev, | |
213 | tdev->evtdev->next_event, 1); | |
214 | } | |
215 | ||
1c33be57 NP |
216 | local_fiq_enable(); |
217 | local_irq_enable(); | |
218 | ||
219 | if (ret) | |
220 | pr_err("%s exiting with error %d\n", __func__, ret); | |
221 | return ret; | |
222 | } | |
223 | ||
71ce1dee NP |
224 | struct bL_thread { |
225 | struct task_struct *task; | |
226 | wait_queue_head_t wq; | |
227 | int wanted_cluster; | |
6b7437ae | 228 | struct completion started; |
1c33be57 NP |
229 | }; |
230 | ||
71ce1dee NP |
231 | static struct bL_thread bL_threads[NR_CPUS]; |
232 | ||
233 | static int bL_switcher_thread(void *arg) | |
234 | { | |
235 | struct bL_thread *t = arg; | |
236 | struct sched_param param = { .sched_priority = 1 }; | |
237 | int cluster; | |
238 | ||
239 | sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); | |
6b7437ae | 240 | complete(&t->started); |
71ce1dee NP |
241 | |
242 | do { | |
243 | if (signal_pending(current)) | |
244 | flush_signals(current); | |
245 | wait_event_interruptible(t->wq, | |
246 | t->wanted_cluster != -1 || | |
247 | kthread_should_stop()); | |
248 | cluster = xchg(&t->wanted_cluster, -1); | |
249 | if (cluster != -1) | |
250 | bL_switch_to(cluster); | |
251 | } while (!kthread_should_stop()); | |
252 | ||
253 | return 0; | |
254 | } | |
255 | ||
6b7437ae | 256 | static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) |
1c33be57 | 257 | { |
71ce1dee NP |
258 | struct task_struct *task; |
259 | ||
260 | task = kthread_create_on_node(bL_switcher_thread, arg, | |
261 | cpu_to_node(cpu), "kswitcher_%d", cpu); | |
262 | if (!IS_ERR(task)) { | |
263 | kthread_bind(task, cpu); | |
264 | wake_up_process(task); | |
265 | } else | |
266 | pr_err("%s failed for CPU %d\n", __func__, cpu); | |
267 | return task; | |
1c33be57 NP |
268 | } |
269 | ||
270 | /* | |
271 | * bL_switch_request - Switch to a specific cluster for the given CPU | |
272 | * | |
273 | * @cpu: the CPU to switch | |
274 | * @new_cluster_id: the ID of the cluster to switch to. | |
275 | * | |
71ce1dee NP |
276 | * This function causes a cluster switch on the given CPU by waking up |
277 | * the appropriate switcher thread. This function may or may not return | |
278 | * before the switch has occurred. | |
1c33be57 | 279 | */ |
71ce1dee | 280 | int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id) |
1c33be57 | 281 | { |
71ce1dee | 282 | struct bL_thread *t; |
1c33be57 | 283 | |
71ce1dee NP |
284 | if (cpu >= ARRAY_SIZE(bL_threads)) { |
285 | pr_err("%s: cpu %d out of bounds\n", __func__, cpu); | |
286 | return -EINVAL; | |
1c33be57 | 287 | } |
1c33be57 | 288 | |
71ce1dee NP |
289 | t = &bL_threads[cpu]; |
290 | if (IS_ERR(t->task)) | |
291 | return PTR_ERR(t->task); | |
292 | if (!t->task) | |
293 | return -ESRCH; | |
294 | ||
295 | t->wanted_cluster = new_cluster_id; | |
296 | wake_up(&t->wq); | |
297 | return 0; | |
1c33be57 NP |
298 | } |
299 | EXPORT_SYMBOL_GPL(bL_switch_request); | |
71ce1dee | 300 | |
9797a0e9 NP |
301 | /* |
302 | * Activation and configuration code. | |
303 | */ | |
304 | ||
6b7437ae | 305 | static unsigned int bL_switcher_active; |
38c35d4f | 306 | static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS]; |
9797a0e9 NP |
307 | static cpumask_t bL_switcher_removed_logical_cpus; |
308 | ||
6b7437ae | 309 | static void bL_switcher_restore_cpus(void) |
9797a0e9 NP |
310 | { |
311 | int i; | |
312 | ||
313 | for_each_cpu(i, &bL_switcher_removed_logical_cpus) | |
314 | cpu_up(i); | |
315 | } | |
316 | ||
6b7437ae | 317 | static int bL_switcher_halve_cpus(void) |
9797a0e9 | 318 | { |
38c35d4f NP |
319 | int i, j, cluster_0, gic_id, ret; |
320 | unsigned int cpu, cluster, mask; | |
321 | cpumask_t available_cpus; | |
9797a0e9 | 322 | |
38c35d4f NP |
323 | /* First pass to validate what we have */ |
324 | mask = 0; | |
9797a0e9 | 325 | for_each_online_cpu(i) { |
38c35d4f NP |
326 | cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); |
327 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
9797a0e9 NP |
328 | if (cluster >= 2) { |
329 | pr_err("%s: only dual cluster systems are supported\n", __func__); | |
330 | return -EINVAL; | |
331 | } | |
38c35d4f NP |
332 | if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER)) |
333 | return -EINVAL; | |
334 | mask |= (1 << cluster); | |
9797a0e9 | 335 | } |
38c35d4f NP |
336 | if (mask != 3) { |
337 | pr_err("%s: no CPU pairing possible\n", __func__); | |
9797a0e9 NP |
338 | return -EINVAL; |
339 | } | |
340 | ||
38c35d4f NP |
341 | /* |
342 | * Now let's do the pairing. We match each CPU with another CPU | |
343 | * from a different cluster. To get a uniform scheduling behavior | |
344 | * without fiddling with CPU topology and compute capacity data, | |
345 | * we'll use logical CPUs initially belonging to the same cluster. | |
346 | */ | |
347 | memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing)); | |
348 | cpumask_copy(&available_cpus, cpu_online_mask); | |
349 | cluster_0 = -1; | |
350 | for_each_cpu(i, &available_cpus) { | |
351 | int match = -1; | |
352 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
353 | if (cluster_0 == -1) | |
354 | cluster_0 = cluster; | |
355 | if (cluster != cluster_0) | |
356 | continue; | |
357 | cpumask_clear_cpu(i, &available_cpus); | |
358 | for_each_cpu(j, &available_cpus) { | |
359 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1); | |
9797a0e9 | 360 | /* |
38c35d4f NP |
361 | * Let's remember the last match to create "odd" |
362 | * pairings on purpose in order for other code not | |
363 | * to assume any relation between physical and | |
364 | * logical CPU numbers. | |
9797a0e9 | 365 | */ |
38c35d4f NP |
366 | if (cluster != cluster_0) |
367 | match = j; | |
368 | } | |
369 | if (match != -1) { | |
370 | bL_switcher_cpu_pairing[i] = match; | |
371 | cpumask_clear_cpu(match, &available_cpus); | |
372 | pr_info("CPU%d paired with CPU%d\n", i, match); | |
373 | } | |
374 | } | |
375 | ||
376 | /* | |
377 | * Now we disable the unwanted CPUs i.e. everything that has no | |
378 | * pairing information (that includes the pairing counterparts). | |
379 | */ | |
380 | cpumask_clear(&bL_switcher_removed_logical_cpus); | |
381 | for_each_online_cpu(i) { | |
382 | cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); | |
383 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); | |
384 | ||
385 | /* Let's take note of the GIC ID for this CPU */ | |
386 | gic_id = gic_get_cpu_id(i); | |
387 | if (gic_id < 0) { | |
388 | pr_err("%s: bad GIC ID for CPU %d\n", __func__, i); | |
389 | bL_switcher_restore_cpus(); | |
390 | return -EINVAL; | |
391 | } | |
392 | bL_gic_id[cpu][cluster] = gic_id; | |
393 | pr_info("GIC ID for CPU %u cluster %u is %u\n", | |
394 | cpu, cluster, gic_id); | |
395 | ||
396 | if (bL_switcher_cpu_pairing[i] != -1) { | |
397 | bL_switcher_cpu_original_cluster[i] = cluster; | |
398 | continue; | |
9797a0e9 NP |
399 | } |
400 | ||
401 | ret = cpu_down(i); | |
402 | if (ret) { | |
403 | bL_switcher_restore_cpus(); | |
404 | return ret; | |
405 | } | |
406 | cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus); | |
407 | } | |
408 | ||
409 | return 0; | |
410 | } | |
411 | ||
6b7437ae | 412 | static int bL_switcher_enable(void) |
71ce1dee | 413 | { |
9797a0e9 | 414 | int cpu, ret; |
71ce1dee | 415 | |
6b7437ae NP |
416 | cpu_hotplug_driver_lock(); |
417 | if (bL_switcher_active) { | |
418 | cpu_hotplug_driver_unlock(); | |
419 | return 0; | |
9797a0e9 NP |
420 | } |
421 | ||
6b7437ae NP |
422 | pr_info("big.LITTLE switcher initializing\n"); |
423 | ||
9797a0e9 NP |
424 | ret = bL_switcher_halve_cpus(); |
425 | if (ret) { | |
426 | cpu_hotplug_driver_unlock(); | |
427 | return ret; | |
428 | } | |
429 | ||
71ce1dee NP |
430 | for_each_online_cpu(cpu) { |
431 | struct bL_thread *t = &bL_threads[cpu]; | |
432 | init_waitqueue_head(&t->wq); | |
6b7437ae | 433 | init_completion(&t->started); |
71ce1dee NP |
434 | t->wanted_cluster = -1; |
435 | t->task = bL_switcher_thread_create(cpu, t); | |
436 | } | |
6b7437ae NP |
437 | |
438 | bL_switcher_active = 1; | |
9797a0e9 | 439 | cpu_hotplug_driver_unlock(); |
71ce1dee NP |
440 | |
441 | pr_info("big.LITTLE switcher initialized\n"); | |
442 | return 0; | |
443 | } | |
444 | ||
6b7437ae NP |
445 | #ifdef CONFIG_SYSFS |
446 | ||
447 | static void bL_switcher_disable(void) | |
448 | { | |
38c35d4f | 449 | unsigned int cpu, cluster; |
6b7437ae NP |
450 | struct bL_thread *t; |
451 | struct task_struct *task; | |
452 | ||
453 | cpu_hotplug_driver_lock(); | |
454 | if (!bL_switcher_active) { | |
455 | cpu_hotplug_driver_unlock(); | |
456 | return; | |
457 | } | |
458 | bL_switcher_active = 0; | |
459 | ||
460 | /* | |
461 | * To deactivate the switcher, we must shut down the switcher | |
462 | * threads to prevent any other requests from being accepted. | |
463 | * Then, if the final cluster for given logical CPU is not the | |
464 | * same as the original one, we'll recreate a switcher thread | |
465 | * just for the purpose of switching the CPU back without any | |
466 | * possibility for interference from external requests. | |
467 | */ | |
468 | for_each_online_cpu(cpu) { | |
6b7437ae NP |
469 | t = &bL_threads[cpu]; |
470 | task = t->task; | |
471 | t->task = NULL; | |
472 | if (!task || IS_ERR(task)) | |
473 | continue; | |
474 | kthread_stop(task); | |
475 | /* no more switch may happen on this CPU at this point */ | |
476 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); | |
477 | if (cluster == bL_switcher_cpu_original_cluster[cpu]) | |
478 | continue; | |
479 | init_completion(&t->started); | |
480 | t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu]; | |
481 | task = bL_switcher_thread_create(cpu, t); | |
482 | if (!IS_ERR(task)) { | |
483 | wait_for_completion(&t->started); | |
484 | kthread_stop(task); | |
485 | cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); | |
486 | if (cluster == bL_switcher_cpu_original_cluster[cpu]) | |
487 | continue; | |
488 | } | |
489 | /* If execution gets here, we're in trouble. */ | |
490 | pr_crit("%s: unable to restore original cluster for CPU %d\n", | |
491 | __func__, cpu); | |
38c35d4f NP |
492 | pr_crit("%s: CPU %d can't be restored\n", |
493 | __func__, bL_switcher_cpu_pairing[cpu]); | |
494 | cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu], | |
495 | &bL_switcher_removed_logical_cpus); | |
6b7437ae NP |
496 | } |
497 | ||
498 | bL_switcher_restore_cpus(); | |
499 | cpu_hotplug_driver_unlock(); | |
500 | } | |
501 | ||
502 | static ssize_t bL_switcher_active_show(struct kobject *kobj, | |
503 | struct kobj_attribute *attr, char *buf) | |
504 | { | |
505 | return sprintf(buf, "%u\n", bL_switcher_active); | |
506 | } | |
507 | ||
508 | static ssize_t bL_switcher_active_store(struct kobject *kobj, | |
509 | struct kobj_attribute *attr, const char *buf, size_t count) | |
510 | { | |
511 | int ret; | |
512 | ||
513 | switch (buf[0]) { | |
514 | case '0': | |
515 | bL_switcher_disable(); | |
516 | ret = 0; | |
517 | break; | |
518 | case '1': | |
519 | ret = bL_switcher_enable(); | |
520 | break; | |
521 | default: | |
522 | ret = -EINVAL; | |
523 | } | |
524 | ||
525 | return (ret >= 0) ? count : ret; | |
526 | } | |
527 | ||
528 | static struct kobj_attribute bL_switcher_active_attr = | |
529 | __ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store); | |
530 | ||
531 | static struct attribute *bL_switcher_attrs[] = { | |
532 | &bL_switcher_active_attr.attr, | |
533 | NULL, | |
534 | }; | |
535 | ||
536 | static struct attribute_group bL_switcher_attr_group = { | |
537 | .attrs = bL_switcher_attrs, | |
538 | }; | |
539 | ||
540 | static struct kobject *bL_switcher_kobj; | |
541 | ||
542 | static int __init bL_switcher_sysfs_init(void) | |
543 | { | |
544 | int ret; | |
545 | ||
546 | bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj); | |
547 | if (!bL_switcher_kobj) | |
548 | return -ENOMEM; | |
549 | ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group); | |
550 | if (ret) | |
551 | kobject_put(bL_switcher_kobj); | |
552 | return ret; | |
553 | } | |
554 | ||
555 | #endif /* CONFIG_SYSFS */ | |
556 | ||
c4821c05 NP |
557 | static bool no_bL_switcher; |
558 | core_param(no_bL_switcher, no_bL_switcher, bool, 0644); | |
559 | ||
6b7437ae NP |
560 | static int __init bL_switcher_init(void) |
561 | { | |
562 | int ret; | |
563 | ||
564 | if (MAX_NR_CLUSTERS != 2) { | |
565 | pr_err("%s: only dual cluster systems are supported\n", __func__); | |
566 | return -EINVAL; | |
567 | } | |
568 | ||
c4821c05 NP |
569 | if (!no_bL_switcher) { |
570 | ret = bL_switcher_enable(); | |
571 | if (ret) | |
572 | return ret; | |
573 | } | |
6b7437ae NP |
574 | |
575 | #ifdef CONFIG_SYSFS | |
576 | ret = bL_switcher_sysfs_init(); | |
577 | if (ret) | |
578 | pr_err("%s: unable to create sysfs entry\n", __func__); | |
579 | #endif | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
71ce1dee | 584 | late_initcall(bL_switcher_init); |