1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2013 Imagination Technologies
4 * Author: Paul Burton <paul.burton@mips.com>
5 */
6
7 #include <linux/cpu.h>
8 #include <linux/delay.h>
9 #include <linux/io.h>
10 #include <linux/sched/task_stack.h>
11 #include <linux/sched/hotplug.h>
12 #include <linux/slab.h>
13 #include <linux/smp.h>
14 #include <linux/types.h>
15 #include <linux/irq.h>
16
17 #include <asm/bcache.h>
18 #include <asm/mips-cps.h>
19 #include <asm/mips_mt.h>
20 #include <asm/mipsregs.h>
21 #include <asm/pm-cps.h>
22 #include <asm/r4kcache.h>
23 #include <asm/smp-cps.h>
24 #include <asm/time.h>
25 #include <asm/uasm.h>
26
27 static bool threads_disabled;
28 static DECLARE_BITMAP(core_power, NR_CPUS);
29
30 struct core_boot_config *mips_cps_core_bootcfg;
31
setup_nothreads(char * s)32 static int __init setup_nothreads(char *s)
33 {
34 threads_disabled = true;
35 return 0;
36 }
37 early_param("nothreads", setup_nothreads);
38
core_vpe_count(unsigned int cluster,unsigned core)39 static unsigned core_vpe_count(unsigned int cluster, unsigned core)
40 {
41 if (threads_disabled)
42 return 1;
43
44 return mips_cps_numvps(cluster, core);
45 }
46
cps_smp_setup(void)47 static void __init cps_smp_setup(void)
48 {
49 unsigned int nclusters, ncores, nvpes, core_vpes;
50 unsigned long core_entry;
51 int cl, c, v;
52
53 /* Detect & record VPE topology */
54 nvpes = 0;
55 nclusters = mips_cps_numclusters();
56 pr_info("%s topology ", cpu_has_mips_r6 ? "VP" : "VPE");
57 for (cl = 0; cl < nclusters; cl++) {
58 if (cl > 0)
59 pr_cont(",");
60 pr_cont("{");
61
62 ncores = mips_cps_numcores(cl);
63 for (c = 0; c < ncores; c++) {
64 core_vpes = core_vpe_count(cl, c);
65
66 if (c > 0)
67 pr_cont(",");
68 pr_cont("%u", core_vpes);
69
70 /* Use the number of VPEs in cluster 0 core 0 for smp_num_siblings */
71 if (!cl && !c)
72 smp_num_siblings = core_vpes;
73
74 for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {
75 cpu_set_cluster(&cpu_data[nvpes + v], cl);
76 cpu_set_core(&cpu_data[nvpes + v], c);
77 cpu_set_vpe_id(&cpu_data[nvpes + v], v);
78 }
79
80 nvpes += core_vpes;
81 }
82
83 pr_cont("}");
84 }
85 pr_cont(" total %u\n", nvpes);
86
87 /* Indicate present CPUs (CPU being synonymous with VPE) */
88 for (v = 0; v < min_t(unsigned, nvpes, NR_CPUS); v++) {
89 set_cpu_possible(v, cpu_cluster(&cpu_data[v]) == 0);
90 set_cpu_present(v, cpu_cluster(&cpu_data[v]) == 0);
91 __cpu_number_map[v] = v;
92 __cpu_logical_map[v] = v;
93 }
94
95 /* Set a coherent default CCA (CWB) */
96 change_c0_config(CONF_CM_CMASK, 0x5);
97
98 /* Core 0 is powered up (we're running on it) */
99 bitmap_set(core_power, 0, 1);
100
101 /* Initialise core 0 */
102 mips_cps_core_init();
103
104 /* Make core 0 coherent with everything */
105 write_gcr_cl_coherence(0xff);
106
107 if (mips_cm_revision() >= CM_REV_CM3) {
108 core_entry = CKSEG1ADDR((unsigned long)mips_cps_core_entry);
109 write_gcr_bev_base(core_entry);
110 }
111
112 #ifdef CONFIG_MIPS_MT_FPAFF
113 /* If we have an FPU, enroll ourselves in the FPU-full mask */
114 if (cpu_has_fpu)
115 cpumask_set_cpu(0, &mt_fpu_cpumask);
116 #endif /* CONFIG_MIPS_MT_FPAFF */
117 }
118
cps_prepare_cpus(unsigned int max_cpus)119 static void __init cps_prepare_cpus(unsigned int max_cpus)
120 {
121 unsigned ncores, core_vpes, c, cca;
122 bool cca_unsuitable, cores_limited;
123 u32 *entry_code;
124
125 mips_mt_set_cpuoptions();
126
127 /* Detect whether the CCA is unsuited to multi-core SMP */
128 cca = read_c0_config() & CONF_CM_CMASK;
129 switch (cca) {
130 case 0x4: /* CWBE */
131 case 0x5: /* CWB */
132 /* The CCA is coherent, multi-core is fine */
133 cca_unsuitable = false;
134 break;
135
136 default:
137 /* CCA is not coherent, multi-core is not usable */
138 cca_unsuitable = true;
139 }
140
141 /* Warn the user if the CCA prevents multi-core */
142 cores_limited = false;
143 if (cca_unsuitable || cpu_has_dc_aliases) {
144 for_each_present_cpu(c) {
145 if (cpus_are_siblings(smp_processor_id(), c))
146 continue;
147
148 set_cpu_present(c, false);
149 cores_limited = true;
150 }
151 }
152 if (cores_limited)
153 pr_warn("Using only one core due to %s%s%s\n",
154 cca_unsuitable ? "unsuitable CCA" : "",
155 (cca_unsuitable && cpu_has_dc_aliases) ? " & " : "",
156 cpu_has_dc_aliases ? "dcache aliasing" : "");
157
158 /*
159 * Patch the start of mips_cps_core_entry to provide:
160 *
161 * s0 = kseg0 CCA
162 */
163 entry_code = (u32 *)&mips_cps_core_entry;
164 uasm_i_addiu(&entry_code, 16, 0, cca);
165 blast_dcache_range((unsigned long)&mips_cps_core_entry,
166 (unsigned long)entry_code);
167 bc_wback_inv((unsigned long)&mips_cps_core_entry,
168 (void *)entry_code - (void *)&mips_cps_core_entry);
169 __sync();
170
171 /* Allocate core boot configuration structs */
172 ncores = mips_cps_numcores(0);
173 mips_cps_core_bootcfg = kcalloc(ncores, sizeof(*mips_cps_core_bootcfg),
174 GFP_KERNEL);
175 if (!mips_cps_core_bootcfg) {
176 pr_err("Failed to allocate boot config for %u cores\n", ncores);
177 goto err_out;
178 }
179
180 /* Allocate VPE boot configuration structs */
181 for (c = 0; c < ncores; c++) {
182 core_vpes = core_vpe_count(0, c);
183 mips_cps_core_bootcfg[c].vpe_config = kcalloc(core_vpes,
184 sizeof(*mips_cps_core_bootcfg[c].vpe_config),
185 GFP_KERNEL);
186 if (!mips_cps_core_bootcfg[c].vpe_config) {
187 pr_err("Failed to allocate %u VPE boot configs\n",
188 core_vpes);
189 goto err_out;
190 }
191 }
192
193 /* Mark this CPU as booted */
194 atomic_set(&mips_cps_core_bootcfg[cpu_core(¤t_cpu_data)].vpe_mask,
195 1 << cpu_vpe_id(¤t_cpu_data));
196
197 return;
198 err_out:
199 /* Clean up allocations */
200 if (mips_cps_core_bootcfg) {
201 for (c = 0; c < ncores; c++)
202 kfree(mips_cps_core_bootcfg[c].vpe_config);
203 kfree(mips_cps_core_bootcfg);
204 mips_cps_core_bootcfg = NULL;
205 }
206
207 /* Effectively disable SMP by declaring CPUs not present */
208 for_each_possible_cpu(c) {
209 if (c == 0)
210 continue;
211 set_cpu_present(c, false);
212 }
213 }
214
boot_core(unsigned int core,unsigned int vpe_id)215 static void boot_core(unsigned int core, unsigned int vpe_id)
216 {
217 u32 stat, seq_state;
218 unsigned timeout;
219
220 /* Select the appropriate core */
221 mips_cm_lock_other(0, core, 0, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
222
223 /* Set its reset vector */
224 write_gcr_co_reset_base(CKSEG1ADDR((unsigned long)mips_cps_core_entry));
225
226 /* Ensure its coherency is disabled */
227 write_gcr_co_coherence(0);
228
229 /* Start it with the legacy memory map and exception base */
230 write_gcr_co_reset_ext_base(CM_GCR_Cx_RESET_EXT_BASE_UEB);
231
232 /* Ensure the core can access the GCRs */
233 set_gcr_access(1 << core);
234
235 if (mips_cpc_present()) {
236 /* Reset the core */
237 mips_cpc_lock_other(core);
238
239 if (mips_cm_revision() >= CM_REV_CM3) {
240 /* Run only the requested VP following the reset */
241 write_cpc_co_vp_stop(0xf);
242 write_cpc_co_vp_run(1 << vpe_id);
243
244 /*
245 * Ensure that the VP_RUN register is written before the
246 * core leaves reset.
247 */
248 wmb();
249 }
250
251 write_cpc_co_cmd(CPC_Cx_CMD_RESET);
252
253 timeout = 100;
254 while (true) {
255 stat = read_cpc_co_stat_conf();
256 seq_state = stat & CPC_Cx_STAT_CONF_SEQSTATE;
257 seq_state >>= __ffs(CPC_Cx_STAT_CONF_SEQSTATE);
258
259 /* U6 == coherent execution, ie. the core is up */
260 if (seq_state == CPC_Cx_STAT_CONF_SEQSTATE_U6)
261 break;
262
263 /* Delay a little while before we start warning */
264 if (timeout) {
265 timeout--;
266 mdelay(10);
267 continue;
268 }
269
270 pr_warn("Waiting for core %u to start... STAT_CONF=0x%x\n",
271 core, stat);
272 mdelay(1000);
273 }
274
275 mips_cpc_unlock_other();
276 } else {
277 /* Take the core out of reset */
278 write_gcr_co_reset_release(0);
279 }
280
281 mips_cm_unlock_other();
282
283 /* The core is now powered up */
284 bitmap_set(core_power, core, 1);
285 }
286
remote_vpe_boot(void * dummy)287 static void remote_vpe_boot(void *dummy)
288 {
289 unsigned core = cpu_core(¤t_cpu_data);
290 struct core_boot_config *core_cfg = &mips_cps_core_bootcfg[core];
291
292 mips_cps_boot_vpes(core_cfg, cpu_vpe_id(¤t_cpu_data));
293 }
294
cps_boot_secondary(int cpu,struct task_struct * idle)295 static int cps_boot_secondary(int cpu, struct task_struct *idle)
296 {
297 unsigned core = cpu_core(&cpu_data[cpu]);
298 unsigned vpe_id = cpu_vpe_id(&cpu_data[cpu]);
299 struct core_boot_config *core_cfg = &mips_cps_core_bootcfg[core];
300 struct vpe_boot_config *vpe_cfg = &core_cfg->vpe_config[vpe_id];
301 unsigned long core_entry;
302 unsigned int remote;
303 int err;
304
305 /* We don't yet support booting CPUs in other clusters */
306 if (cpu_cluster(&cpu_data[cpu]) != cpu_cluster(&raw_current_cpu_data))
307 return -ENOSYS;
308
309 vpe_cfg->pc = (unsigned long)&smp_bootstrap;
310 vpe_cfg->sp = __KSTK_TOS(idle);
311 vpe_cfg->gp = (unsigned long)task_thread_info(idle);
312
313 atomic_or(1 << cpu_vpe_id(&cpu_data[cpu]), &core_cfg->vpe_mask);
314
315 preempt_disable();
316
317 if (!test_bit(core, core_power)) {
318 /* Boot a VPE on a powered down core */
319 boot_core(core, vpe_id);
320 goto out;
321 }
322
323 if (cpu_has_vp) {
324 mips_cm_lock_other(0, core, vpe_id, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
325 core_entry = CKSEG1ADDR((unsigned long)mips_cps_core_entry);
326 write_gcr_co_reset_base(core_entry);
327 mips_cm_unlock_other();
328 }
329
330 if (!cpus_are_siblings(cpu, smp_processor_id())) {
331 /* Boot a VPE on another powered up core */
332 for (remote = 0; remote < NR_CPUS; remote++) {
333 if (!cpus_are_siblings(cpu, remote))
334 continue;
335 if (cpu_online(remote))
336 break;
337 }
338 if (remote >= NR_CPUS) {
339 pr_crit("No online CPU in core %u to start CPU%d\n",
340 core, cpu);
341 goto out;
342 }
343
344 err = smp_call_function_single(remote, remote_vpe_boot,
345 NULL, 1);
346 if (err)
347 panic("Failed to call remote CPU\n");
348 goto out;
349 }
350
351 BUG_ON(!cpu_has_mipsmt && !cpu_has_vp);
352
353 /* Boot a VPE on this core */
354 mips_cps_boot_vpes(core_cfg, vpe_id);
355 out:
356 preempt_enable();
357 return 0;
358 }
359
cps_init_secondary(void)360 static void cps_init_secondary(void)
361 {
362 /* Disable MT - we only want to run 1 TC per VPE */
363 if (cpu_has_mipsmt)
364 dmt();
365
366 if (mips_cm_revision() >= CM_REV_CM3) {
367 unsigned int ident = read_gic_vl_ident();
368
369 /*
370 * Ensure that our calculation of the VP ID matches up with
371 * what the GIC reports, otherwise we'll have configured
372 * interrupts incorrectly.
373 */
374 BUG_ON(ident != mips_cm_vp_id(smp_processor_id()));
375 }
376
377 if (cpu_has_veic)
378 clear_c0_status(ST0_IM);
379 else
380 change_c0_status(ST0_IM, STATUSF_IP2 | STATUSF_IP3 |
381 STATUSF_IP4 | STATUSF_IP5 |
382 STATUSF_IP6 | STATUSF_IP7);
383 }
384
cps_smp_finish(void)385 static void cps_smp_finish(void)
386 {
387 write_c0_compare(read_c0_count() + (8 * mips_hpt_frequency / HZ));
388
389 #ifdef CONFIG_MIPS_MT_FPAFF
390 /* If we have an FPU, enroll ourselves in the FPU-full mask */
391 if (cpu_has_fpu)
392 cpumask_set_cpu(smp_processor_id(), &mt_fpu_cpumask);
393 #endif /* CONFIG_MIPS_MT_FPAFF */
394
395 local_irq_enable();
396 }
397
398 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_KEXEC)
399
400 enum cpu_death {
401 CPU_DEATH_HALT,
402 CPU_DEATH_POWER,
403 };
404
cps_shutdown_this_cpu(enum cpu_death death)405 static void cps_shutdown_this_cpu(enum cpu_death death)
406 {
407 unsigned int cpu, core, vpe_id;
408
409 cpu = smp_processor_id();
410 core = cpu_core(&cpu_data[cpu]);
411
412 if (death == CPU_DEATH_HALT) {
413 vpe_id = cpu_vpe_id(&cpu_data[cpu]);
414
415 pr_debug("Halting core %d VP%d\n", core, vpe_id);
416 if (cpu_has_mipsmt) {
417 /* Halt this TC */
418 write_c0_tchalt(TCHALT_H);
419 instruction_hazard();
420 } else if (cpu_has_vp) {
421 write_cpc_cl_vp_stop(1 << vpe_id);
422
423 /* Ensure that the VP_STOP register is written */
424 wmb();
425 }
426 } else {
427 pr_debug("Gating power to core %d\n", core);
428 /* Power down the core */
429 cps_pm_enter_state(CPS_PM_POWER_GATED);
430 }
431 }
432
433 #ifdef CONFIG_KEXEC
434
cps_kexec_nonboot_cpu(void)435 static void cps_kexec_nonboot_cpu(void)
436 {
437 if (cpu_has_mipsmt || cpu_has_vp)
438 cps_shutdown_this_cpu(CPU_DEATH_HALT);
439 else
440 cps_shutdown_this_cpu(CPU_DEATH_POWER);
441 }
442
443 #endif /* CONFIG_KEXEC */
444
445 #endif /* CONFIG_HOTPLUG_CPU || CONFIG_KEXEC */
446
447 #ifdef CONFIG_HOTPLUG_CPU
448
cps_cpu_disable(void)449 static int cps_cpu_disable(void)
450 {
451 unsigned cpu = smp_processor_id();
452 struct core_boot_config *core_cfg;
453
454 if (!cps_pm_support_state(CPS_PM_POWER_GATED))
455 return -EINVAL;
456
457 core_cfg = &mips_cps_core_bootcfg[cpu_core(¤t_cpu_data)];
458 atomic_sub(1 << cpu_vpe_id(¤t_cpu_data), &core_cfg->vpe_mask);
459 smp_mb__after_atomic();
460 set_cpu_online(cpu, false);
461 calculate_cpu_foreign_map();
462 irq_migrate_all_off_this_cpu();
463
464 return 0;
465 }
466
467 static unsigned cpu_death_sibling;
468 static enum cpu_death cpu_death;
469
play_dead(void)470 void play_dead(void)
471 {
472 unsigned int cpu;
473
474 local_irq_disable();
475 idle_task_exit();
476 cpu = smp_processor_id();
477 cpu_death = CPU_DEATH_POWER;
478
479 pr_debug("CPU%d going offline\n", cpu);
480
481 if (cpu_has_mipsmt || cpu_has_vp) {
482 /* Look for another online VPE within the core */
483 for_each_online_cpu(cpu_death_sibling) {
484 if (!cpus_are_siblings(cpu, cpu_death_sibling))
485 continue;
486
487 /*
488 * There is an online VPE within the core. Just halt
489 * this TC and leave the core alone.
490 */
491 cpu_death = CPU_DEATH_HALT;
492 break;
493 }
494 }
495
496 /* This CPU has chosen its way out */
497 (void)cpu_report_death();
498
499 cps_shutdown_this_cpu(cpu_death);
500
501 /* This should never be reached */
502 panic("Failed to offline CPU %u", cpu);
503 }
504
wait_for_sibling_halt(void * ptr_cpu)505 static void wait_for_sibling_halt(void *ptr_cpu)
506 {
507 unsigned cpu = (unsigned long)ptr_cpu;
508 unsigned vpe_id = cpu_vpe_id(&cpu_data[cpu]);
509 unsigned halted;
510 unsigned long flags;
511
512 do {
513 local_irq_save(flags);
514 settc(vpe_id);
515 halted = read_tc_c0_tchalt();
516 local_irq_restore(flags);
517 } while (!(halted & TCHALT_H));
518 }
519
cps_cpu_die(unsigned int cpu)520 static void cps_cpu_die(unsigned int cpu)
521 {
522 unsigned core = cpu_core(&cpu_data[cpu]);
523 unsigned int vpe_id = cpu_vpe_id(&cpu_data[cpu]);
524 ktime_t fail_time;
525 unsigned stat;
526 int err;
527
528 /* Wait for the cpu to choose its way out */
529 if (!cpu_wait_death(cpu, 5)) {
530 pr_err("CPU%u: didn't offline\n", cpu);
531 return;
532 }
533
534 /*
535 * Now wait for the CPU to actually offline. Without doing this that
536 * offlining may race with one or more of:
537 *
538 * - Onlining the CPU again.
539 * - Powering down the core if another VPE within it is offlined.
540 * - A sibling VPE entering a non-coherent state.
541 *
542 * In the non-MT halt case (ie. infinite loop) the CPU is doing nothing
543 * with which we could race, so do nothing.
544 */
545 if (cpu_death == CPU_DEATH_POWER) {
546 /*
547 * Wait for the core to enter a powered down or clock gated
548 * state, the latter happening when a JTAG probe is connected
549 * in which case the CPC will refuse to power down the core.
550 */
551 fail_time = ktime_add_ms(ktime_get(), 2000);
552 do {
553 mips_cm_lock_other(0, core, 0, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
554 mips_cpc_lock_other(core);
555 stat = read_cpc_co_stat_conf();
556 stat &= CPC_Cx_STAT_CONF_SEQSTATE;
557 stat >>= __ffs(CPC_Cx_STAT_CONF_SEQSTATE);
558 mips_cpc_unlock_other();
559 mips_cm_unlock_other();
560
561 if (stat == CPC_Cx_STAT_CONF_SEQSTATE_D0 ||
562 stat == CPC_Cx_STAT_CONF_SEQSTATE_D2 ||
563 stat == CPC_Cx_STAT_CONF_SEQSTATE_U2)
564 break;
565
566 /*
567 * The core ought to have powered down, but didn't &
568 * now we don't really know what state it's in. It's
569 * likely that its _pwr_up pin has been wired to logic
570 * 1 & it powered back up as soon as we powered it
571 * down...
572 *
573 * The best we can do is warn the user & continue in
574 * the hope that the core is doing nothing harmful &
575 * might behave properly if we online it later.
576 */
577 if (WARN(ktime_after(ktime_get(), fail_time),
578 "CPU%u hasn't powered down, seq. state %u\n",
579 cpu, stat))
580 break;
581 } while (1);
582
583 /* Indicate the core is powered off */
584 bitmap_clear(core_power, core, 1);
585 } else if (cpu_has_mipsmt) {
586 /*
587 * Have a CPU with access to the offlined CPUs registers wait
588 * for its TC to halt.
589 */
590 err = smp_call_function_single(cpu_death_sibling,
591 wait_for_sibling_halt,
592 (void *)(unsigned long)cpu, 1);
593 if (err)
594 panic("Failed to call remote sibling CPU\n");
595 } else if (cpu_has_vp) {
596 do {
597 mips_cm_lock_other(0, core, vpe_id, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
598 stat = read_cpc_co_vp_running();
599 mips_cm_unlock_other();
600 } while (stat & (1 << vpe_id));
601 }
602 }
603
604 #endif /* CONFIG_HOTPLUG_CPU */
605
606 static const struct plat_smp_ops cps_smp_ops = {
607 .smp_setup = cps_smp_setup,
608 .prepare_cpus = cps_prepare_cpus,
609 .boot_secondary = cps_boot_secondary,
610 .init_secondary = cps_init_secondary,
611 .smp_finish = cps_smp_finish,
612 .send_ipi_single = mips_smp_send_ipi_single,
613 .send_ipi_mask = mips_smp_send_ipi_mask,
614 #ifdef CONFIG_HOTPLUG_CPU
615 .cpu_disable = cps_cpu_disable,
616 .cpu_die = cps_cpu_die,
617 #endif
618 #ifdef CONFIG_KEXEC
619 .kexec_nonboot_cpu = cps_kexec_nonboot_cpu,
620 #endif
621 };
622
mips_cps_smp_in_use(void)623 bool mips_cps_smp_in_use(void)
624 {
625 extern const struct plat_smp_ops *mp_ops;
626 return mp_ops == &cps_smp_ops;
627 }
628
register_cps_smp_ops(void)629 int register_cps_smp_ops(void)
630 {
631 if (!mips_cm_present()) {
632 pr_warn("MIPS CPS SMP unable to proceed without a CM\n");
633 return -ENODEV;
634 }
635
636 /* check we have a GIC - we need one for IPIs */
637 if (!(read_gcr_gic_status() & CM_GCR_GIC_STATUS_EX)) {
638 pr_warn("MIPS CPS SMP unable to proceed without a GIC\n");
639 return -ENODEV;
640 }
641
642 register_smp_ops(&cps_smp_ops);
643 return 0;
644 }
645