xref: /openbmc/linux/arch/parisc/kernel/smp.c (revision 3bf90eca) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 ** SMP Support
4 **
5 ** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
6 ** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
7 ** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
8 **
9 ** Lots of stuff stolen from arch/alpha/kernel/smp.c
10 ** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
11 **
12 ** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
13 ** -grant (1/12/2001)
14 **
15 */
16 #include <linux/types.h>
17 #include <linux/spinlock.h>
18 
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/sched/mm.h>
22 #include <linux/init.h>
23 #include <linux/interrupt.h>
24 #include <linux/smp.h>
25 #include <linux/kernel_stat.h>
26 #include <linux/mm.h>
27 #include <linux/err.h>
28 #include <linux/delay.h>
29 #include <linux/bitops.h>
30 #include <linux/ftrace.h>
31 #include <linux/cpu.h>
32 #include <linux/kgdb.h>
33 #include <linux/sched/hotplug.h>
34 
35 #include <linux/atomic.h>
36 #include <asm/current.h>
37 #include <asm/delay.h>
38 #include <asm/tlbflush.h>
39 
40 #include <asm/io.h>
41 #include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
42 #include <asm/mmu_context.h>
43 #include <asm/page.h>
44 #include <asm/processor.h>
45 #include <asm/ptrace.h>
46 #include <asm/unistd.h>
47 #include <asm/cacheflush.h>
48 
49 #undef DEBUG_SMP
50 #ifdef DEBUG_SMP
51 static int smp_debug_lvl = 0;
52 #define smp_debug(lvl, printargs...)		\
53 		if (lvl >= smp_debug_lvl)	\
54 			printk(printargs);
55 #else
56 #define smp_debug(lvl, ...)	do { } while(0)
57 #endif /* DEBUG_SMP */
58 
59 volatile struct task_struct *smp_init_current_idle_task;
60 
61 /* track which CPU is booting */
62 static volatile int cpu_now_booting;
63 
64 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
65 
66 enum ipi_message_type {
67 	IPI_NOP=0,
68 	IPI_RESCHEDULE=1,
69 	IPI_CALL_FUNC,
70 	IPI_CPU_START,
71 	IPI_CPU_STOP,
72 	IPI_CPU_TEST,
73 #ifdef CONFIG_KGDB
74 	IPI_ENTER_KGDB,
75 #endif
76 };
77 
78 
79 /********** SMP inter processor interrupt and communication routines */
80 
81 #undef PER_CPU_IRQ_REGION
82 #ifdef PER_CPU_IRQ_REGION
83 /* XXX REVISIT Ignore for now.
84 **    *May* need this "hook" to register IPI handler
85 **    once we have perCPU ExtIntr switch tables.
86 */
87 static void
88 ipi_init(int cpuid)
89 {
90 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
91 
92 	if(cpu_online(cpuid) )
93 	{
94 		switch_to_idle_task(current);
95 	}
96 
97 	return;
98 }
99 #endif
100 
101 
102 /*
103 ** Yoink this CPU from the runnable list...
104 **
105 */
106 static void
107 halt_processor(void)
108 {
109 	/* REVISIT : redirect I/O Interrupts to another CPU? */
110 	/* REVISIT : does PM *know* this CPU isn't available? */
111 	set_cpu_online(smp_processor_id(), false);
112 	local_irq_disable();
113 	__pdc_cpu_rendezvous();
114 	for (;;)
115 		;
116 }
117 
118 
119 irqreturn_t __irq_entry
120 ipi_interrupt(int irq, void *dev_id)
121 {
122 	int this_cpu = smp_processor_id();
123 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
124 	unsigned long ops;
125 	unsigned long flags;
126 
127 	for (;;) {
128 		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
129 		spin_lock_irqsave(lock, flags);
130 		ops = p->pending_ipi;
131 		p->pending_ipi = 0;
132 		spin_unlock_irqrestore(lock, flags);
133 
134 		mb(); /* Order bit clearing and data access. */
135 
136 		if (!ops)
137 		    break;
138 
139 		while (ops) {
140 			unsigned long which = ffz(~ops);
141 
142 			ops &= ~(1 << which);
143 
144 			switch (which) {
145 			case IPI_NOP:
146 				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
147 				break;
148 
149 			case IPI_RESCHEDULE:
150 				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
151 				inc_irq_stat(irq_resched_count);
152 				scheduler_ipi();
153 				break;
154 
155 			case IPI_CALL_FUNC:
156 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
157 				inc_irq_stat(irq_call_count);
158 				generic_smp_call_function_interrupt();
159 				break;
160 
161 			case IPI_CPU_START:
162 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
163 				break;
164 
165 			case IPI_CPU_STOP:
166 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
167 				halt_processor();
168 				break;
169 
170 			case IPI_CPU_TEST:
171 				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
172 				break;
173 #ifdef CONFIG_KGDB
174 			case IPI_ENTER_KGDB:
175 				smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
176 				kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
177 				break;
178 #endif
179 			default:
180 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
181 					this_cpu, which);
182 				return IRQ_NONE;
183 			} /* Switch */
184 
185 			/* before doing more, let in any pending interrupts */
186 			if (ops) {
187 				local_irq_enable();
188 				local_irq_disable();
189 			}
190 		} /* while (ops) */
191 	}
192 	return IRQ_HANDLED;
193 }
194 
195 
196 static inline void
197 ipi_send(int cpu, enum ipi_message_type op)
198 {
199 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
200 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
201 	unsigned long flags;
202 
203 	spin_lock_irqsave(lock, flags);
204 	p->pending_ipi |= 1 << op;
205 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
206 	spin_unlock_irqrestore(lock, flags);
207 }
208 
209 static void
210 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
211 {
212 	int cpu;
213 
214 	for_each_cpu(cpu, mask)
215 		ipi_send(cpu, op);
216 }
217 
218 static inline void
219 send_IPI_single(int dest_cpu, enum ipi_message_type op)
220 {
221 	BUG_ON(dest_cpu == NO_PROC_ID);
222 
223 	ipi_send(dest_cpu, op);
224 }
225 
226 static inline void
227 send_IPI_allbutself(enum ipi_message_type op)
228 {
229 	int i;
230 
231 	preempt_disable();
232 	for_each_online_cpu(i) {
233 		if (i != smp_processor_id())
234 			send_IPI_single(i, op);
235 	}
236 	preempt_enable();
237 }
238 
239 #ifdef CONFIG_KGDB
240 void kgdb_roundup_cpus(void)
241 {
242 	send_IPI_allbutself(IPI_ENTER_KGDB);
243 }
244 #endif
245 
246 inline void
247 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
248 
249 void
250 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
251 
252 void
253 smp_send_all_nop(void)
254 {
255 	send_IPI_allbutself(IPI_NOP);
256 }
257 
258 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
259 {
260 	send_IPI_mask(mask, IPI_CALL_FUNC);
261 }
262 
263 void arch_send_call_function_single_ipi(int cpu)
264 {
265 	send_IPI_single(cpu, IPI_CALL_FUNC);
266 }
267 
268 /*
269  * Called by secondaries to update state and initialize CPU registers.
270  */
271 static void
272 smp_cpu_init(int cpunum)
273 {
274 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
275 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
276 
277 	/* Set modes and Enable floating point coprocessor */
278 	init_per_cpu(cpunum);
279 
280 	disable_sr_hashing();
281 
282 	mb();
283 
284 	/* Well, support 2.4 linux scheme as well. */
285 	if (cpu_online(cpunum))	{
286 		extern void machine_halt(void); /* arch/parisc.../process.c */
287 
288 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
289 		machine_halt();
290 	}
291 
292 	notify_cpu_starting(cpunum);
293 
294 	set_cpu_online(cpunum, true);
295 
296 	/* Initialise the idle task for this CPU */
297 	mmgrab(&init_mm);
298 	current->active_mm = &init_mm;
299 	BUG_ON(current->mm);
300 	enter_lazy_tlb(&init_mm, current);
301 
302 	init_IRQ();   /* make sure no IRQs are enabled or pending */
303 	start_cpu_itimer();
304 }
305 
306 
307 /*
308  * Slaves start using C here. Indirectly called from smp_slave_stext.
309  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
310  */
311 void smp_callin(unsigned long pdce_proc)
312 {
313 	int slave_id = cpu_now_booting;
314 
315 #ifdef CONFIG_64BIT
316 	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
317 			| PAGE0->mem_pdc) != pdce_proc);
318 #endif
319 
320 	smp_cpu_init(slave_id);
321 
322 	flush_cache_all_local(); /* start with known state */
323 	flush_tlb_all_local(NULL);
324 
325 	local_irq_enable();  /* Interrupts have been off until now */
326 
327 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
328 
329 	/* NOTREACHED */
330 	panic("smp_callin() AAAAaaaaahhhh....\n");
331 }
332 
333 /*
334  * Bring one cpu online.
335  */
336 static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
337 {
338 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
339 	long timeout;
340 
341 #ifdef CONFIG_HOTPLUG_CPU
342 	int i;
343 
344 	/* reset irq statistics for this CPU */
345 	memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
346 	for (i = 0; i < NR_IRQS; i++) {
347 		struct irq_desc *desc = irq_to_desc(i);
348 
349 		if (desc && desc->kstat_irqs)
350 			*per_cpu_ptr(desc->kstat_irqs, cpuid) = 0;
351 	}
352 #endif
353 
354 	/* wait until last booting CPU has started. */
355 	while (cpu_now_booting)
356 		;
357 
358 	/* Let _start know what logical CPU we're booting
359 	** (offset into init_tasks[],cpu_data[])
360 	*/
361 	cpu_now_booting = cpuid;
362 
363 	/*
364 	** boot strap code needs to know the task address since
365 	** it also contains the process stack.
366 	*/
367 	smp_init_current_idle_task = idle ;
368 	mb();
369 
370 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
371 
372 	/*
373 	** This gets PDC to release the CPU from a very tight loop.
374 	**
375 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
376 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
377 	** is executed after receiving the rendezvous signal (an interrupt to
378 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
379 	** contents of memory are valid."
380 	*/
381 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
382 	mb();
383 
384 	/*
385 	 * OK, wait a bit for that CPU to finish staggering about.
386 	 * Slave will set a bit when it reaches smp_cpu_init().
387 	 * Once the "monarch CPU" sees the bit change, it can move on.
388 	 */
389 	for (timeout = 0; timeout < 10000; timeout++) {
390 		if(cpu_online(cpuid)) {
391 			/* Which implies Slave has started up */
392 			cpu_now_booting = 0;
393 			goto alive ;
394 		}
395 		udelay(100);
396 		barrier();
397 	}
398 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
399 	return -1;
400 
401 alive:
402 	/* Remember the Slave data */
403 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
404 		cpuid, timeout * 100);
405 	return 0;
406 }
407 
408 void __init smp_prepare_boot_cpu(void)
409 {
410 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
411 
412 	/* Setup BSP mappings */
413 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
414 
415 	set_cpu_online(bootstrap_processor, true);
416 	set_cpu_present(bootstrap_processor, true);
417 }
418 
419 
420 
421 /*
422 ** inventory.c:do_inventory() hasn't yet been run and thus we
423 ** don't 'discover' the additional CPUs until later.
424 */
425 void __init smp_prepare_cpus(unsigned int max_cpus)
426 {
427 	int cpu;
428 
429 	for_each_possible_cpu(cpu)
430 		spin_lock_init(&per_cpu(ipi_lock, cpu));
431 
432 	init_cpu_present(cpumask_of(0));
433 }
434 
435 
436 void __init smp_cpus_done(unsigned int cpu_max)
437 {
438 }
439 
440 
441 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
442 {
443 	if (cpu_online(cpu))
444 		return 0;
445 
446 	if (num_online_cpus() < setup_max_cpus && smp_boot_one_cpu(cpu, tidle))
447 		return -EIO;
448 
449 	return cpu_online(cpu) ? 0 : -EIO;
450 }
451 
452 /*
453  * __cpu_disable runs on the processor to be shutdown.
454  */
455 int __cpu_disable(void)
456 {
457 #ifdef CONFIG_HOTPLUG_CPU
458 	unsigned int cpu = smp_processor_id();
459 
460 	remove_cpu_topology(cpu);
461 
462 	/*
463 	 * Take this CPU offline.  Once we clear this, we can't return,
464 	 * and we must not schedule until we're ready to give up the cpu.
465 	 */
466 	set_cpu_online(cpu, false);
467 
468 	/* Find a new timesync master */
469 	if (cpu == time_keeper_id) {
470 		time_keeper_id = cpumask_first(cpu_online_mask);
471 		pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
472 	}
473 
474 	disable_percpu_irq(IPI_IRQ);
475 
476 	irq_migrate_all_off_this_cpu();
477 
478 	flush_cache_all_local();
479 	flush_tlb_all_local(NULL);
480 
481 	/* disable all irqs, including timer irq */
482 	local_irq_disable();
483 
484 	/* wait for next timer irq ... */
485 	mdelay(1000/HZ+100);
486 
487 	/* ... and then clear all pending external irqs */
488 	set_eiem(0);
489 	mtctl(~0UL, CR_EIRR);
490 	mfctl(CR_EIRR);
491 	mtctl(0, CR_EIRR);
492 #endif
493 	return 0;
494 }
495 
496 /*
497  * called on the thread which is asking for a CPU to be shutdown -
498  * waits until shutdown has completed, or it is timed out.
499  */
500 void __cpu_die(unsigned int cpu)
501 {
502 	pdc_cpu_rendezvous_lock();
503 
504 	if (!cpu_wait_death(cpu, 5)) {
505 		pr_crit("CPU%u: cpu didn't die\n", cpu);
506 		return;
507 	}
508 	pr_info("CPU%u: is shutting down\n", cpu);
509 
510 	/* set task's state to interruptible sleep */
511 	set_current_state(TASK_INTERRUPTIBLE);
512 	schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
513 
514 	pdc_cpu_rendezvous_unlock();
515 }
516