xref: /openbmc/linux/arch/parisc/kernel/smp.c (revision 405db98b) 
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 
34 #include <linux/atomic.h>
35 #include <asm/current.h>
36 #include <asm/delay.h>
37 #include <asm/tlbflush.h>
38 
39 #include <asm/io.h>
40 #include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
41 #include <asm/mmu_context.h>
42 #include <asm/page.h>
43 #include <asm/processor.h>
44 #include <asm/ptrace.h>
45 #include <asm/unistd.h>
46 #include <asm/cacheflush.h>
47 
48 #undef DEBUG_SMP
49 #ifdef DEBUG_SMP
50 static int smp_debug_lvl = 0;
51 #define smp_debug(lvl, printargs...)		\
52 		if (lvl >= smp_debug_lvl)	\
53 			printk(printargs);
54 #else
55 #define smp_debug(lvl, ...)	do { } while(0)
56 #endif /* DEBUG_SMP */
57 
58 volatile struct task_struct *smp_init_current_idle_task;
59 
60 /* track which CPU is booting */
61 static volatile int cpu_now_booting;
62 
63 static int parisc_max_cpus = 1;
64 
65 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
66 
67 enum ipi_message_type {
68 	IPI_NOP=0,
69 	IPI_RESCHEDULE=1,
70 	IPI_CALL_FUNC,
71 	IPI_CPU_START,
72 	IPI_CPU_STOP,
73 	IPI_CPU_TEST,
74 #ifdef CONFIG_KGDB
75 	IPI_ENTER_KGDB,
76 #endif
77 };
78 
79 
80 /********** SMP inter processor interrupt and communication routines */
81 
82 #undef PER_CPU_IRQ_REGION
83 #ifdef PER_CPU_IRQ_REGION
84 /* XXX REVISIT Ignore for now.
85 **    *May* need this "hook" to register IPI handler
86 **    once we have perCPU ExtIntr switch tables.
87 */
88 static void
89 ipi_init(int cpuid)
90 {
91 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
92 
93 	if(cpu_online(cpuid) )
94 	{
95 		switch_to_idle_task(current);
96 	}
97 
98 	return;
99 }
100 #endif
101 
102 
103 /*
104 ** Yoink this CPU from the runnable list...
105 **
106 */
107 static void
108 halt_processor(void)
109 {
110 	/* REVISIT : redirect I/O Interrupts to another CPU? */
111 	/* REVISIT : does PM *know* this CPU isn't available? */
112 	set_cpu_online(smp_processor_id(), false);
113 	local_irq_disable();
114 	__pdc_cpu_rendezvous();
115 	for (;;)
116 		;
117 }
118 
119 
120 irqreturn_t __irq_entry
121 ipi_interrupt(int irq, void *dev_id)
122 {
123 	int this_cpu = smp_processor_id();
124 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
125 	unsigned long ops;
126 	unsigned long flags;
127 
128 	for (;;) {
129 		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
130 		spin_lock_irqsave(lock, flags);
131 		ops = p->pending_ipi;
132 		p->pending_ipi = 0;
133 		spin_unlock_irqrestore(lock, flags);
134 
135 		mb(); /* Order bit clearing and data access. */
136 
137 		if (!ops)
138 		    break;
139 
140 		while (ops) {
141 			unsigned long which = ffz(~ops);
142 
143 			ops &= ~(1 << which);
144 
145 			switch (which) {
146 			case IPI_NOP:
147 				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
148 				break;
149 
150 			case IPI_RESCHEDULE:
151 				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
152 				inc_irq_stat(irq_resched_count);
153 				scheduler_ipi();
154 				break;
155 
156 			case IPI_CALL_FUNC:
157 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
158 				inc_irq_stat(irq_call_count);
159 				generic_smp_call_function_interrupt();
160 				break;
161 
162 			case IPI_CPU_START:
163 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
164 				break;
165 
166 			case IPI_CPU_STOP:
167 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
168 				halt_processor();
169 				break;
170 
171 			case IPI_CPU_TEST:
172 				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
173 				break;
174 #ifdef CONFIG_KGDB
175 			case IPI_ENTER_KGDB:
176 				smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
177 				kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
178 				break;
179 #endif
180 			default:
181 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
182 					this_cpu, which);
183 				return IRQ_NONE;
184 			} /* Switch */
185 
186 			/* before doing more, let in any pending interrupts */
187 			if (ops) {
188 				local_irq_enable();
189 				local_irq_disable();
190 			}
191 		} /* while (ops) */
192 	}
193 	return IRQ_HANDLED;
194 }
195 
196 
197 static inline void
198 ipi_send(int cpu, enum ipi_message_type op)
199 {
200 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
201 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
202 	unsigned long flags;
203 
204 	spin_lock_irqsave(lock, flags);
205 	p->pending_ipi |= 1 << op;
206 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
207 	spin_unlock_irqrestore(lock, flags);
208 }
209 
210 static void
211 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
212 {
213 	int cpu;
214 
215 	for_each_cpu(cpu, mask)
216 		ipi_send(cpu, op);
217 }
218 
219 static inline void
220 send_IPI_single(int dest_cpu, enum ipi_message_type op)
221 {
222 	BUG_ON(dest_cpu == NO_PROC_ID);
223 
224 	ipi_send(dest_cpu, op);
225 }
226 
227 static inline void
228 send_IPI_allbutself(enum ipi_message_type op)
229 {
230 	int i;
231 
232 	preempt_disable();
233 	for_each_online_cpu(i) {
234 		if (i != smp_processor_id())
235 			send_IPI_single(i, op);
236 	}
237 	preempt_enable();
238 }
239 
240 #ifdef CONFIG_KGDB
241 void kgdb_roundup_cpus(void)
242 {
243 	send_IPI_allbutself(IPI_ENTER_KGDB);
244 }
245 #endif
246 
247 inline void
248 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
249 
250 void
251 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
252 
253 void
254 smp_send_all_nop(void)
255 {
256 	send_IPI_allbutself(IPI_NOP);
257 }
258 
259 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
260 {
261 	send_IPI_mask(mask, IPI_CALL_FUNC);
262 }
263 
264 void arch_send_call_function_single_ipi(int cpu)
265 {
266 	send_IPI_single(cpu, IPI_CALL_FUNC);
267 }
268 
269 /*
270  * Called by secondaries to update state and initialize CPU registers.
271  */
272 static void __init
273 smp_cpu_init(int cpunum)
274 {
275 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
276 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
277 
278 	/* Set modes and Enable floating point coprocessor */
279 	init_per_cpu(cpunum);
280 
281 	disable_sr_hashing();
282 
283 	mb();
284 
285 	/* Well, support 2.4 linux scheme as well. */
286 	if (cpu_online(cpunum))	{
287 		extern void machine_halt(void); /* arch/parisc.../process.c */
288 
289 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
290 		machine_halt();
291 	}
292 
293 	notify_cpu_starting(cpunum);
294 
295 	set_cpu_online(cpunum, true);
296 
297 	/* Initialise the idle task for this CPU */
298 	mmgrab(&init_mm);
299 	current->active_mm = &init_mm;
300 	BUG_ON(current->mm);
301 	enter_lazy_tlb(&init_mm, current);
302 
303 	init_IRQ();   /* make sure no IRQs are enabled or pending */
304 	start_cpu_itimer();
305 }
306 
307 
308 /*
309  * Slaves start using C here. Indirectly called from smp_slave_stext.
310  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
311  */
312 void __init smp_callin(unsigned long pdce_proc)
313 {
314 	int slave_id = cpu_now_booting;
315 
316 #ifdef CONFIG_64BIT
317 	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
318 			| PAGE0->mem_pdc) != pdce_proc);
319 #endif
320 
321 	smp_cpu_init(slave_id);
322 
323 	flush_cache_all_local(); /* start with known state */
324 	flush_tlb_all_local(NULL);
325 
326 	local_irq_enable();  /* Interrupts have been off until now */
327 
328 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
329 
330 	/* NOTREACHED */
331 	panic("smp_callin() AAAAaaaaahhhh....\n");
332 }
333 
334 /*
335  * Bring one cpu online.
336  */
337 int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
338 {
339 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
340 	long timeout;
341 
342 	/* Let _start know what logical CPU we're booting
343 	** (offset into init_tasks[],cpu_data[])
344 	*/
345 	cpu_now_booting = cpuid;
346 
347 	/*
348 	** boot strap code needs to know the task address since
349 	** it also contains the process stack.
350 	*/
351 	smp_init_current_idle_task = idle ;
352 	mb();
353 
354 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
355 
356 	/*
357 	** This gets PDC to release the CPU from a very tight loop.
358 	**
359 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
360 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
361 	** is executed after receiving the rendezvous signal (an interrupt to
362 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
363 	** contents of memory are valid."
364 	*/
365 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
366 	mb();
367 
368 	/*
369 	 * OK, wait a bit for that CPU to finish staggering about.
370 	 * Slave will set a bit when it reaches smp_cpu_init().
371 	 * Once the "monarch CPU" sees the bit change, it can move on.
372 	 */
373 	for (timeout = 0; timeout < 10000; timeout++) {
374 		if(cpu_online(cpuid)) {
375 			/* Which implies Slave has started up */
376 			cpu_now_booting = 0;
377 			smp_init_current_idle_task = NULL;
378 			goto alive ;
379 		}
380 		udelay(100);
381 		barrier();
382 	}
383 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
384 	return -1;
385 
386 alive:
387 	/* Remember the Slave data */
388 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
389 		cpuid, timeout * 100);
390 	return 0;
391 }
392 
393 void __init smp_prepare_boot_cpu(void)
394 {
395 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
396 
397 	/* Setup BSP mappings */
398 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
399 
400 	set_cpu_online(bootstrap_processor, true);
401 	set_cpu_present(bootstrap_processor, true);
402 }
403 
404 
405 
406 /*
407 ** inventory.c:do_inventory() hasn't yet been run and thus we
408 ** don't 'discover' the additional CPUs until later.
409 */
410 void __init smp_prepare_cpus(unsigned int max_cpus)
411 {
412 	int cpu;
413 
414 	for_each_possible_cpu(cpu)
415 		spin_lock_init(&per_cpu(ipi_lock, cpu));
416 
417 	init_cpu_present(cpumask_of(0));
418 
419 	parisc_max_cpus = max_cpus;
420 	if (!max_cpus)
421 		printk(KERN_INFO "SMP mode deactivated.\n");
422 }
423 
424 
425 void smp_cpus_done(unsigned int cpu_max)
426 {
427 	return;
428 }
429 
430 
431 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
432 {
433 	if (cpu != 0 && cpu < parisc_max_cpus && smp_boot_one_cpu(cpu, tidle))
434 		return -ENOSYS;
435 
436 	return cpu_online(cpu) ? 0 : -ENOSYS;
437 }
438 
439 #ifdef CONFIG_PROC_FS
440 int setup_profiling_timer(unsigned int multiplier)
441 {
442 	return -EINVAL;
443 }
444 #endif
445