xref: /openbmc/linux/arch/parisc/kernel/smp.c (revision 20e2fc42) 
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 
33 #include <linux/atomic.h>
34 #include <asm/current.h>
35 #include <asm/delay.h>
36 #include <asm/tlbflush.h>
37 
38 #include <asm/io.h>
39 #include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
40 #include <asm/mmu_context.h>
41 #include <asm/page.h>
42 #include <asm/pgtable.h>
43 #include <asm/pgalloc.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 int parisc_max_cpus = 1;
65 
66 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
67 
68 enum ipi_message_type {
69 	IPI_NOP=0,
70 	IPI_RESCHEDULE=1,
71 	IPI_CALL_FUNC,
72 	IPI_CPU_START,
73 	IPI_CPU_STOP,
74 	IPI_CPU_TEST
75 };
76 
77 
78 /********** SMP inter processor interrupt and communication routines */
79 
80 #undef PER_CPU_IRQ_REGION
81 #ifdef PER_CPU_IRQ_REGION
82 /* XXX REVISIT Ignore for now.
83 **    *May* need this "hook" to register IPI handler
84 **    once we have perCPU ExtIntr switch tables.
85 */
86 static void
87 ipi_init(int cpuid)
88 {
89 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
90 
91 	if(cpu_online(cpuid) )
92 	{
93 		switch_to_idle_task(current);
94 	}
95 
96 	return;
97 }
98 #endif
99 
100 
101 /*
102 ** Yoink this CPU from the runnable list...
103 **
104 */
105 static void
106 halt_processor(void)
107 {
108 	/* REVISIT : redirect I/O Interrupts to another CPU? */
109 	/* REVISIT : does PM *know* this CPU isn't available? */
110 	set_cpu_online(smp_processor_id(), false);
111 	local_irq_disable();
112 	__pdc_cpu_rendezvous();
113 	for (;;)
114 		;
115 }
116 
117 
118 irqreturn_t __irq_entry
119 ipi_interrupt(int irq, void *dev_id)
120 {
121 	int this_cpu = smp_processor_id();
122 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
123 	unsigned long ops;
124 	unsigned long flags;
125 
126 	for (;;) {
127 		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
128 		spin_lock_irqsave(lock, flags);
129 		ops = p->pending_ipi;
130 		p->pending_ipi = 0;
131 		spin_unlock_irqrestore(lock, flags);
132 
133 		mb(); /* Order bit clearing and data access. */
134 
135 		if (!ops)
136 		    break;
137 
138 		while (ops) {
139 			unsigned long which = ffz(~ops);
140 
141 			ops &= ~(1 << which);
142 
143 			switch (which) {
144 			case IPI_NOP:
145 				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
146 				break;
147 
148 			case IPI_RESCHEDULE:
149 				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
150 				inc_irq_stat(irq_resched_count);
151 				scheduler_ipi();
152 				break;
153 
154 			case IPI_CALL_FUNC:
155 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
156 				inc_irq_stat(irq_call_count);
157 				generic_smp_call_function_interrupt();
158 				break;
159 
160 			case IPI_CPU_START:
161 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
162 				break;
163 
164 			case IPI_CPU_STOP:
165 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
166 				halt_processor();
167 				break;
168 
169 			case IPI_CPU_TEST:
170 				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
171 				break;
172 
173 			default:
174 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
175 					this_cpu, which);
176 				return IRQ_NONE;
177 			} /* Switch */
178 		/* let in any pending interrupts */
179 		local_irq_enable();
180 		local_irq_disable();
181 		} /* while (ops) */
182 	}
183 	return IRQ_HANDLED;
184 }
185 
186 
187 static inline void
188 ipi_send(int cpu, enum ipi_message_type op)
189 {
190 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
191 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
192 	unsigned long flags;
193 
194 	spin_lock_irqsave(lock, flags);
195 	p->pending_ipi |= 1 << op;
196 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
197 	spin_unlock_irqrestore(lock, flags);
198 }
199 
200 static void
201 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
202 {
203 	int cpu;
204 
205 	for_each_cpu(cpu, mask)
206 		ipi_send(cpu, op);
207 }
208 
209 static inline void
210 send_IPI_single(int dest_cpu, enum ipi_message_type op)
211 {
212 	BUG_ON(dest_cpu == NO_PROC_ID);
213 
214 	ipi_send(dest_cpu, op);
215 }
216 
217 static inline void
218 send_IPI_allbutself(enum ipi_message_type op)
219 {
220 	int i;
221 
222 	for_each_online_cpu(i) {
223 		if (i != smp_processor_id())
224 			send_IPI_single(i, op);
225 	}
226 }
227 
228 
229 inline void
230 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
231 
232 void
233 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
234 
235 void
236 smp_send_all_nop(void)
237 {
238 	send_IPI_allbutself(IPI_NOP);
239 }
240 
241 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
242 {
243 	send_IPI_mask(mask, IPI_CALL_FUNC);
244 }
245 
246 void arch_send_call_function_single_ipi(int cpu)
247 {
248 	send_IPI_single(cpu, IPI_CALL_FUNC);
249 }
250 
251 /*
252  * Called by secondaries to update state and initialize CPU registers.
253  */
254 static void __init
255 smp_cpu_init(int cpunum)
256 {
257 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
258 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
259 
260 	/* Set modes and Enable floating point coprocessor */
261 	init_per_cpu(cpunum);
262 
263 	disable_sr_hashing();
264 
265 	mb();
266 
267 	/* Well, support 2.4 linux scheme as well. */
268 	if (cpu_online(cpunum))	{
269 		extern void machine_halt(void); /* arch/parisc.../process.c */
270 
271 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
272 		machine_halt();
273 	}
274 
275 	notify_cpu_starting(cpunum);
276 
277 	set_cpu_online(cpunum, true);
278 
279 	/* Initialise the idle task for this CPU */
280 	mmgrab(&init_mm);
281 	current->active_mm = &init_mm;
282 	BUG_ON(current->mm);
283 	enter_lazy_tlb(&init_mm, current);
284 
285 	init_IRQ();   /* make sure no IRQs are enabled or pending */
286 	start_cpu_itimer();
287 }
288 
289 
290 /*
291  * Slaves start using C here. Indirectly called from smp_slave_stext.
292  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
293  */
294 void __init smp_callin(unsigned long pdce_proc)
295 {
296 	int slave_id = cpu_now_booting;
297 
298 #ifdef CONFIG_64BIT
299 	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
300 			| PAGE0->mem_pdc) != pdce_proc);
301 #endif
302 
303 	smp_cpu_init(slave_id);
304 	preempt_disable();
305 
306 	flush_cache_all_local(); /* start with known state */
307 	flush_tlb_all_local(NULL);
308 
309 	local_irq_enable();  /* Interrupts have been off until now */
310 
311 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
312 
313 	/* NOTREACHED */
314 	panic("smp_callin() AAAAaaaaahhhh....\n");
315 }
316 
317 /*
318  * Bring one cpu online.
319  */
320 int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
321 {
322 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
323 	long timeout;
324 
325 	task_thread_info(idle)->cpu = cpuid;
326 
327 	/* Let _start know what logical CPU we're booting
328 	** (offset into init_tasks[],cpu_data[])
329 	*/
330 	cpu_now_booting = cpuid;
331 
332 	/*
333 	** boot strap code needs to know the task address since
334 	** it also contains the process stack.
335 	*/
336 	smp_init_current_idle_task = idle ;
337 	mb();
338 
339 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
340 
341 	/*
342 	** This gets PDC to release the CPU from a very tight loop.
343 	**
344 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
345 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
346 	** is executed after receiving the rendezvous signal (an interrupt to
347 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
348 	** contents of memory are valid."
349 	*/
350 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
351 	mb();
352 
353 	/*
354 	 * OK, wait a bit for that CPU to finish staggering about.
355 	 * Slave will set a bit when it reaches smp_cpu_init().
356 	 * Once the "monarch CPU" sees the bit change, it can move on.
357 	 */
358 	for (timeout = 0; timeout < 10000; timeout++) {
359 		if(cpu_online(cpuid)) {
360 			/* Which implies Slave has started up */
361 			cpu_now_booting = 0;
362 			smp_init_current_idle_task = NULL;
363 			goto alive ;
364 		}
365 		udelay(100);
366 		barrier();
367 	}
368 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
369 	return -1;
370 
371 alive:
372 	/* Remember the Slave data */
373 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
374 		cpuid, timeout * 100);
375 	return 0;
376 }
377 
378 void __init smp_prepare_boot_cpu(void)
379 {
380 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
381 
382 	/* Setup BSP mappings */
383 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
384 
385 	set_cpu_online(bootstrap_processor, true);
386 	set_cpu_present(bootstrap_processor, true);
387 }
388 
389 
390 
391 /*
392 ** inventory.c:do_inventory() hasn't yet been run and thus we
393 ** don't 'discover' the additional CPUs until later.
394 */
395 void __init smp_prepare_cpus(unsigned int max_cpus)
396 {
397 	int cpu;
398 
399 	for_each_possible_cpu(cpu)
400 		spin_lock_init(&per_cpu(ipi_lock, cpu));
401 
402 	init_cpu_present(cpumask_of(0));
403 
404 	parisc_max_cpus = max_cpus;
405 	if (!max_cpus)
406 		printk(KERN_INFO "SMP mode deactivated.\n");
407 }
408 
409 
410 void smp_cpus_done(unsigned int cpu_max)
411 {
412 	return;
413 }
414 
415 
416 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
417 {
418 	if (cpu != 0 && cpu < parisc_max_cpus && smp_boot_one_cpu(cpu, tidle))
419 		return -ENOSYS;
420 
421 	return cpu_online(cpu) ? 0 : -ENOSYS;
422 }
423 
424 #ifdef CONFIG_PROC_FS
425 int setup_profiling_timer(unsigned int multiplier)
426 {
427 	return -EINVAL;
428 }
429 #endif
430