xref: /openbmc/linux/arch/parisc/kernel/smp.c (revision 56c6eed1) 
1 /*
2 ** SMP Support
3 **
4 ** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
5 ** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
6 ** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
7 **
8 ** Lots of stuff stolen from arch/alpha/kernel/smp.c
9 ** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
10 **
11 ** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
12 ** -grant (1/12/2001)
13 **
14 **	This program is free software; you can redistribute it and/or modify
15 **	it under the terms of the GNU General Public License as published by
16 **      the Free Software Foundation; either version 2 of the License, or
17 **      (at your option) any later version.
18 */
19 #include <linux/types.h>
20 #include <linux/spinlock.h>
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/sched/mm.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/smp.h>
28 #include <linux/kernel_stat.h>
29 #include <linux/mm.h>
30 #include <linux/err.h>
31 #include <linux/delay.h>
32 #include <linux/bitops.h>
33 #include <linux/ftrace.h>
34 #include <linux/cpu.h>
35 
36 #include <linux/atomic.h>
37 #include <asm/current.h>
38 #include <asm/delay.h>
39 #include <asm/tlbflush.h>
40 
41 #include <asm/io.h>
42 #include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
43 #include <asm/mmu_context.h>
44 #include <asm/page.h>
45 #include <asm/pgtable.h>
46 #include <asm/pgalloc.h>
47 #include <asm/processor.h>
48 #include <asm/ptrace.h>
49 #include <asm/unistd.h>
50 #include <asm/cacheflush.h>
51 
52 #undef DEBUG_SMP
53 #ifdef DEBUG_SMP
54 static int smp_debug_lvl = 0;
55 #define smp_debug(lvl, printargs...)		\
56 		if (lvl >= smp_debug_lvl)	\
57 			printk(printargs);
58 #else
59 #define smp_debug(lvl, ...)	do { } while(0)
60 #endif /* DEBUG_SMP */
61 
62 volatile struct task_struct *smp_init_current_idle_task;
63 
64 /* track which CPU is booting */
65 static volatile int cpu_now_booting;
66 
67 static int parisc_max_cpus = 1;
68 
69 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
70 
71 enum ipi_message_type {
72 	IPI_NOP=0,
73 	IPI_RESCHEDULE=1,
74 	IPI_CALL_FUNC,
75 	IPI_CPU_START,
76 	IPI_CPU_STOP,
77 	IPI_CPU_TEST
78 };
79 
80 
81 /********** SMP inter processor interrupt and communication routines */
82 
83 #undef PER_CPU_IRQ_REGION
84 #ifdef PER_CPU_IRQ_REGION
85 /* XXX REVISIT Ignore for now.
86 **    *May* need this "hook" to register IPI handler
87 **    once we have perCPU ExtIntr switch tables.
88 */
89 static void
90 ipi_init(int cpuid)
91 {
92 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
93 
94 	if(cpu_online(cpuid) )
95 	{
96 		switch_to_idle_task(current);
97 	}
98 
99 	return;
100 }
101 #endif
102 
103 
104 /*
105 ** Yoink this CPU from the runnable list...
106 **
107 */
108 static void
109 halt_processor(void)
110 {
111 	/* REVISIT : redirect I/O Interrupts to another CPU? */
112 	/* REVISIT : does PM *know* this CPU isn't available? */
113 	set_cpu_online(smp_processor_id(), false);
114 	local_irq_disable();
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 
175 			default:
176 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
177 					this_cpu, which);
178 				return IRQ_NONE;
179 			} /* Switch */
180 		/* let in any pending interrupts */
181 		local_irq_enable();
182 		local_irq_disable();
183 		} /* while (ops) */
184 	}
185 	return IRQ_HANDLED;
186 }
187 
188 
189 static inline void
190 ipi_send(int cpu, enum ipi_message_type op)
191 {
192 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
193 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
194 	unsigned long flags;
195 
196 	spin_lock_irqsave(lock, flags);
197 	p->pending_ipi |= 1 << op;
198 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
199 	spin_unlock_irqrestore(lock, flags);
200 }
201 
202 static void
203 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
204 {
205 	int cpu;
206 
207 	for_each_cpu(cpu, mask)
208 		ipi_send(cpu, op);
209 }
210 
211 static inline void
212 send_IPI_single(int dest_cpu, enum ipi_message_type op)
213 {
214 	BUG_ON(dest_cpu == NO_PROC_ID);
215 
216 	ipi_send(dest_cpu, op);
217 }
218 
219 static inline void
220 send_IPI_allbutself(enum ipi_message_type op)
221 {
222 	int i;
223 
224 	for_each_online_cpu(i) {
225 		if (i != smp_processor_id())
226 			send_IPI_single(i, op);
227 	}
228 }
229 
230 
231 inline void
232 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
233 
234 void
235 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
236 
237 void
238 smp_send_all_nop(void)
239 {
240 	send_IPI_allbutself(IPI_NOP);
241 }
242 
243 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
244 {
245 	send_IPI_mask(mask, IPI_CALL_FUNC);
246 }
247 
248 void arch_send_call_function_single_ipi(int cpu)
249 {
250 	send_IPI_single(cpu, IPI_CALL_FUNC);
251 }
252 
253 /*
254  * Called by secondaries to update state and initialize CPU registers.
255  */
256 static void __init
257 smp_cpu_init(int cpunum)
258 {
259 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
260 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
261 
262 	/* Set modes and Enable floating point coprocessor */
263 	init_per_cpu(cpunum);
264 
265 	disable_sr_hashing();
266 
267 	mb();
268 
269 	/* Well, support 2.4 linux scheme as well. */
270 	if (cpu_online(cpunum))	{
271 		extern void machine_halt(void); /* arch/parisc.../process.c */
272 
273 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
274 		machine_halt();
275 	}
276 
277 	notify_cpu_starting(cpunum);
278 
279 	set_cpu_online(cpunum, true);
280 
281 	/* Initialise the idle task for this CPU */
282 	mmgrab(&init_mm);
283 	current->active_mm = &init_mm;
284 	BUG_ON(current->mm);
285 	enter_lazy_tlb(&init_mm, current);
286 
287 	init_IRQ();   /* make sure no IRQs are enabled or pending */
288 	start_cpu_itimer();
289 }
290 
291 
292 /*
293  * Slaves start using C here. Indirectly called from smp_slave_stext.
294  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
295  */
296 void __init smp_callin(unsigned long pdce_proc)
297 {
298 	int slave_id = cpu_now_booting;
299 
300 #ifdef CONFIG_64BIT
301 	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
302 			| PAGE0->mem_pdc) != pdce_proc);
303 #endif
304 
305 	smp_cpu_init(slave_id);
306 	preempt_disable();
307 
308 	flush_cache_all_local(); /* start with known state */
309 	flush_tlb_all_local(NULL);
310 
311 	local_irq_enable();  /* Interrupts have been off until now */
312 
313 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
314 
315 	/* NOTREACHED */
316 	panic("smp_callin() AAAAaaaaahhhh....\n");
317 }
318 
319 /*
320  * Bring one cpu online.
321  */
322 int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
323 {
324 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
325 	long timeout;
326 
327 	task_thread_info(idle)->cpu = cpuid;
328 
329 	/* Let _start know what logical CPU we're booting
330 	** (offset into init_tasks[],cpu_data[])
331 	*/
332 	cpu_now_booting = cpuid;
333 
334 	/*
335 	** boot strap code needs to know the task address since
336 	** it also contains the process stack.
337 	*/
338 	smp_init_current_idle_task = idle ;
339 	mb();
340 
341 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
342 
343 	/*
344 	** This gets PDC to release the CPU from a very tight loop.
345 	**
346 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
347 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
348 	** is executed after receiving the rendezvous signal (an interrupt to
349 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
350 	** contents of memory are valid."
351 	*/
352 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
353 	mb();
354 
355 	/*
356 	 * OK, wait a bit for that CPU to finish staggering about.
357 	 * Slave will set a bit when it reaches smp_cpu_init().
358 	 * Once the "monarch CPU" sees the bit change, it can move on.
359 	 */
360 	for (timeout = 0; timeout < 10000; timeout++) {
361 		if(cpu_online(cpuid)) {
362 			/* Which implies Slave has started up */
363 			cpu_now_booting = 0;
364 			smp_init_current_idle_task = NULL;
365 			goto alive ;
366 		}
367 		udelay(100);
368 		barrier();
369 	}
370 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
371 	return -1;
372 
373 alive:
374 	/* Remember the Slave data */
375 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
376 		cpuid, timeout * 100);
377 	return 0;
378 }
379 
380 void __init smp_prepare_boot_cpu(void)
381 {
382 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
383 
384 	/* Setup BSP mappings */
385 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
386 
387 	set_cpu_online(bootstrap_processor, true);
388 	set_cpu_present(bootstrap_processor, true);
389 }
390 
391 
392 
393 /*
394 ** inventory.c:do_inventory() hasn't yet been run and thus we
395 ** don't 'discover' the additional CPUs until later.
396 */
397 void __init smp_prepare_cpus(unsigned int max_cpus)
398 {
399 	int cpu;
400 
401 	for_each_possible_cpu(cpu)
402 		spin_lock_init(&per_cpu(ipi_lock, cpu));
403 
404 	init_cpu_present(cpumask_of(0));
405 
406 	parisc_max_cpus = max_cpus;
407 	if (!max_cpus)
408 		printk(KERN_INFO "SMP mode deactivated.\n");
409 }
410 
411 
412 void smp_cpus_done(unsigned int cpu_max)
413 {
414 	return;
415 }
416 
417 
418 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
419 {
420 	if (cpu != 0 && cpu < parisc_max_cpus && smp_boot_one_cpu(cpu, tidle))
421 		return -ENOSYS;
422 
423 	return cpu_online(cpu) ? 0 : -ENOSYS;
424 }
425 
426 #ifdef CONFIG_PROC_FS
427 int setup_profiling_timer(unsigned int multiplier)
428 {
429 	return -EINVAL;
430 }
431 #endif
432