xref: /openbmc/linux/arch/parisc/kernel/smp.c (revision 6d99a79c) 
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 				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 
174 			default:
175 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
176 					this_cpu, which);
177 				return IRQ_NONE;
178 			} /* Switch */
179 		/* let in any pending interrupts */
180 		local_irq_enable();
181 		local_irq_disable();
182 		} /* while (ops) */
183 	}
184 	return IRQ_HANDLED;
185 }
186 
187 
188 static inline void
189 ipi_send(int cpu, enum ipi_message_type op)
190 {
191 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
192 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
193 	unsigned long flags;
194 
195 	spin_lock_irqsave(lock, flags);
196 	p->pending_ipi |= 1 << op;
197 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
198 	spin_unlock_irqrestore(lock, flags);
199 }
200 
201 static void
202 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
203 {
204 	int cpu;
205 
206 	for_each_cpu(cpu, mask)
207 		ipi_send(cpu, op);
208 }
209 
210 static inline void
211 send_IPI_single(int dest_cpu, enum ipi_message_type op)
212 {
213 	BUG_ON(dest_cpu == NO_PROC_ID);
214 
215 	ipi_send(dest_cpu, op);
216 }
217 
218 static inline void
219 send_IPI_allbutself(enum ipi_message_type op)
220 {
221 	int i;
222 
223 	for_each_online_cpu(i) {
224 		if (i != smp_processor_id())
225 			send_IPI_single(i, op);
226 	}
227 }
228 
229 
230 inline void
231 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
232 
233 void
234 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
235 
236 void
237 smp_send_all_nop(void)
238 {
239 	send_IPI_allbutself(IPI_NOP);
240 }
241 
242 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
243 {
244 	send_IPI_mask(mask, IPI_CALL_FUNC);
245 }
246 
247 void arch_send_call_function_single_ipi(int cpu)
248 {
249 	send_IPI_single(cpu, IPI_CALL_FUNC);
250 }
251 
252 /*
253  * Called by secondaries to update state and initialize CPU registers.
254  */
255 static void __init
256 smp_cpu_init(int cpunum)
257 {
258 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
259 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
260 
261 	/* Set modes and Enable floating point coprocessor */
262 	init_per_cpu(cpunum);
263 
264 	disable_sr_hashing();
265 
266 	mb();
267 
268 	/* Well, support 2.4 linux scheme as well. */
269 	if (cpu_online(cpunum))	{
270 		extern void machine_halt(void); /* arch/parisc.../process.c */
271 
272 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
273 		machine_halt();
274 	}
275 
276 	notify_cpu_starting(cpunum);
277 
278 	set_cpu_online(cpunum, true);
279 
280 	/* Initialise the idle task for this CPU */
281 	mmgrab(&init_mm);
282 	current->active_mm = &init_mm;
283 	BUG_ON(current->mm);
284 	enter_lazy_tlb(&init_mm, current);
285 
286 	init_IRQ();   /* make sure no IRQs are enabled or pending */
287 	start_cpu_itimer();
288 }
289 
290 
291 /*
292  * Slaves start using C here. Indirectly called from smp_slave_stext.
293  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
294  */
295 void __init smp_callin(unsigned long pdce_proc)
296 {
297 	int slave_id = cpu_now_booting;
298 
299 #ifdef CONFIG_64BIT
300 	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
301 			| PAGE0->mem_pdc) != pdce_proc);
302 #endif
303 
304 	smp_cpu_init(slave_id);
305 	preempt_disable();
306 
307 	flush_cache_all_local(); /* start with known state */
308 	flush_tlb_all_local(NULL);
309 
310 	local_irq_enable();  /* Interrupts have been off until now */
311 
312 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
313 
314 	/* NOTREACHED */
315 	panic("smp_callin() AAAAaaaaahhhh....\n");
316 }
317 
318 /*
319  * Bring one cpu online.
320  */
321 int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
322 {
323 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
324 	long timeout;
325 
326 	task_thread_info(idle)->cpu = cpuid;
327 
328 	/* Let _start know what logical CPU we're booting
329 	** (offset into init_tasks[],cpu_data[])
330 	*/
331 	cpu_now_booting = cpuid;
332 
333 	/*
334 	** boot strap code needs to know the task address since
335 	** it also contains the process stack.
336 	*/
337 	smp_init_current_idle_task = idle ;
338 	mb();
339 
340 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
341 
342 	/*
343 	** This gets PDC to release the CPU from a very tight loop.
344 	**
345 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
346 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
347 	** is executed after receiving the rendezvous signal (an interrupt to
348 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
349 	** contents of memory are valid."
350 	*/
351 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
352 	mb();
353 
354 	/*
355 	 * OK, wait a bit for that CPU to finish staggering about.
356 	 * Slave will set a bit when it reaches smp_cpu_init().
357 	 * Once the "monarch CPU" sees the bit change, it can move on.
358 	 */
359 	for (timeout = 0; timeout < 10000; timeout++) {
360 		if(cpu_online(cpuid)) {
361 			/* Which implies Slave has started up */
362 			cpu_now_booting = 0;
363 			smp_init_current_idle_task = NULL;
364 			goto alive ;
365 		}
366 		udelay(100);
367 		barrier();
368 	}
369 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
370 	return -1;
371 
372 alive:
373 	/* Remember the Slave data */
374 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
375 		cpuid, timeout * 100);
376 	return 0;
377 }
378 
379 void __init smp_prepare_boot_cpu(void)
380 {
381 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
382 
383 	/* Setup BSP mappings */
384 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
385 
386 	set_cpu_online(bootstrap_processor, true);
387 	set_cpu_present(bootstrap_processor, true);
388 }
389 
390 
391 
392 /*
393 ** inventory.c:do_inventory() hasn't yet been run and thus we
394 ** don't 'discover' the additional CPUs until later.
395 */
396 void __init smp_prepare_cpus(unsigned int max_cpus)
397 {
398 	int cpu;
399 
400 	for_each_possible_cpu(cpu)
401 		spin_lock_init(&per_cpu(ipi_lock, cpu));
402 
403 	init_cpu_present(cpumask_of(0));
404 
405 	parisc_max_cpus = max_cpus;
406 	if (!max_cpus)
407 		printk(KERN_INFO "SMP mode deactivated.\n");
408 }
409 
410 
411 void smp_cpus_done(unsigned int cpu_max)
412 {
413 	return;
414 }
415 
416 
417 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
418 {
419 	if (cpu != 0 && cpu < parisc_max_cpus && smp_boot_one_cpu(cpu, tidle))
420 		return -ENOSYS;
421 
422 	return cpu_online(cpu) ? 0 : -ENOSYS;
423 }
424 
425 #ifdef CONFIG_PROC_FS
426 int setup_profiling_timer(unsigned int multiplier)
427 {
428 	return -EINVAL;
429 }
430 #endif
431