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Linux/arch/parisc/kernel/smp.c

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  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.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 int init_per_cpu(int);  /* arch/parisc/kernel/processor.c */
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         (void) 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         atomic_inc(&init_mm.mm_count);
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(void)
297 {
298         int slave_id = cpu_now_booting;
299 
300         smp_cpu_init(slave_id);
301         preempt_disable();
302 
303         flush_cache_all_local(); /* start with known state */
304         flush_tlb_all_local(NULL);
305 
306         local_irq_enable();  /* Interrupts have been off until now */
307 
308         cpu_startup_entry(CPUHP_ONLINE);
309 
310         /* NOTREACHED */
311         panic("smp_callin() AAAAaaaaahhhh....\n");
312 }
313 
314 /*
315  * Bring one cpu online.
316  */
317 int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
318 {
319         const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
320         long timeout;
321 
322         task_thread_info(idle)->cpu = cpuid;
323 
324         /* Let _start know what logical CPU we're booting
325         ** (offset into init_tasks[],cpu_data[])
326         */
327         cpu_now_booting = cpuid;
328 
329         /* 
330         ** boot strap code needs to know the task address since
331         ** it also contains the process stack.
332         */
333         smp_init_current_idle_task = idle ;
334         mb();
335 
336         printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
337 
338         /*
339         ** This gets PDC to release the CPU from a very tight loop.
340         **
341         ** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
342         ** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which 
343         ** is executed after receiving the rendezvous signal (an interrupt to 
344         ** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the 
345         ** contents of memory are valid."
346         */
347         gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
348         mb();
349 
350         /* 
351          * OK, wait a bit for that CPU to finish staggering about. 
352          * Slave will set a bit when it reaches smp_cpu_init().
353          * Once the "monarch CPU" sees the bit change, it can move on.
354          */
355         for (timeout = 0; timeout < 10000; timeout++) {
356                 if(cpu_online(cpuid)) {
357                         /* Which implies Slave has started up */
358                         cpu_now_booting = 0;
359                         smp_init_current_idle_task = NULL;
360                         goto alive ;
361                 }
362                 udelay(100);
363                 barrier();
364         }
365         printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
366         return -1;
367 
368 alive:
369         /* Remember the Slave data */
370         smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
371                 cpuid, timeout * 100);
372         return 0;
373 }
374 
375 void __init smp_prepare_boot_cpu(void)
376 {
377         int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
378 
379         /* Setup BSP mappings */
380         printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
381 
382         set_cpu_online(bootstrap_processor, true);
383         set_cpu_present(bootstrap_processor, true);
384 }
385 
386 
387 
388 /*
389 ** inventory.c:do_inventory() hasn't yet been run and thus we
390 ** don't 'discover' the additional CPUs until later.
391 */
392 void __init smp_prepare_cpus(unsigned int max_cpus)
393 {
394         int cpu;
395 
396         for_each_possible_cpu(cpu)
397                 spin_lock_init(&per_cpu(ipi_lock, cpu));
398 
399         init_cpu_present(cpumask_of(0));
400 
401         parisc_max_cpus = max_cpus;
402         if (!max_cpus)
403                 printk(KERN_INFO "SMP mode deactivated.\n");
404 }
405 
406 
407 void smp_cpus_done(unsigned int cpu_max)
408 {
409         return;
410 }
411 
412 
413 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
414 {
415         if (cpu != 0 && cpu < parisc_max_cpus)
416                 smp_boot_one_cpu(cpu, tidle);
417 
418         return cpu_online(cpu) ? 0 : -ENOSYS;
419 }
420 
421 #ifdef CONFIG_PROC_FS
422 int __init
423 setup_profiling_timer(unsigned int multiplier)
424 {
425         return -EINVAL;
426 }
427 #endif
428 

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