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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/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 

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