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
  54static 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
  62volatile struct task_struct *smp_init_current_idle_task;
  63
  64/* track which CPU is booting */
  65static volatile int cpu_now_booting;
  66
  67static int parisc_max_cpus = 1;
  68
  69static DEFINE_PER_CPU(spinlock_t, ipi_lock);
  70
  71enum 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*/
  89static void
  90ipi_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*/
 108static void
 109halt_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
 120irqreturn_t __irq_entry
 121ipi_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
 188static inline void
 189ipi_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
 201static void
 202send_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
 210static inline void
 211send_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
 218static inline void
 219send_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
 230inline void 
 231smp_send_stop(void)     { send_IPI_allbutself(IPI_CPU_STOP); }
 232
 233void 
 234smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
 235
 236void
 237smp_send_all_nop(void)
 238{
 239        send_IPI_allbutself(IPI_NOP);
 240}
 241
 242void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 243{
 244        send_IPI_mask(mask, IPI_CALL_FUNC);
 245}
 246
 247void 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 */
 255static void __init
 256smp_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 */
 295void __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 */
 321int 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
 372alive:
 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
 379void __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*/
 396void __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
 411void smp_cpus_done(unsigned int cpu_max)
 412{
 413        return;
 414}
 415
 416
 417int __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
 426int setup_profiling_timer(unsigned int multiplier)
 427{
 428        return -EINVAL;
 429}
 430#endif
 431