arch/ppc/kernel/smp.c

   1 /*
   2  * Smp support for ppc.
   3  *
   4  * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
   5  * deal of code from the sparc and intel versions.
   6  *
   7  * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
   8  *
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/smp.h>
  16 #include <linux/smp_lock.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kernel_stat.h>
  19 #include <linux/delay.h>
  20 #include <linux/init.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/cache.h>
  23
  24 #include <asm/ptrace.h>
  25 #include <asm/atomic.h>
  26 #include <asm/irq.h>
  27 #include <asm/page.h>
  28 #include <asm/pgtable.h>
  29 #include <asm/io.h>
  30 #include <asm/prom.h>
  31 #include <asm/smp.h>
  32 #include <asm/residual.h>
  33 #include <asm/time.h>
  34 #include <asm/thread_info.h>
  35 #include <asm/tlbflush.h>
  36 #include <asm/xmon.h>
  37 #include <asm/machdep.h>
  38
  39 volatile int smp_commenced;
  40 int smp_tb_synchronized;
  41 struct cpuinfo_PPC cpu_data[NR_CPUS];
  42 atomic_t ipi_recv;
  43 atomic_t ipi_sent;
  44 cpumask_t cpu_online_map;
  45 cpumask_t cpu_possible_map;
  46 int smp_hw_index[NR_CPUS];
  47 struct thread_info *secondary_ti;
  48 static struct task_struct *idle_tasks[NR_CPUS];
  49
  50 EXPORT_SYMBOL(cpu_online_map);
  51 EXPORT_SYMBOL(cpu_possible_map);
  52
  53 /* SMP operations for this machine */
  54 struct smp_ops_t *smp_ops;
  55
  56 /* all cpu mappings are 1-1 -- Cort */
  57 volatile unsigned long cpu_callin_map[NR_CPUS];
  58
  59 int start_secondary(void *);
  60 void smp_call_function_interrupt(void);
  61 static int __smp_call_function(void (*func) (void *info), void *info,
  62                                int wait, int target);
  63
  64 /* Low level assembly function used to backup CPU 0 state */
  65 extern void __save_cpu_setup(void);
  66
  67 /* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
  68  *
  69  * Make sure this matches openpic_request_IPIs in open_pic.c, or what shows up
  70  * in /proc/interrupts will be wrong!!! --Troy */
  71 #define PPC_MSG_CALL_FUNCTION   0
  72 #define PPC_MSG_RESCHEDULE      1
  73 #define PPC_MSG_INVALIDATE_TLB  2
  74 #define PPC_MSG_XMON_BREAK      3
  75
  76 static inline void
  77 smp_message_pass(int target, int msg)
  78 {
  79         if (smp_ops) {
  80                 atomic_inc(&ipi_sent);
  81                 smp_ops->message_pass(target, msg);
  82         }
  83 }
  84
  85 /*
  86  * Common functions
  87  */
  88 void smp_message_recv(int msg, struct pt_regs *regs)
  89 {
  90         atomic_inc(&ipi_recv);
  91
  92         switch( msg ) {
  93         case PPC_MSG_CALL_FUNCTION:
  94                 smp_call_function_interrupt();
  95                 break;
  96         case PPC_MSG_RESCHEDULE:
  97                 set_need_resched();
  98                 break;
  99         case PPC_MSG_INVALIDATE_TLB:
 100                 _tlbia();
 101                 break;
 102 #ifdef CONFIG_XMON
 103         case PPC_MSG_XMON_BREAK:
 104                 xmon(regs);
 105                 break;
 106 #endif /* CONFIG_XMON */
 107         default:
 108                 printk("SMP %d: smp_message_recv(): unknown msg %d\n",
 109                        smp_processor_id(), msg);
 110                 break;
 111         }
 112 }
 113
 114 /*
 115  * 750's don't broadcast tlb invalidates so
 116  * we have to emulate that behavior.
 117  *   -- Cort
 118  */
 119 void smp_send_tlb_invalidate(int cpu)
 120 {
 121         if ( PVR_VER(mfspr(SPRN_PVR)) == 8 )
 122                 smp_message_pass(MSG_ALL_BUT_SELF, PPC_MSG_INVALIDATE_TLB);
 123 }
 124
 125 void smp_send_reschedule(int cpu)
 126 {
 127         /*
 128          * This is only used if `cpu' is running an idle task,
 129          * so it will reschedule itself anyway...
 130          *
 131          * This isn't the case anymore since the other CPU could be
 132          * sleeping and won't reschedule until the next interrupt (such
 133          * as the timer).
 134          *  -- Cort
 135          */
 136         /* This is only used if `cpu' is running an idle task,
 137            so it will reschedule itself anyway... */
 138         smp_message_pass(cpu, PPC_MSG_RESCHEDULE);
 139 }
 140
 141 #ifdef CONFIG_XMON
 142 void smp_send_xmon_break(int cpu)
 143 {
 144         smp_message_pass(cpu, PPC_MSG_XMON_BREAK);
 145 }
 146 #endif /* CONFIG_XMON */
 147
 148 static void stop_this_cpu(void *dummy)
 149 {
 150         local_irq_disable();
 151         while (1)
 152                 ;
 153 }
 154
 155 void smp_send_stop(void)
 156 {
 157         smp_call_function(stop_this_cpu, NULL, 1, 0);
 158 }
 159
 160 /*
 161  * Structure and data for smp_call_function(). This is designed to minimise
 162  * static memory requirements. It also looks cleaner.
 163  * Stolen from the i386 version.
 164  */
 165 static DEFINE_SPINLOCK(call_lock);
 166
 167 static struct call_data_struct {
 168         void (*func) (void *info);
 169         void *info;
 170         atomic_t started;
 171         atomic_t finished;
 172         int wait;
 173 } *call_data;
 174
 175 /*
 176  * this function sends a 'generic call function' IPI to all other CPUs
 177  * in the system.
 178  */
 179
 180 int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
 181                       int wait)
 182 /*
 183  * [SUMMARY] Run a function on all other CPUs.
 184  * <func> The function to run. This must be fast and non-blocking.
 185  * <info> An arbitrary pointer to pass to the function.
 186  * <nonatomic> currently unused.
 187  * <wait> If true, wait (atomically) until function has completed on other CPUs.
 188  * [RETURNS] 0 on success, else a negative status code. Does not return until
 189  * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 190  *
 191  * You must not call this function with disabled interrupts or from a
 192  * hardware interrupt handler or from a bottom half handler.
 193  */
 194 {
 195         /* FIXME: get cpu lock with hotplug cpus, or change this to
 196            bitmask. --RR */
 197         if (num_online_cpus() <= 1)
 198                 return 0;
 199         /* Can deadlock when called with interrupts disabled */
 200         WARN_ON(irqs_disabled());
 201         return __smp_call_function(func, info, wait, MSG_ALL_BUT_SELF);
 202 }
 203
 204 static int __smp_call_function(void (*func) (void *info), void *info,
 205                                int wait, int target)
 206 {
 207         struct call_data_struct data;
 208         int ret = -1;
 209         int timeout;
 210         int ncpus = 1;
 211
 212         if (target == MSG_ALL_BUT_SELF)
 213                 ncpus = num_online_cpus() - 1;
 214         else if (target == MSG_ALL)
 215                 ncpus = num_online_cpus();
 216
 217         data.func = func;
 218         data.info = info;
 219         atomic_set(&data.started, 0);
 220         data.wait = wait;
 221         if (wait)
 222                 atomic_set(&data.finished, 0);
 223
 224         spin_lock(&call_lock);
 225         call_data = &data;
 226         /* Send a message to all other CPUs and wait for them to respond */
 227         smp_message_pass(target, PPC_MSG_CALL_FUNCTION);
 228
 229         /* Wait for response */
 230         timeout = 1000000;
 231         while (atomic_read(&data.started) != ncpus) {
 232                 if (--timeout == 0) {
 233                         printk("smp_call_function on cpu %d: other cpus not responding (%d)\n",
 234                                smp_processor_id(), atomic_read(&data.started));
 235                         goto out;
 236                 }
 237                 barrier();
 238                 udelay(1);
 239         }
 240
 241         if (wait) {
 242                 timeout = 1000000;
 243                 while (atomic_read(&data.finished) != ncpus) {
 244                         if (--timeout == 0) {
 245                                 printk("smp_call_function on cpu %d: other cpus not finishing (%d/%d)\n",
 246                                        smp_processor_id(), atomic_read(&data.finished), atomic_read(&data.started));
 247                                 goto out;
 248                         }
 249                         barrier();
 250                         udelay(1);
 251                 }
 252         }
 253         ret = 0;
 254
 255  out:
 256         spin_unlock(&call_lock);
 257         return ret;
 258 }
 259
 260 void smp_call_function_interrupt(void)
 261 {
 262         void (*func) (void *info) = call_data->func;
 263         void *info = call_data->info;
 264         int wait = call_data->wait;
 265
 266         /*
 267          * Notify initiating CPU that I've grabbed the data and am
 268          * about to execute the function
 269          */
 270         atomic_inc(&call_data->started);
 271         /*
 272          * At this point the info structure may be out of scope unless wait==1
 273          */
 274         (*func)(info);
 275         if (wait)
 276                 atomic_inc(&call_data->finished);
 277 }
 278
 279 static void __devinit smp_store_cpu_info(int id)
 280 {
 281         struct cpuinfo_PPC *c = &cpu_data[id];
 282
 283         /* assume bogomips are same for everything */
 284         c->loops_per_jiffy = loops_per_jiffy;
 285         c->pvr = mfspr(SPRN_PVR);
 286 }
 287
 288 void __init smp_prepare_cpus(unsigned int max_cpus)
 289 {
 290         int num_cpus, i, cpu;
 291         struct task_struct *p;
 292
 293         /* Fixup boot cpu */
 294         smp_store_cpu_info(smp_processor_id());
 295         cpu_callin_map[smp_processor_id()] = 1;
 296
 297         if (smp_ops == NULL) {
 298                 printk("SMP not supported on this machine.\n");
 299                 return;
 300         }
 301
 302         /* Probe platform for CPUs: always linear. */
 303         num_cpus = smp_ops->probe();
 304
 305         if (num_cpus < 2)
 306                 smp_tb_synchronized = 1;
 307
 308         for (i = 0; i < num_cpus; ++i)
 309                 cpu_set(i, cpu_possible_map);
 310
 311         /* Backup CPU 0 state */
 312         __save_cpu_setup();
 313
 314         for_each_cpu(cpu) {
 315                 if (cpu == smp_processor_id())
 316                         continue;
 317                 /* create a process for the processor */
 318                 p = fork_idle(cpu);
 319                 if (IS_ERR(p))
 320                         panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
 321                 p->thread_info->cpu = cpu;
 322                 idle_tasks[cpu] = p;
 323         }
 324 }
 325
 326 void __devinit smp_prepare_boot_cpu(void)
 327 {
 328         cpu_set(smp_processor_id(), cpu_online_map);
 329         cpu_set(smp_processor_id(), cpu_possible_map);
 330 }
 331
 332 int __init setup_profiling_timer(unsigned int multiplier)
 333 {
 334         return 0;
 335 }
 336
 337 /* Processor coming up starts here */
 338 int __devinit start_secondary(void *unused)
 339 {
 340         int cpu;
 341
 342         atomic_inc(&init_mm.mm_count);
 343         current->active_mm = &init_mm;
 344
 345         cpu = smp_processor_id();
 346         smp_store_cpu_info(cpu);
 347         set_dec(tb_ticks_per_jiffy);
 348         preempt_disable();
 349         cpu_callin_map[cpu] = 1;
 350
 351         printk("CPU %d done callin...\n", cpu);
 352         smp_ops->setup_cpu(cpu);
 353         printk("CPU %d done setup...\n", cpu);
 354         smp_ops->take_timebase();
 355         printk("CPU %d done timebase take...\n", cpu);
 356
 357         spin_lock(&call_lock);
 358         cpu_set(cpu, cpu_online_map);
 359         spin_unlock(&call_lock);
 360
 361         local_irq_enable();
 362
 363         cpu_idle();
 364         return 0;
 365 }
 366
 367 int __cpu_up(unsigned int cpu)
 368 {
 369         char buf[32];
 370         int c;
 371
 372         secondary_ti = idle_tasks[cpu]->thread_info;
 373         mb();
 374
 375         /*
 376          * There was a cache flush loop here to flush the cache
 377          * to memory for the first 8MB of RAM.  The cache flush
 378          * has been pushed into the kick_cpu function for those
 379          * platforms that need it.
 380          */
 381
 382         /* wake up cpu */
 383         smp_ops->kick_cpu(cpu);
 384
 385         /*
 386          * wait to see if the cpu made a callin (is actually up).
 387          * use this value that I found through experimentation.
 388          * -- Cort
 389          */
 390         for (c = 1000; c && !cpu_callin_map[cpu]; c--)
 391                 udelay(100);
 392
 393         if (!cpu_callin_map[cpu]) {
 394                 sprintf(buf, "didn't find cpu %u", cpu);
 395                 if (ppc_md.progress) ppc_md.progress(buf, 0x360+cpu);
 396                 printk("Processor %u is stuck.\n", cpu);
 397                 return -ENOENT;
 398         }
 399
 400         sprintf(buf, "found cpu %u", cpu);
 401         if (ppc_md.progress) ppc_md.progress(buf, 0x350+cpu);
 402         printk("Processor %d found.\n", cpu);
 403
 404         smp_ops->give_timebase();
 405
 406         /* Wait until cpu puts itself in the online map */
 407         while (!cpu_online(cpu))
 408                 cpu_relax();
 409
 410         return 0;
 411 }
 412
 413 void smp_cpus_done(unsigned int max_cpus)
 414 {
 415         smp_ops->setup_cpu(0);
 416 }