arch/arc/kernel/smp.c

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * RajeshwarR: Dec 11, 2007
   9  *   -- Added support for Inter Processor Interrupts
  10  *
  11  * Vineetg: Nov 1st, 2007
  12  *    -- Initial Write (Borrowed heavily from ARM)
  13  */
  14
  15 #include <linux/spinlock.h>
  16 #include <linux/sched.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/profile.h>
  19 #include <linux/mm.h>
  20 #include <linux/cpu.h>
  21 #include <linux/irq.h>
  22 #include <linux/atomic.h>
  23 #include <linux/cpumask.h>
  24 #include <linux/reboot.h>
  25 #include <asm/processor.h>
  26 #include <asm/setup.h>
  27 #include <asm/mach_desc.h>
  28
  29 #ifndef CONFIG_ARC_HAS_LLSC
  30 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  31 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  32 #endif
  33
  34 struct plat_smp_ops  __weak plat_smp_ops;
  35
  36 /* XXX: per cpu ? Only needed once in early seconday boot */
  37 struct task_struct *secondary_idle_tsk;
  38
  39 /* Called from start_kernel */
  40 void __init smp_prepare_boot_cpu(void)
  41 {
  42 }
  43
  44 /*
  45  * Called from setup_arch() before calling setup_processor()
  46  *
  47  * - Initialise the CPU possible map early - this describes the CPUs
  48  *   which may be present or become present in the system.
  49  * - Call early smp init hook. This can initialize a specific multi-core
  50  *   IP which is say common to several platforms (hence not part of
  51  *   platform specific int_early() hook)
  52  */
  53 void __init smp_init_cpus(void)
  54 {
  55         unsigned int i;
  56
  57         for (i = 0; i < NR_CPUS; i++)
  58                 set_cpu_possible(i, true);
  59
  60         if (plat_smp_ops.init_early_smp)
  61                 plat_smp_ops.init_early_smp();
  62 }
  63
  64 /* called from init ( ) =>  process 1 */
  65 void __init smp_prepare_cpus(unsigned int max_cpus)
  66 {
  67         int i;
  68
  69         /*
  70          * Initialise the present map, which describes the set of CPUs
  71          * actually populated at the present time.
  72          */
  73         for (i = 0; i < max_cpus; i++)
  74                 set_cpu_present(i, true);
  75 }
  76
  77 void __init smp_cpus_done(unsigned int max_cpus)
  78 {
  79
  80 }
  81
  82 /*
  83  * Default smp boot helper for Run-on-reset case where all cores start off
  84  * together. Non-masters need to wait for Master to start running.
  85  * This is implemented using a flag in memory, which Non-masters spin-wait on.
  86  * Master sets it to cpu-id of core to "ungate" it.
  87  */
  88 static volatile int wake_flag;
  89
  90 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
  91 {
  92         BUG_ON(cpu == 0);
  93         wake_flag = cpu;
  94 }
  95
  96 void arc_platform_smp_wait_to_boot(int cpu)
  97 {
  98         while (wake_flag != cpu)
  99                 ;
 100
 101         wake_flag = 0;
 102         __asm__ __volatile__("j @first_lines_of_secondary       \n");
 103 }
 104
 105
 106 const char *arc_platform_smp_cpuinfo(void)
 107 {
 108         return plat_smp_ops.info ? : "";
 109 }
 110
 111 /*
 112  * The very first "C" code executed by secondary
 113  * Called from asm stub in head.S
 114  * "current"/R25 already setup by low level boot code
 115  */
 116 void start_kernel_secondary(void)
 117 {
 118         struct mm_struct *mm = &init_mm;
 119         unsigned int cpu = smp_processor_id();
 120
 121         /* MMU, Caches, Vector Table, Interrupts etc */
 122         setup_processor();
 123
 124         atomic_inc(&mm->mm_users);
 125         atomic_inc(&mm->mm_count);
 126         current->active_mm = mm;
 127         cpumask_set_cpu(cpu, mm_cpumask(mm));
 128
 129         notify_cpu_starting(cpu);
 130         set_cpu_online(cpu, true);
 131
 132         pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
 133
 134         /* Some SMP H/w setup - for each cpu */
 135         if (plat_smp_ops.init_irq_cpu)
 136                 plat_smp_ops.init_irq_cpu(cpu);
 137
 138         if (machine_desc->init_cpu_smp)
 139                 machine_desc->init_cpu_smp(cpu);
 140
 141         arc_local_timer_setup();
 142
 143         local_irq_enable();
 144         preempt_disable();
 145         cpu_startup_entry(CPUHP_ONLINE);
 146 }
 147
 148 /*
 149  * Called from kernel_init( ) -> smp_init( ) - for each CPU
 150  *
 151  * At this point, Secondary Processor  is "HALT"ed:
 152  *  -It booted, but was halted in head.S
 153  *  -It was configured to halt-on-reset
 154  *  So need to wake it up.
 155  *
 156  * Essential requirements being where to run from (PC) and stack (SP)
 157 */
 158 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 159 {
 160         unsigned long wait_till;
 161
 162         secondary_idle_tsk = idle;
 163
 164         pr_info("Idle Task [%d] %p", cpu, idle);
 165         pr_info("Trying to bring up CPU%u ...\n", cpu);
 166
 167         if (plat_smp_ops.cpu_kick)
 168                 plat_smp_ops.cpu_kick(cpu,
 169                                 (unsigned long)first_lines_of_secondary);
 170         else
 171                 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
 172
 173         /* wait for 1 sec after kicking the secondary */
 174         wait_till = jiffies + HZ;
 175         while (time_before(jiffies, wait_till)) {
 176                 if (cpu_online(cpu))
 177                         break;
 178         }
 179
 180         if (!cpu_online(cpu)) {
 181                 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
 182                 return -1;
 183         }
 184
 185         secondary_idle_tsk = NULL;
 186
 187         return 0;
 188 }
 189
 190 /*
 191  * not supported here
 192  */
 193 int setup_profiling_timer(unsigned int multiplier)
 194 {
 195         return -EINVAL;
 196 }
 197
 198 /*****************************************************************************/
 199 /*              Inter Processor Interrupt Handling                           */
 200 /*****************************************************************************/
 201
 202 enum ipi_msg_type {
 203         IPI_EMPTY = 0,
 204         IPI_RESCHEDULE = 1,
 205         IPI_CALL_FUNC,
 206         IPI_CPU_STOP,
 207 };
 208
 209 /*
 210  * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
 211  * figure out what msg was sent. For those which don't (ARC has dedicated IPI
 212  * IRQ), the msg-type needs to be conveyed via per-cpu data
 213  */
 214
 215 static DEFINE_PER_CPU(unsigned long, ipi_data);
 216
 217 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
 218 {
 219         unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
 220         unsigned long old, new;
 221         unsigned long flags;
 222
 223         pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
 224
 225         local_irq_save(flags);
 226
 227         /*
 228          * Atomically write new msg bit (in case others are writing too),
 229          * and read back old value
 230          */
 231         do {
 232                 new = old = ACCESS_ONCE(*ipi_data_ptr);
 233                 new |= 1U << msg;
 234         } while (cmpxchg(ipi_data_ptr, old, new) != old);
 235
 236         /*
 237          * Call the platform specific IPI kick function, but avoid if possible:
 238          * Only do so if there's no pending msg from other concurrent sender(s).
 239          * Otherwise, recevier will see this msg as well when it takes the
 240          * IPI corresponding to that msg. This is true, even if it is already in
 241          * IPI handler, because !@old means it has not yet dequeued the msg(s)
 242          * so @new msg can be a free-loader
 243          */
 244         if (plat_smp_ops.ipi_send && !old)
 245                 plat_smp_ops.ipi_send(cpu);
 246
 247         local_irq_restore(flags);
 248 }
 249
 250 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 251 {
 252         unsigned int cpu;
 253
 254         for_each_cpu(cpu, callmap)
 255                 ipi_send_msg_one(cpu, msg);
 256 }
 257
 258 void smp_send_reschedule(int cpu)
 259 {
 260         ipi_send_msg_one(cpu, IPI_RESCHEDULE);
 261 }
 262
 263 void smp_send_stop(void)
 264 {
 265         struct cpumask targets;
 266         cpumask_copy(&targets, cpu_online_mask);
 267         cpumask_clear_cpu(smp_processor_id(), &targets);
 268         ipi_send_msg(&targets, IPI_CPU_STOP);
 269 }
 270
 271 void arch_send_call_function_single_ipi(int cpu)
 272 {
 273         ipi_send_msg_one(cpu, IPI_CALL_FUNC);
 274 }
 275
 276 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 277 {
 278         ipi_send_msg(mask, IPI_CALL_FUNC);
 279 }
 280
 281 /*
 282  * ipi_cpu_stop - handle IPI from smp_send_stop()
 283  */
 284 static void ipi_cpu_stop(void)
 285 {
 286         machine_halt();
 287 }
 288
 289 static inline int __do_IPI(unsigned long msg)
 290 {
 291         int rc = 0;
 292
 293         switch (msg) {
 294         case IPI_RESCHEDULE:
 295                 scheduler_ipi();
 296                 break;
 297
 298         case IPI_CALL_FUNC:
 299                 generic_smp_call_function_interrupt();
 300                 break;
 301
 302         case IPI_CPU_STOP:
 303                 ipi_cpu_stop();
 304                 break;
 305
 306         default:
 307                 rc = 1;
 308         }
 309
 310         return rc;
 311 }
 312
 313 /*
 314  * arch-common ISR to handle for inter-processor interrupts
 315  * Has hooks for platform specific IPI
 316  */
 317 irqreturn_t do_IPI(int irq, void *dev_id)
 318 {
 319         unsigned long pending;
 320         unsigned long __maybe_unused copy;
 321
 322         pr_debug("IPI [%ld] received on cpu %d\n",
 323                  *this_cpu_ptr(&ipi_data), smp_processor_id());
 324
 325         if (plat_smp_ops.ipi_clear)
 326                 plat_smp_ops.ipi_clear(irq);
 327
 328         /*
 329          * "dequeue" the msg corresponding to this IPI (and possibly other
 330          * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
 331          */
 332         copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
 333
 334         do {
 335                 unsigned long msg = __ffs(pending);
 336                 int rc;
 337
 338                 rc = __do_IPI(msg);
 339 #ifdef CONFIG_ARC_IPI_DBG
 340                 /* IPI received but no valid @msg */
 341                 if (rc)
 342                         pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
 343 #endif
 344                 pending &= ~(1U << msg);
 345         } while (pending);
 346
 347         return IRQ_HANDLED;
 348 }
 349
 350 /*
 351  * API called by platform code to hookup arch-common ISR to their IPI IRQ
 352  */
 353 static DEFINE_PER_CPU(int, ipi_dev);
 354
 355 int smp_ipi_irq_setup(int cpu, int irq)
 356 {
 357         int *dev = per_cpu_ptr(&ipi_dev, cpu);
 358
 359         arc_request_percpu_irq(irq, cpu, do_IPI, "IPI Interrupt", dev);
 360
 361         return 0;
 362 }