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/mm.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 <linux/irqdomain.h>
  26 #include <linux/export.h>
  27
  28 #include <asm/processor.h>
  29 #include <asm/setup.h>
  30 #include <asm/mach_desc.h>
  31
  32 #ifndef CONFIG_ARC_HAS_LLSC
  33 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  34 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  35
  36 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock);
  37 EXPORT_SYMBOL_GPL(smp_bitops_lock);
  38 #endif
  39
  40 struct plat_smp_ops  __weak plat_smp_ops;
  41
  42 /* XXX: per cpu ? Only needed once in early seconday boot */
  43 struct task_struct *secondary_idle_tsk;
  44
  45 /* Called from start_kernel */
  46 void __init smp_prepare_boot_cpu(void)
  47 {
  48 }
  49
  50 /*
  51  * Called from setup_arch() before calling setup_processor()
  52  *
  53  * - Initialise the CPU possible map early - this describes the CPUs
  54  *   which may be present or become present in the system.
  55  * - Call early smp init hook. This can initialize a specific multi-core
  56  *   IP which is say common to several platforms (hence not part of
  57  *   platform specific int_early() hook)
  58  */
  59 void __init smp_init_cpus(void)
  60 {
  61         unsigned int i;
  62
  63         for (i = 0; i < NR_CPUS; i++)
  64                 set_cpu_possible(i, true);
  65
  66         if (plat_smp_ops.init_early_smp)
  67                 plat_smp_ops.init_early_smp();
  68 }
  69
  70 /* called from init ( ) =>  process 1 */
  71 void __init smp_prepare_cpus(unsigned int max_cpus)
  72 {
  73         int i;
  74
  75         /*
  76          * if platform didn't set the present map already, do it now
  77          * boot cpu is set to present already by init/main.c
  78          */
  79         if (num_present_cpus() <= 1) {
  80                 for (i = 0; i < max_cpus; i++)
  81                         set_cpu_present(i, true);
  82         }
  83 }
  84
  85 void __init smp_cpus_done(unsigned int max_cpus)
  86 {
  87
  88 }
  89
  90 /*
  91  * Default smp boot helper for Run-on-reset case where all cores start off
  92  * together. Non-masters need to wait for Master to start running.
  93  * This is implemented using a flag in memory, which Non-masters spin-wait on.
  94  * Master sets it to cpu-id of core to "ungate" it.
  95  */
  96 static volatile int wake_flag;
  97
  98 #ifdef CONFIG_ISA_ARCOMPACT
  99
 100 #define __boot_read(f)          f
 101 #define __boot_write(f, v)      f = v
 102
 103 #else
 104
 105 #define __boot_read(f)          arc_read_uncached_32(&f)
 106 #define __boot_write(f, v)      arc_write_uncached_32(&f, v)
 107
 108 #endif
 109
 110 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
 111 {
 112         BUG_ON(cpu == 0);
 113
 114         __boot_write(wake_flag, cpu);
 115 }
 116
 117 void arc_platform_smp_wait_to_boot(int cpu)
 118 {
 119         /* for halt-on-reset, we've waited already */
 120         if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
 121                 return;
 122
 123         while (__boot_read(wake_flag) != cpu)
 124                 ;
 125
 126         __boot_write(wake_flag, 0);
 127 }
 128
 129 const char *arc_platform_smp_cpuinfo(void)
 130 {
 131         return plat_smp_ops.info ? : "";
 132 }
 133
 134 /*
 135  * The very first "C" code executed by secondary
 136  * Called from asm stub in head.S
 137  * "current"/R25 already setup by low level boot code
 138  */
 139 void start_kernel_secondary(void)
 140 {
 141         struct mm_struct *mm = &init_mm;
 142         unsigned int cpu = smp_processor_id();
 143
 144         /* MMU, Caches, Vector Table, Interrupts etc */
 145         setup_processor();
 146
 147         mmget(mm);
 148         mmgrab(mm);
 149         current->active_mm = mm;
 150         cpumask_set_cpu(cpu, mm_cpumask(mm));
 151
 152         /* Some SMP H/w setup - for each cpu */
 153         if (plat_smp_ops.init_per_cpu)
 154                 plat_smp_ops.init_per_cpu(cpu);
 155
 156         if (machine_desc->init_per_cpu)
 157                 machine_desc->init_per_cpu(cpu);
 158
 159         notify_cpu_starting(cpu);
 160         set_cpu_online(cpu, true);
 161
 162         pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
 163
 164         local_irq_enable();
 165         preempt_disable();
 166         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 167 }
 168
 169 /*
 170  * Called from kernel_init( ) -> smp_init( ) - for each CPU
 171  *
 172  * At this point, Secondary Processor  is "HALT"ed:
 173  *  -It booted, but was halted in head.S
 174  *  -It was configured to halt-on-reset
 175  *  So need to wake it up.
 176  *
 177  * Essential requirements being where to run from (PC) and stack (SP)
 178 */
 179 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 180 {
 181         unsigned long wait_till;
 182
 183         secondary_idle_tsk = idle;
 184
 185         pr_info("Idle Task [%d] %p", cpu, idle);
 186         pr_info("Trying to bring up CPU%u ...\n", cpu);
 187
 188         if (plat_smp_ops.cpu_kick)
 189                 plat_smp_ops.cpu_kick(cpu,
 190                                 (unsigned long)first_lines_of_secondary);
 191         else
 192                 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
 193
 194         /* wait for 1 sec after kicking the secondary */
 195         wait_till = jiffies + HZ;
 196         while (time_before(jiffies, wait_till)) {
 197                 if (cpu_online(cpu))
 198                         break;
 199         }
 200
 201         if (!cpu_online(cpu)) {
 202                 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
 203                 return -1;
 204         }
 205
 206         secondary_idle_tsk = NULL;
 207
 208         return 0;
 209 }
 210
 211 /*
 212  * not supported here
 213  */
 214 int setup_profiling_timer(unsigned int multiplier)
 215 {
 216         return -EINVAL;
 217 }
 218
 219 /*****************************************************************************/
 220 /*              Inter Processor Interrupt Handling                           */
 221 /*****************************************************************************/
 222
 223 enum ipi_msg_type {
 224         IPI_EMPTY = 0,
 225         IPI_RESCHEDULE = 1,
 226         IPI_CALL_FUNC,
 227         IPI_CPU_STOP,
 228 };
 229
 230 /*
 231  * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
 232  * figure out what msg was sent. For those which don't (ARC has dedicated IPI
 233  * IRQ), the msg-type needs to be conveyed via per-cpu data
 234  */
 235
 236 static DEFINE_PER_CPU(unsigned long, ipi_data);
 237
 238 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
 239 {
 240         unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
 241         unsigned long old, new;
 242         unsigned long flags;
 243
 244         pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
 245
 246         local_irq_save(flags);
 247
 248         /*
 249          * Atomically write new msg bit (in case others are writing too),
 250          * and read back old value
 251          */
 252         do {
 253                 new = old = READ_ONCE(*ipi_data_ptr);
 254                 new |= 1U << msg;
 255         } while (cmpxchg(ipi_data_ptr, old, new) != old);
 256
 257         /*
 258          * Call the platform specific IPI kick function, but avoid if possible:
 259          * Only do so if there's no pending msg from other concurrent sender(s).
 260          * Otherwise, recevier will see this msg as well when it takes the
 261          * IPI corresponding to that msg. This is true, even if it is already in
 262          * IPI handler, because !@old means it has not yet dequeued the msg(s)
 263          * so @new msg can be a free-loader
 264          */
 265         if (plat_smp_ops.ipi_send && !old)
 266                 plat_smp_ops.ipi_send(cpu);
 267
 268         local_irq_restore(flags);
 269 }
 270
 271 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 272 {
 273         unsigned int cpu;
 274
 275         for_each_cpu(cpu, callmap)
 276                 ipi_send_msg_one(cpu, msg);
 277 }
 278
 279 void smp_send_reschedule(int cpu)
 280 {
 281         ipi_send_msg_one(cpu, IPI_RESCHEDULE);
 282 }
 283
 284 void smp_send_stop(void)
 285 {
 286         struct cpumask targets;
 287         cpumask_copy(&targets, cpu_online_mask);
 288         cpumask_clear_cpu(smp_processor_id(), &targets);
 289         ipi_send_msg(&targets, IPI_CPU_STOP);
 290 }
 291
 292 void arch_send_call_function_single_ipi(int cpu)
 293 {
 294         ipi_send_msg_one(cpu, IPI_CALL_FUNC);
 295 }
 296
 297 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 298 {
 299         ipi_send_msg(mask, IPI_CALL_FUNC);
 300 }
 301
 302 /*
 303  * ipi_cpu_stop - handle IPI from smp_send_stop()
 304  */
 305 static void ipi_cpu_stop(void)
 306 {
 307         machine_halt();
 308 }
 309
 310 static inline int __do_IPI(unsigned long msg)
 311 {
 312         int rc = 0;
 313
 314         switch (msg) {
 315         case IPI_RESCHEDULE:
 316                 scheduler_ipi();
 317                 break;
 318
 319         case IPI_CALL_FUNC:
 320                 generic_smp_call_function_interrupt();
 321                 break;
 322
 323         case IPI_CPU_STOP:
 324                 ipi_cpu_stop();
 325                 break;
 326
 327         default:
 328                 rc = 1;
 329         }
 330
 331         return rc;
 332 }
 333
 334 /*
 335  * arch-common ISR to handle for inter-processor interrupts
 336  * Has hooks for platform specific IPI
 337  */
 338 irqreturn_t do_IPI(int irq, void *dev_id)
 339 {
 340         unsigned long pending;
 341         unsigned long __maybe_unused copy;
 342
 343         pr_debug("IPI [%ld] received on cpu %d\n",
 344                  *this_cpu_ptr(&ipi_data), smp_processor_id());
 345
 346         if (plat_smp_ops.ipi_clear)
 347                 plat_smp_ops.ipi_clear(irq);
 348
 349         /*
 350          * "dequeue" the msg corresponding to this IPI (and possibly other
 351          * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
 352          */
 353         copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
 354
 355         do {
 356                 unsigned long msg = __ffs(pending);
 357                 int rc;
 358
 359                 rc = __do_IPI(msg);
 360                 if (rc)
 361                         pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
 362                 pending &= ~(1U << msg);
 363         } while (pending);
 364
 365         return IRQ_HANDLED;
 366 }
 367
 368 /*
 369  * API called by platform code to hookup arch-common ISR to their IPI IRQ
 370  *
 371  * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
 372  * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
 373  * request_percpu_irq() below will fail
 374  */
 375 static DEFINE_PER_CPU(int, ipi_dev);
 376
 377 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq)
 378 {
 379         int *dev = per_cpu_ptr(&ipi_dev, cpu);
 380         unsigned int virq = irq_find_mapping(NULL, hwirq);
 381
 382         if (!virq)
 383                 panic("Cannot find virq for root domain and hwirq=%lu", hwirq);
 384
 385         /* Boot cpu calls request, all call enable */
 386         if (!cpu) {
 387                 int rc;
 388
 389                 rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev);
 390                 if (rc)
 391                         panic("Percpu IRQ request failed for %u\n", virq);
 392         }
 393
 394         enable_percpu_irq(virq, 0);
 395
 396         return 0;
 397 }