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