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 #include <linux/of_fdt.h>
  28
  29 #include <asm/processor.h>
  30 #include <asm/setup.h>
  31 #include <asm/mach_desc.h>
  32
  33 #ifndef CONFIG_ARC_HAS_LLSC
  34 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  35 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  36
  37 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock);
  38 EXPORT_SYMBOL_GPL(smp_bitops_lock);
  39 #endif
  40
  41 struct plat_smp_ops  __weak plat_smp_ops;
  42
  43 /* XXX: per cpu ? Only needed once in early seconday boot */
  44 struct task_struct *secondary_idle_tsk;
  45
  46 /* Called from start_kernel */
  47 void __init smp_prepare_boot_cpu(void)
  48 {
  49 }
  50
  51 static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
  52 {
  53         unsigned long dt_root = of_get_flat_dt_root();
  54         const char *buf;
  55
  56         buf = of_get_flat_dt_prop(dt_root, name, NULL);
  57         if (!buf)
  58                 return -EINVAL;
  59
  60         if (cpulist_parse(buf, cpumask))
  61                 return -EINVAL;
  62
  63         return 0;
  64 }
  65
  66 /*
  67  * Read from DeviceTree and setup cpu possible mask. If there is no
  68  * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist.
  69  */
  70 static void __init arc_init_cpu_possible(void)
  71 {
  72         struct cpumask cpumask;
  73
  74         if (arc_get_cpu_map("possible-cpus", &cpumask)) {
  75                 pr_warn("Failed to get possible-cpus from dtb, pretending all %u cpus exist\n",
  76                         NR_CPUS);
  77
  78                 cpumask_setall(&cpumask);
  79         }
  80
  81         if (!cpumask_test_cpu(0, &cpumask))
  82                 panic("Master cpu (cpu[0]) is missed in cpu possible mask!");
  83
  84         init_cpu_possible(&cpumask);
  85 }
  86
  87 /*
  88  * Called from setup_arch() before calling setup_processor()
  89  *
  90  * - Initialise the CPU possible map early - this describes the CPUs
  91  *   which may be present or become present in the system.
  92  * - Call early smp init hook. This can initialize a specific multi-core
  93  *   IP which is say common to several platforms (hence not part of
  94  *   platform specific int_early() hook)
  95  */
  96 void __init smp_init_cpus(void)
  97 {
  98         arc_init_cpu_possible();
  99
 100         if (plat_smp_ops.init_early_smp)
 101                 plat_smp_ops.init_early_smp();
 102 }
 103
 104 /* called from init ( ) =>  process 1 */
 105 void __init smp_prepare_cpus(unsigned int max_cpus)
 106 {
 107         /*
 108          * if platform didn't set the present map already, do it now
 109          * boot cpu is set to present already by init/main.c
 110          */
 111         if (num_present_cpus() <= 1)
 112                 init_cpu_present(cpu_possible_mask);
 113 }
 114
 115 void __init smp_cpus_done(unsigned int max_cpus)
 116 {
 117
 118 }
 119
 120 /*
 121  * Default smp boot helper for Run-on-reset case where all cores start off
 122  * together. Non-masters need to wait for Master to start running.
 123  * This is implemented using a flag in memory, which Non-masters spin-wait on.
 124  * Master sets it to cpu-id of core to "ungate" it.
 125  */
 126 static volatile int wake_flag;
 127
 128 #ifdef CONFIG_ISA_ARCOMPACT
 129
 130 #define __boot_read(f)          f
 131 #define __boot_write(f, v)      f = v
 132
 133 #else
 134
 135 #define __boot_read(f)          arc_read_uncached_32(&f)
 136 #define __boot_write(f, v)      arc_write_uncached_32(&f, v)
 137
 138 #endif
 139
 140 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
 141 {
 142         BUG_ON(cpu == 0);
 143
 144         __boot_write(wake_flag, cpu);
 145 }
 146
 147 void arc_platform_smp_wait_to_boot(int cpu)
 148 {
 149         /* for halt-on-reset, we've waited already */
 150         if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
 151                 return;
 152
 153         while (__boot_read(wake_flag) != cpu)
 154                 ;
 155
 156         __boot_write(wake_flag, 0);
 157 }
 158
 159 const char *arc_platform_smp_cpuinfo(void)
 160 {
 161         return plat_smp_ops.info ? : "";
 162 }
 163
 164 /*
 165  * The very first "C" code executed by secondary
 166  * Called from asm stub in head.S
 167  * "current"/R25 already setup by low level boot code
 168  */
 169 void start_kernel_secondary(void)
 170 {
 171         struct mm_struct *mm = &init_mm;
 172         unsigned int cpu = smp_processor_id();
 173
 174         /* MMU, Caches, Vector Table, Interrupts etc */
 175         setup_processor();
 176
 177         mmget(mm);
 178         mmgrab(mm);
 179         current->active_mm = mm;
 180         cpumask_set_cpu(cpu, mm_cpumask(mm));
 181
 182         /* Some SMP H/w setup - for each cpu */
 183         if (plat_smp_ops.init_per_cpu)
 184                 plat_smp_ops.init_per_cpu(cpu);
 185
 186         if (machine_desc->init_per_cpu)
 187                 machine_desc->init_per_cpu(cpu);
 188
 189         notify_cpu_starting(cpu);
 190         set_cpu_online(cpu, true);
 191
 192         pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
 193
 194         local_irq_enable();
 195         preempt_disable();
 196         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 197 }
 198
 199 /*
 200  * Called from kernel_init( ) -> smp_init( ) - for each CPU
 201  *
 202  * At this point, Secondary Processor  is "HALT"ed:
 203  *  -It booted, but was halted in head.S
 204  *  -It was configured to halt-on-reset
 205  *  So need to wake it up.
 206  *
 207  * Essential requirements being where to run from (PC) and stack (SP)
 208 */
 209 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 210 {
 211         unsigned long wait_till;
 212
 213         secondary_idle_tsk = idle;
 214
 215         pr_info("Idle Task [%d] %p", cpu, idle);
 216         pr_info("Trying to bring up CPU%u ...\n", cpu);
 217
 218         if (plat_smp_ops.cpu_kick)
 219                 plat_smp_ops.cpu_kick(cpu,
 220                                 (unsigned long)first_lines_of_secondary);
 221         else
 222                 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
 223
 224         /* wait for 1 sec after kicking the secondary */
 225         wait_till = jiffies + HZ;
 226         while (time_before(jiffies, wait_till)) {
 227                 if (cpu_online(cpu))
 228                         break;
 229         }
 230
 231         if (!cpu_online(cpu)) {
 232                 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
 233                 return -1;
 234         }
 235
 236         secondary_idle_tsk = NULL;
 237
 238         return 0;
 239 }
 240
 241 /*
 242  * not supported here
 243  */
 244 int setup_profiling_timer(unsigned int multiplier)
 245 {
 246         return -EINVAL;
 247 }
 248
 249 /*****************************************************************************/
 250 /*              Inter Processor Interrupt Handling                           */
 251 /*****************************************************************************/
 252
 253 enum ipi_msg_type {
 254         IPI_EMPTY = 0,
 255         IPI_RESCHEDULE = 1,
 256         IPI_CALL_FUNC,
 257         IPI_CPU_STOP,
 258 };
 259
 260 /*
 261  * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
 262  * figure out what msg was sent. For those which don't (ARC has dedicated IPI
 263  * IRQ), the msg-type needs to be conveyed via per-cpu data
 264  */
 265
 266 static DEFINE_PER_CPU(unsigned long, ipi_data);
 267
 268 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
 269 {
 270         unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
 271         unsigned long old, new;
 272         unsigned long flags;
 273
 274         pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
 275
 276         local_irq_save(flags);
 277
 278         /*
 279          * Atomically write new msg bit (in case others are writing too),
 280          * and read back old value
 281          */
 282         do {
 283                 new = old = ACCESS_ONCE(*ipi_data_ptr);
 284                 new |= 1U << msg;
 285         } while (cmpxchg(ipi_data_ptr, old, new) != old);
 286
 287         /*
 288          * Call the platform specific IPI kick function, but avoid if possible:
 289          * Only do so if there's no pending msg from other concurrent sender(s).
 290          * Otherwise, recevier will see this msg as well when it takes the
 291          * IPI corresponding to that msg. This is true, even if it is already in
 292          * IPI handler, because !@old means it has not yet dequeued the msg(s)
 293          * so @new msg can be a free-loader
 294          */
 295         if (plat_smp_ops.ipi_send && !old)
 296                 plat_smp_ops.ipi_send(cpu);
 297
 298         local_irq_restore(flags);
 299 }
 300
 301 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 302 {
 303         unsigned int cpu;
 304
 305         for_each_cpu(cpu, callmap)
 306                 ipi_send_msg_one(cpu, msg);
 307 }
 308
 309 void smp_send_reschedule(int cpu)
 310 {
 311         ipi_send_msg_one(cpu, IPI_RESCHEDULE);
 312 }
 313
 314 void smp_send_stop(void)
 315 {
 316         struct cpumask targets;
 317         cpumask_copy(&targets, cpu_online_mask);
 318         cpumask_clear_cpu(smp_processor_id(), &targets);
 319         ipi_send_msg(&targets, IPI_CPU_STOP);
 320 }
 321
 322 void arch_send_call_function_single_ipi(int cpu)
 323 {
 324         ipi_send_msg_one(cpu, IPI_CALL_FUNC);
 325 }
 326
 327 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 328 {
 329         ipi_send_msg(mask, IPI_CALL_FUNC);
 330 }
 331
 332 /*
 333  * ipi_cpu_stop - handle IPI from smp_send_stop()
 334  */
 335 static void ipi_cpu_stop(void)
 336 {
 337         machine_halt();
 338 }
 339
 340 static inline int __do_IPI(unsigned long msg)
 341 {
 342         int rc = 0;
 343
 344         switch (msg) {
 345         case IPI_RESCHEDULE:
 346                 scheduler_ipi();
 347                 break;
 348
 349         case IPI_CALL_FUNC:
 350                 generic_smp_call_function_interrupt();
 351                 break;
 352
 353         case IPI_CPU_STOP:
 354                 ipi_cpu_stop();
 355                 break;
 356
 357         default:
 358                 rc = 1;
 359         }
 360
 361         return rc;
 362 }
 363
 364 /*
 365  * arch-common ISR to handle for inter-processor interrupts
 366  * Has hooks for platform specific IPI
 367  */
 368 irqreturn_t do_IPI(int irq, void *dev_id)
 369 {
 370         unsigned long pending;
 371         unsigned long __maybe_unused copy;
 372
 373         pr_debug("IPI [%ld] received on cpu %d\n",
 374                  *this_cpu_ptr(&ipi_data), smp_processor_id());
 375
 376         if (plat_smp_ops.ipi_clear)
 377                 plat_smp_ops.ipi_clear(irq);
 378
 379         /*
 380          * "dequeue" the msg corresponding to this IPI (and possibly other
 381          * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
 382          */
 383         copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
 384
 385         do {
 386                 unsigned long msg = __ffs(pending);
 387                 int rc;
 388
 389                 rc = __do_IPI(msg);
 390                 if (rc)
 391                         pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
 392                 pending &= ~(1U << msg);
 393         } while (pending);
 394
 395         return IRQ_HANDLED;
 396 }
 397
 398 /*
 399  * API called by platform code to hookup arch-common ISR to their IPI IRQ
 400  *
 401  * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
 402  * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
 403  * request_percpu_irq() below will fail
 404  */
 405 static DEFINE_PER_CPU(int, ipi_dev);
 406
 407 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq)
 408 {
 409         int *dev = per_cpu_ptr(&ipi_dev, cpu);
 410         unsigned int virq = irq_find_mapping(NULL, hwirq);
 411
 412         if (!virq)
 413                 panic("Cannot find virq for root domain and hwirq=%lu", hwirq);
 414
 415         /* Boot cpu calls request, all call enable */
 416         if (!cpu) {
 417                 int rc;
 418
 419                 rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev);
 420                 if (rc)
 421                         panic("Percpu IRQ request failed for %u\n", virq);
 422         }
 423
 424         enable_percpu_irq(virq, 0);
 425
 426         return 0;
 427 }