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         /* Some SMP H/w setup - for each cpu */
 130         if (plat_smp_ops.init_per_cpu)
 131                 plat_smp_ops.init_per_cpu(cpu);
 132
 133         if (machine_desc->init_per_cpu)
 134                 machine_desc->init_per_cpu(cpu);
 135
 136         notify_cpu_starting(cpu);
 137         set_cpu_online(cpu, true);
 138
 139         pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
 140
 141         local_irq_enable();
 142         preempt_disable();
 143         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 144 }
 145
 146 /*
 147  * Called from kernel_init( ) -> smp_init( ) - for each CPU
 148  *
 149  * At this point, Secondary Processor  is "HALT"ed:
 150  *  -It booted, but was halted in head.S
 151  *  -It was configured to halt-on-reset
 152  *  So need to wake it up.
 153  *
 154  * Essential requirements being where to run from (PC) and stack (SP)
 155 */
 156 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 157 {
 158         unsigned long wait_till;
 159
 160         secondary_idle_tsk = idle;
 161
 162         pr_info("Idle Task [%d] %p", cpu, idle);
 163         pr_info("Trying to bring up CPU%u ...\n", cpu);
 164
 165         if (plat_smp_ops.cpu_kick)
 166                 plat_smp_ops.cpu_kick(cpu,
 167                                 (unsigned long)first_lines_of_secondary);
 168         else
 169                 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
 170
 171         /* wait for 1 sec after kicking the secondary */
 172         wait_till = jiffies + HZ;
 173         while (time_before(jiffies, wait_till)) {
 174                 if (cpu_online(cpu))
 175                         break;
 176         }
 177
 178         if (!cpu_online(cpu)) {
 179                 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
 180                 return -1;
 181         }
 182
 183         secondary_idle_tsk = NULL;
 184
 185         return 0;
 186 }
 187
 188 /*
 189  * not supported here
 190  */
 191 int setup_profiling_timer(unsigned int multiplier)
 192 {
 193         return -EINVAL;
 194 }
 195
 196 /*****************************************************************************/
 197 /*              Inter Processor Interrupt Handling                           */
 198 /*****************************************************************************/
 199
 200 enum ipi_msg_type {
 201         IPI_EMPTY = 0,
 202         IPI_RESCHEDULE = 1,
 203         IPI_CALL_FUNC,
 204         IPI_CPU_STOP,
 205 };
 206
 207 /*
 208  * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
 209  * figure out what msg was sent. For those which don't (ARC has dedicated IPI
 210  * IRQ), the msg-type needs to be conveyed via per-cpu data
 211  */
 212
 213 static DEFINE_PER_CPU(unsigned long, ipi_data);
 214
 215 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
 216 {
 217         unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
 218         unsigned long old, new;
 219         unsigned long flags;
 220
 221         pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
 222
 223         local_irq_save(flags);
 224
 225         /*
 226          * Atomically write new msg bit (in case others are writing too),
 227          * and read back old value
 228          */
 229         do {
 230                 new = old = ACCESS_ONCE(*ipi_data_ptr);
 231                 new |= 1U << msg;
 232         } while (cmpxchg(ipi_data_ptr, old, new) != old);
 233
 234         /*
 235          * Call the platform specific IPI kick function, but avoid if possible:
 236          * Only do so if there's no pending msg from other concurrent sender(s).
 237          * Otherwise, recevier will see this msg as well when it takes the
 238          * IPI corresponding to that msg. This is true, even if it is already in
 239          * IPI handler, because !@old means it has not yet dequeued the msg(s)
 240          * so @new msg can be a free-loader
 241          */
 242         if (plat_smp_ops.ipi_send && !old)
 243                 plat_smp_ops.ipi_send(cpu);
 244
 245         local_irq_restore(flags);
 246 }
 247
 248 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 249 {
 250         unsigned int cpu;
 251
 252         for_each_cpu(cpu, callmap)
 253                 ipi_send_msg_one(cpu, msg);
 254 }
 255
 256 void smp_send_reschedule(int cpu)
 257 {
 258         ipi_send_msg_one(cpu, IPI_RESCHEDULE);
 259 }
 260
 261 void smp_send_stop(void)
 262 {
 263         struct cpumask targets;
 264         cpumask_copy(&targets, cpu_online_mask);
 265         cpumask_clear_cpu(smp_processor_id(), &targets);
 266         ipi_send_msg(&targets, IPI_CPU_STOP);
 267 }
 268
 269 void arch_send_call_function_single_ipi(int cpu)
 270 {
 271         ipi_send_msg_one(cpu, IPI_CALL_FUNC);
 272 }
 273
 274 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 275 {
 276         ipi_send_msg(mask, IPI_CALL_FUNC);
 277 }
 278
 279 /*
 280  * ipi_cpu_stop - handle IPI from smp_send_stop()
 281  */
 282 static void ipi_cpu_stop(void)
 283 {
 284         machine_halt();
 285 }
 286
 287 static inline int __do_IPI(unsigned long msg)
 288 {
 289         int rc = 0;
 290
 291         switch (msg) {
 292         case IPI_RESCHEDULE:
 293                 scheduler_ipi();
 294                 break;
 295
 296         case IPI_CALL_FUNC:
 297                 generic_smp_call_function_interrupt();
 298                 break;
 299
 300         case IPI_CPU_STOP:
 301                 ipi_cpu_stop();
 302                 break;
 303
 304         default:
 305                 rc = 1;
 306         }
 307
 308         return rc;
 309 }
 310
 311 /*
 312  * arch-common ISR to handle for inter-processor interrupts
 313  * Has hooks for platform specific IPI
 314  */
 315 irqreturn_t do_IPI(int irq, void *dev_id)
 316 {
 317         unsigned long pending;
 318         unsigned long __maybe_unused copy;
 319
 320         pr_debug("IPI [%ld] received on cpu %d\n",
 321                  *this_cpu_ptr(&ipi_data), smp_processor_id());
 322
 323         if (plat_smp_ops.ipi_clear)
 324                 plat_smp_ops.ipi_clear(irq);
 325
 326         /*
 327          * "dequeue" the msg corresponding to this IPI (and possibly other
 328          * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
 329          */
 330         copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
 331
 332         do {
 333                 unsigned long msg = __ffs(pending);
 334                 int rc;
 335
 336                 rc = __do_IPI(msg);
 337                 if (rc)
 338                         pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
 339                 pending &= ~(1U << msg);
 340         } while (pending);
 341
 342         return IRQ_HANDLED;
 343 }
 344
 345 /*
 346  * API called by platform code to hookup arch-common ISR to their IPI IRQ
 347  *
 348  * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
 349  * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
 350  * request_percpu_irq() below will fail
 351  */
 352 static DEFINE_PER_CPU(int, ipi_dev);
 353
 354 int smp_ipi_irq_setup(int cpu, int irq)
 355 {
 356         int *dev = per_cpu_ptr(&ipi_dev, cpu);
 357
 358         /* Boot cpu calls request, all call enable */
 359         if (!cpu) {
 360                 int rc;
 361
 362                 rc = request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev);
 363                 if (rc)
 364                         panic("Percpu IRQ request failed for %d\n", irq);
 365         }
 366
 367         enable_percpu_irq(irq, 0);
 368
 369         return 0;
 370 }