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