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/module.h>
  16 #include <linux/init.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/sched.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/profile.h>
  21 #include <linux/errno.h>
  22 #include <linux/err.h>
  23 #include <linux/mm.h>
  24 #include <linux/cpu.h>
  25 #include <linux/smp.h>
  26 #include <linux/irq.h>
  27 #include <linux/delay.h>
  28 #include <linux/atomic.h>
  29 #include <linux/percpu.h>
  30 #include <linux/cpumask.h>
  31 #include <linux/spinlock_types.h>
  32 #include <linux/reboot.h>
  33 #include <asm/processor.h>
  34 #include <asm/setup.h>
  35 #include <asm/mach_desc.h>
  36
  37 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  38 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  39
  40 struct plat_smp_ops  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  * Initialise the CPU possible map early - this describes the CPUs
  52  * which may be present or become present in the system.
  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
  62 /* called from init ( ) =>  process 1 */
  63 void __init smp_prepare_cpus(unsigned int max_cpus)
  64 {
  65         int i;
  66
  67         /*
  68          * Initialise the present map, which describes the set of CPUs
  69          * actually populated at the present time.
  70          */
  71         for (i = 0; i < max_cpus; i++)
  72                 set_cpu_present(i, true);
  73 }
  74
  75 void __init smp_cpus_done(unsigned int max_cpus)
  76 {
  77
  78 }
  79
  80 /*
  81  * After power-up, a non Master CPU needs to wait for Master to kick start it
  82  *
  83  * The default implementation halts
  84  *
  85  * This relies on platform specific support allowing Master to directly set
  86  * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
  87  *
  88  * In lack of such h/w assist, platforms can override this function
  89  *   - make this function busy-spin on a token, eventually set by Master
  90  *     (from arc_platform_smp_wakeup_cpu())
  91  *   - Once token is available, jump to @first_lines_of_secondary
  92  *     (using inline asm).
  93  *
  94  * Alert: can NOT use stack here as it has not been determined/setup for CPU.
  95  *        If it turns out to be elaborate, it's better to code it in assembly
  96  *
  97  */
  98 void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
  99 {
 100         /*
 101          * As a hack for debugging - since debugger will single-step over the
 102          * FLAG insn - wrap the halt itself it in a self loop
 103          */
 104         __asm__ __volatile__(
 105         "1:             \n"
 106         "       flag 1  \n"
 107         "       b 1b    \n");
 108 }
 109
 110 const char *arc_platform_smp_cpuinfo(void)
 111 {
 112         return plat_smp_ops.info;
 113 }
 114
 115 /*
 116  * The very first "C" code executed by secondary
 117  * Called from asm stub in head.S
 118  * "current"/R25 already setup by low level boot code
 119  */
 120 void start_kernel_secondary(void)
 121 {
 122         struct mm_struct *mm = &init_mm;
 123         unsigned int cpu = smp_processor_id();
 124
 125         /* MMU, Caches, Vector Table, Interrupts etc */
 126         setup_processor();
 127
 128         atomic_inc(&mm->mm_users);
 129         atomic_inc(&mm->mm_count);
 130         current->active_mm = mm;
 131
 132         notify_cpu_starting(cpu);
 133         set_cpu_online(cpu, true);
 134
 135         pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
 136
 137         if (machine_desc->init_smp)
 138                 machine_desc->init_smp(smp_processor_id());
 139
 140         arc_local_timer_setup(cpu);
 141
 142         local_irq_enable();
 143         preempt_disable();
 144         cpu_startup_entry(CPUHP_ONLINE);
 145 }
 146
 147 /*
 148  * Called from kernel_init( ) -> smp_init( ) - for each CPU
 149  *
 150  * At this point, Secondary Processor  is "HALT"ed:
 151  *  -It booted, but was halted in head.S
 152  *  -It was configured to halt-on-reset
 153  *  So need to wake it up.
 154  *
 155  * Essential requirements being where to run from (PC) and stack (SP)
 156 */
 157 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 158 {
 159         unsigned long wait_till;
 160
 161         secondary_idle_tsk = idle;
 162
 163         pr_info("Idle Task [%d] %p", cpu, idle);
 164         pr_info("Trying to bring up CPU%u ...\n", cpu);
 165
 166         if (plat_smp_ops.cpu_kick)
 167                 plat_smp_ops.cpu_kick(cpu,
 168                                 (unsigned long)first_lines_of_secondary);
 169
 170         /* wait for 1 sec after kicking the secondary */
 171         wait_till = jiffies + HZ;
 172         while (time_before(jiffies, wait_till)) {
 173                 if (cpu_online(cpu))
 174                         break;
 175         }
 176
 177         if (!cpu_online(cpu)) {
 178                 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
 179                 return -1;
 180         }
 181
 182         secondary_idle_tsk = NULL;
 183
 184         return 0;
 185 }
 186
 187 /*
 188  * not supported here
 189  */
 190 int __init setup_profiling_timer(unsigned int multiplier)
 191 {
 192         return -EINVAL;
 193 }
 194
 195 /*****************************************************************************/
 196 /*              Inter Processor Interrupt Handling                           */
 197 /*****************************************************************************/
 198
 199 /*
 200  * structures for inter-processor calls
 201  * A Collection of single bit ipi messages
 202  *
 203  */
 204
 205 /*
 206  * TODO_rajesh investigate tlb message types.
 207  * IPI Timer not needed because each ARC has an individual Interrupting Timer
 208  */
 209 enum ipi_msg_type {
 210         IPI_NOP = 0,
 211         IPI_RESCHEDULE = 1,
 212         IPI_CALL_FUNC,
 213         IPI_CALL_FUNC_SINGLE,
 214         IPI_CPU_STOP
 215 };
 216
 217 struct ipi_data {
 218         unsigned long bits;
 219 };
 220
 221 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
 222
 223 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
 224 {
 225         unsigned long flags;
 226         unsigned int cpu;
 227
 228         local_irq_save(flags);
 229
 230         for_each_cpu(cpu, callmap) {
 231                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 232                 set_bit(msg, &ipi->bits);
 233         }
 234
 235         /* Call the platform specific cross-CPU call function  */
 236         if (plat_smp_ops.ipi_send)
 237                 plat_smp_ops.ipi_send((void *)callmap);
 238
 239         local_irq_restore(flags);
 240 }
 241
 242 void smp_send_reschedule(int cpu)
 243 {
 244         ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
 245 }
 246
 247 void smp_send_stop(void)
 248 {
 249         struct cpumask targets;
 250         cpumask_copy(&targets, cpu_online_mask);
 251         cpumask_clear_cpu(smp_processor_id(), &targets);
 252         ipi_send_msg(&targets, IPI_CPU_STOP);
 253 }
 254
 255 void arch_send_call_function_single_ipi(int cpu)
 256 {
 257         ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 258 }
 259
 260 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 261 {
 262         ipi_send_msg(mask, IPI_CALL_FUNC);
 263 }
 264
 265 /*
 266  * ipi_cpu_stop - handle IPI from smp_send_stop()
 267  */
 268 static void ipi_cpu_stop(unsigned int cpu)
 269 {
 270         machine_halt();
 271 }
 272
 273 static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
 274 {
 275         unsigned long msg = 0;
 276
 277         do {
 278                 msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
 279
 280                 switch (msg) {
 281                 case IPI_RESCHEDULE:
 282                         scheduler_ipi();
 283                         break;
 284
 285                 case IPI_CALL_FUNC:
 286                         generic_smp_call_function_interrupt();
 287                         break;
 288
 289                 case IPI_CALL_FUNC_SINGLE:
 290                         generic_smp_call_function_single_interrupt();
 291                         break;
 292
 293                 case IPI_CPU_STOP:
 294                         ipi_cpu_stop(cpu);
 295                         break;
 296                 }
 297         } while (msg < BITS_PER_LONG);
 298
 299 }
 300
 301 /*
 302  * arch-common ISR to handle for inter-processor interrupts
 303  * Has hooks for platform specific IPI
 304  */
 305 irqreturn_t do_IPI(int irq, void *dev_id)
 306 {
 307         int cpu = smp_processor_id();
 308         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 309         unsigned long ops;
 310
 311         if (plat_smp_ops.ipi_clear)
 312                 plat_smp_ops.ipi_clear(cpu, irq);
 313
 314         /*
 315          * XXX: is this loop really needed
 316          * And do we need to move ipi_clean inside
 317          */
 318         while ((ops = xchg(&ipi->bits, 0)) != 0)
 319                 __do_IPI(&ops, ipi, cpu);
 320
 321         return IRQ_HANDLED;
 322 }
 323
 324 /*
 325  * API called by platform code to hookup arch-common ISR to their IPI IRQ
 326  */
 327 static DEFINE_PER_CPU(int, ipi_dev);
 328 int smp_ipi_irq_setup(int cpu, int irq)
 329 {
 330         int *dev_id = &per_cpu(ipi_dev, smp_processor_id());
 331         return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
 332 }