arch/hexagon/kernel/smp.c

   1 /*
   2  * SMP support for Hexagon
   3  *
   4  * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/err.h>
  22 #include <linux/errno.h>
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/module.h>
  27 #include <linux/percpu.h>
  28 #include <linux/sched/mm.h>
  29 #include <linux/smp.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/cpu.h>
  32 #include <linux/mm_types.h>
  33
  34 #include <asm/time.h>    /*  timer_interrupt  */
  35 #include <asm/hexagon_vm.h>
  36
  37 #define BASE_IPI_IRQ 26
  38
  39 /*
  40  * cpu_possible_mask needs to be filled out prior to setup_per_cpu_areas
  41  * (which is prior to any of our smp_prepare_cpu crap), in order to set
  42  * up the...  per_cpu areas.
  43  */
  44
  45 struct ipi_data {
  46         unsigned long bits;
  47 };
  48
  49 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
  50
  51 static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
  52                                 int cpu)
  53 {
  54         unsigned long msg = 0;
  55         do {
  56                 msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
  57
  58                 switch (msg) {
  59
  60                 case IPI_TIMER:
  61                         ipi_timer();
  62                         break;
  63
  64                 case IPI_CALL_FUNC:
  65                         generic_smp_call_function_interrupt();
  66                         break;
  67
  68                 case IPI_CPU_STOP:
  69                         /*
  70                          * call vmstop()
  71                          */
  72                         __vmstop();
  73                         break;
  74
  75                 case IPI_RESCHEDULE:
  76                         scheduler_ipi();
  77                         break;
  78                 }
  79         } while (msg < BITS_PER_LONG);
  80 }
  81
  82 /*  Used for IPI call from other CPU's to unmask int  */
  83 void smp_vm_unmask_irq(void *info)
  84 {
  85         __vmintop_locen((long) info);
  86 }
  87
  88
  89 /*
  90  * This is based on Alpha's IPI stuff.
  91  * Supposed to take (int, void*) as args now.
  92  * Specifically, first arg is irq, second is the irq_desc.
  93  */
  94
  95 irqreturn_t handle_ipi(int irq, void *desc)
  96 {
  97         int cpu = smp_processor_id();
  98         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
  99         unsigned long ops;
 100
 101         while ((ops = xchg(&ipi->bits, 0)) != 0)
 102                 __handle_ipi(&ops, ipi, cpu);
 103         return IRQ_HANDLED;
 104 }
 105
 106 void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 107 {
 108         unsigned long flags;
 109         unsigned long cpu;
 110         unsigned long retval;
 111
 112         local_irq_save(flags);
 113
 114         for_each_cpu(cpu, cpumask) {
 115                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 116
 117                 set_bit(msg, &ipi->bits);
 118                 /*  Possible barrier here  */
 119                 retval = __vmintop_post(BASE_IPI_IRQ+cpu);
 120
 121                 if (retval != 0) {
 122                         printk(KERN_ERR "interrupt %ld not configured?\n",
 123                                 BASE_IPI_IRQ+cpu);
 124                 }
 125         }
 126
 127         local_irq_restore(flags);
 128 }
 129
 130 static struct irqaction ipi_intdesc = {
 131         .handler = handle_ipi,
 132         .flags = IRQF_TRIGGER_RISING,
 133         .name = "ipi_handler"
 134 };
 135
 136 void __init smp_prepare_boot_cpu(void)
 137 {
 138 }
 139
 140 /*
 141  * interrupts should already be disabled from the VM
 142  * SP should already be correct; need to set THREADINFO_REG
 143  * to point to current thread info
 144  */
 145
 146 void start_secondary(void)
 147 {
 148         unsigned int cpu;
 149         unsigned long thread_ptr;
 150
 151         /*  Calculate thread_info pointer from stack pointer  */
 152         __asm__ __volatile__(
 153                 "%0 = SP;\n"
 154                 : "=r" (thread_ptr)
 155         );
 156
 157         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 158
 159         __asm__ __volatile__(
 160                 QUOTED_THREADINFO_REG " = %0;\n"
 161                 :
 162                 : "r" (thread_ptr)
 163         );
 164
 165         /*  Set the memory struct  */
 166         mmgrab(&init_mm);
 167         current->active_mm = &init_mm;
 168
 169         cpu = smp_processor_id();
 170
 171         setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
 172
 173         /*  Register the clock_event dummy  */
 174         setup_percpu_clockdev();
 175
 176         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 177
 178         notify_cpu_starting(cpu);
 179
 180         set_cpu_online(cpu, true);
 181
 182         local_irq_enable();
 183
 184         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 185 }
 186
 187
 188 /*
 189  * called once for each present cpu
 190  * apparently starts up the CPU and then
 191  * maintains control until "cpu_online(cpu)" is set.
 192  */
 193
 194 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 195 {
 196         struct thread_info *thread = (struct thread_info *)idle->stack;
 197         void *stack_start;
 198
 199         thread->cpu = cpu;
 200
 201         /*  Boot to the head.  */
 202         stack_start =  ((void *) thread) + THREAD_SIZE;
 203         __vmstart(start_secondary, stack_start);
 204
 205         while (!cpu_online(cpu))
 206                 barrier();
 207
 208         return 0;
 209 }
 210
 211 void __init smp_cpus_done(unsigned int max_cpus)
 212 {
 213 }
 214
 215 void __init smp_prepare_cpus(unsigned int max_cpus)
 216 {
 217         int i;
 218
 219         /*
 220          * should eventually have some sort of machine
 221          * descriptor that has this stuff
 222          */
 223
 224         /*  Right now, let's just fake it. */
 225         for (i = 0; i < max_cpus; i++)
 226                 set_cpu_present(i, true);
 227
 228         /*  Also need to register the interrupts for IPI  */
 229         if (max_cpus > 1)
 230                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 231 }
 232
 233 void smp_send_reschedule(int cpu)
 234 {
 235         send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 236 }
 237
 238 void smp_send_stop(void)
 239 {
 240         struct cpumask targets;
 241         cpumask_copy(&targets, cpu_online_mask);
 242         cpumask_clear_cpu(smp_processor_id(), &targets);
 243         send_ipi(&targets, IPI_CPU_STOP);
 244 }
 245
 246 void arch_send_call_function_single_ipi(int cpu)
 247 {
 248         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
 249 }
 250
 251 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 252 {
 253         send_ipi(mask, IPI_CALL_FUNC);
 254 }
 255
 256 int setup_profiling_timer(unsigned int multiplier)
 257 {
 258         return -EINVAL;
 259 }
 260
 261 void smp_start_cpus(void)
 262 {
 263         int i;
 264
 265         for (i = 0; i < NR_CPUS; i++)
 266                 set_cpu_possible(i, true);
 267 }