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.h>
  29 #include <linux/smp.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/cpu.h>
  32
  33 #include <asm/time.h>    /*  timer_interrupt  */
  34 #include <asm/hexagon_vm.h>
  35
  36 #define BASE_IPI_IRQ 26
  37
  38 /*
  39  * cpu_possible_mask needs to be filled out prior to setup_per_cpu_areas
  40  * (which is prior to any of our smp_prepare_cpu crap), in order to set
  41  * up the...  per_cpu areas.
  42  */
  43
  44 struct ipi_data {
  45         unsigned long bits;
  46 };
  47
  48 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
  49
  50 static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
  51                                 int cpu)
  52 {
  53         unsigned long msg = 0;
  54         do {
  55                 msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
  56
  57                 switch (msg) {
  58
  59                 case IPI_TIMER:
  60                         ipi_timer();
  61                         break;
  62
  63                 case IPI_CALL_FUNC:
  64                         generic_smp_call_function_interrupt();
  65                         break;
  66
  67                 case IPI_CPU_STOP:
  68                         /*
  69                          * call vmstop()
  70                          */
  71                         __vmstop();
  72                         break;
  73
  74                 case IPI_RESCHEDULE:
  75                         scheduler_ipi();
  76                         break;
  77                 }
  78         } while (msg < BITS_PER_LONG);
  79 }
  80
  81 /*  Used for IPI call from other CPU's to unmask int  */
  82 void smp_vm_unmask_irq(void *info)
  83 {
  84         __vmintop_locen((long) info);
  85 }
  86
  87
  88 /*
  89  * This is based on Alpha's IPI stuff.
  90  * Supposed to take (int, void*) as args now.
  91  * Specifically, first arg is irq, second is the irq_desc.
  92  */
  93
  94 irqreturn_t handle_ipi(int irq, void *desc)
  95 {
  96         int cpu = smp_processor_id();
  97         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
  98         unsigned long ops;
  99
 100         while ((ops = xchg(&ipi->bits, 0)) != 0)
 101                 __handle_ipi(&ops, ipi, cpu);
 102         return IRQ_HANDLED;
 103 }
 104
 105 void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 106 {
 107         unsigned long flags;
 108         unsigned long cpu;
 109         unsigned long retval;
 110
 111         local_irq_save(flags);
 112
 113         for_each_cpu(cpu, cpumask) {
 114                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 115
 116                 set_bit(msg, &ipi->bits);
 117                 /*  Possible barrier here  */
 118                 retval = __vmintop_post(BASE_IPI_IRQ+cpu);
 119
 120                 if (retval != 0) {
 121                         printk(KERN_ERR "interrupt %ld not configured?\n",
 122                                 BASE_IPI_IRQ+cpu);
 123                 }
 124         }
 125
 126         local_irq_restore(flags);
 127 }
 128
 129 static struct irqaction ipi_intdesc = {
 130         .handler = handle_ipi,
 131         .flags = IRQF_TRIGGER_RISING,
 132         .name = "ipi_handler"
 133 };
 134
 135 void __init smp_prepare_boot_cpu(void)
 136 {
 137 }
 138
 139 /*
 140  * interrupts should already be disabled from the VM
 141  * SP should already be correct; need to set THREADINFO_REG
 142  * to point to current thread info
 143  */
 144
 145 void start_secondary(void)
 146 {
 147         unsigned int cpu;
 148         unsigned long thread_ptr;
 149
 150         /*  Calculate thread_info pointer from stack pointer  */
 151         __asm__ __volatile__(
 152                 "%0 = SP;\n"
 153                 : "=r" (thread_ptr)
 154         );
 155
 156         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 157
 158         __asm__ __volatile__(
 159                 QUOTED_THREADINFO_REG " = %0;\n"
 160                 :
 161                 : "r" (thread_ptr)
 162         );
 163
 164         /*  Set the memory struct  */
 165         atomic_inc(&init_mm.mm_count);
 166         current->active_mm = &init_mm;
 167
 168         cpu = smp_processor_id();
 169
 170         setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
 171
 172         /*  Register the clock_event dummy  */
 173         setup_percpu_clockdev();
 174
 175         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 176
 177         notify_cpu_starting(cpu);
 178
 179         set_cpu_online(cpu, true);
 180
 181         local_irq_enable();
 182
 183         cpu_startup_entry(CPUHP_ONLINE);
 184 }
 185
 186
 187 /*
 188  * called once for each present cpu
 189  * apparently starts up the CPU and then
 190  * maintains control until "cpu_online(cpu)" is set.
 191  */
 192
 193 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 194 {
 195         struct thread_info *thread = (struct thread_info *)idle->stack;
 196         void *stack_start;
 197
 198         thread->cpu = cpu;
 199
 200         /*  Boot to the head.  */
 201         stack_start =  ((void *) thread) + THREAD_SIZE;
 202         __vmstart(start_secondary, stack_start);
 203
 204         while (!cpu_online(cpu))
 205                 barrier();
 206
 207         return 0;
 208 }
 209
 210 void __init smp_cpus_done(unsigned int max_cpus)
 211 {
 212 }
 213
 214 void __init smp_prepare_cpus(unsigned int max_cpus)
 215 {
 216         int i;
 217
 218         /*
 219          * should eventually have some sort of machine
 220          * descriptor that has this stuff
 221          */
 222
 223         /*  Right now, let's just fake it. */
 224         for (i = 0; i < max_cpus; i++)
 225                 set_cpu_present(i, true);
 226
 227         /*  Also need to register the interrupts for IPI  */
 228         if (max_cpus > 1)
 229                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 230 }
 231
 232 void smp_send_reschedule(int cpu)
 233 {
 234         send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 235 }
 236
 237 void smp_send_stop(void)
 238 {
 239         struct cpumask targets;
 240         cpumask_copy(&targets, cpu_online_mask);
 241         cpumask_clear_cpu(smp_processor_id(), &targets);
 242         send_ipi(&targets, IPI_CPU_STOP);
 243 }
 244
 245 void arch_send_call_function_single_ipi(int cpu)
 246 {
 247         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
 248 }
 249
 250 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 251 {
 252         send_ipi(mask, IPI_CALL_FUNC);
 253 }
 254
 255 int setup_profiling_timer(unsigned int multiplier)
 256 {
 257         return -EINVAL;
 258 }
 259
 260 void smp_start_cpus(void)
 261 {
 262         int i;
 263
 264         for (i = 0; i < NR_CPUS; i++)
 265                 set_cpu_possible(i, true);
 266 }