arch/hexagon/kernel/smp.c

   1 /*
   2  * SMP support for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, Code Aurora Forum. 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
  32 #include <asm/time.h>    /*  timer_interrupt  */
  33 #include <asm/hexagon_vm.h>
  34
  35 #define BASE_IPI_IRQ 26
  36
  37 /*
  38  * cpu_possible_map needs to be filled out prior to setup_per_cpu_areas
  39  * (which is prior to any of our smp_prepare_cpu crap), in order to set
  40  * up the...  per_cpu areas.
  41  */
  42
  43 struct ipi_data {
  44         unsigned long bits;
  45 };
  46
  47 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
  48
  49 static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
  50                                 int cpu)
  51 {
  52         unsigned long msg = 0;
  53         do {
  54                 msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
  55
  56                 switch (msg) {
  57
  58                 case IPI_TIMER:
  59                         ipi_timer();
  60                         break;
  61
  62                 case IPI_CALL_FUNC:
  63                         generic_smp_call_function_interrupt();
  64                         break;
  65
  66                 case IPI_CALL_FUNC_SINGLE:
  67                         generic_smp_call_function_single_interrupt();
  68                         break;
  69
  70                 case IPI_CPU_STOP:
  71                         /*
  72                          * call vmstop()
  73                          */
  74                         __vmstop();
  75                         break;
  76
  77                 case IPI_RESCHEDULE:
  78                         scheduler_ipi();
  79                         break;
  80                 }
  81         } while (msg < BITS_PER_LONG);
  82 }
  83
  84 /*  Used for IPI call from other CPU's to unmask int  */
  85 void smp_vm_unmask_irq(void *info)
  86 {
  87         __vmintop_locen((long) info);
  88 }
  89
  90
  91 /*
  92  * This is based on Alpha's IPI stuff.
  93  * Supposed to take (int, void*) as args now.
  94  * Specifically, first arg is irq, second is the irq_desc.
  95  */
  96
  97 irqreturn_t handle_ipi(int irq, void *desc)
  98 {
  99         int cpu = smp_processor_id();
 100         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 101         unsigned long ops;
 102
 103         while ((ops = xchg(&ipi->bits, 0)) != 0)
 104                 __handle_ipi(&ops, ipi, cpu);
 105         return IRQ_HANDLED;
 106 }
 107
 108 void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 109 {
 110         unsigned long flags;
 111         unsigned long cpu;
 112         unsigned long retval;
 113
 114         local_irq_save(flags);
 115
 116         for_each_cpu(cpu, cpumask) {
 117                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 118
 119                 set_bit(msg, &ipi->bits);
 120                 /*  Possible barrier here  */
 121                 retval = __vmintop_post(BASE_IPI_IRQ+cpu);
 122
 123                 if (retval != 0) {
 124                         printk(KERN_ERR "interrupt %ld not configured?\n",
 125                                 BASE_IPI_IRQ+cpu);
 126                 }
 127         }
 128
 129         local_irq_restore(flags);
 130 }
 131
 132 static struct irqaction ipi_intdesc = {
 133         .handler = handle_ipi,
 134         .flags = IRQF_TRIGGER_RISING,
 135         .name = "ipi_handler"
 136 };
 137
 138 void __init smp_prepare_boot_cpu(void)
 139 {
 140 }
 141
 142 /*
 143  * interrupts should already be disabled from the VM
 144  * SP should already be correct; need to set THREADINFO_REG
 145  * to point to current thread info
 146  */
 147
 148 void __cpuinit start_secondary(void)
 149 {
 150         unsigned int cpu;
 151         unsigned long thread_ptr;
 152
 153         /*  Calculate thread_info pointer from stack pointer  */
 154         __asm__ __volatile__(
 155                 "%0 = SP;\n"
 156                 : "=r" (thread_ptr)
 157         );
 158
 159         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 160
 161         __asm__ __volatile__(
 162                 QUOTED_THREADINFO_REG " = %0;\n"
 163                 :
 164                 : "r" (thread_ptr)
 165         );
 166
 167         /*  Set the memory struct  */
 168         atomic_inc(&init_mm.mm_count);
 169         current->active_mm = &init_mm;
 170
 171         cpu = smp_processor_id();
 172
 173         setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
 174
 175         /*  Register the clock_event dummy  */
 176         setup_percpu_clockdev();
 177
 178         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 179
 180         set_cpu_online(cpu, true);
 181         local_irq_enable();
 182
 183         cpu_idle();
 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 __cpuinit __cpu_up(unsigned int cpu)
 194 {
 195         struct task_struct *idle;
 196         struct thread_info *thread;
 197         void *stack_start;
 198
 199         /*  Create new init task for the CPU  */
 200         idle = fork_idle(cpu);
 201         if (IS_ERR(idle))
 202                 panic(KERN_ERR "fork_idle failed\n");
 203
 204         thread = (struct thread_info *)idle->stack;
 205         thread->cpu = cpu;
 206
 207         /*  Boot to the head.  */
 208         stack_start =  ((void *) thread) + THREAD_SIZE;
 209         __vmstart(start_secondary, stack_start);
 210
 211         while (!cpu_isset(cpu, cpu_online_map))
 212                 barrier();
 213
 214         return 0;
 215 }
 216
 217 void __init smp_cpus_done(unsigned int max_cpus)
 218 {
 219 }
 220
 221 void __init smp_prepare_cpus(unsigned int max_cpus)
 222 {
 223         int i;
 224
 225         /*
 226          * should eventually have some sort of machine
 227          * descriptor that has this stuff
 228          */
 229
 230         /*  Right now, let's just fake it. */
 231         for (i = 0; i < max_cpus; i++)
 232                 cpu_set(i, cpu_present_map);
 233
 234         /*  Also need to register the interrupts for IPI  */
 235         if (max_cpus > 1)
 236                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 237 }
 238
 239 void smp_send_reschedule(int cpu)
 240 {
 241         send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 242 }
 243
 244 void smp_send_stop(void)
 245 {
 246         struct cpumask targets;
 247         cpumask_copy(&targets, cpu_online_mask);
 248         cpumask_clear_cpu(smp_processor_id(), &targets);
 249         send_ipi(&targets, IPI_CPU_STOP);
 250 }
 251
 252 void arch_send_call_function_single_ipi(int cpu)
 253 {
 254         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 255 }
 256
 257 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 258 {
 259         send_ipi(mask, IPI_CALL_FUNC);
 260 }
 261
 262 int setup_profiling_timer(unsigned int multiplier)
 263 {
 264         return -EINVAL;
 265 }
 266
 267 void smp_start_cpus(void)
 268 {
 269         int i;
 270
 271         for (i = 0; i < NR_CPUS; i++)
 272                 cpu_set(i, cpu_possible_map);
 273 }