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_CALL_FUNC_SINGLE:
  68                         generic_smp_call_function_single_interrupt();
  69                         break;
  70
  71                 case IPI_CPU_STOP:
  72                         /*
  73                          * call vmstop()
  74                          */
  75                         __vmstop();
  76                         break;
  77
  78                 case IPI_RESCHEDULE:
  79                         scheduler_ipi();
  80                         break;
  81                 }
  82         } while (msg < BITS_PER_LONG);
  83 }
  84
  85 /*  Used for IPI call from other CPU's to unmask int  */
  86 void smp_vm_unmask_irq(void *info)
  87 {
  88         __vmintop_locen((long) info);
  89 }
  90
  91
  92 /*
  93  * This is based on Alpha's IPI stuff.
  94  * Supposed to take (int, void*) as args now.
  95  * Specifically, first arg is irq, second is the irq_desc.
  96  */
  97
  98 irqreturn_t handle_ipi(int irq, void *desc)
  99 {
 100         int cpu = smp_processor_id();
 101         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 102         unsigned long ops;
 103
 104         while ((ops = xchg(&ipi->bits, 0)) != 0)
 105                 __handle_ipi(&ops, ipi, cpu);
 106         return IRQ_HANDLED;
 107 }
 108
 109 void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 110 {
 111         unsigned long flags;
 112         unsigned long cpu;
 113         unsigned long retval;
 114
 115         local_irq_save(flags);
 116
 117         for_each_cpu(cpu, cpumask) {
 118                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 119
 120                 set_bit(msg, &ipi->bits);
 121                 /*  Possible barrier here  */
 122                 retval = __vmintop_post(BASE_IPI_IRQ+cpu);
 123
 124                 if (retval != 0) {
 125                         printk(KERN_ERR "interrupt %ld not configured?\n",
 126                                 BASE_IPI_IRQ+cpu);
 127                 }
 128         }
 129
 130         local_irq_restore(flags);
 131 }
 132
 133 static struct irqaction ipi_intdesc = {
 134         .handler = handle_ipi,
 135         .flags = IRQF_TRIGGER_RISING,
 136         .name = "ipi_handler"
 137 };
 138
 139 void __init smp_prepare_boot_cpu(void)
 140 {
 141 }
 142
 143 /*
 144  * interrupts should already be disabled from the VM
 145  * SP should already be correct; need to set THREADINFO_REG
 146  * to point to current thread info
 147  */
 148
 149 void start_secondary(void)
 150 {
 151         unsigned int cpu;
 152         unsigned long thread_ptr;
 153
 154         /*  Calculate thread_info pointer from stack pointer  */
 155         __asm__ __volatile__(
 156                 "%0 = SP;\n"
 157                 : "=r" (thread_ptr)
 158         );
 159
 160         thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
 161
 162         __asm__ __volatile__(
 163                 QUOTED_THREADINFO_REG " = %0;\n"
 164                 :
 165                 : "r" (thread_ptr)
 166         );
 167
 168         /*  Set the memory struct  */
 169         atomic_inc(&init_mm.mm_count);
 170         current->active_mm = &init_mm;
 171
 172         cpu = smp_processor_id();
 173
 174         setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
 175
 176         /*  Register the clock_event dummy  */
 177         setup_percpu_clockdev();
 178
 179         printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
 180
 181         notify_cpu_starting(cpu);
 182
 183         set_cpu_online(cpu, true);
 184
 185         local_irq_enable();
 186
 187         cpu_startup_entry(CPUHP_ONLINE);
 188 }
 189
 190
 191 /*
 192  * called once for each present cpu
 193  * apparently starts up the CPU and then
 194  * maintains control until "cpu_online(cpu)" is set.
 195  */
 196
 197 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 198 {
 199         struct thread_info *thread = (struct thread_info *)idle->stack;
 200         void *stack_start;
 201
 202         thread->cpu = cpu;
 203
 204         /*  Boot to the head.  */
 205         stack_start =  ((void *) thread) + THREAD_SIZE;
 206         __vmstart(start_secondary, stack_start);
 207
 208         while (!cpu_online(cpu))
 209                 barrier();
 210
 211         return 0;
 212 }
 213
 214 void __init smp_cpus_done(unsigned int max_cpus)
 215 {
 216 }
 217
 218 void __init smp_prepare_cpus(unsigned int max_cpus)
 219 {
 220         int i;
 221
 222         /*
 223          * should eventually have some sort of machine
 224          * descriptor that has this stuff
 225          */
 226
 227         /*  Right now, let's just fake it. */
 228         for (i = 0; i < max_cpus; i++)
 229                 set_cpu_present(i, true);
 230
 231         /*  Also need to register the interrupts for IPI  */
 232         if (max_cpus > 1)
 233                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 234 }
 235
 236 void smp_send_reschedule(int cpu)
 237 {
 238         send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 239 }
 240
 241 void smp_send_stop(void)
 242 {
 243         struct cpumask targets;
 244         cpumask_copy(&targets, cpu_online_mask);
 245         cpumask_clear_cpu(smp_processor_id(), &targets);
 246         send_ipi(&targets, IPI_CPU_STOP);
 247 }
 248
 249 void arch_send_call_function_single_ipi(int cpu)
 250 {
 251         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 252 }
 253
 254 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 255 {
 256         send_ipi(mask, IPI_CALL_FUNC);
 257 }
 258
 259 int setup_profiling_timer(unsigned int multiplier)
 260 {
 261         return -EINVAL;
 262 }
 263
 264 void smp_start_cpus(void)
 265 {
 266         int i;
 267
 268         for (i = 0; i < NR_CPUS; i++)
 269                 set_cpu_possible(i, true);
 270 }