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/system.h>  /*  xchg  */
  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_map 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 __cpuinit 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         set_cpu_online(cpu, true);
 182         while (!cpumask_test_cpu(cpu, cpu_active_mask))
 183                 cpu_relax();
 184         local_irq_enable();
 185
 186         cpu_idle();
 187 }
 188
 189
 190 /*
 191  * called once for each present cpu
 192  * apparently starts up the CPU and then
 193  * maintains control until "cpu_online(cpu)" is set.
 194  */
 195
 196 int __cpuinit __cpu_up(unsigned int cpu)
 197 {
 198         struct task_struct *idle;
 199         struct thread_info *thread;
 200         void *stack_start;
 201
 202         /*  Create new init task for the CPU  */
 203         idle = fork_idle(cpu);
 204         if (IS_ERR(idle))
 205                 panic(KERN_ERR "fork_idle failed\n");
 206
 207         thread = (struct thread_info *)idle->stack;
 208         thread->cpu = cpu;
 209
 210         /*  Boot to the head.  */
 211         stack_start =  ((void *) thread) + THREAD_SIZE;
 212         __vmstart(start_secondary, stack_start);
 213
 214         while (!cpu_isset(cpu, cpu_online_map))
 215                 barrier();
 216
 217         return 0;
 218 }
 219
 220 void __init smp_cpus_done(unsigned int max_cpus)
 221 {
 222 }
 223
 224 void __init smp_prepare_cpus(unsigned int max_cpus)
 225 {
 226         int i;
 227
 228         /*
 229          * should eventually have some sort of machine
 230          * descriptor that has this stuff
 231          */
 232
 233         /*  Right now, let's just fake it. */
 234         for (i = 0; i < max_cpus; i++)
 235                 cpu_set(i, cpu_present_map);
 236
 237         /*  Also need to register the interrupts for IPI  */
 238         if (max_cpus > 1)
 239                 setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
 240 }
 241
 242 void smp_send_reschedule(int cpu)
 243 {
 244         send_ipi(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         send_ipi(&targets, IPI_CPU_STOP);
 253 }
 254
 255 void arch_send_call_function_single_ipi(int cpu)
 256 {
 257         send_ipi(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 258 }
 259
 260 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 261 {
 262         send_ipi(mask, IPI_CALL_FUNC);
 263 }
 264
 265 int setup_profiling_timer(unsigned int multiplier)
 266 {
 267         return -EINVAL;
 268 }
 269
 270 void smp_start_cpus(void)
 271 {
 272         int i;
 273
 274         for (i = 0; i < NR_CPUS; i++)
 275                 cpu_set(i, cpu_possible_map);
 276 }