linux/arch/hexagon/kernel/smp.c
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   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
  44struct ipi_data {
  45        unsigned long bits;
  46};
  47
  48static DEFINE_PER_CPU(struct ipi_data, ipi_data);
  49
  50static 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  */
  82void 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
  94irqreturn_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
 105void 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
 129static struct irqaction ipi_intdesc = {
 130        .handler = handle_ipi,
 131        .flags = IRQF_TRIGGER_RISING,
 132        .name = "ipi_handler"
 133};
 134
 135void __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
 145void 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
 193int __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
 210void __init smp_cpus_done(unsigned int max_cpus)
 211{
 212}
 213
 214void __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
 232void smp_send_reschedule(int cpu)
 233{
 234        send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
 235}
 236
 237void 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
 245void arch_send_call_function_single_ipi(int cpu)
 246{
 247        send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
 248}
 249
 250void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 251{
 252        send_ipi(mask, IPI_CALL_FUNC);
 253}
 254
 255int setup_profiling_timer(unsigned int multiplier)
 256{
 257        return -EINVAL;
 258}
 259
 260void smp_start_cpus(void)
 261{
 262        int i;
 263
 264        for (i = 0; i < NR_CPUS; i++)
 265                set_cpu_possible(i, true);
 266}
 267