LXR linux/arch/powerpc/platforms/cell/smp.c

   1/*
   2 * SMP support for BPA machines.
   3 *
   4 * Dave Engebretsen, Peter Bergner, and
   5 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
   6 *
   7 * Plus various changes from other IBM teams...
   8 *
   9 *      This program is free software; you can redistribute it and/or
  10 *      modify it under the terms of the GNU General Public License
  11 *      as published by the Free Software Foundation; either version
  12 *      2 of the License, or (at your option) any later version.
  13 */
  14
  15#undef DEBUG
  16
  17#include <linux/kernel.h>
  18#include <linux/sched.h>
  19#include <linux/smp.h>
  20#include <linux/interrupt.h>
  21#include <linux/delay.h>
  22#include <linux/init.h>
  23#include <linux/spinlock.h>
  24#include <linux/cache.h>
  25#include <linux/err.h>
  26#include <linux/device.h>
  27#include <linux/cpu.h>
  28
  29#include <asm/ptrace.h>
  30#include <linux/atomic.h>
  31#include <asm/irq.h>
  32#include <asm/page.h>
  33#include <asm/pgtable.h>
  34#include <asm/io.h>
  35#include <asm/prom.h>
  36#include <asm/smp.h>
  37#include <asm/paca.h>
  38#include <asm/machdep.h>
  39#include <asm/cputable.h>
  40#include <asm/firmware.h>
  41#include <asm/rtas.h>
  42#include <asm/cputhreads.h>
  43#include <asm/code-patching.h>
  44
  45#include "interrupt.h"
  46#include <asm/udbg.h>
  47
  48#ifdef DEBUG
  49#define DBG(fmt...) udbg_printf(fmt)
  50#else
  51#define DBG(fmt...)
  52#endif
  53
  54/*
  55 * The Primary thread of each non-boot processor was started from the OF client
  56 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  57 */
  58static cpumask_t of_spin_map;
  59
  60/**
  61 * smp_startup_cpu() - start the given cpu
  62 *
  63 * At boot time, there is nothing to do for primary threads which were
  64 * started from Open Firmware.  For anything else, call RTAS with the
  65 * appropriate start location.
  66 *
  67 * Returns:
  68 *      0       - failure
  69 *      1       - success
  70 */
  71static inline int smp_startup_cpu(unsigned int lcpu)
  72{
  73        int status;
  74        unsigned long start_here =
  75                        __pa(ppc_function_entry(generic_secondary_smp_init));
  76        unsigned int pcpu;
  77        int start_cpu;
  78
  79        if (cpumask_test_cpu(lcpu, &of_spin_map))
  80                /* Already started by OF and sitting in spin loop */
  81                return 1;
  82
  83        pcpu = get_hard_smp_processor_id(lcpu);
  84
  85        /* Fixup atomic count: it exited inside IRQ handler. */
  86        task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
  87
  88        /*
  89         * If the RTAS start-cpu token does not exist then presume the
  90         * cpu is already spinning.
  91         */
  92        start_cpu = rtas_token("start-cpu");
  93        if (start_cpu == RTAS_UNKNOWN_SERVICE)
  94                return 1;
  95
  96        status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
  97        if (status != 0) {
  98                printk(KERN_ERR "start-cpu failed: %i\n", status);
  99                return 0;
 100        }
 101
 102        return 1;
 103}
 104
 105static void smp_cell_setup_cpu(int cpu)
 106{
 107        if (cpu != boot_cpuid)
 108                iic_setup_cpu();
 109
 110        /*
 111         * change default DABRX to allow user watchpoints
 112         */
 113        mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
 114}
 115
 116static int smp_cell_kick_cpu(int nr)
 117{
 118        BUG_ON(nr < 0 || nr >= NR_CPUS);
 119
 120        if (!smp_startup_cpu(nr))
 121                return -ENOENT;
 122
 123        /*
 124         * The processor is currently spinning, waiting for the
 125         * cpu_start field to become non-zero After we set cpu_start,
 126         * the processor will continue on to secondary_start
 127         */
 128        paca[nr].cpu_start = 1;
 129
 130        return 0;
 131}
 132
 133static struct smp_ops_t bpa_iic_smp_ops = {
 134        .message_pass   = iic_message_pass,
 135        .probe          = iic_request_IPIs,
 136        .kick_cpu       = smp_cell_kick_cpu,
 137        .setup_cpu      = smp_cell_setup_cpu,
 138        .cpu_bootable   = smp_generic_cpu_bootable,
 139};
 140
 141/* This is called very early */
 142void __init smp_init_cell(void)
 143{
 144        int i;
 145
 146        DBG(" -> smp_init_cell()\n");
 147
 148        smp_ops = &bpa_iic_smp_ops;
 149
 150        /* Mark threads which are still spinning in hold loops. */
 151        if (cpu_has_feature(CPU_FTR_SMT)) {
 152                for_each_present_cpu(i) {
 153                        if (cpu_thread_in_core(i) == 0)
 154                                cpumask_set_cpu(i, &of_spin_map);
 155                }
 156        } else
 157                cpumask_copy(&of_spin_map, cpu_present_mask);
 158
 159        cpumask_clear_cpu(boot_cpuid, &of_spin_map);
 160
 161        /* Non-lpar has additional take/give timebase */
 162        if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 163                smp_ops->give_timebase = rtas_give_timebase;
 164                smp_ops->take_timebase = rtas_take_timebase;
 165        }
 166
 167        DBG(" <- smp_init_cell()\n");
 168}
 169