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

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * SMP support for BPA machines.
   4 *
   5 * Dave Engebretsen, Peter Bergner, and
   6 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
   7 *
   8 * Plus various changes from other IBM teams...
   9 */
  10
  11#undef DEBUG
  12
  13#include <linux/kernel.h>
  14#include <linux/sched.h>
  15#include <linux/smp.h>
  16#include <linux/interrupt.h>
  17#include <linux/delay.h>
  18#include <linux/init.h>
  19#include <linux/spinlock.h>
  20#include <linux/cache.h>
  21#include <linux/err.h>
  22#include <linux/device.h>
  23#include <linux/cpu.h>
  24#include <linux/pgtable.h>
  25
  26#include <asm/ptrace.h>
  27#include <linux/atomic.h>
  28#include <asm/irq.h>
  29#include <asm/page.h>
  30#include <asm/io.h>
  31#include <asm/prom.h>
  32#include <asm/smp.h>
  33#include <asm/paca.h>
  34#include <asm/machdep.h>
  35#include <asm/cputable.h>
  36#include <asm/firmware.h>
  37#include <asm/rtas.h>
  38#include <asm/cputhreads.h>
  39#include <asm/code-patching.h>
  40
  41#include "interrupt.h"
  42#include <asm/udbg.h>
  43
  44#ifdef DEBUG
  45#define DBG(fmt...) udbg_printf(fmt)
  46#else
  47#define DBG(fmt...)
  48#endif
  49
  50/*
  51 * The Primary thread of each non-boot processor was started from the OF client
  52 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  53 */
  54static cpumask_t of_spin_map;
  55
  56/**
  57 * smp_startup_cpu() - start the given cpu
  58 *
  59 * At boot time, there is nothing to do for primary threads which were
  60 * started from Open Firmware.  For anything else, call RTAS with the
  61 * appropriate start location.
  62 *
  63 * Returns:
  64 *      0       - failure
  65 *      1       - success
  66 */
  67static inline int smp_startup_cpu(unsigned int lcpu)
  68{
  69        int status;
  70        unsigned long start_here =
  71                        __pa(ppc_function_entry(generic_secondary_smp_init));
  72        unsigned int pcpu;
  73        int start_cpu;
  74
  75        if (cpumask_test_cpu(lcpu, &of_spin_map))
  76                /* Already started by OF and sitting in spin loop */
  77                return 1;
  78
  79        pcpu = get_hard_smp_processor_id(lcpu);
  80
  81        /* Fixup atomic count: it exited inside IRQ handler. */
  82        task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count     = 0;
  83
  84        /*
  85         * If the RTAS start-cpu token does not exist then presume the
  86         * cpu is already spinning.
  87         */
  88        start_cpu = rtas_token("start-cpu");
  89        if (start_cpu == RTAS_UNKNOWN_SERVICE)
  90                return 1;
  91
  92        status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
  93        if (status != 0) {
  94                printk(KERN_ERR "start-cpu failed: %i\n", status);
  95                return 0;
  96        }
  97
  98        return 1;
  99}
 100
 101static void smp_cell_setup_cpu(int cpu)
 102{
 103        if (cpu != boot_cpuid)
 104                iic_setup_cpu();
 105
 106        /*
 107         * change default DABRX to allow user watchpoints
 108         */
 109        mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER);
 110}
 111
 112static int smp_cell_kick_cpu(int nr)
 113{
 114        if (nr < 0 || nr >= nr_cpu_ids)
 115                return -EINVAL;
 116
 117        if (!smp_startup_cpu(nr))
 118                return -ENOENT;
 119
 120        /*
 121         * The processor is currently spinning, waiting for the
 122         * cpu_start field to become non-zero After we set cpu_start,
 123         * the processor will continue on to secondary_start
 124         */
 125        paca_ptrs[nr]->cpu_start = 1;
 126
 127        return 0;
 128}
 129
 130static struct smp_ops_t bpa_iic_smp_ops = {
 131        .message_pass   = iic_message_pass,
 132        .probe          = iic_request_IPIs,
 133        .kick_cpu       = smp_cell_kick_cpu,
 134        .setup_cpu      = smp_cell_setup_cpu,
 135        .cpu_bootable   = smp_generic_cpu_bootable,
 136};
 137
 138/* This is called very early */
 139void __init smp_init_cell(void)
 140{
 141        int i;
 142
 143        DBG(" -> smp_init_cell()\n");
 144
 145        smp_ops = &bpa_iic_smp_ops;
 146
 147        /* Mark threads which are still spinning in hold loops. */
 148        if (cpu_has_feature(CPU_FTR_SMT)) {
 149                for_each_present_cpu(i) {
 150                        if (cpu_thread_in_core(i) == 0)
 151                                cpumask_set_cpu(i, &of_spin_map);
 152                }
 153        } else
 154                cpumask_copy(&of_spin_map, cpu_present_mask);
 155
 156        cpumask_clear_cpu(boot_cpuid, &of_spin_map);
 157
 158        /* Non-lpar has additional take/give timebase */
 159        if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 160                smp_ops->give_timebase = rtas_give_timebase;
 161                smp_ops->take_timebase = rtas_take_timebase;
 162        }
 163
 164        DBG(" <- smp_init_cell()\n");
 165}
 166