arch/arm/mach-integrator/platsmp.c

   1 /*
   2  *  linux/arch/arm/mach-cintegrator/platsmp.c
   3  *
   4  *  Copyright (C) 2002 ARM Ltd.
   5  *  All Rights Reserved
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/errno.h>
  15 #include <linux/mm.h>
  16
  17 #include <asm/atomic.h>
  18 #include <asm/delay.h>
  19 #include <asm/mmu_context.h>
  20 #include <asm/procinfo.h>
  21 #include <asm/ptrace.h>
  22 #include <asm/smp.h>
  23
  24 extern void integrator_secondary_startup(void);
  25
  26 /*
  27  * control for which core is the next to come out of the secondary
  28  * boot "holding pen"
  29  */
  30 volatile int __cpuinitdata pen_release = -1;
  31 unsigned long __cpuinitdata phys_pen_release = 0;
  32
  33 static DEFINE_SPINLOCK(boot_lock);
  34
  35 void __cpuinit platform_secondary_init(unsigned int cpu)
  36 {
  37         /*
  38          * the primary core may have used a "cross call" soft interrupt
  39          * to get this processor out of WFI in the BootMonitor - make
  40          * sure that we are no longer being sent this soft interrupt
  41          */
  42         smp_cross_call_done(cpumask_of_cpu(cpu));
  43
  44         /*
  45          * if any interrupts are already enabled for the primary
  46          * core (e.g. timer irq), then they will not have been enabled
  47          * for us: do so
  48          */
  49         secondary_scan_irqs();
  50
  51         /*
  52          * let the primary processor know we're out of the
  53          * pen, then head off into the C entry point
  54          */
  55         pen_release = -1;
  56
  57         /*
  58          * Synchronise with the boot thread.
  59          */
  60         spin_lock(&boot_lock);
  61         spin_unlock(&boot_lock);
  62 }
  63
  64 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  65 {
  66         unsigned long timeout;
  67
  68         /*
  69          * set synchronisation state between this boot processor
  70          * and the secondary one
  71          */
  72         spin_lock(&boot_lock);
  73
  74         /*
  75          * The secondary processor is waiting to be released from
  76          * the holding pen - release it, then wait for it to flag
  77          * that it has been released by resetting pen_release.
  78          *
  79          * Note that "pen_release" is the hardware CPU ID, whereas
  80          * "cpu" is Linux's internal ID.
  81          */
  82         pen_release = cpu;
  83
  84         /*
  85          * XXX
  86          *
  87          * This is a later addition to the booting protocol: the
  88          * bootMonitor now puts secondary cores into WFI, so
  89          * poke_milo() no longer gets the cores moving; we need
  90          * to send a soft interrupt to wake the secondary core.
  91          * Use smp_cross_call() for this, since there's little
  92          * point duplicating the code here
  93          */
  94         smp_cross_call(cpumask_of_cpu(cpu));
  95
  96         timeout = jiffies + (1 * HZ);
  97         while (time_before(jiffies, timeout)) {
  98                 if (pen_release == -1)
  99                         break;
 100
 101                 udelay(10);
 102         }
 103
 104         /*
 105          * now the secondary core is starting up let it run its
 106          * calibrations, then wait for it to finish
 107          */
 108         spin_unlock(&boot_lock);
 109
 110         return pen_release != -1 ? -ENOSYS : 0;
 111 }
 112
 113 static void __init poke_milo(void)
 114 {
 115         extern void secondary_startup(void);
 116
 117         /* nobody is to be released from the pen yet */
 118         pen_release = -1;
 119
 120         phys_pen_release = virt_to_phys(&pen_release);
 121
 122         /*
 123          * write the address of secondary startup into the system-wide
 124          * flags register, then clear the bottom two bits, which is what
 125          * BootMonitor is waiting for
 126          */
 127 #if 1
 128 #define CINTEGRATOR_HDR_FLAGSS_OFFSET 0x30
 129         __raw_writel(virt_to_phys(integrator_secondary_startup),
 130                      (IO_ADDRESS(INTEGRATOR_HDR_BASE) +
 131                       CINTEGRATOR_HDR_FLAGSS_OFFSET));
 132 #define CINTEGRATOR_HDR_FLAGSC_OFFSET 0x34
 133         __raw_writel(3,
 134                      (IO_ADDRESS(INTEGRATOR_HDR_BASE) +
 135                       CINTEGRATOR_HDR_FLAGSC_OFFSET));
 136 #endif
 137
 138         mb();
 139 }
 140
 141 void __init smp_prepare_cpus(unsigned int max_cpus)
 142 {
 143         unsigned int ncores = get_core_count();
 144         unsigned int cpu = smp_processor_id();
 145         int i;
 146
 147         /* sanity check */
 148         if (ncores == 0) {
 149                 printk(KERN_ERR
 150                        "Integrator/CP: strange CM count of 0? Default to 1\n");
 151
 152                 ncores = 1;
 153         }
 154
 155         if (ncores > NR_CPUS) {
 156                 printk(KERN_WARNING
 157                        "Integrator/CP: no. of cores (%d) greater than configured "
 158                        "maximum of %d - clipping\n",
 159                        ncores, NR_CPUS);
 160                 ncores = NR_CPUS;
 161         }
 162
 163         /*
 164          * start with some more config for the Boot CPU, now that
 165          * the world is a bit more alive (which was not the case
 166          * when smp_prepare_boot_cpu() was called)
 167          */
 168         smp_store_cpu_info(cpu);
 169
 170         /*
 171          * are we trying to boot more cores than exist?
 172          */
 173         if (max_cpus > ncores)
 174                 max_cpus = ncores;
 175
 176         /*
 177          * Initialise the possible/present maps.
 178          * cpu_possible_map describes the set of CPUs which may be present
 179          * cpu_present_map describes the set of CPUs populated
 180          */
 181         for (i = 0; i < max_cpus; i++) {
 182                 cpu_set(i, cpu_possible_map);
 183                 cpu_set(i, cpu_present_map);
 184         }
 185
 186         /*
 187          * Do we need any more CPUs? If so, then let them know where
 188          * to start. Note that, on modern versions of MILO, the "poke"
 189          * doesn't actually do anything until each individual core is
 190          * sent a soft interrupt to get it out of WFI
 191          */
 192         if (max_cpus > 1)
 193                 poke_milo();
 194 }