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/cacheflush.h>
  19 #include <asm/delay.h>
  20 #include <asm/mmu_context.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         flush_cache_all();
  84
  85         /*
  86          * XXX
  87          *
  88          * This is a later addition to the booting protocol: the
  89          * bootMonitor now puts secondary cores into WFI, so
  90          * poke_milo() no longer gets the cores moving; we need
  91          * to send a soft interrupt to wake the secondary core.
  92          * Use smp_cross_call() for this, since there's little
  93          * point duplicating the code here
  94          */
  95         smp_cross_call(cpumask_of_cpu(cpu));
  96
  97         timeout = jiffies + (1 * HZ);
  98         while (time_before(jiffies, timeout)) {
  99                 if (pen_release == -1)
 100                         break;
 101
 102                 udelay(10);
 103         }
 104
 105         /*
 106          * now the secondary core is starting up let it run its
 107          * calibrations, then wait for it to finish
 108          */
 109         spin_unlock(&boot_lock);
 110
 111         return pen_release != -1 ? -ENOSYS : 0;
 112 }
 113
 114 static void __init poke_milo(void)
 115 {
 116         extern void secondary_startup(void);
 117
 118         /* nobody is to be released from the pen yet */
 119         pen_release = -1;
 120
 121         phys_pen_release = virt_to_phys(&pen_release);
 122
 123         /*
 124          * write the address of secondary startup into the system-wide
 125          * flags register, then clear the bottom two bits, which is what
 126          * BootMonitor is waiting for
 127          */
 128 #if 1
 129 #define CINTEGRATOR_HDR_FLAGSS_OFFSET 0x30
 130         __raw_writel(virt_to_phys(integrator_secondary_startup),
 131                      (IO_ADDRESS(INTEGRATOR_HDR_BASE) +
 132                       CINTEGRATOR_HDR_FLAGSS_OFFSET));
 133 #define CINTEGRATOR_HDR_FLAGSC_OFFSET 0x34
 134         __raw_writel(3,
 135                      (IO_ADDRESS(INTEGRATOR_HDR_BASE) +
 136                       CINTEGRATOR_HDR_FLAGSC_OFFSET));
 137 #endif
 138
 139         mb();
 140 }
 141
 142 /*
 143  * Initialise the CPU possible map early - this describes the CPUs
 144  * which may be present or become present in the system.
 145  */
 146 void __init smp_init_cpus(void)
 147 {
 148         unsigned int i, ncores = get_core_count();
 149
 150         for (i = 0; i < ncores; i++)
 151                 cpu_set(i, cpu_possible_map);
 152 }
 153
 154 void __init smp_prepare_cpus(unsigned int max_cpus)
 155 {
 156         unsigned int ncores = get_core_count();
 157         unsigned int cpu = smp_processor_id();
 158         int i;
 159
 160         /* sanity check */
 161         if (ncores == 0) {
 162                 printk(KERN_ERR
 163                        "Integrator/CP: strange CM count of 0? Default to 1\n");
 164
 165                 ncores = 1;
 166         }
 167
 168         if (ncores > NR_CPUS) {
 169                 printk(KERN_WARNING
 170                        "Integrator/CP: no. of cores (%d) greater than configured "
 171                        "maximum of %d - clipping\n",
 172                        ncores, NR_CPUS);
 173                 ncores = NR_CPUS;
 174         }
 175
 176         /*
 177          * start with some more config for the Boot CPU, now that
 178          * the world is a bit more alive (which was not the case
 179          * when smp_prepare_boot_cpu() was called)
 180          */
 181         smp_store_cpu_info(cpu);
 182
 183         /*
 184          * are we trying to boot more cores than exist?
 185          */
 186         if (max_cpus > ncores)
 187                 max_cpus = ncores;
 188
 189         /*
 190          * Initialise the present map, which describes the set of CPUs
 191          * actually populated at the present time.
 192          */
 193         for (i = 0; i < max_cpus; i++)
 194                 cpu_set(i, cpu_present_map);
 195
 196         /*
 197          * Do we need any more CPUs? If so, then let them know where
 198          * to start. Note that, on modern versions of MILO, the "poke"
 199          * doesn't actually do anything until each individual core is
 200          * sent a soft interrupt to get it out of WFI
 201          */
 202         if (max_cpus > 1)
 203                 poke_milo();
 204 }