arch/arm/mach-vexpress/platsmp.c

   1 /*
   2  *  linux/arch/arm/mach-vexpress/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/errno.h>
  13 #include <linux/delay.h>
  14 #include <linux/device.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/smp.h>
  17 #include <linux/io.h>
  18
  19 #include <asm/cacheflush.h>
  20 #include <asm/smp_scu.h>
  21 #include <asm/unified.h>
  22
  23 #include <mach/ct-ca9x4.h>
  24 #include <mach/motherboard.h>
  25 #define V2M_PA_CS7 0x10000000
  26
  27 #include "core.h"
  28
  29 extern void vexpress_secondary_startup(void);
  30
  31 /*
  32  * control for which core is the next to come out of the secondary
  33  * boot "holding pen"
  34  */
  35 volatile int __cpuinitdata pen_release = -1;
  36
  37 /*
  38  * Write pen_release in a way that is guaranteed to be visible to all
  39  * observers, irrespective of whether they're taking part in coherency
  40  * or not.  This is necessary for the hotplug code to work reliably.
  41  */
  42 static void write_pen_release(int val)
  43 {
  44         pen_release = val;
  45         smp_wmb();
  46         __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
  47         outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
  48 }
  49
  50 static void __iomem *scu_base_addr(void)
  51 {
  52         return MMIO_P2V(A9_MPCORE_SCU);
  53 }
  54
  55 static DEFINE_SPINLOCK(boot_lock);
  56
  57 void __cpuinit platform_secondary_init(unsigned int cpu)
  58 {
  59         /*
  60          * if any interrupts are already enabled for the primary
  61          * core (e.g. timer irq), then they will not have been enabled
  62          * for us: do so
  63          */
  64         gic_secondary_init(0);
  65
  66         /*
  67          * let the primary processor know we're out of the
  68          * pen, then head off into the C entry point
  69          */
  70         write_pen_release(-1);
  71
  72         /*
  73          * Synchronise with the boot thread.
  74          */
  75         spin_lock(&boot_lock);
  76         spin_unlock(&boot_lock);
  77 }
  78
  79 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  80 {
  81         unsigned long timeout;
  82
  83         /*
  84          * Set synchronisation state between this boot processor
  85          * and the secondary one
  86          */
  87         spin_lock(&boot_lock);
  88
  89         /*
  90          * This is really belt and braces; we hold unintended secondary
  91          * CPUs in the holding pen until we're ready for them.  However,
  92          * since we haven't sent them a soft interrupt, they shouldn't
  93          * be there.
  94          */
  95         write_pen_release(cpu);
  96
  97         /*
  98          * Send the secondary CPU a soft interrupt, thereby causing
  99          * the boot monitor to read the system wide flags register,
 100          * and branch to the address found there.
 101          */
 102         smp_cross_call(cpumask_of(cpu), 1);
 103
 104         timeout = jiffies + (1 * HZ);
 105         while (time_before(jiffies, timeout)) {
 106                 smp_rmb();
 107                 if (pen_release == -1)
 108                         break;
 109
 110                 udelay(10);
 111         }
 112
 113         /*
 114          * now the secondary core is starting up let it run its
 115          * calibrations, then wait for it to finish
 116          */
 117         spin_unlock(&boot_lock);
 118
 119         return pen_release != -1 ? -ENOSYS : 0;
 120 }
 121
 122 /*
 123  * Initialise the CPU possible map early - this describes the CPUs
 124  * which may be present or become present in the system.
 125  */
 126 void __init smp_init_cpus(void)
 127 {
 128         void __iomem *scu_base = scu_base_addr();
 129         unsigned int i, ncores;
 130
 131         ncores = scu_base ? scu_get_core_count(scu_base) : 1;
 132
 133         /* sanity check */
 134         if (ncores > NR_CPUS) {
 135                 printk(KERN_WARNING
 136                        "vexpress: no. of cores (%d) greater than configured "
 137                        "maximum of %d - clipping\n",
 138                        ncores, NR_CPUS);
 139                 ncores = NR_CPUS;
 140         }
 141
 142         for (i = 0; i < ncores; i++)
 143                 set_cpu_possible(i, true);
 144 }
 145
 146 void __init platform_smp_prepare_cpus(unsigned int max_cpus)
 147 {
 148         int i;
 149
 150         /*
 151          * Initialise the present map, which describes the set of CPUs
 152          * actually populated at the present time.
 153          */
 154         for (i = 0; i < max_cpus; i++)
 155                 set_cpu_present(i, true);
 156
 157         scu_enable(scu_base_addr());
 158
 159         /*
 160          * Write the address of secondary startup into the
 161          * system-wide flags register. The boot monitor waits
 162          * until it receives a soft interrupt, and then the
 163          * secondary CPU branches to this address.
 164          */
 165         writel(~0, MMIO_P2V(V2M_SYS_FLAGSCLR));
 166         writel(BSYM(virt_to_phys(vexpress_secondary_startup)),
 167                 MMIO_P2V(V2M_SYS_FLAGSSET));
 168 }