arch/arm/mach-realview/platsmp.c

   1 /*
   2  *  linux/arch/arm/mach-realview/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/smp.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/hardware/arm_scu.h>
  19 #include <asm/hardware.h>
  20 #include <asm/io.h>
  21
  22 extern void realview_secondary_startup(void);
  23
  24 /*
  25  * control for which core is the next to come out of the secondary
  26  * boot "holding pen"
  27  */
  28 volatile int __cpuinitdata pen_release = -1;
  29
  30 static unsigned int __init get_core_count(void)
  31 {
  32         unsigned int ncores;
  33
  34         ncores = __raw_readl(__io_address(REALVIEW_MPCORE_SCU_BASE) + SCU_CONFIG);
  35
  36         return (ncores & 0x03) + 1;
  37 }
  38
  39 static DEFINE_SPINLOCK(boot_lock);
  40
  41 void __cpuinit platform_secondary_init(unsigned int cpu)
  42 {
  43         /*
  44          * the primary core may have used a "cross call" soft interrupt
  45          * to get this processor out of WFI in the BootMonitor - make
  46          * sure that we are no longer being sent this soft interrupt
  47          */
  48         smp_cross_call_done(cpumask_of_cpu(cpu));
  49
  50         /*
  51          * if any interrupts are already enabled for the primary
  52          * core (e.g. timer irq), then they will not have been enabled
  53          * for us: do so
  54          */
  55         gic_cpu_init(0, __io_address(REALVIEW_GIC_CPU_BASE));
  56
  57         /*
  58          * let the primary processor know we're out of the
  59          * pen, then head off into the C entry point
  60          */
  61         pen_release = -1;
  62         smp_wmb();
  63
  64         /*
  65          * Synchronise with the boot thread.
  66          */
  67         spin_lock(&boot_lock);
  68         spin_unlock(&boot_lock);
  69 }
  70
  71 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  72 {
  73         unsigned long timeout;
  74
  75         /*
  76          * set synchronisation state between this boot processor
  77          * and the secondary one
  78          */
  79         spin_lock(&boot_lock);
  80
  81         /*
  82          * The secondary processor is waiting to be released from
  83          * the holding pen - release it, then wait for it to flag
  84          * that it has been released by resetting pen_release.
  85          *
  86          * Note that "pen_release" is the hardware CPU ID, whereas
  87          * "cpu" is Linux's internal ID.
  88          */
  89         pen_release = cpu;
  90         flush_cache_all();
  91
  92         /*
  93          * XXX
  94          *
  95          * This is a later addition to the booting protocol: the
  96          * bootMonitor now puts secondary cores into WFI, so
  97          * poke_milo() no longer gets the cores moving; we need
  98          * to send a soft interrupt to wake the secondary core.
  99          * Use smp_cross_call() for this, since there's little
 100          * point duplicating the code here
 101          */
 102         smp_cross_call(cpumask_of_cpu(cpu));
 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 static void __init poke_milo(void)
 123 {
 124         extern void secondary_startup(void);
 125
 126         /* nobody is to be released from the pen yet */
 127         pen_release = -1;
 128
 129         /*
 130          * write the address of secondary startup into the system-wide
 131          * flags register, then clear the bottom two bits, which is what
 132          * BootMonitor is waiting for
 133          */
 134 #if 1
 135 #define REALVIEW_SYS_FLAGSS_OFFSET 0x30
 136         __raw_writel(virt_to_phys(realview_secondary_startup),
 137                      __io_address(REALVIEW_SYS_BASE) +
 138                      REALVIEW_SYS_FLAGSS_OFFSET);
 139 #define REALVIEW_SYS_FLAGSC_OFFSET 0x34
 140         __raw_writel(3,
 141                      __io_address(REALVIEW_SYS_BASE) +
 142                      REALVIEW_SYS_FLAGSC_OFFSET);
 143 #endif
 144
 145         mb();
 146 }
 147
 148 /*
 149  * Initialise the CPU possible map early - this describes the CPUs
 150  * which may be present or become present in the system.
 151  */
 152 void __init smp_init_cpus(void)
 153 {
 154         unsigned int i, ncores = get_core_count();
 155
 156         for (i = 0; i < ncores; i++)
 157                 cpu_set(i, cpu_possible_map);
 158 }
 159
 160 void __init smp_prepare_cpus(unsigned int max_cpus)
 161 {
 162         unsigned int ncores = get_core_count();
 163         unsigned int cpu = smp_processor_id();
 164         int i;
 165
 166         /* sanity check */
 167         if (ncores == 0) {
 168                 printk(KERN_ERR
 169                        "Realview: strange CM count of 0? Default to 1\n");
 170
 171                 ncores = 1;
 172         }
 173
 174         if (ncores > NR_CPUS) {
 175                 printk(KERN_WARNING
 176                        "Realview: no. of cores (%d) greater than configured "
 177                        "maximum of %d - clipping\n",
 178                        ncores, NR_CPUS);
 179                 ncores = NR_CPUS;
 180         }
 181
 182         smp_store_cpu_info(cpu);
 183
 184         /*
 185          * are we trying to boot more cores than exist?
 186          */
 187         if (max_cpus > ncores)
 188                 max_cpus = ncores;
 189
 190         /*
 191          * Enable the local timer for primary CPU
 192          */
 193         local_timer_setup(cpu);
 194
 195         /*
 196          * Initialise the present map, which describes the set of CPUs
 197          * actually populated at the present time.
 198          */
 199         for (i = 0; i < max_cpus; i++)
 200                 cpu_set(i, cpu_present_map);
 201
 202         /*
 203          * Do we need any more CPUs? If so, then let them know where
 204          * to start. Note that, on modern versions of MILO, the "poke"
 205          * doesn't actually do anything until each individual core is
 206          * sent a soft interrupt to get it out of WFI
 207          */
 208         if (max_cpus > 1)
 209                 poke_milo();
 210 }