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(__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
  63         /*
  64          * Synchronise with the boot thread.
  65          */
  66         spin_lock(&boot_lock);
  67         spin_unlock(&boot_lock);
  68 }
  69
  70 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  71 {
  72         unsigned long timeout;
  73
  74         /*
  75          * set synchronisation state between this boot processor
  76          * and the secondary one
  77          */
  78         spin_lock(&boot_lock);
  79
  80         /*
  81          * The secondary processor is waiting to be released from
  82          * the holding pen - release it, then wait for it to flag
  83          * that it has been released by resetting pen_release.
  84          *
  85          * Note that "pen_release" is the hardware CPU ID, whereas
  86          * "cpu" is Linux's internal ID.
  87          */
  88         pen_release = cpu;
  89         flush_cache_all();
  90
  91         /*
  92          * XXX
  93          *
  94          * This is a later addition to the booting protocol: the
  95          * bootMonitor now puts secondary cores into WFI, so
  96          * poke_milo() no longer gets the cores moving; we need
  97          * to send a soft interrupt to wake the secondary core.
  98          * Use smp_cross_call() for this, since there's little
  99          * point duplicating the code here
 100          */
 101         smp_cross_call(cpumask_of_cpu(cpu));
 102
 103         timeout = jiffies + (1 * HZ);
 104         while (time_before(jiffies, timeout)) {
 105                 if (pen_release == -1)
 106                         break;
 107
 108                 udelay(10);
 109         }
 110
 111         /*
 112          * now the secondary core is starting up let it run its
 113          * calibrations, then wait for it to finish
 114          */
 115         spin_unlock(&boot_lock);
 116
 117         return pen_release != -1 ? -ENOSYS : 0;
 118 }
 119
 120 static void __init poke_milo(void)
 121 {
 122         extern void secondary_startup(void);
 123
 124         /* nobody is to be released from the pen yet */
 125         pen_release = -1;
 126
 127         /*
 128          * write the address of secondary startup into the system-wide
 129          * flags register, then clear the bottom two bits, which is what
 130          * BootMonitor is waiting for
 131          */
 132 #if 1
 133 #define REALVIEW_SYS_FLAGSS_OFFSET 0x30
 134         __raw_writel(virt_to_phys(realview_secondary_startup),
 135                      __io_address(REALVIEW_SYS_BASE) +
 136                      REALVIEW_SYS_FLAGSS_OFFSET);
 137 #define REALVIEW_SYS_FLAGSC_OFFSET 0x34
 138         __raw_writel(3,
 139                      __io_address(REALVIEW_SYS_BASE) +
 140                      REALVIEW_SYS_FLAGSC_OFFSET);
 141 #endif
 142
 143         mb();
 144 }
 145
 146 /*
 147  * Initialise the CPU possible map early - this describes the CPUs
 148  * which may be present or become present in the system.
 149  */
 150 void __init smp_init_cpus(void)
 151 {
 152         unsigned int i, ncores = get_core_count();
 153
 154         for (i = 0; i < ncores; i++)
 155                 cpu_set(i, cpu_possible_map);
 156 }
 157
 158 void __init smp_prepare_cpus(unsigned int max_cpus)
 159 {
 160         unsigned int ncores = get_core_count();
 161         unsigned int cpu = smp_processor_id();
 162         int i;
 163
 164         /* sanity check */
 165         if (ncores == 0) {
 166                 printk(KERN_ERR
 167                        "Realview: strange CM count of 0? Default to 1\n");
 168
 169                 ncores = 1;
 170         }
 171
 172         if (ncores > NR_CPUS) {
 173                 printk(KERN_WARNING
 174                        "Realview: no. of cores (%d) greater than configured "
 175                        "maximum of %d - clipping\n",
 176                        ncores, NR_CPUS);
 177                 ncores = NR_CPUS;
 178         }
 179
 180         smp_store_cpu_info(cpu);
 181
 182         /*
 183          * are we trying to boot more cores than exist?
 184          */
 185         if (max_cpus > ncores)
 186                 max_cpus = ncores;
 187
 188         /*
 189          * Enable the local timer for primary CPU
 190          */
 191         local_timer_setup(cpu);
 192
 193         /*
 194          * Initialise the present map, which describes the set of CPUs
 195          * actually populated at the present time.
 196          */
 197         for (i = 0; i < max_cpus; i++)
 198                 cpu_set(i, cpu_present_map);
 199
 200         /*
 201          * Do we need any more CPUs? If so, then let them know where
 202          * to start. Note that, on modern versions of MILO, the "poke"
 203          * doesn't actually do anything until each individual core is
 204          * sent a soft interrupt to get it out of WFI
 205          */
 206         if (max_cpus > 1)
 207                 poke_milo();
 208 }