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/jiffies.h>
  16 #include <linux/smp.h>
  17 #include <linux/io.h>
  18
  19 #include <asm/cacheflush.h>
  20 #include <mach/hardware.h>
  21 #include <asm/mach-types.h>
  22 #include <asm/localtimer.h>
  23 #include <asm/unified.h>
  24
  25 #include <mach/board-eb.h>
  26 #include <mach/board-pb11mp.h>
  27 #include <mach/board-pbx.h>
  28 #include <asm/smp_scu.h>
  29
  30 #include "core.h"
  31
  32 extern void realview_secondary_startup(void);
  33
  34 /*
  35  * control for which core is the next to come out of the secondary
  36  * boot "holding pen"
  37  */
  38 volatile int __cpuinitdata pen_release = -1;
  39
  40 static void __iomem *scu_base_addr(void)
  41 {
  42         if (machine_is_realview_eb_mp())
  43                 return __io_address(REALVIEW_EB11MP_SCU_BASE);
  44         else if (machine_is_realview_pb11mp())
  45                 return __io_address(REALVIEW_TC11MP_SCU_BASE);
  46         else if (machine_is_realview_pbx() &&
  47                  (core_tile_pbx11mp() || core_tile_pbxa9mp()))
  48                 return __io_address(REALVIEW_PBX_TILE_SCU_BASE);
  49         else
  50                 return (void __iomem *)0;
  51 }
  52
  53 static inline unsigned int get_core_count(void)
  54 {
  55         void __iomem *scu_base = scu_base_addr();
  56         if (scu_base)
  57                 return scu_get_core_count(scu_base);
  58         return 1;
  59 }
  60
  61 static DEFINE_SPINLOCK(boot_lock);
  62
  63 void __cpuinit platform_secondary_init(unsigned int cpu)
  64 {
  65         trace_hardirqs_off();
  66
  67         /*
  68          * if any interrupts are already enabled for the primary
  69          * core (e.g. timer irq), then they will not have been enabled
  70          * for us: do so
  71          */
  72         gic_cpu_init(0, gic_cpu_base_addr);
  73
  74         /*
  75          * let the primary processor know we're out of the
  76          * pen, then head off into the C entry point
  77          */
  78         pen_release = -1;
  79         smp_wmb();
  80
  81         /*
  82          * Synchronise with the boot thread.
  83          */
  84         spin_lock(&boot_lock);
  85         spin_unlock(&boot_lock);
  86 }
  87
  88 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  89 {
  90         unsigned long timeout;
  91
  92         /*
  93          * set synchronisation state between this boot processor
  94          * and the secondary one
  95          */
  96         spin_lock(&boot_lock);
  97
  98         /*
  99          * The secondary processor is waiting to be released from
 100          * the holding pen - release it, then wait for it to flag
 101          * that it has been released by resetting pen_release.
 102          *
 103          * Note that "pen_release" is the hardware CPU ID, whereas
 104          * "cpu" is Linux's internal ID.
 105          */
 106         pen_release = cpu;
 107         flush_cache_all();
 108
 109         /*
 110          * XXX
 111          *
 112          * This is a later addition to the booting protocol: the
 113          * bootMonitor now puts secondary cores into WFI, so
 114          * poke_milo() no longer gets the cores moving; we need
 115          * to send a soft interrupt to wake the secondary core.
 116          * Use smp_cross_call() for this, since there's little
 117          * point duplicating the code here
 118          */
 119         smp_cross_call(cpumask_of(cpu));
 120
 121         timeout = jiffies + (1 * HZ);
 122         while (time_before(jiffies, timeout)) {
 123                 smp_rmb();
 124                 if (pen_release == -1)
 125                         break;
 126
 127                 udelay(10);
 128         }
 129
 130         /*
 131          * now the secondary core is starting up let it run its
 132          * calibrations, then wait for it to finish
 133          */
 134         spin_unlock(&boot_lock);
 135
 136         return pen_release != -1 ? -ENOSYS : 0;
 137 }
 138
 139 static void __init poke_milo(void)
 140 {
 141         /* nobody is to be released from the pen yet */
 142         pen_release = -1;
 143
 144         /*
 145          * Write the address of secondary startup into the system-wide flags
 146          * register. The BootMonitor waits for this register to become
 147          * non-zero.
 148          */
 149         __raw_writel(BSYM(virt_to_phys(realview_secondary_startup)),
 150                      __io_address(REALVIEW_SYS_FLAGSSET));
 151
 152         mb();
 153 }
 154
 155 /*
 156  * Initialise the CPU possible map early - this describes the CPUs
 157  * which may be present or become present in the system.
 158  */
 159 void __init smp_init_cpus(void)
 160 {
 161         unsigned int i, ncores = get_core_count();
 162
 163         for (i = 0; i < ncores; i++)
 164                 set_cpu_possible(i, true);
 165 }
 166
 167 void __init smp_prepare_cpus(unsigned int max_cpus)
 168 {
 169         unsigned int ncores = get_core_count();
 170         unsigned int cpu = smp_processor_id();
 171         int i;
 172
 173         /* sanity check */
 174         if (ncores == 0) {
 175                 printk(KERN_ERR
 176                        "Realview: strange CM count of 0? Default to 1\n");
 177
 178                 ncores = 1;
 179         }
 180
 181         if (ncores > NR_CPUS) {
 182                 printk(KERN_WARNING
 183                        "Realview: no. of cores (%d) greater than configured "
 184                        "maximum of %d - clipping\n",
 185                        ncores, NR_CPUS);
 186                 ncores = NR_CPUS;
 187         }
 188
 189         smp_store_cpu_info(cpu);
 190
 191         /*
 192          * are we trying to boot more cores than exist?
 193          */
 194         if (max_cpus > ncores)
 195                 max_cpus = ncores;
 196
 197         /*
 198          * Initialise the present map, which describes the set of CPUs
 199          * actually populated at the present time.
 200          */
 201         for (i = 0; i < max_cpus; i++)
 202                 set_cpu_present(i, true);
 203
 204         /*
 205          * Initialise the SCU if there are more than one CPU and let
 206          * them know where to start. Note that, on modern versions of
 207          * MILO, the "poke" doesn't actually do anything until each
 208          * individual core is sent a soft interrupt to get it out of
 209          * WFI
 210          */
 211         if (max_cpus > 1) {
 212                 /*
 213                  * Enable the local timer or broadcast device for the
 214                  * boot CPU, but only if we have more than one CPU.
 215                  */
 216                 percpu_timer_setup();
 217
 218                 scu_enable(scu_base_addr());
 219                 poke_milo();
 220         }
 221 }