arch/arm/mach-sti/platsmp.c

   1 /*
   2  *  arch/arm/mach-sti/platsmp.c
   3  *
   4  * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
   5  *              http://www.st.com
   6  *
   7  * Cloned from linux/arch/arm/mach-vexpress/platsmp.c
   8  *
   9  *  Copyright (C) 2002 ARM Ltd.
  10  *  All Rights Reserved
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16 #include <linux/init.h>
  17 #include <linux/errno.h>
  18 #include <linux/delay.h>
  19 #include <linux/smp.h>
  20 #include <linux/io.h>
  21 #include <linux/of.h>
  22 #include <linux/of_address.h>
  23 #include <linux/memblock.h>
  24
  25 #include <asm/cacheflush.h>
  26 #include <asm/smp_plat.h>
  27 #include <asm/smp_scu.h>
  28
  29 #include "smp.h"
  30
  31 static void write_pen_release(int val)
  32 {
  33         pen_release = val;
  34         smp_wmb();
  35         sync_cache_w(&pen_release);
  36 }
  37
  38 static DEFINE_SPINLOCK(boot_lock);
  39
  40 static void sti_secondary_init(unsigned int cpu)
  41 {
  42         /*
  43          * let the primary processor know we're out of the
  44          * pen, then head off into the C entry point
  45          */
  46         write_pen_release(-1);
  47
  48         /*
  49          * Synchronise with the boot thread.
  50          */
  51         spin_lock(&boot_lock);
  52         spin_unlock(&boot_lock);
  53 }
  54
  55 static int sti_boot_secondary(unsigned int cpu, struct task_struct *idle)
  56 {
  57         unsigned long timeout;
  58
  59         /*
  60          * set synchronisation state between this boot processor
  61          * and the secondary one
  62          */
  63         spin_lock(&boot_lock);
  64
  65         /*
  66          * The secondary processor is waiting to be released from
  67          * the holding pen - release it, then wait for it to flag
  68          * that it has been released by resetting pen_release.
  69          *
  70          * Note that "pen_release" is the hardware CPU ID, whereas
  71          * "cpu" is Linux's internal ID.
  72          */
  73         write_pen_release(cpu_logical_map(cpu));
  74
  75         /*
  76          * Send the secondary CPU a soft interrupt, thereby causing
  77          * it to jump to the secondary entrypoint.
  78          */
  79         arch_send_wakeup_ipi_mask(cpumask_of(cpu));
  80
  81         timeout = jiffies + (1 * HZ);
  82         while (time_before(jiffies, timeout)) {
  83                 smp_rmb();
  84                 if (pen_release == -1)
  85                         break;
  86
  87                 udelay(10);
  88         }
  89
  90         /*
  91          * now the secondary core is starting up let it run its
  92          * calibrations, then wait for it to finish
  93          */
  94         spin_unlock(&boot_lock);
  95
  96         return pen_release != -1 ? -ENOSYS : 0;
  97 }
  98
  99 static void __init sti_smp_prepare_cpus(unsigned int max_cpus)
 100 {
 101         struct device_node *np;
 102         void __iomem *scu_base;
 103         u32 __iomem *cpu_strt_ptr;
 104         u32 release_phys;
 105         int cpu;
 106         unsigned long entry_pa = __pa_symbol(sti_secondary_startup);
 107
 108         np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
 109
 110         if (np) {
 111                 scu_base = of_iomap(np, 0);
 112                 scu_enable(scu_base);
 113                 of_node_put(np);
 114         }
 115
 116         if (max_cpus <= 1)
 117                 return;
 118
 119         for_each_possible_cpu(cpu) {
 120
 121                 np = of_get_cpu_node(cpu, NULL);
 122
 123                 if (!np)
 124                         continue;
 125
 126                 if (of_property_read_u32(np, "cpu-release-addr",
 127                                                 &release_phys)) {
 128                         pr_err("CPU %d: missing or invalid cpu-release-addr "
 129                                 "property\n", cpu);
 130                         continue;
 131                 }
 132
 133                 /*
 134                  * holding pen is usually configured in SBC DMEM but can also be
 135                  * in RAM.
 136                  */
 137
 138                 if (!memblock_is_memory(release_phys))
 139                         cpu_strt_ptr =
 140                                 ioremap(release_phys, sizeof(release_phys));
 141                 else
 142                         cpu_strt_ptr =
 143                                 (u32 __iomem *)phys_to_virt(release_phys);
 144
 145                 __raw_writel(entry_pa, cpu_strt_ptr);
 146
 147                 /*
 148                  * wmb so that data is actually written
 149                  * before cache flush is done
 150                  */
 151                 smp_wmb();
 152                 sync_cache_w(cpu_strt_ptr);
 153
 154                 if (!memblock_is_memory(release_phys))
 155                         iounmap(cpu_strt_ptr);
 156         }
 157 }
 158
 159 const struct smp_operations sti_smp_ops __initconst = {
 160         .smp_prepare_cpus       = sti_smp_prepare_cpus,
 161         .smp_secondary_init     = sti_secondary_init,
 162         .smp_boot_secondary     = sti_boot_secondary,
 163 };