arch/arm/mach-prima2/platsmp.c

   1 /*
   2  * plat smp support for CSR Marco dual-core SMP SoCs
   3  *
   4  * Copyright (c) 2012 Cambridge Silicon Radio Limited, a CSR plc group company.
   5  *
   6  * Licensed under GPLv2 or later.
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/smp.h>
  11 #include <linux/delay.h>
  12 #include <linux/of.h>
  13 #include <linux/of_address.h>
  14 #include <asm/page.h>
  15 #include <asm/mach/map.h>
  16 #include <asm/smp_plat.h>
  17 #include <asm/smp_scu.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/cputype.h>
  20
  21 #include "common.h"
  22
  23 static void __iomem *clk_base;
  24
  25 static DEFINE_SPINLOCK(boot_lock);
  26
  27 static void sirfsoc_secondary_init(unsigned int cpu)
  28 {
  29         /*
  30          * let the primary processor know we're out of the
  31          * pen, then head off into the C entry point
  32          */
  33         pen_release = -1;
  34         smp_wmb();
  35
  36         /*
  37          * Synchronise with the boot thread.
  38          */
  39         spin_lock(&boot_lock);
  40         spin_unlock(&boot_lock);
  41 }
  42
  43 static const struct of_device_id clk_ids[]  = {
  44         { .compatible = "sirf,atlas7-clkc" },
  45         {},
  46 };
  47
  48 static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle)
  49 {
  50         unsigned long timeout;
  51         struct device_node *np;
  52
  53         np = of_find_matching_node(NULL, clk_ids);
  54         if (!np)
  55                 return -ENODEV;
  56
  57         clk_base = of_iomap(np, 0);
  58         if (!clk_base)
  59                 return -ENOMEM;
  60
  61         /*
  62          * write the address of secondary startup into the clkc register
  63          * at offset 0x2bC, then write the magic number 0x3CAF5D62 to the
  64          * clkc register at offset 0x2b8, which is what boot rom code is
  65          * waiting for. This would wake up the secondary core from WFE
  66          */
  67 #define SIRFSOC_CPU1_JUMPADDR_OFFSET 0x2bc
  68         __raw_writel(virt_to_phys(sirfsoc_secondary_startup),
  69                 clk_base + SIRFSOC_CPU1_JUMPADDR_OFFSET);
  70
  71 #define SIRFSOC_CPU1_WAKEMAGIC_OFFSET 0x2b8
  72         __raw_writel(0x3CAF5D62,
  73                 clk_base + SIRFSOC_CPU1_WAKEMAGIC_OFFSET);
  74
  75         /* make sure write buffer is drained */
  76         mb();
  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_logical_map(cpu);
  89         sync_cache_w(&pen_release);
  90
  91         /*
  92          * Send the secondary CPU SEV, thereby causing the boot monitor to read
  93          * the JUMPADDR and WAKEMAGIC, and branch to the address found there.
  94          */
  95         dsb_sev();
  96
  97         timeout = jiffies + (1 * HZ);
  98         while (time_before(jiffies, timeout)) {
  99                 smp_rmb();
 100                 if (pen_release == -1)
 101                         break;
 102
 103                 udelay(10);
 104         }
 105
 106         /*
 107          * now the secondary core is starting up let it run its
 108          * calibrations, then wait for it to finish
 109          */
 110         spin_unlock(&boot_lock);
 111
 112         return pen_release != -1 ? -ENOSYS : 0;
 113 }
 114
 115 struct smp_operations sirfsoc_smp_ops __initdata = {
 116         .smp_secondary_init     = sirfsoc_secondary_init,
 117         .smp_boot_secondary     = sirfsoc_boot_secondary,
 118 #ifdef CONFIG_HOTPLUG_CPU
 119         .cpu_die                = sirfsoc_cpu_die,
 120 #endif
 121 };