LXR linux/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
  23static void __iomem *clk_base;
  24
  25static DEFINE_SPINLOCK(boot_lock);
  26
  27/* XXX prima2_pen_release is cargo culted code - DO NOT COPY XXX */
  28volatile int prima2_pen_release = -1;
  29
  30static void sirfsoc_secondary_init(unsigned int cpu)
  31{
  32        /*
  33         * let the primary processor know we're out of the
  34         * pen, then head off into the C entry point
  35         */
  36        prima2_pen_release = -1;
  37        smp_wmb();
  38
  39        /*
  40         * Synchronise with the boot thread.
  41         */
  42        spin_lock(&boot_lock);
  43        spin_unlock(&boot_lock);
  44}
  45
  46static const struct of_device_id clk_ids[]  = {
  47        { .compatible = "sirf,atlas7-clkc" },
  48        {},
  49};
  50
  51static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle)
  52{
  53        unsigned long timeout;
  54        struct device_node *np;
  55
  56        np = of_find_matching_node(NULL, clk_ids);
  57        if (!np)
  58                return -ENODEV;
  59
  60        clk_base = of_iomap(np, 0);
  61        if (!clk_base)
  62                return -ENOMEM;
  63
  64        /*
  65         * write the address of secondary startup into the clkc register
  66         * at offset 0x2bC, then write the magic number 0x3CAF5D62 to the
  67         * clkc register at offset 0x2b8, which is what boot rom code is
  68         * waiting for. This would wake up the secondary core from WFE
  69         */
  70#define SIRFSOC_CPU1_JUMPADDR_OFFSET 0x2bc
  71        __raw_writel(__pa_symbol(sirfsoc_secondary_startup),
  72                clk_base + SIRFSOC_CPU1_JUMPADDR_OFFSET);
  73
  74#define SIRFSOC_CPU1_WAKEMAGIC_OFFSET 0x2b8
  75        __raw_writel(0x3CAF5D62,
  76                clk_base + SIRFSOC_CPU1_WAKEMAGIC_OFFSET);
  77
  78        /* make sure write buffer is drained */
  79        mb();
  80
  81        spin_lock(&boot_lock);
  82
  83        /*
  84         * The secondary processor is waiting to be released from
  85         * the holding pen - release it, then wait for it to flag
  86         * that it has been released by resetting prima2_pen_release.
  87         *
  88         * Note that "prima2_pen_release" is the hardware CPU ID, whereas
  89         * "cpu" is Linux's internal ID.
  90         */
  91        prima2_pen_release = cpu_logical_map(cpu);
  92        sync_cache_w(&prima2_pen_release);
  93
  94        /*
  95         * Send the secondary CPU SEV, thereby causing the boot monitor to read
  96         * the JUMPADDR and WAKEMAGIC, and branch to the address found there.
  97         */
  98        dsb_sev();
  99
 100        timeout = jiffies + (1 * HZ);
 101        while (time_before(jiffies, timeout)) {
 102                smp_rmb();
 103                if (prima2_pen_release == -1)
 104                        break;
 105
 106                udelay(10);
 107        }
 108
 109        /*
 110         * now the secondary core is starting up let it run its
 111         * calibrations, then wait for it to finish
 112         */
 113        spin_unlock(&boot_lock);
 114
 115        return prima2_pen_release != -1 ? -ENOSYS : 0;
 116}
 117
 118const struct smp_operations sirfsoc_smp_ops __initconst = {
 119        .smp_secondary_init     = sirfsoc_secondary_init,
 120        .smp_boot_secondary     = sirfsoc_boot_secondary,
 121#ifdef CONFIG_HOTPLUG_CPU
 122        .cpu_die                = sirfsoc_cpu_die,
 123#endif
 124};
 125