arch/arm/mach-prima2/platsmp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * plat smp support for CSR Marco dual-core SMP SoCs
   4  *
   5  * Copyright (c) 2012 Cambridge Silicon Radio Limited, a CSR plc group company.
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/smp.h>
  10 #include <linux/delay.h>
  11 #include <linux/of.h>
  12 #include <linux/of_address.h>
  13 #include <asm/page.h>
  14 #include <asm/mach/map.h>
  15 #include <asm/smp_plat.h>
  16 #include <asm/smp_scu.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/cputype.h>
  19
  20 #include "common.h"
  21
  22 static void __iomem *clk_base;
  23
  24 static DEFINE_SPINLOCK(boot_lock);
  25
  26 /* XXX prima2_pen_release is cargo culted code - DO NOT COPY XXX */
  27 volatile int prima2_pen_release = -1;
  28
  29 static void sirfsoc_secondary_init(unsigned int cpu)
  30 {
  31         /*
  32          * let the primary processor know we're out of the
  33          * pen, then head off into the C entry point
  34          */
  35         prima2_pen_release = -1;
  36         smp_wmb();
  37
  38         /*
  39          * Synchronise with the boot thread.
  40          */
  41         spin_lock(&boot_lock);
  42         spin_unlock(&boot_lock);
  43 }
  44
  45 static const struct of_device_id clk_ids[]  = {
  46         { .compatible = "sirf,atlas7-clkc" },
  47         {},
  48 };
  49
  50 static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle)
  51 {
  52         unsigned long timeout;
  53         struct device_node *np;
  54
  55         np = of_find_matching_node(NULL, clk_ids);
  56         if (!np)
  57                 return -ENODEV;
  58
  59         clk_base = of_iomap(np, 0);
  60         if (!clk_base)
  61                 return -ENOMEM;
  62
  63         /*
  64          * write the address of secondary startup into the clkc register
  65          * at offset 0x2bC, then write the magic number 0x3CAF5D62 to the
  66          * clkc register at offset 0x2b8, which is what boot rom code is
  67          * waiting for. This would wake up the secondary core from WFE
  68          */
  69 #define SIRFSOC_CPU1_JUMPADDR_OFFSET 0x2bc
  70         __raw_writel(__pa_symbol(sirfsoc_secondary_startup),
  71                 clk_base + SIRFSOC_CPU1_JUMPADDR_OFFSET);
  72
  73 #define SIRFSOC_CPU1_WAKEMAGIC_OFFSET 0x2b8
  74         __raw_writel(0x3CAF5D62,
  75                 clk_base + SIRFSOC_CPU1_WAKEMAGIC_OFFSET);
  76
  77         /* make sure write buffer is drained */
  78         mb();
  79
  80         spin_lock(&boot_lock);
  81
  82         /*
  83          * The secondary processor is waiting to be released from
  84          * the holding pen - release it, then wait for it to flag
  85          * that it has been released by resetting prima2_pen_release.
  86          *
  87          * Note that "prima2_pen_release" is the hardware CPU ID, whereas
  88          * "cpu" is Linux's internal ID.
  89          */
  90         prima2_pen_release = cpu_logical_map(cpu);
  91         sync_cache_w(&prima2_pen_release);
  92
  93         /*
  94          * Send the secondary CPU SEV, thereby causing the boot monitor to read
  95          * the JUMPADDR and WAKEMAGIC, and branch to the address found there.
  96          */
  97         dsb_sev();
  98
  99         timeout = jiffies + (1 * HZ);
 100         while (time_before(jiffies, timeout)) {
 101                 smp_rmb();
 102                 if (prima2_pen_release == -1)
 103                         break;
 104
 105                 udelay(10);
 106         }
 107
 108         /*
 109          * now the secondary core is starting up let it run its
 110          * calibrations, then wait for it to finish
 111          */
 112         spin_unlock(&boot_lock);
 113
 114         return prima2_pen_release != -1 ? -ENOSYS : 0;
 115 }
 116
 117 const struct smp_operations sirfsoc_smp_ops __initconst = {
 118         .smp_secondary_init     = sirfsoc_secondary_init,
 119         .smp_boot_secondary     = sirfsoc_boot_secondary,
 120 #ifdef CONFIG_HOTPLUG_CPU
 121         .cpu_die                = sirfsoc_cpu_die,
 122 #endif
 123 };