arch/arm/mach-shmobile/platsmp-scu.c

   1 /*
   2  * SMP support for SoCs with SCU covered by mach-shmobile
   3  *
   4  * Copyright (C) 2013  Magnus Damm
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/cpu.h>
  11 #include <linux/delay.h>
  12 #include <linux/init.h>
  13 #include <linux/io.h>
  14 #include <linux/smp.h>
  15 #include <asm/cacheflush.h>
  16 #include <asm/smp_plat.h>
  17 #include <asm/smp_scu.h>
  18 #include "common.h"
  19
  20
  21 void __iomem *shmobile_scu_base;
  22
  23 static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
  24                                           unsigned long action, void *hcpu)
  25 {
  26         unsigned int cpu = (long)hcpu;
  27
  28         switch (action) {
  29         case CPU_UP_PREPARE:
  30                 /* For this particular CPU register SCU SMP boot vector */
  31                 shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
  32                                   (unsigned long)shmobile_scu_base);
  33                 break;
  34         };
  35
  36         return NOTIFY_OK;
  37 }
  38
  39 static struct notifier_block shmobile_smp_scu_notifier = {
  40         .notifier_call = shmobile_smp_scu_notifier_call,
  41 };
  42
  43 void __init shmobile_smp_scu_prepare_cpus(unsigned int max_cpus)
  44 {
  45         /* install boot code shared by all CPUs */
  46         shmobile_boot_fn = virt_to_phys(shmobile_smp_boot);
  47
  48         /* enable SCU and cache coherency on booting CPU */
  49         scu_enable(shmobile_scu_base);
  50         scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
  51
  52         /* Use CPU notifier for reset vector control */
  53         register_cpu_notifier(&shmobile_smp_scu_notifier);
  54 }
  55
  56 #ifdef CONFIG_HOTPLUG_CPU
  57 void shmobile_smp_scu_cpu_die(unsigned int cpu)
  58 {
  59         /* For this particular CPU deregister boot vector */
  60         shmobile_smp_hook(cpu, 0, 0);
  61
  62         dsb();
  63         flush_cache_all();
  64
  65         /* disable cache coherency */
  66         scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
  67
  68         /* jump to shared mach-shmobile sleep / reset code */
  69         shmobile_smp_sleep();
  70 }
  71
  72 static int shmobile_smp_scu_psr_core_disabled(int cpu)
  73 {
  74         unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
  75
  76         if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
  77                 return 1;
  78
  79         return 0;
  80 }
  81
  82 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
  83 {
  84         int k;
  85
  86         /* this function is running on another CPU than the offline target,
  87          * here we need wait for shutdown code in platform_cpu_die() to
  88          * finish before asking SoC-specific code to power off the CPU core.
  89          */
  90         for (k = 0; k < 1000; k++) {
  91                 if (shmobile_smp_scu_psr_core_disabled(cpu))
  92                         return 1;
  93
  94                 mdelay(1);
  95         }
  96
  97         return 0;
  98 }
  99 #endif