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 static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
  21                                           unsigned long action, void *hcpu)
  22 {
  23         unsigned int cpu = (long)hcpu;
  24
  25         switch (action) {
  26         case CPU_UP_PREPARE:
  27                 /* For this particular CPU register SCU SMP boot vector */
  28                 shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
  29                                   (unsigned long)shmobile_scu_base);
  30                 break;
  31         };
  32
  33         return NOTIFY_OK;
  34 }
  35
  36 static struct notifier_block shmobile_smp_scu_notifier = {
  37         .notifier_call = shmobile_smp_scu_notifier_call,
  38 };
  39
  40 void __init shmobile_smp_scu_prepare_cpus(unsigned int max_cpus)
  41 {
  42         /* install boot code shared by all CPUs */
  43         shmobile_boot_fn = virt_to_phys(shmobile_smp_boot);
  44         shmobile_boot_arg = MPIDR_HWID_BITMASK;
  45
  46         /* enable SCU and cache coherency on booting CPU */
  47         scu_enable(shmobile_scu_base);
  48         scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
  49
  50         /* Use CPU notifier for reset vector control */
  51         register_cpu_notifier(&shmobile_smp_scu_notifier);
  52 }
  53
  54 #ifdef CONFIG_HOTPLUG_CPU
  55 void shmobile_smp_scu_cpu_die(unsigned int cpu)
  56 {
  57         /* For this particular CPU deregister boot vector */
  58         shmobile_smp_hook(cpu, 0, 0);
  59
  60         dsb();
  61         flush_cache_all();
  62
  63         /* disable cache coherency */
  64         scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
  65
  66         /* jump to shared mach-shmobile sleep / reset code */
  67         shmobile_smp_sleep();
  68 }
  69
  70 static int shmobile_smp_scu_psr_core_disabled(int cpu)
  71 {
  72         unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
  73
  74         if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
  75                 return 1;
  76
  77         return 0;
  78 }
  79
  80 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
  81 {
  82         int k;
  83
  84         /* this function is running on another CPU than the offline target,
  85          * here we need wait for shutdown code in platform_cpu_die() to
  86          * finish before asking SoC-specific code to power off the CPU core.
  87          */
  88         for (k = 0; k < 1000; k++) {
  89                 if (shmobile_smp_scu_psr_core_disabled(cpu))
  90                         return 1;
  91
  92                 mdelay(1);
  93         }
  94
  95         return 0;
  96 }
  97 #endif