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