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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * SMP support for SoCs with SCU covered by mach-shmobile
   4  *
   5  * Copyright (C) 2013  Magnus Damm
   6  */
   7 #include <linux/cpu.h>
   8 #include <linux/delay.h>
   9 #include <linux/init.h>
  10 #include <linux/io.h>
  11 #include <linux/smp.h>
  12 #include <asm/cacheflush.h>
  13 #include <asm/smp_plat.h>
  14 #include <asm/smp_scu.h>
  15 #include "common.h"
  16
  17
  18 static phys_addr_t shmobile_scu_base_phys;
  19 static void __iomem *shmobile_scu_base;
  20
  21 static int shmobile_scu_cpu_prepare(unsigned int cpu)
  22 {
  23         /* For this particular CPU register SCU SMP boot vector */
  24         shmobile_smp_hook(cpu, __pa_symbol(shmobile_boot_scu),
  25                           shmobile_scu_base_phys);
  26         return 0;
  27 }
  28
  29 void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
  30                                           unsigned int max_cpus)
  31 {
  32         /* install boot code shared by all CPUs */
  33         shmobile_boot_fn = __pa_symbol(shmobile_smp_boot);
  34
  35         /* enable SCU and cache coherency on booting CPU */
  36         shmobile_scu_base_phys = scu_base_phys;
  37         shmobile_scu_base = ioremap(scu_base_phys, PAGE_SIZE);
  38         scu_enable(shmobile_scu_base);
  39         scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
  40
  41         /* Use CPU notifier for reset vector control */
  42         cpuhp_setup_state_nocalls(CPUHP_ARM_SHMOBILE_SCU_PREPARE,
  43                                   "arm/shmobile-scu:prepare",
  44                                   shmobile_scu_cpu_prepare, NULL);
  45 }
  46
  47 #ifdef CONFIG_HOTPLUG_CPU
  48 void shmobile_smp_scu_cpu_die(unsigned int cpu)
  49 {
  50         /* For this particular CPU deregister boot vector */
  51         shmobile_smp_hook(cpu, 0, 0);
  52
  53         dsb();
  54         flush_cache_all();
  55
  56         /* disable cache coherency */
  57         scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
  58
  59         /* jump to shared mach-shmobile sleep / reset code */
  60         shmobile_smp_sleep();
  61 }
  62
  63 static int shmobile_smp_scu_psr_core_disabled(int cpu)
  64 {
  65         unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
  66
  67         if ((readl(shmobile_scu_base + 8) & mask) == mask)
  68                 return 1;
  69
  70         return 0;
  71 }
  72
  73 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
  74 {
  75         int k;
  76
  77         /* this function is running on another CPU than the offline target,
  78          * here we need wait for shutdown code in platform_cpu_die() to
  79          * finish before asking SoC-specific code to power off the CPU core.
  80          */
  81         for (k = 0; k < 1000; k++) {
  82                 if (shmobile_smp_scu_psr_core_disabled(cpu))
  83                         return 1;
  84
  85                 mdelay(1);
  86         }
  87
  88         return 0;
  89 }
  90 #endif