linux/arch/arm/mach-shmobile/platsmp-scu.c
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   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
  18static phys_addr_t shmobile_scu_base_phys;
  19static void __iomem *shmobile_scu_base;
  20
  21static 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
  29void __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
  48void 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
  63static 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
  73int 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
  91