LXR linux/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
  21static phys_addr_t shmobile_scu_base_phys;
  22static void __iomem *shmobile_scu_base;
  23
  24static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
  25                                          unsigned long action, void *hcpu)
  26{
  27        unsigned int cpu = (long)hcpu;
  28
  29        switch (action) {
  30        case CPU_UP_PREPARE:
  31                /* For this particular CPU register SCU SMP boot vector */
  32                shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
  33                                  shmobile_scu_base_phys);
  34                break;
  35        };
  36
  37        return NOTIFY_OK;
  38}
  39
  40static struct notifier_block shmobile_smp_scu_notifier = {
  41        .notifier_call = shmobile_smp_scu_notifier_call,
  42};
  43
  44void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
  45                                          unsigned int max_cpus)
  46{
  47        /* install boot code shared by all CPUs */
  48        shmobile_boot_fn = virt_to_phys(shmobile_smp_boot);
  49
  50        /* enable SCU and cache coherency on booting CPU */
  51        shmobile_scu_base_phys = scu_base_phys;
  52        shmobile_scu_base = ioremap(scu_base_phys, PAGE_SIZE);
  53        scu_enable(shmobile_scu_base);
  54        scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
  55
  56        /* Use CPU notifier for reset vector control */
  57        register_cpu_notifier(&shmobile_smp_scu_notifier);
  58}
  59
  60#ifdef CONFIG_HOTPLUG_CPU
  61void shmobile_smp_scu_cpu_die(unsigned int cpu)
  62{
  63        /* For this particular CPU deregister boot vector */
  64        shmobile_smp_hook(cpu, 0, 0);
  65
  66        dsb();
  67        flush_cache_all();
  68
  69        /* disable cache coherency */
  70        scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
  71
  72        /* jump to shared mach-shmobile sleep / reset code */
  73        shmobile_smp_sleep();
  74}
  75
  76static int shmobile_smp_scu_psr_core_disabled(int cpu)
  77{
  78        unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
  79
  80        if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
  81                return 1;
  82
  83        return 0;
  84}
  85
  86int shmobile_smp_scu_cpu_kill(unsigned int cpu)
  87{
  88        int k;
  89
  90        /* this function is running on another CPU than the offline target,
  91         * here we need wait for shutdown code in platform_cpu_die() to
  92         * finish before asking SoC-specific code to power off the CPU core.
  93         */
  94        for (k = 0; k < 1000; k++) {
  95                if (shmobile_smp_scu_psr_core_disabled(cpu))
  96                        return 1;
  97
  98                mdelay(1);
  99        }
 100
 101        return 0;
 102}
 103#endif
 104