LXR linux/drivers/soc/renesas/r9a06g032-smp.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * R9A06G032 Second CA7 enabler.
   4 *
   5 * Copyright (C) 2018 Renesas Electronics Europe Limited
   6 *
   7 * Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>
   8 * Derived from actions,s500-smp
   9 */
  10
  11#include <linux/io.h>
  12#include <linux/of.h>
  13#include <linux/of_address.h>
  14#include <linux/smp.h>
  15
  16/*
  17 * The second CPU is parked in ROM at boot time. It requires waking it after
  18 * writing an address into the BOOTADDR register of sysctrl.
  19 *
  20 * So the default value of the "cpu-release-addr" corresponds to BOOTADDR...
  21 *
  22 * *However* the BOOTADDR register is not available when the kernel
  23 * starts in NONSEC mode.
  24 *
  25 * So for NONSEC mode, the bootloader re-parks the second CPU into a pen
  26 * in SRAM, and changes the "cpu-release-addr" of linux's DT to a SRAM address,
  27 * which is not restricted.
  28 */
  29
  30static void __iomem *cpu_bootaddr;
  31
  32static DEFINE_SPINLOCK(cpu_lock);
  33
  34static int
  35r9a06g032_smp_boot_secondary(unsigned int cpu,
  36                             struct task_struct *idle)
  37{
  38        if (!cpu_bootaddr)
  39                return -ENODEV;
  40
  41        spin_lock(&cpu_lock);
  42
  43        writel(__pa_symbol(secondary_startup), cpu_bootaddr);
  44        arch_send_wakeup_ipi_mask(cpumask_of(cpu));
  45
  46        spin_unlock(&cpu_lock);
  47
  48        return 0;
  49}
  50
  51static void __init r9a06g032_smp_prepare_cpus(unsigned int max_cpus)
  52{
  53        struct device_node *dn;
  54        int ret = -EINVAL, dns;
  55        u32 bootaddr;
  56
  57        dn = of_get_cpu_node(1, NULL);
  58        if (!dn) {
  59                pr_err("CPU#1: missing device tree node\n");
  60                return;
  61        }
  62        /*
  63         * Determine the address from which the CPU is polling.
  64         * The bootloader *does* change this property.
  65         * Note: The property can be either 64 or 32 bits, so handle both cases
  66         */
  67        if (of_find_property(dn, "cpu-release-addr", &dns)) {
  68                if (dns == sizeof(u64)) {
  69                        u64 temp;
  70
  71                        ret = of_property_read_u64(dn,
  72                                                   "cpu-release-addr", &temp);
  73                        bootaddr = temp;
  74                } else {
  75                        ret = of_property_read_u32(dn,
  76                                                   "cpu-release-addr",
  77                                                   &bootaddr);
  78                }
  79        }
  80        of_node_put(dn);
  81        if (ret) {
  82                pr_err("CPU#1: invalid cpu-release-addr property\n");
  83                return;
  84        }
  85        pr_info("CPU#1: cpu-release-addr %08x\n", bootaddr);
  86
  87        cpu_bootaddr = ioremap(bootaddr, sizeof(bootaddr));
  88}
  89
  90static const struct smp_operations r9a06g032_smp_ops __initconst = {
  91        .smp_prepare_cpus = r9a06g032_smp_prepare_cpus,
  92        .smp_boot_secondary = r9a06g032_smp_boot_secondary,
  93};
  94
  95CPU_METHOD_OF_DECLARE(r9a06g032_smp,
  96                      "renesas,r9a06g032-smp", &r9a06g032_smp_ops);
  97