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
  30 static void __iomem *cpu_bootaddr;
  31
  32 static DEFINE_SPINLOCK(cpu_lock);
  33
  34 static int
  35 r9a06g032_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
  51 static 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
  90 static 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
  95 CPU_METHOD_OF_DECLARE(r9a06g032_smp,
  96                       "renesas,r9a06g032-smp", &r9a06g032_smp_ops);