arch/arm/mach-axxia/platsmp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/arch/arm/mach-axxia/platsmp.c
   4  *
   5  * Copyright (C) 2012 LSI Corporation
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/io.h>
  10 #include <linux/smp.h>
  11 #include <linux/of.h>
  12 #include <linux/of_address.h>
  13 #include <asm/cacheflush.h>
  14
  15 /* Syscon register offsets for releasing cores from reset */
  16 #define SC_CRIT_WRITE_KEY       0x1000
  17 #define SC_RST_CPU_HOLD         0x1010
  18
  19 /*
  20  * Write the kernel entry point for secondary CPUs to the specified address
  21  */
  22 static void write_release_addr(u32 release_phys)
  23 {
  24         u32 *virt = (u32 *) phys_to_virt(release_phys);
  25         writel_relaxed(__pa_symbol(secondary_startup), virt);
  26         /* Make sure this store is visible to other CPUs */
  27         smp_wmb();
  28         __cpuc_flush_dcache_area(virt, sizeof(u32));
  29 }
  30
  31 static int axxia_boot_secondary(unsigned int cpu, struct task_struct *idle)
  32 {
  33         struct device_node *syscon_np;
  34         void __iomem *syscon;
  35         u32 tmp;
  36
  37         syscon_np = of_find_compatible_node(NULL, NULL, "lsi,axxia-syscon");
  38         if (!syscon_np)
  39                 return -ENOENT;
  40
  41         syscon = of_iomap(syscon_np, 0);
  42         of_node_put(syscon_np);
  43         if (!syscon)
  44                 return -ENOMEM;
  45
  46         tmp = readl(syscon + SC_RST_CPU_HOLD);
  47         writel(0xab, syscon + SC_CRIT_WRITE_KEY);
  48         tmp &= ~(1 << cpu);
  49         writel(tmp, syscon + SC_RST_CPU_HOLD);
  50
  51         return 0;
  52 }
  53
  54 static void __init axxia_smp_prepare_cpus(unsigned int max_cpus)
  55 {
  56         int cpu_count = 0;
  57         int cpu;
  58
  59         /*
  60          * Initialise the present map, which describes the set of CPUs actually
  61          * populated at the present time.
  62          */
  63         for_each_possible_cpu(cpu) {
  64                 struct device_node *np;
  65                 u32 release_phys;
  66
  67                 np = of_get_cpu_node(cpu, NULL);
  68                 if (!np)
  69                         continue;
  70                 if (of_property_read_u32(np, "cpu-release-addr", &release_phys))
  71                         continue;
  72
  73                 if (cpu_count < max_cpus) {
  74                         set_cpu_present(cpu, true);
  75                         cpu_count++;
  76                 }
  77
  78                 if (release_phys != 0)
  79                         write_release_addr(release_phys);
  80         }
  81 }
  82
  83 static const struct smp_operations axxia_smp_ops __initconst = {
  84         .smp_prepare_cpus       = axxia_smp_prepare_cpus,
  85         .smp_boot_secondary     = axxia_boot_secondary,
  86 };
  87 CPU_METHOD_OF_DECLARE(axxia_smp, "lsi,syscon-release", &axxia_smp_ops);