arch/arm/mach-axxia/platsmp.c

   1 /*
   2  * linux/arch/arm/mach-axxia/platsmp.c
   3  *
   4  * Copyright (C) 2012 LSI Corporation
   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
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/smp.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <asm/cacheflush.h>
  17
  18 /* Syscon register offsets for releasing cores from reset */
  19 #define SC_CRIT_WRITE_KEY       0x1000
  20 #define SC_RST_CPU_HOLD         0x1010
  21
  22 /*
  23  * Write the kernel entry point for secondary CPUs to the specified address
  24  */
  25 static void write_release_addr(u32 release_phys)
  26 {
  27         u32 *virt = (u32 *) phys_to_virt(release_phys);
  28         writel_relaxed(virt_to_phys(secondary_startup), virt);
  29         /* Make sure this store is visible to other CPUs */
  30         smp_wmb();
  31         __cpuc_flush_dcache_area(virt, sizeof(u32));
  32 }
  33
  34 static int axxia_boot_secondary(unsigned int cpu, struct task_struct *idle)
  35 {
  36         struct device_node *syscon_np;
  37         void __iomem *syscon;
  38         u32 tmp;
  39
  40         syscon_np = of_find_compatible_node(NULL, NULL, "lsi,axxia-syscon");
  41         if (!syscon_np)
  42                 return -ENOENT;
  43
  44         syscon = of_iomap(syscon_np, 0);
  45         if (!syscon)
  46                 return -ENOMEM;
  47
  48         tmp = readl(syscon + SC_RST_CPU_HOLD);
  49         writel(0xab, syscon + SC_CRIT_WRITE_KEY);
  50         tmp &= ~(1 << cpu);
  51         writel(tmp, syscon + SC_RST_CPU_HOLD);
  52
  53         return 0;
  54 }
  55
  56 static void __init axxia_smp_prepare_cpus(unsigned int max_cpus)
  57 {
  58         int cpu_count = 0;
  59         int cpu;
  60
  61         /*
  62          * Initialise the present map, which describes the set of CPUs actually
  63          * populated at the present time.
  64          */
  65         for_each_possible_cpu(cpu) {
  66                 struct device_node *np;
  67                 u32 release_phys;
  68
  69                 np = of_get_cpu_node(cpu, NULL);
  70                 if (!np)
  71                         continue;
  72                 if (of_property_read_u32(np, "cpu-release-addr", &release_phys))
  73                         continue;
  74
  75                 if (cpu_count < max_cpus) {
  76                         set_cpu_present(cpu, true);
  77                         cpu_count++;
  78                 }
  79
  80                 if (release_phys != 0)
  81                         write_release_addr(release_phys);
  82         }
  83 }
  84
  85 static const struct smp_operations axxia_smp_ops __initconst = {
  86         .smp_prepare_cpus       = axxia_smp_prepare_cpus,
  87         .smp_boot_secondary     = axxia_boot_secondary,
  88 };
  89 CPU_METHOD_OF_DECLARE(axxia_smp, "lsi,syscon-release", &axxia_smp_ops);