arch/arm/kernel/devtree.c

   1 /*
   2  *  linux/arch/arm/kernel/devtree.c
   3  *
   4  *  Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.com>
   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/export.h>
  13 #include <linux/errno.h>
  14 #include <linux/types.h>
  15 #include <linux/bootmem.h>
  16 #include <linux/memblock.h>
  17 #include <linux/of.h>
  18 #include <linux/of_fdt.h>
  19 #include <linux/of_irq.h>
  20 #include <linux/of_platform.h>
  21 #include <linux/smp.h>
  22
  23 #include <asm/cputype.h>
  24 #include <asm/setup.h>
  25 #include <asm/page.h>
  26 #include <asm/smp_plat.h>
  27 #include <asm/mach/arch.h>
  28 #include <asm/mach-types.h>
  29
  30
  31 #ifdef CONFIG_SMP
  32 extern struct of_cpu_method __cpu_method_of_table[];
  33
  34 static const struct of_cpu_method __cpu_method_of_table_sentinel
  35         __used __section(__cpu_method_of_table_end);
  36
  37
  38 static int __init set_smp_ops_by_method(struct device_node *node)
  39 {
  40         const char *method;
  41         struct of_cpu_method *m = __cpu_method_of_table;
  42
  43         if (of_property_read_string(node, "enable-method", &method))
  44                 return 0;
  45
  46         for (; m->method; m++)
  47                 if (!strcmp(m->method, method)) {
  48                         smp_set_ops(m->ops);
  49                         return 1;
  50                 }
  51
  52         return 0;
  53 }
  54 #else
  55 static inline int set_smp_ops_by_method(struct device_node *node)
  56 {
  57         return 1;
  58 }
  59 #endif
  60
  61
  62 /*
  63  * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
  64  * and builds the cpu logical map array containing MPIDR values related to
  65  * logical cpus
  66  *
  67  * Updates the cpu possible mask with the number of parsed cpu nodes
  68  */
  69 void __init arm_dt_init_cpu_maps(void)
  70 {
  71         /*
  72          * Temp logical map is initialized with UINT_MAX values that are
  73          * considered invalid logical map entries since the logical map must
  74          * contain a list of MPIDR[23:0] values where MPIDR[31:24] must
  75          * read as 0.
  76          */
  77         struct device_node *cpu, *cpus;
  78         int found_method = 0;
  79         u32 i, j, cpuidx = 1;
  80         u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
  81
  82         u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = MPIDR_INVALID };
  83         bool bootcpu_valid = false;
  84         cpus = of_find_node_by_path("/cpus");
  85
  86         if (!cpus)
  87                 return;
  88
  89         for_each_child_of_node(cpus, cpu) {
  90                 u32 hwid;
  91
  92                 if (of_node_cmp(cpu->type, "cpu"))
  93                         continue;
  94
  95                 pr_debug(" * %s...\n", cpu->full_name);
  96                 /*
  97                  * A device tree containing CPU nodes with missing "reg"
  98                  * properties is considered invalid to build the
  99                  * cpu_logical_map.
 100                  */
 101                 if (of_property_read_u32(cpu, "reg", &hwid)) {
 102                         pr_debug(" * %s missing reg property\n",
 103                                      cpu->full_name);
 104                         return;
 105                 }
 106
 107                 /*
 108                  * 8 MSBs must be set to 0 in the DT since the reg property
 109                  * defines the MPIDR[23:0].
 110                  */
 111                 if (hwid & ~MPIDR_HWID_BITMASK)
 112                         return;
 113
 114                 /*
 115                  * Duplicate MPIDRs are a recipe for disaster.
 116                  * Scan all initialized entries and check for
 117                  * duplicates. If any is found just bail out.
 118                  * temp values were initialized to UINT_MAX
 119                  * to avoid matching valid MPIDR[23:0] values.
 120                  */
 121                 for (j = 0; j < cpuidx; j++)
 122                         if (WARN(tmp_map[j] == hwid, "Duplicate /cpu reg "
 123                                                      "properties in the DT\n"))
 124                                 return;
 125
 126                 /*
 127                  * Build a stashed array of MPIDR values. Numbering scheme
 128                  * requires that if detected the boot CPU must be assigned
 129                  * logical id 0. Other CPUs get sequential indexes starting
 130                  * from 1. If a CPU node with a reg property matching the
 131                  * boot CPU MPIDR is detected, this is recorded so that the
 132                  * logical map built from DT is validated and can be used
 133                  * to override the map created in smp_setup_processor_id().
 134                  */
 135                 if (hwid == mpidr) {
 136                         i = 0;
 137                         bootcpu_valid = true;
 138                 } else {
 139                         i = cpuidx++;
 140                 }
 141
 142                 if (WARN(cpuidx > nr_cpu_ids, "DT /cpu %u nodes greater than "
 143                                                "max cores %u, capping them\n",
 144                                                cpuidx, nr_cpu_ids)) {
 145                         cpuidx = nr_cpu_ids;
 146                         break;
 147                 }
 148
 149                 tmp_map[i] = hwid;
 150
 151                 if (!found_method)
 152                         found_method = set_smp_ops_by_method(cpu);
 153         }
 154
 155         /*
 156          * Fallback to an enable-method in the cpus node if nothing found in
 157          * a cpu node.
 158          */
 159         if (!found_method)
 160                 set_smp_ops_by_method(cpus);
 161
 162         if (!bootcpu_valid) {
 163                 pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
 164                 return;
 165         }
 166
 167         /*
 168          * Since the boot CPU node contains proper data, and all nodes have
 169          * a reg property, the DT CPU list can be considered valid and the
 170          * logical map created in smp_setup_processor_id() can be overridden
 171          */
 172         for (i = 0; i < cpuidx; i++) {
 173                 set_cpu_possible(i, true);
 174                 cpu_logical_map(i) = tmp_map[i];
 175                 pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
 176         }
 177 }
 178
 179 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 180 {
 181         return phys_id == cpu_logical_map(cpu);
 182 }
 183
 184 static const void * __init arch_get_next_mach(const char *const **match)
 185 {
 186         static const struct machine_desc *mdesc = __arch_info_begin;
 187         const struct machine_desc *m = mdesc;
 188
 189         if (m >= __arch_info_end)
 190                 return NULL;
 191
 192         mdesc++;
 193         *match = m->dt_compat;
 194         return m;
 195 }
 196
 197 /**
 198  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
 199  * @dt_phys: physical address of dt blob
 200  *
 201  * If a dtb was passed to the kernel in r2, then use it to choose the
 202  * correct machine_desc and to setup the system.
 203  */
 204 const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 205 {
 206         const struct machine_desc *mdesc, *mdesc_best = NULL;
 207
 208 #ifdef CONFIG_ARCH_MULTIPLATFORM
 209         DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
 210         MACHINE_END
 211
 212         mdesc_best = &__mach_desc_GENERIC_DT;
 213 #endif
 214
 215         if (!dt_phys || !early_init_dt_scan(phys_to_virt(dt_phys)))
 216                 return NULL;
 217
 218         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
 219
 220         if (!mdesc) {
 221                 const char *prop;
 222                 int size;
 223                 unsigned long dt_root;
 224
 225                 early_print("\nError: unrecognized/unsupported "
 226                             "device tree compatible list:\n[ ");
 227
 228                 dt_root = of_get_flat_dt_root();
 229                 prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
 230                 while (size > 0) {
 231                         early_print("'%s' ", prop);
 232                         size -= strlen(prop) + 1;
 233                         prop += strlen(prop) + 1;
 234                 }
 235                 early_print("]\n\n");
 236
 237                 dump_machine_table(); /* does not return */
 238         }
 239
 240         /* Change machine number to match the mdesc we're using */
 241         __machine_arch_type = mdesc->nr;
 242
 243         return mdesc;
 244 }