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/prom.h>
  27 #include <asm/smp_plat.h>
  28 #include <asm/mach/arch.h>
  29 #include <asm/mach-types.h>
  30
  31
  32 #ifdef CONFIG_SMP
  33 extern struct of_cpu_method __cpu_method_of_table[];
  34
  35 static const struct of_cpu_method __cpu_method_of_table_sentinel
  36         __used __section(__cpu_method_of_table_end);
  37
  38
  39 static int __init set_smp_ops_by_method(struct device_node *node)
  40 {
  41         const char *method;
  42         struct of_cpu_method *m = __cpu_method_of_table;
  43
  44         if (of_property_read_string(node, "enable-method", &method))
  45                 return 0;
  46
  47         for (; m->method; m++)
  48                 if (!strcmp(m->method, method)) {
  49                         smp_set_ops(m->ops);
  50                         return 1;
  51                 }
  52
  53         return 0;
  54 }
  55 #else
  56 static inline int set_smp_ops_by_method(struct device_node *node)
  57 {
  58         return 1;
  59 }
  60 #endif
  61
  62
  63 /*
  64  * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
  65  * and builds the cpu logical map array containing MPIDR values related to
  66  * logical cpus
  67  *
  68  * Updates the cpu possible mask with the number of parsed cpu nodes
  69  */
  70 void __init arm_dt_init_cpu_maps(void)
  71 {
  72         /*
  73          * Temp logical map is initialized with UINT_MAX values that are
  74          * considered invalid logical map entries since the logical map must
  75          * contain a list of MPIDR[23:0] values where MPIDR[31:24] must
  76          * read as 0.
  77          */
  78         struct device_node *cpu, *cpus;
  79         int found_method = 0;
  80         u32 i, j, cpuidx = 1;
  81         u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
  82
  83         u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = MPIDR_INVALID };
  84         bool bootcpu_valid = false;
  85         cpus = of_find_node_by_path("/cpus");
  86
  87         if (!cpus)
  88                 return;
  89
  90         for_each_child_of_node(cpus, cpu) {
  91                 u32 hwid;
  92
  93                 if (of_node_cmp(cpu->type, "cpu"))
  94                         continue;
  95
  96                 pr_debug(" * %s...\n", cpu->full_name);
  97                 /*
  98                  * A device tree containing CPU nodes with missing "reg"
  99                  * properties is considered invalid to build the
 100                  * cpu_logical_map.
 101                  */
 102                 if (of_property_read_u32(cpu, "reg", &hwid)) {
 103                         pr_debug(" * %s missing reg property\n",
 104                                      cpu->full_name);
 105                         of_node_put(cpu);
 106                         return;
 107                 }
 108
 109                 /*
 110                  * 8 MSBs must be set to 0 in the DT since the reg property
 111                  * defines the MPIDR[23:0].
 112                  */
 113                 if (hwid & ~MPIDR_HWID_BITMASK) {
 114                         of_node_put(cpu);
 115                         return;
 116                 }
 117
 118                 /*
 119                  * Duplicate MPIDRs are a recipe for disaster.
 120                  * Scan all initialized entries and check for
 121                  * duplicates. If any is found just bail out.
 122                  * temp values were initialized to UINT_MAX
 123                  * to avoid matching valid MPIDR[23:0] values.
 124                  */
 125                 for (j = 0; j < cpuidx; j++)
 126                         if (WARN(tmp_map[j] == hwid,
 127                                  "Duplicate /cpu reg properties in the DT\n")) {
 128                                 of_node_put(cpu);
 129                                 return;
 130                         }
 131
 132                 /*
 133                  * Build a stashed array of MPIDR values. Numbering scheme
 134                  * requires that if detected the boot CPU must be assigned
 135                  * logical id 0. Other CPUs get sequential indexes starting
 136                  * from 1. If a CPU node with a reg property matching the
 137                  * boot CPU MPIDR is detected, this is recorded so that the
 138                  * logical map built from DT is validated and can be used
 139                  * to override the map created in smp_setup_processor_id().
 140                  */
 141                 if (hwid == mpidr) {
 142                         i = 0;
 143                         bootcpu_valid = true;
 144                 } else {
 145                         i = cpuidx++;
 146                 }
 147
 148                 if (WARN(cpuidx > nr_cpu_ids, "DT /cpu %u nodes greater than "
 149                                                "max cores %u, capping them\n",
 150                                                cpuidx, nr_cpu_ids)) {
 151                         cpuidx = nr_cpu_ids;
 152                         of_node_put(cpu);
 153                         break;
 154                 }
 155
 156                 tmp_map[i] = hwid;
 157
 158                 if (!found_method)
 159                         found_method = set_smp_ops_by_method(cpu);
 160         }
 161
 162         /*
 163          * Fallback to an enable-method in the cpus node if nothing found in
 164          * a cpu node.
 165          */
 166         if (!found_method)
 167                 set_smp_ops_by_method(cpus);
 168
 169         if (!bootcpu_valid) {
 170                 pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
 171                 return;
 172         }
 173
 174         /*
 175          * Since the boot CPU node contains proper data, and all nodes have
 176          * a reg property, the DT CPU list can be considered valid and the
 177          * logical map created in smp_setup_processor_id() can be overridden
 178          */
 179         for (i = 0; i < cpuidx; i++) {
 180                 set_cpu_possible(i, true);
 181                 cpu_logical_map(i) = tmp_map[i];
 182                 pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
 183         }
 184 }
 185
 186 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 187 {
 188         return phys_id == cpu_logical_map(cpu);
 189 }
 190
 191 static const void * __init arch_get_next_mach(const char *const **match)
 192 {
 193         static const struct machine_desc *mdesc = __arch_info_begin;
 194         const struct machine_desc *m = mdesc;
 195
 196         if (m >= __arch_info_end)
 197                 return NULL;
 198
 199         mdesc++;
 200         *match = m->dt_compat;
 201         return m;
 202 }
 203
 204 /**
 205  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
 206  * @dt_phys: physical address of dt blob
 207  *
 208  * If a dtb was passed to the kernel in r2, then use it to choose the
 209  * correct machine_desc and to setup the system.
 210  */
 211 const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 212 {
 213         const struct machine_desc *mdesc, *mdesc_best = NULL;
 214
 215 #if defined(CONFIG_ARCH_MULTIPLATFORM) || defined(CONFIG_ARM_SINGLE_ARMV7M)
 216         DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
 217                 .l2c_aux_val = 0x0,
 218                 .l2c_aux_mask = ~0x0,
 219         MACHINE_END
 220
 221         mdesc_best = &__mach_desc_GENERIC_DT;
 222 #endif
 223
 224         if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
 225                 return NULL;
 226
 227         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
 228
 229         if (!mdesc) {
 230                 const char *prop;
 231                 int size;
 232                 unsigned long dt_root;
 233
 234                 early_print("\nError: unrecognized/unsupported "
 235                             "device tree compatible list:\n[ ");
 236
 237                 dt_root = of_get_flat_dt_root();
 238                 prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
 239                 while (size > 0) {
 240                         early_print("'%s' ", prop);
 241                         size -= strlen(prop) + 1;
 242                         prop += strlen(prop) + 1;
 243                 }
 244                 early_print("]\n\n");
 245
 246                 dump_machine_table(); /* does not return */
 247         }
 248
 249         /* We really don't want to do this, but sometimes firmware provides buggy data */
 250         if (mdesc->dt_fixup)
 251                 mdesc->dt_fixup();
 252
 253         early_init_dt_scan_nodes();
 254
 255         /* Change machine number to match the mdesc we're using */
 256         __machine_arch_type = mdesc->nr;
 257
 258         return mdesc;
 259 }