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                         of_node_put(cpu);
 105                         return;
 106                 }
 107
 108                 /*
 109                  * 8 MSBs must be set to 0 in the DT since the reg property
 110                  * defines the MPIDR[23:0].
 111                  */
 112                 if (hwid & ~MPIDR_HWID_BITMASK) {
 113                         of_node_put(cpu);
 114                         return;
 115                 }
 116
 117                 /*
 118                  * Duplicate MPIDRs are a recipe for disaster.
 119                  * Scan all initialized entries and check for
 120                  * duplicates. If any is found just bail out.
 121                  * temp values were initialized to UINT_MAX
 122                  * to avoid matching valid MPIDR[23:0] values.
 123                  */
 124                 for (j = 0; j < cpuidx; j++)
 125                         if (WARN(tmp_map[j] == hwid,
 126                                  "Duplicate /cpu reg properties in the DT\n")) {
 127                                 of_node_put(cpu);
 128                                 return;
 129                         }
 130
 131                 /*
 132                  * Build a stashed array of MPIDR values. Numbering scheme
 133                  * requires that if detected the boot CPU must be assigned
 134                  * logical id 0. Other CPUs get sequential indexes starting
 135                  * from 1. If a CPU node with a reg property matching the
 136                  * boot CPU MPIDR is detected, this is recorded so that the
 137                  * logical map built from DT is validated and can be used
 138                  * to override the map created in smp_setup_processor_id().
 139                  */
 140                 if (hwid == mpidr) {
 141                         i = 0;
 142                         bootcpu_valid = true;
 143                 } else {
 144                         i = cpuidx++;
 145                 }
 146
 147                 if (WARN(cpuidx > nr_cpu_ids, "DT /cpu %u nodes greater than "
 148                                                "max cores %u, capping them\n",
 149                                                cpuidx, nr_cpu_ids)) {
 150                         cpuidx = nr_cpu_ids;
 151                         of_node_put(cpu);
 152                         break;
 153                 }
 154
 155                 tmp_map[i] = hwid;
 156
 157                 if (!found_method)
 158                         found_method = set_smp_ops_by_method(cpu);
 159         }
 160
 161         /*
 162          * Fallback to an enable-method in the cpus node if nothing found in
 163          * a cpu node.
 164          */
 165         if (!found_method)
 166                 set_smp_ops_by_method(cpus);
 167
 168         if (!bootcpu_valid) {
 169                 pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
 170                 return;
 171         }
 172
 173         /*
 174          * Since the boot CPU node contains proper data, and all nodes have
 175          * a reg property, the DT CPU list can be considered valid and the
 176          * logical map created in smp_setup_processor_id() can be overridden
 177          */
 178         for (i = 0; i < cpuidx; i++) {
 179                 set_cpu_possible(i, true);
 180                 cpu_logical_map(i) = tmp_map[i];
 181                 pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
 182         }
 183 }
 184
 185 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 186 {
 187         return phys_id == cpu_logical_map(cpu);
 188 }
 189
 190 static const void * __init arch_get_next_mach(const char *const **match)
 191 {
 192         static const struct machine_desc *mdesc = __arch_info_begin;
 193         const struct machine_desc *m = mdesc;
 194
 195         if (m >= __arch_info_end)
 196                 return NULL;
 197
 198         mdesc++;
 199         *match = m->dt_compat;
 200         return m;
 201 }
 202
 203 /**
 204  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
 205  * @dt_phys: physical address of dt blob
 206  *
 207  * If a dtb was passed to the kernel in r2, then use it to choose the
 208  * correct machine_desc and to setup the system.
 209  */
 210 const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 211 {
 212         const struct machine_desc *mdesc, *mdesc_best = NULL;
 213
 214 #ifdef CONFIG_ARCH_MULTIPLATFORM
 215         DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
 216         MACHINE_END
 217
 218         mdesc_best = &__mach_desc_GENERIC_DT;
 219 #endif
 220
 221         if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
 222                 return NULL;
 223
 224         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
 225
 226         if (!mdesc) {
 227                 const char *prop;
 228                 int size;
 229                 unsigned long dt_root;
 230
 231                 early_print("\nError: unrecognized/unsupported "
 232                             "device tree compatible list:\n[ ");
 233
 234                 dt_root = of_get_flat_dt_root();
 235                 prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
 236                 while (size > 0) {
 237                         early_print("'%s' ", prop);
 238                         size -= strlen(prop) + 1;
 239                         prop += strlen(prop) + 1;
 240                 }
 241                 early_print("]\n\n");
 242
 243                 dump_machine_table(); /* does not return */
 244         }
 245
 246         /* We really don't want to do this, but sometimes firmware provides buggy data */
 247         if (mdesc->dt_fixup)
 248                 mdesc->dt_fixup();
 249
 250         early_init_dt_scan_nodes();
 251
 252         /* Change machine number to match the mdesc we're using */
 253         __machine_arch_type = mdesc->nr;
 254
 255         return mdesc;
 256 }