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                 const __be32 *cell;
  92                 int prop_bytes;
  93                 u32 hwid;
  94
  95                 if (of_node_cmp(cpu->type, "cpu"))
  96                         continue;
  97
  98                 pr_debug(" * %s...\n", cpu->full_name);
  99                 /*
 100                  * A device tree containing CPU nodes with missing "reg"
 101                  * properties is considered invalid to build the
 102                  * cpu_logical_map.
 103                  */
 104                 cell = of_get_property(cpu, "reg", &prop_bytes);
 105                 if (!cell || prop_bytes < sizeof(*cell)) {
 106                         pr_debug(" * %s missing reg property\n",
 107                                      cpu->full_name);
 108                         of_node_put(cpu);
 109                         return;
 110                 }
 111
 112                 /*
 113                  * Bits n:24 must be set to 0 in the DT since the reg property
 114                  * defines the MPIDR[23:0].
 115                  */
 116                 do {
 117                         hwid = be32_to_cpu(*cell++);
 118                         prop_bytes -= sizeof(*cell);
 119                 } while (!hwid && prop_bytes > 0);
 120
 121                 if (prop_bytes || (hwid & ~MPIDR_HWID_BITMASK)) {
 122                         of_node_put(cpu);
 123                         return;
 124                 }
 125
 126                 /*
 127                  * Duplicate MPIDRs are a recipe for disaster.
 128                  * Scan all initialized entries and check for
 129                  * duplicates. If any is found just bail out.
 130                  * temp values were initialized to UINT_MAX
 131                  * to avoid matching valid MPIDR[23:0] values.
 132                  */
 133                 for (j = 0; j < cpuidx; j++)
 134                         if (WARN(tmp_map[j] == hwid,
 135                                  "Duplicate /cpu reg properties in the DT\n")) {
 136                                 of_node_put(cpu);
 137                                 return;
 138                         }
 139
 140                 /*
 141                  * Build a stashed array of MPIDR values. Numbering scheme
 142                  * requires that if detected the boot CPU must be assigned
 143                  * logical id 0. Other CPUs get sequential indexes starting
 144                  * from 1. If a CPU node with a reg property matching the
 145                  * boot CPU MPIDR is detected, this is recorded so that the
 146                  * logical map built from DT is validated and can be used
 147                  * to override the map created in smp_setup_processor_id().
 148                  */
 149                 if (hwid == mpidr) {
 150                         i = 0;
 151                         bootcpu_valid = true;
 152                 } else {
 153                         i = cpuidx++;
 154                 }
 155
 156                 if (WARN(cpuidx > nr_cpu_ids, "DT /cpu %u nodes greater than "
 157                                                "max cores %u, capping them\n",
 158                                                cpuidx, nr_cpu_ids)) {
 159                         cpuidx = nr_cpu_ids;
 160                         of_node_put(cpu);
 161                         break;
 162                 }
 163
 164                 tmp_map[i] = hwid;
 165
 166                 if (!found_method)
 167                         found_method = set_smp_ops_by_method(cpu);
 168         }
 169
 170         /*
 171          * Fallback to an enable-method in the cpus node if nothing found in
 172          * a cpu node.
 173          */
 174         if (!found_method)
 175                 set_smp_ops_by_method(cpus);
 176
 177         if (!bootcpu_valid) {
 178                 pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
 179                 return;
 180         }
 181
 182         /*
 183          * Since the boot CPU node contains proper data, and all nodes have
 184          * a reg property, the DT CPU list can be considered valid and the
 185          * logical map created in smp_setup_processor_id() can be overridden
 186          */
 187         for (i = 0; i < cpuidx; i++) {
 188                 set_cpu_possible(i, true);
 189                 cpu_logical_map(i) = tmp_map[i];
 190                 pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
 191         }
 192 }
 193
 194 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 195 {
 196         return phys_id == cpu_logical_map(cpu);
 197 }
 198
 199 static const void * __init arch_get_next_mach(const char *const **match)
 200 {
 201         static const struct machine_desc *mdesc = __arch_info_begin;
 202         const struct machine_desc *m = mdesc;
 203
 204         if (m >= __arch_info_end)
 205                 return NULL;
 206
 207         mdesc++;
 208         *match = m->dt_compat;
 209         return m;
 210 }
 211
 212 /**
 213  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
 214  * @dt_phys: physical address of dt blob
 215  *
 216  * If a dtb was passed to the kernel in r2, then use it to choose the
 217  * correct machine_desc and to setup the system.
 218  */
 219 const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 220 {
 221         const struct machine_desc *mdesc, *mdesc_best = NULL;
 222
 223 #if defined(CONFIG_ARCH_MULTIPLATFORM) || defined(CONFIG_ARM_SINGLE_ARMV7M)
 224         DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
 225                 .l2c_aux_val = 0x0,
 226                 .l2c_aux_mask = ~0x0,
 227         MACHINE_END
 228
 229         mdesc_best = &__mach_desc_GENERIC_DT;
 230 #endif
 231
 232         if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
 233                 return NULL;
 234
 235         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
 236
 237         if (!mdesc) {
 238                 const char *prop;
 239                 int size;
 240                 unsigned long dt_root;
 241
 242                 early_print("\nError: unrecognized/unsupported "
 243                             "device tree compatible list:\n[ ");
 244
 245                 dt_root = of_get_flat_dt_root();
 246                 prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
 247                 while (size > 0) {
 248                         early_print("'%s' ", prop);
 249                         size -= strlen(prop) + 1;
 250                         prop += strlen(prop) + 1;
 251                 }
 252                 early_print("]\n\n");
 253
 254                 dump_machine_table(); /* does not return */
 255         }
 256
 257         /* We really don't want to do this, but sometimes firmware provides buggy data */
 258         if (mdesc->dt_fixup)
 259                 mdesc->dt_fixup();
 260
 261         early_init_dt_scan_nodes();
 262
 263         /* Change machine number to match the mdesc we're using */
 264         __machine_arch_type = mdesc->nr;
 265
 266         return mdesc;
 267 }