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