root/arch/arm/kernel/devtree.c

DEFINITIONS

1. set_smp_ops_by_method
2. set_smp_ops_by_method
3. arm_dt_init_cpu_maps
4. arch_match_cpu_phys_id
5. arch_get_next_mach
6. setup_machine_fdt

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/kernel/devtree.c
   4  *
   5  *  Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.com>
   6  */
   7 
   8 #include <linux/init.h>
   9 #include <linux/export.h>
  10 #include <linux/errno.h>
  11 #include <linux/types.h>
  12 #include <linux/memblock.h>
  13 #include <linux/of.h>
  14 #include <linux/of_fdt.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/of_platform.h>
  17 #include <linux/smp.h>
  18 
  19 #include <asm/cputype.h>
  20 #include <asm/setup.h>
  21 #include <asm/page.h>
  22 #include <asm/prom.h>
  23 #include <asm/smp_plat.h>
  24 #include <asm/mach/arch.h>
  25 #include <asm/mach-types.h>
  26 
  27 
  28 #ifdef CONFIG_SMP
  29 extern struct of_cpu_method __cpu_method_of_table[];
  30 
  31 static const struct of_cpu_method __cpu_method_of_table_sentinel
  32         __used __section(__cpu_method_of_table_end);
  33 
  34 
  35 static int __init set_smp_ops_by_method(struct device_node *node)
  36 {
  37         const char *method;
  38         struct of_cpu_method *m = __cpu_method_of_table;
  39 
  40         if (of_property_read_string(node, "enable-method", &method))
  41                 return 0;
  42 
  43         for (; m->method; m++)
  44                 if (!strcmp(m->method, method)) {
  45                         smp_set_ops(m->ops);
  46                         return 1;
  47                 }
  48 
  49         return 0;
  50 }
  51 #else
  52 static inline int set_smp_ops_by_method(struct device_node *node)
  53 {
  54         return 1;
  55 }
  56 #endif
  57 
  58 
  59 /*
  60  * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
  61  * and builds the cpu logical map array containing MPIDR values related to
  62  * logical cpus
  63  *
  64  * Updates the cpu possible mask with the number of parsed cpu nodes
  65  */
  66 void __init arm_dt_init_cpu_maps(void)
  67 {
  68         /*
  69          * Temp logical map is initialized with UINT_MAX values that are
  70          * considered invalid logical map entries since the logical map must
  71          * contain a list of MPIDR[23:0] values where MPIDR[31:24] must
  72          * read as 0.
  73          */
  74         struct device_node *cpu, *cpus;
  75         int found_method = 0;
  76         u32 i, j, cpuidx = 1;
  77         u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
  78 
  79         u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = MPIDR_INVALID };
  80         bool bootcpu_valid = false;
  81         cpus = of_find_node_by_path("/cpus");
  82 
  83         if (!cpus)
  84                 return;
  85 
  86         for_each_of_cpu_node(cpu) {
  87                 const __be32 *cell;
  88                 int prop_bytes;
  89                 u32 hwid;
  90 
  91                 pr_debug(" * %pOF...\n", cpu);
  92                 /*
  93                  * A device tree containing CPU nodes with missing "reg"
  94                  * properties is considered invalid to build the
  95                  * cpu_logical_map.
  96                  */
  97                 cell = of_get_property(cpu, "reg", &prop_bytes);
  98                 if (!cell || prop_bytes < sizeof(*cell)) {
  99                         pr_debug(" * %pOF missing reg property\n", cpu);
 100                         of_node_put(cpu);
 101                         return;
 102                 }
 103 
 104                 /*
 105                  * Bits n:24 must be set to 0 in the DT since the reg property
 106                  * defines the MPIDR[23:0].
 107                  */
 108                 do {
 109                         hwid = be32_to_cpu(*cell++);
 110                         prop_bytes -= sizeof(*cell);
 111                 } while (!hwid && prop_bytes > 0);
 112 
 113                 if (prop_bytes || (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 }