linux/arch/arm/kernel/devtree.c
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   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
  29extern struct of_cpu_method __cpu_method_of_table[];
  30
  31static const struct of_cpu_method __cpu_method_of_table_sentinel
  32        __used __section(__cpu_method_of_table_end);
  33
  34
  35static 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
  52static 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 */
  66void __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
 186bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 187{
 188        return phys_id == cpu_logical_map(cpu);
 189}
 190
 191static 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 */
 211const 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}
 260