/*
 * arch/arm64/kernel/topology.c
 *
 * Copyright (C) 2011,2013,2014 Linaro Limited.
 *
 * Based on the arm32 version written by Vincent Guittot in turn based on
 * arch/sh/kernel/topology.c
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/node.h>
#include <linux/nodemask.h>
#include <linux/of.h>
#include <linux/sched.h>

#include <asm/cputype.h>
#include <asm/topology.h>

static int __init get_cpu_for_node(struct device_node *node)
{
        struct device_node *cpu_node;
        int cpu;

        cpu_node = of_parse_phandle(node, "cpu", 0);
        if (!cpu_node)
                return -1;

        for_each_possible_cpu(cpu) {
                if (of_get_cpu_node(cpu, NULL) == cpu_node) {
                        of_node_put(cpu_node);
                        return cpu;
                }
        }

        pr_crit("Unable to find CPU node for %s\n", cpu_node->full_name);

        of_node_put(cpu_node);
        return -1;
}

static int __init parse_core(struct device_node *core, int cluster_id,
                             int core_id)
{
        char name[10];
        bool leaf = true;
        int i = 0;
        int cpu;
        struct device_node *t;

        do {
                snprintf(name, sizeof(name), "thread%d", i);
                t = of_get_child_by_name(core, name);
                if (t) {
                        leaf = false;
                        cpu = get_cpu_for_node(t);
                        if (cpu >= 0) {
                                cpu_topology[cpu].cluster_id = cluster_id;
                                cpu_topology[cpu].core_id = core_id;
                                cpu_topology[cpu].thread_id = i;
                        } else {
                                pr_err("%s: Can't get CPU for thread\n",
                                       t->full_name);
                                of_node_put(t);
                                return -EINVAL;
                        }
                        of_node_put(t);
                }
                i++;
        } while (t);

        cpu = get_cpu_for_node(core);
        if (cpu >= 0) {
                if (!leaf) {
                        pr_err("%s: Core has both threads and CPU\n",
                               core->full_name);
                        return -EINVAL;
                }

                cpu_topology[cpu].cluster_id = cluster_id;
                cpu_topology[cpu].core_id = core_id;
        } else if (leaf) {
                pr_err("%s: Can't get CPU for leaf core\n", core->full_name);
                return -EINVAL;
        }

        return 0;
}

static int __init parse_cluster(struct device_node *cluster, int depth)
{
        char name[10];
        bool leaf = true;
        bool has_cores = false;
        struct device_node *c;
        static int cluster_id __initdata;
        int core_id = 0;
        int i, ret;

        /*
         * First check for child clusters; we currently ignore any
         * information about the nesting of clusters and present the
         * scheduler with a flat list of them.
         */
        i = 0;
        do {
                snprintf(name, sizeof(name), "cluster%d", i);
                c = of_get_child_by_name(cluster, name);
                if (c) {
                        leaf = false;
                        ret = parse_cluster(c, depth + 1);
                        of_node_put(c);
                        if (ret != 0)
                                return ret;
                }
                i++;
        } while (c);

        /* Now check for cores */
        i = 0;
        do {
                snprintf(name, sizeof(name), "core%d", i);
                c = of_get_child_by_name(cluster, name);
                if (c) {
                        has_cores = true;

                        if (depth == 0) {
                                pr_err("%s: cpu-map children should be clusters\n",
                                       c->full_name);
                                of_node_put(c);
                                return -EINVAL;
                        }

                        if (leaf) {
                                ret = parse_core(c, cluster_id, core_id++);
                        } else {
                                pr_err("%s: Non-leaf cluster with core %s\n",
                                       cluster->full_name, name);
                                ret = -EINVAL;
                        }

                        of_node_put(c);
                        if (ret != 0)
                                return ret;
                }
                i++;
        } while (c);

        if (leaf && !has_cores)
                pr_warn("%s: empty cluster\n", cluster->full_name);

        if (leaf)
                cluster_id++;

        return 0;
}

static int __init parse_dt_topology(void)
{
        struct device_node *cn, *map;
        int ret = 0;
        int cpu;

        cn = of_find_node_by_path("/cpus");
        if (!cn) {
                pr_err("No CPU information found in DT\n");
                return 0;
        }

        /*
         * When topology is provided cpu-map is essentially a root
         * cluster with restricted subnodes.
         */
        map = of_get_child_by_name(cn, "cpu-map");
        if (!map)
                goto out;

        ret = parse_cluster(map, 0);
        if (ret != 0)
                goto out_map;

        /*
         * Check that all cores are in the topology; the SMP code will
         * only mark cores described in the DT as possible.
         */
        for_each_possible_cpu(cpu)
                if (cpu_topology[cpu].cluster_id == -1)
                        ret = -EINVAL;

out_map:
        of_node_put(map);
out:
        of_node_put(cn);
        return ret;
}

/*
 * cpu topology table
 */
struct cpu_topology cpu_topology[NR_CPUS];
EXPORT_SYMBOL_GPL(cpu_topology);

const struct cpumask *cpu_coregroup_mask(int cpu)
{
        return &cpu_topology[cpu].core_sibling;
}

static void update_siblings_masks(unsigned int cpuid)
{
        struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
        int cpu;

        /* update core and thread sibling masks */
        for_each_possible_cpu(cpu) {
                cpu_topo = &cpu_topology[cpu];

                if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
                        continue;

                cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
                if (cpu != cpuid)
                        cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);

                if (cpuid_topo->core_id != cpu_topo->core_id)
                        continue;

                cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
                if (cpu != cpuid)
                        cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
        }
}

void store_cpu_topology(unsigned int cpuid)
{
        struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
        u64 mpidr;

        if (cpuid_topo->cluster_id != -1)
                goto topology_populated;

        mpidr = read_cpuid_mpidr();

        /* Uniprocessor systems can rely on default topology values */
        if (mpidr & MPIDR_UP_BITMASK)
                return;

        /* Create cpu topology mapping based on MPIDR. */
        if (mpidr & MPIDR_MT_BITMASK) {
                /* Multiprocessor system : Multi-threads per core */
                cpuid_topo->thread_id  = MPIDR_AFFINITY_LEVEL(mpidr, 0);
                cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 1);
                cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 2) |
                                         MPIDR_AFFINITY_LEVEL(mpidr, 3) << 8;
        } else {
                /* Multiprocessor system : Single-thread per core */
                cpuid_topo->thread_id  = -1;
                cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 0);
                cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 1) |
                                         MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
                                         MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
        }

        pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
                 cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id,
                 cpuid_topo->thread_id, mpidr);

topology_populated:
        update_siblings_masks(cpuid);
}

static void __init reset_cpu_topology(void)
{
        unsigned int cpu;

        for_each_possible_cpu(cpu) {
                struct cpu_topology *cpu_topo = &cpu_topology[cpu];

                cpu_topo->thread_id = -1;
                cpu_topo->core_id = 0;
                cpu_topo->cluster_id = -1;

                cpumask_clear(&cpu_topo->core_sibling);
                cpumask_set_cpu(cpu, &cpu_topo->core_sibling);
                cpumask_clear(&cpu_topo->thread_sibling);
                cpumask_set_cpu(cpu, &cpu_topo->thread_sibling);
        }
}

void __init init_cpu_topology(void)
{
        reset_cpu_topology();

        /*
         * Discard anything that was parsed if we hit an error so we
         * don't use partial information.
         */
        if (of_have_populated_dt() && parse_dt_topology())
                reset_cpu_topology();
}