sched/headers: Prepare for new header dependencies before moving code to <linux/sched...

[mirror_ubuntu-bionic-kernel.git] / arch / arm / kernel / topology.c

/*
 * arch/arm/kernel/topology.c
 *
 * Copyright (C) 2011 Linaro Limited.
 * Written by: Vincent Guittot
 *
 * 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/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/export.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 <linux/sched/topology.h>
#include <linux/slab.h>
#include <linux/string.h>

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

/*
 * cpu capacity scale management
 */

/*
 * cpu capacity table
 * This per cpu data structure describes the relative capacity of each core.
 * On a heteregenous system, cores don't have the same computation capacity
 * and we reflect that difference in the cpu_capacity field so the scheduler
 * can take this difference into account during load balance. A per cpu
 * structure is preferred because each CPU updates its own cpu_capacity field
 * during the load balance except for idle cores. One idle core is selected
 * to run the rebalance_domains for all idle cores and the cpu_capacity can be
 * updated during this sequence.
 */
static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
static DEFINE_MUTEX(cpu_scale_mutex);

unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
{
        return per_cpu(cpu_scale, cpu);
}

static void set_capacity_scale(unsigned int cpu, unsigned long capacity)
{
        per_cpu(cpu_scale, cpu) = capacity;
}

#ifdef CONFIG_PROC_SYSCTL
static ssize_t cpu_capacity_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct cpu *cpu = container_of(dev, struct cpu, dev);

        return sprintf(buf, "%lu\n",
                        arch_scale_cpu_capacity(NULL, cpu->dev.id));
}

static ssize_t cpu_capacity_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf,
                                  size_t count)
{
        struct cpu *cpu = container_of(dev, struct cpu, dev);
        int this_cpu = cpu->dev.id, i;
        unsigned long new_capacity;
        ssize_t ret;

        if (count) {
                ret = kstrtoul(buf, 0, &new_capacity);
                if (ret)
                        return ret;
                if (new_capacity > SCHED_CAPACITY_SCALE)
                        return -EINVAL;

                mutex_lock(&cpu_scale_mutex);
                for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
                        set_capacity_scale(i, new_capacity);
                mutex_unlock(&cpu_scale_mutex);
        }

        return count;
}

static DEVICE_ATTR_RW(cpu_capacity);

static int register_cpu_capacity_sysctl(void)
{
        int i;
        struct device *cpu;

        for_each_possible_cpu(i) {
                cpu = get_cpu_device(i);
                if (!cpu) {
                        pr_err("%s: too early to get CPU%d device!\n",
                               __func__, i);
                        continue;
                }
                device_create_file(cpu, &dev_attr_cpu_capacity);
        }

        return 0;
}
subsys_initcall(register_cpu_capacity_sysctl);
#endif

#ifdef CONFIG_OF
struct cpu_efficiency {
        const char *compatible;
        unsigned long efficiency;
};

/*
 * Table of relative efficiency of each processors
 * The efficiency value must fit in 20bit and the final
 * cpu_scale value must be in the range
 *   0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2
 * in order to return at most 1 when DIV_ROUND_CLOSEST
 * is used to compute the capacity of a CPU.
 * Processors that are not defined in the table,
 * use the default SCHED_CAPACITY_SCALE value for cpu_scale.
 */
static const struct cpu_efficiency table_efficiency[] = {
        {"arm,cortex-a15", 3891},
        {"arm,cortex-a7",  2048},
        {NULL, },
};

static unsigned long *__cpu_capacity;
#define cpu_capacity(cpu)       __cpu_capacity[cpu]

static unsigned long middle_capacity = 1;
static bool cap_from_dt = true;
static u32 *raw_capacity;
static bool cap_parsing_failed;
static u32 capacity_scale;

static int __init parse_cpu_capacity(struct device_node *cpu_node, int cpu)
{
        int ret = 1;
        u32 cpu_capacity;

        if (cap_parsing_failed)
                return !ret;

        ret = of_property_read_u32(cpu_node,
                                   "capacity-dmips-mhz",
                                   &cpu_capacity);
        if (!ret) {
                if (!raw_capacity) {
                        raw_capacity = kcalloc(num_possible_cpus(),
                                               sizeof(*raw_capacity),
                                               GFP_KERNEL);
                        if (!raw_capacity) {
                                pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
                                cap_parsing_failed = true;
                                return !ret;
                        }
                }
                capacity_scale = max(cpu_capacity, capacity_scale);
                raw_capacity[cpu] = cpu_capacity;
                pr_debug("cpu_capacity: %s cpu_capacity=%u (raw)\n",
                        cpu_node->full_name, raw_capacity[cpu]);
        } else {
                if (raw_capacity) {
                        pr_err("cpu_capacity: missing %s raw capacity\n",
                                cpu_node->full_name);
                        pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
                }
                cap_parsing_failed = true;
                kfree(raw_capacity);
        }

        return !ret;
}

static void normalize_cpu_capacity(void)
{
        u64 capacity;
        int cpu;

        if (!raw_capacity || cap_parsing_failed)
                return;

        pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
        mutex_lock(&cpu_scale_mutex);
        for_each_possible_cpu(cpu) {
                capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
                        / capacity_scale;
                set_capacity_scale(cpu, capacity);
                pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
                        cpu, arch_scale_cpu_capacity(NULL, cpu));
        }
        mutex_unlock(&cpu_scale_mutex);
}

#ifdef CONFIG_CPU_FREQ
static cpumask_var_t cpus_to_visit;
static bool cap_parsing_done;
static void parsing_done_workfn(struct work_struct *work);
static DECLARE_WORK(parsing_done_work, parsing_done_workfn);

static int
init_cpu_capacity_callback(struct notifier_block *nb,
                           unsigned long val,
                           void *data)
{
        struct cpufreq_policy *policy = data;
        int cpu;

        if (cap_parsing_failed || cap_parsing_done)
                return 0;

        switch (val) {
        case CPUFREQ_NOTIFY:
                pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
                                cpumask_pr_args(policy->related_cpus),
                                cpumask_pr_args(cpus_to_visit));
                cpumask_andnot(cpus_to_visit,
                               cpus_to_visit,
                               policy->related_cpus);
                for_each_cpu(cpu, policy->related_cpus) {
                        raw_capacity[cpu] = arch_scale_cpu_capacity(NULL, cpu) *
                                            policy->cpuinfo.max_freq / 1000UL;
                        capacity_scale = max(raw_capacity[cpu], capacity_scale);
                }
                if (cpumask_empty(cpus_to_visit)) {
                        normalize_cpu_capacity();
                        kfree(raw_capacity);
                        pr_debug("cpu_capacity: parsing done\n");
                        cap_parsing_done = true;
                        schedule_work(&parsing_done_work);
                }
        }
        return 0;
}

static struct notifier_block init_cpu_capacity_notifier = {
        .notifier_call = init_cpu_capacity_callback,
};

static int __init register_cpufreq_notifier(void)
{
        if (cap_parsing_failed)
                return -EINVAL;

        if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
                pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
                return -ENOMEM;
        }
        cpumask_copy(cpus_to_visit, cpu_possible_mask);

        return cpufreq_register_notifier(&init_cpu_capacity_notifier,
                                         CPUFREQ_POLICY_NOTIFIER);
}
core_initcall(register_cpufreq_notifier);

static void parsing_done_workfn(struct work_struct *work)
{
        cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
                                         CPUFREQ_POLICY_NOTIFIER);
}

#else
static int __init free_raw_capacity(void)
{
        kfree(raw_capacity);

        return 0;
}
core_initcall(free_raw_capacity);
#endif

/*
 * Iterate all CPUs' descriptor in DT and compute the efficiency
 * (as per table_efficiency). Also calculate a middle efficiency
 * as close as possible to  (max{eff_i} - min{eff_i}) / 2
 * This is later used to scale the cpu_capacity field such that an
 * 'average' CPU is of middle capacity. Also see the comments near
 * table_efficiency[] and update_cpu_capacity().
 */
static void __init parse_dt_topology(void)
{
        const struct cpu_efficiency *cpu_eff;
        struct device_node *cn = NULL;
        unsigned long min_capacity = ULONG_MAX;
        unsigned long max_capacity = 0;
        unsigned long capacity = 0;
        int cpu = 0;

        __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity),
                                 GFP_NOWAIT);

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

        for_each_possible_cpu(cpu) {
                const u32 *rate;
                int len;

                /* too early to use cpu->of_node */
                cn = of_get_cpu_node(cpu, NULL);
                if (!cn) {
                        pr_err("missing device node for CPU %d\n", cpu);
                        continue;
                }

                if (parse_cpu_capacity(cn, cpu)) {
                        of_node_put(cn);
                        continue;
                }

                cap_from_dt = false;

                for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)
                        if (of_device_is_compatible(cn, cpu_eff->compatible))
                                break;

                if (cpu_eff->compatible == NULL)
                        continue;

                rate = of_get_property(cn, "clock-frequency", &len);
                if (!rate || len != 4) {
                        pr_err("%s missing clock-frequency property\n",
                                cn->full_name);
                        continue;
                }

                capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;

                /* Save min capacity of the system */
                if (capacity < min_capacity)
                        min_capacity = capacity;

                /* Save max capacity of the system */
                if (capacity > max_capacity)
                        max_capacity = capacity;

                cpu_capacity(cpu) = capacity;
        }

        /* If min and max capacities are equals, we bypass the update of the
         * cpu_scale because all CPUs have the same capacity. Otherwise, we
         * compute a middle_capacity factor that will ensure that the capacity
         * of an 'average' CPU of the system will be as close as possible to
         * SCHED_CAPACITY_SCALE, which is the default value, but with the
         * constraint explained near table_efficiency[].
         */
        if (4*max_capacity < (3*(max_capacity + min_capacity)))
                middle_capacity = (min_capacity + max_capacity)
                                >> (SCHED_CAPACITY_SHIFT+1);
        else
                middle_capacity = ((max_capacity / 3)
                                >> (SCHED_CAPACITY_SHIFT-1)) + 1;

        if (cap_from_dt && !cap_parsing_failed)
                normalize_cpu_capacity();
}

/*
 * Look for a customed capacity of a CPU in the cpu_capacity table during the
 * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
 * function returns directly for SMP system.
 */
static void update_cpu_capacity(unsigned int cpu)
{
        if (!cpu_capacity(cpu) || cap_from_dt)
                return;

        set_capacity_scale(cpu, cpu_capacity(cpu) / middle_capacity);

        pr_info("CPU%u: update cpu_capacity %lu\n",
                cpu, arch_scale_cpu_capacity(NULL, cpu));
}

#else
static inline void parse_dt_topology(void) {}
static inline void update_cpu_capacity(unsigned int cpuid) {}
#endif

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

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

/*
 * The current assumption is that we can power gate each core independently.
 * This will be superseded by DT binding once available.
 */
const struct cpumask *cpu_corepower_mask(int cpu)
{
        return &cpu_topology[cpu].thread_sibling;
}

static void update_siblings_masks(unsigned int cpuid)
{
        struct cputopo_arm *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->socket_id != cpu_topo->socket_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);
        }
        smp_wmb();
}

/*
 * store_cpu_topology is called at boot when only one cpu is running
 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
 * which prevents simultaneous write access to cpu_topology array
 */
void store_cpu_topology(unsigned int cpuid)
{
        struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
        unsigned int mpidr;

        /* If the cpu topology has been already set, just return */
        if (cpuid_topo->core_id != -1)
                return;

        mpidr = read_cpuid_mpidr();

        /* create cpu topology mapping */
        if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
                /*
                 * This is a multiprocessor system
                 * multiprocessor format & multiprocessor mode field are set
                 */

                if (mpidr & MPIDR_MT_BITMASK) {
                        /* core performance interdependency */
                        cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
                        cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
                        cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 2);
                } else {
                        /* largely independent cores */
                        cpuid_topo->thread_id = -1;
                        cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
                        cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
                }
        } else {
                /*
                 * This is an uniprocessor system
                 * we are in multiprocessor format but uniprocessor system
                 * or in the old uniprocessor format
                 */
                cpuid_topo->thread_id = -1;
                cpuid_topo->core_id = 0;
                cpuid_topo->socket_id = -1;
        }

        update_siblings_masks(cpuid);

        update_cpu_capacity(cpuid);

        pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
                cpuid, cpu_topology[cpuid].thread_id,
                cpu_topology[cpuid].core_id,
                cpu_topology[cpuid].socket_id, mpidr);
}

static inline int cpu_corepower_flags(void)
{
        return SD_SHARE_PKG_RESOURCES  | SD_SHARE_POWERDOMAIN;
}

static struct sched_domain_topology_level arm_topology[] = {
#ifdef CONFIG_SCHED_MC
        { cpu_corepower_mask, cpu_corepower_flags, SD_INIT_NAME(GMC) },
        { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
#endif
        { cpu_cpu_mask, SD_INIT_NAME(DIE) },
        { NULL, },
};

/*
 * init_cpu_topology is called at boot when only one cpu is running
 * which prevent simultaneous write access to cpu_topology array
 */
void __init init_cpu_topology(void)
{
        unsigned int cpu;

        /* init core mask and capacity */
        for_each_possible_cpu(cpu) {
                struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);

                cpu_topo->thread_id = -1;
                cpu_topo->core_id =  -1;
                cpu_topo->socket_id = -1;
                cpumask_clear(&cpu_topo->core_sibling);
                cpumask_clear(&cpu_topo->thread_sibling);
        }
        smp_wmb();

        parse_dt_topology();

        /* Set scheduler topology descriptor */
        set_sched_topology(arm_topology);
}