v4.19.13 snapshot.
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
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+++ b/arch/arm/kernel/topology.c
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+/*
+ * 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/arch_topology.h>
+#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.
+ */
+
+#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;
+
+/*
+ * 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 (topology_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("%pOF missing clock-frequency property\n", cn);
+ 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)
+ topology_normalize_cpu_scale();
+}
+
+/*
+ * 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;
+
+ topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity);
+
+ pr_info("CPU%u: update cpu_capacity %lu\n",
+ cpu, topology_get_cpu_scale(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);
+}