Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1877 insertions, 0 deletions

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
new file mode 100644
index 000000000..56d82f7f9
--- /dev/null
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -0,0 +1,1877 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * In-Memory Collection (IMC) Performance Monitor counter support.
+ *
+ * Copyright (C) 2017 Madhavan Srinivasan, IBM Corporation.
+ *           (C) 2017 Anju T Sudhakar, IBM Corporation.
+ *           (C) 2017 Hemant K Shaw, IBM Corporation.
+ */
+#include <linux/of.h>
+#include <linux/perf_event.h>
+#include <linux/slab.h>
+#include <asm/opal.h>
+#include <asm/imc-pmu.h>
+#include <asm/cputhreads.h>
+#include <asm/smp.h>
+#include <linux/string.h>
+#include <linux/spinlock.h>
+
+/* Nest IMC data structures and variables */
+
+/*
+ * Used to avoid races in counting the nest-pmu units during hotplug
+ * register and unregister
+ */
+static DEFINE_MUTEX(nest_init_lock);
+static DEFINE_PER_CPU(struct imc_pmu_ref *, local_nest_imc_refc);
+static struct imc_pmu **per_nest_pmu_arr;
+static cpumask_t nest_imc_cpumask;
+static struct imc_pmu_ref *nest_imc_refc;
+static int nest_pmus;
+
+/* Core IMC data structures and variables */
+
+static cpumask_t core_imc_cpumask;
+static struct imc_pmu_ref *core_imc_refc;
+static struct imc_pmu *core_imc_pmu;
+
+/* Thread IMC data structures and variables */
+
+static DEFINE_PER_CPU(u64 *, thread_imc_mem);
+static struct imc_pmu *thread_imc_pmu;
+static int thread_imc_mem_size;
+
+/* Trace IMC data structures */
+static DEFINE_PER_CPU(u64 *, trace_imc_mem);
+static struct imc_pmu_ref *trace_imc_refc;
+static int trace_imc_mem_size;
+
+/*
+ * Global data structure used to avoid races between thread,
+ * core and trace-imc
+ */
+static struct imc_pmu_ref imc_global_refc = {
+	.lock = __SPIN_LOCK_UNLOCKED(imc_global_refc.lock),
+	.id = 0,
+	.refc = 0,
+};
+
+static struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
+{
+	return container_of(event->pmu, struct imc_pmu, pmu);
+}
+
+PMU_FORMAT_ATTR(event, "config:0-61");
+PMU_FORMAT_ATTR(offset, "config:0-31");
+PMU_FORMAT_ATTR(rvalue, "config:32");
+PMU_FORMAT_ATTR(mode, "config:33-40");
+static struct attribute *imc_format_attrs[] = {
+	&format_attr_event.attr,
+	&format_attr_offset.attr,
+	&format_attr_rvalue.attr,
+	&format_attr_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group imc_format_group = {
+	.name = "format",
+	.attrs = imc_format_attrs,
+};
+
+/* Format attribute for imc trace-mode */
+PMU_FORMAT_ATTR(cpmc_reserved, "config:0-19");
+PMU_FORMAT_ATTR(cpmc_event, "config:20-27");
+PMU_FORMAT_ATTR(cpmc_samplesel, "config:28-29");
+PMU_FORMAT_ATTR(cpmc_load, "config:30-61");
+static struct attribute *trace_imc_format_attrs[] = {
+	&format_attr_event.attr,
+	&format_attr_cpmc_reserved.attr,
+	&format_attr_cpmc_event.attr,
+	&format_attr_cpmc_samplesel.attr,
+	&format_attr_cpmc_load.attr,
+	NULL,
+};
+
+static const struct attribute_group trace_imc_format_group = {
+.name = "format",
+.attrs = trace_imc_format_attrs,
+};
+
+/* Get the cpumask printed to a buffer "buf" */
+static ssize_t imc_pmu_cpumask_get_attr(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+	struct imc_pmu *imc_pmu = container_of(pmu, struct imc_pmu, pmu);
+	cpumask_t *active_mask;
+
+	switch(imc_pmu->domain){
+	case IMC_DOMAIN_NEST:
+		active_mask = &nest_imc_cpumask;
+		break;
+	case IMC_DOMAIN_CORE:
+		active_mask = &core_imc_cpumask;
+		break;
+	default:
+		return 0;
+	}
+
+	return cpumap_print_to_pagebuf(true, buf, active_mask);
+}
+
+static DEVICE_ATTR(cpumask, S_IRUGO, imc_pmu_cpumask_get_attr, NULL);
+
+static struct attribute *imc_pmu_cpumask_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL,
+};
+
+static const struct attribute_group imc_pmu_cpumask_attr_group = {
+	.attrs = imc_pmu_cpumask_attrs,
+};
+
+/* device_str_attr_create : Populate event "name" and string "str" in attribute */
+static struct attribute *device_str_attr_create(const char *name, const char *str)
+{
+	struct perf_pmu_events_attr *attr;
+
+	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+	if (!attr)
+		return NULL;
+	sysfs_attr_init(&attr->attr.attr);
+
+	attr->event_str = str;
+	attr->attr.attr.name = name;
+	attr->attr.attr.mode = 0444;
+	attr->attr.show = perf_event_sysfs_show;
+
+	return &attr->attr.attr;
+}
+
+static int imc_parse_event(struct device_node *np, const char *scale,
+				  const char *unit, const char *prefix,
+				  u32 base, struct imc_events *event)
+{
+	const char *s;
+	u32 reg;
+
+	if (of_property_read_u32(np, "reg", &reg))
+		goto error;
+	/* Add the base_reg value to the "reg" */
+	event->value = base + reg;
+
+	if (of_property_read_string(np, "event-name", &s))
+		goto error;
+
+	event->name = kasprintf(GFP_KERNEL, "%s%s", prefix, s);
+	if (!event->name)
+		goto error;
+
+	if (of_property_read_string(np, "scale", &s))
+		s = scale;
+
+	if (s) {
+		event->scale = kstrdup(s, GFP_KERNEL);
+		if (!event->scale)
+			goto error;
+	}
+
+	if (of_property_read_string(np, "unit", &s))
+		s = unit;
+
+	if (s) {
+		event->unit = kstrdup(s, GFP_KERNEL);
+		if (!event->unit)
+			goto error;
+	}
+
+	return 0;
+error:
+	kfree(event->unit);
+	kfree(event->scale);
+	kfree(event->name);
+	return -EINVAL;
+}
+
+/*
+ * imc_free_events: Function to cleanup the events list, having
+ * 		    "nr_entries".
+ */
+static void imc_free_events(struct imc_events *events, int nr_entries)
+{
+	int i;
+
+	/* Nothing to clean, return */
+	if (!events)
+		return;
+	for (i = 0; i < nr_entries; i++) {
+		kfree(events[i].unit);
+		kfree(events[i].scale);
+		kfree(events[i].name);
+	}
+
+	kfree(events);
+}
+
+/*
+ * update_events_in_group: Update the "events" information in an attr_group
+ *                         and assign the attr_group to the pmu "pmu".
+ */
+static int update_events_in_group(struct device_node *node, struct imc_pmu *pmu)
+{
+	struct attribute_group *attr_group;
+	struct attribute **attrs, *dev_str;
+	struct device_node *np, *pmu_events;
+	u32 handle, base_reg;
+	int i = 0, j = 0, ct, ret;
+	const char *prefix, *g_scale, *g_unit;
+	const char *ev_val_str, *ev_scale_str, *ev_unit_str;
+
+	if (!of_property_read_u32(node, "events", &handle))
+		pmu_events = of_find_node_by_phandle(handle);
+	else
+		return 0;
+
+	/* Did not find any node with a given phandle */
+	if (!pmu_events)
+		return 0;
+
+	/* Get a count of number of child nodes */
+	ct = of_get_child_count(pmu_events);
+
+	/* Get the event prefix */
+	if (of_property_read_string(node, "events-prefix", &prefix)) {
+		of_node_put(pmu_events);
+		return 0;
+	}
+
+	/* Get a global unit and scale data if available */
+	if (of_property_read_string(node, "scale", &g_scale))
+		g_scale = NULL;
+
+	if (of_property_read_string(node, "unit", &g_unit))
+		g_unit = NULL;
+
+	/* "reg" property gives out the base offset of the counters data */
+	of_property_read_u32(node, "reg", &base_reg);
+
+	/* Allocate memory for the events */
+	pmu->events = kcalloc(ct, sizeof(struct imc_events), GFP_KERNEL);
+	if (!pmu->events) {
+		of_node_put(pmu_events);
+		return -ENOMEM;
+	}
+
+	ct = 0;
+	/* Parse the events and update the struct */
+	for_each_child_of_node(pmu_events, np) {
+		ret = imc_parse_event(np, g_scale, g_unit, prefix, base_reg, &pmu->events[ct]);
+		if (!ret)
+			ct++;
+	}
+
+	of_node_put(pmu_events);
+
+	/* Allocate memory for attribute group */
+	attr_group = kzalloc(sizeof(*attr_group), GFP_KERNEL);
+	if (!attr_group) {
+		imc_free_events(pmu->events, ct);
+		return -ENOMEM;
+	}
+
+	/*
+	 * Allocate memory for attributes.
+	 * Since we have count of events for this pmu, we also allocate
+	 * memory for the scale and unit attribute for now.
+	 * "ct" has the total event structs added from the events-parent node.
+	 * So allocate three times the "ct" (this includes event, event_scale and
+	 * event_unit).
+	 */
+	attrs = kcalloc(((ct * 3) + 1), sizeof(struct attribute *), GFP_KERNEL);
+	if (!attrs) {
+		kfree(attr_group);
+		imc_free_events(pmu->events, ct);
+		return -ENOMEM;
+	}
+
+	attr_group->name = "events";
+	attr_group->attrs = attrs;
+	do {
+		ev_val_str = kasprintf(GFP_KERNEL, "event=0x%x", pmu->events[i].value);
+		if (!ev_val_str)
+			continue;
+		dev_str = device_str_attr_create(pmu->events[i].name, ev_val_str);
+		if (!dev_str)
+			continue;
+
+		attrs[j++] = dev_str;
+		if (pmu->events[i].scale) {
+			ev_scale_str = kasprintf(GFP_KERNEL, "%s.scale", pmu->events[i].name);
+			if (!ev_scale_str)
+				continue;
+			dev_str = device_str_attr_create(ev_scale_str, pmu->events[i].scale);
+			if (!dev_str)
+				continue;
+
+			attrs[j++] = dev_str;
+		}
+
+		if (pmu->events[i].unit) {
+			ev_unit_str = kasprintf(GFP_KERNEL, "%s.unit", pmu->events[i].name);
+			if (!ev_unit_str)
+				continue;
+			dev_str = device_str_attr_create(ev_unit_str, pmu->events[i].unit);
+			if (!dev_str)
+				continue;
+
+			attrs[j++] = dev_str;
+		}
+	} while (++i < ct);
+
+	/* Save the event attribute */
+	pmu->attr_groups[IMC_EVENT_ATTR] = attr_group;
+
+	return 0;
+}
+
+/* get_nest_pmu_ref: Return the imc_pmu_ref struct for the given node */
+static struct imc_pmu_ref *get_nest_pmu_ref(int cpu)
+{
+	return per_cpu(local_nest_imc_refc, cpu);
+}
+
+static void nest_change_cpu_context(int old_cpu, int new_cpu)
+{
+	struct imc_pmu **pn = per_nest_pmu_arr;
+
+	if (old_cpu < 0 || new_cpu < 0)
+		return;
+
+	while (*pn) {
+		perf_pmu_migrate_context(&(*pn)->pmu, old_cpu, new_cpu);
+		pn++;
+	}
+}
+
+static int ppc_nest_imc_cpu_offline(unsigned int cpu)
+{
+	int nid, target = -1;
+	const struct cpumask *l_cpumask;
+	struct imc_pmu_ref *ref;
+
+	/*
+	 * Check in the designated list for this cpu. Dont bother
+	 * if not one of them.
+	 */
+	if (!cpumask_test_and_clear_cpu(cpu, &nest_imc_cpumask))
+		return 0;
+
+	/*
+	 * Check whether nest_imc is registered. We could end up here if the
+	 * cpuhotplug callback registration fails. i.e, callback invokes the
+	 * offline path for all successfully registered nodes. At this stage,
+	 * nest_imc pmu will not be registered and we should return here.
+	 *
+	 * We return with a zero since this is not an offline failure. And
+	 * cpuhp_setup_state() returns the actual failure reason to the caller,
+	 * which in turn will call the cleanup routine.
+	 */
+	if (!nest_pmus)
+		return 0;
+
+	/*
+	 * Now that this cpu is one of the designated,
+	 * find a next cpu a) which is online and b) in same chip.
+	 */
+	nid = cpu_to_node(cpu);
+	l_cpumask = cpumask_of_node(nid);
+	target = cpumask_last(l_cpumask);
+
+	/*
+	 * If this(target) is the last cpu in the cpumask for this chip,
+	 * check for any possible online cpu in the chip.
+	 */
+	if (unlikely(target == cpu))
+		target = cpumask_any_but(l_cpumask, cpu);
+
+	/*
+	 * Update the cpumask with the target cpu and
+	 * migrate the context if needed
+	 */
+	if (target >= 0 && target < nr_cpu_ids) {
+		cpumask_set_cpu(target, &nest_imc_cpumask);
+		nest_change_cpu_context(cpu, target);
+	} else {
+		opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+				       get_hard_smp_processor_id(cpu));
+		/*
+		 * If this is the last cpu in this chip then, skip the reference
+		 * count lock and make the reference count on this chip zero.
+		 */
+		ref = get_nest_pmu_ref(cpu);
+		if (!ref)
+			return -EINVAL;
+
+		ref->refc = 0;
+	}
+	return 0;
+}
+
+static int ppc_nest_imc_cpu_online(unsigned int cpu)
+{
+	const struct cpumask *l_cpumask;
+	static struct cpumask tmp_mask;
+	int res;
+
+	/* Get the cpumask of this node */
+	l_cpumask = cpumask_of_node(cpu_to_node(cpu));
+
+	/*
+	 * If this is not the first online CPU on this node, then
+	 * just return.
+	 */
+	if (cpumask_and(&tmp_mask, l_cpumask, &nest_imc_cpumask))
+		return 0;
+
+	/*
+	 * If this is the first online cpu on this node
+	 * disable the nest counters by making an OPAL call.
+	 */
+	res = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+				     get_hard_smp_processor_id(cpu));
+	if (res)
+		return res;
+
+	/* Make this CPU the designated target for counter collection */
+	cpumask_set_cpu(cpu, &nest_imc_cpumask);
+	return 0;
+}
+
+static int nest_pmu_cpumask_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
+				 "perf/powerpc/imc:online",
+				 ppc_nest_imc_cpu_online,
+				 ppc_nest_imc_cpu_offline);
+}
+
+static void nest_imc_counters_release(struct perf_event *event)
+{
+	int rc, node_id;
+	struct imc_pmu_ref *ref;
+
+	if (event->cpu < 0)
+		return;
+
+	node_id = cpu_to_node(event->cpu);
+
+	/*
+	 * See if we need to disable the nest PMU.
+	 * If no events are currently in use, then we have to take a
+	 * lock to ensure that we don't race with another task doing
+	 * enable or disable the nest counters.
+	 */
+	ref = get_nest_pmu_ref(event->cpu);
+	if (!ref)
+		return;
+
+	/* Take the lock for this node and then decrement the reference count */
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		/*
+		 * The scenario where this is true is, when perf session is
+		 * started, followed by offlining of all cpus in a given node.
+		 *
+		 * In the cpuhotplug offline path, ppc_nest_imc_cpu_offline()
+		 * function set the ref->count to zero, if the cpu which is
+		 * about to offline is the last cpu in a given node and make
+		 * an OPAL call to disable the engine in that node.
+		 *
+		 */
+		spin_unlock(&ref->lock);
+		return;
+	}
+	ref->refc--;
+	if (ref->refc == 0) {
+		rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+					    get_hard_smp_processor_id(event->cpu));
+		if (rc) {
+			spin_unlock(&ref->lock);
+			pr_err("nest-imc: Unable to stop the counters for core %d\n", node_id);
+			return;
+		}
+	} else if (ref->refc < 0) {
+		WARN(1, "nest-imc: Invalid event reference count\n");
+		ref->refc = 0;
+	}
+	spin_unlock(&ref->lock);
+}
+
+static int nest_imc_event_init(struct perf_event *event)
+{
+	int chip_id, rc, node_id;
+	u32 l_config, config = event->attr.config;
+	struct imc_mem_info *pcni;
+	struct imc_pmu *pmu;
+	struct imc_pmu_ref *ref;
+	bool flag = false;
+
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/* Sampling not supported */
+	if (event->hw.sample_period)
+		return -EINVAL;
+
+	if (event->cpu < 0)
+		return -EINVAL;
+
+	pmu = imc_event_to_pmu(event);
+
+	/* Sanity check for config (event offset) */
+	if ((config & IMC_EVENT_OFFSET_MASK) > pmu->counter_mem_size)
+		return -EINVAL;
+
+	/*
+	 * Nest HW counter memory resides in a per-chip reserve-memory (HOMER).
+	 * Get the base memory address for this cpu.
+	 */
+	chip_id = cpu_to_chip_id(event->cpu);
+
+	/* Return, if chip_id is not valid */
+	if (chip_id < 0)
+		return -ENODEV;
+
+	pcni = pmu->mem_info;
+	do {
+		if (pcni->id == chip_id) {
+			flag = true;
+			break;
+		}
+		pcni++;
+	} while (pcni->vbase != 0);
+
+	if (!flag)
+		return -ENODEV;
+
+	/*
+	 * Add the event offset to the base address.
+	 */
+	l_config = config & IMC_EVENT_OFFSET_MASK;
+	event->hw.event_base = (u64)pcni->vbase + l_config;
+	node_id = cpu_to_node(event->cpu);
+
+	/*
+	 * Get the imc_pmu_ref struct for this node.
+	 * Take the lock and then increment the count of nest pmu events inited.
+	 */
+	ref = get_nest_pmu_ref(event->cpu);
+	if (!ref)
+		return -EINVAL;
+
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		rc = opal_imc_counters_start(OPAL_IMC_COUNTERS_NEST,
+					     get_hard_smp_processor_id(event->cpu));
+		if (rc) {
+			spin_unlock(&ref->lock);
+			pr_err("nest-imc: Unable to start the counters for node %d\n",
+									node_id);
+			return rc;
+		}
+	}
+	++ref->refc;
+	spin_unlock(&ref->lock);
+
+	event->destroy = nest_imc_counters_release;
+	return 0;
+}
+
+/*
+ * core_imc_mem_init : Initializes memory for the current core.
+ *
+ * Uses alloc_pages_node() and uses the returned address as an argument to
+ * an opal call to configure the pdbar. The address sent as an argument is
+ * converted to physical address before the opal call is made. This is the
+ * base address at which the core imc counters are populated.
+ */
+static int core_imc_mem_init(int cpu, int size)
+{
+	int nid, rc = 0, core_id = (cpu / threads_per_core);
+	struct imc_mem_info *mem_info;
+	struct page *page;
+
+	/*
+	 * alloc_pages_node() will allocate memory for core in the
+	 * local node only.
+	 */
+	nid = cpu_to_node(cpu);
+	mem_info = &core_imc_pmu->mem_info[core_id];
+	mem_info->id = core_id;
+
+	/* We need only vbase for core counters */
+	page = alloc_pages_node(nid,
+				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
+				__GFP_NOWARN, get_order(size));
+	if (!page)
+		return -ENOMEM;
+	mem_info->vbase = page_address(page);
+
+	core_imc_refc[core_id].id = core_id;
+	spin_lock_init(&core_imc_refc[core_id].lock);
+
+	rc = opal_imc_counters_init(OPAL_IMC_COUNTERS_CORE,
+				__pa((void *)mem_info->vbase),
+				get_hard_smp_processor_id(cpu));
+	if (rc) {
+		free_pages((u64)mem_info->vbase, get_order(size));
+		mem_info->vbase = NULL;
+	}
+
+	return rc;
+}
+
+static bool is_core_imc_mem_inited(int cpu)
+{
+	struct imc_mem_info *mem_info;
+	int core_id = (cpu / threads_per_core);
+
+	mem_info = &core_imc_pmu->mem_info[core_id];
+	if (!mem_info->vbase)
+		return false;
+
+	return true;
+}
+
+static int ppc_core_imc_cpu_online(unsigned int cpu)
+{
+	const struct cpumask *l_cpumask;
+	static struct cpumask tmp_mask;
+	int ret = 0;
+
+	/* Get the cpumask for this core */
+	l_cpumask = cpu_sibling_mask(cpu);
+
+	/* If a cpu for this core is already set, then, don't do anything */
+	if (cpumask_and(&tmp_mask, l_cpumask, &core_imc_cpumask))
+		return 0;
+
+	if (!is_core_imc_mem_inited(cpu)) {
+		ret = core_imc_mem_init(cpu, core_imc_pmu->counter_mem_size);
+		if (ret) {
+			pr_info("core_imc memory allocation for cpu %d failed\n", cpu);
+			return ret;
+		}
+	}
+
+	/* set the cpu in the mask */
+	cpumask_set_cpu(cpu, &core_imc_cpumask);
+	return 0;
+}
+
+static int ppc_core_imc_cpu_offline(unsigned int cpu)
+{
+	unsigned int core_id;
+	int ncpu;
+	struct imc_pmu_ref *ref;
+
+	/*
+	 * clear this cpu out of the mask, if not present in the mask,
+	 * don't bother doing anything.
+	 */
+	if (!cpumask_test_and_clear_cpu(cpu, &core_imc_cpumask))
+		return 0;
+
+	/*
+	 * Check whether core_imc is registered. We could end up here
+	 * if the cpuhotplug callback registration fails. i.e, callback
+	 * invokes the offline path for all successfully registered cpus.
+	 * At this stage, core_imc pmu will not be registered and we
+	 * should return here.
+	 *
+	 * We return with a zero since this is not an offline failure.
+	 * And cpuhp_setup_state() returns the actual failure reason
+	 * to the caller, which inturn will call the cleanup routine.
+	 */
+	if (!core_imc_pmu->pmu.event_init)
+		return 0;
+
+	/* Find any online cpu in that core except the current "cpu" */
+	ncpu = cpumask_last(cpu_sibling_mask(cpu));
+
+	if (unlikely(ncpu == cpu))
+		ncpu = cpumask_any_but(cpu_sibling_mask(cpu), cpu);
+
+	if (ncpu >= 0 && ncpu < nr_cpu_ids) {
+		cpumask_set_cpu(ncpu, &core_imc_cpumask);
+		perf_pmu_migrate_context(&core_imc_pmu->pmu, cpu, ncpu);
+	} else {
+		/*
+		 * If this is the last cpu in this core then skip taking reference
+		 * count lock for this core and directly zero "refc" for this core.
+		 */
+		opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
+				       get_hard_smp_processor_id(cpu));
+		core_id = cpu / threads_per_core;
+		ref = &core_imc_refc[core_id];
+		if (!ref)
+			return -EINVAL;
+
+		ref->refc = 0;
+		/*
+		 * Reduce the global reference count, if this is the
+		 * last cpu in this core and core-imc event running
+		 * in this cpu.
+		 */
+		spin_lock(&imc_global_refc.lock);
+		if (imc_global_refc.id == IMC_DOMAIN_CORE)
+			imc_global_refc.refc--;
+
+		spin_unlock(&imc_global_refc.lock);
+	}
+	return 0;
+}
+
+static int core_imc_pmu_cpumask_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
+				 "perf/powerpc/imc_core:online",
+				 ppc_core_imc_cpu_online,
+				 ppc_core_imc_cpu_offline);
+}
+
+static void reset_global_refc(struct perf_event *event)
+{
+		spin_lock(&imc_global_refc.lock);
+		imc_global_refc.refc--;
+
+		/*
+		 * If no other thread is running any
+		 * event for this domain(thread/core/trace),
+		 * set the global id to zero.
+		 */
+		if (imc_global_refc.refc <= 0) {
+			imc_global_refc.refc = 0;
+			imc_global_refc.id = 0;
+		}
+		spin_unlock(&imc_global_refc.lock);
+}
+
+static void core_imc_counters_release(struct perf_event *event)
+{
+	int rc, core_id;
+	struct imc_pmu_ref *ref;
+
+	if (event->cpu < 0)
+		return;
+	/*
+	 * See if we need to disable the IMC PMU.
+	 * If no events are currently in use, then we have to take a
+	 * lock to ensure that we don't race with another task doing
+	 * enable or disable the core counters.
+	 */
+	core_id = event->cpu / threads_per_core;
+
+	/* Take the lock and decrement the refernce count for this core */
+	ref = &core_imc_refc[core_id];
+	if (!ref)
+		return;
+
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		/*
+		 * The scenario where this is true is, when perf session is
+		 * started, followed by offlining of all cpus in a given core.
+		 *
+		 * In the cpuhotplug offline path, ppc_core_imc_cpu_offline()
+		 * function set the ref->count to zero, if the cpu which is
+		 * about to offline is the last cpu in a given core and make
+		 * an OPAL call to disable the engine in that core.
+		 *
+		 */
+		spin_unlock(&ref->lock);
+		return;
+	}
+	ref->refc--;
+	if (ref->refc == 0) {
+		rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
+					    get_hard_smp_processor_id(event->cpu));
+		if (rc) {
+			spin_unlock(&ref->lock);
+			pr_err("IMC: Unable to stop the counters for core %d\n", core_id);
+			return;
+		}
+	} else if (ref->refc < 0) {
+		WARN(1, "core-imc: Invalid event reference count\n");
+		ref->refc = 0;
+	}
+	spin_unlock(&ref->lock);
+
+	reset_global_refc(event);
+}
+
+static int core_imc_event_init(struct perf_event *event)
+{
+	int core_id, rc;
+	u64 config = event->attr.config;
+	struct imc_mem_info *pcmi;
+	struct imc_pmu *pmu;
+	struct imc_pmu_ref *ref;
+
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/* Sampling not supported */
+	if (event->hw.sample_period)
+		return -EINVAL;
+
+	if (event->cpu < 0)
+		return -EINVAL;
+
+	event->hw.idx = -1;
+	pmu = imc_event_to_pmu(event);
+
+	/* Sanity check for config (event offset) */
+	if (((config & IMC_EVENT_OFFSET_MASK) > pmu->counter_mem_size))
+		return -EINVAL;
+
+	if (!is_core_imc_mem_inited(event->cpu))
+		return -ENODEV;
+
+	core_id = event->cpu / threads_per_core;
+	pcmi = &core_imc_pmu->mem_info[core_id];
+	if ((!pcmi->vbase))
+		return -ENODEV;
+
+	ref = &core_imc_refc[core_id];
+	if (!ref)
+		return -EINVAL;
+
+	/*
+	 * Core pmu units are enabled only when it is used.
+	 * See if this is triggered for the first time.
+	 * If yes, take the lock and enable the core counters.
+	 * If not, just increment the count in core_imc_refc struct.
+	 */
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		rc = opal_imc_counters_start(OPAL_IMC_COUNTERS_CORE,
+					     get_hard_smp_processor_id(event->cpu));
+		if (rc) {
+			spin_unlock(&ref->lock);
+			pr_err("core-imc: Unable to start the counters for core %d\n",
+									core_id);
+			return rc;
+		}
+	}
+	++ref->refc;
+	spin_unlock(&ref->lock);
+
+	/*
+	 * Since the system can run either in accumulation or trace-mode
+	 * of IMC at a time, core-imc events are allowed only if no other
+	 * trace/thread imc events are enabled/monitored.
+	 *
+	 * Take the global lock, and check the refc.id
+	 * to know whether any other trace/thread imc
+	 * events are running.
+	 */
+	spin_lock(&imc_global_refc.lock);
+	if (imc_global_refc.id == 0 || imc_global_refc.id == IMC_DOMAIN_CORE) {
+		/*
+		 * No other trace/thread imc events are running in
+		 * the system, so set the refc.id to core-imc.
+		 */
+		imc_global_refc.id = IMC_DOMAIN_CORE;
+		imc_global_refc.refc++;
+	} else {
+		spin_unlock(&imc_global_refc.lock);
+		return -EBUSY;
+	}
+	spin_unlock(&imc_global_refc.lock);
+
+	event->hw.event_base = (u64)pcmi->vbase + (config & IMC_EVENT_OFFSET_MASK);
+	event->destroy = core_imc_counters_release;
+	return 0;
+}
+
+/*
+ * Allocates a page of memory for each of the online cpus, and load
+ * LDBAR with 0.
+ * The physical base address of the page allocated for a cpu will be
+ * written to the LDBAR for that cpu, when the thread-imc event
+ * is added.
+ *
+ * LDBAR Register Layout:
+ *
+ *  0          4         8         12        16        20        24        28
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *   | |       [   ]    [                   Counter Address [8:50]
+ *   | * Mode    |
+ *   |           * PB Scope
+ *   * Enable/Disable
+ *
+ *  32        36        40        44        48        52        56        60
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *           Counter Address [8:50]              ]
+ *
+ */
+static int thread_imc_mem_alloc(int cpu_id, int size)
+{
+	u64 *local_mem = per_cpu(thread_imc_mem, cpu_id);
+	int nid = cpu_to_node(cpu_id);
+
+	if (!local_mem) {
+		struct page *page;
+		/*
+		 * This case could happen only once at start, since we dont
+		 * free the memory in cpu offline path.
+		 */
+		page = alloc_pages_node(nid,
+				  GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
+				  __GFP_NOWARN, get_order(size));
+		if (!page)
+			return -ENOMEM;
+		local_mem = page_address(page);
+
+		per_cpu(thread_imc_mem, cpu_id) = local_mem;
+	}
+
+	mtspr(SPRN_LDBAR, 0);
+	return 0;
+}
+
+static int ppc_thread_imc_cpu_online(unsigned int cpu)
+{
+	return thread_imc_mem_alloc(cpu, thread_imc_mem_size);
+}
+
+static int ppc_thread_imc_cpu_offline(unsigned int cpu)
+{
+	/*
+	 * Set the bit 0 of LDBAR to zero.
+	 *
+	 * If bit 0 of LDBAR is unset, it will stop posting
+	 * the counter data to memory.
+	 * For thread-imc, bit 0 of LDBAR will be set to 1 in the
+	 * event_add function. So reset this bit here, to stop the updates
+	 * to memory in the cpu_offline path.
+	 */
+	mtspr(SPRN_LDBAR, (mfspr(SPRN_LDBAR) & (~(1UL << 63))));
+
+	/* Reduce the refc if thread-imc event running on this cpu */
+	spin_lock(&imc_global_refc.lock);
+	if (imc_global_refc.id == IMC_DOMAIN_THREAD)
+		imc_global_refc.refc--;
+	spin_unlock(&imc_global_refc.lock);
+
+	return 0;
+}
+
+static int thread_imc_cpu_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
+			  "perf/powerpc/imc_thread:online",
+			  ppc_thread_imc_cpu_online,
+			  ppc_thread_imc_cpu_offline);
+}
+
+static int thread_imc_event_init(struct perf_event *event)
+{
+	u32 config = event->attr.config;
+	struct task_struct *target;
+	struct imc_pmu *pmu;
+
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	if (!perfmon_capable())
+		return -EACCES;
+
+	/* Sampling not supported */
+	if (event->hw.sample_period)
+		return -EINVAL;
+
+	event->hw.idx = -1;
+	pmu = imc_event_to_pmu(event);
+
+	/* Sanity check for config offset */
+	if (((config & IMC_EVENT_OFFSET_MASK) > pmu->counter_mem_size))
+		return -EINVAL;
+
+	target = event->hw.target;
+	if (!target)
+		return -EINVAL;
+
+	spin_lock(&imc_global_refc.lock);
+	/*
+	 * Check if any other trace/core imc events are running in the
+	 * system, if not set the global id to thread-imc.
+	 */
+	if (imc_global_refc.id == 0 || imc_global_refc.id == IMC_DOMAIN_THREAD) {
+		imc_global_refc.id = IMC_DOMAIN_THREAD;
+		imc_global_refc.refc++;
+	} else {
+		spin_unlock(&imc_global_refc.lock);
+		return -EBUSY;
+	}
+	spin_unlock(&imc_global_refc.lock);
+
+	event->pmu->task_ctx_nr = perf_sw_context;
+	event->destroy = reset_global_refc;
+	return 0;
+}
+
+static bool is_thread_imc_pmu(struct perf_event *event)
+{
+	if (!strncmp(event->pmu->name, "thread_imc", strlen("thread_imc")))
+		return true;
+
+	return false;
+}
+
+static u64 * get_event_base_addr(struct perf_event *event)
+{
+	u64 addr;
+
+	if (is_thread_imc_pmu(event)) {
+		addr = (u64)per_cpu(thread_imc_mem, smp_processor_id());
+		return (u64 *)(addr + (event->attr.config & IMC_EVENT_OFFSET_MASK));
+	}
+
+	return (u64 *)event->hw.event_base;
+}
+
+static void thread_imc_pmu_start_txn(struct pmu *pmu,
+				     unsigned int txn_flags)
+{
+	if (txn_flags & ~PERF_PMU_TXN_ADD)
+		return;
+	perf_pmu_disable(pmu);
+}
+
+static void thread_imc_pmu_cancel_txn(struct pmu *pmu)
+{
+	perf_pmu_enable(pmu);
+}
+
+static int thread_imc_pmu_commit_txn(struct pmu *pmu)
+{
+	perf_pmu_enable(pmu);
+	return 0;
+}
+
+static u64 imc_read_counter(struct perf_event *event)
+{
+	u64 *addr, data;
+
+	/*
+	 * In-Memory Collection (IMC) counters are free flowing counters.
+	 * So we take a snapshot of the counter value on enable and save it
+	 * to calculate the delta at later stage to present the event counter
+	 * value.
+	 */
+	addr = get_event_base_addr(event);
+	data = be64_to_cpu(READ_ONCE(*addr));
+	local64_set(&event->hw.prev_count, data);
+
+	return data;
+}
+
+static void imc_event_update(struct perf_event *event)
+{
+	u64 counter_prev, counter_new, final_count;
+
+	counter_prev = local64_read(&event->hw.prev_count);
+	counter_new = imc_read_counter(event);
+	final_count = counter_new - counter_prev;
+
+	/* Update the delta to the event count */
+	local64_add(final_count, &event->count);
+}
+
+static void imc_event_start(struct perf_event *event, int flags)
+{
+	/*
+	 * In Memory Counters are free flowing counters. HW or the microcode
+	 * keeps adding to the counter offset in memory. To get event
+	 * counter value, we snapshot the value here and we calculate
+	 * delta at later point.
+	 */
+	imc_read_counter(event);
+}
+
+static void imc_event_stop(struct perf_event *event, int flags)
+{
+	/*
+	 * Take a snapshot and calculate the delta and update
+	 * the event counter values.
+	 */
+	imc_event_update(event);
+}
+
+static int imc_event_add(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_START)
+		imc_event_start(event, flags);
+
+	return 0;
+}
+
+static int thread_imc_event_add(struct perf_event *event, int flags)
+{
+	int core_id;
+	struct imc_pmu_ref *ref;
+	u64 ldbar_value, *local_mem = per_cpu(thread_imc_mem, smp_processor_id());
+
+	if (flags & PERF_EF_START)
+		imc_event_start(event, flags);
+
+	if (!is_core_imc_mem_inited(smp_processor_id()))
+		return -EINVAL;
+
+	core_id = smp_processor_id() / threads_per_core;
+	ldbar_value = ((u64)local_mem & THREAD_IMC_LDBAR_MASK) | THREAD_IMC_ENABLE;
+	mtspr(SPRN_LDBAR, ldbar_value);
+
+	/*
+	 * imc pmus are enabled only when it is used.
+	 * See if this is triggered for the first time.
+	 * If yes, take the lock and enable the counters.
+	 * If not, just increment the count in ref count struct.
+	 */
+	ref = &core_imc_refc[core_id];
+	if (!ref)
+		return -EINVAL;
+
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		if (opal_imc_counters_start(OPAL_IMC_COUNTERS_CORE,
+		    get_hard_smp_processor_id(smp_processor_id()))) {
+			spin_unlock(&ref->lock);
+			pr_err("thread-imc: Unable to start the counter\
+				for core %d\n", core_id);
+			return -EINVAL;
+		}
+	}
+	++ref->refc;
+	spin_unlock(&ref->lock);
+	return 0;
+}
+
+static void thread_imc_event_del(struct perf_event *event, int flags)
+{
+
+	int core_id;
+	struct imc_pmu_ref *ref;
+
+	core_id = smp_processor_id() / threads_per_core;
+	ref = &core_imc_refc[core_id];
+	if (!ref) {
+		pr_debug("imc: Failed to get event reference count\n");
+		return;
+	}
+
+	spin_lock(&ref->lock);
+	ref->refc--;
+	if (ref->refc == 0) {
+		if (opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
+		    get_hard_smp_processor_id(smp_processor_id()))) {
+			spin_unlock(&ref->lock);
+			pr_err("thread-imc: Unable to stop the counters\
+				for core %d\n", core_id);
+			return;
+		}
+	} else if (ref->refc < 0) {
+		ref->refc = 0;
+	}
+	spin_unlock(&ref->lock);
+
+	/* Set bit 0 of LDBAR to zero, to stop posting updates to memory */
+	mtspr(SPRN_LDBAR, (mfspr(SPRN_LDBAR) & (~(1UL << 63))));
+
+	/*
+	 * Take a snapshot and calculate the delta and update
+	 * the event counter values.
+	 */
+	imc_event_update(event);
+}
+
+/*
+ * Allocate a page of memory for each cpu, and load LDBAR with 0.
+ */
+static int trace_imc_mem_alloc(int cpu_id, int size)
+{
+	u64 *local_mem = per_cpu(trace_imc_mem, cpu_id);
+	int phys_id = cpu_to_node(cpu_id), rc = 0;
+	int core_id = (cpu_id / threads_per_core);
+
+	if (!local_mem) {
+		struct page *page;
+
+		page = alloc_pages_node(phys_id,
+				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
+				__GFP_NOWARN, get_order(size));
+		if (!page)
+			return -ENOMEM;
+		local_mem = page_address(page);
+		per_cpu(trace_imc_mem, cpu_id) = local_mem;
+
+		/* Initialise the counters for trace mode */
+		rc = opal_imc_counters_init(OPAL_IMC_COUNTERS_TRACE, __pa((void *)local_mem),
+					    get_hard_smp_processor_id(cpu_id));
+		if (rc) {
+			pr_info("IMC:opal init failed for trace imc\n");
+			return rc;
+		}
+	}
+
+	trace_imc_refc[core_id].id = core_id;
+	spin_lock_init(&trace_imc_refc[core_id].lock);
+
+	mtspr(SPRN_LDBAR, 0);
+	return 0;
+}
+
+static int ppc_trace_imc_cpu_online(unsigned int cpu)
+{
+	return trace_imc_mem_alloc(cpu, trace_imc_mem_size);
+}
+
+static int ppc_trace_imc_cpu_offline(unsigned int cpu)
+{
+	/*
+	 * No need to set bit 0 of LDBAR to zero, as
+	 * it is set to zero for imc trace-mode
+	 *
+	 * Reduce the refc if any trace-imc event running
+	 * on this cpu.
+	 */
+	spin_lock(&imc_global_refc.lock);
+	if (imc_global_refc.id == IMC_DOMAIN_TRACE)
+		imc_global_refc.refc--;
+	spin_unlock(&imc_global_refc.lock);
+
+	return 0;
+}
+
+static int trace_imc_cpu_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
+			  "perf/powerpc/imc_trace:online",
+			  ppc_trace_imc_cpu_online,
+			  ppc_trace_imc_cpu_offline);
+}
+
+static u64 get_trace_imc_event_base_addr(void)
+{
+	return (u64)per_cpu(trace_imc_mem, smp_processor_id());
+}
+
+/*
+ * Function to parse trace-imc data obtained
+ * and to prepare the perf sample.
+ */
+static int trace_imc_prepare_sample(struct trace_imc_data *mem,
+				    struct perf_sample_data *data,
+				    u64 *prev_tb,
+				    struct perf_event_header *header,
+				    struct perf_event *event)
+{
+	/* Sanity checks for a valid record */
+	if (be64_to_cpu(READ_ONCE(mem->tb1)) > *prev_tb)
+		*prev_tb = be64_to_cpu(READ_ONCE(mem->tb1));
+	else
+		return -EINVAL;
+
+	if ((be64_to_cpu(READ_ONCE(mem->tb1)) & IMC_TRACE_RECORD_TB1_MASK) !=
+			 be64_to_cpu(READ_ONCE(mem->tb2)))
+		return -EINVAL;
+
+	/* Prepare perf sample */
+	data->ip =  be64_to_cpu(READ_ONCE(mem->ip));
+	data->period = event->hw.last_period;
+
+	header->type = PERF_RECORD_SAMPLE;
+	header->size = sizeof(*header) + event->header_size;
+	header->misc = 0;
+
+	if (cpu_has_feature(CPU_FTR_ARCH_31)) {
+		switch (IMC_TRACE_RECORD_VAL_HVPR(be64_to_cpu(READ_ONCE(mem->val)))) {
+		case 0:/* when MSR HV and PR not set in the trace-record */
+			header->misc |= PERF_RECORD_MISC_GUEST_KERNEL;
+			break;
+		case 1: /* MSR HV is 0 and PR is 1 */
+			header->misc |= PERF_RECORD_MISC_GUEST_USER;
+			break;
+		case 2: /* MSR HV is 1 and PR is 0 */
+			header->misc |= PERF_RECORD_MISC_KERNEL;
+			break;
+		case 3: /* MSR HV is 1 and PR is 1 */
+			header->misc |= PERF_RECORD_MISC_USER;
+			break;
+		default:
+			pr_info("IMC: Unable to set the flag based on MSR bits\n");
+			break;
+		}
+	} else {
+		if (is_kernel_addr(data->ip))
+			header->misc |= PERF_RECORD_MISC_KERNEL;
+		else
+			header->misc |= PERF_RECORD_MISC_USER;
+	}
+	perf_event_header__init_id(header, data, event);
+
+	return 0;
+}
+
+static void dump_trace_imc_data(struct perf_event *event)
+{
+	struct trace_imc_data *mem;
+	int i, ret;
+	u64 prev_tb = 0;
+
+	mem = (struct trace_imc_data *)get_trace_imc_event_base_addr();
+	for (i = 0; i < (trace_imc_mem_size / sizeof(struct trace_imc_data));
+		i++, mem++) {
+		struct perf_sample_data data;
+		struct perf_event_header header;
+
+		ret = trace_imc_prepare_sample(mem, &data, &prev_tb, &header, event);
+		if (ret) /* Exit, if not a valid record */
+			break;
+		else {
+			/* If this is a valid record, create the sample */
+			struct perf_output_handle handle;
+
+			if (perf_output_begin(&handle, &data, event, header.size))
+				return;
+
+			perf_output_sample(&handle, &header, &data, event);
+			perf_output_end(&handle);
+		}
+	}
+}
+
+static int trace_imc_event_add(struct perf_event *event, int flags)
+{
+	int core_id = smp_processor_id() / threads_per_core;
+	struct imc_pmu_ref *ref = NULL;
+	u64 local_mem, ldbar_value;
+
+	/* Set trace-imc bit in ldbar and load ldbar with per-thread memory address */
+	local_mem = get_trace_imc_event_base_addr();
+	ldbar_value = ((u64)local_mem & THREAD_IMC_LDBAR_MASK) | TRACE_IMC_ENABLE;
+
+	/* trace-imc reference count */
+	if (trace_imc_refc)
+		ref = &trace_imc_refc[core_id];
+	if (!ref) {
+		pr_debug("imc: Failed to get the event reference count\n");
+		return -EINVAL;
+	}
+
+	mtspr(SPRN_LDBAR, ldbar_value);
+	spin_lock(&ref->lock);
+	if (ref->refc == 0) {
+		if (opal_imc_counters_start(OPAL_IMC_COUNTERS_TRACE,
+				get_hard_smp_processor_id(smp_processor_id()))) {
+			spin_unlock(&ref->lock);
+			pr_err("trace-imc: Unable to start the counters for core %d\n", core_id);
+			return -EINVAL;
+		}
+	}
+	++ref->refc;
+	spin_unlock(&ref->lock);
+	return 0;
+}
+
+static void trace_imc_event_read(struct perf_event *event)
+{
+	return;
+}
+
+static void trace_imc_event_stop(struct perf_event *event, int flags)
+{
+	u64 local_mem = get_trace_imc_event_base_addr();
+	dump_trace_imc_data(event);
+	memset((void *)local_mem, 0, sizeof(u64));
+}
+
+static void trace_imc_event_start(struct perf_event *event, int flags)
+{
+	return;
+}
+
+static void trace_imc_event_del(struct perf_event *event, int flags)
+{
+	int core_id = smp_processor_id() / threads_per_core;
+	struct imc_pmu_ref *ref = NULL;
+
+	if (trace_imc_refc)
+		ref = &trace_imc_refc[core_id];
+	if (!ref) {
+		pr_debug("imc: Failed to get event reference count\n");
+		return;
+	}
+
+	spin_lock(&ref->lock);
+	ref->refc--;
+	if (ref->refc == 0) {
+		if (opal_imc_counters_stop(OPAL_IMC_COUNTERS_TRACE,
+				get_hard_smp_processor_id(smp_processor_id()))) {
+			spin_unlock(&ref->lock);
+			pr_err("trace-imc: Unable to stop the counters for core %d\n", core_id);
+			return;
+		}
+	} else if (ref->refc < 0) {
+		ref->refc = 0;
+	}
+	spin_unlock(&ref->lock);
+
+	trace_imc_event_stop(event, flags);
+}
+
+static int trace_imc_event_init(struct perf_event *event)
+{
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	if (!perfmon_capable())
+		return -EACCES;
+
+	/* Return if this is a couting event */
+	if (event->attr.sample_period == 0)
+		return -ENOENT;
+
+	/*
+	 * Take the global lock, and make sure
+	 * no other thread is running any core/thread imc
+	 * events
+	 */
+	spin_lock(&imc_global_refc.lock);
+	if (imc_global_refc.id == 0 || imc_global_refc.id == IMC_DOMAIN_TRACE) {
+		/*
+		 * No core/thread imc events are running in the
+		 * system, so set the refc.id to trace-imc.
+		 */
+		imc_global_refc.id = IMC_DOMAIN_TRACE;
+		imc_global_refc.refc++;
+	} else {
+		spin_unlock(&imc_global_refc.lock);
+		return -EBUSY;
+	}
+	spin_unlock(&imc_global_refc.lock);
+
+	event->hw.idx = -1;
+
+	/*
+	 * There can only be a single PMU for perf_hw_context events which is assigned to
+	 * core PMU. Hence use "perf_sw_context" for trace_imc.
+	 */
+	event->pmu->task_ctx_nr = perf_sw_context;
+	event->destroy = reset_global_refc;
+	return 0;
+}
+
+/* update_pmu_ops : Populate the appropriate operations for "pmu" */
+static int update_pmu_ops(struct imc_pmu *pmu)
+{
+	pmu->pmu.task_ctx_nr = perf_invalid_context;
+	pmu->pmu.add = imc_event_add;
+	pmu->pmu.del = imc_event_stop;
+	pmu->pmu.start = imc_event_start;
+	pmu->pmu.stop = imc_event_stop;
+	pmu->pmu.read = imc_event_update;
+	pmu->pmu.attr_groups = pmu->attr_groups;
+	pmu->pmu.capabilities = PERF_PMU_CAP_NO_EXCLUDE;
+	pmu->attr_groups[IMC_FORMAT_ATTR] = &imc_format_group;
+
+	switch (pmu->domain) {
+	case IMC_DOMAIN_NEST:
+		pmu->pmu.event_init = nest_imc_event_init;
+		pmu->attr_groups[IMC_CPUMASK_ATTR] = &imc_pmu_cpumask_attr_group;
+		break;
+	case IMC_DOMAIN_CORE:
+		pmu->pmu.event_init = core_imc_event_init;
+		pmu->attr_groups[IMC_CPUMASK_ATTR] = &imc_pmu_cpumask_attr_group;
+		break;
+	case IMC_DOMAIN_THREAD:
+		pmu->pmu.event_init = thread_imc_event_init;
+		pmu->pmu.add = thread_imc_event_add;
+		pmu->pmu.del = thread_imc_event_del;
+		pmu->pmu.start_txn = thread_imc_pmu_start_txn;
+		pmu->pmu.cancel_txn = thread_imc_pmu_cancel_txn;
+		pmu->pmu.commit_txn = thread_imc_pmu_commit_txn;
+		break;
+	case IMC_DOMAIN_TRACE:
+		pmu->pmu.event_init = trace_imc_event_init;
+		pmu->pmu.add = trace_imc_event_add;
+		pmu->pmu.del = trace_imc_event_del;
+		pmu->pmu.start = trace_imc_event_start;
+		pmu->pmu.stop = trace_imc_event_stop;
+		pmu->pmu.read = trace_imc_event_read;
+		pmu->attr_groups[IMC_FORMAT_ATTR] = &trace_imc_format_group;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+/* init_nest_pmu_ref: Initialize the imc_pmu_ref struct for all the nodes */
+static int init_nest_pmu_ref(void)
+{
+	int nid, i, cpu;
+
+	nest_imc_refc = kcalloc(num_possible_nodes(), sizeof(*nest_imc_refc),
+								GFP_KERNEL);
+
+	if (!nest_imc_refc)
+		return -ENOMEM;
+
+	i = 0;
+	for_each_node(nid) {
+		/*
+		 * Take the lock to avoid races while tracking the number of
+		 * sessions using the chip's nest pmu units.
+		 */
+		spin_lock_init(&nest_imc_refc[i].lock);
+
+		/*
+		 * Loop to init the "id" with the node_id. Variable "i" initialized to
+		 * 0 and will be used as index to the array. "i" will not go off the
+		 * end of the array since the "for_each_node" loops for "N_POSSIBLE"
+		 * nodes only.
+		 */
+		nest_imc_refc[i++].id = nid;
+	}
+
+	/*
+	 * Loop to init the per_cpu "local_nest_imc_refc" with the proper
+	 * "nest_imc_refc" index. This makes get_nest_pmu_ref() alot simple.
+	 */
+	for_each_possible_cpu(cpu) {
+		nid = cpu_to_node(cpu);
+		for (i = 0; i < num_possible_nodes(); i++) {
+			if (nest_imc_refc[i].id == nid) {
+				per_cpu(local_nest_imc_refc, cpu) = &nest_imc_refc[i];
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+static void cleanup_all_core_imc_memory(void)
+{
+	int i, nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
+	struct imc_mem_info *ptr = core_imc_pmu->mem_info;
+	int size = core_imc_pmu->counter_mem_size;
+
+	/* mem_info will never be NULL */
+	for (i = 0; i < nr_cores; i++) {
+		if (ptr[i].vbase)
+			free_pages((u64)ptr[i].vbase, get_order(size));
+	}
+
+	kfree(ptr);
+	kfree(core_imc_refc);
+}
+
+static void thread_imc_ldbar_disable(void *dummy)
+{
+	/*
+	 * By setting 0th bit of LDBAR to zero, we disable thread-imc
+	 * updates to memory.
+	 */
+	mtspr(SPRN_LDBAR, (mfspr(SPRN_LDBAR) & (~(1UL << 63))));
+}
+
+void thread_imc_disable(void)
+{
+	on_each_cpu(thread_imc_ldbar_disable, NULL, 1);
+}
+
+static void cleanup_all_thread_imc_memory(void)
+{
+	int i, order = get_order(thread_imc_mem_size);
+
+	for_each_online_cpu(i) {
+		if (per_cpu(thread_imc_mem, i))
+			free_pages((u64)per_cpu(thread_imc_mem, i), order);
+
+	}
+}
+
+static void cleanup_all_trace_imc_memory(void)
+{
+	int i, order = get_order(trace_imc_mem_size);
+
+	for_each_online_cpu(i) {
+		if (per_cpu(trace_imc_mem, i))
+			free_pages((u64)per_cpu(trace_imc_mem, i), order);
+
+	}
+	kfree(trace_imc_refc);
+}
+
+/* Function to free the attr_groups which are dynamically allocated */
+static void imc_common_mem_free(struct imc_pmu *pmu_ptr)
+{
+	if (pmu_ptr->attr_groups[IMC_EVENT_ATTR])
+		kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs);
+	kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]);
+}
+
+/*
+ * Common function to unregister cpu hotplug callback and
+ * free the memory.
+ * TODO: Need to handle pmu unregistering, which will be
+ * done in followup series.
+ */
+static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
+{
+	if (pmu_ptr->domain == IMC_DOMAIN_NEST) {
+		mutex_lock(&nest_init_lock);
+		if (nest_pmus == 1) {
+			cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE);
+			kfree(nest_imc_refc);
+			kfree(per_nest_pmu_arr);
+			per_nest_pmu_arr = NULL;
+		}
+
+		if (nest_pmus > 0)
+			nest_pmus--;
+		mutex_unlock(&nest_init_lock);
+	}
+
+	/* Free core_imc memory */
+	if (pmu_ptr->domain == IMC_DOMAIN_CORE) {
+		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE);
+		cleanup_all_core_imc_memory();
+	}
+
+	/* Free thread_imc memory */
+	if (pmu_ptr->domain == IMC_DOMAIN_THREAD) {
+		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE);
+		cleanup_all_thread_imc_memory();
+	}
+
+	if (pmu_ptr->domain == IMC_DOMAIN_TRACE) {
+		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE);
+		cleanup_all_trace_imc_memory();
+	}
+}
+
+/*
+ * Function to unregister thread-imc if core-imc
+ * is not registered.
+ */
+void unregister_thread_imc(void)
+{
+	imc_common_cpuhp_mem_free(thread_imc_pmu);
+	imc_common_mem_free(thread_imc_pmu);
+	perf_pmu_unregister(&thread_imc_pmu->pmu);
+}
+
+/*
+ * imc_mem_init : Function to support memory allocation for core imc.
+ */
+static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,
+								int pmu_index)
+{
+	const char *s;
+	int nr_cores, cpu, res = -ENOMEM;
+
+	if (of_property_read_string(parent, "name", &s))
+		return -ENODEV;
+
+	switch (pmu_ptr->domain) {
+	case IMC_DOMAIN_NEST:
+		/* Update the pmu name */
+		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s_imc", "nest_", s);
+		if (!pmu_ptr->pmu.name)
+			goto err;
+
+		/* Needed for hotplug/migration */
+		if (!per_nest_pmu_arr) {
+			per_nest_pmu_arr = kcalloc(get_max_nest_dev() + 1,
+						sizeof(struct imc_pmu *),
+						GFP_KERNEL);
+			if (!per_nest_pmu_arr)
+				goto err;
+		}
+		per_nest_pmu_arr[pmu_index] = pmu_ptr;
+		break;
+	case IMC_DOMAIN_CORE:
+		/* Update the pmu name */
+		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
+		if (!pmu_ptr->pmu.name)
+			goto err;
+
+		nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
+		pmu_ptr->mem_info = kcalloc(nr_cores, sizeof(struct imc_mem_info),
+								GFP_KERNEL);
+
+		if (!pmu_ptr->mem_info)
+			goto err;
+
+		core_imc_refc = kcalloc(nr_cores, sizeof(struct imc_pmu_ref),
+								GFP_KERNEL);
+
+		if (!core_imc_refc) {
+			kfree(pmu_ptr->mem_info);
+			goto err;
+		}
+
+		core_imc_pmu = pmu_ptr;
+		break;
+	case IMC_DOMAIN_THREAD:
+		/* Update the pmu name */
+		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
+		if (!pmu_ptr->pmu.name)
+			goto err;
+
+		thread_imc_mem_size = pmu_ptr->counter_mem_size;
+		for_each_online_cpu(cpu) {
+			res = thread_imc_mem_alloc(cpu, pmu_ptr->counter_mem_size);
+			if (res) {
+				cleanup_all_thread_imc_memory();
+				goto err;
+			}
+		}
+
+		thread_imc_pmu = pmu_ptr;
+		break;
+	case IMC_DOMAIN_TRACE:
+		/* Update the pmu name */
+		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
+		if (!pmu_ptr->pmu.name)
+			return -ENOMEM;
+
+		nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
+		trace_imc_refc = kcalloc(nr_cores, sizeof(struct imc_pmu_ref),
+								GFP_KERNEL);
+		if (!trace_imc_refc)
+			return -ENOMEM;
+
+		trace_imc_mem_size = pmu_ptr->counter_mem_size;
+		for_each_online_cpu(cpu) {
+			res = trace_imc_mem_alloc(cpu, trace_imc_mem_size);
+			if (res) {
+				cleanup_all_trace_imc_memory();
+				goto err;
+			}
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+err:
+	return res;
+}
+
+/*
+ * init_imc_pmu : Setup and register the IMC pmu device.
+ *
+ * @parent:	Device tree unit node
+ * @pmu_ptr:	memory allocated for this pmu
+ * @pmu_idx:	Count of nest pmc registered
+ *
+ * init_imc_pmu() setup pmu cpumask and registers for a cpu hotplug callback.
+ * Handles failure cases and accordingly frees memory.
+ */
+int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_idx)
+{
+	int ret;
+
+	ret = imc_mem_init(pmu_ptr, parent, pmu_idx);
+	if (ret)
+		goto err_free_mem;
+
+	switch (pmu_ptr->domain) {
+	case IMC_DOMAIN_NEST:
+		/*
+		* Nest imc pmu need only one cpu per chip, we initialize the
+		* cpumask for the first nest imc pmu and use the same for the
+		* rest. To handle the cpuhotplug callback unregister, we track
+		* the number of nest pmus in "nest_pmus".
+		*/
+		mutex_lock(&nest_init_lock);
+		if (nest_pmus == 0) {
+			ret = init_nest_pmu_ref();
+			if (ret) {
+				mutex_unlock(&nest_init_lock);
+				kfree(per_nest_pmu_arr);
+				per_nest_pmu_arr = NULL;
+				goto err_free_mem;
+			}
+			/* Register for cpu hotplug notification. */
+			ret = nest_pmu_cpumask_init();
+			if (ret) {
+				mutex_unlock(&nest_init_lock);
+				kfree(nest_imc_refc);
+				kfree(per_nest_pmu_arr);
+				per_nest_pmu_arr = NULL;
+				goto err_free_mem;
+			}
+		}
+		nest_pmus++;
+		mutex_unlock(&nest_init_lock);
+		break;
+	case IMC_DOMAIN_CORE:
+		ret = core_imc_pmu_cpumask_init();
+		if (ret) {
+			cleanup_all_core_imc_memory();
+			goto err_free_mem;
+		}
+
+		break;
+	case IMC_DOMAIN_THREAD:
+		ret = thread_imc_cpu_init();
+		if (ret) {
+			cleanup_all_thread_imc_memory();
+			goto err_free_mem;
+		}
+
+		break;
+	case IMC_DOMAIN_TRACE:
+		ret = trace_imc_cpu_init();
+		if (ret) {
+			cleanup_all_trace_imc_memory();
+			goto err_free_mem;
+		}
+
+		break;
+	default:
+		return  -EINVAL;	/* Unknown domain */
+	}
+
+	ret = update_events_in_group(parent, pmu_ptr);
+	if (ret)
+		goto err_free_cpuhp_mem;
+
+	ret = update_pmu_ops(pmu_ptr);
+	if (ret)
+		goto err_free_cpuhp_mem;
+
+	ret = perf_pmu_register(&pmu_ptr->pmu, pmu_ptr->pmu.name, -1);
+	if (ret)
+		goto err_free_cpuhp_mem;
+
+	pr_debug("%s performance monitor hardware support registered\n",
+							pmu_ptr->pmu.name);
+
+	return 0;
+
+err_free_cpuhp_mem:
+	imc_common_cpuhp_mem_free(pmu_ptr);
+err_free_mem:
+	imc_common_mem_free(pmu_ptr);
+	return ret;
+}