drivers/devfreq/arm-memlat-mon.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
  * only version 2 as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */

 #define pr_fmt(fmt) "arm-memlat-mon: " fmt

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/slab.h>
 #include <linux/irq.h>
 #include <linux/cpu_pm.h>
 #include <linux/cpu.h>
 #include "governor.h"
 #include "governor_memlat.h"
 #include <linux/perf_event.h>

 enum ev_index {
 	INST_IDX,
 	CM_IDX,
 	CYC_IDX,
 	NUM_EVENTS
 };
 #define INST_EV		0x08
 #define L2DM_EV		0x17
 #define CYC_EV		0x11

 struct event_data {
 	struct perf_event *pevent;
 	unsigned long prev_count;
 };

 struct cpu_pmu_stats {
 	struct event_data events[NUM_EVENTS];
 	ktime_t prev_ts;
 };

 struct cpu_grp_info {
 	cpumask_t cpus;
 	cpumask_t inited_cpus;
 	unsigned long cache_miss_event;
 	unsigned long inst_event;
 	struct cpu_pmu_stats *cpustats;
 	struct memlat_hwmon hw;
 	struct notifier_block arm_memlat_cpu_notif;
 	struct list_head mon_list;
 };

 #define to_cpustats(cpu_grp, cpu) \
 	(&cpu_grp->cpustats[cpu - cpumask_first(&cpu_grp->cpus)])
 #define to_devstats(cpu_grp, cpu) \
 	(&cpu_grp->hw.core_stats[cpu - cpumask_first(&cpu_grp->cpus)])
 #define to_cpu_grp(hwmon) container_of(hwmon, struct cpu_grp_info, hw)

 static LIST_HEAD(memlat_mon_list);
 static DEFINE_MUTEX(list_lock);

 static unsigned long compute_freq(struct cpu_pmu_stats *cpustats,
 						unsigned long cyc_cnt)
 {
 	ktime_t ts;
 	unsigned int diff;
 	unsigned long freq = 0;

 	ts = ktime_get();
 	diff = ktime_to_us(ktime_sub(ts, cpustats->prev_ts));
 	if (!diff)
 		diff = 1;
 	cpustats->prev_ts = ts;
 	freq = cyc_cnt;
 	do_div(freq, diff);

 	return freq;
 }

 #define MAX_COUNT_LIM 0xFFFFFFFFFFFFFFFF
 static inline unsigned long read_event(struct event_data *event)
 {
 	unsigned long ev_count;
 	u64 total, enabled, running;

 	total = perf_event_read_value(event->pevent, &enabled, &running);
 	if (total >= event->prev_count)
 		ev_count = total - event->prev_count;
 	else
 		ev_count = (MAX_COUNT_LIM - event->prev_count) + total;

 	event->prev_count = total;

 	return ev_count;
 }

 static void read_perf_counters(int cpu, struct cpu_grp_info *cpu_grp)
 {
 	struct cpu_pmu_stats *cpustats = to_cpustats(cpu_grp, cpu);
 	struct dev_stats *devstats = to_devstats(cpu_grp, cpu);
 	unsigned long cyc_cnt;

 	devstats->inst_count = read_event(&cpustats->events[INST_IDX]);
 	devstats->mem_count = read_event(&cpustats->events[CM_IDX]);
 	cyc_cnt = read_event(&cpustats->events[CYC_IDX]);
 	devstats->freq = compute_freq(cpustats, cyc_cnt);
 }

 static unsigned long get_cnt(struct memlat_hwmon *hw)
 {
 	int cpu;
 	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);

 	for_each_cpu(cpu, &cpu_grp->inited_cpus)
 		read_perf_counters(cpu, cpu_grp);

 	return 0;
 }

 static void delete_events(struct cpu_pmu_stats *cpustats)
 {
 	int i;

 	for (i = 0; i < NUM_EVENTS; i++) {
 		cpustats->events[i].prev_count = 0;
 		perf_event_release_kernel(cpustats->events[i].pevent);
 	}
 }

 static void stop_hwmon(struct memlat_hwmon *hw)
 {
 	int cpu;
 	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);
 	struct dev_stats *devstats;

 	get_online_cpus();
 	for_each_cpu(cpu, &cpu_grp->inited_cpus) {
 		delete_events(to_cpustats(cpu_grp, cpu));

 		/* Clear governor data */
 		devstats = to_devstats(cpu_grp, cpu);
 		devstats->inst_count = 0;
 		devstats->mem_count = 0;
 		devstats->freq = 0;
 	}
 	mutex_lock(&list_lock);
 	if (!cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
 		list_del(&cpu_grp->mon_list);
 	mutex_unlock(&list_lock);
 	cpumask_clear(&cpu_grp->inited_cpus);

 	put_online_cpus();

 	unregister_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);
 }

 static struct perf_event_attr *alloc_attr(void)
 {
 	struct perf_event_attr *attr;

 	attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
 	if (!attr)
 		return attr;

 	attr->type = PERF_TYPE_RAW;
 	attr->size = sizeof(struct perf_event_attr);
 	attr->pinned = 1;
 	attr->exclude_idle = 1;

 	return attr;
 }

 static int set_events(struct cpu_grp_info *cpu_grp, int cpu)
 {
 	struct perf_event *pevent;
 	struct perf_event_attr *attr;
 	int err;
 	struct cpu_pmu_stats *cpustats = to_cpustats(cpu_grp, cpu);

 	/* Allocate an attribute for event initialization */
 	attr = alloc_attr();
 	if (!attr)
 		return -ENOMEM;

 	attr->config = cpu_grp->inst_event;
 	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
 	if (IS_ERR(pevent))
 		goto err_out;
 	cpustats->events[INST_IDX].pevent = pevent;
 	perf_event_enable(cpustats->events[INST_IDX].pevent);

 	attr->config = cpu_grp->cache_miss_event;
 	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
 	if (IS_ERR(pevent))
 		goto err_out;
 	cpustats->events[CM_IDX].pevent = pevent;
 	perf_event_enable(cpustats->events[CM_IDX].pevent);

 	attr->config = CYC_EV;
 	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
 	if (IS_ERR(pevent))
 		goto err_out;
 	cpustats->events[CYC_IDX].pevent = pevent;
 	perf_event_enable(cpustats->events[CYC_IDX].pevent);

 	kfree(attr);
 	return 0;

 err_out:
 	err = PTR_ERR(pevent);
 	kfree(attr);
 	return err;
 }

 static int arm_memlat_cpu_callback(struct notifier_block *nb,
 		unsigned long action, void *hcpu)
 {
 	unsigned long cpu = (unsigned long)hcpu;
 	struct cpu_grp_info *cpu_grp, *tmp;

 	if (action != CPU_ONLINE)
 		return NOTIFY_OK;

 	mutex_lock(&list_lock);
 	list_for_each_entry_safe(cpu_grp, tmp, &memlat_mon_list, mon_list) {
 		if (!cpumask_test_cpu(cpu, &cpu_grp->cpus) ||
 		    cpumask_test_cpu(cpu, &cpu_grp->inited_cpus))
 			continue;
 		if (set_events(cpu_grp, cpu))
 			pr_warn("Failed to create perf ev for CPU%lu\n", cpu);
 		else
 			cpumask_set_cpu(cpu, &cpu_grp->inited_cpus);
 		if (cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
 			list_del(&cpu_grp->mon_list);
 	}
 	mutex_unlock(&list_lock);

 	return NOTIFY_OK;
 }

 static int start_hwmon(struct memlat_hwmon *hw)
 {
 	int cpu, ret = 0;
 	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);

 	register_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);

 	get_online_cpus();
 	for_each_cpu(cpu, &cpu_grp->cpus) {
 		ret = set_events(cpu_grp, cpu);
 		if (ret) {
 			if (!cpu_online(cpu)) {
 				ret = 0;
 			} else {
 				pr_warn("Perf event init failed on CPU%d\n",
 					cpu);
 				break;
 			}
 		} else {
 			cpumask_set_cpu(cpu, &cpu_grp->inited_cpus);
 		}
 	}
 	mutex_lock(&list_lock);
 	if (!cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
 		list_add_tail(&cpu_grp->mon_list, &memlat_mon_list);
 	mutex_unlock(&list_lock);

 	put_online_cpus();

 	return ret;
 }

 static int get_mask_from_dev_handle(struct platform_device *pdev,
 					cpumask_t *mask)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *dev_phandle;
 	struct device *cpu_dev;
 	int cpu, i = 0;
 	int ret = -ENOENT;

 	dev_phandle = of_parse_phandle(dev->of_node, "qcom,cpulist", i++);
 	while (dev_phandle) {
 		for_each_possible_cpu(cpu) {
 			cpu_dev = get_cpu_device(cpu);
 			if (cpu_dev && cpu_dev->of_node == dev_phandle) {
 				cpumask_set_cpu(cpu, mask);
 				ret = 0;
 				break;
 			}
 		}
 		dev_phandle = of_parse_phandle(dev->of_node,
 						"qcom,cpulist", i++);
 	}

 	return ret;
 }

 static int arm_memlat_mon_driver_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct memlat_hwmon *hw;
 	struct cpu_grp_info *cpu_grp;
 	int cpu, ret;
 	u32 cachemiss_ev, inst_ev;

 	cpu_grp = devm_kzalloc(dev, sizeof(*cpu_grp), GFP_KERNEL);
 	if (!cpu_grp)
 		return -ENOMEM;
 	cpu_grp->arm_memlat_cpu_notif.notifier_call = arm_memlat_cpu_callback;
 	hw = &cpu_grp->hw;

 	hw->dev = dev;
 	hw->of_node = of_parse_phandle(dev->of_node, "qcom,target-dev", 0);
 	if (!hw->of_node) {
 		dev_err(dev, "Couldn't find a target device\n");
 		return -ENODEV;
 	}

 	if (get_mask_from_dev_handle(pdev, &cpu_grp->cpus)) {
 		dev_err(dev, "CPU list is empty\n");
 		return -ENODEV;
 	}

 	hw->num_cores = cpumask_weight(&cpu_grp->cpus);
 	hw->core_stats = devm_kzalloc(dev, hw->num_cores *
 				sizeof(*(hw->core_stats)), GFP_KERNEL);
 	if (!hw->core_stats)
 		return -ENOMEM;

 	cpu_grp->cpustats = devm_kzalloc(dev, hw->num_cores *
 			sizeof(*(cpu_grp->cpustats)), GFP_KERNEL);
 	if (!cpu_grp->cpustats)
 		return -ENOMEM;

 	ret = of_property_read_u32(dev->of_node, "qcom,cachemiss-ev",
 			&cachemiss_ev);
 	if (ret) {
 		dev_dbg(dev, "Cache Miss event not specified. Using def:0x%x\n",
 				L2DM_EV);
 		cachemiss_ev = L2DM_EV;
 	}
 	cpu_grp->cache_miss_event = cachemiss_ev;

 	ret = of_property_read_u32(dev->of_node, "qcom,inst-ev", &inst_ev);
 	if (ret) {
 		dev_dbg(dev, "Inst event not specified. Using def:0x%x\n",
 				INST_EV);
 		inst_ev = INST_EV;
 	}
 	cpu_grp->inst_event = inst_ev;

 	for_each_cpu(cpu, &cpu_grp->cpus)
 		to_devstats(cpu_grp, cpu)->id = cpu;

 	hw->start_hwmon = &start_hwmon;
 	hw->stop_hwmon = &stop_hwmon;
 	hw->get_cnt = &get_cnt;

 	ret = register_memlat(dev, hw);
 	if (ret) {
 		pr_err("Mem Latency Gov registration failed\n");
 		return ret;
 	}

 	return 0;
 }

 static const struct of_device_id memlat_match_table[] = {
 	{ .compatible = "qcom,arm-memlat-mon" },
 	{}
 };

 static struct platform_driver arm_memlat_mon_driver = {
 	.probe = arm_memlat_mon_driver_probe,
 	.driver = {
 		.name = "arm-memlat-mon",
 		.of_match_table = memlat_match_table,
 	},
 };

 module_platform_driver(arm_memlat_mon_driver);
	/*
	* Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 and
	* only version 2 as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/

	#define pr_fmt(fmt) "arm-memlat-mon: " fmt

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/of.h>
	#include <linux/of_irq.h>
	#include <linux/slab.h>
	#include <linux/irq.h>
	#include <linux/cpu_pm.h>
	#include <linux/cpu.h>
	#include "governor.h"
	#include "governor_memlat.h"
	#include <linux/perf_event.h>

	enum ev_index {
	INST_IDX,
	CM_IDX,
	CYC_IDX,
	NUM_EVENTS
	};
	#define INST_EV 0x08
	#define L2DM_EV 0x17
	#define CYC_EV 0x11

	struct event_data {
	struct perf_event *pevent;
	unsigned long prev_count;
	};

	struct cpu_pmu_stats {
	struct event_data events[NUM_EVENTS];
	ktime_t prev_ts;
	};

	struct cpu_grp_info {
	cpumask_t cpus;
	cpumask_t inited_cpus;
	unsigned long cache_miss_event;
	unsigned long inst_event;
	struct cpu_pmu_stats *cpustats;
	struct memlat_hwmon hw;
	struct notifier_block arm_memlat_cpu_notif;
	struct list_head mon_list;
	};

	#define to_cpustats(cpu_grp, cpu) \
	(&cpu_grp->cpustats[cpu - cpumask_first(&cpu_grp->cpus)])
	#define to_devstats(cpu_grp, cpu) \
	(&cpu_grp->hw.core_stats[cpu - cpumask_first(&cpu_grp->cpus)])
	#define to_cpu_grp(hwmon) container_of(hwmon, struct cpu_grp_info, hw)

	static LIST_HEAD(memlat_mon_list);
	static DEFINE_MUTEX(list_lock);

	static unsigned long compute_freq(struct cpu_pmu_stats *cpustats,
	unsigned long cyc_cnt)
	{
	ktime_t ts;
	unsigned int diff;
	unsigned long freq = 0;

	ts = ktime_get();
	diff = ktime_to_us(ktime_sub(ts, cpustats->prev_ts));
	if (!diff)
	diff = 1;
	cpustats->prev_ts = ts;
	freq = cyc_cnt;
	do_div(freq, diff);

	return freq;
	}

	#define MAX_COUNT_LIM 0xFFFFFFFFFFFFFFFF
	static inline unsigned long read_event(struct event_data *event)
	{
	unsigned long ev_count;
	u64 total, enabled, running;

	total = perf_event_read_value(event->pevent, &enabled, &running);
	if (total >= event->prev_count)
	ev_count = total - event->prev_count;
	else
	ev_count = (MAX_COUNT_LIM - event->prev_count) + total;

	event->prev_count = total;

	return ev_count;
	}

	static void read_perf_counters(int cpu, struct cpu_grp_info *cpu_grp)
	{
	struct cpu_pmu_stats *cpustats = to_cpustats(cpu_grp, cpu);
	struct dev_stats *devstats = to_devstats(cpu_grp, cpu);
	unsigned long cyc_cnt;

	devstats->inst_count = read_event(&cpustats->events[INST_IDX]);
	devstats->mem_count = read_event(&cpustats->events[CM_IDX]);
	cyc_cnt = read_event(&cpustats->events[CYC_IDX]);
	devstats->freq = compute_freq(cpustats, cyc_cnt);
	}

	static unsigned long get_cnt(struct memlat_hwmon *hw)
	{
	int cpu;
	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);

	for_each_cpu(cpu, &cpu_grp->inited_cpus)
	read_perf_counters(cpu, cpu_grp);

	return 0;
	}

	static void delete_events(struct cpu_pmu_stats *cpustats)
	{
	int i;

	for (i = 0; i < NUM_EVENTS; i++) {
	cpustats->events[i].prev_count = 0;
	perf_event_release_kernel(cpustats->events[i].pevent);
	}
	}

	static void stop_hwmon(struct memlat_hwmon *hw)
	{
	int cpu;
	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);
	struct dev_stats *devstats;

	get_online_cpus();
	for_each_cpu(cpu, &cpu_grp->inited_cpus) {
	delete_events(to_cpustats(cpu_grp, cpu));

	/* Clear governor data */
	devstats = to_devstats(cpu_grp, cpu);
	devstats->inst_count = 0;
	devstats->mem_count = 0;
	devstats->freq = 0;
	}
	mutex_lock(&list_lock);
	if (!cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
	list_del(&cpu_grp->mon_list);
	mutex_unlock(&list_lock);
	cpumask_clear(&cpu_grp->inited_cpus);

	put_online_cpus();

	unregister_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);
	}

	static struct perf_event_attr *alloc_attr(void)
	{
	struct perf_event_attr *attr;

	attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
	if (!attr)
	return attr;

	attr->type = PERF_TYPE_RAW;
	attr->size = sizeof(struct perf_event_attr);
	attr->pinned = 1;
	attr->exclude_idle = 1;

	return attr;
	}

	static int set_events(struct cpu_grp_info *cpu_grp, int cpu)
	{
	struct perf_event *pevent;
	struct perf_event_attr *attr;
	int err;
	struct cpu_pmu_stats *cpustats = to_cpustats(cpu_grp, cpu);

	/* Allocate an attribute for event initialization */
	attr = alloc_attr();
	if (!attr)
	return -ENOMEM;

	attr->config = cpu_grp->inst_event;
	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
	if (IS_ERR(pevent))
	goto err_out;
	cpustats->events[INST_IDX].pevent = pevent;
	perf_event_enable(cpustats->events[INST_IDX].pevent);

	attr->config = cpu_grp->cache_miss_event;
	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
	if (IS_ERR(pevent))
	goto err_out;
	cpustats->events[CM_IDX].pevent = pevent;
	perf_event_enable(cpustats->events[CM_IDX].pevent);

	attr->config = CYC_EV;
	pevent = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
	if (IS_ERR(pevent))
	goto err_out;
	cpustats->events[CYC_IDX].pevent = pevent;
	perf_event_enable(cpustats->events[CYC_IDX].pevent);

	kfree(attr);
	return 0;

	err_out:
	err = PTR_ERR(pevent);
	kfree(attr);
	return err;
	}

	static int arm_memlat_cpu_callback(struct notifier_block *nb,
	unsigned long action, void *hcpu)
	{
	unsigned long cpu = (unsigned long)hcpu;
	struct cpu_grp_info cpu_grp, tmp;

	if (action != CPU_ONLINE)
	return NOTIFY_OK;

	mutex_lock(&list_lock);
	list_for_each_entry_safe(cpu_grp, tmp, &memlat_mon_list, mon_list) {
	if (!cpumask_test_cpu(cpu, &cpu_grp->cpus) \|\|
	cpumask_test_cpu(cpu, &cpu_grp->inited_cpus))
	continue;
	if (set_events(cpu_grp, cpu))
	pr_warn("Failed to create perf ev for CPU%lu\n", cpu);
	else
	cpumask_set_cpu(cpu, &cpu_grp->inited_cpus);
	if (cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
	list_del(&cpu_grp->mon_list);
	}
	mutex_unlock(&list_lock);

	return NOTIFY_OK;
	}

	static int start_hwmon(struct memlat_hwmon *hw)
	{
	int cpu, ret = 0;
	struct cpu_grp_info *cpu_grp = to_cpu_grp(hw);

	register_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);

	get_online_cpus();
	for_each_cpu(cpu, &cpu_grp->cpus) {
	ret = set_events(cpu_grp, cpu);
	if (ret) {
	if (!cpu_online(cpu)) {
	ret = 0;
	} else {
	pr_warn("Perf event init failed on CPU%d\n",
	cpu);
	break;
	}
	} else {
	cpumask_set_cpu(cpu, &cpu_grp->inited_cpus);
	}
	}
	mutex_lock(&list_lock);
	if (!cpumask_equal(&cpu_grp->cpus, &cpu_grp->inited_cpus))
	list_add_tail(&cpu_grp->mon_list, &memlat_mon_list);
	mutex_unlock(&list_lock);

	put_online_cpus();

	return ret;
	}

	static int get_mask_from_dev_handle(struct platform_device *pdev,
	cpumask_t *mask)
	{
	struct device *dev = &pdev->dev;
	struct device_node *dev_phandle;
	struct device *cpu_dev;
	int cpu, i = 0;
	int ret = -ENOENT;

	dev_phandle = of_parse_phandle(dev->of_node, "qcom,cpulist", i++);
	while (dev_phandle) {
	for_each_possible_cpu(cpu) {
	cpu_dev = get_cpu_device(cpu);
	if (cpu_dev && cpu_dev->of_node == dev_phandle) {
	cpumask_set_cpu(cpu, mask);
	ret = 0;
	break;
	}
	}
	dev_phandle = of_parse_phandle(dev->of_node,
	"qcom,cpulist", i++);
	}

	return ret;
	}

	static int arm_memlat_mon_driver_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct memlat_hwmon *hw;
	struct cpu_grp_info *cpu_grp;
	int cpu, ret;
	u32 cachemiss_ev, inst_ev;

	cpu_grp = devm_kzalloc(dev, sizeof(*cpu_grp), GFP_KERNEL);
	if (!cpu_grp)
	return -ENOMEM;
	cpu_grp->arm_memlat_cpu_notif.notifier_call = arm_memlat_cpu_callback;
	hw = &cpu_grp->hw;

	hw->dev = dev;
	hw->of_node = of_parse_phandle(dev->of_node, "qcom,target-dev", 0);
	if (!hw->of_node) {
	dev_err(dev, "Couldn't find a target device\n");
	return -ENODEV;
	}

	if (get_mask_from_dev_handle(pdev, &cpu_grp->cpus)) {
	dev_err(dev, "CPU list is empty\n");
	return -ENODEV;
	}

	hw->num_cores = cpumask_weight(&cpu_grp->cpus);
	hw->core_stats = devm_kzalloc(dev, hw->num_cores *
	sizeof(*(hw->core_stats)), GFP_KERNEL);
	if (!hw->core_stats)
	return -ENOMEM;

	cpu_grp->cpustats = devm_kzalloc(dev, hw->num_cores *
	sizeof(*(cpu_grp->cpustats)), GFP_KERNEL);
	if (!cpu_grp->cpustats)
	return -ENOMEM;

	ret = of_property_read_u32(dev->of_node, "qcom,cachemiss-ev",
	&cachemiss_ev);
	if (ret) {
	dev_dbg(dev, "Cache Miss event not specified. Using def:0x%x\n",
	L2DM_EV);
	cachemiss_ev = L2DM_EV;
	}
	cpu_grp->cache_miss_event = cachemiss_ev;

	ret = of_property_read_u32(dev->of_node, "qcom,inst-ev", &inst_ev);
	if (ret) {
	dev_dbg(dev, "Inst event not specified. Using def:0x%x\n",
	INST_EV);
	inst_ev = INST_EV;
	}
	cpu_grp->inst_event = inst_ev;

	for_each_cpu(cpu, &cpu_grp->cpus)
	to_devstats(cpu_grp, cpu)->id = cpu;

	hw->start_hwmon = &start_hwmon;
	hw->stop_hwmon = &stop_hwmon;
	hw->get_cnt = &get_cnt;

	ret = register_memlat(dev, hw);
	if (ret) {
	pr_err("Mem Latency Gov registration failed\n");
	return ret;
	}

	return 0;
	}

	static const struct of_device_id memlat_match_table[] = {
	{ .compatible = "qcom,arm-memlat-mon" },
	{}
	};

	static struct platform_driver arm_memlat_mon_driver = {
	.probe = arm_memlat_mon_driver_probe,
	.driver = {
	.name = "arm-memlat-mon",
	.of_match_table = memlat_match_table,
	},
	};

	module_platform_driver(arm_memlat_mon_driver);