drivers/cpuidle/lpm-levels-of.c

/* 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) "%s: " fmt, KBUILD_MODNAME

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/err.h>
#include <linux/sysfs.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/moduleparam.h>
#include "lpm-levels.h"

enum lpm_type {
	IDLE = 0,
	SUSPEND,
	LATENCY,
	LPM_TYPE_NR
};

struct lpm_type_str {
	enum lpm_type type;
	char *str;
};

static const struct lpm_type_str lpm_types[] = {
	{IDLE, "idle_enabled"},
	{SUSPEND, "suspend_enabled"},
	{LATENCY, "latency_us"},
};

static DEFINE_PER_CPU(uint32_t *, max_residency);
static DEFINE_PER_CPU(uint32_t *, min_residency);
static struct lpm_level_avail *cpu_level_available[NR_CPUS];
static struct platform_device *lpm_pdev;

static void *get_enabled_ptr(struct kobj_attribute *attr,
					struct lpm_level_avail *avail)
{
	void *arg = NULL;

	if (!strcmp(attr->attr.name, lpm_types[IDLE].str))
		arg = (void *) &avail->idle_enabled;
	else if (!strcmp(attr->attr.name, lpm_types[SUSPEND].str))
		arg = (void *) &avail->suspend_enabled;

	return arg;
}

static struct lpm_level_avail *get_avail_ptr(struct kobject *kobj,
					struct kobj_attribute *attr)
{
	struct lpm_level_avail *avail = NULL;

	if (!strcmp(attr->attr.name, lpm_types[IDLE].str))
		avail = container_of(attr, struct lpm_level_avail,
					idle_enabled_attr);
	else if (!strcmp(attr->attr.name, lpm_types[SUSPEND].str))
		avail = container_of(attr, struct lpm_level_avail,
					suspend_enabled_attr);
	else if (!strcmp(attr->attr.name, lpm_types[LATENCY].str))
		avail = container_of(attr, struct lpm_level_avail,
					latency_attr);

	return avail;
}

static void set_optimum_cpu_residency(struct lpm_cpu *cpu, int cpu_id,
		bool probe_time)
{
	int i, j;
	bool mode_avail;
	uint32_t *maximum_residency = per_cpu(max_residency, cpu_id);
	uint32_t *minimum_residency = per_cpu(min_residency, cpu_id);

	for (i = 0; i < cpu->nlevels; i++) {
		struct power_params *pwr = &cpu->levels[i].pwr;

		mode_avail = probe_time ||
			lpm_cpu_mode_allow(cpu_id, i, true);

		if (!mode_avail) {
			maximum_residency[i] = 0;
			minimum_residency[i] = 0;
			continue;
		}

		maximum_residency[i] = ~0;
		for (j = i + 1; j < cpu->nlevels; j++) {
			mode_avail = probe_time ||
					lpm_cpu_mode_allow(cpu_id, j, true);

			if (mode_avail &&
				(maximum_residency[i] > pwr->residencies[j]) &&
				(pwr->residencies[j] != 0))
				maximum_residency[i] = pwr->residencies[j];
		}

		minimum_residency[i] = pwr->time_overhead_us;
		for (j = i-1; j >= 0; j--) {
			if (probe_time || lpm_cpu_mode_allow(cpu_id, j, true)) {
				minimum_residency[i] = maximum_residency[j] + 1;
				break;
			}
		}
	}
}

static void set_optimum_cluster_residency(struct lpm_cluster *cluster,
		bool probe_time)
{
	int i, j;
	bool mode_avail;

	for (i = 0; i < cluster->nlevels; i++) {
		struct power_params *pwr = &cluster->levels[i].pwr;

		mode_avail = probe_time ||
			lpm_cluster_mode_allow(cluster, i,
					true);

		if (!mode_avail) {
			pwr->max_residency = 0;
			pwr->min_residency = 0;
			continue;
		}

		pwr->max_residency = ~0;
		for (j = i+1; j < cluster->nlevels; j++) {
			mode_avail = probe_time ||
					lpm_cluster_mode_allow(cluster, j,
							true);
			if (mode_avail &&
				(pwr->max_residency > pwr->residencies[j]) &&
				(pwr->residencies[j] != 0))
				pwr->max_residency = pwr->residencies[j];
		}

		pwr->min_residency = pwr->time_overhead_us;
		for (j = i-1;  j >= 0; j--) {
			if (probe_time ||
				lpm_cluster_mode_allow(cluster, j, true)) {
				pwr->min_residency =
				  cluster->levels[j].pwr.max_residency + 1;
				break;
			}
		}
	}
}

uint32_t *get_per_cpu_max_residency(int cpu)
{
	return per_cpu(max_residency, cpu);
}

uint32_t *get_per_cpu_min_residency(int cpu)
{
	return per_cpu(min_residency, cpu);
}

static ssize_t lpm_latency_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	int ret = 0;
	struct kernel_param kp;
	struct lpm_level_avail *avail = get_avail_ptr(kobj, attr);

	if (!avail)
		pr_info("Error\n");

	kp.arg = &avail->latency_us;

	ret = param_get_uint(buf, &kp);
	if (ret > 0) {
		strlcat(buf, "\n", PAGE_SIZE);
		ret++;
	}

	return ret;
}

ssize_t lpm_enable_show(struct kobject *kobj, struct kobj_attribute *attr,
				char *buf)
{
	int ret = 0;
	struct kernel_param kp;

	kp.arg = get_enabled_ptr(attr, get_avail_ptr(kobj, attr));
	ret = param_get_bool(buf, &kp);
	if (ret > 0) {
		strlcat(buf, "\n", PAGE_SIZE);
		ret++;
	}

	return ret;
}

ssize_t lpm_enable_store(struct kobject *kobj, struct kobj_attribute *attr,
				const char *buf, size_t len)
{
	int ret = 0;
	struct kernel_param kp;
	struct lpm_level_avail *avail;

	avail = get_avail_ptr(kobj, attr);
	if (WARN_ON(!avail))
		return -EINVAL;

	kp.arg = get_enabled_ptr(attr, avail);
	ret = param_set_bool(buf, &kp);

	if (avail->cpu_node)
		set_optimum_cpu_residency(avail->data, avail->idx, false);
	else
		set_optimum_cluster_residency(avail->data, false);

	return ret ? ret : len;
}

static int create_lvl_avail_nodes(const char *name,
			struct kobject *parent, struct lpm_level_avail *avail,
			void *data, int index, bool cpu_node)
{
	struct attribute_group *attr_group = NULL;
	struct attribute **attr = NULL;
	struct kobject *kobj = NULL;
	int ret = 0;

	kobj = kobject_create_and_add(name, parent);
	if (!kobj)
		return -ENOMEM;

	attr_group = devm_kzalloc(&lpm_pdev->dev, sizeof(*attr_group),
					GFP_KERNEL);
	if (!attr_group) {
		ret = -ENOMEM;
		goto failed;
	}

	attr = devm_kzalloc(&lpm_pdev->dev,
		sizeof(*attr) * (LPM_TYPE_NR + 1), GFP_KERNEL);
	if (!attr) {
		ret = -ENOMEM;
		goto failed;
	}

	sysfs_attr_init(&avail->idle_enabled_attr.attr);
	avail->idle_enabled_attr.attr.name = lpm_types[IDLE].str;
	avail->idle_enabled_attr.attr.mode = 0644;
	avail->idle_enabled_attr.show = lpm_enable_show;
	avail->idle_enabled_attr.store = lpm_enable_store;

	sysfs_attr_init(&avail->suspend_enabled_attr.attr);
	avail->suspend_enabled_attr.attr.name = lpm_types[SUSPEND].str;
	avail->suspend_enabled_attr.attr.mode = 0644;
	avail->suspend_enabled_attr.show = lpm_enable_show;
	avail->suspend_enabled_attr.store = lpm_enable_store;

	sysfs_attr_init(&avail->latency_attr.attr);
	avail->latency_attr.attr.name = lpm_types[LATENCY].str;
	avail->latency_attr.attr.mode = 0444;
	avail->latency_attr.show = lpm_latency_show;
	avail->latency_attr.store = NULL;

	attr[0] = &avail->idle_enabled_attr.attr;
	attr[1] = &avail->suspend_enabled_attr.attr;
	attr[2] = &avail->latency_attr.attr;
	attr[3] = NULL;
	attr_group->attrs = attr;

	ret = sysfs_create_group(kobj, attr_group);
	if (ret) {
		ret = -ENOMEM;
		goto failed;
	}

	avail->idle_enabled = true;
	avail->suspend_enabled = true;
	avail->kobj = kobj;
	avail->data = data;
	avail->idx = index;
	avail->cpu_node = cpu_node;

	return ret;

failed:
	kobject_put(kobj);
	return ret;
}

static int create_cpu_lvl_nodes(struct lpm_cluster *p, struct kobject *parent)
{
	int cpu;
	int i, cpu_idx;
	struct kobject **cpu_kobj = NULL;
	struct lpm_level_avail *level_list = NULL;
	char cpu_name[20] = {0};
	int ret = 0;
	struct list_head *pos;

	cpu_kobj = devm_kzalloc(&lpm_pdev->dev, sizeof(*cpu_kobj) *
			cpumask_weight(&p->child_cpus), GFP_KERNEL);
	if (!cpu_kobj)
		return -ENOMEM;

	cpu_idx = 0;
	list_for_each(pos, &p->cpu) {
		struct lpm_cpu *lpm_cpu = list_entry(pos, struct lpm_cpu, list);

		for_each_cpu(cpu, &lpm_cpu->related_cpus) {
			snprintf(cpu_name, sizeof(cpu_name), "cpu%d", cpu);
			cpu_kobj[cpu_idx] = kobject_create_and_add(cpu_name,
					parent);
			if (!cpu_kobj[cpu_idx]) {
				ret = -ENOMEM;
				goto release_kobj;
			}

			level_list = devm_kzalloc(&lpm_pdev->dev,
					lpm_cpu->nlevels * sizeof(*level_list),
					GFP_KERNEL);
			if (!level_list) {
				ret = -ENOMEM;
				goto release_kobj;
			}

			/*
			 * Skip enable/disable for WFI. cpuidle expects WFI to
			 * be available at all times.
			 */
			for (i = 1; i < lpm_cpu->nlevels; i++) {
				level_list[i].latency_us =
					p->levels[i].pwr.latency_us;
				ret = create_lvl_avail_nodes(
						lpm_cpu->levels[i].name,
						cpu_kobj[cpu_idx],
						&level_list[i],
						(void *)lpm_cpu, cpu, true);
				if (ret)
					goto release_kobj;
			}

			cpu_level_available[cpu] = level_list;
			cpu_idx++;
		}
	}

	return ret;

release_kobj:
	for (i = 0; i < cpumask_weight(&p->child_cpus); i++)
		kobject_put(cpu_kobj[i]);

	return ret;
}

int create_cluster_lvl_nodes(struct lpm_cluster *p, struct kobject *kobj)
{
	int ret = 0;
	struct lpm_cluster *child = NULL;
	int i;
	struct kobject *cluster_kobj = NULL;

	if (!p)
		return -ENODEV;

	cluster_kobj = kobject_create_and_add(p->cluster_name, kobj);
	if (!cluster_kobj)
		return -ENOMEM;

	for (i = 0; i < p->nlevels; i++) {
		p->levels[i].available.latency_us = p->levels[i].pwr.latency_us;
		ret = create_lvl_avail_nodes(p->levels[i].level_name,
				cluster_kobj, &p->levels[i].available,
				(void *)p, 0, false);
		if (ret)
			return ret;
	}

	list_for_each_entry(child, &p->child, list) {
		ret = create_cluster_lvl_nodes(child, cluster_kobj);
		if (ret)
			return ret;
	}

	if (!list_empty(&p->cpu)) {
		ret = create_cpu_lvl_nodes(p, cluster_kobj);
		if (ret)
			return ret;
	}

	return ret;
}

bool lpm_cpu_mode_allow(unsigned int cpu,
		unsigned int index, bool from_idle)
{
	struct lpm_level_avail *avail = cpu_level_available[cpu];

	if (!lpm_pdev || !avail)
		return !from_idle;

	return !!(from_idle ? avail[index].idle_enabled :
				avail[index].suspend_enabled);
}

bool lpm_cluster_mode_allow(struct lpm_cluster *cluster,
		unsigned int mode, bool from_idle)
{
	struct lpm_level_avail *avail = &cluster->levels[mode].available;

	if (!lpm_pdev || !avail)
		return false;

	return !!(from_idle ? avail->idle_enabled :
				avail->suspend_enabled);
}

static int parse_cluster_params(struct device_node *node,
		struct lpm_cluster *c)
{
	char *key;
	int ret;

	key = "label";
	ret = of_property_read_string(node, key, &c->cluster_name);
	if (ret)
		goto fail;

	key = "qcom,psci-mode-shift";
	ret = of_property_read_u32(node, key, &c->psci_mode_shift);
	if (ret)
		goto fail;

	key = "qcom,psci-mode-mask";
	ret = of_property_read_u32(node, key, &c->psci_mode_mask);
	if (ret)
		goto fail;

	/* Set default_level to 0 as default */
	c->default_level = 0;

	return ret;
fail:
	pr_err("Failed to read key: %s ret: %d\n", key, ret);

	return ret;
}

static int parse_power_params(struct device_node *node,
		struct power_params *pwr)
{
	char *key;
	int ret;

	key = "qcom,latency-us";
	ret  = of_property_read_u32(node, key, &pwr->latency_us);
	if (ret)
		goto fail;

	key = "qcom,ss-power";
	ret = of_property_read_u32(node, key, &pwr->ss_power);
	if (ret)
		goto fail;

	key = "qcom,energy-overhead";
	ret = of_property_read_u32(node, key, &pwr->energy_overhead);
	if (ret)
		goto fail;

	key = "qcom,time-overhead";
	ret = of_property_read_u32(node, key, &pwr->time_overhead_us);
	if (ret)
		goto fail;

	return ret;
fail:
	pr_err("Failed to read key: %s node: %s\n", key, node->name);

	return ret;
}

static int parse_cluster_level(struct device_node *node,
		struct lpm_cluster *cluster)
{
	struct lpm_cluster_level *level = &cluster->levels[cluster->nlevels];
	int ret = -ENOMEM;
	char *key;

	key = "label";
	ret = of_property_read_string(node, key, &level->level_name);
	if (ret)
		goto failed;

	key = "qcom,psci-mode";
	ret = of_property_read_u32(node, key, &level->psci_id);
	if (ret)
		goto failed;

	level->is_reset = of_property_read_bool(node, "qcom,is-reset");

	if (cluster->nlevels != cluster->default_level) {
		key = "qcom,min-child-idx";
		ret = of_property_read_u32(node, key, &level->min_child_level);
		if (ret)
			goto failed;

		if (cluster->min_child_level > level->min_child_level)
			cluster->min_child_level = level->min_child_level;
	}

	level->notify_rpm = of_property_read_bool(node, "qcom,notify-rpm");

	key = "parse_power_params";
	ret = parse_power_params(node, &level->pwr);
	if (ret)
		goto failed;

	key = "qcom,reset-level";
	ret = of_property_read_u32(node, key, &level->reset_level);
	if (ret == -EINVAL)
		level->reset_level = LPM_RESET_LVL_NONE;
	else if (ret)
		goto failed;

	cluster->nlevels++;

	return 0;
failed:
	pr_err("Failed to read key: %s ret: %d\n", key, ret);

	return ret;
}

static int parse_cpu_mode(struct device_node *n, struct lpm_cpu_level *l)
{
	char *key;
	int ret;

	key = "label";
	ret = of_property_read_string(n, key, &l->name);
	if (ret)
		goto fail;

	key = "qcom,psci-cpu-mode";
	ret = of_property_read_u32(n, key, &l->psci_id);
	if (ret)
		goto fail;

	return ret;
fail:
	pr_err("Failed to read key: %s level: %s\n", key, l->name);

	return ret;
}

static int get_cpumask_for_node(struct device_node *node, struct cpumask *mask)
{
	struct device_node *cpu_node;
	int cpu;
	int idx = 0;

	cpu_node = of_parse_phandle(node, "qcom,cpu", idx++);
	if (!cpu_node) {
		pr_info("%s: No CPU phandle, assuming single cluster\n",
				node->full_name);
		/*
		 * Not all targets have the cpu node populated in the device
		 * tree. If cpu node is not populated assume all possible
		 * nodes belong to this cluster
		 */
		cpumask_copy(mask, cpu_possible_mask);
		return 0;
	}

	while (cpu_node) {
		for_each_possible_cpu(cpu) {
			if (of_get_cpu_node(cpu, NULL) == cpu_node) {
				cpumask_set_cpu(cpu, mask);
				break;
			}
		}
		cpu_node = of_parse_phandle(node, "qcom,cpu", idx++);
	}

	return 0;
}

static int calculate_residency(struct power_params *base_pwr,
					struct power_params *next_pwr)
{
	int32_t residency = (int32_t)(next_pwr->energy_overhead -
						base_pwr->energy_overhead) -
		((int32_t)(next_pwr->ss_power * next_pwr->time_overhead_us)
		- (int32_t)(base_pwr->ss_power * base_pwr->time_overhead_us));

	residency /= (int32_t)(base_pwr->ss_power  - next_pwr->ss_power);

	if (residency < 0) {
		pr_err("Residency < 0 for LPM\n");
		return next_pwr->time_overhead_us;
	}

	return residency < next_pwr->time_overhead_us ?
				next_pwr->time_overhead_us : residency;
}

static int parse_cpu(struct device_node *node, struct lpm_cpu *cpu)
{

	struct device_node *n;
	int ret, i, j;
	const char *key;
	for_each_child_of_node(node, n) {
		struct lpm_cpu_level *l = &cpu->levels[cpu->nlevels];

		cpu->nlevels++;

		ret = parse_cpu_mode(n, l);
		if (ret)
			return ret;

		ret = parse_power_params(n, &l->pwr);
		if (ret)
			return ret;

		key = "qcom,use-broadcast-timer";
		l->use_bc_timer = of_property_read_bool(n, key);

		key = "qcom,is-reset";
		l->is_reset = of_property_read_bool(n, key);

		key = "qcom,reset-level";
		ret = of_property_read_u32(n, key, &l->reset_level);
		if (ret == -EINVAL)
			l->reset_level = LPM_RESET_LVL_NONE;
		else if (ret)
			return ret;
	}

	for (i = 0; i < cpu->nlevels; i++) {
		for (j = 0; j < cpu->nlevels; j++) {
			if (i >= j) {
				cpu->levels[i].pwr.residencies[j] = 0;
				continue;
			}

			cpu->levels[i].pwr.residencies[j] =
				calculate_residency(&cpu->levels[i].pwr,
						&cpu->levels[j].pwr);

			pr_info("idx %d %u\n", j,
					cpu->levels[i].pwr.residencies[j]);
		}
	}

	for_each_cpu(i, &cpu->related_cpus) {

		per_cpu(max_residency, i) = devm_kzalloc(&lpm_pdev->dev,
				sizeof(uint32_t) * cpu->nlevels, GFP_KERNEL);
		if (!per_cpu(max_residency, i))
			return -ENOMEM;

		per_cpu(min_residency, i) = devm_kzalloc(&lpm_pdev->dev,
				sizeof(uint32_t) * cpu->nlevels, GFP_KERNEL);
		if (!per_cpu(min_residency, i))
			return -ENOMEM;

		set_optimum_cpu_residency(cpu, i, true);
	}

	return 0;
}

static int parse_cpu_levels(struct device_node *node, struct lpm_cluster *c)
{
	int ret, i;
	char *key;
	struct lpm_cpu *cpu;

	cpu = devm_kzalloc(&lpm_pdev->dev, sizeof(*cpu), GFP_KERNEL);
	if (!cpu)
		return -ENOMEM;

	if (get_cpumask_for_node(node, &cpu->related_cpus))
		return -EINVAL;

	cpu->parent = c;

	key = "qcom,psci-mode-shift";
	ret = of_property_read_u32(node, key, &cpu->psci_mode_shift);
	if (ret)
		goto failed_parse_params;

	key = "qcom,psci-mode-mask";
	ret = of_property_read_u32(node, key, &cpu->psci_mode_mask);
	if (ret)
		goto failed_parse_params;

	key = "parse_cpu";
	ret = parse_cpu(node, cpu);
	if (ret)
		goto failed_parse_cpu;

	cpumask_or(&c->child_cpus, &c->child_cpus, &cpu->related_cpus);
	list_add(&cpu->list, &c->cpu);

	return ret;

failed_parse_cpu:
	for (i = 0; i < cpu->nlevels; i++) {
		kfree(cpu->levels[i].name);
		cpu->levels[i].name = NULL;
	}

failed_parse_params:
	pr_err("Failed to read key: %s node: %s\n", key, node->name);
	return ret;
}

void free_cluster_node(struct lpm_cluster *cluster)
{
	struct list_head *list;
	struct lpm_cpu *cpu, *n;
	int i;

	list_for_each(list, &cluster->child) {
		struct lpm_cluster *n;

		n = list_entry(list, typeof(*n), list);
		list_del(list);
		free_cluster_node(n);
	};

	list_for_each_entry_safe(cpu, n, &cluster->cpu, list) {
		struct lpm_cpu *cpu = list_entry(list, typeof(*cpu), list);

		for (i = 0; i < cpu->nlevels; i++) {
			kfree(cpu->levels[i].name);
			cpu->levels[i].name = NULL;
		}
		list_del(list);
	}
}

/*
 * TODO:
 * Expects a CPU or a cluster only. This ensures that affinity
 * level of a cluster is consistent with reference to its
 * child nodes.
 */
struct lpm_cluster *parse_cluster(struct device_node *node,
		struct lpm_cluster *parent)
{
	struct lpm_cluster *c;
	struct device_node *n;
	char *key;
	int ret = 0;
	int i, j;

	c = devm_kzalloc(&lpm_pdev->dev, sizeof(*c), GFP_KERNEL);
	if (!c)
		return ERR_PTR(-ENOMEM);

	ret = parse_cluster_params(node, c);
	if (ret)
		goto failed_parse_params;

	INIT_LIST_HEAD(&c->child);
	INIT_LIST_HEAD(&c->cpu);
	c->parent = parent;
	spin_lock_init(&c->sync_lock);
	c->min_child_level = NR_LPM_LEVELS;

	for_each_child_of_node(node, n) {

		if (!n->name)
			continue;

		key = "qcom,pm-cluster-level";
		if (!of_node_cmp(n->name, key)) {
			if (parse_cluster_level(n, c))
				goto failed_parse_cluster;
			continue;
		}

		key = "qcom,pm-cluster";
		if (!of_node_cmp(n->name, key)) {
			struct lpm_cluster *child;

			child = parse_cluster(n, c);
			if (!child)
				goto failed_parse_cluster;

			list_add(&child->list, &c->child);
			cpumask_or(&c->child_cpus, &c->child_cpus,
					&child->child_cpus);
			c->aff_level = child->aff_level + 1;
			continue;
		}

		key = "qcom,pm-cpu";
		if (!of_node_cmp(n->name, key)) {
			if (parse_cpu_levels(n, c))
				goto failed_parse_cluster;

			c->aff_level = 1;
		}
	}

	if (cpumask_intersects(&c->child_cpus, cpu_online_mask))
		c->last_level = c->default_level;
	else
		c->last_level = c->nlevels-1;

	for (i = 0; i < c->nlevels; i++) {
		for (j = 0; j < c->nlevels; j++) {
			if (i >= j) {
				c->levels[i].pwr.residencies[j] = 0;
				continue;
			}
			c->levels[i].pwr.residencies[j] = calculate_residency(
				&c->levels[i].pwr, &c->levels[j].pwr);
		}
	}
	set_optimum_cluster_residency(c, true);
	return c;

failed_parse_cluster:
	pr_err("Failed parse cluster:%s\n", key);
	if (parent)
		list_del(&c->list);
	free_cluster_node(c);
failed_parse_params:
	c->parent = NULL;
	pr_err("Failed parse params\n");
	return NULL;
}
struct lpm_cluster *lpm_of_parse_cluster(struct platform_device *pdev)
{
	struct device_node *top = NULL;

	top = of_find_node_by_name(pdev->dev.of_node, "qcom,pm-cluster");
	if (!top) {
		pr_err("Failed to find root node\n");
		return ERR_PTR(-ENODEV);
	}

	lpm_pdev = pdev;
	return parse_cluster(top, NULL);
}

void cluster_dt_walkthrough(struct lpm_cluster *cluster)
{
	struct list_head *list;
	struct lpm_cpu *cpu;
	int i, j;
	static int id;
	char str[10] = {0};

	if (!cluster)
		return;

	for (i = 0; i < id; i++)
		snprintf(str+i, 10 - i, "\t");
	pr_info("%d\n", __LINE__);

	for (i = 0; i < cluster->nlevels; i++) {
		struct lpm_cluster_level *l = &cluster->levels[i];
		pr_info("cluster: %s \t level: %s\n", cluster->cluster_name,
							l->level_name);
	}

	list_for_each_entry(cpu, &cluster->cpu, list) {
		pr_info("%d\n", __LINE__);
		for (j = 0; j < cpu->nlevels; j++)
			pr_info("%s\tCPU level name: %s\n", str,
						cpu->levels[j].name);
	}

	id++;

	list_for_each(list, &cluster->child) {
		struct lpm_cluster *n;

		pr_info("%d\n", __LINE__);
		n = list_entry(list, typeof(*n), list);
		cluster_dt_walkthrough(n);
	}
	id--;
}