drivers/cpufreq/arm_gem5_mc.c - arm/linux-arm-legacy - Git at Google

 /*
  * ARM Multi-Cluster Platforms CPUFreq support for Gem5
  *
  * Copyright (C) 2013 -2014 ARM Ltd.
  *
  * Akash Bagdia <akash.bagdia@arm.com>
  * Vasileios Spiliopoulos <vasileios.spiliopoulos@arm.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  * kind, whether express or implied; 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) KBUILD_MODNAME ": " fmt

 #include <linux/clk.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/cpumask.h>
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/of_platform.h>
 #include <linux/pm_opp.h>
 #include <linux/slab.h>
 #include <linux/topology.h>
 #include <linux/types.h>

 #include "arm_gem5_mc.h"

 static struct cpufreq_arm_mc_ops *arm_mc_ops;
 static struct clk *clk[MAX_CLUSTERS];
 static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
 static atomic_t cluster_usage[MAX_CLUSTERS + 1] = {ATOMIC_INIT(0),
 	ATOMIC_INIT(0)};

 static DEFINE_PER_CPU(unsigned int, physical_cluster);
 static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);

 static struct mutex cluster_lock[MAX_CLUSTERS];

 static unsigned int find_cluster_maxfreq(int cluster)
 {
 	int j;
 	u32 max_freq = 0, cpu_freq;

 	for_each_online_cpu(j) {
 		cpu_freq = per_cpu(cpu_last_req_freq, j);

 		if ((cluster == per_cpu(physical_cluster, j)) &&
 				(max_freq < cpu_freq))
 			max_freq = cpu_freq;
 	}

 	pr_debug("%s: cluster: %d, max freq: %d\n", __func__, cluster,
 			max_freq);

 	return max_freq;
 }

 static unsigned int clk_get_cpu_rate(unsigned int cpu)
 {
 	u32 cur_cluster = per_cpu(physical_cluster, cpu);
 	u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;

 	pr_debug("%s: cpu: %d, cluster: %d, freq: %u\n", __func__, cpu,
 			cur_cluster, rate);

 	return rate;
 }

 static unsigned int mc_cpufreq_get_rate(unsigned int cpu)
 {
 	return clk_get_cpu_rate(cpu);
 }

 static unsigned int
 mc_cpufreq_set_rate(u32 cpu, u32 new_cluster, u32 rate)
 {
 	u32 new_rate;
 	int ret;

 	mutex_lock(&cluster_lock[new_cluster]);

 	new_rate = rate;

 	pr_debug("%s: cpu: %d, new cluster: %d, freq: %d\n",
 			__func__, cpu, new_cluster, new_rate);

 	ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
 	if (WARN_ON(ret)) {
 		pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
 				new_cluster);

 		mutex_unlock(&cluster_lock[new_cluster]);

 		return ret;
 	}

 	mutex_unlock(&cluster_lock[new_cluster]);

 	return 0;
 }

 /* Validate policy frequency range */
 static int mc_cpufreq_verify_policy(struct cpufreq_policy *policy)
 {
 	u32 cur_cluster = cpu_to_cluster(policy->cpu);

 	return cpufreq_frequency_table_verify(policy, freq_table[cur_cluster]);
 }

 /* Set clock frequency */
 static int mc_cpufreq_set_target(struct cpufreq_policy *policy,
 		unsigned int target_freq, unsigned int relation)
 {
 	struct cpufreq_freqs freqs;
 	u32 cpu = policy->cpu, freq_tab_idx, cur_cluster, new_cluster;
 	int ret = 0;

 	cur_cluster = cpu_to_cluster(cpu);
 	new_cluster = per_cpu(physical_cluster, cpu);

 	freqs.old = mc_cpufreq_get_rate(cpu);

 	/* Determine valid target frequency using freq_table */
 	cpufreq_frequency_table_target(policy, freq_table[cur_cluster],
 			target_freq, relation, &freq_tab_idx);
 	freqs.new = freq_table[cur_cluster][freq_tab_idx].frequency;

 	pr_debug("%s: cpu: %d, cluster: %d, oldfreq: %d, target freq: %d, new freq: %d\n",
 			__func__, cpu, cur_cluster, freqs.old, target_freq,
 			freqs.new);

 	if (freqs.old == freqs.new)
 		return 0;

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

 	ret = mc_cpufreq_set_rate(cpu, new_cluster, freqs.new);
 	if (ret)
 		freqs.new = freqs.old;

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

 	return ret;
 }

 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
 {
 	int count;

 	for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
 		;

 	return count;
 }

 /* get the minimum frequency in the cpufreq_frequency_table */
 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
 {
 	int i;
 	uint32_t min_freq = ~0;
 	for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
 		if (table[i].frequency < min_freq)
 			min_freq = table[i].frequency;
 	return min_freq;
 }

 /* get the maximum frequency in the cpufreq_frequency_table */
 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
 {
 	int i;
 	uint32_t max_freq = 0;
 	for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
 		if (table[i].frequency > max_freq)
 			max_freq = table[i].frequency;
 	return max_freq;
 }

 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
 	u32 cluster = cpu_to_cluster(cpu_dev->id);

 	if (!atomic_dec_return(&cluster_usage[cluster])) {
 		clk_put(clk[cluster]);
 		dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 		dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
 	}
 }

 static void put_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
 	u32 cluster = cpu_to_cluster(cpu_dev->id);

 	if (cluster < MAX_CLUSTERS)
 		return _put_cluster_clk_and_freq_table(cpu_dev);
 }

 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
 	u32 cluster = cpu_to_cluster(cpu_dev->id);
 	char name[14] = "cpu-cluster.";
 	int ret;

 	if (atomic_inc_return(&cluster_usage[cluster]) != 1)
 		return 0;

 	ret = arm_mc_ops->init_opp_table(cpu_dev);
 	if (ret) {
 		dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
 				__func__, cpu_dev->id, ret);
 		goto atomic_dec;
 	}

 	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
 	if (ret) {
 		dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
 				__func__, cpu_dev->id, ret);
 		goto atomic_dec;
 	}

 	name[12] = cluster + '0';
 	clk[cluster] = clk_get_sys(name, NULL);
 	if (!IS_ERR(clk[cluster])) {
 		dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
 				__func__, clk[cluster], freq_table[cluster],
 				cluster);
 		return 0;
 	}

 	dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
 			__func__, cpu_dev->id, cluster);
 	ret = PTR_ERR(clk[cluster]);
 	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);

 atomic_dec:
 	atomic_dec(&cluster_usage[cluster]);
 	dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
 			cluster);
 	return ret;
 }

 static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
 	u32 cluster = cpu_to_cluster(cpu_dev->id);

 	if (cluster < MAX_CLUSTERS)
 		return _get_cluster_clk_and_freq_table(cpu_dev);

 	return 0;
 }

 /* Per-CPU initialization */
 static int mc_cpufreq_init(struct cpufreq_policy *policy)
 {
 	u32 cur_cluster = cpu_to_cluster(policy->cpu);
 	struct device *cpu_dev;
 	int ret;

 	cpu_dev = get_cpu_device(policy->cpu);
 	if (!cpu_dev) {
 		pr_err("%s: failed to get cpu%d device\n", __func__,
 				policy->cpu);
 		return -ENODEV;
 	}

 	ret = get_cluster_clk_and_freq_table(cpu_dev);
 	if (ret)
 		return ret;

 	ret = cpufreq_frequency_table_cpuinfo(policy, freq_table[cur_cluster]);
 	if (ret) {
 		dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n",
 				policy->cpu, cur_cluster);
 		put_cluster_clk_and_freq_table(cpu_dev);
 		return ret;
 	}

 	cpufreq_frequency_table_get_attr(freq_table[cur_cluster], policy->cpu);

 	if (cur_cluster < MAX_CLUSTERS) {
 		cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));

 		per_cpu(physical_cluster, policy->cpu) = cur_cluster;
 	} else {
 		pr_err("Invalid current cluster %d\n", cur_cluster);
 		return -ENODEV;
 	}

 	if (arm_mc_ops->get_transition_latency)
 		policy->cpuinfo.transition_latency =
 			arm_mc_ops->get_transition_latency(cpu_dev);
 	else
 		policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

 	policy->cur = clk_get_cpu_rate(policy->cpu);

 	dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
 	return 0;
 }

 /* Export freq_table to sysfs */
 static struct freq_attr *mc_cpufreq_attr[] = {
 	&cpufreq_freq_attr_scaling_available_freqs,
 	NULL,
 };

 static struct cpufreq_driver mc_cpufreq_driver = {
 	.name			= "arm-gem5-mc",
 	.flags			= CPUFREQ_STICKY |
 					CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
 	.verify			= mc_cpufreq_verify_policy,
 	.target			= mc_cpufreq_set_target,
 	.get			= mc_cpufreq_get_rate,
 	.init			= mc_cpufreq_init,
 	.attr			= mc_cpufreq_attr,
 };

 int mc_cpufreq_register(struct cpufreq_arm_mc_ops *ops)
 {
 	int ret, i;

 	if (arm_mc_ops) {
 		pr_debug("%s: Already registered: %s, exiting\n", __func__,
 				arm_mc_ops->name);
 		return -EBUSY;
 	}

 	if (!ops || !strlen(ops->name) || !ops->init_opp_table) {
 		pr_err("%s: Invalid arm_mc_ops, exiting\n", __func__);
 		return -ENODEV;
 	}

 	arm_mc_ops = ops;

 	for (i = 0; i < MAX_CLUSTERS; i++)
 		mutex_init(&cluster_lock[i]);

 	ret = cpufreq_register_driver(&mc_cpufreq_driver);
 	if (ret) {
 		pr_info("%s: Failed registering platform driver: %s, err: %d\n",
 				__func__, ops->name, ret);
 		arm_mc_ops = NULL;
 	} else {
 		pr_info("%s: Registered platform driver: %s\n",
 				__func__, ops->name);
 	}

 	return ret;
 }
 EXPORT_SYMBOL_GPL(mc_cpufreq_register);

 void mc_cpufreq_unregister(struct cpufreq_arm_mc_ops *ops)
 {
 	if (arm_mc_ops != ops) {
 		pr_err("%s: Registered with: %s, can't unregister, exiting\n",
 				__func__, arm_mc_ops->name);
 		return;
 	}

 	cpufreq_unregister_driver(&mc_cpufreq_driver);
 	pr_info("%s: Un-registered platform driver: %s\n", __func__,
 			arm_mc_ops->name);

 	int i;

 	for (i = 0; i < MAX_CLUSTERS; i++) {
 		struct device *cdev = get_cpu_device(i);
 		if (!cdev) {
 			pr_err("%s: failed to get cpu%d device\n",
 					__func__, i);
 			return;
 		}

 		put_cluster_clk_and_freq_table(cdev);
 	}

 	arm_mc_ops = NULL;
 }
 EXPORT_SYMBOL_GPL(mc_cpufreq_unregister);
	/*
	* ARM Multi-Cluster Platforms CPUFreq support for Gem5
	*
	* Copyright (C) 2013 -2014 ARM Ltd.
	*
	* Akash Bagdia <akash.bagdia@arm.com>
	* Vasileios Spiliopoulos <vasileios.spiliopoulos@arm.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* This program is distributed "as is" WITHOUT ANY WARRANTY of any
	* kind, whether express or implied; 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) KBUILD_MODNAME ": " fmt

	#include <linux/clk.h>
	#include <linux/cpu.h>
	#include <linux/cpufreq.h>
	#include <linux/cpumask.h>
	#include <linux/export.h>
	#include <linux/mutex.h>
	#include <linux/of_platform.h>
	#include <linux/pm_opp.h>
	#include <linux/slab.h>
	#include <linux/topology.h>
	#include <linux/types.h>

	#include "arm_gem5_mc.h"

	static struct cpufreq_arm_mc_ops *arm_mc_ops;
	static struct clk *clk[MAX_CLUSTERS];
	static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
	static atomic_t cluster_usage[MAX_CLUSTERS + 1] = {ATOMIC_INIT(0),
	ATOMIC_INIT(0)};

	static DEFINE_PER_CPU(unsigned int, physical_cluster);
	static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);

	static struct mutex cluster_lock[MAX_CLUSTERS];

	static unsigned int find_cluster_maxfreq(int cluster)
	{
	int j;
	u32 max_freq = 0, cpu_freq;

	for_each_online_cpu(j) {
	cpu_freq = per_cpu(cpu_last_req_freq, j);

	if ((cluster == per_cpu(physical_cluster, j)) &&
	(max_freq < cpu_freq))
	max_freq = cpu_freq;
	}

	pr_debug("%s: cluster: %d, max freq: %d\n", __func__, cluster,
	max_freq);

	return max_freq;
	}

	static unsigned int clk_get_cpu_rate(unsigned int cpu)
	{
	u32 cur_cluster = per_cpu(physical_cluster, cpu);
	u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;

	pr_debug("%s: cpu: %d, cluster: %d, freq: %u\n", __func__, cpu,
	cur_cluster, rate);

	return rate;
	}

	static unsigned int mc_cpufreq_get_rate(unsigned int cpu)
	{
	return clk_get_cpu_rate(cpu);
	}

	static unsigned int
	mc_cpufreq_set_rate(u32 cpu, u32 new_cluster, u32 rate)
	{
	u32 new_rate;
	int ret;

	mutex_lock(&cluster_lock[new_cluster]);

	new_rate = rate;

	pr_debug("%s: cpu: %d, new cluster: %d, freq: %d\n",
	__func__, cpu, new_cluster, new_rate);

	ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
	if (WARN_ON(ret)) {
	pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
	new_cluster);

	mutex_unlock(&cluster_lock[new_cluster]);

	return ret;
	}

	mutex_unlock(&cluster_lock[new_cluster]);

	return 0;
	}

	/* Validate policy frequency range */
	static int mc_cpufreq_verify_policy(struct cpufreq_policy *policy)
	{
	u32 cur_cluster = cpu_to_cluster(policy->cpu);

	return cpufreq_frequency_table_verify(policy, freq_table[cur_cluster]);
	}

	/* Set clock frequency */
	static int mc_cpufreq_set_target(struct cpufreq_policy *policy,
	unsigned int target_freq, unsigned int relation)
	{
	struct cpufreq_freqs freqs;
	u32 cpu = policy->cpu, freq_tab_idx, cur_cluster, new_cluster;
	int ret = 0;

	cur_cluster = cpu_to_cluster(cpu);
	new_cluster = per_cpu(physical_cluster, cpu);

	freqs.old = mc_cpufreq_get_rate(cpu);

	/* Determine valid target frequency using freq_table */
	cpufreq_frequency_table_target(policy, freq_table[cur_cluster],
	target_freq, relation, &freq_tab_idx);
	freqs.new = freq_table[cur_cluster][freq_tab_idx].frequency;

	pr_debug("%s: cpu: %d, cluster: %d, oldfreq: %d, target freq: %d, new freq: %d\n",
	__func__, cpu, cur_cluster, freqs.old, target_freq,
	freqs.new);

	if (freqs.old == freqs.new)
	return 0;

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

	ret = mc_cpufreq_set_rate(cpu, new_cluster, freqs.new);
	if (ret)
	freqs.new = freqs.old;

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

	return ret;
	}

	static inline u32 get_table_count(struct cpufreq_frequency_table *table)
	{
	int count;

	for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
	;

	return count;
	}

	/* get the minimum frequency in the cpufreq_frequency_table */
	static inline u32 get_table_min(struct cpufreq_frequency_table *table)
	{
	int i;
	uint32_t min_freq = ~0;
	for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
	if (table[i].frequency < min_freq)
	min_freq = table[i].frequency;
	return min_freq;
	}

	/* get the maximum frequency in the cpufreq_frequency_table */
	static inline u32 get_table_max(struct cpufreq_frequency_table *table)
	{
	int i;
	uint32_t max_freq = 0;
	for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
	if (table[i].frequency > max_freq)
	max_freq = table[i].frequency;
	return max_freq;
	}

	static void _put_cluster_clk_and_freq_table(struct device *cpu_dev)
	{
	u32 cluster = cpu_to_cluster(cpu_dev->id);

	if (!atomic_dec_return(&cluster_usage[cluster])) {
	clk_put(clk[cluster]);
	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
	dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
	}
	}

	static void put_cluster_clk_and_freq_table(struct device *cpu_dev)
	{
	u32 cluster = cpu_to_cluster(cpu_dev->id);

	if (cluster < MAX_CLUSTERS)
	return _put_cluster_clk_and_freq_table(cpu_dev);
	}

	static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
	{
	u32 cluster = cpu_to_cluster(cpu_dev->id);
	char name[14] = "cpu-cluster.";
	int ret;

	if (atomic_inc_return(&cluster_usage[cluster]) != 1)
	return 0;

	ret = arm_mc_ops->init_opp_table(cpu_dev);
	if (ret) {
	dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
	__func__, cpu_dev->id, ret);
	goto atomic_dec;
	}

	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
	if (ret) {
	dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
	__func__, cpu_dev->id, ret);
	goto atomic_dec;
	}

	name[12] = cluster + '0';
	clk[cluster] = clk_get_sys(name, NULL);
	if (!IS_ERR(clk[cluster])) {
	dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
	__func__, clk[cluster], freq_table[cluster],
	cluster);
	return 0;
	}

	dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
	__func__, cpu_dev->id, cluster);
	ret = PTR_ERR(clk[cluster]);
	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);

	atomic_dec:
	atomic_dec(&cluster_usage[cluster]);
	dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
	cluster);
	return ret;
	}

	static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
	{
	u32 cluster = cpu_to_cluster(cpu_dev->id);

	if (cluster < MAX_CLUSTERS)
	return _get_cluster_clk_and_freq_table(cpu_dev);

	return 0;
	}

	/* Per-CPU initialization */
	static int mc_cpufreq_init(struct cpufreq_policy *policy)
	{
	u32 cur_cluster = cpu_to_cluster(policy->cpu);
	struct device *cpu_dev;
	int ret;

	cpu_dev = get_cpu_device(policy->cpu);
	if (!cpu_dev) {
	pr_err("%s: failed to get cpu%d device\n", __func__,
	policy->cpu);
	return -ENODEV;
	}

	ret = get_cluster_clk_and_freq_table(cpu_dev);
	if (ret)
	return ret;

	ret = cpufreq_frequency_table_cpuinfo(policy, freq_table[cur_cluster]);
	if (ret) {
	dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n",
	policy->cpu, cur_cluster);
	put_cluster_clk_and_freq_table(cpu_dev);
	return ret;
	}

	cpufreq_frequency_table_get_attr(freq_table[cur_cluster], policy->cpu);

	if (cur_cluster < MAX_CLUSTERS) {
	cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));

	per_cpu(physical_cluster, policy->cpu) = cur_cluster;
	} else {
	pr_err("Invalid current cluster %d\n", cur_cluster);
	return -ENODEV;
	}

	if (arm_mc_ops->get_transition_latency)
	policy->cpuinfo.transition_latency =
	arm_mc_ops->get_transition_latency(cpu_dev);
	else
	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

	policy->cur = clk_get_cpu_rate(policy->cpu);

	dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
	return 0;
	}

	/* Export freq_table to sysfs */
	static struct freq_attr *mc_cpufreq_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	NULL,
	};

	static struct cpufreq_driver mc_cpufreq_driver = {
	.name = "arm-gem5-mc",
	.flags = CPUFREQ_STICKY \|
	CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
	.verify = mc_cpufreq_verify_policy,
	.target = mc_cpufreq_set_target,
	.get = mc_cpufreq_get_rate,
	.init = mc_cpufreq_init,
	.attr = mc_cpufreq_attr,
	};

	int mc_cpufreq_register(struct cpufreq_arm_mc_ops *ops)
	{
	int ret, i;

	if (arm_mc_ops) {
	pr_debug("%s: Already registered: %s, exiting\n", __func__,
	arm_mc_ops->name);
	return -EBUSY;
	}

	if (!ops \|\| !strlen(ops->name) \|\| !ops->init_opp_table) {
	pr_err("%s: Invalid arm_mc_ops, exiting\n", __func__);
	return -ENODEV;
	}

	arm_mc_ops = ops;

	for (i = 0; i < MAX_CLUSTERS; i++)
	mutex_init(&cluster_lock[i]);

	ret = cpufreq_register_driver(&mc_cpufreq_driver);
	if (ret) {
	pr_info("%s: Failed registering platform driver: %s, err: %d\n",
	__func__, ops->name, ret);
	arm_mc_ops = NULL;
	} else {
	pr_info("%s: Registered platform driver: %s\n",
	__func__, ops->name);
	}

	return ret;
	}
	EXPORT_SYMBOL_GPL(mc_cpufreq_register);

	void mc_cpufreq_unregister(struct cpufreq_arm_mc_ops *ops)
	{
	if (arm_mc_ops != ops) {
	pr_err("%s: Registered with: %s, can't unregister, exiting\n",
	__func__, arm_mc_ops->name);
	return;
	}

	cpufreq_unregister_driver(&mc_cpufreq_driver);
	pr_info("%s: Un-registered platform driver: %s\n", __func__,
	arm_mc_ops->name);

	int i;

	for (i = 0; i < MAX_CLUSTERS; i++) {
	struct device *cdev = get_cpu_device(i);
	if (!cdev) {
	pr_err("%s: failed to get cpu%d device\n",
	__func__, i);
	return;
	}

	put_cluster_clk_and_freq_table(cdev);
	}

	arm_mc_ops = NULL;
	}
	EXPORT_SYMBOL_GPL(mc_cpufreq_unregister);