drivers/cpufreq/powernv-cpufreq.c - kernel/msm-4.9 - Gitiles

 /*
  * POWERNV cpufreq driver for the IBM POWER processors
  *
  * (C) Copyright IBM 2014
  *
  * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
  * 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)	"powernv-cpufreq: " fmt

 #include <linux/kernel.h>
 #include <linux/sysfs.h>
 #include <linux/cpumask.h>
 #include <linux/module.h>
 #include <linux/cpufreq.h>
 #include <linux/smp.h>
 #include <linux/of.h>
 #include <linux/reboot.h>

 #include <asm/cputhreads.h>
 #include <asm/firmware.h>
 #include <asm/reg.h>
 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */

 #define POWERNV_MAX_PSTATES	256

 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
 static bool rebooting;

 /*
  * Note: The set of pstates consists of contiguous integers, the
  * smallest of which is indicated by powernv_pstate_info.min, the
  * largest of which is indicated by powernv_pstate_info.max.
  *
  * The nominal pstate is the highest non-turbo pstate in this
  * platform. This is indicated by powernv_pstate_info.nominal.
  */
 static struct powernv_pstate_info {
 	int min;
 	int max;
 	int nominal;
 	int nr_pstates;
 } powernv_pstate_info;

 /*
  * Initialize the freq table based on data obtained
  * from the firmware passed via device-tree
  */
 static int init_powernv_pstates(void)
 {
 	struct device_node *power_mgt;
 	int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
 	const __be32 *pstate_ids, *pstate_freqs;
 	u32 len_ids, len_freqs;

 	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 	if (!power_mgt) {
 		pr_warn("power-mgt node not found\n");
 		return -ENODEV;
 	}

 	if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
 		pr_warn("ibm,pstate-min node not found\n");
 		return -ENODEV;
 	}

 	if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
 		pr_warn("ibm,pstate-max node not found\n");
 		return -ENODEV;
 	}

 	if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
 				 &pstate_nominal)) {
 		pr_warn("ibm,pstate-nominal not found\n");
 		return -ENODEV;
 	}
 	pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
 		pstate_nominal, pstate_max);

 	pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
 	if (!pstate_ids) {
 		pr_warn("ibm,pstate-ids not found\n");
 		return -ENODEV;
 	}

 	pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
 				      &len_freqs);
 	if (!pstate_freqs) {
 		pr_warn("ibm,pstate-frequencies-mhz not found\n");
 		return -ENODEV;
 	}

 	if (len_ids != len_freqs) {
 		pr_warn("Entries in ibm,pstate-ids and "
 			"ibm,pstate-frequencies-mhz does not match\n");
 	}

 	nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
 	if (!nr_pstates) {
 		pr_warn("No PStates found\n");
 		return -ENODEV;
 	}

 	pr_debug("NR PStates %d\n", nr_pstates);
 	for (i = 0; i < nr_pstates; i++) {
 		u32 id = be32_to_cpu(pstate_ids[i]);
 		u32 freq = be32_to_cpu(pstate_freqs[i]);

 		pr_debug("PState id %d freq %d MHz\n", id, freq);
 		powernv_freqs[i].frequency = freq * 1000; /* kHz */
 		powernv_freqs[i].driver_data = id;
 	}
 	/* End of list marker entry */
 	powernv_freqs[i].frequency = CPUFREQ_TABLE_END;

 	powernv_pstate_info.min = pstate_min;
 	powernv_pstate_info.max = pstate_max;
 	powernv_pstate_info.nominal = pstate_nominal;
 	powernv_pstate_info.nr_pstates = nr_pstates;

 	return 0;
 }

 /* Returns the CPU frequency corresponding to the pstate_id. */
 static unsigned int pstate_id_to_freq(int pstate_id)
 {
 	int i;

 	i = powernv_pstate_info.max - pstate_id;
 	if (i >= powernv_pstate_info.nr_pstates || i < 0) {
 		pr_warn("PState id %d outside of PState table, "
 			"reporting nominal id %d instead\n",
 			pstate_id, powernv_pstate_info.nominal);
 		i = powernv_pstate_info.max - powernv_pstate_info.nominal;
 	}

 	return powernv_freqs[i].frequency;
 }

 /*
  * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
  * the firmware
  */
 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
 					char *buf)
 {
 	return sprintf(buf, "%u\n",
 		pstate_id_to_freq(powernv_pstate_info.nominal));
 }

 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
 	__ATTR_RO(cpuinfo_nominal_freq);

 static struct freq_attr *powernv_cpu_freq_attr[] = {
 	&cpufreq_freq_attr_scaling_available_freqs,
 	&cpufreq_freq_attr_cpuinfo_nominal_freq,
 	NULL,
 };

 /* Helper routines */

 /* Access helpers to power mgt SPR */

 static inline unsigned long get_pmspr(unsigned long sprn)
 {
 	switch (sprn) {
 	case SPRN_PMCR:
 		return mfspr(SPRN_PMCR);

 	case SPRN_PMICR:
 		return mfspr(SPRN_PMICR);

 	case SPRN_PMSR:
 		return mfspr(SPRN_PMSR);
 	}
 	BUG();
 }

 static inline void set_pmspr(unsigned long sprn, unsigned long val)
 {
 	switch (sprn) {
 	case SPRN_PMCR:
 		mtspr(SPRN_PMCR, val);
 		return;

 	case SPRN_PMICR:
 		mtspr(SPRN_PMICR, val);
 		return;
 	}
 	BUG();
 }

 /*
  * Use objects of this type to query/update
  * pstates on a remote CPU via smp_call_function.
  */
 struct powernv_smp_call_data {
 	unsigned int freq;
 	int pstate_id;
 };

 /*
  * powernv_read_cpu_freq: Reads the current frequency on this CPU.
  *
  * Called via smp_call_function.
  *
  * Note: The caller of the smp_call_function should pass an argument of
  * the type 'struct powernv_smp_call_data *' along with this function.
  *
  * The current frequency on this CPU will be returned via
  * ((struct powernv_smp_call_data *)arg)->freq;
  */
 static void powernv_read_cpu_freq(void *arg)
 {
 	unsigned long pmspr_val;
 	s8 local_pstate_id;
 	struct powernv_smp_call_data *freq_data = arg;

 	pmspr_val = get_pmspr(SPRN_PMSR);

 	/*
 	 * The local pstate id corresponds bits 48..55 in the PMSR.
 	 * Note: Watch out for the sign!
 	 */
 	local_pstate_id = (pmspr_val >> 48) & 0xFF;
 	freq_data->pstate_id = local_pstate_id;
 	freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);

 	pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
 		raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
 		freq_data->freq);
 }

 /*
  * powernv_cpufreq_get: Returns the CPU frequency as reported by the
  * firmware for CPU 'cpu'. This value is reported through the sysfs
  * file cpuinfo_cur_freq.
  */
 static unsigned int powernv_cpufreq_get(unsigned int cpu)
 {
 	struct powernv_smp_call_data freq_data;

 	smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
 			&freq_data, 1);

 	return freq_data.freq;
 }

 /*
  * set_pstate: Sets the pstate on this CPU.
  *
  * This is called via an smp_call_function.
  *
  * The caller must ensure that freq_data is of the type
  * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
  * on this CPU should be present in freq_data->pstate_id.
  */
 static void set_pstate(void *freq_data)
 {
 	unsigned long val;
 	unsigned long pstate_ul =
 		((struct powernv_smp_call_data *) freq_data)->pstate_id;

 	val = get_pmspr(SPRN_PMCR);
 	val = val & 0x0000FFFFFFFFFFFFULL;

 	pstate_ul = pstate_ul & 0xFF;

 	/* Set both global(bits 56..63) and local(bits 48..55) PStates */
 	val = val | (pstate_ul << 56) | (pstate_ul << 48);

 	pr_debug("Setting cpu %d pmcr to %016lX\n",
 			raw_smp_processor_id(), val);
 	set_pmspr(SPRN_PMCR, val);
 }

 /*
  * get_nominal_index: Returns the index corresponding to the nominal
  * pstate in the cpufreq table
  */
 static inline unsigned int get_nominal_index(void)
 {
 	return powernv_pstate_info.max - powernv_pstate_info.nominal;
 }

 /*
  * powernv_cpufreq_target_index: Sets the frequency corresponding to
  * the cpufreq table entry indexed by new_index on the cpus in the
  * mask policy->cpus
  */
 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 					unsigned int new_index)
 {
 	struct powernv_smp_call_data freq_data;

 	if (unlikely(rebooting) && new_index != get_nominal_index())
 		return 0;

 	freq_data.pstate_id = powernv_freqs[new_index].driver_data;

 	/*
 	 * Use smp_call_function to send IPI and execute the
 	 * mtspr on target CPU.  We could do that without IPI
 	 * if current CPU is within policy->cpus (core)
 	 */
 	smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);

 	return 0;
 }

 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 {
 	int base, i;

 	base = cpu_first_thread_sibling(policy->cpu);

 	for (i = 0; i < threads_per_core; i++)
 		cpumask_set_cpu(base + i, policy->cpus);

 	return cpufreq_table_validate_and_show(policy, powernv_freqs);
 }

 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
 				unsigned long action, void *unused)
 {
 	int cpu;
 	struct cpufreq_policy cpu_policy;

 	rebooting = true;
 	for_each_online_cpu(cpu) {
 		cpufreq_get_policy(&cpu_policy, cpu);
 		powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
 	}

 	return NOTIFY_DONE;
 }

 static struct notifier_block powernv_cpufreq_reboot_nb = {
 	.notifier_call = powernv_cpufreq_reboot_notifier,
 };

 static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 {
 	struct powernv_smp_call_data freq_data;

 	freq_data.pstate_id = powernv_pstate_info.min;
 	smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
 }

 static struct cpufreq_driver powernv_cpufreq_driver = {
 	.name		= "powernv-cpufreq",
 	.flags		= CPUFREQ_CONST_LOOPS,
 	.init		= powernv_cpufreq_cpu_init,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= powernv_cpufreq_target_index,
 	.get		= powernv_cpufreq_get,
 	.stop_cpu	= powernv_cpufreq_stop_cpu,
 	.attr		= powernv_cpu_freq_attr,
 };

 static int __init powernv_cpufreq_init(void)
 {
 	int rc = 0;

 	/* Don't probe on pseries (guest) platforms */
 	if (!firmware_has_feature(FW_FEATURE_OPALv3))
 		return -ENODEV;

 	/* Discover pstates from device tree and init */
 	rc = init_powernv_pstates();
 	if (rc) {
 		pr_info("powernv-cpufreq disabled. System does not support PState control\n");
 		return rc;
 	}

 	register_reboot_notifier(&powernv_cpufreq_reboot_nb);
 	return cpufreq_register_driver(&powernv_cpufreq_driver);
 }
 module_init(powernv_cpufreq_init);

 static void __exit powernv_cpufreq_exit(void)
 {
 	unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
 	cpufreq_unregister_driver(&powernv_cpufreq_driver);
 }
 module_exit(powernv_cpufreq_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");
	/*
	* POWERNV cpufreq driver for the IBM POWER processors
	*
	* (C) Copyright IBM 2014
	*
	* Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2, or (at your option)
	* any later version.
	*
	* 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) "powernv-cpufreq: " fmt

	#include <linux/kernel.h>
	#include <linux/sysfs.h>
	#include <linux/cpumask.h>
	#include <linux/module.h>
	#include <linux/cpufreq.h>
	#include <linux/smp.h>
	#include <linux/of.h>
	#include <linux/reboot.h>

	#include <asm/cputhreads.h>
	#include <asm/firmware.h>
	#include <asm/reg.h>
	#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */

	#define POWERNV_MAX_PSTATES 256

	static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
	static bool rebooting;

	/*
	* Note: The set of pstates consists of contiguous integers, the
	* smallest of which is indicated by powernv_pstate_info.min, the
	* largest of which is indicated by powernv_pstate_info.max.
	*
	* The nominal pstate is the highest non-turbo pstate in this
	* platform. This is indicated by powernv_pstate_info.nominal.
	*/
	static struct powernv_pstate_info {
	int min;
	int max;
	int nominal;
	int nr_pstates;
	} powernv_pstate_info;

	/*
	* Initialize the freq table based on data obtained
	* from the firmware passed via device-tree
	*/
	static int init_powernv_pstates(void)
	{
	struct device_node *power_mgt;
	int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
	const __be32 pstate_ids, pstate_freqs;
	u32 len_ids, len_freqs;

	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
	if (!power_mgt) {
	pr_warn("power-mgt node not found\n");
	return -ENODEV;
	}

	if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
	pr_warn("ibm,pstate-min node not found\n");
	return -ENODEV;
	}

	if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
	pr_warn("ibm,pstate-max node not found\n");
	return -ENODEV;
	}

	if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
	&pstate_nominal)) {
	pr_warn("ibm,pstate-nominal not found\n");
	return -ENODEV;
	}
	pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
	pstate_nominal, pstate_max);

	pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
	if (!pstate_ids) {
	pr_warn("ibm,pstate-ids not found\n");
	return -ENODEV;
	}

	pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
	&len_freqs);
	if (!pstate_freqs) {
	pr_warn("ibm,pstate-frequencies-mhz not found\n");
	return -ENODEV;
	}

	if (len_ids != len_freqs) {
	pr_warn("Entries in ibm,pstate-ids and "
	"ibm,pstate-frequencies-mhz does not match\n");
	}

	nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
	if (!nr_pstates) {
	pr_warn("No PStates found\n");
	return -ENODEV;
	}

	pr_debug("NR PStates %d\n", nr_pstates);
	for (i = 0; i < nr_pstates; i++) {
	u32 id = be32_to_cpu(pstate_ids[i]);
	u32 freq = be32_to_cpu(pstate_freqs[i]);

	pr_debug("PState id %d freq %d MHz\n", id, freq);
	powernv_freqs[i].frequency = freq * 1000; /* kHz */
	powernv_freqs[i].driver_data = id;
	}
	/* End of list marker entry */
	powernv_freqs[i].frequency = CPUFREQ_TABLE_END;

	powernv_pstate_info.min = pstate_min;
	powernv_pstate_info.max = pstate_max;
	powernv_pstate_info.nominal = pstate_nominal;
	powernv_pstate_info.nr_pstates = nr_pstates;

	return 0;
	}

	/* Returns the CPU frequency corresponding to the pstate_id. */
	static unsigned int pstate_id_to_freq(int pstate_id)
	{
	int i;

	i = powernv_pstate_info.max - pstate_id;
	if (i >= powernv_pstate_info.nr_pstates \|\| i < 0) {
	pr_warn("PState id %d outside of PState table, "
	"reporting nominal id %d instead\n",
	pstate_id, powernv_pstate_info.nominal);
	i = powernv_pstate_info.max - powernv_pstate_info.nominal;
	}

	return powernv_freqs[i].frequency;
	}

	/*
	* cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
	* the firmware
	*/
	static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
	char *buf)
	{
	return sprintf(buf, "%u\n",
	pstate_id_to_freq(powernv_pstate_info.nominal));
	}

	struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
	__ATTR_RO(cpuinfo_nominal_freq);

	static struct freq_attr *powernv_cpu_freq_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	&cpufreq_freq_attr_cpuinfo_nominal_freq,
	NULL,
	};

	/* Helper routines */

	/* Access helpers to power mgt SPR */

	static inline unsigned long get_pmspr(unsigned long sprn)
	{
	switch (sprn) {
	case SPRN_PMCR:
	return mfspr(SPRN_PMCR);

	case SPRN_PMICR:
	return mfspr(SPRN_PMICR);

	case SPRN_PMSR:
	return mfspr(SPRN_PMSR);
	}
	BUG();
	}

	static inline void set_pmspr(unsigned long sprn, unsigned long val)
	{
	switch (sprn) {
	case SPRN_PMCR:
	mtspr(SPRN_PMCR, val);
	return;

	case SPRN_PMICR:
	mtspr(SPRN_PMICR, val);
	return;
	}
	BUG();
	}

	/*
	* Use objects of this type to query/update
	* pstates on a remote CPU via smp_call_function.
	*/
	struct powernv_smp_call_data {
	unsigned int freq;
	int pstate_id;
	};

	/*
	* powernv_read_cpu_freq: Reads the current frequency on this CPU.
	*
	* Called via smp_call_function.
	*
	* Note: The caller of the smp_call_function should pass an argument of
	* the type 'struct powernv_smp_call_data *' along with this function.
	*
	* The current frequency on this CPU will be returned via
	* ((struct powernv_smp_call_data *)arg)->freq;
	*/
	static void powernv_read_cpu_freq(void *arg)
	{
	unsigned long pmspr_val;
	s8 local_pstate_id;
	struct powernv_smp_call_data *freq_data = arg;

	pmspr_val = get_pmspr(SPRN_PMSR);

	/*
	* The local pstate id corresponds bits 48..55 in the PMSR.
	* Note: Watch out for the sign!
	*/
	local_pstate_id = (pmspr_val >> 48) & 0xFF;
	freq_data->pstate_id = local_pstate_id;
	freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);

	pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
	raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
	freq_data->freq);
	}

	/*
	* powernv_cpufreq_get: Returns the CPU frequency as reported by the
	* firmware for CPU 'cpu'. This value is reported through the sysfs
	* file cpuinfo_cur_freq.
	*/
	static unsigned int powernv_cpufreq_get(unsigned int cpu)
	{
	struct powernv_smp_call_data freq_data;

	smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
	&freq_data, 1);

	return freq_data.freq;
	}

	/*
	* set_pstate: Sets the pstate on this CPU.
	*
	* This is called via an smp_call_function.
	*
	* The caller must ensure that freq_data is of the type
	* (struct powernv_smp_call_data *) and the pstate_id which needs to be set
	* on this CPU should be present in freq_data->pstate_id.
	*/
	static void set_pstate(void *freq_data)
	{
	unsigned long val;
	unsigned long pstate_ul =
	((struct powernv_smp_call_data *) freq_data)->pstate_id;

	val = get_pmspr(SPRN_PMCR);
	val = val & 0x0000FFFFFFFFFFFFULL;

	pstate_ul = pstate_ul & 0xFF;

	/* Set both global(bits 56..63) and local(bits 48..55) PStates */
	val = val \| (pstate_ul << 56) \| (pstate_ul << 48);

	pr_debug("Setting cpu %d pmcr to %016lX\n",
	raw_smp_processor_id(), val);
	set_pmspr(SPRN_PMCR, val);
	}

	/*
	* get_nominal_index: Returns the index corresponding to the nominal
	* pstate in the cpufreq table
	*/
	static inline unsigned int get_nominal_index(void)
	{
	return powernv_pstate_info.max - powernv_pstate_info.nominal;
	}

	/*
	* powernv_cpufreq_target_index: Sets the frequency corresponding to
	* the cpufreq table entry indexed by new_index on the cpus in the
	* mask policy->cpus
	*/
	static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
	unsigned int new_index)
	{
	struct powernv_smp_call_data freq_data;

	if (unlikely(rebooting) && new_index != get_nominal_index())
	return 0;

	freq_data.pstate_id = powernv_freqs[new_index].driver_data;

	/*
	* Use smp_call_function to send IPI and execute the
	* mtspr on target CPU. We could do that without IPI
	* if current CPU is within policy->cpus (core)
	*/
	smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);

	return 0;
	}

	static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
	{
	int base, i;

	base = cpu_first_thread_sibling(policy->cpu);

	for (i = 0; i < threads_per_core; i++)
	cpumask_set_cpu(base + i, policy->cpus);

	return cpufreq_table_validate_and_show(policy, powernv_freqs);
	}

	static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
	unsigned long action, void *unused)
	{
	int cpu;
	struct cpufreq_policy cpu_policy;

	rebooting = true;
	for_each_online_cpu(cpu) {
	cpufreq_get_policy(&cpu_policy, cpu);
	powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
	}

	return NOTIFY_DONE;
	}

	static struct notifier_block powernv_cpufreq_reboot_nb = {
	.notifier_call = powernv_cpufreq_reboot_notifier,
	};

	static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
	{
	struct powernv_smp_call_data freq_data;

	freq_data.pstate_id = powernv_pstate_info.min;
	smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
	}

	static struct cpufreq_driver powernv_cpufreq_driver = {
	.name = "powernv-cpufreq",
	.flags = CPUFREQ_CONST_LOOPS,
	.init = powernv_cpufreq_cpu_init,
	.verify = cpufreq_generic_frequency_table_verify,
	.target_index = powernv_cpufreq_target_index,
	.get = powernv_cpufreq_get,
	.stop_cpu = powernv_cpufreq_stop_cpu,
	.attr = powernv_cpu_freq_attr,
	};

	static int __init powernv_cpufreq_init(void)
	{
	int rc = 0;

	/* Don't probe on pseries (guest) platforms */
	if (!firmware_has_feature(FW_FEATURE_OPALv3))
	return -ENODEV;

	/* Discover pstates from device tree and init */
	rc = init_powernv_pstates();
	if (rc) {
	pr_info("powernv-cpufreq disabled. System does not support PState control\n");
	return rc;
	}

	register_reboot_notifier(&powernv_cpufreq_reboot_nb);
	return cpufreq_register_driver(&powernv_cpufreq_driver);
	}
	module_init(powernv_cpufreq_init);

	static void __exit powernv_cpufreq_exit(void)
	{
	unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
	cpufreq_unregister_driver(&powernv_cpufreq_driver);
	}
	module_exit(powernv_cpufreq_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");