[deliverable/linux.git] / drivers / cpufreq / powernv-cpufreq.c

/*
 * 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 <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];

/*
 * 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);
}

/*
 * 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;

	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 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,
	.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;
	}

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

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

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");
Commit	Line	Data
b3d627a5 VS	1	/*
	2	* POWERNV cpufreq driver for the IBM POWER processors
	3	*
	4	* (C) Copyright IBM 2014
	5	*
	6	* Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2, or (at your option)
	11	* any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	*/
	19
	20	#define pr_fmt(fmt) "powernv-cpufreq: " fmt
	21
	22	#include <linux/kernel.h>
	23	#include <linux/sysfs.h>
	24	#include <linux/cpumask.h>
	25	#include <linux/module.h>
	26	#include <linux/cpufreq.h>
	27	#include <linux/smp.h>
	28	#include <linux/of.h>
	29
	30	#include <asm/cputhreads.h>
6174bac8	31	#include <asm/firmware.h>
b3d627a5	32	#include <asm/reg.h>
f3cae355	33	#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
b3d627a5 VS	34
	35	#define POWERNV_MAX_PSTATES 256
	36
	37	static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
b3d627a5 VS	38
	39	/*
	40	* Note: The set of pstates consists of contiguous integers, the
	41	* smallest of which is indicated by powernv_pstate_info.min, the
	42	* largest of which is indicated by powernv_pstate_info.max.
	43	*
	44	* The nominal pstate is the highest non-turbo pstate in this
	45	* platform. This is indicated by powernv_pstate_info.nominal.
	46	*/
	47	static struct powernv_pstate_info {
	48	int min;
	49	int max;
	50	int nominal;
	51	int nr_pstates;
	52	} powernv_pstate_info;
	53
	54	/*
	55	* Initialize the freq table based on data obtained
	56	* from the firmware passed via device-tree
	57	*/
	58	static int init_powernv_pstates(void)
	59	{
	60	struct device_node *power_mgt;
	61	int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
	62	const __be32 pstate_ids, pstate_freqs;
	63	u32 len_ids, len_freqs;
	64
	65	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
	66	if (!power_mgt) {
	67	pr_warn("power-mgt node not found\n");
	68	return -ENODEV;
	69	}
	70
	71	if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
	72	pr_warn("ibm,pstate-min node not found\n");
	73	return -ENODEV;
	74	}
	75
	76	if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
	77	pr_warn("ibm,pstate-max node not found\n");
	78	return -ENODEV;
	79	}
	80
	81	if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
	82	&pstate_nominal)) {
	83	pr_warn("ibm,pstate-nominal not found\n");
	84	return -ENODEV;
	85	}
	86	pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
	87	pstate_nominal, pstate_max);
	88
	89	pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
	90	if (!pstate_ids) {
	91	pr_warn("ibm,pstate-ids not found\n");
	92	return -ENODEV;
	93	}
	94
	95	pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
	96	&len_freqs);
	97	if (!pstate_freqs) {
	98	pr_warn("ibm,pstate-frequencies-mhz not found\n");
	99	return -ENODEV;
	100	}
	101
6174bac8 VS	102	if (len_ids != len_freqs) {
	103	pr_warn("Entries in ibm,pstate-ids and "
	104	"ibm,pstate-frequencies-mhz does not match\n");
	105	}
	106
b3d627a5 VS	107	nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
	108	if (!nr_pstates) {
	109	pr_warn("No PStates found\n");
	110	return -ENODEV;
	111	}
	112
	113	pr_debug("NR PStates %d\n", nr_pstates);
	114	for (i = 0; i < nr_pstates; i++) {
	115	u32 id = be32_to_cpu(pstate_ids[i]);
	116	u32 freq = be32_to_cpu(pstate_freqs[i]);
	117
	118	pr_debug("PState id %d freq %d MHz\n", id, freq);
	119	powernv_freqs[i].frequency = freq * 1000; /* kHz */
0692c691	120	powernv_freqs[i].driver_data = id;
b3d627a5 VS	121	}
	122	/* End of list marker entry */
	123	powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
	124
	125	powernv_pstate_info.min = pstate_min;
	126	powernv_pstate_info.max = pstate_max;
	127	powernv_pstate_info.nominal = pstate_nominal;
	128	powernv_pstate_info.nr_pstates = nr_pstates;
	129
	130	return 0;
	131	}
	132
	133	/* Returns the CPU frequency corresponding to the pstate_id. */
	134	static unsigned int pstate_id_to_freq(int pstate_id)
	135	{
	136	int i;
	137
	138	i = powernv_pstate_info.max - pstate_id;
6174bac8 VS	139	if (i >= powernv_pstate_info.nr_pstates \|\| i < 0) {
	140	pr_warn("PState id %d outside of PState table, "
	141	"reporting nominal id %d instead\n",
	142	pstate_id, powernv_pstate_info.nominal);
	143	i = powernv_pstate_info.max - powernv_pstate_info.nominal;
	144	}
b3d627a5 VS	145
	146	return powernv_freqs[i].frequency;
	147	}
	148
	149	/*
	150	* cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
	151	* the firmware
	152	*/
	153	static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
	154	char *buf)
	155	{
	156	return sprintf(buf, "%u\n",
	157	pstate_id_to_freq(powernv_pstate_info.nominal));
	158	}
	159
	160	struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
	161	__ATTR_RO(cpuinfo_nominal_freq);
	162
	163	static struct freq_attr *powernv_cpu_freq_attr[] = {
	164	&cpufreq_freq_attr_scaling_available_freqs,
	165	&cpufreq_freq_attr_cpuinfo_nominal_freq,
	166	NULL,
	167	};
	168
	169	/* Helper routines */
	170
	171	/* Access helpers to power mgt SPR */
	172
	173	static inline unsigned long get_pmspr(unsigned long sprn)
	174	{
	175	switch (sprn) {
	176	case SPRN_PMCR:
	177	return mfspr(SPRN_PMCR);
	178
	179	case SPRN_PMICR:
	180	return mfspr(SPRN_PMICR);
	181
	182	case SPRN_PMSR:
	183	return mfspr(SPRN_PMSR);
	184	}
	185	BUG();
	186	}
	187
	188	static inline void set_pmspr(unsigned long sprn, unsigned long val)
	189	{
	190	switch (sprn) {
	191	case SPRN_PMCR:
	192	mtspr(SPRN_PMCR, val);
	193	return;
	194
	195	case SPRN_PMICR:
	196	mtspr(SPRN_PMICR, val);
	197	return;
	198	}
	199	BUG();
	200	}
	201
	202	/*
	203	* Use objects of this type to query/update
	204	* pstates on a remote CPU via smp_call_function.
	205	*/
	206	struct powernv_smp_call_data {
	207	unsigned int freq;
	208	int pstate_id;
209	};
210
211	/*
212	* powernv_read_cpu_freq: Reads the current frequency on this CPU.
213	*
214	* Called via smp_call_function.
215	*
216	* Note: The caller of the smp_call_function should pass an argument of
217	* the type 'struct powernv_smp_call_data *' along with this function.
218	*
219	* The current frequency on this CPU will be returned via
220	* ((struct powernv_smp_call_data *)arg)->freq;
221	*/
222	static void powernv_read_cpu_freq(void *arg)
223	{
224	unsigned long pmspr_val;
225	s8 local_pstate_id;
226	struct powernv_smp_call_data *freq_data = arg;
227
228	pmspr_val = get_pmspr(SPRN_PMSR);
229
230	/*
231	* The local pstate id corresponds bits 48..55 in the PMSR.
232	* Note: Watch out for the sign!
233	*/
234	local_pstate_id = (pmspr_val >> 48) & 0xFF;
235	freq_data->pstate_id = local_pstate_id;
236	freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
237
238	pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
239	raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
240	freq_data->freq);
241	}
242
243	/*
244	* powernv_cpufreq_get: Returns the CPU frequency as reported by the
245	* firmware for CPU 'cpu'. This value is reported through the sysfs
246	* file cpuinfo_cur_freq.
247	*/
60d1ea4e	248	static unsigned int powernv_cpufreq_get(unsigned int cpu)
b3d627a5 VS	249	{
	250	struct powernv_smp_call_data freq_data;
	251
	252	smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
	253	&freq_data, 1);
	254
	255	return freq_data.freq;
	256	}
	257
	258	/*
	259	* set_pstate: Sets the pstate on this CPU.
	260	*
	261	* This is called via an smp_call_function.
	262	*
	263	* The caller must ensure that freq_data is of the type
	264	* (struct powernv_smp_call_data *) and the pstate_id which needs to be set
	265	* on this CPU should be present in freq_data->pstate_id.
	266	*/
	267	static void set_pstate(void *freq_data)
	268	{
	269	unsigned long val;
	270	unsigned long pstate_ul =
	271	((struct powernv_smp_call_data *) freq_data)->pstate_id;
	272
	273	val = get_pmspr(SPRN_PMCR);
	274	val = val & 0x0000FFFFFFFFFFFFULL;
	275
	276	pstate_ul = pstate_ul & 0xFF;
	277
	278	/* Set both global(bits 56..63) and local(bits 48..55) PStates */
	279	val = val \| (pstate_ul << 56) \| (pstate_ul << 48);
	280
	281	pr_debug("Setting cpu %d pmcr to %016lX\n",
	282	raw_smp_processor_id(), val);
	283	set_pmspr(SPRN_PMCR, val);
	284	}
	285
	286	/*
	287	* powernv_cpufreq_target_index: Sets the frequency corresponding to
	288	* the cpufreq table entry indexed by new_index on the cpus in the
	289	* mask policy->cpus
	290	*/
	291	static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
	292	unsigned int new_index)
	293	{
	294	struct powernv_smp_call_data freq_data;
	295
0692c691	296	freq_data.pstate_id = powernv_freqs[new_index].driver_data;
b3d627a5 VS	297
	298	/*
	299	* Use smp_call_function to send IPI and execute the
	300	* mtspr on target CPU. We could do that without IPI
	301	* if current CPU is within policy->cpus (core)
	302	*/
	303	smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
	304
	305	return 0;
	306	}
	307
	308	static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
	309	{
	310	int base, i;
	311
	312	base = cpu_first_thread_sibling(policy->cpu);
	313
	314	for (i = 0; i < threads_per_core; i++)
	315	cpumask_set_cpu(base + i, policy->cpus);
	316
	317	return cpufreq_table_validate_and_show(policy, powernv_freqs);
	318	}
	319
	320	static struct cpufreq_driver powernv_cpufreq_driver = {
	321	.name = "powernv-cpufreq",
	322	.flags = CPUFREQ_CONST_LOOPS,
	323	.init = powernv_cpufreq_cpu_init,
	324	.verify = cpufreq_generic_frequency_table_verify,
	325	.target_index = powernv_cpufreq_target_index,
	326	.get = powernv_cpufreq_get,
	327	.attr = powernv_cpu_freq_attr,
	328	};
	329
	330	static int __init powernv_cpufreq_init(void)
	331	{
	332	int rc = 0;
	333
6174bac8 VS	334	/* Don't probe on pseries (guest) platforms */
	335	if (!firmware_has_feature(FW_FEATURE_OPALv3))
	336	return -ENODEV;
	337
b3d627a5 VS	338	/* Discover pstates from device tree and init */
	339	rc = init_powernv_pstates();
	340	if (rc) {
	341	pr_info("powernv-cpufreq disabled. System does not support PState control\n");
	342	return rc;
	343	}
	344
	345	return cpufreq_register_driver(&powernv_cpufreq_driver);
	346	}
	347	module_init(powernv_cpufreq_init);
	348
	349	static void __exit powernv_cpufreq_exit(void)
	350	{
	351	cpufreq_unregister_driver(&powernv_cpufreq_driver);
	352	}
	353	module_exit(powernv_cpufreq_exit);
	354
	355	MODULE_LICENSE("GPL");
	356	MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");