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Commit e7ddf4b7 authored by Srinidhi Kasagar's avatar Srinidhi Kasagar Committed by Len Brown
Browse files

cpufreq: Add SFI based cpufreq driver support 



This adds the SFI based cpu freq driver for some of the Intel's
Silvermont based Atom architectures like Z34xx and Z35xx.

Signed-off-by: default avatarRudramuni, Vishwesh M <vishwesh.m.rudramuni@intel.com>
Signed-off-by: default avatarSrinidhi Kasagar <srinidhi.kasagar@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 108cc2e7

arch/x86/include/uapi/asm/msr-index.h

+1 −0
Original line number Diff line number Diff line
@@ -318,6 +318,7 @@ 


#define MSR_IA32_PERF_STATUS		0x00000198

#define MSR_IA32_PERF_CTL		0x00000199

#define INTEL_PERF_CTL_MASK		0xffff

#define MSR_AMD_PSTATE_DEF_BASE		0xc0010064

#define MSR_AMD_PERF_STATUS		0xc0010063

#define MSR_AMD_PERF_CTL		0xc0010062

drivers/cpufreq/Kconfig.x86

+10 −0
Original line number Diff line number Diff line
@@ -57,6 +57,16 @@ config X86_ACPI_CPUFREQ_CPB 
	  By enabling this option the acpi_cpufreq driver provides the old

	  entry in addition to the new boost ones, for compatibility reasons.



config X86_SFI_CPUFREQ

	tristate "SFI Performance-States driver"

	depends on X86_INTEL_MID && SFI

	help

	  This adds a CPUFreq driver for some Silvermont based Intel Atom

	  architectures like Z34xx and Z35xx which enumerate processor

	  performance states through SFI.



	  If in doubt, say N.



config ELAN_CPUFREQ

	tristate "AMD Elan SC400 and SC410"

	depends on MELAN

drivers/cpufreq/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ obj-$(CONFIG_X86_P4_CLOCKMOD) += p4-clockmod.o 
obj-$(CONFIG_X86_CPUFREQ_NFORCE2)	+= cpufreq-nforce2.o

obj-$(CONFIG_X86_INTEL_PSTATE)		+= intel_pstate.o

obj-$(CONFIG_X86_AMD_FREQ_SENSITIVITY)	+= amd_freq_sensitivity.o

obj-$(CONFIG_X86_SFI_CPUFREQ)		+= sfi-cpufreq.o



##################################################################################

# ARM SoC drivers

drivers/cpufreq/sfi-cpufreq.c

0 → 100644
+136 −0
Original line number Diff line number Diff line 
/*

 *  SFI Performance States Driver

 *

 *  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 of the License.

 *

 *  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.

 *

 *  Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>

 *  Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com>

 */



#include <linux/cpufreq.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/sfi.h>

#include <linux/slab.h>

#include <linux/smp.h>



#include <asm/msr.h>



struct cpufreq_frequency_table *freq_table;

static struct sfi_freq_table_entry *sfi_cpufreq_array;

static int num_freq_table_entries;



static int sfi_parse_freq(struct sfi_table_header *table)

{

	struct sfi_table_simple *sb;

	struct sfi_freq_table_entry *pentry;

	int totallen;



	sb = (struct sfi_table_simple *)table;

	num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb,

			struct sfi_freq_table_entry);

	if (num_freq_table_entries <= 1) {

		pr_err("No p-states discovered\n");

		return -ENODEV;

	}



	pentry = (struct sfi_freq_table_entry *)sb->pentry;

	totallen = num_freq_table_entries * sizeof(*pentry);



	sfi_cpufreq_array = kzalloc(totallen, GFP_KERNEL);

	if (!sfi_cpufreq_array)

		return -ENOMEM;



	memcpy(sfi_cpufreq_array, pentry, totallen);



	return 0;

}



static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)

{

	unsigned int next_perf_state = 0; /* Index into perf table */

	u32 lo, hi;



	next_perf_state = policy->freq_table[index].driver_data;



	rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi);

	lo = (lo & ~INTEL_PERF_CTL_MASK) |

		((u32) sfi_cpufreq_array[next_perf_state].ctrl_val &

		INTEL_PERF_CTL_MASK);

	wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi);



	return 0;

}



static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy)

{

	policy->shared_type = CPUFREQ_SHARED_TYPE_HW;

	policy->cpuinfo.transition_latency = 100000;	/* 100us */



	return cpufreq_table_validate_and_show(policy, freq_table);

}



static struct cpufreq_driver sfi_cpufreq_driver = {

	.flags		= CPUFREQ_CONST_LOOPS,

	.verify		= cpufreq_generic_frequency_table_verify,

	.target_index	= sfi_cpufreq_target,

	.init		= sfi_cpufreq_cpu_init,

	.name		= "sfi-cpufreq",

	.attr		= cpufreq_generic_attr,

};



static int __init sfi_cpufreq_init(void)

{

	int ret, i;



	/* parse the freq table from SFI */

	ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);

	if (ret)

		return ret;



	freq_table = kzalloc(sizeof(*freq_table) *

			(num_freq_table_entries + 1), GFP_KERNEL);

	if (!freq_table) {

		ret = -ENOMEM;

		goto err_free_array;

	}



	for (i = 0; i < num_freq_table_entries; i++) {

		freq_table[i].driver_data = i;

		freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;

	}

	freq_table[i].frequency = CPUFREQ_TABLE_END;



	ret = cpufreq_register_driver(&sfi_cpufreq_driver);

	if (ret)

		goto err_free_tbl;



	return ret;



err_free_tbl:

	kfree(freq_table);

err_free_array:

	kfree(sfi_cpufreq_array);

	return ret;

}

late_initcall(sfi_cpufreq_init);



static void __exit sfi_cpufreq_exit(void)

{

	cpufreq_unregister_driver(&sfi_cpufreq_driver);

	kfree(freq_table);

	kfree(sfi_cpufreq_array);

}

module_exit(sfi_cpufreq_exit);



MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");

MODULE_DESCRIPTION("SFI Performance-States Driver");

MODULE_LICENSE("GPL");