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Commit 5477fb3b authored by Ashwin Chaugule's avatar Ashwin Chaugule Committed by Rafael J. Wysocki
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ACPI / CPPC: Add a CPUFreq driver for use with CPPC 



This driver utilizes the methods introduced in a previous
patch titled - "ACPI: Introduce CPU performance controls using CPPC"
and enables usage with existing CPUFreq governors.

Signed-off-by: default avatarAshwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: default avatarAl Stone <al.stone@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 337aadff

drivers/cpufreq/Kconfig.arm

+17 −0
Original line number Diff line number Diff line
@@ -227,3 +227,20 @@ config ARM_PXA2xx_CPUFREQ 
	  This add the CPUFreq driver support for Intel PXA2xx SOCs.



	  If in doubt, say N.



config ACPI_CPPC_CPUFREQ

	tristate "CPUFreq driver based on the ACPI CPPC spec"

	depends on ACPI

	select ACPI_CPPC_LIB

	default n

	help

	  This adds a CPUFreq driver which uses CPPC methods

	  as described in the ACPIv5.1 spec. CPPC stands for

	  Collaborative Processor Performance Controls. It

	  is based on an abstract continuous scale of CPU

	  performance values which allows the remote power

	  processor to flexibly optimize for power and

	  performance. CPPC relies on power management firmware

	  support for its operation.



	  If in doubt, say N.

drivers/cpufreq/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -76,6 +76,8 @@ obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o 
obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o

obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o

obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o

obj-$(CONFIG_ACPI_CPPC_CPUFREQ) += cppc_cpufreq.o





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

# PowerPC platform drivers

drivers/cpufreq/cppc_cpufreq.c

0 → 100644
+176 −0
Original line number Diff line number Diff line 
/*

 * CPPC (Collaborative Processor Performance Control) driver for

 * interfacing with the CPUfreq layer and governors. See

 * cppc_acpi.c for CPPC specific methods.

 *

 * (C) Copyright 2014, 2015 Linaro Ltd.

 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>

 *

 * 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; version 2

 * of the License.

 */



#define pr_fmt(fmt)	"CPPC Cpufreq:"	fmt



#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/delay.h>

#include <linux/cpu.h>

#include <linux/cpufreq.h>

#include <linux/vmalloc.h>



#include <acpi/cppc_acpi.h>



/*

 * These structs contain information parsed from per CPU

 * ACPI _CPC structures.

 * e.g. For each CPU the highest, lowest supported

 * performance capabilities, desired performance level

 * requested etc.

 */

static struct cpudata **all_cpu_data;



static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,

		unsigned int target_freq,

		unsigned int relation)

{

	struct cpudata *cpu;

	struct cpufreq_freqs freqs;

	int ret = 0;



	cpu = all_cpu_data[policy->cpu];



	cpu->perf_ctrls.desired_perf = target_freq;

	freqs.old = policy->cur;

	freqs.new = target_freq;



	cpufreq_freq_transition_begin(policy, &freqs);

	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);

	cpufreq_freq_transition_end(policy, &freqs, ret != 0);



	if (ret)

		pr_debug("Failed to set target on CPU:%d. ret:%d\n",

				cpu->cpu, ret);



	return ret;

}



static int cppc_verify_policy(struct cpufreq_policy *policy)

{

	cpufreq_verify_within_cpu_limits(policy);

	return 0;

}



static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)

{

	int cpu_num = policy->cpu;

	struct cpudata *cpu = all_cpu_data[cpu_num];

	int ret;



	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;



	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);

	if (ret)

		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",

				cpu->perf_caps.lowest_perf, cpu_num, ret);

}



static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)

{

	struct cpudata *cpu;

	unsigned int cpu_num = policy->cpu;

	int ret = 0;



	cpu = all_cpu_data[policy->cpu];



	cpu->cpu = cpu_num;

	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);



	if (ret) {

		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",

				cpu_num, ret);

		return ret;

	}



	policy->min = cpu->perf_caps.lowest_perf;

	policy->max = cpu->perf_caps.highest_perf;

	policy->cpuinfo.min_freq = policy->min;

	policy->cpuinfo.max_freq = policy->max;



	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)

		cpumask_copy(policy->cpus, cpu->shared_cpu_map);

	else {

		/* Support only SW_ANY for now. */

		pr_debug("Unsupported CPU co-ord type\n");

		return -EFAULT;

	}



	cpumask_set_cpu(policy->cpu, policy->cpus);

	cpu->cur_policy = policy;



	/* Set policy->cur to max now. The governors will adjust later. */

	policy->cur = cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;



	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);

	if (ret)

		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",

				cpu->perf_caps.highest_perf, cpu_num, ret);



	return ret;

}



static struct cpufreq_driver cppc_cpufreq_driver = {

	.flags = CPUFREQ_CONST_LOOPS,

	.verify = cppc_verify_policy,

	.target = cppc_cpufreq_set_target,

	.init = cppc_cpufreq_cpu_init,

	.stop_cpu = cppc_cpufreq_stop_cpu,

	.name = "cppc_cpufreq",

};



static int __init cppc_cpufreq_init(void)

{

	int i, ret = 0;

	struct cpudata *cpu;



	if (acpi_disabled)

		return -ENODEV;



	all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);

	if (!all_cpu_data)

		return -ENOMEM;



	for_each_possible_cpu(i) {

		all_cpu_data[i] = kzalloc(sizeof(struct cpudata), GFP_KERNEL);

		if (!all_cpu_data[i])

			goto out;



		cpu = all_cpu_data[i];

		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))

			goto out;

	}



	ret = acpi_get_psd_map(all_cpu_data);

	if (ret) {

		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");

		goto out;

	}



	ret = cpufreq_register_driver(&cppc_cpufreq_driver);

	if (ret)

		goto out;



	return ret;



out:

	for_each_possible_cpu(i)

		if (all_cpu_data[i])

			kfree(all_cpu_data[i]);



	kfree(all_cpu_data);

	return -ENODEV;

}



late_initcall(cppc_cpufreq_init);