Commit 8a67f0ef authored by Viresh Kumar's avatar Viresh Kumar Committed by Rafael J. Wysocki
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cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue 

big LITTLE is ARM's new Architecture focussing power/performance needs of modern
world. More information about big LITTLE can be found here:

http://www.arm.com/products/processors/technologies/biglittleprocessing.php
http://lwn.net/Articles/481055/



In order to keep cpufreq support for all big LITTLE platforms simple/generic,
this patch tries to add a generic cpufreq driver layer for all big LITTLE
platforms.

The driver is divided into two parts:
- Core driver: Generic and shared across all big LITTLE SoC's
- Glue drivers: Per platform drivers providing ops to the core driver

This patch adds in a generic glue driver which would extract information from
Device Tree.

Future SoC's can either reuse the DT glue or write their own depending on the
need.

Signed-off-by: default avatarSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent eb2f50ff

Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt

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Generic ARM big LITTLE cpufreq driver's DT glue

-----------------------------------------------



This is DT specific glue layer for generic cpufreq driver for big LITTLE

systems.



Both required and optional properties listed below must be defined

under node /cpus/cpu@x. Where x is the first cpu inside a cluster.



FIXME: Cpus should boot in the order specified in DT and all cpus for a cluster

must be present contiguously. Generic DT driver will check only node 'x' for

cpu:x.



Required properties:

- operating-points: Refer to Documentation/devicetree/bindings/power/opp.txt

  for details



Optional properties:

- clock-latency: Specify the possible maximum transition latency for clock,

  in unit of nanoseconds.



Examples:



cpus {

	#address-cells = <1>;

	#size-cells = <0>;



	cpu@0 {

		compatible = "arm,cortex-a15";

		reg = <0>;

		next-level-cache = <&L2>;

		operating-points = <

			/* kHz    uV */

			792000  1100000

			396000  950000

			198000  850000

		>;

		clock-latency = <61036>; /* two CLK32 periods */

	};



	cpu@1 {

		compatible = "arm,cortex-a15";

		reg = <1>;

		next-level-cache = <&L2>;

	};



	cpu@100 {

		compatible = "arm,cortex-a7";

		reg = <100>;

		next-level-cache = <&L2>;

		operating-points = <

			/* kHz    uV */

			792000  950000

			396000  750000

			198000  450000

		>;

		clock-latency = <61036>; /* two CLK32 periods */

	};



	cpu@101 {

		compatible = "arm,cortex-a7";

		reg = <101>;

		next-level-cache = <&L2>;

	};

};

MAINTAINERS

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@@ -2206,6 +2206,17 @@ S: Maintained 
F:	drivers/cpufreq/

F:	include/linux/cpufreq.h



CPU FREQUENCY DRIVERS - ARM BIG LITTLE

M:	Viresh Kumar <viresh.kumar@linaro.org>

M:	Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

L:	cpufreq@vger.kernel.org

L:	linux-pm@vger.kernel.org

W:	http://www.arm.com/products/processors/technologies/biglittleprocessing.php

S:	Maintained

F:	drivers/cpufreq/arm_big_little.h

F:	drivers/cpufreq/arm_big_little.c

F:	drivers/cpufreq/arm_big_little_dt.c



CPUID/MSR DRIVER

M:	"H. Peter Anvin" <hpa@zytor.com>

S:	Maintained

drivers/cpufreq/Kconfig.arm

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@@ -2,6 +2,18 @@ 
# ARM CPU Frequency scaling drivers

#



config ARM_BIG_LITTLE_CPUFREQ

	tristate

	depends on ARM_CPU_TOPOLOGY



config ARM_DT_BL_CPUFREQ

	tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"

	select ARM_BIG_LITTLE_CPUFREQ

	depends on OF && HAVE_CLK

	help

	  This enables the Generic CPUfreq driver for ARM big.LITTLE platform.

	  This gets frequency tables from DT.



config ARM_OMAP2PLUS_CPUFREQ

	bool "TI OMAP2+"

	depends on ARCH_OMAP2PLUS

drivers/cpufreq/Makefile

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@@ -44,6 +44,11 @@ obj-$(CONFIG_X86_INTEL_PSTATE) += intel_pstate.o 


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

# ARM SoC drivers

obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ)	+= arm_big_little.o

# big LITTLE per platform glues. Keep DT_BL_CPUFREQ as the last entry in all big

# LITTLE drivers, so that it is probed last.

obj-$(CONFIG_ARM_DT_BL_CPUFREQ)		+= arm_big_little_dt.o



obj-$(CONFIG_UX500_SOC_DB8500)		+= dbx500-cpufreq.o

obj-$(CONFIG_ARM_S3C2416_CPUFREQ)	+= s3c2416-cpufreq.o

obj-$(CONFIG_ARM_S3C64XX_CPUFREQ)	+= s3c64xx-cpufreq.o

drivers/cpufreq/arm_big_little.c

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/*

 * ARM big.LITTLE Platforms CPUFreq support

 *

 * Copyright (C) 2013 ARM Ltd.

 * Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

 *

 * Copyright (C) 2013 Linaro.

 * Viresh Kumar <viresh.kumar@linaro.org>

 *

 * 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/of_platform.h>

#include <linux/opp.h>

#include <linux/slab.h>

#include <linux/topology.h>

#include <linux/types.h>



#include "arm_big_little.h"



/* Currently we support only two clusters */

#define MAX_CLUSTERS	2



static struct cpufreq_arm_bL_ops *arm_bL_ops;

static struct clk *clk[MAX_CLUSTERS];

static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS];

static atomic_t cluster_usage[MAX_CLUSTERS] = {ATOMIC_INIT(0), ATOMIC_INIT(0)};



static int cpu_to_cluster(int cpu)

{

	return topology_physical_package_id(cpu);

}



static unsigned int bL_cpufreq_get(unsigned int cpu)

{

	u32 cur_cluster = cpu_to_cluster(cpu);



	return clk_get_rate(clk[cur_cluster]) / 1000;

}



/* Validate policy frequency range */

static int bL_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 bL_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;

	int ret = 0;



	cur_cluster = cpu_to_cluster(policy->cpu);



	freqs.old = bL_cpufreq_get(policy->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;



	freqs.cpu = policy->cpu;



	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;



	for_each_cpu(freqs.cpu, policy->cpus)

		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);



	ret = clk_set_rate(clk[cur_cluster], freqs.new * 1000);

	if (ret) {

		pr_err("clk_set_rate failed: %d\n", ret);

		return ret;

	}



	policy->cur = freqs.new;



	for_each_cpu(freqs.cpu, policy->cpus)

		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);



	return ret;

}



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]);

		opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);

		dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);

	}

}



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_bL_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 = 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]);

	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;

}



/* Per-CPU initialization */

static int bL_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 (arm_bL_ops->get_transition_latency)

		policy->cpuinfo.transition_latency =

			arm_bL_ops->get_transition_latency(cpu_dev);

	else

		policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;



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



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



	dev_info(cpu_dev, "CPU %d initialized\n", policy->cpu);

	return 0;

}



static int bL_cpufreq_exit(struct cpufreq_policy *policy)

{

	struct device *cpu_dev;



	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;

	}



	put_cluster_clk_and_freq_table(cpu_dev);

	dev_dbg(cpu_dev, "%s: Exited, cpu: %d\n", __func__, policy->cpu);



	return 0;

}



/* Export freq_table to sysfs */

static struct freq_attr *bL_cpufreq_attr[] = {

	&cpufreq_freq_attr_scaling_available_freqs,

	NULL,

};



static struct cpufreq_driver bL_cpufreq_driver = {

	.name			= "arm-big-little",

	.flags			= CPUFREQ_STICKY,

	.verify			= bL_cpufreq_verify_policy,

	.target			= bL_cpufreq_set_target,

	.get			= bL_cpufreq_get,

	.init			= bL_cpufreq_init,

	.exit			= bL_cpufreq_exit,

	.have_multiple_policies	= true,

	.attr			= bL_cpufreq_attr,

};



int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)

{

	int ret;



	if (arm_bL_ops) {

		pr_debug("%s: Already registered: %s, exiting\n", __func__,

				arm_bL_ops->name);

		return -EBUSY;

	}



	if (!ops || !strlen(ops->name) || !ops->init_opp_table) {

		pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__);

		return -ENODEV;

	}



	arm_bL_ops = ops;



	ret = cpufreq_register_driver(&bL_cpufreq_driver);

	if (ret) {

		pr_info("%s: Failed registering platform driver: %s, err: %d\n",

				__func__, ops->name, ret);

		arm_bL_ops = NULL;

	} else {

		pr_info("%s: Registered platform driver: %s\n", __func__,

				ops->name);

	}



	return ret;

}

EXPORT_SYMBOL_GPL(bL_cpufreq_register);



void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops)

{

	if (arm_bL_ops != ops) {

		pr_err("%s: Registered with: %s, can't unregister, exiting\n",

				__func__, arm_bL_ops->name);

		return;

	}



	cpufreq_unregister_driver(&bL_cpufreq_driver);

	pr_info("%s: Un-registered platform driver: %s\n", __func__,

			arm_bL_ops->name);

	arm_bL_ops = NULL;

}

EXPORT_SYMBOL_GPL(bL_cpufreq_unregister);

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