Commit 02361418 authored by Amit Daniel Kachhap's avatar Amit Daniel Kachhap Committed by Zhang Rui

thermal: add generic cpufreq cooling implementation

This patchset introduces a new generic cooling device based on cpufreq
that can be used on non-ACPI platforms.  As a proof of concept, we have
drivers for the following platforms using this mechanism now:

 * Samsung Exynos (Exynos4 and Exynos5) in the current patchset.
 * Freescale i.MX (git://git.linaro.org/people/amitdanielk/linux.git imx6q_thermal)

There is a small change in cpufreq cooling registration APIs, so a minor
change is needed for Freescale platforms.

Brief Description:

1) The generic cooling devices code is placed inside driver/thermal/*
   as placing inside acpi folder will need un-necessary enabling of acpi
   code.  This code is architecture independent.

2) This patchset adds generic cpu cooling low level implementation
   through frequency clipping.  In future, other cpu related cooling
   devices may be added here.  An ACPI version of this already exists
   (drivers/acpi/processor_thermal.c) .But this will be useful for
   platforms like ARM using the generic thermal interface along with the
   generic cpu cooling devices.  The cooling device registration API's
   return cooling device pointers which can be easily binded with the
   thermal zone trip points.  The important APIs exposed are,

   a) struct thermal_cooling_device *cpufreq_cooling_register(
        struct cpumask *clip_cpus)
   b) void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)

3) Samsung exynos platform thermal implementation is done using the
   generic cpu cooling APIs and the new trip type.  The temperature sensor
   driver present in the hwmon folder(registered as hwmon driver) is moved
   to thermal folder and registered as a thermal driver.

A simple data/control flow diagrams is shown below,

Core Linux thermal <----->  Exynos thermal interface <----- Temperature Sensor
          |                             |
         \|/                            |
  Cpufreq cooling device <---------------

TODO:
*Will send the DT enablement patches later after the driver is merged.

This patch:

Add support for generic cpu thermal cooling low level implementations
using frequency scaling up/down based on the registration parameters.
Different cpu related cooling devices can be registered by the user and
the binding of these cooling devices to the corresponding trip points can
be easily done as the registration APIs return the cooling device pointer.
The user of these APIs are responsible for passing clipping frequency .
The drivers can also register to recieve notification about any cooling
action called.

[akpm@linux-foundation.org: fix comment layout]
Signed-off-by: default avatarAmit Daniel Kachhap <amit.kachhap@linaro.org>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: SangWook Ju <sw.ju@samsung.com>
Cc: Durgadoss <durgadoss.r@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAmit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
parent a7a3b8c8
CPU cooling APIs How To
===================================
Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
Updated: 12 May 2012
Copyright (c) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
0. Introduction
The generic cpu cooling(freq clipping) provides registration/unregistration APIs
to the caller. The binding of the cooling devices to the trip point is left for
the user. The registration APIs returns the cooling device pointer.
1. cpu cooling APIs
1.1 cpufreq registration/unregistration APIs
1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
struct cpumask *clip_cpus)
This interface function registers the cpufreq cooling device with the name
"thermal-cpufreq-%x". This api can support multiple instances of cpufreq
cooling devices.
clip_cpus: cpumask of cpus where the frequency constraints will happen.
1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
This interface function unregisters the "thermal-cpufreq-%x" cooling device.
cdev: Cooling device pointer which has to be unregistered.
...@@ -19,6 +19,17 @@ config THERMAL_HWMON ...@@ -19,6 +19,17 @@ config THERMAL_HWMON
depends on HWMON=y || HWMON=THERMAL depends on HWMON=y || HWMON=THERMAL
default y default y
config CPU_THERMAL
bool "generic cpu cooling support"
depends on THERMAL && CPU_FREQ
help
This implements the generic cpu cooling mechanism through frequency
reduction, cpu hotplug and any other ways of reducing temperature. An
ACPI version of this already exists(drivers/acpi/processor_thermal.c).
This will be useful for platforms using the generic thermal interface
and not the ACPI interface.
If you want this support, you should say Y here.
config SPEAR_THERMAL config SPEAR_THERMAL
bool "SPEAr thermal sensor driver" bool "SPEAr thermal sensor driver"
depends on THERMAL depends on THERMAL
......
...@@ -3,5 +3,6 @@ ...@@ -3,5 +3,6 @@
# #
obj-$(CONFIG_THERMAL) += thermal_sys.o obj-$(CONFIG_THERMAL) += thermal_sys.o
obj-$(CONFIG_CPU_THERMAL) += cpu_cooling.o
obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o
obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o
This diff is collapsed.
/*
* linux/include/linux/cpu_cooling.h
*
* Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
* Copyright (C) 2012 Amit Daniel <amit.kachhap@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.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#ifndef __CPU_COOLING_H__
#define __CPU_COOLING_H__
#include <linux/thermal.h>
#define CPUFREQ_COOLING_START 0
#define CPUFREQ_COOLING_STOP 1
#ifdef CONFIG_CPU_THERMAL
/**
* cpufreq_cooling_register - function to create cpufreq cooling device.
* @clip_cpus: cpumask of cpus where the frequency constraints will happen
*/
struct thermal_cooling_device *cpufreq_cooling_register(
struct cpumask *clip_cpus);
/**
* cpufreq_cooling_unregister - function to remove cpufreq cooling device.
* @cdev: thermal cooling device pointer.
*/
void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
#else /* !CONFIG_CPU_THERMAL */
static inline struct thermal_cooling_device *cpufreq_cooling_register(
struct cpumask *clip_cpus)
{
return NULL;
}
static inline void cpufreq_cooling_unregister(
struct thermal_cooling_device *cdev)
{
return;
}
#endif /* CONFIG_CPU_THERMAL */
#endif /* __CPU_COOLING_H__ */
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