Re: [linux-pm] [PATCH v6 1/6] thermal: add generic cpufreq cooling implementation

Amit Kachhap
2012-08-17T03:43:04Z

On 16 August 2012 20:22, Valentin, Eduardo <eduardo.valentin@ti.com> wrote:
>
> Amit,
>
> Thanks again for keeping this up.
>
> On Thu, Aug 16, 2012 at 2:41 PM, Amit Daniel Kachhap
> <amit.kachhap@linaro.org> wrote:
> > 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)
>
> FYI, the OMAP code is under drivers/staging/omap-thermal/. The file
> omap-thermal-common.c is the one which is using your generic cooling
> device. But it needs to be updated accordingly to the API change you
> mention.
>
> >
> > 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: Amit 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: Andrew Morton <akpm@linux-foundation.org>
> > Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
>
>
> Reviewed-by: Eduardo Valentin <eduardo.valentin@ti.com>

Thanks Eduardo .

>
>
> > ---
> > Documentation/thermal/cpu-cooling-api.txt | 52 +++
> > drivers/thermal/Kconfig | 11 +
> > drivers/thermal/Makefile | 1 +
> > drivers/thermal/cpu_cooling.c | 512
> > +++++++++++++++++++++++++++++
> > include/linux/cpu_cooling.h | 79 +++++
> > 5 files changed, 655 insertions(+), 0 deletions(-)
> > create mode 100644 Documentation/thermal/cpu-cooling-api.txt
> > create mode 100644 drivers/thermal/cpu_cooling.c
> > create mode 100644 include/linux/cpu_cooling.h
> >
> > diff --git a/Documentation/thermal/cpu-cooling-api.txt
> > b/Documentation/thermal/cpu-cooling-api.txt
> > new file mode 100644
> > index 0000000..a1f2a6b
> > --- /dev/null
> > +++ b/Documentation/thermal/cpu-cooling-api.txt
> > @@ -0,0 +1,52 @@
> > +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.
> > +
> > +
> > +1.2 CPU cooling action notifier register/unregister interface
> > +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
> > + unsigned int list)
> > +
> > + This interface registers a driver with cpu cooling layer. The
> > driver will
> > + be notified when any cpu cooling action is called.
> > +
> > + nb: notifier function to register
> > + list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> > +
> > +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
> > + unsigned int list)
> > +
> > + This interface registers a driver with cpu cooling layer. The
> > driver will
> > + be notified when any cpu cooling action is called.
> > +
> > + nb: notifier function to register
> > + list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> > diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> > index 7dd8c34..996003b 100644
> > --- a/drivers/thermal/Kconfig
> > +++ b/drivers/thermal/Kconfig
> > @@ -19,6 +19,17 @@ config THERMAL_HWMON
> > depends on HWMON=y || HWMON=THERMAL
> > 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
> > bool "SPEAr thermal sensor driver"
> > depends on THERMAL
> > diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> > index fd9369a..aae59ad 100644
> > --- a/drivers/thermal/Makefile
> > +++ b/drivers/thermal/Makefile
> > @@ -3,5 +3,6 @@
> > #
> >
> > obj-$(CONFIG_THERMAL) += thermal_sys.o
> > +obj-$(CONFIG_CPU_THERMAL) += cpu_cooling.o
> > obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o
> > obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o
> > diff --git a/drivers/thermal/cpu_cooling.c
> > b/drivers/thermal/cpu_cooling.c
> > new file mode 100644
> > index 0000000..c42e557
> > --- /dev/null
> > +++ b/drivers/thermal/cpu_cooling.c
> > @@ -0,0 +1,512 @@
> > +/*
> > + * linux/drivers/thermal/cpu_cooling.c
> > + *
> > + * 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.
> > + *
> > + *
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > + */
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/thermal.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/cpufreq.h>
> > +#include <linux/err.h>
> > +#include <linux/slab.h>
> > +#include <linux/cpu.h>
> > +#include <linux/cpu_cooling.h>
> > +
> > +/**
> > + * struct cpufreq_cooling_device
> > + * @id: unique integer value corresponding to each
> > cpufreq_cooling_device
> > + * registered.
> > + * @cool_dev: thermal_cooling_device pointer to keep track of the the
> > + * egistered cooling device.
> > + * @cpufreq_state: integer value representing the current state of
> > cpufreq
> > + * cooling devices.
> > + * @cpufreq_val: integer value representing the absolute value of the
> > clipped
> > + * frequency.
> > + * @allowed_cpus: all the cpus involved for this
> > cpufreq_cooling_device.
> > + * @node: list_head to link all cpufreq_cooling_device together.
> > + *
> > + * This structure is required for keeping information of each
> > + * cpufreq_cooling_device registered as a list whose head is
> > represented by
> > + * cooling_cpufreq_list. In order to prevent corruption of this list a
> > + * mutex lock cooling_cpufreq_lock is used.
> > + */
> > +struct cpufreq_cooling_device {
> > + int id;
> > + struct thermal_cooling_device *cool_dev;
> > + unsigned int cpufreq_state;
> > + unsigned int cpufreq_val;
> > + struct cpumask allowed_cpus;
> > + struct list_head node;
> > +};
> > +static LIST_HEAD(cooling_cpufreq_list);
> > +static DEFINE_IDR(cpufreq_idr);
> > +
> > +static struct mutex cooling_cpufreq_lock;
> > +
> > +/* notify_table passes value to the CPUFREQ_ADJUST callback function.
> > */
> > +#define NOTIFY_INVALID NULL
> > +struct cpufreq_cooling_device *notify_device;
> > +
> > +/* Head of the blocking notifier chain to inform about frequency
> > clamping */
> > +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
> > +
> > +/**
> > + * get_idr - function to get a unique id.
> > + * @idr: struct idr * handle used to create a id.
> > + * @id: int * value generated by this function.
> > + */
> > +static int get_idr(struct idr *idr, int *id)
> > +{
> > + int err;
> > +again:
> > + if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
> > + return -ENOMEM;
> > +
> > + mutex_lock(&cooling_cpufreq_lock);
> > + err = idr_get_new(idr, NULL, id);
> > + mutex_unlock(&cooling_cpufreq_lock);
> > +
> > + if (unlikely(err == -EAGAIN))
> > + goto again;
> > + else if (unlikely(err))
> > + return err;
> > +
> > + *id = *id & MAX_ID_MASK;
> > + return 0;
> > +}
> > +
> > +/**
> > + * release_idr - function to free the unique id.
> > + * @idr: struct idr * handle used for creating the id.
> > + * @id: int value representing the unique id.
> > + */
> > +static void release_idr(struct idr *idr, int id)
> > +{
> > + mutex_lock(&cooling_cpufreq_lock);
> > + idr_remove(idr, id);
> > + mutex_unlock(&cooling_cpufreq_lock);
> > +}
> > +
> > +/**
> > + * cputherm_register_notifier - Register a notifier with cpu cooling
> > interface.
> > + * @nb: struct notifier_block * with callback info.
> > + * @list: integer value for which notification is needed. possible
> > values are
> > + * CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> > + *
> > + * This exported function registers a driver with cpu cooling layer.
> > The driver
> > + * will be notified when any cpu cooling action is called.
> > + */
> > +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> > list)
> > +{
> > + int ret = 0;
> > +
> > + switch (list) {
> > + case CPUFREQ_COOLING_START:
> > + case CPUFREQ_COOLING_STOP:
> > + ret = blocking_notifier_chain_register(
> > + &cputherm_state_notifier_list, nb);
> > + break;
> > + default:
> > + ret = -EINVAL;
> > + }
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(cputherm_register_notifier);
> > +
> > +/**
> > + * cputherm_unregister_notifier - Un-register a notifier.
> > + * @nb: struct notifier_block * with callback info.
> > + * @list: integer value for which notification is needed. values
> > possible are
> > + * CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
> > + *
> > + * This exported function un-registers a driver with cpu cooling layer.
> > + */
> > +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned
> > int list)
> > +{
> > + int ret = 0;
> > +
> > + switch (list) {
> > + case CPUFREQ_COOLING_START:
> > + case CPUFREQ_COOLING_STOP:
> > + ret = blocking_notifier_chain_unregister(
> > + &cputherm_state_notifier_list, nb);
> > + break;
> > + default:
> > + ret = -EINVAL;
> > + }
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(cputherm_unregister_notifier);
> > +
> > +/* Below code defines functions to be used for cpufreq as cooling
> > device */
> > +
> > +/**
> > + * is_cpufreq_valid - function to check if a cpu has frequency
> > transition policy.
> > + * @cpu: cpu for which check is needed.
> > + */
> > +static int is_cpufreq_valid(int cpu)
> > +{
> > + struct cpufreq_policy policy;
> > + return !cpufreq_get_policy(&policy, cpu);
> > +}
> > +
> > +/**
> > + * get_cpu_frequency - get the absolute value of frequency from level.
> > + * @cpu: cpu for which frequency is fetched.
> > + * @level: level of frequency of the CPU
> > + * e.g level=1 --> 1st MAX FREQ, LEVEL=2 ---> 2nd MAX FREQ, ....
> > etc
> > + */
> > +static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long
> > level)
>
>
> I like this. With previous implemention I had to write a similar
> function, but with output of the required freq clip table. Now that
> you have the freq walk here it simplifies the zone setup code.
>
>
> > +{
> > + int ret = 0, i = 0;
> > + unsigned long level_index;
> > + bool descend = false;
> > + struct cpufreq_frequency_table *table =
> > +
> > cpufreq_frequency_get_table(cpu);
> > + if (!table)
> > + return ret;
> > +
> > + while (table[i].frequency != CPUFREQ_TABLE_END) {
> > + if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
> > + continue;
> > +
> > + /*check if table in ascending or descending order*/
> > + if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
> > + (table[i + 1].frequency < table[i].frequency)
> > + && !descend) {
> > + descend = true;
> > + }
> > +
> > + /*return if level matched and table in descending
> > order*/
> > + if (descend && i == level)
> > + return table[i].frequency;
> > + i++;
> > + }
> > + i--;
> > +
> > + if (level > i || descend)
> > + return ret;
> > + level_index = i - level;
> > +
> > + /*Scan the table in reverse order and match the level*/
> > + while (i >= 0) {
> > + if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
> > + continue;
> > + /*return if level matched*/
> > + if (i == level_index)
> > + return table[i].frequency;
> > + i--;
> > + }
> > + return ret;
> > +}
> > +
> > +/**
> > + * cpufreq_apply_cooling - function to apply frequency clipping.
> > + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> > + * clipping data.
> > + * @cooling_state: value of the cooling state.
> > + */
> > +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
> > *cpufreq_device,
> > + unsigned long cooling_state)
> > +{
> > + unsigned int event, cpuid, clip_freq;
> > + struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
> > + unsigned int cpu = cpumask_any(maskPtr);
> > +
> > +
> > + /* Check if the old cooling action is same as new cooling action
> > */
> > + if (cpufreq_device->cpufreq_state == cooling_state)
> > + return 0;
> > +
> > + clip_freq = get_cpu_frequency(cpu, cooling_state);
> > + if (!clip_freq)
> > + return -EINVAL;
> > +
> > + cpufreq_device->cpufreq_state = cooling_state;
> > + cpufreq_device->cpufreq_val = clip_freq;
> > + notify_device = cpufreq_device;
> > +
> > + if (cooling_state != 0)
> > + event = CPUFREQ_COOLING_START;
> > + else
> > + event = CPUFREQ_COOLING_STOP;
> > +
> > + blocking_notifier_call_chain(&cputherm_state_notifier_list,
> > + event, &clip_freq);
> > +
> > + for_each_cpu(cpuid, maskPtr) {
> > + if (is_cpufreq_valid(cpuid))
> > + cpufreq_update_policy(cpuid);
> > + }
> > +
> > + notify_device = NOTIFY_INVALID;
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * cpufreq_thermal_notifier - notifier callback for cpufreq policy
> > change.
> > + * @nb: struct notifier_block * with callback info.
> > + * @event: value showing cpufreq event for which this function invoked.
> > + * @data: callback-specific data
> > + */
> > +static int cpufreq_thermal_notifier(struct notifier_block *nb,
> > + unsigned long event, void *data)
> > +{
> > + struct cpufreq_policy *policy = data;
> > + unsigned long max_freq = 0;
> > +
> > + if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
> > + return 0;
> > +
> > + if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
> > + max_freq = notify_device->cpufreq_val;
> > +
> > + /* Never exceed user_policy.max*/
> > + if (max_freq > policy->user_policy.max)
> > + max_freq = policy->user_policy.max;
> > +
> > + if (policy->max != max_freq)
> > + cpufreq_verify_within_limits(policy, 0, max_freq);
> > +
> > + return 0;
> > +}
> > +
> > +/*
> > + * cpufreq cooling device callback functions are defined below
> > + */
> > +
> > +/**
> > + * cpufreq_get_max_state - callback function to get the max cooling
> > state.
> > + * @cdev: thermal cooling device pointer.
> > + * @state: fill this variable with the max cooling state.
> > + */
> > +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
> > + unsigned long *state)
> > +{
> > + int ret = -EINVAL, i = 0;
> > + struct cpufreq_cooling_device *cpufreq_device;
> > + struct cpumask *maskPtr;
> > + unsigned int cpu;
> > + struct cpufreq_frequency_table *table;
> > +
> > + mutex_lock(&cooling_cpufreq_lock);
> > + list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
> > {
> > + if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> > + break;
> > + }
> > + if (cpufreq_device == NULL)
> > + goto return_get_max_state;
> > +
> > + maskPtr = &cpufreq_device->allowed_cpus;
> > + cpu = cpumask_any(maskPtr);
> > + table = cpufreq_frequency_get_table(cpu);
> > + if (!table) {
> > + *state = 0;
> > + ret = 0;
> > + goto return_get_max_state;
> > + }
> > +
> > + while (table[i].frequency != CPUFREQ_TABLE_END) {
> > + if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
> > + continue;
> > + i++;
> > + }
> > + if (i > 0) {
> > + *state = --i;
> > + ret = 0;
> > + }
> > +
> > +return_get_max_state:
> > + mutex_unlock(&cooling_cpufreq_lock);
> > + return ret;
> > +}
> > +
> > +/**
> > + * cpufreq_get_cur_state - callback function to get the current cooling
> > state.
> > + * @cdev: thermal cooling device pointer.
> > + * @state: fill this variable with the current cooling state.
> > + */
> > +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
> > + unsigned long *state)
> > +{
> > + int ret = -EINVAL;
> > + struct cpufreq_cooling_device *cpufreq_device;
> > +
> > + mutex_lock(&cooling_cpufreq_lock);
> > + list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
> > {
> > + if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> > {
> > + *state = cpufreq_device->cpufreq_state;
> > + ret = 0;
> > + break;
> > + }
> > + }
> > + mutex_unlock(&cooling_cpufreq_lock);
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * cpufreq_set_cur_state - callback function to set the current cooling
> > state.
> > + * @cdev: thermal cooling device pointer.
> > + * @state: set this variable to the current cooling state.
> > + */
> > +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> > + unsigned long state)
> > +{
> > + int ret = -EINVAL;
> > + struct cpufreq_cooling_device *cpufreq_device;
> > +
> > + mutex_lock(&cooling_cpufreq_lock);
> > + list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
> > {
> > + if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> > {
> > + ret = 0;
> > + break;
> > + }
> > + }
> > + if (!ret)
> > + ret = cpufreq_apply_cooling(cpufreq_device, state);
> > +
> > + mutex_unlock(&cooling_cpufreq_lock);
> > +
> > + return ret;
> > +}
> > +
> > +/* Bind cpufreq callbacks to thermal cooling device ops */
> > +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> > + .get_max_state = cpufreq_get_max_state,
> > + .get_cur_state = cpufreq_get_cur_state,
> > + .set_cur_state = cpufreq_set_cur_state,
> > +};
> > +
> > +/* Notifier for cpufreq policy change */
> > +static struct notifier_block thermal_cpufreq_notifier_block = {
> > + .notifier_call = cpufreq_thermal_notifier,
> > +};
> > +
> > +/**
> > + * 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)
> > +{
> > + struct thermal_cooling_device *cool_dev;
> > + struct cpufreq_cooling_device *cpufreq_dev = NULL;
> > + unsigned int cpufreq_dev_count = 0, min = 0, max = 0;
> > + char dev_name[THERMAL_NAME_LENGTH];
> > + int ret = 0, id = 0, i;
> > + struct cpufreq_policy policy;
> > +
> > + list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
> > + cpufreq_dev_count++;
> > +
> > + /*Verify that all the clip cpus have same freq_min, freq_max
> > limit*/
> > + for_each_cpu(i, clip_cpus) {
> > + /*continue if cpufreq policy not found and not return
> > error*/
> > + if (!cpufreq_get_policy(&policy, i))
> > + continue;
> > + if (min == 0 && max == 0) {
> > + min = policy.cpuinfo.min_freq;
> > + max = policy.cpuinfo.max_freq;
> > + } else {
> > + if (min != policy.cpuinfo.min_freq ||
> > + max != policy.cpuinfo.max_freq)
> > + return ERR_PTR(-EINVAL);
> > +}
> > + }
> > + cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
> > + GFP_KERNEL);
> > + if (!cpufreq_dev)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
> > +
> > + if (cpufreq_dev_count == 0)
> > + mutex_init(&cooling_cpufreq_lock);
> > +
> > + ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
> > + if (ret) {
> > + kfree(cpufreq_dev);
> > + return ERR_PTR(-EINVAL);
> > + }
> > +
> > + sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
> > +
> > + cool_dev = thermal_cooling_device_register(dev_name,
> > cpufreq_dev,
> > + &cpufreq_cooling_ops);
> > + if (!cool_dev) {
> > + release_idr(&cpufreq_idr, cpufreq_dev->id);
> > + kfree(cpufreq_dev);
> > + return ERR_PTR(-EINVAL);
> > + }
> > + cpufreq_dev->id = id;
> > + cpufreq_dev->cool_dev = cool_dev;
> > + cpufreq_dev->cpufreq_state = 0;
> > + mutex_lock(&cooling_cpufreq_lock);
> > + list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
> > +
> > + /* Register the notifier for first cpufreq cooling device */
> > + if (cpufreq_dev_count == 0)
> > +
> > cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
> > +
> > CPUFREQ_POLICY_NOTIFIER);
> > +
> > + mutex_unlock(&cooling_cpufreq_lock);
> > + return cool_dev;
> > +}
> > +EXPORT_SYMBOL(cpufreq_cooling_register);
> > +
> > +/**
> > + * cpufreq_cooling_unregister - function to remove cpufreq cooling
> > device.
> > + * @cdev: thermal cooling device pointer.
> > + */
> > +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> > +{
> > + struct cpufreq_cooling_device *cpufreq_dev = NULL;
> > + unsigned int cpufreq_dev_count = 0;
> > +
> > + mutex_lock(&cooling_cpufreq_lock);
> > + list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
> > + if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
> > + break;
> > + cpufreq_dev_count++;
> > + }
> > +
> > + if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
> > + mutex_unlock(&cooling_cpufreq_lock);
> > + return;
> > + }
> > +
> > + list_del(&cpufreq_dev->node);
> > +
> > + /* Unregister the notifier for the last cpufreq cooling device
> > */
> > + if (cpufreq_dev_count == 1) {
> > +
> > cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> > + CPUFREQ_POLICY_NOTIFIER);
> > + }
> > + mutex_unlock(&cooling_cpufreq_lock);
> > + thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
> > + release_idr(&cpufreq_idr, cpufreq_dev->id);
> > + if (cpufreq_dev_count == 1)
> > + mutex_destroy(&cooling_cpufreq_lock);
> > + kfree(cpufreq_dev);
> > +}
> > +EXPORT_SYMBOL(cpufreq_cooling_unregister);
> > diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> > new file mode 100644
> > index 0000000..555b917
> > --- /dev/null
> > +++ b/include/linux/cpu_cooling.h
> > @@ -0,0 +1,79 @@
> > +/*
> > + * 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
> > +
> > +/**
> > + * cputherm_register_notifier - Register a notifier with cpu cooling
> > interface.
> > + * @nb: struct notifier_block * with callback info.
> > + * @list: integer value for which notification is needed. possible
> > values are
> > + * CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> > + *
> > + * This exported function registers a driver with cpu cooling layer.
> > The driver
> > + * will be notified when any cpu cooling action is called.
> > + */
> > +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> > list);
> > +
> > +/**
> > + * cputherm_unregister_notifier - Un-register a notifier.
> > + * @nb: struct notifier_block * with callback info.
> > + * @list: integer value for which notification is needed. values
> > possible are
> > + * CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> > + *
> > + * This exported function un-registers a driver with cpu cooling layer.
> > + */
> > +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned
> > int list);
> > +
> > +#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__ */
> > --
> > 1.7.1
> >
>
>
>
> --
>
> Eduardo Valentin