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    SubjectRe: [PATCH 2/4] thermal: Add generic cpufreq cooling implementation
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    Hi Durgadoss,

    Thanks for the detailed review comments.

    On 24 February 2012 16:34, R, Durgadoss <durgadoss.r@intel.com> wrote:
    > Hi Amit,
    >
    >> -----Original Message-----
    >> From: amit kachhap [mailto:amitdanielk@gmail.com] On Behalf Of Amit Daniel
    >> Kachhap
    >> Sent: Wednesday, February 22, 2012 3:44 PM
    >> To: linux-pm@lists.linux-foundation.org
    >> Cc: linux-kernel@vger.kernel.org; mjg59@srcf.ucam.org; linux-
    >> acpi@vger.kernel.org; lenb@kernel.org; linaro-dev@lists.linaro.org;
    >> amit.kachhap@linaro.org; R, Durgadoss; rob.lee@linaro.org; patches@linaro.org
    >> Subject: [PATCH 2/4] thermal: Add generic cpufreq cooling implementation
    >>
    >> This patch adds support for generic cpu thermal cooling low level
    >> implementations using frequency scaling up/down based on the request
    >> from user. Different cpu related cooling devices can be registered by the
    >
    > I believe what you mean by 'user' is another Driver using this code.. right ??
    Yes.
    >
    >> user and the binding of these cooling devices to the corresponding
    >> trip points can be easily done as the registration API's return the
    >> cooling device pointer. The user of these api's are responsible for
    >> passing clipping frequency in percentages.
    >>
    >> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
    >> ---
    >>  Documentation/thermal/cpu-cooling-api.txt |   40 ++++
    >>  drivers/thermal/Kconfig                   |   11 +
    >>  drivers/thermal/Makefile                  |    1 +
    >>  drivers/thermal/cpu_cooling.c             |  310 +++++++++++++++++++++++++++++
    >>  include/linux/cpu_cooling.h               |   54 +++++
    >>  5 files changed, 416 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..04de67c
    >> --- /dev/null
    >> +++ b/Documentation/thermal/cpu-cooling-api.txt
    >> @@ -0,0 +1,40 @@
    >> +CPU cooling api's How To
    >> +===================================
    >> +
    >> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
    >> +
    >> +Updated: 13 Dec 2011
    >> +
    >> +Copyright (c)  2011 Samsung Electronics Co., Ltd(http://www.samsung.com)
    >> +
    >> +0. Introduction
    >> +
    >> +The generic cpu cooling(freq clipping, cpuhotplug) provides
    >> +registration/unregistration api's to the user. The binding of the cooling
    >> +devices to the trip point is left for the user. The registration api's returns
    >> +the cooling device pointer.
    >> +
    >> +1. cpufreq cooling api's
    >> +
    >> +1.1 cpufreq registration api's
    >> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
    >> +     struct freq_pctg_table *tab_ptr, unsigned int tab_size,
    >> +     const struct cpumask *mask_val)
    >> +
    >> +    This interface function registers the cpufreq cooling device with the name
    >> +    "thermal-cpufreq-%x". This api can support multiple instance of cpufreq
    >> cooling
    >> +    devices.
    >> +
    >> +    tab_ptr: The table containing the percentage of frequency to be clipped
    >> for
    >> +    each cooling state.
    >> +     .freq_clip_pctg: Percentage of frequency to be clipped for each allowed
    >> +      cpus.
    >> +     .polling_interval: polling interval for this cooling state.
    >> +    tab_size: the total number of cooling state.
    >
    > Although I can understand that the table size is equal to
    > the total number of cooling states, it is better to name it 'num_cooling_states'
    > (or something) that means what it is..
    Yes your idea makes more sense. Will accept it in the next version.
    >
    >> +    mask_val: all the allowed cpu's where frequency clipping can 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.
    >> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
    >> index f7f71b2..298c1cd 100644
    >> --- a/drivers/thermal/Kconfig
    >> +++ b/drivers/thermal/Kconfig
    >> @@ -18,3 +18,14 @@ config THERMAL_HWMON
    >>       depends on THERMAL
    >>       depends on HWMON=y || HWMON=THERMAL
    >>       default y
    >> +
    >> +config CPU_THERMAL
    >> +     bool "generic cpu cooling support"
    >> +     depends on THERMAL
    >> +     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 or M here.
    >> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
    >> index 31108a0..655cbc4 100644
    >> --- a/drivers/thermal/Makefile
    >> +++ b/drivers/thermal/Makefile
    >> @@ -3,3 +3,4 @@
    >>  #
    >>
    >>  obj-$(CONFIG_THERMAL)                += thermal_sys.o
    >> +obj-$(CONFIG_CPU_THERMAL)    += cpu_cooling.o
    >> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
    >> new file mode 100644
    >> index 0000000..298f550
    >> --- /dev/null
    >> +++ b/drivers/thermal/cpu_cooling.c
    >> @@ -0,0 +1,310 @@
    >> +/*
    >> + *  linux/drivers/thermal/cpu_cooling.c
    >> + *
    >> + *  Copyright (C) 2011       Samsung Electronics Co., Ltd(http://www.samsung.com)
    >> + *  Copyright (C) 2011  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>
    >> +
    >> +#ifdef CONFIG_CPU_FREQ
    >
    > Except the _idr methods, all the code is inside this #ifdef.
    > So, I think it is better to add this dependency in Kconfig,
    > and leave this code clean w/o many #ifdef's.
    ok
    >
    >> +struct cpufreq_cooling_device {
    >> +     int id;
    >> +     struct thermal_cooling_device *cool_dev;
    >> +     struct freq_pctg_table *tab_ptr;
    >> +     unsigned int tab_size;
    >> +     unsigned int cpufreq_state;
    >> +     const struct cpumask *allowed_cpus;
    >> +     struct list_head node;
    >> +};
    >> +
    >> +static LIST_HEAD(cooling_cpufreq_list);
    >> +static DEFINE_MUTEX(cooling_cpufreq_lock);
    >> +static DEFINE_IDR(cpufreq_idr);
    >> +static struct cpufreq_cooling_device *notify_cpufreq;
    >
    > Please move this after the DEFINE_PER_CPU.
    > Hard to notice here..
    ok
    >
    >> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
    >> +#endif /*CONFIG_CPU_FREQ*/
    >> +
    >> +static int get_idr(struct idr *idr, struct mutex *lock, int *id)
    >> +{
    >> +     int err;
    >> +again:
    >> +     if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
    >> +             return -ENOMEM;
    >> +
    >> +     if (lock)
    >> +             mutex_lock(lock);
    >> +     err = idr_get_new(idr, NULL, id);
    >> +     if (lock)
    >> +             mutex_unlock(lock);
    >> +     if (unlikely(err == -EAGAIN))
    >> +             goto again;
    >> +     else if (unlikely(err))
    >> +             return err;
    >> +
    >> +     *id = *id & MAX_ID_MASK;
    >> +     return 0;
    >> +}
    >> +
    >> +static void release_idr(struct idr *idr, struct mutex *lock, int id)
    >> +{
    >> +     if (lock)
    >> +             mutex_lock(lock);
    >> +     idr_remove(idr, id);
    >> +     if (lock)
    >> +             mutex_unlock(lock);
    >> +}
    >> +
    >> +#ifdef CONFIG_CPU_FREQ
    >> +/*Below codes defines functions to be used for cpufreq as cooling device*/
    >> +static bool is_cpufreq_valid(int cpu)
    >> +{
    >> +     struct cpufreq_policy policy;
    >> +     if (!cpufreq_get_policy(&policy, cpu))
    >> +             return true;
    >> +     return false;
    >
    > Why not just do a return !cpufreq_get_policy(&policy, cpu);
    ok
    >
    >> +}
    >> +
    >> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
    >> *cpufreq_device,
    >> +                             unsigned long cooling_state)
    >> +{
    >> +     int cpuid, this_cpu = smp_processor_id();
    >> +
    >> +     if (!is_cpufreq_valid(this_cpu))
    >
    > You are not using this_cpu anywhere else..so, directly use
    > Smp_processor_id() here..
    >
    Ok agreed.
    >> +             return 0;
    >> +
    >> +     if (cooling_state > cpufreq_device->tab_size)
    >> +             return -EINVAL;
    >> +
    >> +     /*Check if last cooling level is same as current cooling level*/
    >
    > Use either 'state' or 'level' in comments as well as the variable name
    > Makes it easy to read..

    Ok, will use state.
    >
    >> +     if (cpufreq_device->cpufreq_state == cooling_state)
    >> +             return 0;
    >> +
    >> +     cpufreq_device->cpufreq_state = cooling_state;
    >> +
    >> +     /*cpufreq thermal notifier uses this cpufreq device pointer*/
    >> +     notify_cpufreq = cpufreq_device;
    >> +
    >> +     for_each_cpu(cpuid, cpufreq_device->allowed_cpus) {
    >> +             if (is_cpufreq_valid(cpuid))
    >> +                     cpufreq_update_policy(cpuid);
    >> +     }
    >> +
    >> +     return 0;
    >> +}
    >> +
    >> +static int thermal_cpufreq_notifier(struct notifier_block *nb,
    >> +                                     unsigned long event, void *data)
    >> +{
    >> +     struct cpufreq_policy *policy = data;
    >> +     struct freq_pctg_table *th_table;
    >> +     unsigned long max_freq = 0;
    >> +     unsigned int th_pctg = 0, level;
    >> +
    >> +     if (event != CPUFREQ_ADJUST)
    >> +             return 0;
    >> +
    >> +     if (!notify_cpufreq)
    >> +             return 0;
    >
    > Why not combine both if's with an || ?
    Ok
    >
    >> +
    >> +     level = notify_cpufreq->cpufreq_state;
    >
    > Yes..here it is..please use level/state..
    Ok, will use state
    >
    >> +
    >> +     if (level > 0) {
    >> +             th_table =
    >> +                     &(notify_cpufreq->tab_ptr[level - 1]);
    >> +             th_pctg = th_table->freq_clip_pctg;
    >> +             max_freq =
    >> +             (policy->cpuinfo.max_freq * (100 - th_pctg)) / 100;
    >> +
    >> +             if (per_cpu(max_policy_freq, policy->cpu) == 0)
    >> +                     per_cpu(max_policy_freq, policy->cpu) = policy->max;
    >> +     } else {
    >> +             if (per_cpu(max_policy_freq, policy->cpu) != 0) {
    >> +                     max_freq = per_cpu(max_policy_freq, policy->cpu);
    >> +                     per_cpu(max_policy_freq, policy->cpu) = 0;
    >> +             } else {
    >> +                     max_freq = policy->max;
    >> +             }
    >> +     }
    >> +
    >> +     cpufreq_verify_within_limits(policy, 0, max_freq);
    >> +
    >> +     return 0;
    >> +}
    >> +
    >> +/*
    >> + * cpufreq cooling device callback functions
    >> + */
    >> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
    >> +                              unsigned long *state)
    >> +{
    >> +     struct cpufreq_cooling_device *cpufreq_device = NULL;
    >
    > Why assigning NULL ?
    yes it is not needed.
    >
    >> +
    >> +     mutex_lock(&cooling_cpufreq_lock);
    >> +     list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
    >> +             if (cpufreq_device && cpufreq_device->cool_dev == cdev)
    >> +                     break;
    >> +
    >> +     mutex_unlock(&cooling_cpufreq_lock);
    >> +     if (!cpufreq_device || cpufreq_device->cool_dev != cdev)
    >> +             return -EINVAL;
    >> +
    >> +     *state = cpufreq_device->tab_size;
    >> +     return 0;
    >> +}
    >
    > The above can be simplified this way:
    >        int ret = -EINVAL;
    >        mutex_lock(&cooling_cpufreq_lock);
    >        list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
    >                if (cpufreq_device->cool_dev == cdev) {
    >                        *state = cpufreq_device->tab_size;
    >                        ret = 0;
    >                        break;
    >                }
    >
    >        mutex_unlock(&cooling_cpufreq_lock);
    >        return ret;
    >
    > I think the same can be done for the get_ function below..and similar ones
    > in the patch 3/4.

    Ok accepted.
    >
    >> +
    >> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
    >> +                              unsigned long *state)
    >> +{
    >> +     struct cpufreq_cooling_device *cpufreq_device = NULL;
    >> +
    >> +     mutex_lock(&cooling_cpufreq_lock);
    >> +     list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
    >> +             if (cpufreq_device && cpufreq_device->cool_dev == cdev)
    >> +                     break;
    >> +
    >> +     mutex_unlock(&cooling_cpufreq_lock);
    >> +     if (!cpufreq_device || cpufreq_device->cool_dev != cdev)
    >> +             return -EINVAL;
    >> +     *state = cpufreq_device->cpufreq_state;
    >> +     return 0;
    >> +}
    >> +
    >> +/*This cooling may be as PASSIVE/ACTIVE type*/
    >> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
    >> +                              unsigned long state)
    >> +{
    >> +     struct cpufreq_cooling_device *cpufreq_device = NULL;
    >> +
    >> +     mutex_lock(&cooling_cpufreq_lock);
    >> +     list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node)
    >> +             if (cpufreq_device && cpufreq_device->cool_dev == cdev)
    >> +                     break;
    >> +
    >> +     mutex_unlock(&cooling_cpufreq_lock);
    >> +     if (!cpufreq_device || cpufreq_device->cool_dev != cdev)
    >> +             return -EINVAL;
    >> +
    >> +     cpufreq_apply_cooling(cpufreq_device, state);
    >> +     return 0;
    >> +}
    >> +
    >> +/* bind cpufreq callbacks to cpufreq cooling device */
    >> +static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
    >> +     .get_max_state = cpufreq_get_max_state,
    >> +     .get_cur_state = cpufreq_get_cur_state,
    >> +     .set_cur_state = cpufreq_set_cur_state,
    >> +};
    >> +
    >> +static struct notifier_block thermal_cpufreq_notifier_block = {
    >> +     .notifier_call = thermal_cpufreq_notifier,
    >> +};
    >> +
    >> +struct thermal_cooling_device *cpufreq_cooling_register(
    >> +     struct freq_pctg_table *tab_ptr, unsigned int tab_size,
    >> +     const struct cpumask *mask_val)
    >> +{
    >> +     struct thermal_cooling_device *cool_dev;
    >> +     struct cpufreq_cooling_device *cpufreq_dev = NULL;
    >> +     unsigned int count = 0;
    >> +     char dev_name[THERMAL_NAME_LENGTH];
    >> +     int ret = 0, id = 0;
    >> +
    >> +     if (tab_ptr == NULL || tab_size == 0)
    >> +             return ERR_PTR(-EINVAL);
    >> +
    >> +     list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
    >> +             count++;
    >> +
    >> +     cpufreq_dev =
    >> +             kzalloc(sizeof(struct cpufreq_cooling_device), GFP_KERNEL);
    >> +
    >> +     if (!cpufreq_dev)
    >> +             return ERR_PTR(-ENOMEM);
    >> +
    >> +     cpufreq_dev->tab_ptr = tab_ptr;
    >> +     cpufreq_dev->tab_size = tab_size;
    >> +     cpufreq_dev->allowed_cpus = mask_val;
    >> +
    >> +     ret = get_idr(&cpufreq_idr, &cooling_cpufreq_lock, &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, &cooling_cpufreq_lock,
    >> +                                             cpufreq_dev->id);
    >> +             kfree(cpufreq_dev);
    >> +             return ERR_PTR(-EINVAL);
    >> +     }
    >> +     cpufreq_dev->id = id;
    >> +     cpufreq_dev->cool_dev = cool_dev;
    >> +     mutex_lock(&cooling_cpufreq_lock);
    >> +     list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
    >> +     mutex_unlock(&cooling_cpufreq_lock);
    >> +
    >> +     if (count == 0)
    >> +             cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
    >> +                                             CPUFREQ_POLICY_NOTIFIER);
    >
    > Why do we register only when count is 0 ?
    > Or should this be 'if (count > 0)' ?
    Count represents the number of cpufreq type cooling devices. So for
    the first call of this API , cpufreq_register_notifier is called.
    Other call to cpufreq_cooling_register will use the same notifier. May
    be using bool flag instead of count variable is better.
    >
    >> +     return cool_dev;
    >> +}
    >> +EXPORT_SYMBOL(cpufreq_cooling_register);
    >> +
    >> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
    >> +{
    >> +     struct cpufreq_cooling_device *cpufreq_dev = NULL;
    >> +     unsigned int 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;
    >> +             count++;
    >> +     }
    >> +
    >> +     if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
    >> +             mutex_unlock(&cooling_cpufreq_lock);
    >> +             return;
    >> +     }
    >> +
    >> +     list_del(&cpufreq_dev->node);
    >> +     mutex_unlock(&cooling_cpufreq_lock);
    >> +
    >> +     if (count == 1)
    >
    > Same here..I do not get the idea behind this..
    > Shouldn't this be 'if (count > 0)' ?
    Same as above.
    >
    > In general,
    > I would like to see a real driver using these API's. This will help
    > everybody to understand the working of these API's much better.
    Actually RFC version of the driver is already posted which uses these
    api's. (https://lkml.org/lkml/2011/12/21/169). I forgot to add this
    link in this patchset.
    I will post the new version of the driver shortly.
    >
    > Thanks,
    > Durga
    >
    >> +             cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
    >> +                                     CPUFREQ_POLICY_NOTIFIER);
    >> +
    >> +     thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
    >> +     release_idr(&cpufreq_idr, &cooling_cpufreq_lock, cpufreq_dev->id);
    >> +     kfree(cpufreq_dev);
    >> +}
    >> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
    >> +#endif /*CONFIG_CPU_FREQ*/
    >> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
    >> new file mode 100644
    >> index 0000000..5dc5632
    >> --- /dev/null
    >> +++ b/include/linux/cpu_cooling.h
    >> @@ -0,0 +1,54 @@
    >> +/*
    >> + *  linux/include/linux/cpu_cooling.h
    >> + *
    >> + *  Copyright (C) 2011       Samsung Electronics Co., Ltd(http://www.samsung.com)
    >> + *  Copyright (C) 2011  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>
    >> +
    >> +struct freq_pctg_table {
    >> +     unsigned int freq_clip_pctg;
    >> +     unsigned int polling_interval;
    >> +};
    >> +
    >> +#ifdef CONFIG_CPU_FREQ
    >> +struct thermal_cooling_device *cpufreq_cooling_register(
    >> +     struct freq_pctg_table *tab_ptr, unsigned int tab_size,
    >> +     const struct cpumask *mask_val);
    >> +
    >> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
    >> +#else /*!CONFIG_CPU_FREQ*/
    >> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
    >> +     struct freq_pctg_table *tab_ptr, unsigned int tab_size,
    >> +     const struct cpumask *mask_val)
    >> +{
    >> +     return NULL;
    >> +}
    >> +static inline void cpufreq_cooling_unregister(
    >> +                             struct thermal_cooling_device *cdev)
    >> +{
    >> +     return;
    >> +}
    >> +#endif       /*CONFIG_CPU_FREQ*/
    >> +
    >> +#endif /* __CPU_COOLING_H__ */
    >> --
    >> 1.7.1
    >
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