Re: [linux-pm] [RESEND PATCH v4 1/5] thermal: add generic cpufreqcooling implementation

[amit kachhap]

On Thu, Jul 12, 2012 at 8:40 PM, Valentin, Eduardo
<eduardo.valentin@xxxxxx> wrote:
> Amit,
>
> On Thu, Jul 12, 2012 at 4:41 PM, Amit Daniel Kachhap
> <amit.kachhap@xxxxxxxxxx> 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.
>>  * TI OMAP (git://git.linaro.org/people/amitdanielk/linux.git omap4460_thermal)
>
> FYI, I have rewriten the OMAP BG driver and currently trying to push
> it to staging area. It should now support more omap versions. I will
> readapt the cpu cooling based on this patch.
>
> I am keeping the reworked driver here:
> git@xxxxxxxxxxxxx:thermal-framework/thermal-framework.git
> thermal_work/omap/bandgap_staging
>

Yes Eduardo, The link I have given here is slightly old. After your
implementation is done maybe this link can be updated.

Thanks,
Amit D
>>  * 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 OMAP and 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 codes 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 freq_clip_table *tab_ptr, unsigned int tab_size)
>>    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@xxxxxxxxxxxxxxxxxxxx: fix comment layout]
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxxxxx>
>> Cc: Donggeun Kim <dg77.kim@xxxxxxxxxxx>
>> Cc: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
>> Cc: SangWook Ju <sw.ju@xxxxxxxxxxx>
>> Cc: Durgadoss <durgadoss.r@xxxxxxxxx>
>> Cc: Len Brown <lenb@xxxxxxxxxx>
>> Cc: Jean Delvare <khali@xxxxxxxxxxxx>
>> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> ---
>>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>>  drivers/thermal/Kconfig                   |   11 +
>>  drivers/thermal/Makefile                  |    3 +-
>>  drivers/thermal/cpu_cooling.c             |  483 +++++++++++++++++++++++++++++
>>  include/linux/cpu_cooling.h               |   99 ++++++
>>  5 files changed, 655 insertions(+), 1 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..557adb8
>> --- /dev/null
>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>> @@ -0,0 +1,60 @@
>> +CPU cooling APIs How To
>> +===================================
>> +
>> +Written by Amit Daniel Kachhap <amit.kachhap@xxxxxxxxxx>
>> +
>> +Updated: 12 May 2012
>> +
>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> +
>> +0. Introduction
>> +
>> +The generic cpu cooling(freq clipping, cpuhotplug etc) 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 freq_clip_table *tab_ptr, unsigned int tab_size)
>> +
>> +    This interface function registers the cpufreq cooling device with the name
>> +    "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
>> +    cooling devices.
>> +
>> +    tab_ptr: The table containing the maximum value of frequency to be clipped
>> +    for each cooling state.
>> +       .freq_clip_max: Value of frequency to be clipped for each allowed
>> +        cpus.
>> +       .temp_level: Temperature level at which the frequency clamping will
>> +       happen.
>> +       .mask_val: cpumask of the allowed cpu's
>> +    tab_size: the total number of cpufreq cooling states.
>> +
>> +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 514a691..d9c529f 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 or M here.
>> +
>>  config SPEAR_THERMAL
>>         bool "SPEAr thermal sensor driver"
>>         depends on THERMAL
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index a9fff0b..30c456c 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -3,4 +3,5 @@
>>  #
>>
>>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
>> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> \ No newline at end of file
>> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
>> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> new file mode 100644
>> index 0000000..7a0697f
>> --- /dev/null
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -0,0 +1,483 @@
>> +/*
>> + *  linux/drivers/thermal/cpu_cooling.c
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@xxxxxxxxxx>
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  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.
>> + * @tab_ptr: freq_clip_table table containing the maximum value of frequency to
>> + *     be set for different cooling state.
>> + * @tab_size: integer value representing a count of the above table.
>> + * @cpufreq_state: integer value representing the current state of cpufreq
>> + *     cooling devices.
>> + * @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;
>> +       struct freq_clip_table *tab_ptr;
>> +       unsigned int tab_size;
>> +       unsigned int cpufreq_state;
>> +       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);
>> +
>> +/* per cpu variable to store the previous max frequency allowed */
>> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
>> +
>> +/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
>> +#define NOTIFY_INVALID NULL
>> +static struct freq_clip_table *notify_table;
>> +
>> +/* 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);
>> +}
>> +
>> +/**
>> + * 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, state;
>> +       struct freq_clip_table *th_table, *table_ptr;
>> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>> +       struct cpufreq_cooling_device *cpufreq_ptr;
>> +
>> +       if (cooling_state > cpufreq_device->tab_size)
>> +               return -EINVAL;
>> +
>> +       /* Check if the old cooling action is same as new cooling action */
>> +       if (cpufreq_device->cpufreq_state == cooling_state)
>> +               return 0;
>> +
>> +       /* pass cooling table info to the cpufreq_thermal_notifier callback */
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       if (cooling_state > 0) {
>> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
>> +               notify_table = th_table;
>> +       }
>> +
>> +       /* check if any lower clip frequency active in other cpufreq_device's */
>> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
>> +
>> +               state = cpufreq_ptr->cpufreq_state;
>> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
>> +                       continue;
>> +
>> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
>> +                               &cpufreq_device->allowed_cpus))
>> +                       continue;
>> +
>> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
>> +               if (notify_table == NULL ||
>> +                               (table_ptr->freq_clip_max <
>> +                               notify_table->freq_clip_max))
>> +                       notify_table =  table_ptr;
>> +       }
>> +
>> +       cpufreq_device->cpufreq_state = cooling_state;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               event = CPUFREQ_COOLING_START;
>> +               maskPtr = notify_table->mask_val;
>> +       } else {
>> +               event = CPUFREQ_COOLING_STOP;
>> +       }
>> +
>> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
>> +                                               event, notify_table);
>> +
>> +       for_each_cpu(cpuid, maskPtr) {
>> +               if (is_cpufreq_valid(cpuid))
>> +                       cpufreq_update_policy(cpuid);
>> +       }
>> +
>> +       notify_table = 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)
>> +               return 0;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               max_freq = notify_table->freq_clip_max;
>> +
>> +               if (!per_cpu(max_policy_freq, policy->cpu))
>> +                       per_cpu(max_policy_freq, policy->cpu) = policy->max;
>> +       } else {
>> +               if (per_cpu(max_policy_freq, policy->cpu)) {
>> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
>> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
>> +               } else {
>> +                       max_freq = policy->max;
>> +               }
>> +       }
>> +
>> +       /* 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;
>> +       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->tab_size;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       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.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +{
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       struct freq_clip_table *clip_tab;
>> +       unsigned int cpufreq_dev_count = 0;
>> +       char dev_name[THERMAL_NAME_LENGTH];
>> +       int ret = 0, id = 0, i;
>> +
>> +       if (tab_ptr == NULL || tab_size == 0)
>> +               return ERR_PTR(-EINVAL);
>> +
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>> +               cpufreq_dev_count++;
>> +
>> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
>> +                       GFP_KERNEL);
>> +       if (!cpufreq_dev)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       /* Verify that all the entries of freq_clip_table are present */
>> +       for (i = 0; i < tab_size; i++) {
>> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
>> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
>> +                                       || !clip_tab->temp_level) {
>> +                       kfree(cpufreq_dev);
>> +                       return ERR_PTR(-EINVAL);
>> +               }
>> +               /*
>> +                * Consolidate all the cpumask for all the individual entries
>> +                * of the trip table. This is useful in resetting all the
>> +                * clipped frequencies to the normal level for each cpufreq
>> +                * cooling device.
>> +                */
>> +               cpumask_or(&cpufreq_dev->allowed_cpus,
>> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
>> +       }
>> +
>> +       cpufreq_dev->tab_ptr = tab_ptr;
>> +       cpufreq_dev->tab_size = tab_size;
>> +
>> +       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;
>> +       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);
>> +       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..5a1299f
>> --- /dev/null
>> +++ b/include/linux/cpu_cooling.h
>> @@ -0,0 +1,99 @@
>> +/*
>> + *  linux/include/linux/cpu_cooling.h
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@xxxxxxxxxx>
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  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
>> +
>> +/**
>> + * struct freq_clip_table
>> + * @freq_clip_max: maximum frequency allowed for this cooling state.
>> + * @temp_level: Temperature level at which the temperature clipping will
>> + *     happen.
>> + * @mask_val: cpumask of the allowed cpu's where the clipping will take place.
>> + *
>> + * This structure is required to be filled and passed to the
>> + * cpufreq_cooling_unregister function.
>> + */
>> +struct freq_clip_table {
>> +       unsigned int freq_clip_max;
>> +       unsigned int temp_level;
>> +       const struct cpumask *mask_val;
>> +};
>> +
>> +/**
>> + * 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_FREQ
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + * @mask_val: cpumask containing the allowed cpu's where frequency clipping can
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +
>> +/**
>> + * 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_FREQ */
>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +{
>> +       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
>>
>
>
>
> --
>
> Eduardo Valentin
> --
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