Re: [PATCH v4 1/5] thermal: Add generic cpufreq cooling implementation

[amit kachhap]

Hi Rob/Eduardo,

As these patches have still not made into mainline. I will rebase the
whole set along with your suggestion and send them shortly.
Sorry for late reply.

Thanks,
Amit Daniel

On Tue, Jun 26, 2012 at 1:12 PM, Valentin, Eduardo
<eduardo.valentin@xxxxxx> wrote:
> Hey Rob and Amit,
>
> On Tue, Jun 26, 2012 at 6:12 AM, Rob Lee <rob.lee@xxxxxxxxxx> wrote:
>> Hey Amit,
>>
>> I was just re-organizing the imx thermal driver that uses this cpu
>> cooling interface and noticed a couple of small issues here.   If
>
> While rewriting the OMAP BG driver on top of this series I noticed
> similar issues. Apart from those pointed by Rob, I have another minor
> fix.
>
>> these suggestions are agreed upon and if it's too late for these
>> issues be changed with this patchset, I can submit them separately
>> unless you'd prefer to.
>>
>> On Sat, May 12, 2012 at 4:40 AM, Amit Daniel Kachhap
>> <amit.kachhap@xxxxxxxxxx> wrote:
>>> This patch adds 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.
>>>
>>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxxxxx>
>>> ---
>>>  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
>>
>> Perhaps the name CPU_COOLING or CPUFREQ_COOLING would more accurately
>> describe this functionality?  I like the latter since now this
>> mechanism only supports cooling by using cpufreq.
>>
>>> +       bool "generic cpu cooling support"
>>
>> If we use CPUFREQ_COOLING, then perhaps this could say:
>>
>> bool "cpu cooling through cpufreq frequency limiting"
>>
>>> +       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.
>>> +
>>
>> Currently, only the "frequency reduction" method exists so perhaps
>> it's best to remove mention of "cpu hotplug and any other ways of
>> reducing temperature"?  Here'as a version for cpufreq only:
>>
>> config CPUFREQ_COOLING
>>        bool "cpu cooling through cpufreq frequency limiting"
>>        depends on THERMAL && CPU_FREQ
>>        help
>>          This implements a generic cpu cooling mechanism through cpufreq
>>          frequency limiting. 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..c40d9a0
>>> --- /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 codes 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..ed6c096
>>> --- /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_TYPE and CPUHOTPLUG_COOLING_TYPE.
>>
>> CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE should be changed to
>> CPUFREQ_COOLING_START CPUFREQ_COOLING_STOP, right?
>>
>>> + *
>>> + * 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_TYPE.
>>
>> Should be changed to CPUFREQ_COOLING_START, CPUFREQ_COOLING_STOP, right?
>>
>>> + *
>>> + * 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
>>
>> Consider changing this to "#ifdef CPU_THERMAL"  A platform thermal
>> driver may want to always call this function as its cpu cooling
>> mechanism but it should still function without the cpu_cooling being
>> enabled.  In this case, the platform thermal driver would only provide
>> temperature readings and critical trip point handling.  But if the
>> platform happened may have CONFIG_CPU_FREQ enabled, a build error
>> would occur in the current implementation.
>
> I agree here. It makes more sense to have the check against CPU_THERMAL
>
>>
>> (the CONFIG_CPU_FREQ requirement will be met by CPU_THERMAL being
>> enabled since it also implies CONFIG_CPU_FREQ being enabled per the
>> Kconfig dependency)
>
> True.
>
>>
>>> +/**
>>> + * 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*/
>>
>> Modify comment if above suggestion is taken.
>>
>>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>
> The above semicollon will cause a build error in case this path of the
> ifdef is taken.
>
>>> +{
>>> +       return NULL;
>>> +}
>>> +static inline void cpufreq_cooling_unregister(
>>> +               struct thermal_cooling_device *cdev)
>>> +{
>>> +       return;
>>> +}
>>> +#endif /*CONFIG_CPU_FREQ*/
>>
>> Modify comment if above suggestion is taken.
>>
>>> +
>>> +#endif /* __CPU_COOLING_H__ */
>>> --
>>> 1.7.1
>>>
>>>
>>> _______________________________________________
>>> linaro-dev mailing list
>>> linaro-dev@xxxxxxxxxxxxxxxx
>>> http://lists.linaro.org/mailman/listinfo/linaro-dev
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>
>
>
> --
>
> Eduardo Valentin
> --
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