[PATCH v1 3/6] thermal: thermal-core: Add notifications support for the cooling states

[Amit Kachhap]

On 5/29/14, Javi Merino <javi.merino at arm.com> wrote:
> Hi Amit,
>
> On Thu, May 29, 2014 at 09:15:31AM +0100, Amit Daniel Kachhap wrote:
>> This patch adds notification infrastructure for any requests related to
>> cooling
>> states. The notifier structure passed is of both Get/Set type. So the
>> receiver
>> of these can sense the new/cur/max cooling state as decided by thermal
>> governor.
>> In addition to that it can also override the cooling state and may do
>> something
>> interesting after receiving these CPU cooling events such as masking some
>> states, enabling some extra conditional states or perform any extra
>> operation
>> for aggressive thermal cooling.
>> The notfications events can be of type,
>>
>> 1. COOLING_SET_STATE_PRE
>> 2. COOLING_SET_STATE_POST
>> 3. COOLING_GET_CUR_STATE
>> 4. COOLING_GET_MAX_STATE
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.daniel at samsung.com>
>> ---
>>  Documentation/thermal/sysfs-api.txt |   21 +++++++++++
>>  drivers/thermal/thermal_core.c      |   69
>> ++++++++++++++++++++++++++++++++++-
>>  include/linux/thermal.h             |   21 +++++++++++
>>  3 files changed, 109 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/thermal/sysfs-api.txt
>> b/Documentation/thermal/sysfs-api.txt
>> index 87519cb..5f45e03 100644
>> --- a/Documentation/thermal/sysfs-api.txt
>> +++ b/Documentation/thermal/sysfs-api.txt
>> @@ -92,6 +92,27 @@ temperature) and throttle appropriate devices.
>>      It deletes the corresponding entry form /sys/class/thermal folder
>> and
>>      unbind itself from all the thermal zone devices using it.
>>
>> +1.2.3 int thermal_cooling_register_notifier(struct notifier_block *nb)
>> +
>> +    This interface function registers the client notifier handler. The
>> notifier
>> +    handler can use this to monitor or update any cooling state
>> requests.
>> +    nb: notifier structure containing client notifier handler.
>> +
>> +1.2.4 int thermal_cooling_unregister_notifier(struct notifier_block *nb)
>> +
>> +    This interface function unregisters the client notifier handler.
>> +    nb: notifier structure containing client notifier handler.
>> +
>> +1.2.5 int thermal_cooling_notify_states(struct thermal_cooling_status
>> *request,enum cooling_state_ops op)
>> +
>> +    This interface function invokes the earlier registered cooling states
>> handler.
>> +    request: holds the relevant cooling state value.
>> +	.cur_state: current cooling state.
>> +	.new_state: new cooling state to be set.
>> +	.max_state: max cooling state.
>> +	.devdata: driver private data pointer.
>> +    op: describes various operation supported.
>> +
>>  1.3 interface for binding a thermal zone device with a thermal cooling
>> device
>>  1.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device
>> *tz,
>>  	int trip, struct thermal_cooling_device *cdev,
>> diff --git a/drivers/thermal/thermal_core.c
>> b/drivers/thermal/thermal_core.c
>> index 71b0ec0..1a60f83 100644
>> --- a/drivers/thermal/thermal_core.c
>> +++ b/drivers/thermal/thermal_core.c
>> @@ -52,6 +52,8 @@ static DEFINE_MUTEX(thermal_idr_lock);
>>  static LIST_HEAD(thermal_tz_list);
>>  static LIST_HEAD(thermal_cdev_list);
>>  static LIST_HEAD(thermal_governor_list);
>> +/* Notfier list to validates/updates the cpufreq cooling states */
>> +static BLOCKING_NOTIFIER_HEAD(cooling_state_notifier_list);
>>
>>  static DEFINE_MUTEX(thermal_list_lock);
>>  static DEFINE_MUTEX(thermal_governor_lock);
>> @@ -1073,8 +1075,71 @@ static struct class thermal_class = {
>>  };
>>
>>  /**
>> - * __thermal_cooling_device_register() - register a new thermal cooling
>> device
>> - * @np:		a pointer to a device tree node.
>> + * thermal_cooling_notify_states - Invoke the necessary cooling states
>> handler.
>> + * @request: holds the relevant cooling state value. say if the cooling
>> state
>> + * operation is of type COOLING_GET_MAX_STATE, then request holds
>> + * the current max cooling state value.
>> + * @op: different operations supported
>> + *
>> + * This API allows the registered user to recieve the different cooling
>> + * notifications like current state, max state and set state.
>> + *
>> + * Return: 0 (success)
>> + */
>> +int thermal_cooling_notify_states(struct thermal_cooling_status
>> *request,
>> +				enum cooling_state_ops op)
>> +{
>> +	/* Invoke the notifiers which have registered for this state change */
>> +	if (op == COOLING_SET_STATE_PRE ||
>> +		op == COOLING_SET_STATE_POST ||
>> +		op == COOLING_GET_MAX_STATE ||
>> +		op == COOLING_GET_CUR_STATE) {
>> +		blocking_notifier_call_chain(
>> +			&cooling_state_notifier_list, op, request);
>> +	}
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_cooling_notify_states);
>> +
>> +/**
>> + * thermal_cooling_register_notifier - registers a notifier with thermal
>> cooling.
>> + * @nb:	notifier function to register.
>> + *
>> + * Add a driver to receive all cooling notifications like current state,
>> + * max state and set state. The drivers after reading the events can
>> perform
>> + * some mapping like grouping some P states into 1 cooling state.
>> + *
>> + * Return: 0 (success)
>> + */
>> +int thermal_cooling_register_notifier(struct notifier_block *nb)
>> +{
>> +	int ret = 0;
>> +	ret = blocking_notifier_chain_register(
>> +				&cooling_state_notifier_list, nb);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_cooling_register_notifier);
>> +
>> +/**
>> + * thermal_cooling_unregister_notifier - unregisters a notifier with
>> thermal
>> + * cooling.
>> + * @nb:	notifier function to unregister.
>> + *
>> + * Removes a driver to receive further cooling notifications.
>> + *
>> + * Return: 0 (success)
>
> Or %-ENOENT if the notifier is not registered.
>
>> + */
>> +int thermal_cooling_unregister_notifier(struct notifier_block *nb)
>> +{
>> +	int ret = 0;
>> +	ret = blocking_notifier_chain_unregister(
>> +				&cooling_state_notifier_list, nb);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_cooling_unregister_notifier);
>> +
>> +/**
>> + * thermal_cooling_device_register() - register a new thermal cooling
>> device
>
> This is wrong, the function below this comment is still
> __thermal_cooling_device_register() whose first parameter is np, not
> type.
I did not add this. This seems wrong. Will modify this as a fix in the version.

Thanks,
Amit
>
>>   * @type:	the thermal cooling device type.
>>   * @devdata:	device private data.
>>   * @ops:		standard thermal cooling devices callbacks.
>
> Cheers,
> Javi
>
>