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

["Javi Merino" <javi.merino@arm.com>]

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@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.

>   * @type:	the thermal cooling device type.
>   * @devdata:	device private data.
>   * @ops:		standard thermal cooling devices callbacks.

Cheers,
Javi