Re: [RFC 2/4] power: core: Add generic interface to get battery specification.

[Oliver Neukum <oneukum@suse.de>]

On Fri, 2015-03-06 at 16:03 +0530, Jenny TC wrote:
> In power supply system, battery specification's dealt as static
> information regardless of battery chainging. And it often assumed
> fuelgauge's role to hold battery specification even same driver is
> used with different batteries. To make subsystem handles above cases
> properly, this patch adds helper functions to manager the battery
> specification.
> 
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
> Signed-off-by: Jenny TC <jenny.tc@intel.com>
> ---
>  drivers/power/power_supply_core.c |   86 +++++++++++++++++++++++++++++++++++++
>  include/linux/power_supply.h      |   12 ++++++
>  2 files changed, 98 insertions(+)
> 
> diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
> index 694e8cd..99c3455 100644
> --- a/drivers/power/power_supply_core.c
> +++ b/drivers/power/power_supply_core.c
> @@ -650,6 +650,92 @@ static void __exit power_supply_class_exit(void)
>  subsys_initcall(power_supply_class_init);
>  module_exit(power_supply_class_exit);
>  
> +/****************************************************************
> + *                   Battery information interface              *
> + ****************************************************************/
> +
> +ATOMIC_NOTIFIER_HEAD(psy_battery_info_notifier);
> +static LIST_HEAD(psy_battery_info_list);
> +
> +struct psy_battery_info {
> +	struct list_head entry;
> +	struct psy_charging_obj *info;
> +};
> +
> +int psy_battery_info_notifier_register(struct notifier_block *nb)
> +{
> +	return atomic_notifier_chain_register(&psy_battery_info_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(psy_battery_info_notifier_register);
> +
> +void psy_battery_info_notifier_unregister(struct notifier_block *nb)
> +{
> +	atomic_notifier_chain_unregister(&psy_battery_info_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(psy_battery_info_notifier_unregister);
> +
> +struct psy_charging_obj *psy_get_battery_info(const char *name)
> +{
> +	struct psy_battery_info *battery;
> +
> +	/* Sanity check */
> +	if (!name)
> +		goto err_out;
> +
> +	list_for_each_entry(battery, &psy_battery_info_list, entry) {
> +		if (!strcmp(battery->info->name, name))
> +			return battery->info;
> +	}
> +
> +err_out:
> +	return NULL;
> +}
> +EXPORT_SYMBOL(psy_get_battery_info);
> +
> +int psy_register_battery_info(struct psy_charging_obj *info)
> +{
> +	struct psy_battery_info *battery;
> +
> +	/* Sanity check */
> +	if (!info->name)
> +		return -EINVAL;
> +
> +	/* Check if same data is existed */
> +	list_for_each_entry(battery, &psy_battery_info_list, entry)
> +		if (!strcmp(battery->info->name, info->name))
> +			return -EEXIST;
> +
> +	battery = kzalloc(sizeof(*battery), GFP_KERNEL);

That is a race condition. If you check for duplication, you'll
need a lock.

> +	if (!battery)
> +		return -ENOMEM;
> +
> +	battery->info = info;
> +	list_add_tail(&battery->entry, &psy_battery_info_list);
> +
> +	atomic_notifier_call_chain(&psy_battery_info_notifier,
> +				PSY_BATT_INFO_REGISTERED, info);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(psy_register_battery_info);
> +
> +void psy_unregister_battery_info(struct psy_charging_obj *info)
> +{
> +	struct psy_battery_info *battery, *tmp;
> +
> +	list_for_each_entry_safe(battery, tmp, &psy_battery_info_list, entry) {
> +		if (battery->info == info) {
> +			list_del(&battery->entry);
> +			kfree(battery);
> +			return;
> +		}
> +	}
> +
> +	atomic_notifier_call_chain(&psy_battery_info_notifier,
> +				PSY_BATT_INFO_UNREGISTERED, info);
> +}
> +EXPORT_SYMBOL(psy_unregister_battery_info);
> +
>  MODULE_DESCRIPTION("Universal power supply monitor class");
>  MODULE_AUTHOR("Ian Molton <spyro@f2s.com>, "
>  	      "Szabolcs Gyurko, "
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 7aada44..30145d8e 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -279,6 +279,11 @@ struct psy_charging_obj {
>  	struct psy_temp_mon_table temp_mon_table[PSY_MAX_TEMP_ZONE];
>  };
>  
> +enum battery_info_notifier_events {
> +	PSY_BATT_INFO_REGISTERED,
> +	PSY_BATT_INFO_UNREGISTERED,
> +};
> +
>  extern struct atomic_notifier_head power_supply_notifier;
>  extern int power_supply_reg_notifier(struct notifier_block *nb);
>  extern void power_supply_unreg_notifier(struct notifier_block *nb);
> @@ -311,6 +316,13 @@ extern int power_supply_powers(struct power_supply *psy, struct device *dev);
>  /* For APM emulation, think legacy userspace. */
>  extern struct class *power_supply_class;
>  
> +/* Battery information helper */
> +extern int psy_battery_info_notifier_register(struct notifier_block *);
> +extern void psy_battery_info_notifier_unregister(struct notifier_block *);
> +extern struct psy_charging_obj *psy_get_battery_info(const char *);
> +extern int psy_register_battery_info(struct psy_charging_obj *);
> +extern void psy_unregister_battery_info(struct psy_charging_obj *);
> +
>  static inline bool power_supply_is_amp_property(enum power_supply_property psp)
>  {
>  	switch (psp) {


-- 
Oliver Neukum <oneukum@suse.de>