power_supply: Add power_supply notifier

This patch adds a notifier chain to the power_supply, this helps drivers
in other subsystem to listen to changes in power supply subsystem.

This would help to take some actions in those drivers on changing the
power supply properties. One such scenario is to increase/decrease system
performance based on the battery capacity/voltage. Another scenario is to
adjust the h/w peak current detection voltage/current thresholds based on
battery voltage/capacity. The notifier helps drivers to listen to changes
in power_suppy susbystem without polling the power_supply properties

Signed-off-by: Jenny TC <jenny.tc@intel.com>
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Jenny TC <jenny.tc@intel.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 557af943b2f5..6aac23cc6566 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/notifier.h>
 #include <linux/err.h>
 #include <linux/power_supply.h>
 #include <linux/thermal.h>
@@ -24,6 +25,9 @@
 struct class *power_supply_class;
 EXPORT_SYMBOL_GPL(power_supply_class);
 
+ATOMIC_NOTIFIER_HEAD(power_supply_notifier);
+EXPORT_SYMBOL_GPL(power_supply_notifier);
+
 static struct device_type power_supply_dev_type;
 
 static bool __power_supply_is_supplied_by(struct power_supply *supplier,
@@ -80,6 +84,8 @@ static void power_supply_changed_work(struct work_struct *work)
                 class_for_each_device(power_supply_class, NULL, psy,
                                       __power_supply_changed_work);
                 power_supply_update_leds(psy);
+                atomic_notifier_call_chain(&power_supply_notifier,
+                                PSY_EVENT_PROP_CHANGED, psy);
                 kobject_uevent(&psy->dev->kobj, KOBJ_CHANGE);
                 spin_lock_irqsave(&psy->changed_lock, flags);
         }
@@ -347,6 +353,18 @@ static void power_supply_dev_release(struct device *dev)
         kfree(dev);
 }
 
+int power_supply_reg_notifier(struct notifier_block *nb)
+{
+        return atomic_notifier_chain_register(&power_supply_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(power_supply_reg_notifier);
+
+void power_supply_unreg_notifier(struct notifier_block *nb)
+{
+        atomic_notifier_chain_unregister(&power_supply_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(power_supply_unreg_notifier);
+
 #ifdef CONFIG_THERMAL
 static int power_supply_read_temp(struct thermal_zone_device *tzd,
                 unsigned long *temp)