power: supply: max17040: Send uevent in SOC and status change

Notify core through power_supply_changed() in case of changes in state
of charge and power supply status. This is useful for user-space to
efficiently update current battery level.
Signed-off-by: Matheus Castello <matheus@castello.eng.br>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/max17040_battery.c

@@ -207,10 +207,19 @@ static void max17040_check_changes(struct i2c_client *client)
 static void max17040_work(struct work_struct *work)
 {
 	struct max17040_chip *chip;
+	int last_soc, last_status;
 
 	chip = container_of(work, struct max17040_chip, work.work);
+
+	/* store SOC and status to check changes */
+	last_soc = chip->soc;
+	last_status = chip->status;
 	max17040_check_changes(chip->client);
 
+	/* check changes and send uevent */
+	if (last_soc != chip->soc || last_status != chip->status)
+		power_supply_changed(chip->battery);
+
 	queue_delayed_work(system_power_efficient_wq, &chip->work,
 			   MAX17040_DELAY);
 }